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Find video protocols related to scientific articles indexed in Pubmed.
How good can CVD-grown monolayer graphene be?
Nanoscale
PUBLISHED: 11-10-2014
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Chemical vapor deposition (CVD) is considered the most promising method for pushing graphene into commercial products. However, CVD grown graphene is usually of low quality. In this work we explore how good can CVD-derived monolayer graphene be. Through the combinational optimization of the main processes of growth, transfer, device fabrication and measurements, we show that the optimized CVD graphene can present performance comparable to mechanical exfoliated ones: in particular, high carrier mobility at room temperature on the Si/SiO2 substrate, perfect electron-hole symmetry and excellent uniformity (the mobility ranged from 5000 to 12?000 cm(2) V(-1) s(-1) with an average mobility of ?8800 cm(2) V(-1) s(-1) and 50% were higher than 10?000 cm(2) V(-1) s(-1)). In addition we found that the adsorbed oxygen and water molecules on graphene lead to p-type doping in graphene, and transferred charges bring charged impurity scattering to the transporting carriers in the graphene channel. It is therefore necessary to carry out electrical measurements under vacuum to obtain high intrinsic carrier mobility CVD grown graphene.
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Biomechanical study of the funnel technique applied in thoracic pedicle screw replacement.
Afr Health Sci
PUBLISHED: 10-30-2014
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Funnel technique is a method used for the insertion of screw into thoracic pedicle.
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The performance of transrectal ultrasound in the diagnosis of seminal vesicle defects: a comparison with magnetic resonance imaging.
Asian J. Androl.
PUBLISHED: 10-23-2014
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Obstructive azoospermia (OA) is one of the most common causes of male infertility. Transrectal ultrasound (TRUS) has been used to diagnose OA for many years. From 2009 to 2013, we evaluated a prospective cohort of 1249 patients with suspected OA using TRUS. It was found that dilation of the ejaculatory duct (ED) (29.9%, 374/1249) was the most common cause of OA, followed by seminal vesicle (SV) abnormalities (28.5%, 356/1249). A total of 237 patients were diagnosed with congenital defects (agenesis and/or hypoplasia) of the SV, constituting more than half of the cases of SV disease in OA (19.0%, 237/1249). In contrast to ED, congenital defects of the SV could not be corrected with surgical treatment. Therefore, it is meaningful to compare TRUS and magnetic resonance imaging (MRI) for accurate diagnosis of SV defects. Among our patients, 30 with agenesis or/and hypoplasia of the SV on TRUS were further evaluated using pelvic MRI within 2 years, with the objective of verifying the TRUS results. The concordance rate for diagnosing congenital defects of the SV was 73.3% (22/30). We concluded that TRUS is a reliable and convenient method for diagnosing agenesis or hypoplasia of the SV in OA patients with a high concordance with MRI while MRI is useful in patients with inconclusive TRUS findings.
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Floating Growth of Large-Scale Freestanding TiO2 Nanorod Films at the Gas-Liquid Interface for Additive-Free Li-Ion Battery Applications.
ACS Appl Mater Interfaces
PUBLISHED: 10-03-2014
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The floating growth process of large-scale freestanding TiO2 nanorod films at the gas-liquid interface was investigated. On the basis of the experiments, a self-templated growth scenario was developed to account for the self-assembly process. In the scenario, titanium complexes function not only as the Ti source for the growth of TiO2 but also as a soft template provider for the floating growth. According to the scenario, several new recipes of preparing freestanding TiO2 nanorod films at the gas-liquid interface were developed. The freestanding film was applied to a lithium ion battery as a binder-free and conducting agent-free anode, and good cyclability was obtained. This work may pave a new way to floating and freestanding TiO2 and other semiconductor materials, which has great potential not only in basic science but also in the applications such as materials engineering, Li-ion battery, photocatalyst, dye-sensitized solar cell, and flexible electronics.
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Organohalide lead perovskite based photodetectors with much enhanced performance.
Chem. Commun. (Camb.)
PUBLISHED: 09-24-2014
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CH3NH3PbI3 based photodetectors were fabricated by a facile low-cost process with much enhanced performance. The rise time changed from 2.7 s to 0.02 s, the decay time from 0.5 s to 0.02 s, and the ON/OFF ratio tripled with improved stability. The results indicate that perovskites are promising light-harvesting materials for photodetectors.
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Comparison between laparoscopic partial nephrectomy and laparoscopic ablation therapy: A meta-analysis.
Minim Invasive Ther Allied Technol
PUBLISHED: 09-02-2014
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Abstract Objective: To conduct a meta-analysis of the literature evaluating comparisons on the peri-operative and oncological outcomes between laparoscopic partial nephrectomy (LPN) and laparoscopic ablation therapy (LAT) in the treatment of small renal masses (SRMs).
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Exploration of yttria films as gate dielectrics in sub-50 nm carbon nanotube field-effect transistors.
Nanoscale
PUBLISHED: 08-21-2014
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Thin yttria films were investigated for use as gate dielectrics in carbon nanotube field-effect transistors (CNTFETs) with the gate length scaled down to sub-50 nm size. The yttria film provided an omega-shaped gate dielectric with a low interface trap density, a low average sub-threshold swing of 74 mV per decade for both long and short CNTFETs, and a small drain-induced barrier lowering. It was also shown that the performance of CNTFETs increases with decreasing temperature, with an excellent sub-threshold swing of 22 mV per decade at liquid nitrogen temperatures. A method was developed to retrieve the interface trap density in CNTFETs and a low interface trap density of 5.2 × 10(6) cm(-1) was achieved, indicating the high electric quality of the yttria films.
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UV damage-induced RNA polymerase II stalling stimulates H2B deubiquitylation.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 08-18-2014
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Histone H2B monoubiquitylation plays an important role in RNA polymerase II (RNAPII) elongation. Whether this modification responds to RNAPII stalling is not yet known. We report that both yeast and human cells undergo a rapid and significant H2B deubiquitylation after exposure to UV irradiation. This deubiquitylation occurs concurrently with UV-induced transcription arrest and is significantly reduced in a DNA damage-bypassing RNAPII yeast mutant. Consistent with these results, yeast deubiquitylases Ubp8 and Ubp10 are associated with the RNAPII complex. Moreover, simultaneous deletion of Ubp8 and Ubp10 leads to a lack of H2B deubiquitylation after UV exposure. Consequently, nucleotide excision repair at an actively transcribed gene locus is decreased, whereas UV-induced RNAPII degradation is increased in ubp8?ubp10? mutant cells. These results indicate that eukaryotic cells respond to RNAPII arrest by deubiquitylating H2B to coordinate DNA repair and RNAPII degradation.
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Length scaling of carbon nanotube electric and photo diodes down to sub-50 nm.
Nano Lett.
PUBLISHED: 08-15-2014
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Carbon nanotubes (CNTs) are promising candidates for future optoelectronics and logic circuits.1-3 Sub-10 nm channel length CNT transistors have been demonstrated with superb performance.4 Yet, the scaling of CNT p-n diodes or photodiodes, basic elements for most optoelectronic devices, is held back on a scale of micrometers.5-8 Here, we demonstrate that CNT diodes fabricated via a dopant-free technique show good rectifying characteristics and photovoltaic response even when the channel length is scaled to sub-50 nm. By making a trade-off between performance and size, a diode with both channel length and contact width around 100 nm, fabricated on a CNT with a small diameter (d ? 1.2 nm), shows a photovoltage of 0.24 V and a fill factor of up to 60%. Study on the dependence of turn-on voltage on scaled channel length reveals transferred charges induced potential barrier at the contact in long channel diodes and the effect of self-adjusting charge distribution. This effect could be utilized for realizing stable and high performance sub-100 nm pitch CNT diodes. As elementary building blocks, such tiny electric and photodiodes could be used in nanoscale rectifiers, photodetectors, light sources, and high-efficiency photovoltaic devices.
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Facile fabrication of three-dimensional graphene foam/poly(dimethylsiloxane) composites and their potential application as strain sensor.
ACS Appl Mater Interfaces
PUBLISHED: 08-07-2014
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A three-dimensional (3D) graphene foam (GF)/poly(dimethylsiloxane) (PDMS) composite was fabricated by infiltrating PDMS into 3D GF, which was synthesized by chemical vapor deposition (CVD) with nickel foam as template. The electrical properties of the GF/PDMS composite under bending stress were investigated, indicating the resistance of the GF/PDMS composite was increased with the bending curvature. To improve the bending sensitivity of the GF/PDMS composite, a thin layer of poly(ethylene terephthalate) (PET) was introduced as substrate to form double-layer GF/PDMS-PET composite, whose measurements showed that the resistance of the GF/PDMS-PET composite was still increased when bended to the side of PET, whereas its resistance would be decreased when bended to the side of GF. For both cases, the absolute value of the relative variation of electrical resistance was increased with the bending curvature. More importantly, the relative variation of electrical resistance for double-layer GF/PDMS-PET composite can be up to six times higher than single-layer GF/PDMS composite for the same bending curvature. These observations were further supported by the principle of mechanics of material. The 3D GF/PDMS-PET composite also has higher flexibility and environment stability and can be utilized as a strain sensor with high sensitivity, which can find important applications in real-time monitoring of buildings, such as a bridge, dam, and high-speed railway.
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Extraction of light trapped due to total internal reflection using porous high refractive index nanoparticle films.
Nanoscale
PUBLISHED: 06-14-2014
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TiO? nanoparticle layers composed of columnar TiO? nanoparticle piles separated with nanoscale pores were fabricated on the bottom surface of the hemispherical glass prism by performing gas phase cluster beam deposition at glancing incidence. The porosity as well as the refractive index of the nanoparticle layer was precisely tuned by the incident angle. Effective extraction of the light trapped in the substrate due to total internal reflection with the TiO? nanoparticle layers was demonstrated and the extraction efficiency was found to increase with the porosity. An enhanced Rayleigh scattering mechanism, which results from the columnar aggregation of the nanoparticles as well as the strong contrast in the refractive index between pores and TiO? nanoparticles in the nanoporous structures, was proposed. The porous TiO? nanoparticle coatings were fabricated on the surface of GaN LEDs to enhance their light output. A nearly 92% PL enhancement as well as a 30% EL enhancement was observed. For LED applications, the enhanced light extraction with the TiO? nanoparticle porous layers can be a supplement to the microscale texturing process for light extraction enhancement.
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[Suture anchor for acute injuries of medial collateral ligament of knee at degree III].
Zhongguo Gu Shang
PUBLISHED: 05-16-2014
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To evaluate clinical efficacy of suture anchors in treating acute injuries of medial collateral ligament (MCL) of knee at degree III.
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Modularized construction of general integrated circuits on individual carbon nanotubes.
Nano Lett.
PUBLISHED: 05-08-2014
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While constructing general integrated circuits (ICs) with field-effect transistors (FETs) built on individual CNTs is among few viable ways to build ICs with small dimension and high performance that can be compared with that of state-of-the-art Si based ICs, this has not been demonstrated owing to the absence of valid and well-tolerant fabrication method. Here we demonstrate a modularized method for constructing general ICs on individual CNTs with different electric properties. A pass-transistor-logic style 8-transistor (8-T) unit is built, demonstrated as a multifunctional function generator with good tolerance to inhomogeneity in the CNTs used and used as a building block for constructing general ICs. As an example, an 8-bits BUS system that is widely used to transfer data between different systems in a computer is constructed. This is the most complicated IC fabricated on individual CNTs to date, containing 46 FETs built on six individual semiconducting CNTs. The 8-T unit provides a good basis for constructing complex ICs to explore the potential and limits of CNT ICs given the current imperfection in available CNT materials and may also be developed into a universal and efficient way for constructing general ICs on ideal CNT materials in the future.
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Electroluminescence from serpentine carbon nanotube based light-emitting diodes on quartz.
Small
PUBLISHED: 05-07-2014
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A light-emitting diode is fabricated and characterized on a semiconducting serpentine CNT which has many parallel segments with identical chirality. Compared with the individual CNT and CNT-film devices, the device with parallel segments shows improvement of an order of magnitude in current, significantly larger electroluminescent intensity, and narrower emission bands. Serpentine nanotubes are an ideal choice for practical applications of CNT-based light sources.
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Graphene/Si CMOS hybrid hall integrated circuits.
Sci Rep
PUBLISHED: 05-02-2014
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Graphene/silicon CMOS hybrid integrated circuits (ICs) should provide powerful functions which combines the ultra-high carrier mobility of graphene and the sophisticated functions of silicon CMOS ICs. But it is difficult to integrate these two kinds of heterogeneous devices on a single chip. In this work a low temperature process is developed for integrating graphene devices onto silicon CMOS ICs for the first time, and a high performance graphene/CMOS hybrid Hall IC is demonstrated. Signal amplifying/process ICs are manufactured via commercial 0.18?um silicon CMOS technology, and graphene Hall elements (GHEs) are fabricated on top of the passivation layer of the CMOS chip via a low-temperature micro-fabrication process. The sensitivity of the GHE on CMOS chip is further improved by integrating the GHE with the CMOS amplifier on the Si chip. This work not only paves the way to fabricate graphene/Si CMOS Hall ICs with much higher performance than that of conventional Hall ICs, but also provides a general method for scalable integration of graphene devices with silicon CMOS ICs via a low-temperature process.
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Chromatin remodelling complex RSC promotes base excision repair in chromatin of Saccharomyces cerevisiae.
DNA Repair (Amst.)
PUBLISHED: 01-07-2014
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The base excision repair (BER) pathway is a conserved DNA repair system required to maintain genomic integrity and prevent mutagenesis in all eukaryotic cells. Nevertheless, how BER operates in vivo (i.e. in the context of chromatin) is poorly understood. We have investigated the role of an essential ATP-dependent chromatin remodelling (ACR) complex RSC (Remodels the Structure of Chromatin) in BER of intact yeast cells. We show that depletion of STH1, the ATPase subunit of RSC, causes enhanced sensitivity to the DNA alkylating agent methyl methanesulfonate (MMS) and results in a substantial inhibition of BER, at the GAL1 locus and in the genome overall. Consistent with this observation, the DNA in chromatin is less accessible to micrococcal nuclease digestion in the absence of RSC. Quantitative PCR results indicate that repair deficiency in STH1 depleted cells is not due to changes in the expression of BER genes. Collectively, our data indicates the RSC complex promotes efficient BER in chromatin. These results provide, for the first time, a link between ATP-dependent chromatin remodelling and BER in living cells.
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Plasma Amyloid-? Oligomers and Soluble Tumor Necrosis Factor Receptors as Potential Biomarkers of AD.
Curr Alzheimer Res
PUBLISHED: 01-03-2014
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Amyloid beta (A?), especially A? oligomers, is important in early Alzheimer's disease (AD) pathogenesis. AD-associated inflammation has generally been considered as a secondary response to the pathological lesions evoked by A? oligomers in the early stage of pathogenesis. We studied the levels of plasma A? monomers, A? oligomers, and soluble tumor necrosis factor ? receptors (sTNFRs) in 120 controls, 32 amnestic mild cognitive impairment (aMCI) patients, and 90 mild AD patients. The plasma A? monomer, oligomer and sTNFR levels were measured by ELISA. We observed that the A? oligomer levels in mild AD patients were significantly higher than those in aMCI (200.8±83.8 versus 93.9±23.3, P<0.05) and healthy subjects (200.8±83.8 versus 70.0±60.9, P<0.05). The sTNFR levels in the plasma of aMCI and mild AD patients were significantly higher than the levels of control subjects. Moreover, the levels of both sTNFR1 and sTNFR2 were significantly correlated with A? oligomer levels in aMCI (sTNFR1 : r= 0.376, P= 0.034; sTNFR2 : r= 0.367, P= 0.039) and mild AD patients (sTNFR1 : r= 0.471, P< 0.001; sTNFR2 : r= 0.407, P< 0.001). More importantly, changes in A? oligomer and sTNFR levels accurately differentiated mild AD patients from control subjects, supporting these levels might be potential diagnostic biomarkers for aMCI and AD.
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Epidemiological Study and Control Trial of Taeniid Cestode Infection in Farm Dogs in Qinghai Province, China.
J. Vet. Med. Sci.
PUBLISHED: 11-21-2013
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An epidemiological study and control trial were conducted to assess taeniid infection in farm dogs in Qinghai Province, China. To improve egg detection by fecal examination, a deworming step with praziquantel was incorporated into the sampling methodology. As a result, a marked increase in the number of egg-positive samples was observed in samples collected at 24 hr after deworming. Then, the fecal examination and barcoding of egg DNA were performed to assess the prevalence of taeniid species in dogs from Xinghai, Haiyan, Gangcha and Chengduo counties. Analysis of 277 dog feces revealed that taeniid cestodes, including Taenia spp. and Echinococcus granulosus, were highly prevalent in Xinghai (34.4%), but eggs were not found in Haiyan where a control trial on canine echinococcosis had been conducted 20 years previously. A control trial involving the administration of 5-10 mg/kg praziquantel to 90 farm dogs at 45-day intervals was conducted in Xinghai. The prevalence of taeniid cestodes in the dogs was reduced to 9.6% and 4.9% after one and two years, respectively, indicating that some dogs were not administered praziquantel properly. A questionnaire survey of farmers in Xinghai and Haiyan revealed that most farmers in Xinghai were not familiar with echinococcosis or the transmission route of the disease, while most farmers in Haiyan had a more thorough understanding of the disease. The findings implied that a program for educating local farmers would be important for efficiently controlling canine taeniid infection in the region.
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Identification of Enriched PTM Crosstalk Motifs from Large-Scale Experimental Data Sets.
J. Proteome Res.
PUBLISHED: 10-23-2013
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Post-translational modifications (PTMs) play an important role in the regulation of protein function. Mass spectrometry based proteomics experiments nowadays identify tens of thousands of PTMs in a single experiment. A wealth of data has therefore become publically available. Evidently the biological function of each PTM is the key question to be addressed; however, such analyses focus primarily on single PTM events. This ignores the fact that PTMs may act in concert in the regulation of protein function, a process termed PTM crosstalk. Relatively little is known on the frequency and functional relevance of crosstalk between PTM sites. In a bioinformatics approach, we extracted PTMs occurring in proximity in the protein sequence from publically available databases. These PTMs and their flanking sequences were subjected to stringent motif searches, including a scoring for evolutionary conservation. Our unprejudiced approach was able to detect a respectable set of motifs, of which about half were described previously. Among these we could add many new proteins harboring these motifs. We extracted also several novel motifs, which through their widespread appearance and high conservation may pinpoint at previously nonannotated concerted PTM actions. By employing network analyses on these proteins, we propose putative functional roles for these novel motifs with two PTM sites in close proximity.
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An Epidemiological Study of Hypoderma Infection and Control Using Ivermectin in Yaks in Qinghai Province, China.
J. Vet. Med. Sci.
PUBLISHED: 10-10-2013
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The prevalence of Hypoderma spp. in yaks grazed in the east of Qinghai province was investigated in 2008. In this area, the prevalence in young yaks (1- to 3-year-old) was very high at 82.2-98.7%, whilst in adult yaks (4-year-old and older), the prevalence was 42.4-50.6%. The seasonal development and migration pattern of Hypoderma larvae in yak bodies was found to be similar for different locations in this area. The numbers of first, second and third instar larvae detected in yak bodies peaked in October, December and March, respectively. Different doses of ivermectin (125 to 500 µg/kg body weight) almost completely dewormed the larvae from yaks, suggesting that using a quarter of the prescribed dose (500 µg/kg body weight) was effective. In October of each year between 2009 and 2012, ivermectin (125 µg/kg body weight) was administered to a total of 562,995 yaks grazed in four counties in Qinghai province, and the pevalence of Hypoderma larval infection in yaks was reduced to 0.5-1.0%.
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Self-assembly of large-scale floating TiO2 nanorod arrays at the gas-liquid interface.
ACS Appl Mater Interfaces
PUBLISHED: 09-04-2013
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This paper describes a facile one-step synthesis of large-scale floating TiO2 nanorod arrays via a hydrothermal reaction without using any surfactants, which opens a new way to prepare floating photocatalysts for photodecomposition of floating organics and free-standing nanorod arrays for flexible dye-sensitized solar cells. A general model is developed to analyze the driving force for the floating TiO2 film, which may be also useful for other two-dimensional materials to determine the obtainable size of an arbitrary shaped film floated by surface tension and buoyancy.
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Preparation of reduced graphene oxide by infrared irradiation induced photothermal reduction.
Nanoscale
PUBLISHED: 08-12-2013
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We present a green and scalable route toward the formation of reduced graphene oxide (r-GO) by photothermal reduction induced by infrared (IR) irradiation, utilizing a bathroom IR lamp as the source of IR light. Thermogravimetric analysis, Raman, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirm the reduction of r-GO by IR light. Ultraviolet-visible-infrared spectra indicate that adsorption of IR light by original GO films is less than that of UV and visible light; but when GO is exposed to IR light, its adsorption of IR light increases very rapidly with time. The influence of the power density of the IR light on the structure and properties of r-GO was investigated. At high IR power density, the reduction reaction was so fierce that r-GO became highly porous due to the rapid degassing and exfoliation of GO sheets. The r-GO powder revealed good performance as the anode material for lithium ion batteries. At relatively low IR power density, the reduction process was found to be mild but relatively slow. Crack-free and uniform conductive r-GO thin films with a volume conductivity of 1670 S m(-1) were then prepared by two-step IR irradiation, i.e. first at low IR power density and then at high IR power density. Moreover, the r-GO films were also observed to exhibit obvious and reversible IR light-sensing behavior.
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Survey on helminths in the small intestine of wild foxes in Qinghai, China.
J. Vet. Med. Sci.
PUBLISHED: 07-10-2013
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The intestinal helminth fauna of Tibetan sand foxes (Vulpes ferrilata) and red foxes (Vulpes vulpes) inhabiting in Qinghai, China, was evaluated by conducting necropsy of hunted foxes and fecal egg examination of field-collected feces. In northeast and south Qinghai, 36 foxes were necropsied, and the species of foxes and the parasites detected were identified by the DNA barcoding. In 27 red foxes and 9 Tibetan sand foxes examined, Mesocestoides litteratus (total prevalence: 64%), Toxascaris leonina (50%), Taenia pisiformis (8%) and Taenia crassiceps (8%) were found in both species of foxes. Echinococcus shiquicus (8%) and Taenia multiceps (6%) were found only in Tibetan sand foxes. Echinococcus multilocularis (3%) and Alaria alata (8%) were found only in red foxes. In the fecal egg examination of the rectal feces, 100% of taeniid cestodes, 73% of Toxascaris and 27% of Mesocestoides worm-positive samples showed egg-positive, indicating that coprological survey for parasite eggs could only provide partial information of intestinal parasite fauna. For field-collected feces, molecular identification of feces origins and fecal egg examination were performed. In 15 Tibetan sand fox and 30 red fox feces, we found E. multilocularis eggs in one feces of Tibetan sand fox. The present study indicated that the upper intestinal helminth fauna of the two fox species in Qinghai does not differ significantly and both species would play an important role in the maintenance of taeniid cestodes.
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Fabrication of bimetallic microfluidic surface-enhanced Raman scattering sensors on paper by screen printing.
Anal. Chim. Acta
PUBLISHED: 04-09-2013
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Au-Ag bimetallic microfluidic, dumbbell-shaped, surface enhanced Raman scattering (SERS) sensors were fabricated on cellulose paper by screen printing. These printed sensors rely on a sample droplet injection zone, and a SERS detection zone at either end of the dumbbell motif, fabricated by printing silver nanoparticles (Ag NPs) and gold nanoparticles (Au NPs) successively with microscale precision. The microfluidic channel was patterned using an insulating ink to connect these two zones and form a hydrophobic circuit. Owing to capillary action of paper in the millimeter-sized channels, the sensor could enable self-filtering of fluids to remove suspended particles within wastewater without pumping. This sensor also allows sensitive SERS detection, due to advantageous combination of the strong surface enhancement of Ag NPs and excellent chemical stability of Au NPs. The SERS performance of the sensors was investigated by employing the probe rhodamine 6G, a limit of detection (LOD) of 1.1×10(-13)M and an enhancement factor of 8.6×10(6) could be achieved. Moreover, the dumbbell-shaped bimetallic sensors exhibited good stability with SERS performance being maintained over 14 weeks in air, and high reproducibility with less than 15% variation in spot-to-spot SERS intensity. Using these dumbbell-shaped bimetallic sensors, substituted aromatic pollutants in wastewater samples could be quantitatively analyzed, which demonstrated their excellent capability for rapid trace pollutant detection in wastewater samples in the field without pre-separation.
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Phase separation induced molecular fractionation of gum arabic--sugar beet pectin systems.
Carbohydr Polym
PUBLISHED: 04-01-2013
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This paper investigates the phase separation and phase separation-induced fractionation of gum arabic (GA)/sugar beet pectin (SBP) mixed solutions. A phase diagram, including cloud and binodal curves, was established by visual observation and phase composition analysis. The deviation of the binodal curve from the cloud curve was a result of phase separation-induced fractionation of polydisperse GA and SBP molecules. Fractionation of GA increased the content of arabinogalactan-protein complex (AGP) from ca. 13% to 27%. The fractionated GA (FGA) showed improved emulsifying functionality, whereas the fractionated SBP (FSBP) had a reduced emulsifying functionality. The changes in emulsifying efficiency can be explained by interfacial adsorption behaviors at the oil-water interface as indicated by interfacial tension measurements.
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Finding the same needles in the haystack? A comparison of phosphotyrosine peptides enriched by immuno-affinity precipitation and metal-based affinity chromatography.
J Proteomics
PUBLISHED: 03-27-2013
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Analysis of tyrosine (Tyr) phosphorylation by mass spectrometry (MS)-based proteomics remains challenging, due to the low occurrence of this post-translational modification compared to serine and threonine phosphorylation events in mammalian systems. Conventional metal-based affinity chromatography methods used to enrich phosphopeptides can nowadays isolate over 10,000 phosphopeptides. However, these approaches are not particularly suitable for the selective enrichment of low abundant Tyr phosphorylated peptides as the higher abundant co-enriched serine (Ser) and threonine (Thr) phosphorylated peptides typically obscure their detection. Therefore, a more targeted approach based on immuno-affinity precipitation at the peptide level has been introduced for the specific analysis of Tyr phosphorylated species. This method typically leads to the detection of a few hundreds of phosphopeptides, albeit typically over 70% of those are Tyr phosphorylated. Here, we evaluated and compared phosphotyrosine peptides enriched by a phospho-Tyr immuno-affinity enrichment (employing pY99 antibodies) and a multidimensional approach consisting of metal-affinity based enrichment (Ti(4+)-IMAC) followed by hydrophilic interaction liquid chromatography (HILIC) fractionation. Our aim was to assess differences and similarities in the set of Tyr phosphorylated peptides detected by each approach. Our data suggest that both strategies are not redundant but complementary and should ideally be combined for a more comprehensive view at phosphotyrosine signaling.
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Construction of flame retardant nanocoating on ramie fabric via layer-by-layer assembly of carbon nanotube and ammonium polyphosphate.
Nanoscale
PUBLISHED: 03-06-2013
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A new flame retardant nanocoating has been constructed by the alternate adsorption of polyelectrolyte amino-functionalized multiwall carbon nanotube (MWNT-NH2) and ammonium polyphosphate (APP) onto flexible and porous ramie fabric. Scanning electron microscopy indicates that the adsorbed carbon nanotube coating is a randomly oriented and overlapped network structure, which is a promising candidate for flame retardancy applications. Attenuated total reflection Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis confirm that the APP is successfully incorporated into the multilayers sequentially. Assessment of the thermal and flammability properties for the pristine and nanocoated ramie fabrics shows that the thermal stability, flame retardancy and residual char are enhanced as the concentration of MWNT-NH2 suspension and number of deposition cycles increases. The enhancements are mostly attributed to the barrier effect of intumescent network structure, which is composed of MWNT-NH2 and the absorbed APP.
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Carrier sheet density constrained anomalous current saturation of graphene field effect transistors: kinks and negative differential resistances.
Nanoscale
PUBLISHED: 02-27-2013
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There has recently been a great deal of interest and excitement in applying graphene field effect transistors (GFETs) in digital and radio frequency (RF) circuits and systems. Peculiar output characteristics such as kinks and negative differential resistance (NDR) in a strong field are the unique transport properties of GFETs. Here we demonstrate that these unusual features are attributed to a carrier sheet density constrained transport framework. Simulation results based on a simple analytic model which includes the linear DOS structure are in very good agreement with experimental data. The kernel mechanism of NDR is ascribed to the fact that the total current increase of a channel with a high average carrier density is constrained by its minimum sheet density. Utilizing in situ Kelvin probe force microscopy (KPFM), the principle which naturally distinguishes NDR from kinks is further verified by studying the spatially resolved surface potential distribution along the channel. The influence and potential application of GFETs unique output characteristics in the digital and RF fields are also proposed.
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Batch-fabricated high-performance graphene Hall elements.
Sci Rep
PUBLISHED: 02-04-2013
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Hall elements are by far the most widely used magnetic sensor. In general, the higher the mobility and the thinner the active region of the semiconductor used, the better the Hall device. While most common magnetic field sensors are Si-based Hall sensors, devices made from III-V compounds tend to favor over that based on Si. However these devices are more expensive and difficult to manufacture than Si, and hard to be integrated with signal-processing circuits for extending function and enforcing performance. In this article we show that graphene is intrinsically an ideal material for Hall elements which may harness the remarkable properties of graphene, i.e. extremely high carrier mobility and atomically thin active body, to create ideal magnetic sensors with high sensitivity, excellent linearity and remarkable thermal stability.
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Carbon nanotube photoelectronic and photovoltaic devices and their applications in infrared detection.
Small
PUBLISHED: 01-22-2013
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Semiconducting carbon nanotubes (CNTs) are direct bandgap materials with outstanding electronic and optoelectronic properties and have been investigated for various electronic and optoelectronic device applications, such as light-emitting diodes, photodetectors and photovoltaic cells. Here, a brief review of the various types of CNT diodes is presented, with a focus on one particular type of CNT diodes fabricated via a doping-free process. Their application for constructing high-performance optoelectronic and photovoltaic devices is also discussed, as well as the newly discovered photovoltage multiplication effect in CNTs and its application in improving the efficiency of CNT-based infrared detector.
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Cancer stem cell-like side population cells in clear cell renal cell carcinoma cell line 769P.
PLoS ONE
PUBLISHED: 01-01-2013
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Although cancers are widely considered to be maintained by stem cells, the existence of stem cells in renal cell carcinoma (RCC) has seldom been reported, in part due to the lack of unique surface markers. We here identified cancer stem cell-like cells with side population (SP) phenotype in five human RCC cell lines. Flow cytometry analysis revealed that 769P, a human clear cell RCC cell line, contained the largest amount of SP cells as compared with other four cell lines. These 769P SP cells possessed characteristics of proliferation, self-renewal, and differentiation, as well as strong resistance to chemotherapy and radiotherapy that were possibly related to the ABCB1 transporter. In vivo experiments with serial tumor transplantation in mice also showed that 769P SP cells formed tumors in NOD/SCID mice. Taken together, these results indicate that 769P SP cells have the properties of cancer stem cells, which may play important roles in tumorigenesis and therapy-resistance of RCC.
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[The cup safe-zone and optimum combination of the acetabular and femoral anteversions that fulfills the desired range of motion of the hip].
Zhongguo Gu Shang
PUBLISHED: 10-31-2011
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To investigate safe range of acetabular prosthesis angle and the optimum combination of cup and neck in the range of activities of daily living (ADL).
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Toward clean and crackless transfer of graphene.
ACS Nano
PUBLISHED: 10-19-2011
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We present the results of a thorough study of wet chemical methods for transferring chemical vapor deposition grown graphene from the metal growth substrate to a device-compatible substrate. On the basis of these results, we have developed a "modified RCA clean" transfer method that has much better control of both contamination and crack formation and does not degrade the quality of the transferred graphene. Using this transfer method, high device yields, up to 97%, with a narrow device performance metrics distribution were achieved. This demonstration addresses an important step toward large-scale graphene-based electronic device applications.
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Oncogenic roles of astrocyte elevated gene-1 (AEG-1) in osteosarcoma progression and prognosis.
Cancer Biol. Ther.
PUBLISHED: 09-15-2011
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Astrocyte elevated gene-1 (AEG-1) is overexpressed in several cancers and plays an important role in cancer progression. However, AEG-1 expression, biological function, and clinical significance in osteosarcoma have not been uncovered. Utilizing manipulated human osteosarcoma cell lines and osteosarcoma tissues, we found that increasing expression of AEG-1 enhanced osteosarcoma cell proliferation and invasion in vitro, and knockdown of AEG-1 significantly attenuated osteosarcoma cell malignancy. Moreover, AEG-1 was overexpressed in osteosarcoma tissues, and overexpression of AEG-1 was strongly associated with gender (p = 0.018), clinical stages (p < 0.001), classification (p < 0.001), metastasis (p = 0.013), differentiation (p < 0.001), and poor survival (p = 0.021). Mechanistic studies conducted in vitro and in vivo revealed that AEG-1-mediated carcinogenesis and invasiveness might be through upregulating MMP-2. Taken together, our data strongly suggest that AEG-1 plays a crucial role in osteosarcoma progression through MMP-2, and AEG-1 could be a useful biomarker for the prediction of osteosarcoma progression and prognosis.
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Percolation-dominated superhydrophobicity and conductivity for nanocomposite coatings from the mixtures of a commercial aqueous silica sol and functionalized carbon nanotubes.
J Colloid Interface Sci
PUBLISHED: 07-26-2011
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Superhydrophobic conductive nanocomposite coatings are prepared for the first time from the simple mixture of a commercial aqueous silica sol and functionalized multiwalled carbon nanotubes (MWNTs) by air-spraying at ambient conditions followed by fluorosilane treatment. The relationship between MWNT content and the structure and properties of the nanocomposite coatings is investigated systematically. An ultra-low threshold (<5 vol.%) for superhydrophobicity is observed, which suggests that MWNTs are superior to any other spherical fillers for the construction of superhydrophobic nanocomposite coatings. When the content of nanotubes is below the threshold, the surface roughness mainly caused by the silica nanoparticles is not enough for creating superhydrophobic surfaces. Only above the threshold, the multiscale hierarchical structure is enough for both high water contact angles (>165°) and extremely low sliding angles (<2°). The conductivity is also percolation dominated, while the threshold for conductivity is much higher than that for superhydrophobicity, which can be ascribed to the encapsulated structure and the agglomeration of nanotubes in the composite coatings during air-spraying. Moreover, the aqueous silica sols hold merits of great film-forming capability at relatively low calcination temperatures, and being free of organic solvents.
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Nanoparticle and nanorod TiO2 composite photoelectrodes with improved performance.
Chem. Commun. (Camb.)
PUBLISHED: 05-16-2011
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A novel nanoparticle-nanorod composite TiO(2) photoelectrode is fabricated. A 3.20% efficiency is achieved by using a 2.1 ?m-thick as-prepared photoelectrode, which is about 3 times of that obtained by a nanorod array electrode (1.05%). The results demonstrate that the composite nanostructure can take advantage of both fast electron transport (nanorod) and high surface area (nanoparticle).
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Top-gated graphene field-effect transistors with high normalized transconductance and designable dirac point voltage.
ACS Nano
PUBLISHED: 05-06-2011
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High-performance graphene field-effect transistors (G-FETs) are fabricated with carrier mobility of up to 5400 cm(2)/V·s and top-gate efficiency of up to 120 (relative to that of back gate with 285 nm SiO(2)) simultaneously through growing high-quality Y(2)O(3) gate oxide at high oxidizing temperature. The transconductance normalized by dimension and drain voltage is found to reach 7900 ?F/V·s, which is among the largest of the published graphene FETs. In an as-fabricated graphene FET with a gate length of 310 nm, a peak transconductance of 0.69 mS/?m is realized, but further improvement is seriously hindered by large series resistance. Benefiting from highly efficient gate control over the graphene channel, the Dirac point voltage of the graphene FETs is shown to be designable via simply selecting a gate metal with an appropriate work function. It is demonstrated that the Dirac point voltage of the graphene FETs can be adjusted from negative to positive, respectively, via changing the gate material from Ti to Pd.
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Self-aligned U-gate carbon nanotube field-effect transistor with extremely small parasitic capacitance and drain-induced barrier lowering.
ACS Nano
PUBLISHED: 03-11-2011
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A novel self-aligned U-gate structure for carbon nanotube (CNT) field-effect transistors (FETs) is introduced and shown to yield excellent dc properties and high reproducibility that are comparable with that of the best CNT FETs based on the previously developed self-aligned device structures. In particular the subthreshold swing of the U-gate FET is 75 mV/dec and the drain-induced barrier lowering is effectively zero, indicating that the electrostatic potential of the whole CNT channel is most efficiently controlled by the U-gate and that the CNT device is a well-behaved FET. Moreover the high-frequency response of the U-gate FET is investigated, and the parasitic capacitance of the device is measured and shown to be one magnitude smaller than that of the previously developed self-aligned device structures. Direct frequency domain measurements show that the U-gate CNT FETs can operate up to 800 MHz, which is also higher than previously reported values. The large improvement in the device high-frequency behavior is largely due to the replacement of the high-? dielectric material between the source/drain and the gate by a vacant space with ? ? 1, and the significant reduction in the device parasitic capacitance renders the U-gate CNT FETs promising for rf applications.
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Quantum capacitance limited vertical scaling of graphene field-effect transistor.
ACS Nano
PUBLISHED: 02-16-2011
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A high-quality Y2O3 dielectric layer has been grown directly on graphene and used to fabricated top-gate graphene field-effect transistors (FETs), and the thickness of the dielectric layer has been reduced continuously down to 3.9 nm with an equivalent oxide thickness (EOT) of 1.5 nm and excellent insulativity. By measuring CV characteristics of two graphene FETs with different gate oxide thicknesses, the oxide capacitance and quantum capacitance are retrieved directly from the experimental CV data without introducing any additional fitting process and parameters, yielding a relative dielectric constant of ?=10 for Y2O3 on graphene and an oxide capacitance of about 2.28 ?F/cm2. It is found that for a rather large gate voltage range, this oxide capacitance is comparable and sometimes even larger than the quantum capacitance of graphene. Since the total gate capacitance is determined by the smaller of the oxide and quantum capacitance, our results show that not much further improvement can be gained via further vertical scaling down of the gate oxide, suggesting that Y2O3 may be the ultimate dielectric material for graphene. It is also shown that the Y2O3 gate dielectric layer with EOT of 1.5 nm may also satisfy the ultimate lateral scaling requirement on the gate length of graphene FET and be used effectively to control a graphene FET with a gate length as small as 1 nm.
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Fabrication and electric measurements of nanostructures inside transmission electron microscope.
Ultramicroscopy
PUBLISHED: 01-28-2011
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Using manipulation holders specially designed for transmission electron microscope (TEM), nanostructures can be characterized, measured, modified and even fabricated in-situ. In-situ TEM techniques not only enable real-time study of structure-property relationships of materials at atomic scale, but also provide the ability to control and manipulate materials and structures at nanoscale. This review highlights in-situ electric measurements and in-situ fabrication and structure modification using manipulation holder inside TEM.
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Spatially and angularly resolved cathodoluminescence study of single ZnO nanorods.
J Nanosci Nanotechnol
PUBLISHED: 12-09-2010
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Single ZnO nanorods were studied with cathodoluminescence at high spatial and angular resolution. A newly developed luminescence detector consisting a fiber probe controlled by a nano-manipulator is attached to a scanning electron microscope to carry out the cathodoluminescence measurements. Excitonic emission from the sidewalls and redshifted near band edge emission guided along the nanorod axis are observed as the fiber probe axis is aligned to be perpendicular and parallel to the nanorod axis, respectively, demonstrating the angular resolving power of the experimental setup and waveguiding behavior of the nanorods. High spatial resolution cathodoluminescence measurement shows that the near band edge emission can propagate parallel and perpendicular to the nanorod axis and an increased propagation distance results in more redshift of the guided luminescence. In addition, the high spatial resolution and temperature dependent cathodoluminescence measurements demonstrate the important role of free exciton-longitudinal optical phonon interaction in the waveguiding behavior and the propagation of the near band edge emission in ZnO nanorods.
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Thermoelectric measurement of multi-walled carbon nanotube bundles by using nano-probes.
J Nanosci Nanotechnol
PUBLISHED: 12-04-2010
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We report here a method for measurement of thermoelectric power of quasi-one dimensional nano-materials with a simple platform, where individual nanomaterial is assembled with nano-probes in a scanning electron microscope. This approach allows repeated manipulation and thermoelectric measurement of the same loaded nanosample with adjustable number of individual nanotubes or nanowires. It also allows assembly of multiple samples on one measurement stage. For multi-walled carbon nanotube bundles, we have observed a weak trend that, when the number of individual tubes in a bundle varies from ten millions to around a hundred thousand, the thermoelectric power almost remains at around 10 microV/K. When the tube number in the bundle is further reduced, the up-limit of the thermoelectric power gradually increases to a value near 20 microV/K.
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High-performance carbon nanotube light-emitting diodes with asymmetric contacts.
Nano Lett.
PUBLISHED: 11-30-2010
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Electroluminescence (EL) measurements are carried out on a two-terminal carbon nanotube (CNT) based light-emitting diode (LED). This two-terminal device is composed of an asymmetrically contacted semiconducting single-walled carbon nanotube (SWCNT). On the one end the SWCNT is contacted with Sc and on the other end with Pd. At large forward bias, with the Sc contact being grounded, electrons can be injected barrier-free into the conduction band of the SWCNT from the Sc contact and holes be injected into the valence band from the Pd electrode. The injected electrons and holes recombine radiatively in the SWCNT channel yielding a narrowly peaked emission peak with a full width at half-maximum of about 30 meV. Detailed EL spectroscopy measurements show that the emission is excitons dominated process, showing little overlap with that associated with the continuum states. The performance of the LED is compared with that based on a three-terminal field-effect transistor (FET) that is fabricated on the same SWCNT. The conversion efficiency of the two-terminal diode is shown to be more than three times higher than that of the FET based device, and the emission peak of the LED is much narrower and operation voltage is lower.
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Yeast deubiquitinase Ubp3 interacts with the 26 S proteasome to facilitate Rad4 degradation.
J. Biol. Chem.
PUBLISHED: 09-27-2010
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Deubiquitinating enzymes (DUBs) function in a variety of cellular processes by removing ubiquitin moieties from substrates, but their role in DNA repair has not been elucidated. Yeast Rad4-Rad23 heterodimer is responsible for recognizing DNA damage in nucleotide excision repair (NER). Rad4 binds to UV damage directly while Rad23 stabilizes Rad4 from proteasomal degradation. Here, we show that disruption of yeast deubiquitinase UBP3 leads to enhanced UV resistance, increased repair of UV damage and Rad4 levels in rad23? cells, and elevated Rad4 stability. A catalytically inactive Ubp3 (Ubp3-C469A), however, is unable to affect NER or Rad4. Consistent with its role in down-regulating Rad4, Ubp3 physically interacts with Rad4 and the proteasome, both in vivo and in vitro, suggesting that Ubp3 associates with the proteasome to facilitate Rad4 degradation and thus suppresses NER.
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Nonaligned carbon nanotubes partially embedded in polymer matrixes: a novel route to superhydrophobic conductive surfaces.
Langmuir
PUBLISHED: 08-11-2010
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A new method for transforming common polymers into superhydrophobic conductive surfaces, with both a high static water contact angle (approximately 160 degrees) and a low sliding angle (2.0 degrees-4.5 degrees), and a low sheet resistance on the order of 10(1)-10(3) ohms/sq is presented. A layer of multiwalled carbon nanotubes (MWNTs) is first distributed on the surface of a polymer substrate, then by a single step of pressing, the MWNTs are partially embedded inside the substrate surface and form a superhydrophobic coating with a "carpet-" or "hair"-like morphology. The infiltration of polymer melts into the porous MWNT layer follows Darcys law, and the pressing time greatly influence the morphology and superhydrophobicity. Moreover, the coating can be electrically heated by 20-70 degrees C with a voltage as low as 4-8 V at an electric energy density below 1.6 J/cm(2) and therefore can be used for deicing applications. Hydroxylation and fluoroalkylsilane treatment can greatly improve the stability of the superhydrophobicity of MWNTs. This method is convenient and applicable to a variety of thermoplastic polymers and nonpolymer substrates coated by silicone rubber.
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Carbon nanotubes noncovalently functionalized by an organic-inorganic hybrid: new building blocks for constructing superhydrophobic conductive coatings.
Langmuir
PUBLISHED: 08-11-2010
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A facile method for constructing superhydrophobic, conductive, and transparent/translucent coatings is presented. Pristine multiwalled carbon nanotubes (MWNTs) are first noncovalently (wrapped) modified by an organic-inorganic hybrid of an amphiphilic copolymer of styrene and maleic anhydride and silica with the existence of gamma-aminopropyltriethoxysilane (a silane coupling agent). The modified MWNTs were mixed with tetraethyl orthosilicate in ethanol, air sprayed, coated with a fluoroalkylsilane, and then heat treated to obtain the superhydrophobic, conductive, and transparent/translucent coatings. Scanning electron microscopy shows that the coatings have a micrometer- and nanometer-scale hierarchical structure similar to that of lotus leaves; therefore, they show both high water contact angles (>160 degrees) and low sliding angles (<2 degrees). The coatings also exhibit good transmittance and greatly improved conductivities. This method is convenient, inexpensive, and easy to scale up. Moreover, it does not require any chemical modification of the MWNTs or use any harsh chemicals.
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Large signal operation of small band-gap carbon nanotube-based ambipolar transistor: a high-performance frequency doubler.
Nano Lett.
PUBLISHED: 08-04-2010
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A small band-gap carbon nanotube (SBG CNT) with a large diameter of 4 nm has been used to fabricate ambipolar field-effect transistors (FETs) with ultrahigh carrier mobility of more than 18 300 and 8300 cm(2)/V x s for holes and electrons, respectively. Using a top-gate device geometry with 12 nm HfO(2) being the gate oxide, the SBG CNT-based FET exhibits an almost perfect symmetric ambipolar transfer characteristic without any noticeable hysteresis, and a highly efficient frequency doubler is constructed based on this near perfect ambipolar FET. The SBG CNT-based frequency doubler is shown to be able to operate in a large signal mode where the input AC signal, being applied to the top-gate electrode, drives the FET operating alternatively in a p- or n-region yielding an output signal at the drain electrode with doubled frequency and high conversion efficiency. For an input AC signal of 1 kHz, detailed frequency power spectrum analysis shows that more than 95% of the output signal is concentrated at the doubled frequency at 2 kHz, with a gain of more than 0.15, and this represents the highest gain so far achieved in carbon-based devices, including graphene-based devices.
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Adsorption of EDTA on activated carbon from aqueous solutions.
J. Hazard. Mater.
PUBLISHED: 07-10-2010
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In this study, the adsorption of EDTA on activated carbon from aqueous solutions has been investigated in a batch stirred cell. Experiments have been carried out to investigate the effects of temperature, EDTA concentration, pH, activated carbon mass and particle size on EDTA adsorption. The experimental results manifest that the EDTA adsorption rate increases with its concentration in the aqueous solutions. EDTA adsorption also increases with temperature. The EDTA removal from the solution increases as activated carbon mass increases. The Langmuir and Freundlich equilibrium isotherm models are found to provide a good fitting of the adsorption data, with R(2) = 0.9920 and 0.9982, respectively. The kinetic study shows that EDTA adsorption on the activated carbon is in good compliance with the pseudo-second-order kinetic model. The thermodynamic parameters (E(a), ?G(0), ?H(0), ?S(0)) obtained indicate the endothermic nature of EDTA adsorption on activated carbon.
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Growth and performance of yttrium oxide as an ideal high-kappa gate dielectric for carbon-based electronics.
Nano Lett.
PUBLISHED: 05-12-2010
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High-quality yttrium oxide (Y(2)O(3)) is investigated as an ideal high-kappa gate dielectric for carbon-based electronics through a simple and cheap process. Utilizing the excellent wetting behavior of yttrium on sp(2) carbon framework, ultrathin (about few nm) and uniform Y(2)O(3) layers have been directly grown on the surfaces of carbon nanotube (CNT) and graphene without using noncovalent functionalization layers or introducing large structural distortion and damage. A top-gate CNT field-effect transistor (FET) adopting 5 nm Y(2)O(3) layer as its top-gate dielectric shows excellent device characteristics, including an ideal subthreshold swing of 60 mV/decade (up to the theoretical limit of an ideal FET at room temperature). The high electrical quality Y(2)O(3) dielectric layer has also been integrated into a graphene FET as its top-gate dielectric with a capacitance of up to 1200 nF/cm(2), showing an improvement on the gate efficiency and on state transconductance of over 100 times when compared with that of its back-gate counterpart.
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Y-contacted high-performance n-type single-walled carbon nanotube field-effect transistors: scaling and comparison with Sc-contacted devices.
Nano Lett.
PUBLISHED: 12-10-2009
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While it has been shown that scandium (Sc) can be used for making high-quality Ohmic contact to the conduction band of a carbon nanotube (CNT) and thus for fabricating high-performance n-type CNT field effect transistors (FETs), the cost for metal Sc is currently five times more expensive than that for gold and one thousand times more expensive than for yttrium (Y) which in many ways resembles Sc. In this Letter we show that near perfect contacts can be fabricated on single-walled CNTs (SWCNTs) using Y, and the Y-contacted CNT FETs outperform the Sc-contacted CNT FETs in many important aspects. Low-temperature measurements on Y-contacted devices reveal that linear output characteristics persist down to 4.3 K, suggesting that Y makes a perfect Ohmic contact with the conduction band of the CNT. Self-aligned top-gate devices have been fabricated, showing high performance approaching the theoretical limit of CNT-based devices. In particular a room temperature conductance of about 0.55G(0) (with G(0) = 4e(2)/h being the quantum conductance limit of the SWCNT), threshold swing of 73 mV/decade, electron mobility of 5100 cm(2)/V.s, and mean free length of up to 0.639 mum have been achieved. Gate length scaling behavior of the Y-contacted CNT FETs is also investigated, revealing a more favorable energy consumption and faster intrinsic speed scaling than that of the Si-based devices.
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Surface-initiated graft polymerization on multiwalled carbon nanotubes pretreated by corona discharge at atmospheric pressure.
Nanoscale
PUBLISHED: 11-24-2009
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Surface-initiated graft polymerization on multi-walled carbon nanotubes pretreated with a corona discharge at atmospheric pressure was explored. The mechanism of the corona-discharge-induced graft polymerization is discussed. The results indicate that MWCNTs were encapsulated by poly(glycidyl methacrylate) (PGMA), demonstrating the formation of PGMA-grafted MWCNTs (PGMA-g-MWCNTs), with a grafting ratio of about 22 wt%. The solubility of PGMA-g-MWCNTs in ethanol was dramatically improved compared to pristine MWCNTs, which could contribute to fabricating high-performance polymer/MWCNTs nanocomposites in the future. Compared with most plasma processes, which operate at low pressures, corona discharge has the merit of working at atmospheric pressure.
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Almost perfectly symmetric SWCNT-based CMOS devices and scaling.
ACS Nano
PUBLISHED: 10-23-2009
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Symmetric n- and p-type field-effect transistors (FETs) have been fabricated on the same undoped single-walled carbon nanotube (SWCNT). The polarity of the FET is defined by controlled injection of electrons (n-type, via Sc electrodes) or holes (p-type, via Pd electrodes) into the SWCNT, instead of via chemically doping the SWCNT. The SWCNT-based FETs with different channel lengths show a clear trend of performance improvement for channel length scaling. Taking full advantage of the perfect symmetric band structure of the semiconductor SWCNT, a perfect SWCNT-based CMOS inverter is demonstrated, which gives a voltage gain of over 160, and for the two adjacent n- and p-type FETs fabricated on the same SWCNT, high field mobility is realized simultaneously for electrons (3000 cm(2)/V.s) and holes (3300 cm(2)/V.s).
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Transmission electron microscope observation of a freestanding nanocrystal in a Coulomb potential well.
Nanoscale
PUBLISHED: 10-21-2009
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Usually pure electrostatic charges cannot be utilized alone to form macro-sized three-dimensional electromagnetic traps for trapping charged particles. These traps need additional dynamic electromagnetic fields. We report here the observation of a CdSe nanocrystal floating over a carbon film in a transmission electron microscope. The nanocrystal was most likely trapped in a naturally formed, nanometre-sized 3D Coulomb potential well. The results indicated the possibility of developing a novel nanodevice for the trapping and manipulation of charged nanoparticles.
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Path-folded infrared spectrometer consisting of 10 sub-gratings and a two-dimensional InGaAs detector.
Opt Express
PUBLISHED: 08-19-2009
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A new compact infrared spectrometer without any mechanical moving elements has been designed and constructed using a two-dimensional InGaAs array detector and 10 sub-gratings. The instrument is compact, with a double-folded optical path configuration. The spectra are densely 10-folded to achieve 0.07-nm spectral resolution and a 2-ms data acquisition time in the 1450- to 1650-nm wavelength region, making the instrument useful for real-time spectroscopic data analyses in optical communication and many other fields.
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Spectral study of interaction between poly [acrylamide-(2-methyl acryloxyethyl) dimethyl buthylammonium bromide] and nucleic acids.
Luminescence
PUBLISHED: 06-04-2009
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A polycation, poly[acrylamide-(2-methylacryloxyethyl) dimethyl buthylammonium bromide] [P (AM-DMB)], was synthesized. The interaction between P (AM-DMB) and DNA was studied by spectral methods. Resonance light scattering spectra, FTIR-spectra and UV-spectra were used to study the mechanisms of the interaction. The results indicate that the conformation of the DNA alters during the interaction because the microenvironment of DNA changes. The binding constant K between P (AM-DMB) and DNA is 8.0 × 10(3) ?L?mol(-1) .
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Preparation and mechanical properties of carbon fiber reinforced hydroxyapatite/polylactide biocomposites.
J Mater Sci Mater Med
PUBLISHED: 05-18-2009
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A novel biocomposite of carbon fiber (CF) reinforced hydroxyapatite (HA)/polylactide (PLA) was prepared by hot pressing a prepreg which consisting of PLA, HA and CF. The prepreg was manufactured by solvent impregnation process. Polymer resin PLA dissolved with chloroform was mixed with HA. After reinforcement CF bundle was impregnated in the mixture, the solvent was dried completely and subsequently hot-pressed uniaxially under a pressure of 40 MPa at 170 degrees C for 20 min. A study was carried out to investigate change in mechanical properties of CF/HA/PLA composites before and after degradation in vitro. The composites have excellent mechanical properties. A peak showed in flexural strength, flexural modulus and shear strength aspects, reaching up 430 MPa, 22 GPa, 212 MPa, respectively, as the HA content increased. Degraded in vitro for 3 months, the flexural strength and flexural modulus of the CF/HA/PLA fell 13.2% and 5.4%, respectively, while the shear strength of the CF/HA/PLA composites remains at the 190 MPa level. The SEM photos showed that there were gaps between the PLA matrix and CF after degradation. Water uptake increased to 5%, but the mass loss rate was only 1.6%. The pH values of the PBS dropped less than 0.1. Thats because the alkaline of HA neutralize the acid degrades from PLA, which can prevent the body from the acidity harm.
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Study of the new ellipsometric measurement method using integrated analyzer in parallel mode.
Opt Express
PUBLISHED: 05-13-2009
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A new type of ellipsometer using an integrated analyzer composed of 12 sub-analyzers with different azimuth angles was constructed and studied. By using a two-dimensional CCD array camera to measure the light intensity emerging in parallel from each sub-analyzer with the azimuth angles uniformly distributed in the range of about 180 degrees , the ellipsometric parameters were extracted within the data acquisition time less than 1 second. The ellipsometric parameters for the polished bulk Si sample were measured to show good agreement with the results measured by using another two ellipsometric methods. The new method having the merits of high speed and reliability in the optical data measurement can be potentially used in the fields where the in situ data acquisition with high precision is the key issue as required.
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In situ comprehensive characterization of optoelectronic nanomaterials for device purposes.
Nanotechnology
PUBLISHED: 04-03-2009
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We have combined optical fiber probe and nanoprobe techniques in a scanning electron microscope, which enables in situ optical, electrical and structural characterization of optoelectronic nanomaterials and nanodevices. The nanoprobe technique, employing sharp metal tips, is used for in situ nano-manipulation, contact and electrical measurement. The fiber probe, coupled to a spectrometer or a laser and controlled by a nano-manipulator, allows local optical detection or excitation. We show in situ assembly of a light emitter and photodetector based on individual nanostructures, demonstrating the potential application of the above technique in building prototype optoelectronic devices and selecting suitable nanostructures for device purposes. In addition, the angular resolving power of the fiber probe detection is demonstrated to be useful for studying nanoscale waveguides.
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Experimental determination of equilibrium constant for the complexing reaction of nitric oxide with hexamminecobalt(II) in aqueous solution.
J. Hazard. Mater.
PUBLISHED: 04-03-2009
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Ammonia solution can be used to scrub NO from the flue gases by adding soluble cobalt(II) salts into the aqueous ammonia solutions. The hexamminecobalt(II), Co(NH3)6(2+), formed by ammonia binding with Co2+ is the active constituent of eliminating NO from the flue gas streams. The hexamminecobalt(II) can combine with NO to form a complex. For the development of this process, the data of the equilibrium constants for the coordination between NO and Co(NH3)6(2+)over a range of temperature is very important. Therefore, a series of experiments were performed in a bubble column to investigate the chemical equilibrium. The equilibrium constant was determined in the temperature range of 30.0-80.0 degrees C under atmospheric pressure at pH 9.14. All experimental data fit the following equation well: [see text] where the enthalpy and entropy are DeltaH degrees = - (44.559 +/- 2.329)kJ mol(-1) and DeltaS degrees = - (109.50 +/- 7.126) J K(-1)mol(-1), respectively.
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Molecular characterization of Fasciola hepatica, Fasciola gigantica, and aspermic Fasciola sp. in China based on nuclear and mitochondrial DNA.
Parasitol. Res.
PUBLISHED: 03-12-2009
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Parthenogenic Fasciola forms as well as bisexual Fasciola hepatica and Fasciola gigantica in mainland China have been identified on the basis of their spermatogenesis and genotypes in nuclear ribosomal internal transcribed spacer 1 (ITS1) and mitochondrial NADH dehydrogenase I (NDI). The Chinese aspermic Fasciola would include forms originating in interspecific hybrids between F. hepatica and F. gigantica, since they showed the genotype of ITS1-Fh/Fg that had mixed sequences of the two Fasciola species or heterogeneous genotypes in ITS1 and NDI. Additionally, there were Chinese aspermic flukes in which the sequences of ITS1 and NDI genotypes completely coincided with those in aspermic forms from Japan, Korea, and Vietnam, suggesting that the aspermic forms from these four countries are offspring with a common provenance. The Fh-C4 haplotype in NDI was detected in both aspermic specimens and F. hepatica, indicating that aspermic forms showing the haplotype might come into existence in China. The ratio of body length and width in aspermic Fasciola specimens showed intermediate values between those of F. hepatica and F. gigantica.
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Sys-BodyFluid: a systematical database for human body fluid proteome research.
Nucleic Acids Res.
PUBLISHED: 03-04-2009
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Recently, body fluids have widely become an important target for proteomic research and proteomic study has produced more and more body fluid related protein data. A database is needed to collect and analyze these proteome data. Thus, we developed this web-based body fluid proteome database Sys-BodyFluid. It contains eleven kinds of body fluid proteomes, including plasma/serum, urine, cerebrospinal fluid, saliva, bronchoalveolar lavage fluid, synovial fluid, nipple aspirate fluid, tear fluid, seminal fluid, human milk and amniotic fluid. Over 10,000 proteins are presented in the Sys-BodyFluid. Sys-BodyFluid provides the detailed protein annotations, including protein description, Gene Ontology, domain information, protein sequence and involved pathways. These proteome data can be retrieved by using protein name, protein accession number and sequence similarity. In addition, users can query between these different body fluids to get the different proteins identification information. Sys-BodyFluid database can facilitate the body fluid proteomics and disease proteomics research as a reference database. It is available at http://www.biosino.org/bodyfluid/.
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Effects of reactive compatibilization on the morphological, thermal, mechanical, and rheological properties of intumescent flame-retardant polypropylene.
ACS Appl Mater Interfaces
PUBLISHED: 02-25-2009
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Flame-retardant polypropylene (PP) samples were in situ compatibilized with maleic anhydride grafted PP. Compatibilization reaction was verified by an IR spectrum and gel content measurements. Electron microscopy images showed that compatibilization could considerably reduce the size of the flame-retardant domains, control the phase morphology, and improve the interfacial adhesion between PP and intumescent flame retardant (IFR) with different IFR loading levels. The limiting oxygen index (LOI) of flame-retardant PP increased to different extents after compatibilization, indicating an improvement in the flame retardancy. Compatibilization enhanced the thermal stability to some extent and remarkably delayed thermal oxidative degradation of flame-retardant PP. For PP containing 20 wt % flame retardant, the temperature at which the maximum weight loss rate occurred was enhanced by about 99 degrees C after compatibilization. The storage modulus and glass transition temperatures were elevated to different extents. Tensile strengths of samples reduced in the presence of flame retardant alone but in the additional presence of compatibilizer were restored to levels similar to those of pure PP. Elongation-at-break values, however, showed IFR concentration-dependent reductions that were less for compatibilized samples. Furthermore, the complex viscosity of a compatibilized PP melt turned slightly smaller, which is favorable to melt processing.
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[Pedicle screw at the fracture level and vertebroplasty via paraspinal approach for the treatment of old thoracolumbar fractures].
Zhongguo Gu Shang
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To investigate the feasibility and safety of the treatment for thoracolumbar fractures with pedicle screw at the fracture level and vertebroplasty via paraspinal approach.
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[Comparison of botanical characteristics of cultivated Chrysanthemum morifolium cv. Hangju of different origins].
Zhongguo Zhong Yao Za Zhi
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To compare botanical characteristics of cultivated Chrysanthemum morifolium cv. Hangju of different origins in order to provide the basis for introduction and cultivation of Ch. morifolium cv. Hangju.
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[Surgical treatment of thoracolumbar fractures using reduction and short-segment pedicle screw at the fracture level with the approach through para-vertebral muscles].
Zhongguo Gu Shang
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To evaluate the efficacy and clinical outcome of reduction and pedicle screws fixation at the fracture level with the approach through para-vertebral muscles in treating thoraeolumbar fractures.
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Toward a comprehensive characterization of a human cancer cell phosphoproteome.
J. Proteome Res.
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Mass spectrometry (MS)-based phosphoproteomics has achieved extraordinary success in qualitative and quantitative analysis of cellular protein phosphorylation. Considering that an estimated level of phosphorylation in a cell is placed at well above 100,000 sites, there is still much room for improvement. Here, we attempt to extend the depth of phosphoproteome coverage while maintaining realistic aspirations in terms of available material, robustness, and instrument running time. We developed three strategies, where each provided a different balance between these three key parameters. The first strategy simply used enrichment by Ti(4+)-IMAC followed by reversed chromatography LC-MS (termed 1D). The second strategy incorporated an additional fractionation step through the use of HILIC (2D). Finally, a third strategy was designed employing first an SCX fractionation, followed by Ti(4+)-IMAC enrichment and additional fractionation by HILIC (3D). A preliminary evaluation was performed on the HeLa cell line. Detecting 3700 phosphopeptides in about 2 h, the 1D strategy was found to be the most sensitive but limited in comprehensivity, mainly due to issues with complexity and dynamic range. Overall, the best balance was achieved using the 2D based strategy, identifying close to 17,000 phosphopeptides with less than 1 mg of material in about 48 h. Subsequently, we confirmed the findings with the K562 cell sample. When sufficient material was available, the 3D strategy increased phosphoproteome allowing over 22,000 unique phosphopeptides to be identified. Unfortunately, the 3D strategy required more time and over 1 mg of material before it started to outperform 2D. Ultimately, combining all strategies, we were able to identify over 16,000 and nearly 24,000 unique phosphorylation sites from the cancer cell lines HeLa and K562, respectively. In summary, we demonstrate the need to carry out extensive fractionation for deep mining of the phosphoproteome and provide a guide for appropriate strategies depending on sample amount and/or analysis time.
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The Emerging Roles of ATP-Dependent Chromatin Remodeling Enzymes in Nucleotide Excision Repair.
Int J Mol Sci
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DNA repair in eukaryotic cells takes place in the context of chromatin, where DNA, including damaged DNA, is tightly packed into nucleosomes and higher order chromatin structures. Chromatin intrinsically restricts accessibility of DNA repair proteins to the damaged DNA and impacts upon the overall rate of DNA repair. Chromatin is highly responsive to DNA damage and undergoes specific remodeling to facilitate DNA repair. How damaged DNA is accessed, repaired and restored to the original chromatin state, and how chromatin remodeling coordinates these processes in vivo, remains largely unknown. ATP-dependent chromatin remodelers (ACRs) are the master regulators of chromatin structure and dynamics. Conserved from yeast to humans, ACRs utilize the energy of ATP to reorganize packing of chromatin and control DNA accessibility by sliding, ejecting or restructuring nucleosomes. Several studies have demonstrated that ATP-dependent remodeling activity of ACRs plays important roles in coordination of spatio-temporal steps of different DNA repair pathways in chromatin. This review focuses on the role of ACRs in regulation of various aspects of nucleotide excision repair (NER) in the context of chromatin. We discuss current understanding of ATP-dependent chromatin remodeling by various subfamilies of remodelers and regulation of the NER pathway in vivo.
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Model GW study of the late transition metal monoxides.
J Chem Phys
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The model GW method [F. Gygi and A. Baldereschi, Phys. Rev. Lett. 62, 2160 (1989)] is an efficient simplification to the standard GW approximation which uses model dielectric function to describe the long range Coulomb interactions in semiconductors. In this work, the model GW method is used to calculate the quasiparticle band structures of MnO, FeO, CoO, and NiO. All four late transition metal monoxides are predicted to be insulators. The band gaps, magnetic moments, and quasiparticle spectra are in good agreement with the experiments, except for the satellite structures which are missing in the density of states because the model GW self-energy is static. The high accuracy of model GW is due to the usage of the accurate dielectric constants in the construction of the model dielectric functions which ensures the correct asymptotic behavior of the long range Coulomb interactions. Besides, we find that the transition metal 4s states are irrelevant to the formation of the band gaps, which supports the local approaches and the experimental interpretations of the band gaps by photoemission and electron energy loss spectroscopy, while contradicts the recent calculations by hybrid functionals, exact exchange, and one shot GW approximations.
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Pointwise plucking of suspended carbon nanotubes.
Nano Lett.
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Vibration of nanotubes/wires is significant for fundamental and applied researches. However, it remains challenging to control the vibration with point-level precision. Herein, individual suspended carbon nanotubes are plucked point by point to vibrate in scanning electron microscope with the electron beam as a nanoscale pointer. The vibration is directly imaged, and its images fit well with simulations from the plucking mechanism. This demonstrates a new way to manipulate the nanotube vibration with unprecedented precision.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.