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Find video protocols related to scientific articles indexed in Pubmed.
Reliable control of filament formation in resistive memories by self-assembled nanoinsulators derived from a block copolymer.
ACS Nano
PUBLISHED: 09-11-2014
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Resistive random access memory (ReRAM) is a promising candidate for future nonvolatile memories. Resistive switching in a metal-insulator-metal structure is generally assumed to be caused by the formation/rupture of nanoscale conductive filaments (CFs) under an applied electric field. The critical issue of ReRAM for practical memory applications, however, is insufficient repeatability of the operating voltage and resistance ratio. Here, we present an innovative approach to reliably and reproducibly control the CF growth in unipolar NiO resistive memory by exploiting uniform formation of insulating SiOx nanostructures from the self-assembly of a Si-containing block copolymer. In this way, the standard deviation (SD) of set and reset voltages was markedly reduced by 76.9% and 59.4%, respectively. The SD of high resistance state also decreased significantly, from 6.3 × 10(7) ? to 5.4 × 10(4) ?. Moreover, we report direct observations of localized metallic Ni CF formation and their controllable growth using electron microscopy and discuss electrothermal simulation results based on the finite element method supporting our analysis results.
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Metabolism of Rutin and Poncirin by Human Intestinal Microbiota and Cloning of Their Metabolizing ?-L-Rhamnosidase from Bifidobacterium dentium.
J. Microbiol. Biotechnol.
PUBLISHED: 09-01-2014
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To understand the metabolism of flavonoid rhamnoglycosides by human intestinal microbiota, we measured the metabolic activity of rutin and poncirin distributed in many functional foods and herbal medicine by 100 human stool specimens. The average ?-L-rhamnosidase activities on the p-nitrophenyl-?-L-rhamnopyranoside, rutin and poncirin subtrates were 0.10 ± 0.07, 0.25 ± 0.08 and 0.15 ± 0.09 pmol/min/mg, respectively. To investigate the enzymatic properties, ?-L-rhamnosidase-producing bacteria were isolated from the specimens, and the ?-L-rhamnosidase gene was cloned from a selected organism, Bifidobacterium dentium K13, and expressed in E. coli. The cloned ?-L-rhamnosidase gene contains 2,673bp sequcence encoding 890 amino acid residues. The cloned gene was expressed using the pET 26b(+) vector in E. coli BL21, and the expressed enzyme was purified using Ni2+-NTA and Q-HP column chromatography. Specific activity of purified ?-L-rhamnosidase was 23.3 ?mol/min/mg. Of tested natural product constituents, the cloned ?-L-rhamnosidase hydrolyzed rutin most potently, followed by poncirin, naringin, and ginsenoside Re. However, it was unable to hydrolyze quercitrin. This is the first report describing the cloning, expression and characterization of ?-L-rhamnosidase, a flavonoid rhamnoglycoside-metabolizing enzyme, from Bifidobacteria. Based on these findings, the ?-L-rhamnosidase of intestinal bacteria such as B. dentium K13 seem to be more effective in hydrolyzing (1-->6) bonds than (1-->2) bonds of rhamnoglycosides and may play an important role in the metabolism and pharmacological effect of rhamnoglycosides.
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Screening and characterization of a novel cellulase gene from the gut microflora of Hermetia illucens using metagenomic library.
J. Microbiol. Biotechnol.
PUBLISHED: 07-16-2014
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A metagenomic fosmid library was constructed using genomic DNA isolated from the gut microflora of Hermetia illucens, a black soldier fly. A cellulase-positive clone, with the CS10 gene, was identified by extensive Congo-red overlay screenings for cellulase activity from the fosmid library of 92,000 clones. The CS10 gene was composed of a 996 bp DNA sequence encoding the mature protein of 331 amino acids. The deduced amino acids of CS10 showed 72% sequence identity with the glycosyl hydrolase family 5 gene of Dysgonomonas mossii, displaying no significant sequence homology to already known cellulases. The purified CS10 protein presented a single band of cellulase activity with a molecular mass of approximately 40 kDa on the SDS-PAGE gel and zymogram. The purified CS10 protein exhibited optimal activity at 50°C and pH 7.0, and the thermostability and pH stability of CS10 were preserved at the ranges of 20~50°C and pH 4.0~10.0. CS10 exhibited little loss of cellulase activity against various chemical reagents such as 10% polar organic solvents, 1% non-ionic detergents, and 0.5 M denaturing agents. Moreover, the substrate specificity and the product patterns by thinlayer chromatography suggested that CS10 is an endo-?-1,4-glucanase. From these biochemical properties of CS10, it is expected that the enzyme has the potential for application in industrial processes.
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Anisotropic lithiation onset in silicon nanoparticle anode revealed by in situ graphene liquid cell electron microscopy.
ACS Nano
PUBLISHED: 07-07-2014
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Recent real-time analyses have provided invaluable information on the volume expansion of silicon (Si) nanomaterials during their electrochemical reactions with lithium ions and have thus served as useful bases for robust design of high capacity Si anodes in lithium ion batteries (LIBs). In an effort to deepen the understanding on the critical first lithiation of Si, especially in realistic liquid environments, herein, we have engaged in situ graphene liquid cell transmission electron microscopy (GLC-TEM). In this technique, chemical lithiation is stimulated by electron-beam irradiation, while the lithiation process is being monitored by TEM in real time. The real-time analyses informing of the changes in the dimensions and diffraction intensity indicate that the very first lithiation of Si nanoparticle shows anisotropic volume expansion favoring the ?110? directions due to the smaller Li diffusion energy barrier at the Si-electrolyte interface along such directions. Once passing this initial volume expansion stage, however, Li diffusion rate becomes isotropic in the inner region of the Si nanoparticle. The current study suggests that the in situ GLC-TEM technique can be a useful tool in understanding battery reactions of various active materials, particularly those whose initial lithiation plays a pivotal role in overall electrochemical performance and structural stability of the active materials.
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Lissajous fiber scanning for forward viewing optical endomicroscopy using asymmetric stiffness modulation.
Opt Express
PUBLISHED: 03-26-2014
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We report a fully packaged and compact forward viewing endomicroscope by using a resonant fiber scanner with two dimensional Lissajous trajectories. The fiber scanner comprises a single mode fiber with additional microstructures mounted inside a piezoelectric tube with quartered electrodes. The mechanical cross-coupling between the transverse axes of a resonant fiber with a circular cross-section was completely eliminated by asymmetrically modulating the stiffness of the fiber cantilever with silicon microstructures and an off-set fiber fragment. The Lissajous fiber scanner was fully packaged as endomicroscopic catheter passing through the accessory channel of a clinical endoscope and combined with spectral domain optical coherence tomography (SD-OCT). Ex-vivo 3D OCT images were successfully reconstructed along Lissajous trajectory. The preview imaging capability of the Lissajous scanning enables rapid 3D imaging with high temporal resolution. This endoscopic catheter provides many opportunities for on-demand and non-invasive optical biopsy inside a gastrointestinal endoscope.
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Perfluorinated alkyl substances in water, sediment, plankton and fish from Korean rivers and lakes: a nationwide survey.
Sci. Total Environ.
PUBLISHED: 01-10-2014
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Water, sediment, plankton, and blood and liver tissues of crucian carp (Carassius auratus) and mandarin fish (Siniperca scherzeri) were collected from six major rivers and lakes in South Korea (including Namhan River, Bukhan River, Nakdong River, Nam River, Yeongsan River and Sangsa Lake) and analyzed for perfluorinated alkyl substances (PFASs). Perfluorooctane sulfonate (PFOS) was consistently detected at the greatest concentrations in all media surveyed with the maximum concentration in water of 15 ng L(-1) and in biota of 234 ng mL(-1) (fish blood). A general ascending order of PFAS concentration of water0.80, p<0.001) were observed between PFOS concentration in blood and liver tissues of both crucian carp and mandarin fish. This result suggests that blood can be used for nonlethal monitoring of PFOS in fish. Overall, the rank order of mean bioconcentration factors (BCFs) of PFOS in biota was; phytoplankton (196 L/kg)
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Computational study on subdural cortical stimulation - the influence of the head geometry, anisotropic conductivity, and electrode configuration.
PLoS ONE
PUBLISHED: 01-01-2014
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Subdural cortical stimulation (SuCS) is a method used to inject electrical current through electrodes beneath the dura mater, and is known to be useful in treating brain disorders. However, precisely how SuCS must be applied to yield the most effective results has rarely been investigated. For this purpose, we developed a three-dimensional computational model that represents an anatomically realistic brain model including an upper chest. With this computational model, we investigated the influence of stimulation amplitudes, electrode configurations (single or paddle-array), and white matter conductivities (isotropy or anisotropy). Further, the effects of stimulation were compared with two other computational models, including an anatomically realistic brain-only model and the simplified extruded slab model representing the precentral gyrus area. The results of voltage stimulation suggested that there was a synergistic effect with the paddle-array due to the use of multiple electrodes; however, a single electrode was more efficient with current stimulation. The conventional model (simplified extruded slab) far overestimated the effects of stimulation with both voltage and current by comparison to our proposed realistic upper body model. However, the realistic upper body and full brain-only models demonstrated similar stimulation effects. In our investigation of the influence of anisotropic conductivity, model with a fixed ratio (1?10) anisotropic conductivity yielded deeper penetration depths and larger extents of stimulation than others. However, isotropic and anisotropic models with fixed ratios (1?2, 1?5) yielded similar stimulation effects. Lastly, whether the reference electrode was located on the right or left chest had no substantial effects on stimulation.
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In situ atomic imaging of coalescence of Au nanoparticles on graphene: rotation and grain boundary migration.
Chem. Commun. (Camb.)
PUBLISHED: 10-15-2013
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Using in situ transmission electron microscopy, we demonstrated that gold nanoparticles are unified via "oriented attachment" assisted either by nanoparticle rotation or grain boundary migration at the attachment interface. We also observed that the combined nanoparticle changes shape with stable facet planes via surface diffusion, along with recrystallization.
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Comparison of neuronal excitation between extruded slab partial head model and full head model in subdural cortical stimulation.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 10-11-2013
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Cortical stimulation (CS) is an appealing and emerging treatment for neurological disorders. CS is known to promote functional recovery effectively; however, its underlying mechanism and the optimal parameters for the effective treatment are not clearly understood. In this work, we developed a realistic three-dimensional full head and chest model for subdural CS. Our proposed model was compared at the neuron level with an existing simplified extruded slab partial head model depicting around precentral gyral cortex only. Each model was coupled with the pyramidal neuronal model in order to investigate an extent of neuronal excitation. We found that the crown of the cortex was the most excitable area in the unipolar stimulation, while in the bipolar stimulation, the lip and bank were excited more easily than other areas. Finally, it was evident that our proposed model was substantially different in excitation threshold from the existing simplified model, which is compelling to do computational CS study on more realistic head models.
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Bilateral asymmetry in microarchitecture of trabecular bone in male C57BL/6 mouse tibia: implication for experimental sample size estimations.
Proc Inst Mech Eng H
PUBLISHED: 04-18-2013
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This study aimed to determine whether there is bilateral asymmetry between the left and right tibiae in the microarchitectural characteristics of the trabecular bone and estimate a moderate sample size for detections of such bilateral differences. The left and right tibiae of 20 C57BL/6 mice (12 weeks old) were scanned by micro-computed tomography, and the structural parameters of the trabecular bone were measured. There were significant differences in the structural parameters between the left and right tibiae (p<0.05); specifically, the microarchitecture was greater in quantity and quality in the left tibia than in the right tibia. Moreover, the percent of bilateral differences between the left and right tibiae ranged from 2.26% to 22.52%. For most of the structural parameters except for trabecular bone thickness (Tb.Th) and trabecular bone separation (Tb.Sp), the 20 mice involved in this study were enough to detect differences. These results show that the directional left-right asymmetry in the microarchitecture of the trabecular bone may exist despite the samples being from an inbred strain. Furthermore, we estimated a sample size for detections of such differences between the left and right tibiae.
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Development of reproductive organs in the ivory shell Babylonia japonica: Observations from wild populations and laboratory-reared juveniles.
Mar. Environ. Res.
PUBLISHED: 03-31-2013
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We histologically examined normal differentiation and development of genital tract and gonad in the ivory shell Babylonia japonica (Buccinidae) to determine whether the formation of male-type genitalia in imposex-exhibiting females mimics the normal development of male genitalia in prosobranch gastropods. We used a wild-caught 2-year-old specimen and laboratory-reared juveniles aged 0-24 months. Gonad differentiation was unclear before age 14 months, but progressed after 16 months. Both sexes had complete genital tract and mature gonad at 20 months. However, differentiation and development occurred earlier in females than in males. Development of genital tract preceded gonad differentiation. Vas deferens morphogenesis in males resembled that in imposex-exhibiting females. These findings help to understand the morphogenesis of genital tract and gonad in prosobranch gastropods and will contribute to more in-depth studies of the mode of action of organotin compounds such as TBT and TPhT in imposex development in female prosobranch gastropods.
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Self-assembled incorporation of modulated block copolymer nanostructures in phase-change memory for switching power reduction.
ACS Nano
PUBLISHED: 03-11-2013
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Phase change memory (PCM), which exploits the phase change behavior of chalcogenide materials, affords tremendous advantages over conventional solid-state memory due to its nonvolatility, high speed, and scalability. However, high power consumption of PCM poses a critical challenge and has been the most significant obstacle to its widespread commercialization. Here, we present a novel approach based on the self-assembly of a block copolymer (BCP) to form a thin nanostructured SiOx layer that locally blocks the contact between a heater electrode and a phase change material. The writing current is decreased 5-fold (corresponding to a power reduction by 1/20) as the occupying area fraction of SiOx nanostructures is increased from a fill factor of 9.1% to 63.6%. Simulation results theoretically explain the current reduction mechanism by localized switching of BCP-blocked phase change materials.
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[The efficacy and tolerability of sugared polyethylene glycol for colonoscopy].
Korean J Gastroenterol
PUBLISHED: 03-06-2013
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Although polyethylene glycol (PEG) solution is commonly used for colonoscopic bowel preparation because of its safety and effectiveness, its salty taste decreases patients compliance. The aim of this study was to compare the sugared PEG solution with the standard PEG solution in regard to the quality of bowel preparation and patients compliance.
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A case of congenital hypertrophic cardiomyopathy.
Korean Circ J
PUBLISHED: 01-31-2013
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Congenital hypertrophic cardiomyopathy (HCMP) is a very rare congenital heart disease. Here, we report a case of neonatal HCMP, which was confirmed by two-dimensional echocardiography and autopsy. The HCMP rapidly progressed and the patients condition deteriorated, despite the treatment for congestive heart failure.
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Anti-cancer effect of HS-345, a new tropomyosin-related kinase A inhibitor, on human pancreatic cancer.
Cancer Lett.
PUBLISHED: 01-15-2013
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Tropomyosin-related kinase A (TrkA) is emerging as an important player in carcinogenic progression. TrkA overexpression, which is associated with cell growth, proliferation, survival, and invasion, has been observed in pancreatic cancer. We therefore synthesized HS-345, a novel TrkA inhibitor, and evaluated its anti-cancer effect and underlying mechanism of action in pancreatic cancer. In this study, HS-345 effectively inhibited the growth and proliferation in three pancreatic cancer cell lines (PANC-1, MIA PaCa-2, and BxPC-3). Activation of the TrkA/Akt signal cascade was also inhibited by HS-345 treatment in a dose-dependent manner. The pro-apoptotic effect of HS-345 was evidenced by increased levels of cleaved caspase-3 and cleaved PARP, and decrease of Bcl/Bax expression via mitochondria membrane potential, as well as elevated numbers of TUNEL-positive apoptotic cells. HS-345 was additionally found to exert anti-angiogenic effect by decreasing the expression of HIF-1? and VEGF, major factors of angiogenesis, which were also demonstrated by the suppression of tube formation and migration of VEGF-treated human umbilical vein endothelial cells along with inhibition of blood vessel formation by HS-345 in a Matrigel plug assay with mice. Results of our investigation show that HS-345 inhibited the TrkA/Akt signaling pathway resulting in cell growth/angiogenesis inhibition and apoptosis induction. Based on our data, we suggest that HS-345 is a potential candidate for treating pancreatic cancer.
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Synergistic anticancer activity of HS-173, a novel PI3K inhibitor in combination with Sorafenib against pancreatic cancer cells.
Cancer Lett.
PUBLISHED: 01-06-2013
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The RAF/MEK/ERK and PI3K/AKT pathways are highly implicated in the development of pancreatic cancer. The principal objective of this study was to assess the synergic effect between Sorafenib (a RAF inhibitor) and HS-173 (a novel PI3K inhibitor) to gain insight into novel therapeutic strategies for treating pancreatic cancer. We first investigated the cytotoxic effect of co-treatment with Sorafenib and HS-173 using the Calcusyn program. Combined treatment of the two drugs synergistically inhibited the viability of Panc-1 cells (combination index<1). Concomitantly, the co-treatment induced G2/M arrest and increased apoptosis with the loss of mitochondrial membrane potential. Apoptosis resulting from the co-treatment was accompanied by increased levels of cleaved caspase-3 and PARP as well as greater numbers of TUNEL-positive apoptotic cells compared to treatment with either drug alone. Furthermore, combined treatment with these drugs decreased the expression of HIF-1? and VEGF which play an important role in angiogenesis. This anti-angiogenic effect was confirmed by the suppressed tube formation of VEGF-induced human umbilical vein endothelial cells and inhibition of blood vessel formation in a Matrigel plug assay in mice. Taken together, our study demonstrates that combined treatment with Sorafenib and HS-173 has a synergistic anti-cancer effect on pancreatic cancer cells, indicating that simultaneously targeting the RAF/MEK and PI3K/AKT pathways can induce a synergistic inhibitory effect on pancreatic cancers in which both pathways are activated. Based on the observations from our study, we suggest that the combined administration of these two drugs may be considered to be a new therapeutic regimen for treating pancreatic cancer.
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The TRPA1 agonist, methyl syringate suppresses food intake and gastric emptying.
PLoS ONE
PUBLISHED: 01-01-2013
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Transient receptor potential channel ankryn 1 (TRPA1) expressed in the gastrointestinal tract is associated with gastric motility, gastric emptying, and food intake. In this study, we investigated the effects of methyl syringate, a specific and selective TRPA1 agonist, on food intake, gastric emptying, and gut hormone levels in imprinting control region (ICR) mice. The administration of methyl syringate suppressed cumulative food intake and gastric emptying. In addition, treatment with ruthenium red (RR), a general cation channel blocker, and HC-030031, a selective TRPA1 antagonist, inhibited methyl syringate-induced reduction of food intake and delayed gastric emptying in ICR mice. Methyl syringate also increased plasma peptide YY (PYY) levels, but not glucagon-like peptide-1 (GLP-1) levels. The elevation in PYY was blocked by treatment with RR and HC-030031. The present findings indicate that methyl syringate regulates food intake and gastric emptying through a TRPA1-mediated pathway and, by extension, can contribute to weight suppression.
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Galactooligosaccharide synthesis by active ?-galactosidase inclusion bodies-containing Escherichia coli cells.
J. Microbiol. Biotechnol.
PUBLISHED: 12-01-2011
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In this study, galactooligosaccharide (GOS) was synthesized using active ?-galactosidase (beta-gal) inclusion bodies (IBs)- containing Escherichia coli (E. coli) cells. Analysis by MALDI-TOF (matrix-assisted laser desorption/ionizationtime of flight) mass spectrometry revealed that a trisaccharide was the major constituent of the synthesized GOS mixture. Additionally, the optimal pH, lactose concentration, amounts of E. coli ?-gal IBs, and temperature for GOS synthesis were 7.5, 500 g/l, 3.2 U/ml, and 37 °C, respectively. The total GOS yield from 500 g/l of lactose under these optimal conditions was about 32%, which corresponded to 160.4 g/l of GOS. Western blot analyses revealed that ?-gal IBs were gradually destroyed during the reaction. In addition, when both the reaction mixture and E. coli ?-gal hydrolysate were analyzed by high-performance thin-layer chromatography (HP-TLC), the trisaccharide was determined to be galactosyl lactose, indicating that a galactose moiety was most likely transferred to a lactose molecule during GOS synthesis. This GOS synthesis system might be useful for the synthesis of galactosylated drugs, which have recently received significant attention owing to the ability of the galactose molecules to improve the drugs solubility while decreasing their toxicity. ?-Gal IB utilization is potentially a more convenient and economic approach to enzymatic GOS synthesis, since no enzyme purification steps after the transgalactosylation reaction would be required.
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Numerical analysis of the zeta potential regarding the characteristics of a ring-type electro-osmotic mixer.
J Nanosci Nanotechnol
PUBLISHED: 11-30-2011
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The micromixer that is applied for the electro-osmotic effect in this study, which is a passive type, takes two fluids from different inlets and combines them into a single channel. The fluids then enter the mixing chamber with different inner and outer radii. Four microelectrodes are positioned on the outer wall of the mixing chamber. The electric potentials on the four microelectrodes are sinusoidal for certain values of the time, voltage, zeta potential, and frequency. In order to check the validity of the two-dimensional numerical analysis that already has been performed, we performed a three-dimensional numerical analysis using a commercial code, COMSOL. The incompressible Navier-Stokes equation is solved in this model, with a slip boundary condition on the inner and outer walls of the mixing chamber. The results of two- and three-dimensional models are graphically depicted and compared from the viewpoint of streamlines and concentration.
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Urinary bisphenol A concentrations and their implications for human exposure in several Asian countries.
Environ. Sci. Technol.
PUBLISHED: 07-20-2011
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Bisphenol A (BPA) is an industrial chemical used in the manufacture of polycarbonate plastics and epoxy resins. Due to the potential of this compound to disrupt normal endocrinal functions, concerns over human exposure to BPA have been raised. Although several studies have reported human exposure to BPA in Western nations, little is known about exposure in Asian countries. In this study, we determined total urinary BPA concentrations (free plus conjugated) in 296 urine samples (male/female: 153/143) collected from the general population in seven Asian countries, China, India, Japan, Korea, Kuwait, Malaysia, and Vietnam, using high-performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). On the basis of urinary BPA concentrations, we estimated the total daily intake. The results indicated that BPA was detected in 94.3% of the samples analyzed, at concentrations ranging from <0.1 to 30.1 ng/mL. The geometric mean concentration of BPA for the entire sample set from seven countries was 1.20 ng/mL. The highest concentration of BPA was found in samples from Kuwait (median: 3.05 ng/mL, 2.45 ?g/g creatinine), followed by Korea (2.17 ng/mL, 2.40 ?g/g), India (1.71 ng/mL, 2.09 ?g/g), Vietnam (1.18 ng/mL, 1.15 ?g/g), China (1.10 ng/mL, 1.38 ?g/g), Malaysia (1.06 ng/mL, 2.31 ?g/g), and Japan (0.95 ng/mL, 0.58 ?g/g). Among the five age groups studied (? 19, 20-29, 30-39, 40-49, and ? 50 years), the highest median concentration of BPA was found in urine samples from the age group of ? 19 years. There was no significant difference in BPA concentrations between genders (male and female) or domicile of residence (rural and urban). The estimated median daily intakes of BPA for the populations in Kuwait, Korea, India, China, Vietnam, Malaysia, and Japan were 5.19, 3.69, 2.90, 2.13, 2.01, 1.80, and 1.61 ?g/day, respectively. The estimated daily intake of BPA in the seven Asian countries was significantly lower than the tolerable daily intake recommended by the U.S. Environmental Protection Agency. This is the first study to document the occurrence of and human exposure to BPA in several Asian countries.
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Histone deacetylase inhibition improves activation of ribosomal RNA genes and embryonic nucleolar reprogramming in cloned mouse embryos.
Biol. Reprod.
PUBLISHED: 07-13-2011
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Our group found that the treatment of embryos with histone deacetylase inhibitors (HDACi), including trichostatin A, Scriptaid, suberoylanilide hydroxamic acid, and oxamflatin, after cloning by somatic cell nuclear transfer (SCNT) resulted in significantly improved efficiency. Although many researchers have investigated the use of HDACi treatment to improve the quality of cloned mouse embryos, the mechanism underlying this treatment has not been completely understood. We believe that the effect of HDACi on embryonic gene activation (EGA) is important for normal development of cloned embryos. In the present study, using highly sensitive fluorescence in situ hybridization (FISH) with probes complementary to mouse rDNA, the effect of Scriptaid on the onset of rRNA synthesis was examined in cloned embryos. In addition, to determine how Scriptaid affects pre-rRNA processing machinery in SCNT embryos with activated rDNA transcription, functional nucleolar formation was analyzed in detail by combined assessment of rRNA synthesis and nucleolar protein allocation in preimplantation embryos. In this experiment, at least part of the rRNA localization by FISH was substituted by 5-bromouridine 5-triphosphate staining after alpha-amanitin treatment. The results show that in the late 2-cell stage, a number of SCNT embryos initiated transcriptional activation while having one blastomere showing inactivated rRNA transcription and another blastomere showing activated rRNA transcription and despite both nuclei being in interphase. In addition, in some SCNT embryos, the same nuclei contained a mixture of inactively and actively transcribed rRNA, which was rarely observed in intracytoplasmic sperm injection embryos. This asynchronous transcription induced a delay of one cell cycle in SCNT embryo activation of functional nucleoli. Scriptaid can overcome this failure in the timely onset of embryonic gene transcription by activation of rRNA genes and promotion of nucleolar protein allocation during the early phase of EGA.
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Vas deferens and penis development in the imposex-exhibiting female rock shell, Thais clavigera.
Mar. Environ. Res.
PUBLISHED: 05-31-2011
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The characteristics of the development of male genitalia (penis and vas deferens) in imposex-exhibiting female rock shells, Thais clavigera, were histologically examined using specimens from a wild population and tributyltin (TBT)-exposed females in the laboratory. A variety of vas deferens morphogenesis patterns were observed in wild female T. clavigera, and the characteristics were summarized. The immature vas deferens at an initial stage, however, was only observed beneath or behind the penis, and no vas deferens was observed close to the vaginal opening (i.e., vulva) of the capsule gland in TBT-exposed females, which was different from the characteristics of vas deferens formation observed in wild females. Taking into consideration both the observed results from wild female specimens and from TBT-exposed females in the laboratory, the vas deferens sequence (VDS) index for T. clavigera was proposed as VDS 1-6.
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Specific accumulation of organotin compounds in tissues of the rock shell, Thais clavigera.
Mar. Environ. Res.
PUBLISHED: 05-30-2011
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Concentrations of organotin compounds (butyltins and phenyltins) were determined in gonad, accessory sex organs, penis, digestive gland, kidney, radula with sac, oesophagus with crop, stomach, hypobranchial gland, rectum, mantle, osphradium, ctenidium, heart, salivary gland, head ganglia and muscle of imposex-exhibiting female and male rock shells (Thais clavigera), by gas chromatography with flame photometric detection (GC-FPD). Different tissue distributions were observed between butyltin and phenyltin compounds. More than 1000 ng TBT/g wet wt. were observed in ovary, digestive gland, kidney, heart, ctenidium, osphradium, stomach, head ganglia and penis, of both imposex-exhibiting females and males. More than 1000 ng TPT/g wet wt. were found in almost all tissues of both sexes. Approximately one-third or more of total TBT was accumulated in the digestive glands of both females and males, respectively. Meanwhile, approximately 40-50% and one-half of total TPT accumulated in the digestive glands of females and males, respectively.
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Ecotoxicological evaluation of tributyltin toxicity to the equilateral venus clam, Gomphina veneriformis (Bivalvia: Veneridae).
Fish Shellfish Immunol.
PUBLISHED: 04-20-2011
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Tributyltin (TBT) is the most common pesticide in marine and freshwater environments. To evaluate the potential ecological risk posed by TBT, we measured biological responses such as growth rate, gonad index, sex ratio, the percentage of intersex gonads, filtration rate, and gill abnormalities in the equilateral venus clam (Gomphina veneriformis). Additionally, the biochemical and molecular responses were evaluated in G. veneriformis exposed to various concentrations of TBT. The growth of G. veneriformis was significantly delayed in a dose-dependent manner after exposure to all tested TBT concentrations. After TBT was administered to G. veneriformis, the gonad index decreased and the sex balance was altered. The percentage of intersex gonads also increased significantly in treated females, whereas no intersex gonads were detected in the solvent control group. Additionally, intersex gonads were detected in male G. veneriformis specimens exposed to relatively high TBT concentrations (20 ?g L?¹). The filtration rate was also reduced in a dose-dependent manner in TBT-exposed G. veneriformis. We also noted abnormal gill morphology in TBT-exposed G. veneriformis. Furthermore, increases in antioxidant enzyme activities were observed in TBT-exposed G. veneriformis clams, regardless of dosage. Vitellogenin gene expression also increased significantly in a dose-dependent manner in G. veneriformis exposed to TBT. These results provide valuable information regarding our understanding of the toxicology of TBT in G. veneriformis. Moreover, the responses of biological and molecular factors could be utilized as information for risk assessments and marine monitoring of TBT toxicity.
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Occurrence of phthalate metabolites in human urine from several Asian countries.
Environ. Sci. Technol.
PUBLISHED: 03-11-2011
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The occurrence of 14 phthalate metabolites was found in human urine samples collected from seven Asian countries: China, India, Japan, Korea, Kuwait, Malaysia, and Vietnam. Phthalate metabolites were found in all samples, indicating widespread exposure of humans to phthalates in these Asian countries. The highest total (the sum of 14 phthalates) phthalate metabolite concentrations were found in samples collected from Kuwait (median: 1050 ng/mL), followed in decreasing order by samples from India (389 ng/mL), China (234 ng/mL), Vietnam (133 ng/mL), Japan (120 ng/mL), Korea (117 ng/mL), and Malaysia (94.9 ng/mL). The creatinine-adjusted median concentrations of total phthalates for urine samples from Kuwait, India, China, Vietnam, Japan, Korea, and Malaysia were 692, 506, 289, 119, 103, 104, and 169 ?g/g creatinine, respectively. Monomethyl phthalate (mMP), monoethyl phthalate (mEP), mono (2-isobutyl phthalate) (miBP), mono-n-butyl phthalate (mBP), and metabolites of di-(2-ethylhexyl) phthalate (DEHP) were the dominant compounds, collectively accounting for >95% of the total concentrations in the samples from the seven countries. The profiles of urinary phthalate metabolite concentrations varied among the samples collected from the seven countries. Urine samples from Kuwait contained the highest concentrations of mEP (median: 391 ng/mL), mBP (94.1 ng/mL), and the metabolites of DEHP (202 ng/mL), whereas samples from China and Japan contained the highest concentrations of miBP (50.8 ng/mL) and mMP (17.5 ng/mL), respectively. mEP was the predominant metabolite in urine samples from India and Kuwait (accounting for 49% of the total), mBP and miBP were the predominant compounds in samples from China (52%), and DEHP metabolites were the predominant compounds in samples from Korea (46%) and Vietnam (52%). Based on the urinary concentrations of mEP, mBP, miBP, and DEHP metabolites of the samples from the seven Asian countries, we estimated daily intake rates of diethyl phthalate (DEP), dibutyl phthalate (DBP), and DEHP. The results indicated that people in the seven Asian countries are exposed to DEP, DBP, and DEHP at levels well below the reference doses (RfD) suggested as unsafe by the U.S. Environmental Protection Agency (EPA). The estimated exposure doses to DEHP in Kuwait, however, were above the RfD recommended by the EPA.
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Assessment of bronchodilator responsiveness following methacholine-induced bronchoconstriction in children with asthma.
Allergy Asthma Immunol Res
PUBLISHED: 01-20-2011
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The aim of this study was to investigate bronchodilator responsiveness (BDR) following methacholine-induced bronchoconstriction and to determine differences in BDR according to clinical parameters in children with asthma.
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Mitochondrial genome of Thais clavigera (Mollusca: Gastropoda): affirmation of the conserved, ancestral gene pattern within the mollusks.
Mol. Phylogenet. Evol.
PUBLISHED: 10-28-2009
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Class Gastropoda includes a large number of described species, many with extensively rearranged mitochondrial genomes. We sequenced the mitogenome of the rock shell, Thais clavigera (Gastropoda: Muricidae), an intertidal snail, using long PCR with primers designed on the basis of expressed sequence tags. The mitogenome of T. clavigera consists of 2 rRNAs, 22 tRNAs, and 13 protein-coding genes, but no control region. Structural comparisons revealed that the order Sorbeoconcha, including T. clavigera, have nearly identical mitochondrial gene patterns. However, they have an inversion between a tRNA(Phe)-tRNA(Glu) cluster that comprises 21 genes, but most of the remaining structure is similar to the putative mollusk ground pattern. These findings will provide a better insight into mitochondrial gene rearrangement over the course of gastropod evolution.
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Improved Bioethanol Production Using Activated Carbon-treated Acid Hydrolysate from Corn Hull in Pachysolen tannophilus.
Mycobiology
PUBLISHED: 03-09-2009
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To optimally convert corn hull, a byproduct from corn processing, into bioethanol using Pachysolen tannophlius, we investigated the optimal conditions for hydrolysis and removal of toxic substances in the hydrolysate via activated carbon treatment as well as the effects of this detoxification process on the kinetic parameters of bioethanol production. Maximum monosaccharide concentrations were obtained in hydrolysates in which 20 g of corn hull was hydrolyzed in 4% (v/v) H2SO4. Activated carbon treatment removed 92.3% of phenolic compounds from the hydrolysate. When untreated hydrolysate was used, the monosaccharides were not completely consumed, even at 480 h of culture. When activated carbon-treated hydrolysate was used, the monosaccharides were mostly consumed at 192 h of culture. In particular, when activated carbon-treated hydrolysate was used, bioethanol productivity (P) and specific bioethanol production rate (Qp) were 2.4 times and 3.4 times greater, respectively, compared to untreated hydrolysate. This was due to sustained bioethanol production during the period of xylose/arabinose utilization, which occurred only when activated carbon-treated hydrolysate was used.
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A comparative study of the 3D precentral gyrus model for unipolar and bipolar current stimulations.
Conf Proc IEEE Eng Med Biol Soc
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Cortical stimulation (CS) is an appealing method for treating stroke and other disorders by promoting functional recovery. It is necessary to study the effect of different cortical stimulation types through numerical simulations in order to understand the underlying mechanism. In this paper, we simulated four types of invasive CS - unipolar ECS (epidural CS), bipolar ECS, unipolar SCS (subdural CS), and bipolar SCS - to investigate and compare the effects of stimulation types. Current stimulation was considered to increase the observability of the comparison between ECS and SCS. The simulation results obtained from the 3D precentral gyrus model showed ECS and SCS had similar current density distributions with higher stimulated current. However, the differences between bipolar and unipolar stimulation are significant with higher stimulated current. As stimulated current increased, unipolar CS penetrated deeper and wider regions than bipolar CS, so it can be more effective for functional recovery.
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The computational study of subdural cortical stimulation: a quantitative analysis of voltage and current stimulation.
Conf Proc IEEE Eng Med Biol Soc
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We investigated the effect of electrode type and stimulation condition (voltage stimulation and current stimulation) in bi-polar subdural cortical stimulation (SCS). For this study, we developed a 3D realistic head model using MRI data with 1 mm(3) spatial resolution and simulated the model using the finite element method (FEM). For each study, we used three types of electrodes - disc, ring, and covered-disc - and three efficiency measures - effective depth of penetration, effective volume, and amount of CSF leakage current - to compare the effectiveness of the stimulation between two stimulation conditions. With voltage stimulation, there was no difference in effectiveness between the disc and ring electrodes. However, the amount of CSF leakage current for the covered-disc type was lower than that for the others. The effective depth of penetration and volume for the ring and disc type electrodes were higher than those for the covered-disc type. The current stimulation using the covered-disc electrode penetrated deeper than the other types of electrodes, and the CSF leakage current was still low. The result for voltage and current stimulation was quite different, as the substrate design manipulated the impedance and output current. In the current simulation, if the electrode was covered with the substrate, more current flowed to the cortex. On the other hand, with voltage stimulation, this substrate design makes the impedance between electrodes high, and the total current is reduced.
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Antitumor activity of Pulsatilla koreana extract in anaplastic thyroid cancer via apoptosis and anti-angiogenesis.
Mol Med Rep
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Plants or herb extracts have emerged as a novel approach to controling various diseases, including cancers. Among them, Pulsatilla koreana extract (PKE) has been widely used as an anti-inflammatory agent and for treating dysentery in traditional Korean and Chinese medicine. However, the effect of PKE as a cancer drug candidate has been less reported. Thus, we investigated the effect of PKE on cell growth and its mechanism in anaplastic thyroid cancer (ATC) cells. In this study, PKE suppressed the growth of ATC cells in a dose-dependent manner. Additionally, PKE induced apoptosis by increasing expression of cleaved PARP and caspase-3 in ATC cells. The apoptotic effect of PKE was confirmed by diamidino-2-phenylindole (DAPI) and terminal deoxynucleotidyltransferase-mediated nick end labeling (TUNEL) assay, showing apoptotic body and DNA fragmentation. In addition, PKE decreased the expression of hypoxia-inducible factor 1? (HIF?1?) and vascular endothelial growth factor (VEGF) as well as inhibiting tube formation and migration of human umbilical vein endothelial cells (HUVECs). Furthermore, in vivo studies showed that PKE significantly inhibited tumor growth and weight in a mouse xenograft model. Taken together, the present study demonstrated that PKE induced apoptosis, as well as inhibiting cell growth and angiogenesis in ATC cells. We suggest that PKE is a potent anticancer drug candidate for the treatment of thyroid cancer.
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SB365, Pulsatilla saponin D suppresses the proliferation of human colon cancer cells and induces apoptosis by modulating the AKT/mTOR signalling pathway.
Food Chem
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Pulsatilla koreana has been used as a traditional medicine for the treatment of several diseases. The purpose of this study was to determine if SB365, Pulsatilla saponin D isolated from the root of P. koreana inhibits the progression of colon cancer. We found that SB365 strongly suppressed the growth and proliferation of colon cancer cells and induced their apoptosis. Also, SB365 showed anti-angiogenic activity by decreasing the expression of HIF-1? and VEGF. These results were confirmed by an in vivo study showing that SB365 significantly inhibited tumor growth by the induction of apoptosis and inhibition of angiogenesis with stronger anticancer activity than 5-FU. When further examined for its anticancer mechanism, SB365 effectively suppressed the AKT/mTOR pathway both in vitro and in vivo. Taken together, our study demonstrated that SB365 inhibits the AKT/mTOR pathway, leading to the suppression of tumor growth and angiogenesis together with induction of apoptosis. Therefore, SB365 is a good candidate as a natural product for use in the treatment of colon cancer.
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Numerical study on the mixing performance of a ring-type electroosmotic micromixer with different obstacle configurations.
J Nanosci Nanotechnol
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A new type of electrokinetic micromixer with a ring-type channel is introduced for fast mixing. The proposed mixer takes two fluids from different inlets and combines them in a ring-type mixing chamber. The fluids enter two different inlets (inner radius: 25 microm and outer radius: 50 microm), respectively. The total channel length is 500 microm, and four microelectrodes are positioned on the outer wall of the mixing chamber. The electric potentials on the four microelectrodes are sinusoidal with time, having various maximum values of voltage, zeta potential and frequency. Also, in order to compare the mixing performance with different obstacle configurations, we performed a numerical analysis using a commercial code, COMSOL. The concentration of the dissolved substances in the working fluid and the flow and electric fields in the channel were investigated and the results were graphically depicted for various flow and electric conditions.
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Fabrication of high-density In(3)Sb(1)Te(2) phase change nanoarray on glass-fabric reinforced flexible substrate.
Nanotechnology
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Mushroom-shaped phase change memory (PCM) consisting of a Cr/In(3)Sb(1)Te(2) (IST)/TiN (bottom electrode) nanoarray was fabricated via block copolymer lithography and single-step dry etching with a gas mixture of Ar/Cl(2). The process was performed on a high performance transparent glass-fabric reinforced composite film (GFR Hybrimer) suitable for use as a novel substrate for flexible devices. The use of GFR Hybrimer with low thermal expansion and flat surfaces enabled successful nanoscale patterning of functional phase change materials on flexible substrates. Block copolymer lithography employing asymmetrical block copolymer blends with hexagonal cylindrical self-assembled morphologies resulted in the creation of hexagonal nanoscale PCM cell arrays with an areal density of approximately 176 Gb/in(2).
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Design, synthesis, and evaluation of 3,5-disubstituted 7-azaindoles as Trk inhibitors with anticancer and antiangiogenic activities.
J. Med. Chem.
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Tropomyosin-related kinase A (TrkA) is considered a promising target in the development of a therapeutic treatment of cancer and pain. In this study, we designed and synthesized a series of novel 7-azaindole-based Trk kinase inhibitors through the structure-based design strategy. By varying the functional groups at the 3 and 5 positions of a 7-azaindole scaffold, we studied the structure-activity relationships (SAR) profiles and identified a series of potent Trk inhibitors. Representative derivatives showed desirable activity in cellular proliferation and apoptosis assays. Moreover, these inhibitors exhibited noteworthy antiangiogenic activity.
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Effect of a hot water extract of Chlorella vulgaris on proliferation of IEC-6 cells.
Int. J. Mol. Med.
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Chlorella vulgaris, a unicellular microalgae, exerts various biological effects; however their effect on proliferation signaling pathways in normal cells has not been studied. We investigated the effect of hot water extracts of Chlorella vulgaris (CVE) on cell proliferation and related signaling pathways in rat intestinal epithelial cells (IEC-6). CVE increased the expression of insulin-like growth factor-I receptor (IGF-IR) and the phosphorylation of focal adhesion kinase (FAK) and Src. In addition, CVE induced activation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt pathways. We verified the increased phosphorylation of extracellular-signal-related kinase (ERK) and Akt and the increased expression of the PI3K regulatory subunit p85. CVE also influenced the canonical Wnt pathway through increased expression of the nuclear ?-catenin, cyclin D1. Tyr-397 of FAK mediates interactions with Src homology 2 (SH2) domains in a number of other signaling proteins, including PI3K, PLC-?, Shc, Grb7, Src and Nck2. Because CVE induced FAK activation, FAK may affect the Wnt pathway. Addition of a FAK inhibitor decreased the expression of nuclear ?-catenin, cyclin D1 and c-myc, and increased the expression of cytosolic ?-catenin. We conclude that CVE stimulated proliferation of IEC-6 cells via the MAPK, PI3K/Akt and canonical Wnt pathways, and that this affected the canonical Wnt pathway.
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Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method.
Nanoscale Res Lett
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In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2.
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