In JoVE (1)

Other Publications (53)

Articles by Yizhong Huang in JoVE

Other articles by Yizhong Huang on PubMed

Exposure to Metal Mixtures and Human Health Impacts in a Contaminated Area in Nanning, China

Environment International. Aug, 2005  |  Pubmed ID: 15979144

Cadmium and lead have been identified as very toxic metals, which are widely present in the environment due to natural and anthropogenic emissions. Many studies have shown that the food chain is the main pathway of cadmium and lead transfer from the environment to humans. It is well documented that many factors will affect their transfer through food chains. Previous investigations on heavy metals were mostly concentrated on one contaminant in isolation. However, in real environments, exposure to mixtures of metals is ubiquitous such that cadmium pollution is invariably being associated with lead and zinc, etc. This study focuses on the contamination and health effects of the metal mixtures. For this purpose, a dietary survey was taken for 3 groups in Nanning in October 2002. Samples of soils, plants (vegetables), urine and blood of humans were measured for Cd, Fe, Cu, Zn, Ca and Pb, in addition, the urinary indicators of renal dysfunction Albumin (ALB), N-acetyl-beta-D-glucosaminidase (NAG), Beta-2-microglobulin (beta2-MG) and Retinol-binding protein (RBP) in urine were also measured. Results showed that soil contamination with metal mixtures had caused significant renal dysfunction of the local residents living in the contaminated area, and the dose-response curve was somewhat altered by the mixed contamination of Cd and Pb as well as the intake of other minerals. The importance of mixtures of metal contamination and human health are also discussed in this paper.

In Vitro Biodegradation of Three Brushite Calcium Phosphate Cements by a Macrophage Cell-line

Biomaterials. Sep, 2006  |  Pubmed ID: 16720039

Depending upon local conditions, brushite (CaHPO4 x 2 H2O) cements may be largely resorbed or (following hydrolysis to hydroxyapatite) remain stable in vivo. To determine which factors influence cement resorption, previous studies have investigated the solution-driven degradation of brushite cements in vitro in the absence of any cells. However, the mechanism of cell-mediated biodegradation of the brushite cement is still unknown. The aim of the current study was to observe the cell-mediated biodegradation of brushite cement formulations in vitro. The cements were aged in the presence of a murine cell line (RAW264.7), which had the potential to form osteoclasts in the presence of the receptor for nuclear factor kappa B ligand (RANKL) in vitro, independently of macrophage colony stimulating factor (M-CSF). The cytotoxicity of the cements on RAW264.7 cells and the calcium and phosphate released from materials to the culture media were analysed. Scanning electron microscopy (SEM) and focused ion beam (FIB) microscopy were used to characterise the ultrastructure of the cells. The results showed that the RAW264.7 cell line formed multinucleated TRAP positive osteoclast-like cells, capable of ruffled border formation and lacunar resorption on the brushite calcium phosphate cement in vitro. In the osteoclast-like cell cultures, ultrastructural analysis by SEM revealed phenotypic characteristics of osteoclasts including formation of a sealing zone and ruffled border. Penetration of the surface of the cement, was demonstrated using FIB, and this showed the potential demineralising effect of the cells on the cements. This study has set up a useful model to investigate the cell-mediated cement degradation in vitro.

Macrophage-mediated Biodegradation of Poly(DL-lactide-co-glycolide) in Vitro

Journal of Biomedical Materials Research. Part A. Dec, 2006  |  Pubmed ID: 16817218

Biodegradation of poly-DL-lactide-co-glycolide (PLGA) both in vitro and in vivo has been well documented. However, the roles that macrophages and their fused multinucleated giant cells (MNGCs) play in this biodegradation are still unclear. The current study aimed to investigate macrophage-mediated biodegradation of PLGA thin films and of PLGA composites with hydroxyapatite (HA) and tricalcium phosphate (TCP) ceramic powders in vitro using a murine macrophage cell line (RAW 264.7). The interactions were analyzed by using cell viability assays, scanning electron microscopy, and focused ion beam microscopy. The results showed that RAW 264.7 cells effectively attached and proliferated on the PLGA films and PLGA-HA, PLGA-TCP composites. The RAW 264.7 cells were observed to aggregate and fuse to form MNGCs. The cell processes on the membrane, or pseudopodia, penetrated into the PLGA films and evidently eroded the surface. We conclude that macrophages and fused MNGCs actively respond to PLGA films as substratum and degrade the surface of this polymer.

Cross-sectional Observation of Yttrium and Nickel Oxide Doped Ceria Powder

Journal of Nanoscience and Nanotechnology. Jun, 2009  |  Pubmed ID: 19504938

In this paper, microstructures of ceria powder, synthesized using spray pyrolysis method, were characterized by focused ion beam technique and transmission electron microscopy. Dependence of the shape of powder particle on the size was found. It appears a spherical shape with the diameter less than approximately 500 nm and shows cup-like shape when their diameters become larger as a result of concaving. This suggests that the spherical particle has a hollow structure as proved by focused ion beam cross-sectioning. It was also found that both the inner and the outer shells of particles are crystalline but comprised of different phases with the inner shell being NiO and the outer shell CeO2. These results benefit from a transmission electron microscopy sample preparation method to produce a cross-section of the particle. The detail of the method was described in the paper.

Study of Nano-Ag Particles Doped TiO2 Prepared by Photocatalysis

Journal of Nanoscience and Nanotechnology. Jun, 2009  |  Pubmed ID: 19504939

Nano-silver (Ag) particle doped TiO2 composite photocatalyst was prepared by photocatalytic reaction of anatase TiO2 with AgNO3 solution. Microstructures of these particles were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDAX) and transmission electron microscopy (TEM). Its photocatalytic behavior was examined by the degradations of two dyes, methyl orange and methylene blue. In contrast to Ag free TiO2 particles, the nano-Ag particle doped TiO2 photocatalyst exhibits much higher catalytic activity. It was also found that 1.0 wt% Ag doped to the TiO2 particles, synthesized through 10 hour ultraviolet (UV) irradiation, offer the best photocatalytic property.

Facile "needle-scratching" Method for Fast Catalyst Patterns Used for Large-scale Growth of Densely Aligned Single-walled Carbon-nanotube Arrays

Small (Weinheim an Der Bergstrasse, Germany). Sep, 2009  |  Pubmed ID: 19517484

Solution-processable Semiconducting Thin-film Transistors Using Single-walled Carbon Nanotubes Chemically Modified by Organic Radical Initiators

Chemical Communications (Cambridge, England). Dec, 2009  |  Pubmed ID: 19921023

The reactivity of organic radicals produced by 1,1'-azobis(cyanocyclohexane) (ACN) is tuned to selectively suppress electrical conduction of small diameter single-walled carbon nanotubes, and the modified tubes are able to produce high-mobility (approximately 10 cm2 V(-1) s(-1)) and solution-processable thin-film transistors with full semiconductor device yield, promising applications in high-performance printable electronics.

Facile "scratching" Method with Common Metal Objects to Generate Large-scale Catalyst Patterns Used for Growth of Single-walled Carbon Nanotubes

ACS Applied Materials & Interfaces. Sep, 2009  |  Pubmed ID: 20355809

A facile "scratching" method to pattern a catalyst with commonly used metal objects, such as blade, pen cover, tweezers, watchband, knife, key, clamp, and coin, was developed. The single-walled carbon nanotube (SWCNT) networks and well-aligned SWCNT arrays successfully grew by chemical vapor deposition on the scratched catalyst patterns on Si/SiO(x) and quartz, respectively. This method provides an extremely simple and nearly zero-cost way to fabricate large-scale catalyst patterns used for controlled growth of SWCNT arrays, which could have potential applications in the fabrication of CNT-based devices.

Polysomatic Apatites

Acta Crystallographica. Section B, Structural Science. Feb, 2010  |  Pubmed ID: 20101078

Certain complex structures are logically regarded as intergrowths of chemically or topologically discrete modules. When the proportions of these components vary systematically a polysomatic series is created, whose construction provides a basis for understanding defects, symmetry alternation and trends in physical properties. Here, we describe the polysomatic family A(5N)B(3N)O(9N + 6)X(Ndelta) (2 < or = N < or = infinity) that is built by condensing N apatite modules (A(5)B(3)O(18)X(delta)) in configurations to create B(n)O(3n + 1) (1 < or = n < or = infinity) tetrahedral chains. Hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] typifies a widely studied polysome where N = 2 and the tetrahedra are isolated in A(10)(BO(4))(6)X(2) compounds, but N = 3 A(15)(B(2)O(7))(3)(BO(4))(3)X(3) (ganomalite) and N = 4 A(20)(B(2)O(7))(6)X(4) (nasonite) are also known, with the X site untenanted or partially occupied as required for charge balance. The apatite modules, while topologically identical, are often compositionally or symmetrically distinct, and an infinite number of polysomes is feasible, generally with the restriction being that an A:B = 5:3 cation ratio be maintained. The end-members are the N = 2 polysome with all tetrahedra separated, and N = infinity, in which the hypothetical compound A(5)B(3)O(9)X contains infinite, corner-connected tetrahedral strings. The principal characteristics of a polysome are summarized using the nomenclature apatite-(A B X)-NS, where A/B/X are the most abundant species in these sites, N is the number of modules in the crystallographic repeat, and S is the symmetry symbol (usually H, T, M or A). This article examines the state-of-the-art in polysomatic apatite synthesis and crystallochemical design. It also presents X-ray and neutron powder diffraction investigations for several polysome chemical series and examines the prevalence of stacking disorder by electron microscopy. These insights into the structure-building principles of apatite polysomes will guide their development as functional materials.

Percutaneous Radiofrequency Thermocoagulation for the Treatment of Different Types of Trigeminal Neuralgia: Evaluation of Quality of Life and Outcomes

Journal of Huazhong University of Science and Technology. Medical Sciences = Hua Zhong Ke Ji Da Xue Xue Bao. Yi Xue Ying De Wen Ban = Huazhong Keji Daxue Xuebao. Yixue Yingdewen Ban. Jun, 2010  |  Pubmed ID: 20556590

Radiofrequency thermocoagulation (RFT) of the gasserian ganglion is a routine and effective technique for the treatment of classical trigeminal neuralgia (CTN). In this study we compared its efficacy in patients with CTN and atypically symptomatic or mixed trigeminal neuralgia (MTN). Fifty-seven patients were treated with RFT for trigeminal neuralgia from June 2006 to February 2009. Thirty patients had CTN, and 27 had MTN. Outcomes were measured by using the visual analog pain scale (VAS) and patients' reports of quality of life (QOL), medication usage, and complications over a follow-up period of up to 3 years. Our results showed that the patients with MTN were younger, tended to have bilaterial involvement of the first division, and were unresponsive to treatment. All surgeries were completed smoothly. About 86.7% CTN patients and 48.1% MTN patients responded immediately to RFT. The VAS scores were significantly higher in the CTN group than in MTN group (P<0.05). Kaplan-Meier curves showed that 1-year, 2-year, and 3-year pain relief rates were 76.7%, 73.3%, and 73.3% in the CTN group and 46.6%, 41.4%, and 41.4% in the MTN group, respectively. The rates of pain relief for both groups leveled off at 2 years. Complications included numbness, dysesthesia, and anesthesia dolorosa. RFT did not cause any deaths and complications were low. The treatment was very effective for CTN and, to some degrees, effective for MTN. If numbness, dysesthesia, and anesthesia dolorosa are limited to the trigger area, QOL will be greatly improved.

Highly Efficient Restoration of Graphitic Structure in Graphene Oxide Using Alcohol Vapors

ACS Nano. Sep, 2010  |  Pubmed ID: 20718442

Solution-based processes involving the chemical oxidation of graphite and reduction of the obtained graphene oxide (GO) sheets have attracted much attention for preparing graphene films for printed electronics and biosensors. However, the low electrical conductivity of reduced GO is still hindering the development of electronic applications. This article presents that GO sheets reduced by high-temperature alcohol vapors exhibit highly graphitic structures and excellent electrical conductivity. The sheet resistance of thin transparent films is lowered to ∼15 kΩ/◻ (>96% transparency). Field-effect transistors produced from these reduced GO sheets exhibit high effective field-effect hole mobility up to 210 cm(2)/V x s. Raman spectroscopic studies reveal that the conductivity enhancement in the low mobility regime is attributed to the removal of chemical functional groups and the formation of six-fold rings. In the high mobility regime, the growth of the graphitic domain size becomes dominant for enhancing its electrical conductivity. The excellent electrical conductivity of the reduced GO sheets promises potential electronic applications.

Photochemically Controlled Synthesis of Anisotropic Au Nanostructures: Platelet-like Au Nanorods and Six-star Au Nanoparticles

ACS Nano. Oct, 2010  |  Pubmed ID: 20973574

We report the shape-controlled synthesis of anisotropic Au nanostructures through TiO(2)-assisted photochemical reduction of HAuCl(4). By using this method, we have successfully synthesized the platelet-like Au nanorods and six-star Au nanoparticles. Importantly, the platelet Au nanorod exhibits the unique asymmetric five-twinned structure. The colloidal TiO(2) sols were used as both the photocatalyst to initiate the reaction and the stabilizing agent for the produced Au nanostructures. Significantly, in this photochemical process, the tunable irradiation intensity allows us to kinetically control the crystal evolution at various growth stages, leading to the shape difference of ultimate gold nanostructures. Our synthetic method shows a great potential as an alternative or supplement to the other wet chemical approaches for the shape-control of metallic nanostructures.

Dual-phase Titanate/anatase with Nitrogen Doping for Enhanced Degradation of Organic Dye Under Visible Light

Chemistry (Weinheim an Der Bergstrasse, Germany). Feb, 2011  |  Pubmed ID: 21284045

Chemical Reaction Between Ag Nanoparticles and TCNQ Microparticles in Aqueous Solution

Small (Weinheim an Der Bergstrasse, Germany). May, 2011  |  Pubmed ID: 21495182

The chemical reaction between Ag nanoparticles (Ag NPs) and 7,7',8,8'- tetracycanoquinodimethane (TCNQ) microparticles (MPs) in aqueous solution for the formation of Ag-NP-decorated Ag-TCNQ nanowires is reported. Based on the results obtained by UV-vis spectroscopy and scanning electron microscopy (SEM), it is proposed that the reaction between Ag NPs and TCNQ MPs includes three stages, namely, aggregation of NPs and MPs, diffusion and reaction between NPs and MPs, and formation of Ag-TCNQ nanowires. The as-synthesized semiconducting Ag-TCNQ nanowires show good performance in nonvolatile memory devices with multiple write-read-erase-read (WRER) cycles in air.

Synthesis of Hexagonal Close-packed Gold Nanostructures

Nature Communications. 2011  |  Pubmed ID: 21522136

Solid gold is usually most stable as a face-centred cubic (fcc) structure. To date, no one has synthesized a colloidal form of Au that is exclusively hexagonal close-packed (hcp) and stable under ambient conditions. Here we report the first in situ synthesis of dispersible hcp Au square sheets on graphene oxide sheets, which exhibit an edge length of 200-500 nm and a thickness of ~ 2.4 nm (~ 16 Au atomic layers). Interestingly, the Au square sheet transforms from hcp to a fcc structure on exposure to an electron beam during transmission electron microscopy analysis. In addition, as the square sheet grows thicker (from ~ 2.4 to 6 nm), fcc segments begin to appear. A detailed experimental analysis of these structures shows that for structures with ultrasmall dimensions (for example, <~ 6 nm thickness for the square sheets), the previously unobserved pure hcp structure becomes stable and isolable.

Expression, Purification of Herpes Simplex Virus Type 1 US11 Protein, and Production of US11 Polyclonal Antibody

Virology Journal. Oct, 2011  |  Pubmed ID: 22044769

The US11 protein of herpes simplex virus type 1 (HSV-1) is a small, highly basic phosphoprotein expressed at late times during infection. To date, the function of US11 protein in cell culture and animal models is poorly understood. To further investigate the function of the US11 protein, this study was undertaken to express the US11 protein and raise a polyclonal antibody.

Graphene Oxide-templated Synthesis of Ultrathin or Tadpole-shaped Au Nanowires with Alternating Hcp and Fcc Domains

Advanced Materials (Deerfield Beach, Fla.). Feb, 2012  |  Pubmed ID: 22252895

Ultrathin Au nanowires (AuNWs) and tadpole-shaped nanowires are synthesized on graphene oxide (GO) sheet templates. For the first time, 1.6 nm-diameter AuNWs are shown to contain hexagonal close-packed (hcp) crystal domains, and the tadpole-shaped nanowires exhibit alternating sets of hcp and face-centered cubic (fcc) structures, associated with variation in wire thickness.

One-step Solvothermal Synthesis of Single-crystalline TiOF2 Nanotubes with High Lithium-ion Battery Performance

Chemistry (Weinheim an Der Bergstrasse, Germany). Mar, 2012  |  Pubmed ID: 22362627

Single-crystalline TiOF(2) nanotubes were prepared by a one-step solvothermal method. The nanotubes are rectangular in shape with a length of 2-3 μm, width of 200-300 nm, and wall thickness of 40-60 nm. The formation of TiOF(2) nanotubes is directly driven by the interaction between TiF(4) and oleic acid in octadecane to form the 1D nanorods, and this is followed by a mass diffusion process to form the hollow structures. The synthesis approach can be extended to grow TiOF(2) nanoparticles and nanorods. Compared with TiO(2), which is the more commonly considered anode material in lithium-ion batteries, TiOF(2) has the advantages of a lower Li-intercalation voltage (e.g., to help increase the total voltage of the battery cell) and higher specific capacities. The TiOF(2) nanotubes showed good Li-storage properties with high specific capacities, stable cyclabilities, and good rate capabilities.

Self-organization of a Hybrid Nanostructure Consisting of a Nanoneedle and Nanodot

Small (Weinheim an Der Bergstrasse, Germany). Sep, 2012  |  Pubmed ID: 22730203

A special materials system that allows the self-organization of a unique hybrid nanonipple structure is developed. The system consists of a nanoneedle with a small nanodot sitting on top. Such hybrid nanonipples provide building blocks to assemble functional devices with significantly improved performance. The application of the system to high-sensitivity gas sensors is also demonstrated.

Full Solution-processed Synthesis of All Metal Oxide-based Tree-like Heterostructures on Fluorine-doped Tin Oxide for Water Splitting

Advanced Materials (Deerfield Beach, Fla.). Oct, 2012  |  Pubmed ID: 22859386

Well-ordered tree-like functional heterostructures, composed of the environmentally friendly oxides ZnO, TiO(2) , and CuO, on a fluorine-doped tin oxide substrate are realized by a practical, cost-effective, solution-processable strategy. The heterostructures are demonstrated to be an efficient light-harvesting medium in a photo-electrochemical cell to split water for hydrogen-gas generation, and the developed strategy provides a highly promising, cheap, green way to fabricate multifunctional hierarchically branched structures for many potential applications.

Photoinduced Superhydrophilicity of TiO2 Thin Film with Hierarchical Cu Doping

Science and Technology of Advanced Materials. Apr, 2012  |  Pubmed ID: 27877479

Hydrophilic Cu-TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants.

Controlled Synthesis of Double-wall A-FePO4 Nanotubes and Their LIB Cathode Properties

Small (Weinheim an Der Bergstrasse, Germany). Apr, 2013  |  Pubmed ID: 23239602

Double-wall amorphous FePO4 nanotubes are prepared by an oil-phase chemical route. The inward diffusion of vacancies and outward diffusion of ions through passivation layers result in double-wall nanotubes with thin walls. Such a process can be extended to prepare hollow polydedral nanocrystals and hollow ellipsoids. The double-wall FePO4 nanotubes show interesting cathode performance in Li ion batteries.

Synthesis of Porous Amorphous FePO4 Nanotubes and Their Lithium Storage Properties

Chemistry (Weinheim an Der Bergstrasse, Germany). Jan, 2013  |  Pubmed ID: 23281066

Numerical Modeling of Mid-infrared Fiber Optical Parametric Oscillator Based on the Degenerated FWM of Tellurite Photonic Crystal Fiber

Applied Optics. Jan, 2013  |  Pubmed ID: 23338203

Mid-infrared fiber optical parametric oscillators (MIR FOPOs) based on the degenerate four-wave mixing (DFWM) of tellurite photonic crystal fibers (PCFs) are proposed and modeled for the first time. Using the DFWM coupled-wave equations, numerical simulations are performed to analyze the effects of tellurite PCFs, single-resonant cavity, and pump source on the MIR FOPO performances. The numerical results show that: (1) although a longer tellurite PCF can decrease the pump threshold of MIR FOPOs to a few watts only, the high conversion-efficiency of MIR idler usually requires a short-length optimum PCF with low loss; (2) compared with the single-pass DFWM configurations of the MIR fiber sources published previously, the stable oscillation of signal light in single-resonant cavity can significantly promote the MIR idler output efficiency. With a suggested tellurite PCF as parametric gain medium, the theoretical prediction indicates that such a MIR FOPO could obtain a wide MIR-tunable range and a high conversion efficiency of more than 10%.

A Hybrid Nanostructure Array for Gas Sensing with Ultralow Field Ionization Voltage

Nanotechnology. May, 2013  |  Pubmed ID: 23548746

We fabricate a unique hybrid nanostructure array for gas sensing based on the polarization mechanism at the nanoscale. It is shown that with platinum nanocrystallites on the top of each nanoneedle, this array can work at ultralow voltages (less than 10 V) as a field ionization gas sensor. We believe that the polarized platinum brings about a local enhanced electrical field, leading to the direct field ionization of gas molecules, which is confirmed by calculations of the charge accumulation and electrical field distribution.

1.06 μm Q-switched Ytterbium-doped Fiber Laser Using Few-layer Topological Insulator Bi₂Se₃ As a Saturable Absorber

Optics Express. Dec, 2013  |  Pubmed ID: 24514504

Passive Q-switching of an ytterbium-doped fiber (YDF) laser with few-layer topological insulator (TI) is, to the best of our knowledge, experimentally demonstrated for the first time. The few-layer TI: Bi₂Se₃ (2-4 layer thickness) is firstly fabricated by the liquid-phase exfoliation method, and has a low saturable optical intensity of 53 MW/cm² measured by the Z-scan technique. The optical deposition technique is used to induce the few-layer TI in the solution onto a fiber ferrule for successfully constructing the fiber-integrated TI-based saturable absorber (SA). By inserting this SA into the YDF laser cavity, stable Q-switching operation at 1.06 μm is achieved. The Q-switched pulses have the shortest pulse duration of 1.95 μs, the maximum pulse energy of 17.9 nJ and a tunable pulse-repetition-rate from 8.3 to 29.1 kHz. Our results indicate that the TI as a SA is also available at 1 μm waveband, revealing its potential as another broadband SA (like graphene).

Towards Perfectly Ordered Novel ZnO/Si Nano-heterojunction Arrays

Small (Weinheim an Der Bergstrasse, Germany). Jan, 2014  |  Pubmed ID: 23881853

The fabrication of a highly ordered novel ZnO/Si nano-heterojuntion array is introduced. ZnO seed layer is first deposited on the Si (P<111>) surface. The nucleation sites are then defined by patterning the surface through focused ion beam (FIB) system. The ZnO nanorods are grown on the nucleation sites through hydrothermal process. The whole fabrication process is simple, facile and offers direct control of the space, length and aspect ratio of the array. It is found that ZnO/Si nanojunctions show an improved interface when subjected to heat treatment. The recrystallization of ZnO and the tensile lattice strain of Si developed during the heating process contribute the enhancement of their photoresponses to white light. The photoluminescence (PL) measurement result of nano-heterojunction arrays with different parameters is discussed.

Nuclear Localization Signals of Varicella Zoster Virus ORF4

Virus Genes. Apr, 2014  |  Pubmed ID: 24398930

The varicella zoster virus (VZV) ORF4 protein, one of immediate-early genes protein, is associated with the tegument in purified virions. ORF4 protein functions at both transcriptional and post-transcriptional levels, present during different phase of whole VZV life cycle. ORF4 protein acts as a nucleocytoplasm shuttle protein, the precise nuclear location signals (NLS) and molecular mechanisms of nucleocytoplasm transport are not elucidated. At this study, we constructed a series of mutants, used fluorescence microscopy and Co-IP analysis to identify an unconventional bipartite NLS ((130)RKHRDRSLSNRRRRP(144)) in VZV ORF4. This study also demonstrates that nuclear import of VZV ORF4 occurs via a Ran-dependent pathway with importin-α5 and importin-β1. Additionally, NLS function of ORF4 is independent from VZV ORF62 protein. ORF62 protein cannot influence the intracellular distribution of ORF4 protein without NLS. So interaction between ORF4 and ORF62 protein is speculated to occur in nucleus. Thus, NLS is indispensable for the post-transcriptional function of ORF4.

The Role of Metal Layers in the Formation of Metal-silicon Hybrid Nanoneedle Arrays

Nanoscale. Mar, 2014  |  Pubmed ID: 24531185

We investigated nanoneedle arrays fabricated on a series of metal-silicon substrates using Ga(+) ion beam patterning. It is shown that the low sputtering rate of the metal is preserved on the tip of each nanoneedle in the form of a gallium alloy nanodot. The generated nanodot was found to greatly alleviate the ion sputtering of the underlying materials. These protective metals are promising materials that act as a shelter for the functional layer, which is vulnerable to ion beam irradiation. In the present work, as an example, we report a bundle of GaAs nanowhiskers that were successfully grown on each gold nanodot protected by an iron-gallium alloy.

Zeolitic Imidazolate Framework 67-derived High Symmetric Porous Co₃O₄ Hollow Dodecahedra with Highly Enhanced Lithium Storage Capability

Small (Weinheim an Der Bergstrasse, Germany). May, 2014  |  Pubmed ID: 24616440

Self-mode-locked 2 μm Tm(3+)-doped Double-clad Fiber Laser with a Simple Linear Cavity

Applied Optics. Feb, 2014  |  Pubmed ID: 24663268

We demonstrate the self-mode-locking operation of a thulium (Tm)-doped fiber laser (TDFL) with a simple linear cavity. Since the laser cavity does not include any specific mode-locker, we experimentally investigate and analyze the self-mode-locking mechanism. The mode-locking operation is attributed to the combination of the self-phase modulation effect and the weak saturable absorption of the high-concentration Tm-doped fiber. The mode-locked TDFL operates at a central wavelength of 1985.5 nm with the 3 dB spectral linewidth of 0.18 nm. The self-mode-locking generates a large pulse energy of 32.7 nJ with a pulsed repetition rate of 2.05 MHz and is stable with a radio-frequency signal-to-noise ratio of more than 54 dB. To the best of our knowledge, it is the first demonstration of a 2 μm Tm-doped fiber laser mode-locked by such technique.

GaAs/AlGaAs Nanowire Photodetector

Nano Letters. May, 2014  |  Pubmed ID: 24678794

We demonstrate an efficient core-shell GaAs/AlGaAs nanowire photodetector operating at room temperature. The design of this nanoscale detector is based on a type-I heterostructure combined with a metal-semiconductor-metal (MSM) radial architecture, in which built-in electric fields at the semiconductor heterointerface and at the metal/semiconductor Schottky contact promote photogenerated charge separation, enhancing photosensitivity. The spectral photoconductive response shows that the nanowire supports resonant optical modes in the near-infrared region, which lead to large photocurrent density in agreement with the predictions of electromagnetic and transport computational models. The single nanowire photodetector shows a remarkable peak photoresponsivity of 0.57 A/W, comparable to large-area planar GaAs photodetectors on the market, and a high detectivity of 7.2 × 10(10) cm·Hz(1/2)/W at λ = 855 nm. This is promising for the design of a new generation of highly sensitive single nanowire photodetectors by controlling the optical mode confinement, bandgap, density of states, and electrode engineering.

Preparation of Few-layer Bismuth Selenide by Liquid-phase-exfoliation and Its Optical Absorption Properties

Scientific Reports. Apr, 2014  |  Pubmed ID: 24762534

Bismuth selenide (Bi2Se3), a new topological insulator, has attracted much attention in recent years owing to its relatively simple band structure and large bulk band gap. Compared to bulk, few-layer Bi2Se3 is recently considered as a highly promising material. Here, we use a liquid-phase exfoliation method to prepare few-layer Bi2Se3 in N-methyl-2-pyrrolidone or chitosan acetic solution. The resulted few-layer Bi2Se3 dispersion demonstrates an interesting absorption in the visible light region, which is different from bulk Bi2Se3 without any absorption in this region. The absorption spectrum of few-layer Bi2Se3 depends on its size and layer number. At the same time, the nonlinear and saturable absorption of few-layer Bi2Se3 thin film in near infrared is also characterized well and further exploited to generate laser pulses by a passive Q-switching technique. Stable Q-switched operation is achieved with a lower pump threshold of 9.3 mW at 974 nm, pulse energy of 39.8 nJ and a wide range of pulse-repetition-rate from 6.2 to 40.1 kHz. Therefore, the few-layer Bi2Se3 may excite a potential applications in laser photonics and optoelectronic devices.

Transition-metal-ion-mediated Polymerization of Dopamine: Mussel-inspired Approach for the Facile Synthesis of Robust Transition-metal Nanoparticle-graphene Hybrids

Chemistry (Weinheim an Der Bergstrasse, Germany). Jun, 2014  |  Pubmed ID: 24862644

Inspired by the high transition-metal-ion content in mussel glues, and the cross-linking and mechanical reinforcement effects of some transition-metal ions in mussel threads, high concentrations of nickel(II), cobalt(II), and manganese(II) ions have been purposely introduced into the reaction system for dopamine polymerization. Kinetics studies were conducted for the Ni(2+)-dopamine system to investigate the polymerization mechanism. The results show that the Ni(2+) ions could accelerate the assembly of dopamine oligomers in the polymerization process. Spectroscopic and electron microscopic studies reveal that the Ni(2+) ions are chelated with polydopamine (PDA) units, forming homogeneous Ni(2+)-PDA complexes. This facile one-pot approach is utilized to construct transition-metal-ion-PDA complex thin coatings on graphene oxide, which can be carbonized to produce robust hybrid nanosheets with well-dispersed metallic nickel/metallic cobalt/manganese(II) oxide nanoparticles embedded in PDA-derived thin graphitic carbon layers. The nickel-graphene hybrid prepared by using this approach shows good catalytic properties and recyclability for the reduction of p-nitrophenol.

Cadmium Sulfide Quantum Dots Supported on Gallium and Indium Oxide for Visible-light-driven Hydrogen Evolution from Water

ChemSusChem. Sep, 2014  |  Pubmed ID: 25045039

In this work, CdS quantum dots (QDs) supported on Ga2O3 and In2O3 are applied for visible-light-driven H2 evolution from aqueous solutions that contain lactic acid. With Pt as the cocatalyst, the H2 evolution rates on CdS/Pt/Ga2O3 and CdS/Pt/In2O3 are as high as 995.8 and 1032.2 μmol h(-1), respectively, under visible light (λ>420 nm) with apparent quantum efficiencies of 43.6 and 45.3% obtained at 460 nm, respectively. These are much higher than those on Pt/CdS (108.09 μmol h(-1)), Pt/Ga2O3 (0.12 μmol h(-1)), and Pt/In2O3 (0.05 μmol h(-1)). The photocatalysts have been characterized thoroughly and their band structures and photocurrent responses have been measured. The band alignment between the CdS QDs and In2O3 can lead to interfacial charge separation, which cannot occur between the CdS QDs and Ga2O3. Among the various possible factors that contribute to the high H2 evolution rates on CdS/Pt/oxide, the surface properties of the metal oxides play important roles, which include (i) the anchoring of CdS QDs and Pt nanoparticles for favorable interactions and (ii) the efficient trapping of photogenerated electrons from the CdS QDs because of surface defects (such as oxygen defects) based on photoluminescence and photocurrent studies.

Hierarchically Porous Three-dimensional Electrodes of CoMoO₄ and ZnCo₂O₄ and Their High Anode Performance for Lithium Ion Batteries

Nanoscale. Sep, 2014  |  Pubmed ID: 25117647

Ternary metal oxides have been receiving wide attention in electrochemical energy storage due to their rich redox reactions and tuneable conductivity. We present a simple solution-based method to prepare a 3D interconnected porous network of ternary metal oxide (CoMoO₄ and ZnCo₂O₄) nanostructures on macroporous nickel foam. The open-structured networks with different degrees of porosity endow them with high surface areas of electro-active sites. The Li ion storage properties of both anodes are investigated. High rate capability and long term cycling stability are achieved for both systems.

Widely-tunable, Passively Q-switched Erbium-doped Fiber Laser with Few-layer MoS2 Saturable Absorber

Optics Express. Oct, 2014  |  Pubmed ID: 25401559

We propose and demonstrate a MoS2-based passively Q-switched Er-doped fiber laser with a wide tuning range of 1519.6-1567.7 nm. The few-layer MoS2 nano-platelets are prepared by the liquid-phase exfoliation method, and are then made into polymer-composite film to construct the fiber-compatible MoS2 saturable absorber (SA). It is measured at 1560 nm wavelength, that such MoS2 SA has the modulation depth of ∼ 2% and the saturable optical intensity of ∼ 10 MW/cm(2). By further inserting the filmy MoS2-SA into an Er-doped fiber laser, stable Q-switching operation with a 48.1 nm continuous tuning from S- to C-waveband is successfully achieved. The shortest pulse duration and the maximum pulse energy are 3.3 μs and 160 nJ, respectively. The repetition rate and the pulse duration under different operation conditions have been also characterized. To the best of our knowledge, it is the first demonstration of MoS2 Q-switched, widely-tunable fiber laser.

Passively Q-switched Nd:YAlO₃nanosecond Laser Using MoS₂as Saturable Absorber

Optics Express. Nov, 2014  |  Pubmed ID: 25402132

We report on the first passively Q-switched Nd:YAlO₃ laser at ~1079.5 nm using MoS₂ as saturable absorber. The MoS₂ saturable absorber is fabricated by transferring the liquid-phase-exfoliated MoS₂ nanosheets onto a BK7 glass substrate. By inserting the glass MoS₂ saturable absorber into a plano-concave Nd:YAlO₃ laser cavity, we obtain a stable Q-switched laser operation with a maximum average output power of 0.26 W corresponding to a pulse repetition rate of 232.5 kHz, a pulse width of 227 ns and a pulse energy of about 1.11 μJ. The results experimentally confirm the promising application of the new kind of 2D material, few-layer MoS₂, in solid state lasers.

A Flexible Alkaline Rechargeable Ni/Fe Battery Based on Graphene Foam/carbon Nanotubes Hybrid Film

Nano Letters. Dec, 2014  |  Pubmed ID: 25402965

The development of portable and wearable electronics has promoted increasing demand for high-performance power sources with high energy/power density, low cost, lightweight, as well as ultrathin and flexible features. Here, a new type of flexible Ni/Fe cell is designed and fabricated by employing Ni(OH)2 nanosheets and porous Fe2O3 nanorods grown on lightweight graphene foam (GF)/carbon nanotubes (CNTs) hybrid films as electrodes. The assembled f-Ni/Fe cells are able to deliver high energy/power densities (100.7 Wh/kg at 287 W/kg and 70.9 Wh/kg at 1.4 kW/kg, based on the total mass of active materials) and outstanding cycling stabilities (retention 89.1% after 1000 charge/discharge cycles). Benefiting from the use of ultralight and thin GF/CNTs hybrid films as current collectors, our f-Ni/Fe cell can exhibit a volumetric energy density of 16.6 Wh/l (based on the total volume of full cell), which is comparable to that of thin film battery and better than that of typical commercial supercapacitors. Moreover, the f-Ni/Fe cells can retain the electrochemical performance with repeated bendings. These features endow our f-Ni/Fe cells a highly promising candidate for next generation flexible energy storage systems.

High-performance Asymmetric Supercapacitors Based on Multilayer MnO2 /graphene Oxide Nanoflakes and Hierarchical Porous Carbon with Enhanced Cycling Stability

Small (Weinheim an Der Bergstrasse, Germany). Mar, 2015  |  Pubmed ID: 25384679

In this work, MnO(2)/GO (graphene oxide) composites with novel multilayer nanoflake structure, and a carbon material derived from Artemia cyst shell with genetic 3D hierarchical porous structure (HPC), are prepared. An asymmetric supercapacitor has been fabricated using MnO(2)/GO as positive electrode and HPC as negative electrode material. Because of their unique structures, both MnO(2)/GO composites and HPC exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high voltage range of 0-2 V in aqueous electrolyte, which exhibits maximum energy density of 46.7 Wh kg(-1) at a power density of 100 W kg(-1) and remains 18.9 Wh kg(-1) at 2000 W kg(-1). Additionally, such device also shows superior long cycle life along with ∼100% capacitance retention after 1000 cycles and ∼93% after 4000 cycles.

A General Approach Towards Multi-faceted Hollow Oxide Composites Using Zeolitic Imidazolate Frameworks

Nanoscale. Jan, 2015  |  Pubmed ID: 25463049

To realize the various functionalities and maximize the structural advantages, hollow particles with multiple compositions and complex structures are highly desirable. However, the development of a convenient and scalable method for the synthesis of such multi-compositionally complex hollow structures remains a big challenge. Herein, we report an efficient and universal strategy to fabricate a variety of porous hollow oxide nanocomposites (Co3O4/SiO2, Co3O4/TiO2, ZnO/SiO2, and ZnO/TiO2) composed of nanosized subunits, which involves a sol-gel process to form a shell onto the dodecahedral zeolitic imidazolate framework (ZIF) template and a subsequent thermolysis-induced transformation of the template at appropriate temperatures. Such a multi-compositional hollow structure with a large surface area endows the materials with exceptional properties and performances. As an example, we demonstrated that these complex hollow oxide composites, especially the Co3O4/SiO2 hollow dodecahedra, exhibit a significantly enhanced photocatalytic performance as oxygen evolution photocatalysts.

Intermode Beating Mode-locking Technique for O-band Mixed-cascaded Raman Fiber Lasers

Optics Letters. Feb, 2015  |  Pubmed ID: 25680135

A novel intermode beating mode-locking (IBML) technique combined with a cascaded Raman process is proposed to mode-lock an O-band two-cascaded Raman fiber laser. Using a 980-m-long phosphosilicate fiber pumped by a 1064 nm laser, the second-order Raman oscillation at 1319 nm is generated by the mixed-cascaded Raman shifts of P2O5 and SiO2. By precisely matching the intermode beating frequencies of the 1064 nm pump laser and the second-order Raman cavity frequency, harmonic mode-locking at 1319 nm is initiated. The dynamic process of the IBML operation in the cascaded Raman laser is experimentally investigated. The 131st-order harmonic mode-locking with a repetition rate of 27.247 MHz is very stable with the radio-frequency (RF) signal-to-noise ratio of >56  dB and the RF supermode-suppression ratio of >43  dB. The mode-locked pulses with the square profile are confirmed as the noise-like pulses by an autocorrelator. The IBML technique, in combination with the cascaded Raman process, could offer an exciting new prospect for obtaining simple, compact, and arbitrary-wavelength mode-locked laser sources.

Direct Generation of 2  W Average-power and 232  nJ Picosecond Pulses from an Ultra-simple Yb-doped Double-clad Fiber Laser

Optics Letters. Mar, 2015  |  Pubmed ID: 25768191

We report the generation of 2.06 W average-power and 232 nJ picosecond mode-locked pulses directly from an ultra-simple Yb-doped fiber laser. A section of Yb-doped double-clad fiber pumped by a 976 nm laser diode provides the large gain, and the linear cavity is simply formed by a 1064 nm highly reflective fiber Bragg grating and a fiber loop mirror (FLM) using a 5/95 optical coupler. The asymmetric FLM not only acts as the output mirror for providing ∼20% optical feedback, but also equivalently behaves as a nonlinear optical loop mirror (NOLM) to initiate the mode-locking operation in this cavity. Stable mode-locking is therefore achieved over a pump power of 3.76 W. The mode-locked pulses show the dissipative soliton resonance (DSR), which has the pulse duration of 695 ps to ∼1  ns, and the almost unchanged peak power of ∼200  W as increasing the pump power. In particular, this laser can emit 232 nJ high-energy DSR pulses with an average output power of >2  W. This is, to the best of our knowledge, the first demonstration of such an ultra-simple, mode-locked fiber laser that enables watt-level, high energy, picosecond DSR pulses.

The Roles of Lithium-philic Giant Nitrogen-doped Graphene in Protecting Micron-sized Silicon Anode from Fading

Scientific Reports. Oct, 2015  |  Pubmed ID: 26497729

A stable Si-based anode with a high initial coulombic efficiency (ICE) for lithium-ion batteries (LIB) is critical for energy storage. In the present paper, a new scalable method is adopted in combination with giant nitrogen-doped graphene and micron-size electrode materials. We first synthesize a new type of freestanding LIB anode composed of micron-sized Si (mSi) particles wrapped by giant nitrogen-doped graphene (mSi@GNG) film. High ICE (>85%) and long cycle life (more than 80 cycles) are obtained. In the mSi@GNG composite, preferential formation of a stable solid electrolyte interphase (SEI) on the surface of graphene sheets is achieved. The formation and components of SEI are identified for the first time by using UV-resonance Raman spectroscopy and Raman mapping, which will revive the study of formation and evolution of SEI by Raman. New mechanism is proposed that the giant graphene sheets protect the mSi particles from over-lithiation and fracture. Such a simple and scalable method may also be applied to other anode systems to boost their energy and power densities for LIB.

General Approach for MOF-Derived Porous Spinel AFe2O4 Hollow Structures and Their Superior Lithium Storage Properties

ACS Applied Materials & Interfaces. Dec, 2015  |  Pubmed ID: 26572743

A general and simple approach for large-scale synthesis of porous hollow spinel AFe2O4 nanoarchitectures via metal organic framework self-sacrificial template strategy is proposed. By employing this method, we can successfully synthesize uniform NiFe2O4, ZnFe2O4, and CoFe2O4 hollow architectures that are hierarchically assembled by nanoparticles. When these hollow microcubes were tested as anode for lithium ion batteries, good rate capability and long-term cycling stability can be achieved. For example, high specific capacities of 636, 449, and 380 mA h g(-1) were depicted by NiFe2O4, ZnFe2O4, and CoFe2O4, respectively, at a high current density of 8.0 A g(-1). NiFe2O4 exhibits high specific capacities of 841 and 447 mA h g(-1) during the 100th cycle when it was tested at current densities of 1.0 and 5.0 A g(-1), respectively. Discharge capacities of 390 and 290 mA h g(-1) were delivered by the ZnFe2O4 and CoFe2O4, respectively, during the 100th cycle at 5.0 A g(-1).

Low-loss Photonic Device in Ge-Sb-S Chalcogenide Glass

Optics Letters. Jul, 2016  |  Pubmed ID: 27367109

Low-loss waveguides constitute an important building block for integrated photonic systems. In this work, we investigated low-loss photonic device fabrication in Ge23Sb7S70 chalcogenide glass using electron beam lithography followed by plasma dry etching. High-index-contrast waveguides with a low propagation loss of 0.5 dB/cm and microdisk resonators with an intrinsic quality factor (Q-factor) of 1.2×106 were demonstrated. Both figures represent, to the best of our knowledge, the best low-loss results reported thus far in submicrometer single-mode chalcogenide glass devices.

Gradient Polymer Nanofoams for Encrypted Recording of Chemical Events

ACS Nano. Dec, 2016  |  Pubmed ID: 27754643

We have fabricated gradient-grafted nanofoam films that are able to record the presence of volatile chemical compounds in an offline regime. In essence, the nanofoam film (100-300 nm thick) is anchored to a surface cross-linked polymer network in a metastable extended configuration that can relax back to a certain degree upon exposure to a chemical vapor. The level of the chain relaxation is associated with thermodynamic affinity between the polymer chains and the volatile compounds. In our design, the chemical composition of the nanofoam film is not uniform; therefore, the film possesses a gradually changing local affinity to a vapor along the surface. Upon vapor exposure, the nonuniform changes in local film morphology provide a permanent record or "fingerprint" for the chemical event of interest. This permanent modification in the film structure can be directly detected via changes not only in the film surface profile but also in the film optical characteristics. To this end, we demonstrated that sensing/recording nanofoam films can be prepared and interrogated on the surfaces of optical waveguides, microring optical resonators. It is important that the initial surface profile and structure of the nanofoam film are encrypted by the distinctive conditions that were used to fabricate the film and practically impossible to replicate without prior knowledge.

New Insight into the Roles of Oxygen Vacancies in Hematite for Solar Water Splitting

Physical Chemistry Chemical Physics : PCCP. Jan, 2017  |  Pubmed ID: 27858025

Oxygen vacancies play an important role in the performance improvement of oxide semiconductors as photoanodes for water splitting, such as TiO2, WO3, and Fe2O3. Conductivity improvement due to the presence of oxygen vacancies was reported to be the main reason for the enhanced performance. However, oxygen vacancies may also affect light absorption and charge transfer through the solid/electrolyte interface. The roles of oxygen vacancies have not been thoroughly discussed in the past. Herein, with hematite as an example, the effects of oxygen vacancies on bulk charge transport and surface catalysis are quantitatively analyzed by decoupling photon absorption, interfacial charge transfer and charge separation processes. Oxygen vacancies improve the charge separation of both pristine and Ti-doped hematite. However, opposite observations are found in the charge transfer process for pristine and Ti-doped hematite: the positive effect in pristine hematite but the negative effect in the Ti-doped one. An electrochemical technique is used to analyze the different influences on pristine and Ti-doped hematite to unravel the mechanism of the opposite observations caused by oxygen vacancies. The current study sheds lights on how oxygen vacancies affect various aspects of important factors behind PEC performance, which is helpful to the development of more efficient photoanodes in the future.

Large-Area and High-Quality 2D Transition Metal Telluride

Advanced Materials (Deerfield Beach, Fla.). Jan, 2017  |  Pubmed ID: 27859781

Large-area and high-quality 2D transition metal tellurides are synthesized by the chemical vapor deposition method. The as-grown WTe2 maintains two different stacking sequences in the bilayer, where the atomic structure of the stacking boundary is revealed by scanning transmission electron microscopy. The low-temperature transport measurements reveal a novel semimetal-to-insulator transition in WTe2 layers and an enhanced superconductivity in few-layer MoTe2 .

The Electrochemical Response of Single Crystalline Copper Nanowires to Atmospheric Air and Aqueous Solution

Small (Weinheim an Der Bergstrasse, Germany). Mar, 2017  |  Pubmed ID: 28026122

In this paper, single crystalline copper nanowires (CuNWs) have been electrochemically grown through anodic aluminum oxide template. The environmental stability of the as-obtained CuNWs in both 40% relative humidity (RH) atmosphere and 0.1 m NaOH aqueous solution has been subsequently studied. In 40% RH atmosphere, a uniform compact Cu2 O layer is formed as a function of exposure time following the logarithmic law and epitaxially covers the CuNW surfaces. It is also found that the oxide layers on CuNWs are sequentially grown when subjected to the cyclic voltammetry measurement in 0.1 m NaOH solution. An epitaxially homogeneous Cu2 O layer is initially formed over the surface of the CuNW substrates by solid-state reaction (SSR). Subsequently, the conversion of Cu2 O into epitaxial CuO based on the SSR takes place with the increase of applied potential. This CuO layer is partially dissolved in the solution forming Cu(OH)2 , which then redeposited on the CuNW surfaces (i.e., dissolution-redeposition (DR) process) giving rise to a mixed polycrystalline CuO/Cu(OH)2 layer. The further increase of applied potential allows the complete oxidation of Cu2 O into CuO to form a dual-layer structure (i.e., CuO inner layer and Cu(OH)2 outer layer) with random orientations through an enhanced DR process.

Nickel Nanoparticles Encapsulated in Few-Layer Nitrogen-Doped Graphene Derived from Metal-Organic Frameworks As Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Advanced Materials (Deerfield Beach, Fla.). Mar, 2017  |  Pubmed ID: 28102612

Nickel nanoparticles encapsulated in few-layer nitrogen-doped graphene (Ni@NC) are synthesized by using a Ni-based metal-organic framework as the precursor for high-temperature annealing treatment. The resulting Ni@NC materials exhibit highly efficient and ultrastable electrocatalytic activity toward the hydrogen evolution reaction and the oxygen evolution reaction as well as overall water splitting in alkaline environment.

1.2-W Average-power, 700-W Peak-power, 100-ps Dissipative Soliton Resonance in a Compact Er:Yb Co-doped Double-clad Fiber Laser

Optics Letters. Feb, 2017  |  Pubmed ID: 28146501

Mode-locked pulses in the dissipative soliton resonance (DSR) regime enable extremely high pulse energy, but typically have the limited peak power of <100  W and a nanosecond-long pulse duration. In this Letter, we demonstrate high-peak-power, ultrashort DSR pulses in a compact Er:Yb co-doped double-clad fiber laser. The linear cavity is simply formed by two fiber loop mirrors (FLMs) using a 50/50 optical coupler (OC) and a 5/95 OC. The 5/95 FLM with a short loop length of 3 m is not only used as the output mirror, but also acts as a nonlinear optical loop mirror for initiating high-peak-power DSR. In particular, the mode-locked laser can deliver ∼100  ps DSR pulses with a maximum average power of 1.2 W and a peak power as high as ∼700  W. This is, to the best of our knowledge, the highest peak power of DSR pulses obtained in mode-locked fiber lasers.

Gamma Radiation Effects in Amorphous Silicon and Silicon Nitride Photonic Devices

Optics Letters. Feb, 2017  |  Pubmed ID: 28146534

Understanding radiation damage is of significant importance for devices operating in radiation-harsh environments. In this Letter, we present a systematic study on gamma radiation effects in amorphous silicon and silicon nitride guided wave devices. It is found that gamma radiation increases the waveguide modal effective indices by as much as 4×10-3 in amorphous silicon and 5×10-4 in silicon nitride at 10 Mrad dose. This Letter further reveals that surface oxidation and radiation-induced densification account for the observed index change.

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