Porous 2D Catalyst Covers Improve Photoelectrochemical Water-oxidation Performance

Confined catalysis under the cover of two-dimensional (2D) materials has emerged as a promising approach for achieving highly effective catalysts in various essential reactions. Here, a porous cover structure is designed to boost the interfacial charge and mass transfer kinetics of 2D-covered catalysts. The improvement in catalytic performance is confirmed by the photoelectrochemical oxidation evolution reaction (OER) on a photoanode based on an n-Si substrate modified with a NiO_x thin-film model electrocatalyst covered with a porous graphene (pGr) monolayer. Experimental results demonstrate that the pGr cover enhances the OER kinetics by balancing the charge and mass transfer at the photoanode and electrolyte interface compared to the intrinsic graphene cover and cover-free control samples. Theoretical investigations further corroborate that the pore edges of the pGr cover boost the intrinsic catalytic activity of active sites on NiO_x by reducing the reaction overpotential. Furthermore, the optimized pores, which can be easily controlled by plasma bombardment, allow oxygen molecules produced in the OER to pass through without peeling off the pGr cover, thus ensuring the structural stability of the catalyst. This study highlights the significant role of the porous cover structure in 2D-covered catalysts and provides new insight into the design of high-performance catalysts. This article is protected by copyright. All rights reserved.

A facile covalent strategy for ultrafast negative photoconductance hybrid graphene/porphyrin-based photodetector

As a powerful complement to positive photoconductance (PPC), negative photoconductance (NPC) holds great potential for photodetector. However, the slow response of NPC relative to PPC devices limits their integration. Here, we propose a facile covalent strategy for an ultrafast NPC hybrid 2D photodetector. Our transistor-based graphene/porphyrin model device with a rise time of 0.2 ms and decay time of 0.3 ms has the fastest response time in the so far reported NPC hybrid photodetectors, which is attributed to efficient photogenerated charge transport and transfer. Both the photosensitive porphyrin with an electron-rich and large rigid structure and the built-in graphene frame with high carrier mobility are prone to the photogenerated charge transport. Especially, the intramolecular donor-acceptor system formed by graphene and porphyrin through covalent bonding promotes photoinduced charge transfer. This covalent strategy can be applied to other nanosystems for high-performance NPC hybrid photodetector.

Nanoarray Structures for Artificial Photosynthesis

Conversion and storage of solar energy into fuels and chemicals by artificial photosynthesis has been considered as one of the promising methods to address the global energy crisis. However, it is still far from the practical applications on a large scale. Nanoarray structures that combine the advantages of nanosize and array alignment have demonstrated great potential to improve solar energy conversion efficiency, stability, and selectivity. This article provides a comprehensive review on the utilization of nanoarray structures in artificial photosynthesis of renewable fuels and high value-added chemicals. First, basic principles of solar energy conversion and superiorities of using nanoarray structures in this field are described. Recent research progress on nanoarray structures in both abiotic and abiotic-biotic hybrid systems is then outlined, highlighting contributions to light absorption, charge transport and transfer, and catalytic reactions (including kinetics and selectivity). Finally, conclusions and outlooks on future research directions of nanoarray structures for artificial photosynthesis are presented.

Modification of interface and electronic transport in van der Waals heterojunctions by UV/O3

Two-dimensional (2D) van der Waals heterojunctions have many unique properties, and energy band modulation is central to applying these properties to electronic devices. Taking the 2D graphene/MoS₂heterojunction as a model system, we demonstrate that the band structure can be finely tuned by changing the graphene structure of the 2D heterojunction via ultraviolet/ozone (UV/O₃). With increasing UV/O₃exposure time, graphene in the heterojunction has more defect structures. The varied defect levels in graphene modulate the interfacial charge transfer, accordingly the band structure of the heterojunction. And the corresponding performance change of the graphene/MoS₂field effect transistor indicates the shift of the Schottky barrier height after UV/O₃treatment. The result further proves the effective band structure modulation of the graphene/MoS₂heterojunction by UV/O₃. This work will be beneficial to both fundamental research and practical applications of 2D van der Waals heterojunction in electronic devices.

Selective Growth of Stacking Fault Free ⟨100⟩ Nanowires on a Polycrystalline Substrate for Energy Conversion Application

Cubic semiconductor nanowires grown along ⟨100⟩ directions have been reported to be promising for optoelectronics and energy conversion applications, owing to their pure zinc-blende structure without any stacking fault. But, until date, only limited success has been achieved in growing ⟨100⟩ oriented nanowires. Here we report the selective growth of stacking fault free ⟨100⟩ nanowires on a commercial transparent conductive polycrystalline fluorine-doped SnO₂ (FTO) glass substrate via a simple and cost-effective chemical vapor deposition (CVD) method. By means of crystallographic analysis and density functional theory calculation, we prove that the orientation relationship between the Au catalyst and the FTO substrate play a vital role in inducing the selective growth of ⟨100⟩ nanowires, which opens a new pathway for controlling the growth directions of nanowires via the elaborate selection of the catalyst and substrate couples during the vapor-solid-liquid (VLS) growth process. The ZnSe nanowires grown on the FTO substrate are further applied as a photoanode in photoelectrochemical (PEC) water splitting. It exhibits a higher photocurrent than the ZnSe nanowires do without preferential orientations on a Sn-doped In₂O₃ (ITO) glass substrate, which we believe to be correlated with the smooth transport of charge carriers in ZnSe ⟨100⟩ nanowires with pure zinc-blende structures, in distinct contrast with the severe electron scattering happened at the stacking faults in ZnSe nanowires on the ITO substrate, as well as the efficient charge transfer across the intensively interacting nanowire-substrate interfaces.

Two-Dimensional Covalent Organic Framework-Graphene Photodetectors: Insight into the Relationship between the Microscopic Interfacial Structure and Performance

Graphene is an attractive material for photodetection and optoelectronic applications because it offers a broad spectral bandwidth and ultrafast response speed. However, because of the broad light absorption characteristic, graphene has a lack of selectivity to the wavelength, which limits the performance of graphene-based photodetectors. Here, we demonstrate a novel hybrid photodetector with monolayer graphene covered with an ultrathin film of surface covalent organic frameworks (COFs) with variable structures as the light-harvesting materials. Photodetectors based on surface COF-G show enhanced responsivity in comparison with unmodified graphene and graphene modified with monomers. The submolecular resolution of scanning tunneling microscopy allows us to get a direct insight into the relationship between the microscopic interfacial structure and the performance of the device. We prove that the enhancement in the device performance is directly related with the orderliness of surface COFs, which influences the interfacial charge transfer by tuning π-π stacking between surface COF and graphene.

Antibacterial Carbon-Based Nanomaterials

The emergence and global spread of bacterial resistance to currently available antibiotics underscore the urgent need for new alternative antibacterial agents. Recent studies on the application of nanomaterials as antibacterial agents have demonstrated their great potential for management of infectious diseases. Among these antibacterial nanomaterials, carbon-based nanomaterials (CNMs) have attracted much attention due to their unique physicochemical properties and relatively higher biosafety. Here, a comprehensive review of the recent research progress on antibacterial CNMs is provided, starting with a brief description of the different kinds of CNMs with respect to their physicochemical characteristics. Then, a detailed introduction to the various mechanisms underlying antibacterial activity in these materials is given, including physical/mechanical damage, oxidative stress, photothermal/photocatalytic effect, lipid extraction, inhibition of bacterial metabolism, isolation by wrapping, and the synergistic effect when CNMs are used in combination with other antibacterial materials, followed by a summary of the influence of the physicochemical properties of CNMs on their antibacterial activity. Finally, the current challenges and an outlook for the development of more effective and safer antibacterial CNMs are discussed.

Improving the Water Oxidation Efficiency with a Light-Induced Electric Field in Nanograting Photoanodes

Severe charge recombination in solar water-splitting devices significantly limits their performance. To address this issue, we design a frustum of a cone nanograting configuration by taking the hematite and Au-based thin-film photoanode as a model system, which greatly improves the photoelectrochemical water oxidation activity, affording an approximately 10-fold increase in the photocurrent density at 1.23 V versus the reversible hydrogen electrode compared to the planar counterpart. The surface plasmon polariton-induced electric field in hematite plays a dominant role in efficiency enhancement by facilitating charge separation, thus dramatically increasing the incident photon-to-current efficiency (IPCE) by more than 2 orders of magnitude in the near band gap of hematite. And the relatively weak electric field caused by light scattering in the nanograting structure is responsible for the approximate maximum 20-fold increase in IPCE within a broadband wavelength range. Our scalable strategy can be generalized to other solar energy conversion systems.

A new nanowire-based lithium hexaoxotungstate anode for lithium-ion batteries

This study reports one dimensional lithium hexaoxotungstate (Li₆WO₆), with a diameter in the range of 200-500 nm, as a novel anode material for lithium-ion batteries. The electrochemical performance of lithium hexaoxotungstate was investigated and a discharge capacity of 705 mA h g^-1 was achieved after 50 cycles, along with an excellent rate capability. The 1D morphology of the material is believed to provide excellent transport properties, resulting in a high rate capability. The remarkable electrochemical performance of the Li₆WO₆ nanowires indicates that this new class of anode holds a lot of promise for future deployment in energy storage devices.

Interaction-Dependent Interfacial Charge-Transfer Behavior in Solar Water-Splitting Systems

Dual-band-gap systems are promising for solar water splitting due to their excellent light-harvesting capability and high charge-separation efficiency. However, a fundamental understanding of interfacial charge-transfer behavior in the dual-band-gap configuration is still incomplete. Taking CdS/reduced graphene oxide (CdS/RGO) nanoheterojunctions as a model solar water splitting system, we attempt here to highlight the interaction-dependent interfacial charge-transfer behavior based on both experimental observations and theoretical calculations. Experimental evidence points to charge transfer at the CdS-RGO interface playing a dominant role in the photocatalytic hydrogen production activity. By tuning the degree of reduction of RGO, the interfacial interaction, and, thereby, the charge transfer can be controlled at the CdS-RGO interface. This observation is supported by theoretical analysis, where we find that the interfacial charge transfer is a balance between the effective single-electron- and hole-transfer probability and the surface free electron and hole concentration, both of which are related to the surface potential and tailored by interfacial interaction. This mechanism is applicable to all systems for solar water splitting, providing a useful guidance for the design and study of heterointerfaces for high-efficiency energy conversion.

Vertically Aligned Porous Organic Semiconductor Nanorod Array Photoanodes for Efficient Charge Utilization

Because of inefficient charge utilization caused by localized π-electron conjugation and large exciton binding energy, the photoelectrochemical water-splitting efficiency of organic polymers is seriously limited. Taking the graphitic carbon nitride (g-CN) polymer as an example, we report a novel photoanode based on a vertically aligned g-CN porous nanorod (PNR) array prepared in situ, using a thermal polycondensation approach, with anodic aluminum oxide as the template. The g-CN PNR array exhibits an excellent photocurrent density of 120.5 μA cm^-2 at 1.23 V_RHE under one sun illumination, the highest reported incident photon-to-current efficiency of ∼15% at 360 nm, and an outstanding oxygen evolution reaction stability in 0.1 M Na₂SO₄ aqueous solution, which constitutes a benchmark performance among the reported g-CN-based polymer photoanodes without any sacrificial reagents. When compared with its planar counterpart, the enhanced performance of the PNR array results principally from its unique structure that enables a high degree of aromatic ring π-electron conjugation for higher mobility of charge carriers, provides a direct pathway for the electron transport to the substrate, produces a large portion of hole-accepting defect sites and space charge region to promote exciton dissociation, and also withstands more strain at the interface to ensure intimate contact with the substrate. This work opens a new avenue to develop nanostructured organic semiconductors for large-scale application of solar energy conversion devices.

Low-Temperature and Fast Kinetics for CO2 Sorption Using Li6WO6 Nanowires

In this paper, lithium hexaoxotungstate (Li₆WO₆) nanowires were synthesized via facile solid-state reaction and were tested for CO₂ capture applications at both low (<100 °C) and high temperatures (>700 °C). Under dry conditions, the nanowire materials were able to capture CO₂ with a weight increment of 12% in only 60 s at an operating temperature of 710 °C. By contrast, under humidified ambience, Li₆WO₆ nanowires capture CO₂ with weight increment of 7.6% at temperatures as low as 30-40 °C within a time-scale of 1 min. It was observed that the CO₂ chemisorption in Li₆WO₆ is favored in the oxygen ambience at higher temperatures and in the presence of water vapor at lower temperatures. Nanowire morphology favors the swift lithium supply to the surface of lithium-rich Li₆WO₆, thereby enhancing the reaction kinetics and lowering time scales for high capacity adsorption. Overall, high chemisorption capacities, superfast reaction kinetics, wide range of operating temperatures, and reasonably good recyclability make 1-D Li₆WO₆ materials highly suitable for various CO₂ capture applications.

Facile Integration between Si and Catalyst for High-Performance Photoanodes by a Multifunctional Bridging Layer

Designing high-quality interfaces is crucial for high-performance photoelectrochemical (PEC) water-splitting devices. Here, we demonstrate a facile integration between polycrystalline n⁺p-Si and NiFe-layered double hydroxide (LDH) nanosheet array by a partially activated Ni (Ni/NiO_x) bridging layer for the excellent PEC water oxidation. In this model system, the thermally deposited Ni interlayer protects Si against corrosion and makes good contact with Si, and NiO_x has a high capacity of hole accumulation and strong bonding with the electrodeposited NiFe-LDH due to the similarity in material composition and structure, facilitating transfer of accumulated holes to the catalyst. In addition, the back illumination configuration makes NiFe-LDH sufficiently thick for more catalytically active sites without compromising Si light absorption. This earth-abundant multicomponent photoanode affords the PEC performance with an onset potential of ∼0.78 V versus reversible hydrogen electrode (RHE), a photocurrent density of ∼37 mA cm^-2 at 1.23 V versus RHE, and retains good stability in 1.0 M KOH, the highest water oxidation activity so far reported for the crystalline Si-based photoanodes. This bridging layer strategy is efficient and simple to smooth charge transfer and make robust contact at the semiconductor/electrocatalyst interface in the solar water-splitting systems.

Nitrogen-doped graphene quantum dots coupled with photosensitizers for one-/two-photon activated photodynamic therapy based on a FRET mechanism

Photosensitizers can be excited by nitrogen-doped graphene quantum dots under one-/two-photon excitation through an intramolecular FRET mechanism and induced phototoxicity.

Sacrificial Interlayer for Promoting Charge Transport in Hematite Photoanode

The semiconductor/electrolyte interface plays a crucial role in photoelectrochemical (PEC) water-splitting devices as it determines both thermodynamic and kinetic properties of the photoelectrode. Interfacial engineering is central for the device performance improvement. Taking the cheap and stable hematite (α-Fe₂O₃) wormlike nanostructure photoanode as a model system, we design a facile sacrificial interlayer approach to suppress the crystal overgrowth and realize Ti doping into the crystal lattice of α-Fe₂O₃ in one annealing step as well as to avoid the consequent anodic shift of the photocurrent onset potential, ultimately achieving five times increase in its water oxidation photocurrent compared to the bare hematite by promoting the transport of charge carriers, including both separation of photogenerated charge carriers within the bulk semiconductor and transfer of holes across the semiconductor-electrolyte interface. Our research indicates that understanding the semiconductor/electrolyte interfacial engineering mechanism is pivotal for reconciling various strategies in a beneficial way, and this simple and cost-effective method can be generalized into other systems aiming for efficient and scalable solar energy conversion.

[Effects of Oridonin combined with Capecitabine on the proliferaction of MDA-MB-231 human breast cancer cells]

Objective: To investigate the effects of oridonin combined with capecitabine on the proliferaction of MDA-MB-231 human breast cancer cells. Methods: Effect of different concentrations(10, 20 and 40 μmol/L)of oridonin, capecitabine and their combination on the proliferation of MDA-MB-231 cells after incubation for 24 or 48 h was studied. Then, the effect of 5 μmol/L of oridonin, capecitabine and their combination on cell colony formation was detected. Finally, influence of 20 μmol/L of oridonin, capecitabine and their combination on morphological alteration of nucleus, cell cycle and apoptosis was explored. Results: The inhibition rate on MDA-MB-231 cells after incubation with 20 μmol/L oridonin or capecitabine for 48 h was 49.5% and 58.6%, respectively, while the inhibition rate against proliferation of MDA-MB-231 cells reached 94.6% with combination of 20 μmol/L oridonin and capecitabine. Cells incubated with combination of oridonin and capecitabine formed fewer and smaller colonies (P<0.01). Meanwhile, cells in the combination group arrested at S and G2/M phases at the same time, and combination of two drugs caused more apoptotic cells (P<0.01). Conclusion: Oridonin combined with capecitabine can synergistically inhibit the proliferation of MDA-MB-231 human breast cancer cells.

Chiral Nanoparticle as a New Efficient Antimicrobial Nanoagent

d-type functionalized nanoparticles (NPs) can bind to MurD ligase with high affinity and inhibit its peptidoglycan synthetic enzyme activity, and finally cause bacterial killing. In contrast, its L-type counterpart displays a negligible effect, indicating that the chiral structure of the functionalized NPs plays an essential role in their binding interaction with MurD and therefore the antibacterial activity.

Electron spin resonance and fluorescence imaging assisted electrochemical approach for accurate and comprehensive monitoring of cellular hydrogen peroxide dynamics

A new analytical system combining electrochemistry, ESR, and fluorescence imaging for accurately and comprehensively measuring the dynamics of cellular H₂O₂.

[Quantitative analysis of pathological voice and identification with artificial neural network]

Objective:To discuss the characteristic of the clinical pathological voice and the feasibility of computer automatic identification of pathological voice.Method:A total of 129 clinical patients with polyp of vocal cord were selected as the pathological voice group, while a total of 125 people with normal voice were selected from the community as the control group. Praat software was used to collect and analyze the related acoustic parameter values of two groups of cases, including Jitter, Shimmer, harmonic to noise ratio (HNR), signal to noise ratio (SNR), and normalized noise energy (NNE). Pathological voice group and control group were used as training set and testing set for neural network testing, and another 140 cases of pathological voice and normal voice data were selected as a validation set. SPSS Modeler was used for artificial neural network reconstruction to calculate the identification rate of pathological voice. Result:This study found according to the calculation of groups with different genders that Jitter, Shimmer and NNE were increased in pathological voice group compared with the normal group (P< 0.05), while HNR and SNR were decreased compared with the normal group (P< 0.05). Recognition rate of artificial neural network model on pathological voice is 75.7%.Conclusion:Objective voice analysis is helpful in the identification of pathological voice. Artificial neural network has higher accuracy in recognition of pathological voice, with good clinical application value.

Extracellular Biocoordinated Zinc Nanofibers Inhibit Malignant Characteristics of Cancer Cell

Inhibition of the heat shock proteins (HSPs) has been considered to be one of the promising strategies for cancer treatment. However, developing highly effective HSP inhibitors remains a challenge. Recent studies on the evolutionarily distinct functions between intracellular and extracellular HSPs (eHSPs) trigger a new direction with eHSPs as chemotherapeutic targets. Herein, the first engineered eHSP nanoinhibitor with high effectiveness is reported. The zinc-aspartic acid nanofibers have specific binding ability to eHSP90, which induces a decrease in the level of the tumor marker-gelatinases, consequently resulting in downregulation of the tumor-promoting inflammation nuclear factor-kappa B signaling, and finally inhibiting cancer cell proliferation, migration, and invasion; while they are harmless to normal cells. Our findings highlight the potential for cancer treatment by altering the key determinants that shape its ability to adapt and evolve using novel nanomaterials.

Transgenerational safety of nitrogen-doped graphene quantum dots and the underlying cellular mechanism in Caenorhabditis elegans

Nitrogen-doped graphene quantum dots (N-GQDs) are safe for environmental release.

Graphene-based materials for hydrogen generation from light-driven water splitting

Hydrogen production from solar water splitting has been considered as an ultimate solution to the energy and environmental issues. Over the past few years, graphene has made great contribution to improving the light-driven hydrogen generation performance. This article provides a comprehensive overview of the recent research progress on graphene-based materials for hydrogen evolution from light-driven water splitting. It begins with a brief introduction of the current status and basic principles of hydrogen generation from solar water splitting, and tailoring properties of graphene for application in this area. Then, the roles of graphene in hydrogen generation reaction, including an electron acceptor and transporter, a cocatalyst, a photocatalyst, and a photosensitizer, are elaborated respectively. After that, the comparison between graphene and other carbon materials in solar water splitting is made. Last, this review is concluded with remarks on some challenges and perspectives in this emerging field.

TiO2 single crystal with four-truncated-bipyramid morphology as an efficient photocatalyst for hydrogen production

Diverse titanium dioxide (TiO2 ) nanostructures have attracted much attention recently due to their potential application in photocatalytic and photovoltaic fields. Here, the synthesis of a TiO2 single crystal with a novel four-truncated-bipyramid morphology is reported for the first time, produced by a simple hydrothermal method. Both peroxo titanic acid precursor and hydrofluoric acid capping agent are essential for the formation of this unique morphology. Moreover, the as-prepared TiO2 photocatalyst exhibits excellent hydrogen production activity from an ethanol-water solution, which is attributed to exposure of both high-energy {001} oxidative and low-energy {101} reductive facets in an optimal ratio. The current findings will contribute greatly to development of more novel photocatalysts with controllable microscopic structures for hydrogen production.

Strong two-photon-induced fluorescence from photostable, biocompatible nitrogen-doped graphene quantum dots for cellular and deep-tissue imaging

Bright two-photon fluorescent probes are highly desirable to be able to optically probe biological activities deep inside living organisms with larger imaging depth, minor autofluorescence background, and less photodamage. In this study, we report the biocompatible nitrogen-doped graphene quantum dots (N-GQDs) as efficient two-photon fluorescent probes for cellular and deep-tissue imaging. The N-GQD was prepared by a facile solvothermal method using dimethylformamide as a solvent and nitrogen source. The two-photon absorption cross-section of N-GQD reaches 48,000 Göppert-Mayer units, which far surpasses that of the organic dyes and is comparable to that of the high performance semiconductor QDs, achieving the highest value ever reported for carbon-based nanomaterials. More importantly, a study of penetration depth in tissue phantom demonstrates that the N-GQD can achieve a large imaging depth of 1800 μm, significantly extending the fundamental two-photon imaging depth limit. In addition, the N-GQD is nontoxic to living cells and exhibits super photostability under repeated laser irradiation. The high two-photon absorption cross-section, large imaging depth, good biocompatibility, and extraordinary photostability render the N-GQD an attractive alternative probe for efficient two-photon imaging in biological and biomedical applications.

Noble metal-free reduced graphene oxide-ZnxCd₁-xS nanocomposite with enhanced solar photocatalytic H₂-production performance

Design and preparation of efficient artificial photosynthetic systems for harvesting solar energy by production of hydrogen from water splitting is of great importance from both theoretical and practical viewpoints. ZnS-based solid solutions have been fully proved to be an efficient visible-light driven photocatalysts, however, the H(2)-production rate observed for these solid solutions is far from exciting and sometimes an expensive Pt cocatalyst is still needed in order to achieve higher quantum efficiency. Here, for the first time we report the high solar photocatalytic H(2)-production activity over the noble metal-free reduced graphene oxide (RGO)-Zn(x)Cd(1-x)S nanocomposite prepared by a facile coprecipitation-hydrothermal reduction strategy. The optimized RGO-Zn(0.8)Cd(0.2)S photocatalyst has a high H(2)-production rate of 1824 μmol h(-1) g(-1) at the RGO content of 0.25 wt % and the apparent quantum efficiency of 23.4% at 420 nm (the energy conversion efficiency is ca. 0.36% at simulated one-sun (AM 1.5G) illumination). The results exhibit significantly improved photocatalytic hydrogen production by 450% compared with that of the pristine Zn(0.8)Cd(0.2)S, and are better than that of the optimized Pt-Zn(0.8)Cd(0.2)S under the same reaction conditions, showing that the RGO-Zn(0.8)Cd(0.2)S nanocomposite represents one of the most highly active metal sulfide photocatalyts in the absence of noble metal cocatalysts. This work creates a green and simple way for using RGO as a support to enhance the photocatalytic H(2)-production activity of Zn(x)Cd(1-x)S, and also demonstrates that RGO is a promising substitute for noble metals in photocatalytic H(2)-production.

Ginsenosides extracted from nanoscale Chinese white ginseng enhances anticancer effect

Ginsenosides, the major chemical composition of Chinese white ginseng (Panax ginseng C. A. Meyer), can inhibit tumor, enhance body immune function, prevent neurodegeneration. In this paper, for the first time we reported that the amount of ginsenosides in the equivalent extraction of the nanoscale Chinese white ginseng particles (NWGP) was 2.5 times more than that of microscale Chinese white ginseng particles (WGP). And the extractions from NWGP (1000 microg/ml) reached a high tumor inhibition of 64% exposed to human lung carcinoma cells (A549) and 74% exposed to human cervical cancer cells (Hela) after 72 h. Our work shows that the nanoscale Chinese WGP greatly improves the bioavailability of ginsenosides.

Kinetics and thermodynamics of heavy metal ions sequestration onto novel Nauclea diderrichii seed biomass

This study reports the sequestration of Cd(II) and Hg(II) using a new biosorbent, Nauclea diderrichii seed biomass. Experimental data obtained were fitted into kinetic and thermodynamic models. Experimental data fitted best into pseudo-second order kinetic model among others. Results obtained kinetically revealed that the biosorption of Cd(II) and Hg(II) using N. diderrichii seed biosorbent increased with increase in temperature. At the highest temperature, which was 333 K, the highest amount of metal biosorbed, q(e), for Cd(II) and Hg(II) obtained were 6.30 and 6.15 mg/g respectively. The biosorption of Cd(II) was kinetically faster than that of Hg(II), the highest initial biosorption rates for Cd(II) and Hg(II) were 56.19 and 4.39 mg/g min respectively. Thermodynamic parameters obtained by Erying equation from this study revealed that the biosorption process was spontaneous, feasible, endothermic with a decrease in the degree of chaos in the biosorption system.

Direct formation of reusable TiO2/CoFe2O4 heterogeneous photocatalytic fibers via two-spinneret electrospinning

A reusable photocatalytic TiO2/CoFe2O4 composite nanofiber was directly formed by using a vertical two-spinneret electrospinning process and sol-gel method, followed by heat treatment at 550 degrees C for 2 h. The high photocatalytic activity of the composite nanofibers depends on the good morphology of the fibers and the appropriate calcination temperature. The crystal structure and magnetic properties of the fibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The photocatalytic activity of the TiO2/CoFe2O4 fibers was investigated through ultraviolet-visible absorbance following the photo-oxidative decomposition of phenol. Meanwhile, the presence of CoFe2O4 not only broadens the response region of visible light, but also enhances the absorbance of UV light. Furthermore, these fibers displayed photocatalytic activity associated with magnetic activity of CoFe2O4 ferrites, allowing easy separated of the photocatalysts after the photo-oxidative process and effectively avoided the secondary pollution of the treated water.

Visible light photocatalytic H₂-production activity of CuS/ZnS porous nanosheets based on photoinduced interfacial charge transfer

Visible light photocatalytic H(2) production through water splitting is of great importance for its potential application in converting solar energy into chemical energy. In this study, a novel visible-light-driven photocatalyst was designed based on photoinduced interfacial charge transfer (IFCT) through surface modification of ZnS porous nanosheets by CuS. CuS/ZnS porous nanosheet photocatalysts were prepared by a simple hydrothermal and cation exchange reaction between preformed ZnS(en)(0.5) nanosheets and Cu(NO(3))(2). Even without a Pt cocatalyst, the as-prepared CuS/ZnS porous nanosheets reach a high H(2)-production rate of 4147 μmol h(-1) g(-1) at CuS loading content of 2 mol % and an apparent quantum efficiency of 20% at 420 nm. This high visible light photocatalytic H(2)-production activity is due to the IFCT from the valence band of ZnS to CuS, which causes the reduction of partial CuS to Cu(2)S and thus enhances H(2)-production activity. This work not only shows a possibility for substituting low-cost CuS for noble metals in the photocatalytic H(2) production but also for the first time exhibits a facile method for enhancing H(2)-production activity by photoinduced IFCT.

Chiral zinc phenylalanine nanofibers with fluorescence

Chiral Zn(II)/D-,L-phenylalanine (Phe) bio-coordination polymer nanofibers with fluorescence were prepared by fast coordination-assisted assembly. The synthetic strategy is based on the fact that the Zn2+ ions were linked to oxygen atoms from carboxylate groups of the D- or L-amino acid by coordination interactions to form the chiral polymers. The Zn(II)/D-,L-Phe nanofibers had homogeneous diameters in the range of 700-900 nm and ultra-long length in several hundred micrometers, and the surface of the fiber was extremely smooth. In addition, the enantiomers of Zn(II)/Phe nanofibers exhibited both optical activity and fluorescent property in the solid state, which has great potential for application in the field of biomimetic nanofabrication and micro-/nano-optoelectronics.

Switchable ternary nanoporous supramolecular network on photo-regulation

Controlled regulation of the switchable behavior of the supramolecular network is central to the potential application in the molecular scale nanodevices. In this work, it is reported that the reversible accommodation of the guest molecules in the nanoporous supramolecular network can be regulated by the UV/visible light. The nanoporous complex template of TCDB/4NN-Macrocycle(trans,trans,trans,trans) with photosensitive units is well-defined. After the UV irradiation, the template can be switched on to encapsulate coronene molecules due to the formation of a new photoisomer(trans,cis,trans,cis) and switched off to expel coronene from the inner cavities under the visible light. The photoregulated switchable multicomponent supramolecular guest-host network provides a novel strategy for fabricating the functional nanodevices at the molecular scale.

Highly efficient visible-light-driven photocatalytic hydrogen production of CdS-cluster-decorated graphene nanosheets

The production of clean and renewable hydrogen through water splitting using photocatalysts has received much attention due to the increasing global energy crises. In this study, a high efficiency of the photocatalytic H(2) production was achieved using graphene nanosheets decorated with CdS clusters as visible-light-driven photocatalysts. The materials were prepared by a solvothermal method in which graphene oxide (GO) served as the support and cadmium acetate (Cd(Ac)(2)) as the CdS precursor. These nanosized composites reach a high H(2)-production rate of 1.12 mmol h(-1) (about 4.87 times higher than that of pure CdS nanoparticles) at graphene content of 1.0 wt % and Pt 0.5 wt % under visible-light irradiation and an apparent quantum efficiency (QE) of 22.5% at wavelength of 420 nm. This high photocatalytic H(2)-production activity is attributed predominantly to the presence of graphene, which serves as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carriers from CdS nanoparticles. This work highlights the potential application of graphene-based materials in the field of energy conversion.

Microstructure and magnetic property of M-type SrRe(x)Fe(12-x)O19 by sol-gel method

Magnetoplumbite-type (M-type) SrRE(x)Fe(12-x)O19 (RE = La and Ce, x = 0-1.0) powders were prepared by a citric acid sol-gel technique and subsequent heat treatment. The crystal structure, grain size and magnetic properties were investigated by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and vibrating sample magnetometer (VSM). The XRD patterns show that SrRE(x)Fe(12-x)O19 (RE = La and Ce) are mainly hexagonal magnetic plumbite structure, and the average grain size of 30-40 nm was calculated using the Scherer's equation based on the XRD spectrum. Substitution of Fe ion by the rare earth La ion causes a significant decrease in intrinsic coercivity (Hc) and a slight decrease in saturation magnetization (Ms) as shown in the magnetization hysteresis loops. However, the Hc rises gradually in a small wave pattern with the increase of doping content of the rare earth Ce. The relation between the crystal structure and magnetic properties was also studied in this work.

Controllable N-doping of graphene

Opening and tuning an energy gap in graphene are central to many electronic applications of graphene. Here we report N-doped graphene obtained by NH3 annealing after N(+)-ion irradiation of graphene samples. First, the evolution of the graphene microstructure was investigated following N(+)-ion irradiation at different fluences using Raman spectroscopy, showing that defects were introduced in plane after irradiation and then restored after annealing in N2 or in NH3. Auger electron spectroscopy (AES) of the graphene annealed in NH3 after irradiation showed N signal, however, no N signal was observed after annealing in N2. Last, the field-effect transistor (FET) was fabricated using N-doped graphene and monitored by the source-drain conductance and back-gate voltage (Gsd-Vg) curves in the measurement. The transport property changed compared to that of the FET made by intrinsic graphene, that is, the Dirac point position moved from positive Vg to negative Vg, indicating the transition of graphene from p-type to n-type after annealing in NH3. Our approach, which provides a physical mechanism for the introduction of defect and subsequent hetero dopant atoms into the graphene material in a controllable fashion, will be promising for producing graphene-based devices for multiple applications.

[The study on the standardization of adults voice acoustic parameters by objective analysis]

OBJECTIVE

To explore the characteristic of normal voice in different age-bracket of Chinese adults and to formulate the normal reference value suited to our country at voice assessment.

METHOD

We divided the adults into the youth, the middle-aged and the old groups, and analyzed normal voice samples with Dr. Speech software and computer multimedia technique and compared the following 5 parameters (Jitter, Shimmer, NNE, Fo and SDFo) of different groups divided according to one's age, sex and vowel.

RESULT

There is difference among the group of age, sex and vowel in most acoustic parameters in the adults.

CONCLUSION

To initiate taking multi-vowels samples and using different normal reference value and multi-parameters analysis according to the difference of age-bracket, sex and vowel in the adults.