Showing papers by "Jun Chen published in 2012"

A leavening strategy to prepare reduced graphene oxide foams.

Abstract: For instance, freestanding graphene macroscopic structures have shown unique catalytic, electrochemical, and mechanical properties together with potential applications in chemical fi lters and electrodes for energy storage devices. [ 6–8 , 11 , 30 ] However, in most cases, during the process of assembling nanometerscale building blocks into macroscopic paper-like structures, the large accessible surface area of 2D graphene sheets is lost. The reason for this is that the individual graphene sheets tend to irreversibly aggregate and restack owing to the strong π π stacking and van der Waals force between the planar basal planes of graphene sheets. This reduces the potential applications of graphene materials in electrochemical electrodes, composite materials, and so on. [ 20 ] Therefore, preventing aggregation of graphene sheets in the macroscopic structures, such that the properties of the individual graphene sheets are not compromised, is a critical challenge in constructing functional graphene-based macroscopic structures. Currently, a number of strategies for preventing aggregation have been developed, which include adding spacers (e.g., surfactants, nanoparticles, polymers), [ 27–36 ] template-assisted growth, [ 37 ] and crumpling the graphene sheets. [ 18 , 38 ] Alternatively, several groups have reported the formation of freestanding 3D graphene-based macroscopic structures without the assistance of any spacers or templates. [ 7 , 39,40 ] For instance, Li and coworkers reported the preparation of freestanding multilayered graphene fi lms by vacuum-assisted fi ltration based on the effective prevention of graphene intersheet restacking. [ 7 ] Shi and coworkers demonstrated the formation of a 3D graphene hydrogel by a hydrothermal method. [ 39 ] However, preparing freestanding and fl exible graphene fi lms with large accessible surface area but

Facile Oxygen Reduction on a Three‐Dimensionally Ordered Macroporous Graphitic C3N4/Carbon Composite Electrocatalyst

Abstract: Honeycomb catalysis: a facile oxygen reduction reaction has been observed on a graphitic C(3)N(4)/carbon catalyst with three-dimensional interconnected macropores (see picture with SiO(2) template). This material not only shows catalytic activity that is comparable to that of commercial Pt/C, but also has much higher organic-fuel tolerance and long-term stability.

BiVO(4)/CeO(2) nanocomposites with high visible-light-induced photocatalytic activity.

Abstract: Preparation of bismuth vanadate and cerium dioxide (BiVO4/CeO2) nanocomposites as visible-light photocatalysts was successfully obtained by coupling a homogeneous precipitation method with hydrothermal techniques. The BiVO4/CeO2 nanocomposites with different mole ratios were synthesized and characterized by X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). Absorption range and band gap energy, which are responsible for the observed photocatalyst behavior, were investigated by UV–vis diffuse reflectance (UV–vis DR) spectroscopy. Photocatalytic activities of the prepared samples were examined by studying the degradation of model dyes Methylene Blue, Methyl Orange, and a mixture of Methylene Blue and Methyl Orange solutions under visible-light irradiation (>400 nm). Results clearly show that the BiVO4/CeO2 nanocomposite in a 0.6:0.4 mol ratio exhibited the highest photocatalytic activity in dye wastewater treatment.

A “skeleton/skin” strategy for preparing ultrathin free-standing single-walled carbon nanotube/polyaniline films for high performance supercapacitor electrodes

Abstract: One of the most critical aspects in the preparation of single-walled carbon nanotubes (SWCNTs)/conducting polymer hybrid electrodes is to improve the energy density without seriously deteriorating their high power capability. Here, we report a “skeleton/skin” strategy for the preparation of free-standing, thin and flexible SWCNT/polyaniline (PANI) hybrid films by a simple in situ electrochemical polymerization method using directly grown SWCNT films with a continuous reticulate structure as template. In situ electrochemical polymerization can achieve effective deposition of PANI onto the surface of SWCNT bundles in the films and control the morphology and microstructure of the SWCNT/PANI hybrid films. In a SWCNT/PANI hybrid film, the directly grown SWCNT film with continuous reticulate architecture acts as the skeleton and PANI layers act as the skin. This unique continuous “skeleton/skin” structure ensures that these hybrid films have much higher conductivity compared to SWCNT/PANI composite films based on post-deposition SWCNT films. Flexible supercapacitors have been fabricated using the SWCNT/PANI hybrid films as both electrodes and charge collectors without metallic current collectors. High energy and power densities (131 W h kg−1 and 62.5 kW kg−1, respectively) have been achieved for the optimized assembly. The high electrical conductivity and flexibility, in combination with continuous porous architecture, suggests that the as-prepared ultrathin free-standing SWCNT/PANI hybrid films have significant potential as promising electrode materials for thin, lightweight and flexible energy storage devices with high performance.

First-Principles Study of Zigzag MoS2 Nanoribbon As a Promising Cathode Material for Rechargeable Mg Batteries

Abstract: Zigzag MoS2 nanoribbon is a promising cathode of rechargeable magnesium batteries. A first-principles study based on density functional theory (DFT) has been carried out on this material concentrating on key issues relating to magnesium adsorption sites, theoretical capacity, and diffusion kinetics. It is found that the Mo top site at the edge of the nanoribbon is favorable for Mg locations. On zigzag MoS2 nanoribbon, a maximum theoretical capacity of 223.2 mAh g–1 could be achieved by double-side Mg adsorptions. Electronic calculations suggest that partial charge transfers occur between the adsorbed Mg atoms and zigzag MoS2 nanoribbon, but meanwhile, the covalent hybridizations are still observable. A Mg diffusion pathway on the zigzag MoS2 nanoribbon is identified as passing two adjacent T sites mediated by the nearest neighboring H site in between. The activation barrier of this process is only 0.48 eV, much reduced from the 2.61 eV of the bulk interlayer migration. The present results give expectation...

Facile polymer-assisted synthesis of LiNi0.5Mn1.5O4 with a hierarchical micro─nano structure and high rate capability

Abstract: We report the facile preparation of spinel type LiNi0.5Mn1.5O4 with hierarchical micro–nano structures (LNMO-HMs) and their application as cathode materials for rechargeable lithium-ion batteries. The LNMO-HMs, which were synthesized through a poly(ethylene glycol) (PEG)-assisted co-precipitation route, have a particle size of 5–10 μm, which are composed of nano-particles with a size of about 200 nm. The effect of PEG on the phase purity and morphology of the LNMO products was studied. It was found that as the molecular weight of PEG increased, the lithium nickel oxide impurity decreased at first and then increased slightly. The average size of the nano-particles also showed a similar trend of first a decrease and then an increase, while the secondary micro-particles were enlarged with longer PEG chains. Raman mapping technology proved that the P4332 phase and the Fd3m phase LNMO coexist in the as-prepared samples, but the latter is the mainstay. When applied as cathode materials for lithium-ion batteries, PEG4000-assisted LNMO-HMs showed a remarkably high rate capability and cycling stability. The deliverable discharge capacity exceeded 120 mAh g−1 at 40 C current rate and the capacity retention approached 89% after 150 cycles at 5 C current rate, showing the potential in the application of high rate discharge.

Temperature Dependence of the Piezoelectric Coefficient in BiMeO3-PbTiO3 (Me = Fe, Sc, (Mg1/2Ti1/2)) Ceramics

Abstract: The piezoelectric coefficient of high temperature piezoelectric ceramics, denoted as Bi(Me)O3-PbTiO3, (Me = Fe, Sc, (Mg1/2Ti1/2)) was investigated as a function of temperature by using a custom-designed test frame. Utilizing laser vibrometry, it was possible to assess the piezoelectric coefficient in situ in the range from room temperature to 500°C. The constraints on the sample geometry as they exist in the commonly used resonance/antiresonance technique such as those encountered during poling were circumvented by the use of the converse piezoelectric effect. Comparison with literature data revealed that the current method is a useful alternative for determining the depolarization temperature (Td), defined as the inflection point in a temperature-dependent d33 plot. Measured Td for each poled specimen was compared with that determined by dielectric permittivity as well as temperature-dependent X-ray diffraction data to understand a possible origin of Td. It was also shown that Td matches with the temperature where the dielectric anomaly initiates, and hence Td from the d33 measurement is consistently lower than that from the dielectric permittivity measurement. It is proposed that this discrepancy in the position of Td is due to the fact that the depolarization occurs in two steps.

Domain wall and interphase boundary motion in a two-phase morphotropic phase boundary ferroelectric: Frequency dispersion and contribution to piezoelectric and dielectric properties

Abstract: In ferroelectric materials, enhanced dielectric and piezoelectric property coefficients are found in compositions near morphotropic phase boundaries (MPBs). The material response in these compositions may be contributed by enhanced intrinsic piezoelectric distortions or increased interface motion, e.g., contributions from domain wall and interphase boundary motion, though the relative effect of these mechanisms in different materials is not yet well understood. One of the major challenges to developing this understanding is the availability and sensitivity of in situ characterization techniques, particularly during the application of cyclic electric fields of subcoercive or weak amplitude, conditions at which the property coefficients are measured. Here, we use time-resolved neutron diffraction to resolve the subtle electric-field-induced crystallographic strain mechanisms in a prototypical MPB composition, 36$%$BiScO${}_{3}$-64$%$PbTiO${}_{3}$, that contains coexisting monoclinic and tetragonal phases. We observe multiple cooperative electromechanical effects including domain wall motion in both the monoclinic and tetragonal phases, interphase boundary motion between the two phases, and electric-field-induced lattice strains. The measured effects span four orders of magnitude in frequency, facilitating the discrimination of intrinsic and extrinsic contributions to properties. Domain wall motion in the monoclinic phase dominates the response, leading to shifts of diffraction peaks as high as 2300 pm/V; these shifts reflect the field-induced changes in average pseudocubic (00$h$) lattice spacing of the monoclinic phase parallel to the electric field. Domain wall motion in the tetragonal phase is also readily apparent and exhibits a degree of frequency dispersion similar to that measured in both the relative permittivity and piezoelectric coefficients at similar conditions.

Carbon nanotube nanoweb-bioelectrode for highly selective dopamine sensing.

Abstract: A highly sensitive and selective dopamine sensor was fabricated with the unique 3D carbon nanotube nanoweb (CNT-N) electrode. The as-synthesised CNT-N was modified by oxygen plasma to graft functional groups in order to increase selective electroactive sites at the CNT sidewalls. This electrode was characterized physically and electrochemically using HRSEM, Raman, FT-IR, and cyclic voltammetry (CV). Our investigations indicated that the O2-plasma treated CNT-N electrode could serve as a highly sensitive biosensor for the selective sensing of dopamine (DA, 1 μM to 20 μM) in the presence of ascorbic acid (AA, 1000 μM).

Facile solvothermal synthesis of CaMn2O4 nanorods for electrochemical oxygen reduction

Abstract: Electrocatalysts for the oxygen reduction reaction (ORR) are of pivotal importance in various fuel cells and metal–air batteries. In this study, we report a facile synthesis of one-dimensional (1D) CaMn2O4 nanostructures and their applications as cheap and active electrocatalysts for the ORR. Marokite CaMn2O4 nanorods with post-spinel phase were prepared by a solvothermal route at mild temperatures, using potassium manganese oxide hydrate and calcium nitrate as the precursors and ethanol as the solvent. The as-prepared nanorods adopted the orthorhombic structure and possessed diameters of 150–300 nm and lengths of 2–4 μm, with preferentially exposed (023) planes on surfaces. In alkaline electrolytes, CaMn2O4 nanorods exhibited considerable catalytic performance and enabled an apparent quasi-four-electron transfer in the ORR, as evidenced by rotating disk electrode and rotating ring-disk electrode studies. The determined Tafel slop and the chronoamperometry stability of CaMn2O4 nanorod electrocatalysts were comparable to the counterpart Pt nanoparticles supported on carbon.

Microstructure and magnetorheological properties of the thermoplastic magnetorheological elastomer composites containing modified carbonyl iron particles and poly(styrene-b-ethylene-ethylenepropylene-b-styrene) matrix

Abstract: Novel isotropic and anisotropic thermoplastic magnetorheological elastomers (MRE) were prepared by melt blending titanated coupling agent modified carbonyl iron (CI) particles with poly(styrene-b-ethylene-ethylene–propylene-b-styrene) (SEEPS) matrix in the absence and presence of a magnetic field, and the microstructure and magnetorheological properties of these SEEPS-based MRE were investigated in detail. The particle surface modification improves the dispersion of the particles in the matrix and remarkably softens the CI/SEEPS composites, thus significantly enhancing the MR effect and improving the processability of these SEEPS-based MRE. A microstructural model was proposed to describe the interfacial compatibility mechanism that occurred in the CI/SEEPS composites after titanate coupling agent modification, and validity of this model was also demonstrated through adsorption tests of unmodified and surface-modified CI particles.

Species Comparison and Pharmacological Characterization of Human, Monkey, Rat, and Mouse TRPA1 Channels

Abstract: The transient receptor potential ankyrin-1 (TRPA1) channel has emerged as an attractive target for development of analgesic and anti-inflammatory drugs. However, drug discovery efforts targeting TRPA1 have been hampered by differences between human and rodent species. Many compounds have been identified to have antagonist activity at human TRPA1 (hTRPA1), but when tested at rat TRPA1 (rTRPA1) and mouse TRPA1 (mTRPA1), they show reduced potency as antagonists, no effect, or agonist activity. These compounds are excluded from further drug development because they cannot be tested in preclinical studies using conventional rat/mouse models. To broaden our understanding of species-specific differences, we cloned and functionally characterized rhesus monkey TRPA1 (rhTRPA1) and compared its pharmacological profile to hTRPA1, rTRPA1, and mTRPA1 channels. The functional activities of a diverse group of TRPA1 ligands (both reactive and nonreactive) were determined in a fluorescent Ca²⁺ influx assay, using transiently transfected human embryonic kidney 293-F cells. 4-Methyl-N-[2,2,2-trichloro-1-(4-nitro-phenylsulfanyl)-ethyl]-benzamide, menthol, and caffeine displayed species-specific differential pharmacology at TRPA1. The pharmacological profile of the rhTRPA1 channel was found to be similar to the hTRPA1 channel. In contrast, the rTRPA1 and mTRPA1 channels closely resembled each other but were pharmacologically distinct from either hTRPA1 or rhTRPA1 channels. Our findings reveal that TRPA1 function differs between primate and rodent species and suggest that rhesus monkey could serve as a surrogate species for humans in preclinical studies.

Evidence for two-gap superconductivity in the non-centrosymmetric compound LaNiC$_2$

Abstract: We study the superconducting properties of the non-centrosymmetric compound LaNiC$_2$ by measuring the London penetration depth $\Delta \lambda (T)$, the specific heat $C(T,B)$ and the electrical resistivity $\rho (T,B)$. Both $\Delta\lambda (T)$ and the electronic specific heat $C_e(T)$ exhibit exponential behavior at low temperatures and can be described in terms of a phenomenological two-gap BCS model. The residual Sommerfeld coefficient in the superconducting state, $\gamma_0(B)$, shows a fast increase at low fields and then an eventual saturation with increasing magnetic field. A pronounced upturn curvature is observed in the upper critical field $B_{c2}(T)$ near $T_{c}$. All the experimental observations support the existence of two-gap superconductivity in LaNiC$_2$.

Novel carbon materials for thermal energy harvesting

Abstract: To decrease the consumption of fossil fuels, research has been done on utilizing low grade heat, sourced from industrial waste streams. One promising thermoenergy conversion system is a thermogalvanic cell; it consists of two identical electrodes held at different temperatures that are placed in contact with a redox-based electrolyte [1, 2]. The temperature dependence of the direction of redox reactions allows power to be extracted from the cell [3, 4]. This study aims to increase the power conversion efficiency and reduce the cost of thermogalvanic cells by optimizing the electrolyte and utilizing a carbon based electromaterial, reduced graphene oxide, as electrodes. Thermal conductivity measurements of the K3Fe(CN)6/K4Fe(CN)6 solutions used, indicate that the thermal conductivity decreases from 0.591 to 0.547 W/m K as the concentration is increased from 0.1 to 0.4 M. The lower thermal conductivity allowed a larger temperature gradient to be maintained in the cell. Increasing the electrolyte concentration also resulted in higher power densities, brought about by a decrease in the ohmic overpotential of the cell, which allowed higher values of short circuit current to be generated. The concentration of 0.4 M K3Fe(CN)6/K4Fe(CN)6 is optimal for thermal harvesting applications using R-GO electrodes due to the synergistic effect of the reduction in thermal flux across the cell and the enhancement of power output, on the overall power conversion efficiency. The maximum mass power density obtained using R-GO electrodes was 25.51 W/kg (three orders of magnitude higher than platinum) at a temperature difference of 60 °C and a K3Fe(CN)6/K4Fe(CN)6 concentration of 0.4 M.

Synthesis and Characterization of Energetic 3‐Nitro‐1,2,4‐oxadiazoles

Abstract: All new: 3-Nitro-5-guanidino-1,2,4-oxadiazole (NOG) was synthesized from diaminoglycoluril with in situ generated dimethyldioxirane (DMDO). The impact sensitivity of NOG is more than 40 J with a decomposition temperature of 290 °C. Some other energetic derivatives have been prepared and characterized.

Reduced graphene oxide and method of producing same

Abstract: There is provided a method of producing reduced (rGO) or partially reduced (prGO) Graphene Oxide films that have improved conductivity. The method is capable of creating highly conducting (-2000 S/cm), flexible, printable, processable reduced graphene oxide materials without the need for harsh chemical treatment or high temperature annealing. In one embodiment, an electrical circuit consisting of reduced graphene oxide tracks may be patterned into a graphene oxide film by printing with a reducing agent, preferably ascorbic acid.

Impact of mechanical bending on the electrochemical performance of bendable lithium batteries with paper-like free-standing V2O5–polypyrrole cathodes

Abstract: Highly flexible, paper-like, free-standing V2O5 and V2O5–polypyrrole (PPy) films were prepared via the vacuum filtration method. The films are soft, lightweight, and mechanically robust. The electrochemical performance of the free-standing pure V2O5 electrode was improved by incorporating conducting polypyrrole. A bendable cell with a novel design was fabricated, consisting of a free-standing V2O5–PPy cathode film, gel electrolyte, and a lithium foil anode. The cell was tested under repeated bending conditions for several cycles. The results show that the battery performance of the repeatedly bent cell was similar to that of the conventional cell.

Deaging and asymmetric energy landscapes in electrically biased ferroelectrics.

Abstract: In ferroic materials, the dielectric, piezoelectric, magnetic, and elastic coefficients are significantly affected by the motion of domain walls. This motion can be described as the propagation of a wall across various types and strengths of pinning centers that collectively constitute a force profile or energetic landscape. Biased domain structures and asymmetric energy landscapes can be created through application of high fields (such as during electrical poling), and the material behavior in such states is often highly asymmetric. In some cases, this behavior can be considered as the electric analogue to the Bauschinger effect. The present Letter uses time-resolved, high-energy x-ray Bragg scattering to probe this asymmetry and the associated deaging effect in the ferroelectric morphotropic phase boundary composition 0.36BiScO(3)-0.64PbTiO(3).

Navitoclax (ABT-263) and bendamustine ± rituximab induce enhanced killing of non-Hodgkin's lymphoma tumours in vivo

Abstract: BACKGROUND AND PURPOSE Bendamustine with or without rituximab provides an effective and more tolerable alternative to the polytherapy cyclophosphamide–doxorubicin–vincristine–prednisolone (CHOP) in the treatment of haematological tumours and is currently approved for the treatment of many haematological malignancies. Navitoclax (ABT-263) is a potent inhibitor of Bcl-2, Bcl-xL and Bcl-w, which has demonstrated efficacy in haematological tumours alone and in combination with other agents. This paper describes the in vivo efficacy of combining either bendamustine or bendamustine plus rituximab (BR) with navitoclax in xenograft models of non-Hodgkin's lymphoma EXPERIMENTAL APPROACH Activity was tested in xenograft models of diffuse large B-cell lymphoma (DoHH-2, SuDHL-4), mantle cell lymphoma (Granta 519) and Burkitt's lymphoma (RAMOS). Activity was also monitored in a systemic model of Granta 519. KEY RESULTS Navitoclax potentiated bendamustine activity in all cell lines tested. Bendamustine activated p53 in Granta 519 tumours, concurrent with activation of caspase 3. Navitoclax also improved responses to bendamustine-rituximab (BR) in a subset of tumours. CONCLUSIONS AND IMPLICATIONS Navitoclax in combination with bendamustine and BR is a viable combination strategy for use in the clinic and demonstrated superior efficacy compared with previously reported data for navitoclax plus CHOP and rituximab-CHOP.

Water-soluble graphene sheets with large optical limiting response via non-covalent functionalization with polyacetylenes

Abstract: Water-soluble graphene sheet was prepared via chemical reduction of graphene oxide (GO) in the presence of polyacetylene bearing a quaternary ammonium pendant (Pac), with a relatively low feed ratio of 1/3 (Pac/GO, w/w). The non-covalent functionalization of graphene by Pac was mainly based on the electrostatic attraction and π–π interaction, the resultant material G–Pac showed good solubility in water with the concentration of 0.28 mg mL−1. In virtue of the unique sp2-conjugated structure of graphene, it displayed a prominent optical limiting response, which could be potentially used in photonic or optoelectronic devices to protect human eyes or optical sensors from damage by intense laser irradiation.

High piezoelectric performance in a new Bi-based perovskite of (1−x)Bi(Ni1/2Hf1/2)O3−xPbTiO3

Abstract: Preparation, piezoelectric, and dielectric properties were investigated in a new Bi-based piezoelectric material of (1−x)Bi(Ni1/2Hf1/2)O3-xPbTiO3. The system can form a pure perovskite structure with the morphotropic phase boundary locating at x = 0.62, separating the rhombohedral and tetragonal phases. It is interesting to observe that the morphotropic phase boundary composition shows a very high piezoelectric coefficient of d33 (446 pC/N), which is comparable to BiScO3-PbTiO3 (460 pC/N). The Curie temperature of the morphotropic phase boundary is around 290 °C. Furthermore, the system has a relatively low coercive field, which makes the poling easily. Temperature dependence of dielectric properties also shows that the Bi(Ni1/2Hf1/2)O3-PbTiO3 system has a strong relaxor feature. Present new Bi-based perovskite of Bi(Ni1/2Hf1/2)O3-PbTiO3 is a competitive piezoelectric material with high piezoelectric performance.

Protection against Mycobacterium tuberculosis challenge in mice by DNA vaccine Ag85A-ESAT-6-IL-21 priming and BCG boosting.

Abstract: Tuberculosis (TB) is one of most important chronic infectious diseases caused by Mycobacterium tuberculosis and remains a major global health problem. In the study, we developed the DNA vaccine encoding fusion protein of antigen 85 A and 6 kDa early secretory antigen target of M. tuberculosis as well as the cytokine IL-21 to investigate its immune protective efficacy against M. tuberculosis challenge in mice after the DNA vaccine priming and Bacille Calmette-Guerin (BCG) boosting. Compared with the different control groups, the intranasal DNA vaccine priming twice and BCG boosting once markedly increased the cytotoxicities of natural killer cells and splenocytes and enhanced the interferon-γ level in the splenocyte supernatant as well as sIgA level in bronchoalveolar lavage in the vaccinated mice. Importantly, this heterologous prime-boost strategy significantly decreased the bacterial load in the mouse lungs in contrast to that of intranasal or subcutaneous BCG immunization alone. These findings provide further approaches for mucosal-targeted prime-boost vaccination to fight against TB.

Enhanced piezoelectric and antiferroelectric properties of high-TC perovskite of Zr-substituted Bi(Mg1/2Ti1/2)O3-PbTiO3

Abstract: Bi(Mg1/2Ti1/2)O3-PbTiO3 is a promising high-TC piezoelectrics in the Bi-based perovskite family of BiMeO3-PbTiO3. In this study, zirconium is utilized to further improve the high temperature piezoelectric properties of Bi(Mg1/2Ti1/2)O3-PbTiO3. Substitution of Zr for Ti is observed to decrease the tetragonality (c/a) near the morphotropic phase boundary, while TC can be well maintained by the substitution of smaller and ferroelectrically active Ti by a larger and ferroelectrically weaker Zr cation. A softer coercive field and enhanced domain mobility is observed, ultimately leading to a strong ferroelectric activity. The piezoelectric property of Zr-substituted Bi(Mg1/2Ti1/2)O3-PbTiO3 is enhanced to 260 pC/N, when compared with Bi(Mg1/2Ti1/2)O3-PbTiO3 (225 pC/N). Good high temperature piezoelectric property was found in the tetragonal phase of Zr-substituted Bi(Mg1/2Ti1/2)O3-PbTiO3. Thermal depoling of aligned domains for this composition occurs at approximately 300 °C. Thus, Zr-substituted Bi(Mg1/2Ti1/2)O3-PbTiO3 could be used for high temperature actuator applications. Furthermore, an apparent ferroelectric-antiferroelectric phase transition was observed as a function of both the composition in the rhombohedral phase and the temperature. An antiferroelectric relaxor exists in the Zr-substituted Bi(Mg1/2Ti1/2)O3-PbTiO3.

Differential expression of phospholipase C epsilon 1 is associated with chronic atrophic gastritis and gastric cancer.

Abstract: Background Chronic inflammation plays a causal role in gastric tumor initiation. The identification of predictive biomarkers from gastric inflammation to tumorigenesis will help us to distinguish gastric cancer from atrophic gastritis and establish the diagnosis of early-stage gastric cancer. Phospholipase C epsilon 1 (PLCe1) is reported to play a vital role in inflammation and tumorigenesis. This study was aimed to investigate the clinical significance of PLCe1 in the initiation and progression of gastric cancer. Methodology/Principal Findings Firstly, the mRNA and protein expression of PLCe1 were analyzed by reverse transcription-PCR and Western blotting in normal gastric mucous epithelial cell line GES-1 and gastric cancer cell lines AGS, SGC7901, and MGC803. The results showed both mRNA and protein levels of PLCe1 were up-regulated in gastric cancer cells compared with normal gastric mucous epithelial cells. Secondly, this result was confirmed by immunohistochemical detection in a tissue microarray including 74 paired gastric cancer and adjacent normal tissues. Thirdly, an independence immunohistochemical analysis of 799 chronic atrophic gastritis tissue specimens demonstrated that PLCe1 expression in atrophic gastritis tissues were down-regulated since PLCe1 expression was negative in 524 (65.6%) atrophic gastritis. In addition, matched clinical tissues from atrophic severe gastritis and gastric cancer patients were used to further confirm the previous results by analyzing mRNA and protein levels expression of PLCe1 in clinical samples. Conclusions/Significances Our results suggested that PLCe1 protein may be a potential biomarker to distinguish gastric cancer from inflammation lesion, and could have great potential in applications such as diagnosis and pre-warning of early-stage gastric cancer.

Ab initio many-body study of the electronic and optical properties of MgAl2O4 spinel

Abstract: The electronic structure and optical properties of MgAl2O4 spinel with and without oxygen vacancies have been studied in the framework of many-body perturbation theory. By considering the self-energy of electrons, we reasonably describe the bandgap of perfect MgAl2O4 and the defect energy levels of MgAl2O4 containing oxygen vacancies. With the inclusion of electron-hole interaction by solving Bethe-Salpeter equation, the calculated dielectric functions and reflectivity spectrum all are in agreement well with the experimental results for perfect MgAl2O4. Our results show that the sharp peak near 7.8 eV in the experimental absorption spectrum is attributed to the excitonic states. The oxygen vacancies produce some new defect energy levels in the forbidden gap. The optical absorption peaks at 5.3 eV, 4.75 eV and 3.2 eV are induced by the V-O(0) and V-O(1+) vacancies. (C) 2012 American Institute of Physics. [doi:10.1063/1.3686727]