Interface Optimization and Transport Modulation of Sm2O3/InP Metal Oxide Semiconductor Capacitors with Atomic Layer Deposition-Derived Laminated Interlayer.

In this paper, the effect of atomic layer deposition-derived laminated interlayer on the interface chemistry and transport characteristics of sputtering-deposited Sm2O3/InP gate stacks have been investigated systematically. Based on X-ray photoelectron spectroscopy (XPS) measurements, it can be noted that ALD-derived Al2O3 interface passivation layer significantly prevents the appearance of substrate diffusion oxides and substantially optimizes gate dielectric performance. The leakage current experimental results confirm that the Sm2O3/Al2O3/InP stacked gate dielectric structure exhibits a lower leakage current density than the other samples, reaching a value of 2.87 × 10-6 A/cm2. In addition, conductivity analysis shows that high-quality metal oxide semiconductor capacitors based on Sm2O3/Al2O3/InP gate stacks have the lowest interfacial density of states (Dit) value of 1.05 × 1013 cm-2 eV-1. The conduction mechanisms of the InP-based MOS capacitors at low temperatures are not yet known, and to further explore the electron transport in InP-based MOS capacitors with different stacked gate dielectric structures, we placed samples for leakage current measurements at low varying temperatures (77-227 K). Based on the measurement results, Sm2O3/Al2O3/InP stacked gate dielectric is a promising candidate for InP-based metal oxide semiconductor field-effect-transistor devices (MOSFET) in the future.

Recent progress in sensing application of metal nanoarchitecture-enhanced fluorescence.

Fluorescence analytical methods, as real time and in situ analytical approaches to target analytes, can offer advantages of high sensitivity/selectivity, great versatility, non-invasive measurement and easy transmission over long distances. However, the conventional fluorescence assay still suffers from low specificity, insufficient sensitivity, poor reliability and false-positive responses. By exploiting various metal nanoarchitectures to manipulate fluorescence, both increased fluorescence quantum yield and improved photostability can be realized. This metal nanoarchitecture-enhanced fluorescence (MEF) phenomenon has been extensively studied and used in various sensors over the past years, which greatly improved their sensing performance. Thus in this review, we primarily give a general overview of MEF based sensors from mechanisms to state-of-the-art applications in environmental assays, biological/medical analysis and diagnosis areas. Finally, their pros and cons as well as further development directions are also discussed.

Homocysteine, interleukin-1ß, and fasting blood glucose levels as prognostic markers for diabetes mellitus complicated with cerebral infarction and correlated with carotid intima-media thickness.

Diabetes mellitus complicated with cerebral infarction (DMCI) has a high incidence and disability rate. Therefore, identification of biomarkers for the early prediction of the development and progression of cerebral infarction (CI) is of great significance for the prevention and treatment of this disease. The roles of serum homocysteine (Hey), interleukin-1ß (IL-1ß), and fasting blood glucose (FBG) in DMCI and their correlations with carotid intima-media thickness (CIMT) were explored. A total of 124 patients with DMCI (DMCI group) and 103 patients with diabetes mellitus (DM) (DM group) admitted to the People's Hospital of Liuhe District of Nanjing were enrolled in this study. A further 100 healthy controls undergoing physical examinations during the same period (HC group) were also enrolled. CIMT value was detected by carotid artery ultrasound. Hey and FBG levels were determined by a fully automatic biochemical analyzer. The IL-1ß level was detected by enzyme-linked immunosorbent assay (ELISA). The levels of Hey, IL-1ß, and FBG and the CIMT value in the DMCI and DM groups were significantly higher than those in the HC group (P<0.001). The levels and the value in the DMCI group were significantly higher than those in the DM group (P<0.001). Hey, IL-1ß, and FBG levels were positively correlated with CIMT value (r=0.542, P<0.001; r=0.522, P<0.001; r=0.402, P<0.001). Receiver operating characteristic (ROC) curves showed that the sensitivity and specificity of Hey for diagnosing DMCI were 86.29 and 80.58%; those of IL-1ß were 68.55 and 86.41%; those of FBG were 69.35 and 88.35%. Multivariate logistic regression analysis revealed that systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), Hey, IL-1ß, FBG, and CIMT were independent risk factors for DMCI (P<0.05). In conclusion, patients with DMCI have severe atherosclerosis. Hey, IL-1ß, and FBG are involved in the development and progression of DMCI, so they can be used as predictive markers for the disease. Hey, IL-1ß, FBG, and CIMT are independent risk factors for patients with DMCI.

Superior visible light photocatalytic performance of reticular BiVO4 synthesized via a modified sol-gel method.

Reticular BiVO4 catalysts were successfully synthesized via a modified sol-gel method. Here, citric acid (CA) was used as the chelating agent and ethylenediaminetetraacetic acid (EDTA) was used as the chelating agent and template. Furthermore, the effects of pH values and EDTA on the structure and morphology of the samples were studied. We determined that EDTA and pH played important roles in the determination of the morphology of the as-prepared BiVO4 samples. Photocatalytic evaluation revealed that the reticular BiVO4 exhibited superior photocatalytic performance characteristics for the degradation of methylene blue (MB) under visible-light (λ > 400 nm) exposure, about 98% of the MB was found to degrade within 50 min. Moreover, the degradation kinetics of MB was in good agreement with pseudo-first-order kinetics. The obtained apparent reaction rate constant k app of reticular BiVO4 was much higher than that of BiVO4 synthesized by the citric acid sol-gel method.

Simple and seamless broadband optical frequency comb generation using an InAs/InP quantum dot laser.

A simple and seamless broadband optical frequency comb (OFC) generator is proposed and experimentally demonstrated using a Fabry-Perot quantum dot mode-locked laser combined with a dual-driven LiNbO3 Mach-Zehnder modulator driven by a low-power radio frequency (RF) signal. It is experimentally demonstrated that the 10-dB seamless bandwidth of the OFC is 8.2 nm (1.02 THz), which has 62 and 40 comb lines for frequency intervals of 16.56 GHz and 24.84 GHz, respectively. The single-sideband phase noise is as low as -112 and -108 dBc/Hz at an offset of 10 kHz, respectively, for the photodetector-converted 16.56 and 24.84 GHz frequency carriers. Correspondingly, the RF linewidths of the 16.56 GHz and 24.84 GHz carriers are about 251 Hz-263 Hz, respectively. Using a QD laser, an ultra-low phase noise and quasi-tunable broadband OFC generator is obtained easily.

The effects of surface spin on magnetic properties of weak magnetic ZnLa0.02Fe1.98O4 nanoparticles.

In order to prominently investigate the effects of the surface spin on the magnetic properties, the weak magnetic ZnLa0.02Fe1.98O4 nanoparticles were chosen as studying objects which benefit to reduce as possibly the effects of interparticle dipolar interaction and crystalline anisotropy energies. By annealing the undiluted and diluted ZnLa0.02Fe1.98O4 nanoparticles at different temperatures, we observed the rich variations of magnetic ordering states (superparamagnetism, weak ferromagnetism, and paramagnetism). The magnetic properties can be well understood by considering the effects of the surface spin of the magnetic nanoparticles. Our results indicate that in the nano-sized magnets with weak magnetism, the surface spin plays a crucial rule in the magnetic properties.

Carbenoxolone pretreatment and treatment of posttraumatic epilepsy.

Gap junction blocking agents can inhibit spontaneous discharge frequency in cells. We established a rat model of posttraumatic epilepsy induced using ferric ions. Rats were intraperitoneally injected with carbenoxolone, 20 mg/kg, prior to and 30 minutes after model establishment, once a day for 14 consecutive days. Immunohistochemistry showed glial cell proliferation around a cortical focus and significantly increased connexin expression in posttraumatic epilepsy. However, carbenoxolone pretreatment or treatment significantly reduced connexin expression in the cortex, inhibited glial fibrillary acidic protein expression and ameliorated seizure degree in rats. These findings indicate that large amounts of glial cell proliferation and abnormal gap junction generation play a role in posttraumatic epilepsy, and that carbenoxolone may prevent and treat this disease.

C-doped ZnO nanowires: electronic structures, magnetic properties, and a possible spintronic device.

Electronic structures, magnetic properties, and spin-dependent electron transport characteristics of C-doped ZnO nanowires have been investigated via first-principles method based on density functional theory and nonequilibrium techniques of Green's functions. Our calculations show that the doping of carbon atoms in a ZnO nanowire could induce strong magnetic moments in the wire, and the electronic structures as well as the magnetic properties of the system sensitively depend on partial hydrogenation. Based on these findings, we proposed a quasi-1d tunneling magnetic junction made of a partially hydrogenated C-doped ZnO nanowire, which shows a high tunneling magnetoresistance ratio, and could be the building block of a new class of spintronic devices.

Energy-gap opening and quenching in graphene under periodic external potentials.

We investigated the effects of periodic external potentials on properties of charge carriers in graphene using both the first-principles method based on density functional theory (DFT) and a theoretical approach based on a generalized effective spinor Hamiltonian. DFT calculations were done in a modified Kohn-Sham procedure that includes the effects of the periodic external potential. Unexpected energy band gap opening and quenching were predicted for the graphene superlattice with two symmetrical sublattices and those with two unsymmetrical sublattices, respectively. Theoretical analysis based on the spinor Hamiltonian showed that the correlations between pseudospins of Dirac fermions in graphene and the applied external potential, and the potential-induced intervalley scattering, play important roles in energy-gap opening and quenching.

Greatly enhanced adsorption and catalytic activity of Au and Pt clusters on defective graphene.

We report an investigation on CO oxidation catalyzed by Au(8) or Pt(4) clusters on defective graphene using first-principles approach based on density functional theory. The simplest single-carbon-vacancy defect on graphene was found to play an essential role in the catalyzed chemical reaction of CO oxidation. When supported on a defect-free graphene sheet, the reaction barrier of CO oxidation catalyzed by Au(8) (Pt(4)) clusters was estimated to be around 3.0 eV (0.5 eV), and when adsorbed on defective graphene, the reaction barrier was greatly reduced to around 0.2 eV (0.13 eV).

The size effects of electrodes in molecular devices: an ab initio study on the transport properties of C(60).

The role of electrodes in the transport properties of molecular devices is investigated by taking C(60) as an example and using gold nanowire and a gold atomic chain as the electrodes. The calculations are done by an ab initio method combined with the non-equilibrium Green function technique. We find that devices in which a single C(60) molecule is connected with different electrodes show completely different transport behavior. In the case of nanowire/C(60)/nanowire the device shows a metallic behavior with a big equilibrium conductance (about 2.18G(0)) and the current increases rapidly and almost linearly starting from zero. The transmission function shows wide peaks and platforms around the Fermi level. While in the atomic-chain/C(60)/atomic-chain case, the device shows resonant tunneling behavior and the Fermi level lies between the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) transmission peaks. This results in a current that is one order of magnitude smaller than that in the nanowire/C(60)/nanowire system and the current increases very slowly until the bias is big enough to include the LUMO peak in the bias window. The big difference in the conductance and the current arises from the different coupling between the electrodes and the C(60) and the different number of channels in the electrodes.

Changes of coupling between the electrodes and the molecule under external bias bring negative differential resistance.

We report a first-principles study of electrical transport and negative differential resistance (NDR) in a single molecular conductor consisting of a borazine ring sandwiched between two Au(100) electrodes with a finite cross section. The projected density of states (PDOS) and transmission coefficients under various external voltage biases are analyzed, and it suggests that the variation of the coupling between the molecule and the electrodes with external bias leads to NDR. Therefore, we propose that one origin of NDR in molecular devices is caused by the characteristics of both the molecule and the electrodes as well as their cooperation, not necessarily only by the inherent properties of certain species of molecules themselves. The changes of charge state of the molecule have minor effects on NDR in this device because the Mulliken population analysis shows that electron occupation variation on the molecule is very small when different external biases are applied.