[Efficacy and safety of body-insulated acupuncture needle for electrical stimulation at rabbit scia-tic nerve trunk].

OBJECTIVE: To evaluate the efficacy and safety of electrical stimulation at the rabbit sciatic nerve trunk with the body-insulated acupuncture needle whose body is painted with insulating material. METHODS: Eighteen male New Zealand rabbits were randomized into the body-insulated acupuncture needle (BIAN), the general acupuncture needle (GAN), and the blank control groups，with 6 rabbits in each group. The rats'sciatic nerve trunks in BIAN and GAN groups were stimulated by electroacupuncture with the body-insulated acupuncture needle (only allowing the uncoated needle handle and tip to conduct electricity) and the general acupuncture needle, separately. The current intensity was recorded when regular plantarflexion reflexes (sciatic nerve effector reflexes) were observed in the rabbit's foot. The pathological changes of the sciatic nerve at the acupuncture site were observed by H.E. staining, and the ultrastructural changes of the sciatic nerve trunk were observed by transmission electron microscope. RESULTS: The intensity of the current causing the regular plantar flexion reflection in BIAN group (ï¼»0.29±0.07ï¼½ mA) was significantly lower than that in the GAN group(ï¼»0.86±0.08ï¼½ mA, P<0.01). H.E. staining revealed nerve axon degeneration, forming eosinophilic bodies, nerve fiber edema, and focal loss of myelin sheath in the GAN group. While the nerve fiber damage was not obvious, and axons were only degenerated in a few areas in the BIAN group. Transmission electron microscopy observations showed that the nerve myelin sheath structure was separated, the layers were arranged disorderly and bubbled in the GAN group. while the nerve myelin sheath structure of the BIAN group was normal, and it presents a concentric circle-like light and dark lamellar structure, with fewer myelin vacuoles and fissures, only a small part of the mitochondria, microfilaments, and microtubules of the nerve axons were abnormal, and the overall vacuole-like degeneration was significantly reduced, with few of the myelinated fibers were slightly degenerated, and axonal disease was not obvious. CONCLUSION: Insulated acupuncture needle is more accurate and safer than ordinary acupuncture needle for electrical stimulation of rabbit sciatic nerve trunk, and the required electric current intensity is smaller.

Nanoscale imaging of the photoresponse in PN junctions of InGaAs infrared detector.

Electronic layout, such as distributions of charge carriers and electric field, in PN junction is determinant for the photovoltaic devices to realize their functionality. Considerable efforts have been dedicated to the carrier profiling of this specific region with Scanning Probe Microscope, yet reliable analysis was impeded by the difficulty in resolving carriers with high mobility and the unclear surface effect, particularly on compound semiconductors. Here we realize nanometer Scanning Capacitance Microscopic study on the cross-section of InGaAs/InP photodetectors with the featured dC/dV layout of PN junction unveiled for the first time. It enables us to probe the photo-excited minority carriers in junction region and diagnose the performance deficiency of the diode devices. This work provides an illuminating insight into the PN junction for assessing its basic capability of harvesting photo-carriers as well as blocking leakage current in nanoscopic scale.

Self-induced uniaxial strain in MoS2 monolayers with local van der Waals-stacked interlayer interactions.

Strain engineering is an effective method to tune the properties of electrons and phonons in semiconductor materials, including two-dimensional (2D) layered materials (e.g., MoS2 or graphene). External artificial stress (ExAS) or heterostructure stacking is generally required to induce strains for modulating semiconductor bandgaps and optoelectronic functions. For layered materials, the van der Waals-stacked interlayer interaction (vdW-SI) has been considered to dominate the interlayer stacking and intralayer bonding. Here, we demonstrate self-induced uniaxial strain in the MoS2 monolayer without the assistance of ExAS or heterostructure stacking processes. The uniaxial strain occurring in local monolayer regions is manifested by the Raman split of the in-plane vibration modes E2g(1) and is essentially caused by local vdW-SI within the single layer MoS2 due to a unique symmetric bilayer stacking. The local stacked configuration and the self-induced uniaxial strain may provide improved understanding of the fundamental interlayer interactions and alternative routes for strain engineering of layered structures.

[Maize Hybrid Seed Purity Identification Based on Near Infrared Reflectance (NIR) and Transmittance (NIT) Spectra].

This article explore the feasibility of using Near Infrared Reflectance (NIR) and Transmittance (NIT) Spectroscopy (908.1-1677.2 nm wavelength range) to identify maize hybrid purity, and compare the performance of NIR and NIT spectroscopy. Principle Component Analysis (PCA) and Orthogonal Linear Discriminant Analysis (OLDA) were used to reduce the dimension of spectra which have been pretreated by first derivative and vector normalization. The hybrid purity identification model of Nonghua101 and Jingyu16 were built by SVM. Models based on NIR spectra obtained correct identification rate as 100% and 90% for Nonghua101 and Jingyu16 respectively. But NIR spectra were greatly influenced by the placement of seeds, and there existed significant difference between NIR spectra of embryo and non-embryo side. Models based on NIT spectroscopy yielded correct identification rate as 98% both for Nonghua101 and Jingyu16. NIT spectra of embryo and non-embryo side were highly similar. The results indicate that it is feasible to identify maize hybrid purity based on NIR and NIT spectroscopy, and NIT spectroscopy is more suitable to analyze single seed kernel than NIR spectroscopy.

[Source and health risk assessment of heavy metals in ambient air PM10 from one coking plant].

To investigate the sources and health risk of heavy metals in ambient air PM10 from the coking plant, the PM10 in the air around one coking plant was collected in June 2012. Then the heavy metals concentrations in PM10 were tested by the microwave-ICP-MS method. Furthermore, the USEPA's human exposure assessment model was applied to preliminarily evaluate the human health risks of the heavy metals in air particulate matter. The results show that the concentrations of 10 kinds of heavy metals in PM10 from the coking plant vary significantly, ranging from 3.06 x 10(-5) mg x m(-3) to 1.77 x 10(-2) mg x m(-3), of which the concentration of Cr is the highest, while the concentration of Co is the lowest, and the concentration of the carcinogenic substances is higher than that of the non-carcinogenic substances. The coking plant is identified to be the major source of the heavy metals in ambient air PM10, and Ni is the main polluting heavy metal. Moreover, the heavy risk assessment results reveal that the carcinogenic risks for adults are higher than children, while the carcinogenic risks in industrial areas and school relatively large. The non-carcinogenic risks for children are the highest in all the population, and the non-carcinogenic risks in residential area can not be ignored. Among the carcinogenic substances, the potential carcinogenic risks of Cd, Cr and As are comparatively large, Ni and Co have certain potential risks. Whereas, among the non-carcinogenic substances, the non-carcinogenic risks of Mn is great. Consequently, relevant departments should pay close attention to this situation.

Single InAs nanowire room-temperature near-infrared photodetectors.

Here we report InAs nanowire (NW) near-infrared photodetectors having a detection wavelength up to ∼1.5 µm. The single InAs NW photodetectors displayed minimum hysteresis with a high Ion/Ioff ratio of 10(5). At room temperature, the Schottky-Ohmic contacted photodetectors had an external photoresponsivity of ∼5.3 × 10(3) AW(-1), which is ∼300% larger than that of Ohmic-Ohmic contacted detectors (∼1.9 × 10(3) AW(-1)). A large enhancement in photoresponsivity (∼300%) had also been achieved in metal Au-cluster-decorated InAs NW photodetectors due to the formation of Schottky junctions at the InAs/Au cluster contacts. The photocurrent decreased when the photodetectors were exposed to ambient atmosphere because of the high surface electron concentration and rich surface defect states in InAs NWs. A theoretical model based on charge transfer and energy band change is proposed to explain this observed performance. To suppress the negative effects of surface defect states and atmospheric molecules, new InAs NW photodetectors with a half-wrapped top-gate had been fabricated by using 10 nm HfO2 as the top-gate dielectric.

Distinct photocurrent response of individual GaAs nanowires induced by n-type doping.

The doping-dependent photoconductive properties of individual GaAs nanowires have been studied by conductive atomic force microscopy. Linear responsivity against the bias voltage is observed for moderate n-doped GaAs wires with a Schottky contact under illumination, while that of the undoped ones exhibits a saturated response. The carrier lifetime of a single nanowire can be obtained by simulating the characteristic photoelectric behavior. Consistent with the photoluminescence results, the significant drop of minority hole lifetime, from several hundred to subpicoseconds induced by n-type doping, leads to the distinct photoconductive features. Moreover, by comparing with the photoelectric behavior of AlGaAs shelled nanowires, the equivalent recombination rate of carriers at the surface is assessed to be >1 × 10(12) s(-1) for 2 × 10(17)cm(-3) n-doped bare nanowires, nearly 30 times higher than that of the doping-related bulk effects. This work suggests that intentional doping in nanowires could change the charge status of the surface states and impose significant impact on the electrical and photoelectrical performances of semiconductor nanostructures.