Ammonia Electrosynthesis with a Stable Metal-Free 2D Silicon Phosphide Catalyst.

Metal-free 2D phosphorus-based materials are emerging catalysts for ammonia (NH3 ) production through a sustainable electrochemical nitrogen reduction reaction route under ambient conditions. However, their efficiency and stability remain challenging due to the surface oxidization. Herein, a stable phosphorus-based electrocatalyst, silicon phosphide (SiP), is explored. Density functional theory calculations certify that the N2 activation can be realized on the zigzag Si sites with a dimeric end-on coordinated mode. Such sites also allow the subsequent protonation process via the alternating associative mechanism. As the proof-of-concept demonstration, both the crystalline and amorphous SiP nanosheets (denoted as C-SiP NSs and A-SiP NSs, respectively) are obtained through ultrasonic exfoliation processes, but only the crystalline one enables effective and stable electrocatalytic nitrogen reduction reaction, in terms of an NH3 yield rate of 16.12 µg h-1  mgcat. -1 and a Faradaic efficiency of 22.48% at -0.3 V versus reversible hydrogen electrode. The resistance to oxidization plays the decisive role in guaranteeing the NH3 electrosynthesis activity for C-SiP NSs. This surface stability endows C-SiP NSs with the capability to serve as appealing electrocatalysts for nitrogen reduction reactions and other promising applications.

A Multi-Mode Switching Variational Bayesian Adaptive Kalman Filter Algorithm for the SINS/PNS/GMNS Navigation System of Pelagic Ships.

The ocean-going environment is complex and changeable with great uncertainty, which poses a huge challenge to the navigation ability of ships working in the pelagic ocean. In this paper, in an attempt to deal with the complex uncertain interference that the environment may bring to the strap-down inertial navigation system/polarization navigation system/geomagnetic navigation system (SINS/PNS/GMNS) integrated navigation system, the multi-mode switching variational Bayesian adaptive Kalman filter (MMS-VBAKF) algorithm is proposed. To be more specific, to identify the degrees of measurement interference more effectively, we design an interference evaluation and multi-mode switching mechanism using the original polarization information and geomagnetic information. Through this mechanism, the interference to the SINS/PNS/GMNS navigation system is divided into three cases. In case of slight interference (case SI), the variational Bayesian method is adopted directly to solve the problem that the statistical characteristics of measurement noise are unknown. By the fixed-point iteration mechanism, the statistical properties of the measurement noise and the system states can be estimated adaptively in real time. In case of interference-tolerance (case TI), the estimation of the statistical characteristics of measurement noise need to weigh the measurement information at the moment and a priori value information comprehensively. In case of excessive interference (case EI), the SINS/PNS/GMNS integrated navigation system will perform mode switching and filtering system reconstruction in advance. Then, the information fusion and navigation states estimation can be completed. Consequently, the reliability, robustness, and accuracy of the SINS/PNS/GMNS integrated navigation system can be guaranteed. Finally, the effectiveness of the algorithm is illustrated by the simulation experiments.

Bionic Integrated Positioning Mechanism Based on Bioinspired Polarization Compass and Inertial Navigation System.

In this paper, to address the problem of positioning accumulative errors of the inertial navigation system (INS), a bionic autonomous positioning mechanism integrating INS with a bioinspired polarization compass is proposed. In addition, the bioinspired positioning system hardware and the integration model are also presented. Concerned with the technical issue of the accuracy and environmental adaptability of the integrated positioning system, the sun elevation calculating method based on the degree of polarization (DoP) and direction of polarization (E-vector) is presented. Moreover, to compensate for the latitude and longitude errors of INS, the bioinspired positioning system model combining the polarization compass and INS is established. Finally, the positioning performance of the proposed bioinspired positioning system model was validated via outdoor experiments. The results indicate that the proposed system can compensate for the position errors of INS with satisfactory performance.

Unravelling the effect of sulfur vacancies on the electronic structure of the MoS2 crystal.

Molybdenum disulfide (MoS2) is one of the two-dimensional layered semiconductor transition metal dichalcogenides (TMDCs) with great potential in electronics, optoelectronics, and spintronic devices. Sulfur vacancies in MoS2 are the most prevalent defects. However, the effect of sulfur vacancies on the electronic structure of MoS2 is still in dispute. Here we experimentally and theoretically investigated the effect of sulfur vacancies in MoS2. The vacancies were intentionally introduced by thermal annealing of MoS2 crystals in a vacuum environment. Angle-resolved photoemission spectroscopy (ARPES) was used directly to observe the electronic structure of the MoS2 single crystals. The experimental result distinctly revealed the appearance of an occupied defect state just above the valence band maximum (VBM) and an upward shift of the VBM after creating sulfur vacancies. In addition, density functional theory (DFT) calculations also confirmed the existence of the occupied defect state close to the VBM as well as two deep unoccupied states induced by the sulfur vacancies. Our results provide evidence to contradict that sulfur vacancies indicate the origin of n-type behaviour in MoS2. This work provides a rational strategy for tuning the electronic structures of MoS2.

Picosecond mid-infrared optical parametric amplifier based on LiInSe2 with tenability extending from 3.6 to 4.8 µm.

A picosecond (ps) mid-infrared (MIR) optical parametric amplifier (OPA) with LiInSe2 crystal was demonstrated for the first time. The MIR OPA was pumped by a 30 ps 1064 nm Nd:YAG laser and injected by a barium boron oxide (BBO)-based widely tunable near-infrared seed. A maximum idler pulse energy of 433 µJ at 4 µm has been obtained under a pump energy of 17 mJ, and the corresponding pulse duration was estimated to be ~13 ps. To our knowledge, this is the highest single pulse energy generated by LiInSe2 crystal. Furthermore, an idler spectrum tuning from 3.6 to 4.8 µm was investigated at fixed pump energy of 15 mJ.

Tunable 7-12 µm picosecond optical parametric amplifier based on a LiInSe2 mid-infrared crystal.

Mid-infrared (MIR) nonlinear optical crystals of LiInSe2 (LISe) were grown by a modified Bridgman technique on a (001)-seed. A 7-12 µm widely tunable picosecond (ps) MIR optical parametric amplifier (OPA) based on a LISe crystal was demonstrated for the first time, to the best of our knowledge. The MIR OPA was pumped by a 30 ps 1064 nm Nd:YAG laser and injected by a KTiOPO4 (KTP)-based widely tunable near-infrared seed. The idler operating at 7.5 µm with the highest pulse energy of 170 µJ was obtained under a pump energy of 14 mJ. The corresponding energy conversion efficiency is ∼1.21%, and the photon conversion efficiency is 8.6%. The output energies were measured to be ∼121 µJ at 7 µm and ∼21 µJ at 12 µm.

Intrinsic defects and their effects on the optical properties in the nonlinear optical crystal CdSiP2: a first-principles study.

In view of their high nonlinear optical coefficients and good phase-matching properties, CdSiP2 (CSP) crystals are considered as one of the most promising materials in the field of nonlinear optical applications. However, the slight absorption losses around 1.34 µm and 1.78 µm under e-polarized light have been affecting its performance. In this study, first-principles calculations were performed to identify the effects of various charge defects on the absorption properties. Different intrinsic defects in the CSP crystal were calculated using the HSE method and compared according to the specific chemical environments in the experiments. The results show that the point defects of V, Si, and V, which can be spontaneously formed, are dominant in the Cd-poor environment. The combination of Si and V defects is the most favorable cluster in the Cd-poor case because of its relatively low formation energy. Furthermore, the antisite defect SiCd was found to be responsible for the main absorption peaks at 1.34 and 1.78 µm in the experimental spectra, whereas other defects and clusters, such as the defects Si and V, also contribute to these red shifted absorptions. Our results intend to provide a guideline for adjusting the optical absorption in CSP by modifying its defects.

Vibration Emissions Reduce Boar Sperm Quality via Disrupting Its Metabolism.

Artificial insemination (AI) with liquid-preserved semen has recently become common in pig breeding. The semen doses are produced in a centralized manner at the boar stud and then subsequently distributed and transported to sow farms. However, vibration emissions during transportation by logistic vehicles may adversely affect the quality of boar sperm. Therefore, this study aimed to explore the impact of vibration-induced emissions on sperm quality and function under simulated transportation conditions. Each time, ejaculates from all 15 boars were collected and then pooled together to minimize individual variations, and the sample was split using an extender for dilution. Different rotational speeds (0 rpm, 80 rpm, 140 rpm, 200 rpm) were utilized to simulate varying intensities of vibration exposure using an orbital shaker, considering different transportation times (0 h, 3 h, and 6 h). Subsequently, evaluations were conducted regarding sperm motility, plasma membrane integrity, acrosome integrity, mitochondrial function, adenosine triphosphate (ATP) levels, mitochondrial reactive oxygen species (ROS) levels, pH, glycolytic pathway enzyme activities, and capacitation following exposure to vibration emissions. Both vibration time and intensity impact sperm motility, plasma membrane integrity, and acrosomal integrity. Vibration exposure significantly reduced sperm ATP levels, mitochondrial membrane potential, and the levels of mitochondria-encoded proteins (MT-ND1, MT-ND6) (p < 0.05). After vibration emission treatment, the pH value and mitochondrial ROS levels significantly increased (p < 0.05). Inhibition of sperm glycolysis was observed, with reduced activities of hexokinase (HK), pyruvate kinase (PK), and lactate dehydrogenase (LDH), along with decreased lactate levels (p < 0.05). Additionally, sperm tyrosine phosphorylation levels were significantly reduced by vibration emissions compared to the control group (p < 0.05). After the vibration emission treatment, the number of sperm bound to each square millimeter of oviduct explants decreased significantly compared to the control group (p < 0.05). Similarly, compared to the control group, using semen subjected to vibration stress for AI results in significantly reduced pregnancy rates, total born litter size, live-born litter size, and healthy born litter size (p < 0.05).

2D SiP2/h-BN for a Gate-Controlled Phototransistor with Ultrahigh Sensitivity.

Two-dimensional (2D) materials are extremely attractive for the construction of highly sensitive photodetectors due to their unique electronic and optical properties. However, developing 2D photodetectors with ultrahigh sensitivity for extremely low-light-level detection is still a challenge owing to the limitation of high dark current and low detectivity. Herein, a gate-controlled phototransistor based on 2D SiP2/hexagonal boron nitride (h-BN) was rationally designed and demonstrated ultrahigh sensitivity for the first time. With a back-gate device geometry, the SiP2/h-BN phototransistor exhibits an ultrahigh detectivity of 3.4 × 1013 Jones, which is one of the highest values among 2D material-based photodetectors. In addition, the phototransistor also shows a gate tunable responsivity of ≤43.5 A/W at a gate voltage of 30 V due to the photogating effect. The ultrahigh sensitivity of the SiP2-based phototransistor is attributed to the extremely low dark current suppressed by the phototransistor configuration and the improved photocurrent by using h-BN as a substrate to reduce charge scattering. This work provides a facile strategy for improving the detectivity of photodetectors and validates the great potential of 2D SiP2 phototransistors for ultrasensitive optoelectronic applications.

[The occupational and procreation health of immigrant female workers in electron factory].

OBJECTIVE: To explore the occupational and reproductive health problems of migrant female workers in electron factory. METHODS: A total number of 2000 female migrant workers were randomly sampled from three electronic factories for the study. All were investigated by questionnaire and data were input to EpiData 3.0 data base, SPSS17.0 statistical software and analyzed by Chi-square test. RESULTS: 1971 complete questionnaires were received, the recovery rate reached over 98.6%. The average age of interviewees is (21.1 ± 3.9) years. Junior employee between 16 and 18 years accounted for 19.04%. The average working age was (1.1 ± 2.2) years and about 90% were single including 0.11% of them were divorced. The main occupational hazards were: sodium hydroxide, sodium carbonate, formaldehyde, hydrochloric acid, stannic anhydride, benzene analogues, n-hexane methanol, glycol isopropanol, sulphuric acid, nitric oxide, noise, ultraviolet radiation, etc. Workplace monitoring indicated that benzene and noise levels and ultraviolet radiation were over the national OEL at fewer worksites. More than 50% female workers worked over 8 hours per day and 83% of them worked 22 days per month. The ergonomic problems: 63.86% of them worked with tedious repetitiveness and monotonous job task. About 42% of them need to be continuously with standing posture. As a consequence, there were 30% workers complain about LBP, 21% had experienced work injury; 15% ∼ 18% had some non-specific discomfort, such as insomnia, dysacusis, dizzy and headache. The incidence rate of reproductive system such as abnormal menstrual cycle (5.71%), dysmenorrhea (25.11%), congestion (8.91%), etc. The first four reproductive system disease were pelvic inflammation, adnexitis, cervical erosion, and vaginitis. There are significant differences between continuous and temporary standing work, and repeated and unrepeated job action in terms of dysmenorrheal and congestion related-discomfort(P < 0.05). CONCLUSION: There are many occupational hazards in electronic industry. And there is somewhat a serious occupational and reproductive health problems among female migrant workers, that seem to be a matter of great concern.

Low-Dimensional Hybrid Lead Iodide Perovskites Single Crystals via Bifunctional Amino Acid Cross-Linkage: Structural Diversity and Properties Controllability.

Three-dimensional perovskite AMX3 has great potential in photoelectric applications, but the poor stability is a major problem that restricts its practical application. The emergence of lower dimensional perovskite solves this problem. Here, we have synthesized a group of novel low-dimensional perovskites with diverse structures. Different amino acids were incorporated in the perovskite cage. The formulas of the compounds are (A')mPbIm+2 (A' = COOH(CH2)nNH2, n = 1, 3, 5, 7, 9). These families of materials demonstrate structure-related stability, tunable bandgap, and different photoluminescence. Single-crystal X-ray diffraction indicated that the five materials employ different structure types varying from edge-sharing structures to face- and corner-sharing Pb/I structures by adjusting the number of C atoms in organic cations, and the level of [PbI6]4- octahedral distortion was also identified. The film prepared using these materials with longer carbon chains (n = 5, 7, 9) showed better stability, and they did not decompose within one year at 75% RH, 40 °C. The bifunctional organic ions containing carboxyl groups as spacer cations will form additional hydrogen bonding between perovskite layers, resulting in higher stability of the material. The band gaps of these materials vary from 2.19 to 2.6 eV depending on the octahedral connection mode and [PbI6]4- octahedral distortion level, density functional theory calculations (DFT) are consistent with our experimental trends and suggest that the face-sharing structure has the maximum band gap due to its flatter electron band structure. Bright green fluorescence was observed in (COOH(CH2)7NH3)2PbI4 and (COOH(CH2)9NH3)2PbI4 when excited by 365 nm UV light. A thorough comprehension of the structure-property relationships is of great significance for further practical applications of perovskites.

Removal of chlorophenols in the aquatic environment by activation of peroxymonosulfate with nMnOx@Biochar hybrid composites: Performance and mechanism.

Functional nMnOx@RBC composites were synthesized via a simple co-precipitation method. The nanomaterials have efficient activity in activating peroxymonosulfate (PMS) for removal of chlorophenols (CPs). Rice husk biochar (RBC) could support nMnOx, and acted as an electron shuttle to mediate electron transfer reaction. nMnOx@RBC had superior catalytic and adsorption properties and exhibited remarkable synergistic effects. This led to complete degradation of 4-chloro-3-methyl phenol (CMP) in 60 min at the natural pH (7.0). Reactive oxygen species (ROS) were also identified via the corresponding scavengers. The results indicated that singlet oxygen (1O2) played a dominant role in the degradation of CMP within nMnOx@RBC system. Moreover, the mechanism of CMP decomposition was rationally proposed, and possible intermediate products were deduced. The high degradation performances of diverse CPs were also observed in nMnOx@RBC/PMS system. This research aims to offer novel insights into carbon-metal nanomaterials for the elimination of emerging pollutants.

Strong In-Plane Anisotropic SiP2 as a IV-V 2D Semiconductor for Polarized Photodetection.

In-plane anisotropic two-dimensional (2D) materials, emerging as an intriguing type of 2D family, provide an ideal platform for designing and fabrication of optoelectronic devices. Exploring air-stable and strong in-plane anisotropic 2D materials is still challenging and promising for polarized photodetection. Herein, SiP2, a 2D IV-V semiconductor, is successfully prepared and introduced into an in-plane anisotropic 2D family. The basic characterizations combined with theoretical calculations reveal 2D SiP2 to exhibit an intrinsically low-symmetry structure, the in-plane anisotropy of phonon vibrations, and an anisotropically dispersed band structure. Moreover, the photodetector based on 2D SiP2 exhibits high performance with a high detectivity of 1012 Jones, a large light on/off ratio of 103, a low dark current of 10-13 A, and a fast response speed of 3 ms. Furthermore, 2D SiP2 demonstrates a high anisotropic photodetection with an anisotropic ratio up to 2. In addition, the polarization-sensitive photodetector presents a dichroic ratio of 1.6 due to the intrinsic linear dichroism. These good characteristics make 2D SiP2 a promising candidate as an in-plane anisotropic semiconductor for high-sensitivity and polarized optoelectronic applications.

Continuous-wave and passively Q-switched laser performance of LD-end-pumped 1062 nm Nd:GAGG laser.

Continuous-wave (CW) and passively Q-switched operations of LD-end-pumped Nd:Gd(3)Al(x)Ga(5-x)O(12) (Nd:GAGG) laser at 1062 nm were reported. The highest CW output power of 5.7 W was obtained, corresponding to an optical conversion efficiency and slope efficiency of 51.0% and 54.5%, respectively. The CW output efficiency of Nd:GAGG laser is comparable and even better than that of Nd:GGG. The passively Q-switched output was realized for the first time to our knowledge. In addition, a maximum output power of 1.12 W, a maximum pulse repetition rate of 39 kHz and a minimum pulse width of 6 ns were obtained by using Cr(4+):YAG as the saturable absorber.

Design and calibration model of a bioinspired attitude and heading reference system based on compound eye polarization compass.

Insects such as honeybees are capable of fusing the information sensed by multiple sensory organs for attitude and heading determination. In this paper, inspired by the sensory fusion mechanism of insects' polarization compass and haltere, a bioinspired polarization-based attitude and heading reference system (PAHRS) is presented. The PAHRS consists of compound eye polarization compass and inertial measurement unit (IMU). By simulating multi-view structure of the dorsal rim area in insects' compound eyes, a non-coplanar 'polarization-opponent (POL)-type' architecture is adopted for the compound eye polarization compass. The polarization compass has multi-directional observation channels, which is capable of adaptively selecting the angle of polarization and obtaining the polarization vectors. Therefore, the environmental adaptability of the polarization compass can be enhanced. In addition, the integration strategy between the compound eye polarization compass and IMU is proposed. Moreover, the sources of system errors are analyzed to improve the heading angle accuracy, based on which a new calibration model is established to compensate the installation errors of the PAHRS. Finally, experiments are carried out under both clear sky and cloudy conditions. The test results show that the error root mean square of heading angle is 0.14° in clear sky, and 0.42° in partly cloudy conditions.

Environmentally-friendly sonochemistry synthesis of hybrids from lignocelluloses and silver.

The purpose of this study was to explore a green strategy about the high value-added applications of biomass. Hybrids from lignocelluloses and silver have been successfully prepared using NaBH4 as reducing reagent by an environmentally-friendly sonochemistry method. The phase, microstructure, and morphology of the hybrids were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The influences of the various reaction parameters including reaction time, lignocelluloses concentration, and types of reducing reagents on the products were investigated in detail. Silver particles can be better dispersed on the lignocelluloses matrix by adjusting reaction parameters. These hybrids may be a promising antimicrobial material for their applications in the biomedical field. This environmentally-friendly synthetic strategy reported here opens a new window to the high value-added applications of lignocelluloses.

Temperature dependence of elastic properties and piezoelectric applications of BaTeMo2O9 single crystal.

BaTeMo(2)O(9) (BTM) single crystal, as a lead-free piezoelectric material, belongs to the monoclinic system, space group P2(1). We report the temperature dependence of the elastic constants by the transmission method over the range -50°C to 150°C. The first-order temperature coefficients of the elastic constant s(44) is about 180 × 10(-6)/°C. Piezoelectric resonators based on BTM crystal using the thickness-stretching vibration and the shear vibration modes were designed and evaluated, which eliminated or minimized the influence of the off-principal axis coefficients. The Q(m) of one of the resonators is about 600. Our results show that the elastic constants have good temperature stability, and the resonators have already met the requirements for some piezoelectric applications. This study on the BTM crystal has revealed the application for the low-symmetry crystal.