Thickness- and Field-Dependent Magnetic Domain Evolution in van der Waals Fe3GaTe2.

The discovery of room-temperature ferromagnetism in van der Waals (vdW) materials opens new avenues for exploring low-dimensional magnetism and its applications in spintronics. Recently, the observation of the room-temperature topological Hall effect in the vdW ferromagnet Fe3GaTe2 suggests the possible existence of room-temperature skyrmions, yet skyrmions have not been directly observed. In this study, real-space imaging was employed to investigate the domain evolution of the labyrinth and skyrmion structure. First, Néel-type skyrmions can be created at room temperature. In addition, the influence of flake thickness and external magnetic field (during field cooling) on both labyrinth domains and the skyrmion lattice is unveiled. Due to the competition between magnetic anisotropy and dipole interactions, the specimen thickness significantly influences the density of skyrmions. These findings demonstrate that Fe3GaTe2 can host room-temperature skyrmions of various sizes, opening up avenues for further study of magnetic topological textures at room temperature.

Enhancement of NO2 Gas Sensing Properties of Polypyrrole by Polarization Doping with DBS: Experimental and DFT Studies.

A new technique of polarization doping was adopted to improve NO2 gas sensing properties of the polypyrrole (PPy) sensor. PPy nanosheets polarization doped with sodium dodecyl benzenesulfonate (SDBS) were synthesized by low-temperature polymerization. The semiagglomerated PPy nanosheets were well-dispersed and a large specific surface areas due to the introduction of dodecyl benzenesulfonate (DBS). The DBS doped PPy sensor shows excellent NO2 sensing performance. Polarization of sulfonate ions to PPy enhanced the adsorption ability of NO2 with the synergistic effect of NO2. The adsorption energy (-0.676 eV) and electron transfer (0.521 |e|) of PPy to NO2 increased greatly after doping. An unoccupied electron state is observed in the valence band electron structure of PPy/DBS after the adsorption of NO2 by calculations of Density Functional Theory (DFT). The intermolecular synergy between NO2 and PPy/DBS causes a strong polarization, resulting in a high polarization potential, which enhances the NO2 sensing performance of PPy sensor. It is of great significance to develop NO2 detection device based on PPy that works at room temperature.

Penta-BeP2 Monolayer: A Superior Sensor for Detecting Toxic Gases in the Air with Excellent Sensitivity, Selectivity, and Reversibility.

Directly and quickly detecting toxic gases in the air is urgently needed in industrial production and our daily life. However, the poor gas selectivity and low sensitivity under ambient conditions limit the development of gas sensors. In this work, we demonstrate that the penta-BeP2 monolayer is an excellent toxic gas sensor by using first-principles calculations. The calculated results show that the semiconducting penta-BeP2 monolayer can chemisorb toxic gas molecules (including CO, NH3, NO, and NO2) with distinct charge transfer (-0.182 to 1.129 e) but negligibly interact with ambient gas molecules (including H2, N2, H2O, O2, and CO2), indicating high gas selectivity for primary environmental gases. The calculated I-V curves show that the penta-BeP2 monolayer exhibits a fast response with toxic gas molecules. Upon interaction with CO, NH3, NO, and NO2 molecules at a bias voltage of 0.7 V, the currents are 10.23, 14.48, 32.10, and 129.90 times that of the pristine penta-BeP2 monolayer, respectively, which induces high sensitivity values of 9.23, 13.48, 31.10, and 128.90, respectively. Moreover, the moderate adsorption energies of all toxic gas molecules guarantee that the penta-BeP2 monolayer possesses good reversibility at room temperature with a short recovery time. Herein, all of our results indicate that the penta-BeP2 monolayer could be a superior candidate for sensing toxic gases with high selectivity, sensitivity, and reversibility.

Novel Two-Dimensional ABX3 Dirac Materials: Achieving a High-Speed Strain Sensor via a Self-Doping Effect.

The pristine semimetal property of two-dimensional (2D) Dirac materials has limited their practical applications in today's electronic devices. Here we report a new type of 2D Dirac material, termed ABX3 (A = F, Cl, Br, or I; B = P or As; X = C or Si) monolayers. We demonstrate that 14 ABX3 monolayers possess good stability and high Fermi velocities. The FPC3, ClPC3, BrPC3, and FAsC3 monolayers exhibit a pristine n-type self-doping Dirac cone due to the interactions of electrons between the A-B units and C6 rings, which is beneficial for realizing high-speed carriers. Interestingly, the ClPSi3 monolayer exhibits remarkable responses to strain because a self-doping Dirac cone can be induced by relatively small in-plane biaxial strains (-5%), and the current-voltage (I-V) curves verified that the response strength is 11.57 times that of the graphene-based strain sensor at a bias of 1.10 V, indicating that the ClPSi3 monolayer could be used as a potential excellent strain sensor.

Crystalline Structures and Energetic Properties of Lithium Pentazolate under Ambient Conditions.

Recently, it has been reported that high-pressure synthesized lithium pentazolates could be quenched down to ambient conditions. However, the crystalline structures of LiN5 under ambient conditions are still ambiguous. In this work, the structures of LiN5 compound were directly explored at atmospheric pressure by using a new constrain structure search method. By using this method, three new allotropes were confirmed, and they show lower energy than the previous reported LiN5 phases. Both their thermodynamic and dynamic stability were confirmed through formation enthalpies, phonon spectrum, and ab initio molecular dynamics simulations under ambient conditions. Moreover, these three allotropes show similar formation enthalpies and properties, which suggests that it is hard to obtain a single LiN5 phase, which is well consistent with the experimental phenomenon. Furthermore, because of their low formation energy, all of them possess low energy density when they directly decompose to Li3N and nitrogen (0.52 kJ/g). Instead, the decomposed energy could be further improved to 3.78 kJ/g when they decompose under an oxygen-rich environment.

An Attitude Prediction Method for Autonomous Recovery Operation of Unmanned Surface Vehicle.

The development of launch and recovery technology is key for the application to the unmanned surface vehicle (USV). Also, a launch and recovery system (L&RS) based on a pneumatic ejection mechanism has been developed in our previous study. To improve the launch accuracy and reduce the influence of the sea waves, we propose a stacking model of one-dimensional convolutional neural network and long short-term memory neural network predicting the attitude of the USV. The data from experiments by "Jinghai VII" USV developed by Shanghai University, China, under levels 1-4 sea conditions are used to train and test the network. The results show that the stabilized platform with the proposed prediction method can keep the launching angle of the launching mechanism constant by regulating the pitching joint and rotation joint under the random influence from the wave. Finally, the efficiency and effectiveness of the L&RS are demonstrated by the successful application in actual environments.

[Study on HPCE fingerprints of Poecilobdella manillensis from Guangxi province].

OBJECTIVE: To establish fingerprints for Poecilobdella manillensis from Guangxi province using the high performance capillary electrophoresis (HPCE) method. METHOD: Electrophoresis was performed on a fused silica capillary column (75 microm x 56 cm), with 25 mmol x L(-1) Na2HPO4-120 mmol x L(-1) Tris-16 mmol x L(-1) SDS (adjusted to pH 12.0 with 1 mol x L(-1) NaOH ) as the running buffer. The applied voltage was 17 kV, the temperature was 25 degrees C and the detection wavelength was 254 nm. The sample's hydrodynamic injection was 3.4 kPa x 6s and the duration was 27 min. RESULT: HPCE fingerprint was established with 13 common peaks. The similarity between fingerprints of P. manillensis in 10 batches and control fingerprints was more than 0.98. CONCLUSION: The method is so precise, reproducible and stable that it could be used as a new means for the quality control of P. manillensis.

Comparative study on the protective effects of Yinchenhao Decoction against liver injury induced by alpha-naphthylisothiocyanate and carbon tetrachloride.

OBJECTIVE: To optimize the animal model of liver injury that can properly represent the pathological characteristics of dampness-heat jaundice syndrome of traditional Chinese medicine. METHODS: The liver injury in the model rat was induced by alpha-naphthylisothiocyanate (ANIT) and carbon tetrachloride (CCl(4) ) respectively, and the effects of Yinchenhao Decoction (, YCHD), a proved effective Chinese medical formula for treating the dampness-heat jaundice syndrome in clinic, on the two liver injury models were evaluated by analyzing the serum level of alanine aminotransferase (ALT), asparate aminotransferase (AST), alkaline phosphatase (ALP), malondialchehyche (MDA), total bilirubin (T-BIL), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) as well as the ratio of liver weight to body weight. The experimental data were analyzed by principal component analytical method of pattern recognition. RESULTS: The ratio of liver weight to body weight was significantly elevated in the ANIT and CCl(4) groups when compared with that in the normal control (P<0.01). The contents of ALT and T-BIL were significantly higher in the ANIT group than in the normal control (P<0.05,P<0.01), and the levels of AST, ALT and ALP were significantly elevated in CCl(4) group relative to those in the normal control P<0.01). In the YCHD group, the increase in AST, ALT and ALP levels was significantly reduced (P<0.05, P<0.01), but with no significant increase in serum T-BIL. In the CCl(4) intoxicated group, the MDA content was significantly increased and SOD, GSH-PX activities decreased significantly compared with those in the normal control group, respectively (P<0.01). The increase in MDA induced by CCl(4) was significantly reduced by YCHD P<0.05). CONCLUSION: YCHD showed significant effects on preventing liver injury progression induced by CCl(4), and the closest or most suitable animal model for damp-heat jaundice syndrome may be the one induced by CCl(4).

Quality evaluation of Yin Chen Hao Tang extract based on fingerprint chromatogram and simultaneous determination of five bioactive constituents.

A completely validated method based on HPLC coupled with photodiode array detector (HPLC-UV) was described for evaluating and controlling quality of Yin Chen Hao Tang extract (YCHTE). First, HPLC-UV fingerprint chromatogram of YCHTE was established for preliminarily elucidating amount and chromatographic trajectory of chemical constituents in YCHTE. Second, for the first time, five mainly bioactive constituents in YCHTE were simultaneously determined based on fingerprint chromatogram for furthermore controlling the quality of YCHTE quantitatively. The developed method was applied to analyze 12 batches of YCHTE samples which consisted of herbal drugs from different places of production, showed acceptable linearity, intraday (RSD <5%), interday precision (RSD <4.80%), and accuracy (RSD <2.80%). As a result, fingerprint chromatogram determined 15 representative general fingerprint peaks, and the fingerprint chromatogram resemblances are all better than 0.9996. The contents of five analytes in different batches of YCHTE samples do not indicate significant difference. So, it is concluded that the developed HPLC-UV method is a more fully validated and complete method for evaluating and controlling the quality of YCHTE.