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As a rising star, the fuel cell will be applied very broadly. However, when the fuel cell works at a high current, too much water yield and the redundancy water block the air or oxygen enter the fuel cell, then the power reduces sharply. The gas diffusion layer (GDL) in the fuel cell is the critical component to transfer water and gas. A novel GDL was prepared in this paper to improve transferability. The new GDL consists of one carbon paper and two microporous layers. The microporous layer close to carbon paper is modified by pore-former CaCO3. The total thickness of the new GDL is 270 μm; then, the samples were pressed to 220, 240, and 260 μm by rolling, respectively. The electrochemical impedance spectroscopy tests at a large current (2.5 A/cm2) show that the fuel cell with 240 μm GDL has relatively small transmission impedance regardless of high or low humidity. The results show that the new GDL can significantly improve the water transferability of the proton exchange membrane fuel cell.

We constructed a piezoelectric rotatable magnetic force microscope (MFM) that works in a 10 T cryogen-free superconducting magnet. The piezoelectric tube is deformed tangentially and drives a bearing under the inertial drive principle so the MFM head can obtain rotary movement. Due to the novel piezoelectric design, the MFM can be hung underneath the heat sink via a soft spring, and it can be rotated in a cryogen-free superconducting magnet so that the direction of the magnetic field can be changed from 0° to 90° continuously. The system functions in magnetic fields of up to 10 T in any direction relative to the tip–sample geometry. This is the first piezoelectric rotatable MFM ever reported. Using this homemade rotatable MFM, we imaged the structure of magnetic tracks on a commercial videotape. When the magnetic field angle changes from 0° to 90°, the magnetic moments on the tape and probe tip also rotate. A magnetic field strength of 0.8 T parallel to the sample surface is required to fully rotate the magnetic moment of the tip we used, but 0.8 T is not enough to fully rotate the magnetic moment of the sample. The piezoelectric rotatable MFM is expected to be widely used to study the anisotropy of magnetic materials due to its superiority in obtaining the same high field in and out of plane (compared with a vector magnet) as well as in maintaining the same scan area precisely (compared with a mechanical rotatable MFM, especially for atomic-scale scan areas).

Maintaining friction matching is the core issue for non-inertial piezo motors (PMs); this challenge severely limits their application in complex conditions such as variable temperature environments. To address this issue, a compact, optimal friction self-matching PM with non-inertial driving is reported in this paper. The motor is implemented with a narrow 5.5 mm-outer diameter piezoelectric scanner tube (PST) whose outer electrode is equally divided into two independently controllable PSTs. The PST, divided into two parts, clamps a sapphire rod between dual sapphire ball structures at both ends and an elastically supported sapphire ball at the centre. The device features a balanced normal force distribution scheme that allows friction forces acting on the sapphire rod at both ends and on the intermediate section to be approximately equal along the axial direction of the PST, achieving automatic optimal matching of friction, then it can operate like an inchworm motor. The feasibility of this scheme is verified by testing with a low threshold voltage down to 35 V at room temperature and 160 V at liquid nitrogen temperature. The motor dimensions are 5.5 mm × 5.5 mm ×35 mm (length × width × height). At room temperature, step size ranges from 0.1 μm to 1 μm. It has a maximum stroke about 5 mm and a maximum load of 40 g. This PM’s extreme compactness, low machine tolerance requirements, and smooth sequence make it ideally suited for building superior quality, atomically resolved scanning probe microscopy devices compatible with narrow spaces and extreme conditions.

The monitoring systems of various industries have various types and different structures. There are problems of “data chimney” and “information islands”. Monitoring data is difficult to be effectively utilized and cannot provide reliable data information to support for environmental security. In this end, an environment monitoring system based on micro-service architecture is designed. The information management and automatic monitoring business systems are unified into a flexible, robust and efficient system platform to adapt to the big data analysis and the mining applications. Using Hadoop to build environment monitoring big data platform, distributed storage, selective extraction and efficient calculation of the massive environment monitoring data can be achieved. By integrating the detection and monitoring data of the ecological environment and in-depth mining it, a neural network model is established to automatically identify potential safety hazards and recommend corresponding treatment measures, so to assist in the comprehensive research and scientific decision-making of environmental safety and promote intelligent management of safety.

We present a two-degree-of-freedom piezoelectric motor, which is driven by a simple cross-shaped piezo unit. Here, not only the structure of high novelty and simplicity but also the working principle is new. The cross-shaped piezo unit is sandwiched between top and bottom guiding plates with roughly equal pressing forces applied between the four free ends of the piezo unit and the plates. The working principle is as follows: A pair of opposite arms of the piezo unit quickly and simultaneously expand and contract periodically in the X direction, which results in a vanishing total friction force in the X direction; meanwhile, the other two arms in the Y direction deform slowly in a push–pull manner, which will move the aforementioned X-direction arms a step in the Y direction; then, the Y direction piezo arms restore their initial states slowly one by one. Repeating these actions will produce continuous stepping in the Y direction. Because the structure is symmetric in X and Y directions, we can similarly produce stepping in the X direction. The advantages are obvious: compact, rigid, and planar, which are all important for high stability and, hence, crucial in building an atomically resolved scanning probe microscope.

The gas diffusion layer (GDL) is an important component in the proton exchange membrane fuel cell (PEMFC), and the main function of GDL is to transfer water and gas. This paper explores the effect of the gradient hydrophobicity of GDL on the proton exchange membrane fuel cell (PEMFC). The gradient GDL design uses two microporous layers (MPL). First, polytetrafluoroethylene (PTFE) : carbon black in MPL near the carbon paper side was fixed at 3 : 7, and then the content of PTFE : carbon black in MPL near the catalyst layer (CL) was set to 3 : 7, 2 : 8 and 1 : 9. Second, the fixed PTFE : carbon black in MPL near the carbon paper side was 2 : 8, and the PTFE : carbon black in MPL near CL was 2 : 8 and 1 : 9. We found that, when near the carbon paper side and PTFE : carbon black = 3 : 7, GDL can obtain good cell performance through gradient hydrophobic treatment. Moreover, when near the carbon paper side and PTFE : carbon black = 2 : 8, the cell performance did not change much after GDL gradient hydrophobic treatment. We found that when GDL is subjected to a gradient hydrophobic treatment, the content of PTFE and carbon black must be rationally allocated to obtain good water management capabilities.

Scanning tunneling microscopes (STMs) that work in ultra-high vacuum and low temperatures are commonly used in condensed matter physics, but an STM that works in a high magnetic field to image chemical molecules and active biomolecules in solution has never been reported. Here, we present a liquid-phase STM for use in a 10 T cryogen-free superconducting magnet. The STM head is mainly constructed with two piezoelectric tubes. A large piezoelectric tube is fixed at the bottom of a tantalum frame to perform large-area imaging. A small piezoelectric tube mounted at the free end of the large one performs high-precision imaging. The imaging area of the large piezoelectric tube is four times that of the small one. The high compactness and rigidity of the STM head make it functional in a cryogen-free superconducting magnet with huge vibrations. The performance of our homebuilt STM was demonstrated by the high-quality, atomic-resolution images of a graphite surface, as well as the low drift rates in the X–Y plane and Z direction. Furthermore, we successfully obtained atomic-resolution images of graphite in solution conditions while sweeping the field from 0 to 10 T, illustrating the new STM’s immunity to magnetic fields. The sub-molecular images of active antibodies and plasmid DNA in solution conditions show the device’s capability of imaging biomolecules. Our STM is suitable for studying chemical molecules and active biomolecules in high magnetic fields.

Proton exchange membrane fuel cell (PEMFC) is a promising automotive power source that has been gradually applied due to its many advantages such as pollution-free and low-temperature start-up. The gas diffusion layer (GDL) is a key component for water and gas management in PEMFC. It can directly affect the performance of PEMFC. In this paper, we prepared a new type of GDL with hierarchical pores to improve the performance of PEMFC at high current density. The new GDL mainly includes a commercial carbon paper layer and two microporous layers on the same side of carbon paper. The microporous layer near carbon paper was modified with pore former, and another layer was produced without pore former. The pore size of the middle microporous layer was controlled by the content of pore former and times of sonication. From the results of the polarization curve, electrochemical impedance spectroscopy, water contact angle, conductivity, and pore size distribution, it was found that GDL with hierarchical pores shows obvious advancement than commercial GDL. The PEMFC performance was tested to compare the new and commercial GDL. The results show that the peak power of our GDL at 100% humidity reaches 1.24 W/cm2 and the limit current density is 3.500 A/cm2. The modification of the pore size of the microporous layer near the carbon paper side can improve the water management ability of the fuel cell.

The effect of phosphorus poisoning on the catalytic behavior of diesel oxidation catalysts was investigated over model and supplier monolith catalysts, i.e., Pd–Pt/Al2O3. The results of ICP and XPS from the vapor-phase poisoning over model catalysts suggested that the temperature of phosphorus poisoning affects both the overall content of phosphorus and the dispersion of phosphorus (i.e., inlet/outlet and surface/bulk). Phosphorus oxide (P2O5), metaphosphate (PO3−), and phosphate (PO43−) were identified in the poisoned model and supplier catalysts. The distribution of these species on poisoned model catalysts was highly dependent on the poisoning temperature, i.e., a higher temperature resulted in a higher concentration of PO43−. The outlets of the monoliths contained more PO43− and less P2O5 than the inlets. Both active sites and surface OH groups on model and supplier catalysts were contaminated upon phosphorus poisoning. It is found that PO43− had a stronger influence on the active sites than P2O5. One significant finding in this study is that the vapor-phase phosphorus poisoning could be a practical and cost efficient approach to simulate an accelerated aging/poisoning process.

The combination of photonic and plasmonic elements with complementary optical properties has stimulated the development of optoplasmonic hybrid systems, in which photonic and plasmonic elements can interact synergistically, breaking through the limitations of traditional structures. In this paper, a new optoplasmonic tweezer is theoretically proposed by using the Au nanobowtie and

Combined with photonic microstructure and plasmonic nanostructure, the optoplasmonic hybrid structure with fantastic optical properties attracts lots of attentions in recent years. With the help of light enrichment by dielectric photonic microenvironment, the embedded plasmonic nanoantennas generate much greater electromagnetic field enhancement at surface for light harvesting compared to conventional plasmonic nanostructures. In this work, a sandwich optoplasmonic hybrid structure is developed for surface enhanced Raman spectroscopy (SERS) detection, which is consisted of polymethyl methacrylate (PMMA) microspheres array, self-assembled Ag nanoparticles (AgNPs) film and SiO2 microsphere (PMMA@AgNPs@SiO2). The SERS spectra collected on this optoplasmonic substrate point out it has high sensitivity with limit of detection (LOD) at 10 fM. The experimental data demonstrate both the PMMA microarray and SiO2 microsphere play important roles in enrichment of light illuminating at AgNPs for SERS detection, which is confirmed by the simulated electric field distributions. This sandwich optoplasmonic hybrid structure not only enlarges research field of surface plasmon, but also provides a novel SERS subtract for sensitive analysis in chem/bio-field.

Magnetic circular dichroism (MCD) and magnetic linear dichroism (MLD) have been investigated in a photoemission electron microscopy (PEEM) system excited by a deep ultra-violet (DUV) laser (with λ = 177.3 nm and hυ = 7.0 eV) for the first time. High resolution PEEM magnetic images (down to 43.2 nm) were directly obtained on a (001)-oriented magnetic FePt film surface with a circularly-polarized light under normal incidence. Furthermore, a stepped Cr seeding layer was applied to induce the formation of large-area epitaxial FePt films with (001) and (111) two orientations, where MLD with large asymmetry was observed in the transition area of two phases. It demonstrates that DUV laser can be a powerful source for high resolution magnetic imaging in the laboratory in absence of synchrotron facilities.

This study investigates the photocatalytic degradation of caffeine (CAF) under solar light (290–1200 nm) irradiation using two different photocatalysts (i.e. TiO2 and ZnO). The adsorption of CAF on both photocatalysts follows Freundlich adsorption isotherm in the pH range of 6.0–8.0 with Kf values 0.0012 L mg−1 and 0.00097 L mg−1 for ZnO and TiO2 respectively at pH 7.0. A comprehensive parametric study shows that for both photocatalysts the optimum reaction conditions are pH 7.0, light intensity of 100 mW cm-2 and photocatalyst amount of 1.0 g L−1. The photocatalytic degradation of CAF follows pseudo first-order kinetics irrespective of the photocatalyst used. The apparent rate constants (Kapp) of solar photocatalytic degradation of CAF were determined as 0.032 min−1 and 0.024 min−1 for TiO2 and ZnO respectively. The degradation rate constant (Kr in mg L−1 min−1) of CAF with ZnO is directly proportional to the incident light intensity (I0.79). In the case of TiO2, it does not depend on I when I ≤ 60 mW cm-2. However, it increases when I > 60 mW cm-2. The present paper shows that solar light coupled with unmodified TiO2 or ZnO can be successfully used to degrade caffeine in water.

We present atomic-resolution images of TiSe $_2$ , MoTe $_2$ and TaS $_2$ single crystals in liquid condition using our home-built scanning tunneling microscopy (STM). By facilely cleaving of single crystals in liquid, we were able to keep the fresh surface not oxidized within a few hours. Using the high-stable home-built STM, we have obtained atomic resolution images of TiSe $_2$ accompanied with the single atom defects as well as the triangle defects in solution for the first time. Besides, the superstructure of MoTe $_2$ and hexagonal charge-density wave domain structure in nearly commensurate phase of TaS $_2$ were also obtained at room temperature (295 K). Our results provide a more efficient method in investigating the lively surface of transition metal dichalcogenides. Besides, the high stable liquid-phase STM will support the further investigations in liquid-phase catalysis or electrochemistry.

We present a homebuilt scanning tunneling microscope (STM) which employs an inner-wall polished sapphire guiding tube as a rail for the scanner to form a short tip-sample mechanical loop. The scanner is mounted on a square rod which is housed in the guiding tube and held by a spring strip. The stiff sapphire guiding tube allows the STM body to be made in a simple, compact and rigid form. Also the material of sapphire improves the thermal stability of the STM for its good thermal conductivity. To demonstrate the performance of the STM, high quality atomic-resolution STM images of high oriented pyrolytic graphite were given.

The transient earth voltage (TEV) will be superposed on the shell when the Disconnector switch is operated if the reactive compensation device (RCD) is installed in the substation. The partial separation element method (PSEM) is used to obtain the frequency variation parameters of the equipment in this paper, and the mathematical analysis method is used to calculate the TEV installed in the RCD substation. The amplitude frequency characteristic curve of TEV and the influence of RCD installation position on the corresponding amplitude of TEV main frequency are obtained by the simulation analysis. The influence of SCSR inlet capacitance and series compensation to ground capacitance on the corresponding amplitude of TEV main frequency is completed. The results show that the TEV oscillation of GIS is more intense when the installation of RCD in substation, the peak value of TEV has no obvious change, and the amplitude corresponding to the main frequency of TEV has been greatly increased. TEV decreases when the distance between RCD and GIS increases. The change of series compensation to ground capacitance will not affect the main frequency amplitude of TEV.

The DC bias of AC transformer will be caused by grounding electrode which pour DC into the ground, DC bias is affected by the ground condition near the ground electrode, the parameters of power equipment and lines, and the operation mode of power grid, among which the geodetic parameters near the ground electrode are uncertain factors. In this paper, a method of estimating geodetic parameters is proposed. The probability statistics of moments of random variables are obtained according to the probability distribution of random factors or random disturbances. The uncertain parameters are estimated such as earth resistivity and equivalent area, and the error analysis of uncertain factors is completed. The simulation validation of the estimation method is carried out, and the variation of the ground potential with uncertainties is given, which provides data support for the calculation of DC bias in the expansion of DC project.

The temperature-induced structure variation and its effect on physical properties is pivotal in material preparation for devices application. Motivated by surface scanning tunnel microscope (STM) measurement of ${T}_{d}\ensuremath{-}{\mathrm{MoTe}}_{2}$ single crystal at low temperature, temperature dependent electronic structure, lattice dynamics, and topological properties are explored to understand the microscopic origin of the observed anisotropic negative thermal expansion and abnormal STM images below 70 K. Remarkably, we find that the nonequivalent Te atoms in ${T}_{d}\ensuremath{-}{\mathrm{MoTe}}_{2}$ have qualitatively different contributions to both phonon spectra and electronic structures. The in-plane longitudinal acoustic mode and the ${\mathrm{Te}}_{(2)}$ atoms are found to play an important role in uniaxial negative thermal expansion and the temperature dependent electronic phase transition, respectively. Interestingly, under the scalar relativistic approximation, a band renormalization occurs, accompanied by a Dirac phase transition from type II to type I, upon cooling below 70 K. Introducing spin-orbit coupling induces a temperature dependent semimetal--semiconductor transition. Our results explain the experimental phenomena very well: abnormal surface STM image below 70 K does not originate from the displacement of the Te atoms but the band renormalization owing to strong electron-lattice coupling.

The combination of photonic and plasmonic elements with complementary optical properties has stimulated the development of optoplasmonic hybrid systems, in which photonic and plasmonic elements can interact synergistically, breaking through the limitations of traditional structures. In this paper, a new optoplasmonic tweezer is theoretically proposed by using the Au nanobowtie and S i O 2 microsphere. The finite-difference time-domain simulation is used to study the influence of the size of the S i O 2 microsphere and the S i O 2 hemisphere in polydimethylsiloxane on the optical potential well. The simulation results show that the electric field intensity of the structure is increased by 6 times compared with the Au nanobowtie structure, and the gradient force and the trapping potential are also significantly improved.

We report cryogenic magnetic force microscopy studies of anisotropic-strained (La0.8Pr0.2)2/3Ca1/3MnO3/NdGaO3(0 0 1) thin films. Real-space magnetic imaging reveals a robust charge-ordered insulating (COI) magnetic phase with a strong relaxation feature. Remarkably, in the first melting and reappear-then-melting processes, the ferromagnetic metallic (FMM) domain configurations differ dramatically, showing a droplet-like and a stripe-like pattern, respectively. These observations illustrate that the FMM nuclei are randomly self-organized distributed in the virgin highly COI-dominant phase separation state recorded after zero field cooling. Regardless of how to reach the saturated FMM state, the anisotropic nature of the long-range strain involves in and dominates to form well-ordered FMM stripes eventually. Our results facilitate the control and manipulation of phase separation morphology at the micrometer scale.

Damping structures of synchronous generator such as rotor damping bars, iron core and slot wedge can provide positive damping for the dynamic process of power system, while magnetic saturation, distortion and skin effect during the large disturbance process make the three-part damping appear nonlinear. In order to quantitatively describe the strength of three component damping effect during the large disturbance process, the time-step finite element method and the polynomial approximation method are coupled to study the Damping Torque Coefficient (DTC) during the large disturbance caused by the short-circuit fault. The influence of three component damping structure on DTC is studied. The damping strength of each component is obtained by comparing the individual and combined effect of three component damping structure. The results provide theoretical basis to the enhancement of power system stability by improving rotor damping structures of synchronous generators.

Intrinsic magnetism has recently been confirmed to survive in bilayer Cr2Ge2Te6. In this work, multiple domain structure and symmetry types and their transformations are firstly discovered in bulk layered Cr2Ge2Te6 crystal using a homebuilt magnetic force microscope (MFM). These transitions occur within a surprisingly narrow temperature range of 2 K and magnetic field range of 0.07 T, which colorful phenomenon hasn't been discovered in other materials but Cr2Ge2Te6. The MFM images show a series of basic domain patterns. Some of them also hasn't been found before, such as self-fitting disks and fine ladder structure within Y-connected walls. The symmetry of these magnetic domain patterns is discussed. The results not only are important in developing new magnetic domain theories but also may show some potential applications in storage depending on the future investigations.

We present a mechanical rotatable magnetic force microscope (MFM) with precise angle control that can be operated in a 7 T superconducting magnet. An inertial piezoelectric motor called a SpiderDrive was used for the coarse approach because of its high compactness, high rigidity, and small size. Due to the mechanical rotation design, the MFM head can be rotated in a 7 T superconducting magnet with a bore size of 89 mm so that the direction of the magnetic field can be changed from 0° to 90° continuously. The highest in-plane magnetic field strength tested was 7 T. This is the first rotatable MFM ever reported. Using the homemade rotatable MFM, we investigated a 40 nm thick La0.67Ca0.33MnO3 (LCMO) thin film on NdGaO3 (100) substrate with anisotropy, determining that the charge-ordering insulating (COI) phase of the LCMO disappears as the direction of the magnetic field changed from 0° to 90°. Furthermore, the ferromagnetic pattern, appearing as bright and dark contrasts and similar to that formed by the S and N of a magnet, was seen parallel to the direction of the magnetic field. The rotatable MFM in this paper is expected to be widely used in studying the anisotropy of magnetic materials.

Scanning tunneling microscopy (STM) can be used to image individual biological molecules, such as proteins, in vacuum or air. This requires sample dehydration and thus may not reflect the native state of the molecule. Extensive efforts have been made to image single proteins in solution using STM; however, the images have revealed only round or oval shapes with no sub-molecular details. Here, we present the sub-molecular features of streptavidin proteins under physiological conditions using a homebuilt low-leakage-current and highstability liquid phase STM. The N-lobe, C-lobe, and C-terminal tail of the epidermal growth factor receptor kinase domains were also resolved in solution. Our results demonstrate that the structure, morphology, and dynamics of a protein molecule can be examined under physiological conditions by the STM.

Static magnetic fields (SMFs) can affect cell proliferation in a cell-type and intensity-dependent way but the mechanism remains unclear. At the same time, although the diamagnetic anisotropy of proteins has been proposed decades ago, the behavior of isolated proteins in magnetic fields has not been directly observed. Here we show that SMFs can affect isolated proteins at the single molecular level in an intensity-dependent manner. We found that Epidermal Growth Factor Receptor (EGFR), a protein that is overexpressed and highly activated in multiple cancers, can be directly inhibited by SMFs. Using Liquid-phase Scanning Tunneling Microscopy (STM) to examine pure EGFR kinase domain proteins at the single molecule level in solution, we observed orientation changes of these proteins in response to SMFs. This may interrupt inter-molecular interactions between EGFR monomers, which are critical for their activation. In molecular dynamics (MD) simulations, 1-9T SMFs caused increased probability of EGFR in parallel with the magnetic field direction in an intensity-dependent manner. A superconducting ultrastrong 9T magnet reduced proliferation of CHO-EGFR cells (Chinese Hamster Ovary cells with EGFR overexpression) and EGFR-expressing cancer cell lines by ~35%, but minimally affected CHO cells. We predict that similar effects of magnetic fields can also be applied to some other proteins such as ion channels. Our paper will help clarify some dilemmas in this field and encourage further investigations in order to achieve a better understanding of the biological effects of SMFs.

Self-assembly/disassembly is ubiquitous in nature and plays an important role in many biological events. But noninvasive characterization of this process in real time at molecular resolution remains challenging. Herein, using homebuilt liquid-phase scanning tunneling microscopy (L-STM) with ultrahigh stability, we directly visualized enzymatic self-assembly/disassembly of oligopeptide nanofibers in real time for the first time. Static high-resolution L-STM images clearly showed the molecular packing details in the supramolecular nanofiber and the diameter of the nanofiber was consistent with that of cryo transmission electron microscopy (cryo-TEM) observations. Moreover, the self-repairing behavior of the supramolecular nanofibers was also directly observed at high resolution for the first time. This work unprecedentedly revealed new insights into Nature-mimic self-assembly and disassembly at the molecular level. It also illustrates the potential of our homebuilt L-STM in studying delicate biological processes in physiological solution with high resolution.