Search

A sliding-mode control (SMC) technology is widely used in inductor-capacitor-inductor (LCL)-filtered grid-tied inverters (GTIs) due to its strong robustness against parameter drift. However, under weak grid conditions, the steady performance of GTI using conventional pulsewidth-modulation-based SMC (PWM-SMC) degrades, resulting in increased harmonics in grid-injected currents. One reason is that the voltage feedforward term at the point of common coupling (PCC) in the SMC loop causes the phase margin of the inverter output impedance to decrease. Another reason is that the gain of conventional PWM-SMC-based systems is not high enough, especially under weak grid conditions. This article proposes a PCC feedforward voltage reconstruction method (named KF-PWM-SMC) for a PWM-SMC-based controller using Kalman filter (KF) estimation. As a result, the phase and magnitude of the inverter output impedance at the desired frequency can be significantly improved. Moreover, the proposed PCC feedforward voltage extraction method can save the PCC voltage control sensor, thereby improving the reliability of the whole system. A 3-kW experimental GTI based on the dSPACE DS1202 platform has been developed to verify the feasibility of the proposed control strategy.

BiSb was found to transform into a Weyl semimetal at ∼4 GPa. Detailed pressure-induced structural phase transitions and changes in electrical transport properties are explored.

In this study, oridonin-loaded long-circulating liposomes (LC-lipo@ORI) were prepared with the ethanol injection method. Its physicochemical properties and the morphology were characterized, and its stability and release profiles were evaluated. Furthermore, its antitumor effects were studied using two

CsPbI3 triggers strong interest in the photovoltaic community for their promising photoelectric property and nonvolatility. However, CsPbI3 layers with a-phase crystal structure are difficult for preparation, and these layers easily degrade to non-photoactive δ-phase at room temperature. Tuning the composition of precursor solutions is an important method for improving the properties of CsPbI3 layers. Herein, we prepare inorganic a-CsPbI3 perovskite solar cells using lead acetate as the lead source, which is different from conventional precursors with lead iodide as the lead source. The lead acetate precursor needs neither incorporating hydrogen iodide nor preparing PbI2 complex, and it is shown to enlarge the grain size, improve the crystallinity and reduce the trap density of CsPbI3 layers. By cooperating the lead acetate precursor with EDAI2 additive, the power conversion efficiency (PCE) of devices increases from 9.2% to 12.9% and the photo-stability of these devices is improved simultaneously.

Transition metal dichalcogenides (TMDs) have attracted wide attention due to their quasi-two-dimensional layered structure and exotic properties. Plenty of efforts have been done to modulate the interlayer stacking manner for novel states. However, as an equally important element in shaping the unique properties of TMDs, the effect of intralayer interaction is rarely revealed. Here, we report a particular case of pressure-tuned re-arrangement of intralayer atoms in distorted 1T-NbTe2, which was demonstrated to be a new type of structural phase transition in TMDs. The structural transition occurs in the pressure range of 16-20 GPa, resulting in a transformation of Nb atomic arrangement from the trimeric to dimeric structure, accompanied by a dramatic collapse of unit cell volume and lattice parameters. Simultaneously, a charge density wave (CDW) was also found to collapse during the phase transition. The strong increase in the critical fluctuations of CDW induces a significant decline in the electronic correlation and a change of charge carrier type from hole to electron in NbTe2. Our finding reveals a new mechanism of structure evolution and expands the field of pressure-induced phase transition.

Because electrostrictive materials are completely sealed and confined in a diamond anvil cell (DAC), their strain and atomic displacement excited by electric field cannot be in situ measured by gen...

It is known that metallization can greatly facilitate chemical reactions and dramatically change electric transport properties of materials. The search for materials displaying metallization at low...

The influence of grain sizes, size effects, has long been a key factor influencing the properties and even the phase transformation pathways of nanomaterials and has resulted in a lot of intriguing...

The electrical conduction mechanism of the hydrous minerals under high pressure is of great significance for understanding the high conductivity of the mantle and the Earth’s internal water. Theref...

Purpose. Aurantiamide acetate (AA) is a dipeptide derivative with complex pharmacological activities and remarkable effects on preventing and treating various diseases. In the current study, we aimed to investigate whether AA can exert protective effects in a mouse model of ALI induced by LPS. Materials and Methods. In this model, mice were given intranasal LPS for 3 days prior to receiving AA (2.5, 5, and 10 mg/kg) via oral gavage. An assessment of histopathological changes was performed by hematoxylin and eosin (HE). Proinflammatory cytokines were detected in bronchoalveolar lavage fluids (BALFs) by enzyme-linked immunosorbent assays (ELISAs). The effects of AA on protein expression of NF-κB and PI3K/AKT signaling pathways were determined by Western blot. In addition, lung wet/dry (W/D) weight ratio, myeloperoxidase (MPO) activity, cell counts, and protein content were also measured. Results. According to results, AA pretreatment significantly reduced lung pathological changes, W/D ratio, MPO activity, and protein content. Additionally, AA resulted in a significant reduction in the number of total cells, neutrophils, and proinflammatory cytokines in the BALF after LPS stimulation. The subsequent study revealed that pretreatment with AA dose dependently suppressed LPS-induced activation of NF-κB as well as PI3K/AKT phosphorylation. Conclusion. The results indicated that the AA had a protective effect on LPS-induced ALI in mice and could be a potential drug for ALI.

In situ impedance measurement and first-principles calculations have been performed to investigate the effect of high pressure (up to 35.5 GPa) on the dielectric properties of SrMoO4. It is found t...

There is proposed a tunable acoustic metamaterials cell composed of a micro-electromagnetic coil as the mass element and a magnetorheological elastomer (MRE) as cladding layer. The cell resonance frequency is changed by changing the magnetic field generated by the micro-electromagnetic coil to control the shear modulus of the MRE cladding layer. The tunable bandgaps, transmission loss, and waveguides of the tunable acoustic metamaterials are investigated using the finite element method. The results show that the bandgap frequency and width, the maximum attenuation frequency and transmission loss increase with the increasing of applied magnetic field strength. Meanwhile, without changing the structure of the acoustic metamaterials, the localization, guidance, demultiplex and multiplex of elastic waves can be realized by changing the cell resonance frequency. These results will greatly contribute to the application of tunable acoustic metamaterials in vibration control, new waveguides, and filter components.

In situ impedance measurement, resistivity measurements and first-principles calculations have been performed to investigate the effect of high pressure (up to 30.2 GPa) on the metallization and dielectric properties of GaP. It is found that the carrier transport process changes from mixed grain and grain boundary conduction to pure grain conduction at 5.8 GPa, and due to pressure-induced structural phase transition, the resistance drops drastically by three orders of magnitude at 25.5 GPa. Temperature dependence of resistivity measurements and band structure calculations suggest the occurrence of a semiconductor-metal transition. Combining differential charge density and dielectric analysis, it is observed that the electron localization is weakened, which leads to increased polarization and larger relative permittivity in the zb structure. After the phase transition, both the polarization and the relative permittivity decrease. Pressure increases the complex dielectric constant and dielectric loss factor, due to the increase in relaxation polarization and the scattering effect of carriers. Moreover, by comparing the high-pressure behavior of GaP, GaAs and GaSb, the changes in the electronic structure and electric transport process caused by the phase transition can be understood, which can enable us to better understand the metallization behavior and dielectric properties of Ga-based III-V family semiconductors under pressure, and stimulate the design and modification of other related group III-V semiconductors for optoelectronic devices and sensors.

Scheelite ABO4-type solid electrolytes have attracted much attention for potential applications as oxygen ionic conductors of solid oxide fuel cells. Herein, a systematic study was carried out on the electrical transport properties of CdMoO4 under high pressure by impedance spectroscopy measurements and theoretical calculations. The sequence of structural phase transitions at pressures was determined as I41/ a → C2/ c → P21/ c by the Crystal structure AnaLYsis by Particle Swarm Optimization (CALYPSO) method. A pressure-induced conduction transition from mixed ionic–electronic to pure electronic conduction was observed. Below 25.6 GPa, O2− ions play a major role in the electrical transport process. The microscopic transport mechanism was analyzed with grain boundary energies and migration energy barriers. Above 26.9 GPa, the grain boundary response was weakened significantly after a pressure cycle, and the grain boundary conductivity increased by about three times due to pressure. These results provide guidelines for the optimization and application of scheelite ABO4-based oxygen ionic conductors in solid oxide fuel cells.

In this work, a sandwich-type electrochemical immunosensor was fabricated to quantitatively detect hepatitis B surface antigen (HBsAg). The immunosensor was based on Rh core and Pt shell nanodendrites loaded onto amino group functionalized graphene nanosheet (RhPt NDs/NH2-GS) as label and gold nanoparticles loaded onto polypyrrole nanosheet (Au NPs/PPy NS) as platform. RhPt NDs with abundant catalytic active sites because of the branched core-shell structure, RhPt NDs/NH2-GS as the label displayed high catalytic activity, amplifying the current signal of the immunosensor. Additionally, Au NPs/PPy NS enhanced the electron transfer and provided a good microenvironment to immobilize antibodies effectively, thus improving the sensitivity of the immunosensor. Based on above advantages, the immunosensor emerged a linear concentration ranging from 0.0005 to 10 ng/mL, a low detection limit of 166 fg/mL for HBsAg (S/N = 3) and good stability, selectivity, reproducibility. Furthermore, the satisfactory accuracy in analysis of actual serum samples implied the immunosensor had promising prospect in clinical analysis applications.

Impedance spectroscopy (IS) is an indispensable method of exploring electrical properties of materials. In this review, we provide an overview on the specific applications of IS measurement in the investigations of various electrical properties of materials under high pressure, including electric conduction in bulk and grain boundary, dielectric properties, ionic conduction, and electrostrictive effect. Related studies are summarized to demonstrate the method of analyzing different electrical transport processes with various designed equivalent circuits of IS and reveal some interesting phenomena of electrical properties of materials under high pressure.

The quantitative detection of carcinoembryonic antigen (CEA) is significant to assess tumor status and therapeutic efficiency. In this study, a sandwich-type amperometric immunosensor for CEA detection sensitively was fabricated by novel signal amplification system. The signal amplification system was formed by gold nanoparticles loaded on amino functionalized graphene sheet (Au NPs/NH2-GS) and gold@palladium nanodendrites loaded on ferrous-chitosan functionalized polypyrrole nanotubes (Au@Pd NDs/Fe2+-CS/PPy NTs). Au NPs/NH2-GS as platform enhanced the electron transfer proven by apparent electron transfer rate constant. Au@Pd NDs/Fe2+-CS/PPy NTs nanocomposite as label appeared high catalytic activity to hydrogen peroxide reduction. Thus, the immunosensor showed wide linear concentration range (50 fg/mL to 50 ng/mL) and low detection limit of 17 fg/mL via amperometric i-t curve (i-t). Significantly, the nanocomposite can act as electroactive substance, which provided a good method to detect CEA without additional electroactive substance via square wave voltammetry (SWV). An overlapping linear concentration range (500 fg/mL to 5.0 ng/mL) was obtained compared i-t with SWV. The good reliability was verified mutually by i-t and SWV in actual sample analysis under overlapping linear concentration range. The detection method of without additional electroactive substance has vast potential for future development, due to simple testing condition.

Transition metal dichalcogenides (TMDs) have attracted wide attention due to their quasi-two-dimensional layered structure and exotic properties. Plenty of efforts have been done to modulate the interlayer stacking manner for novel states. However, as an equally important element in shaping the unique properties of TMDs, the effect of intralayer interaction is rarely revealed. Here, we report a particular case of pressure-tuned re-arrangement of intralayer atoms in distorted 1T-NbTe

A search-based strategy is useful for large-scale mining of microbiome data sets, such as a bird’s-eye view of the microbiome data space and disease diagnosis via microbiome big data. Here, we introduce Microbiome Search Engine 2 (MSE 2), a microbiome database platform for searching query microbiomes against the existing microbiome data sets on the basis of their similarity in taxonomic structure or functional profile., Metagenomic data sets from diverse environments have been growing rapidly. To ensure accessibility and reusability, tools that quickly and informatively correlate new microbiomes with existing ones are in demand. Here, we introduce Microbiome Search Engine 2 (MSE 2), a microbiome database platform for searching query microbiomes in the global metagenome data space based on the taxonomic or functional similarity of a whole microbiome to those in the database. MSE 2 consists of (i) a well-organized and regularly updated microbiome database that currently contains over 250,000 metagenomic shotgun and 16S rRNA gene amplicon samples associated with unified metadata collected from 798 studies, (ii) an enhanced search engine that enables real-time and fast (

The ionic transport properties of solid electrolyte LaF3 were systematically studied under high pressures up to 30.6 GPa with alternate-current impedance spectra measurements and first-principles calculations. From the impedance spectra measurements, LaF3 was found to transform from pure ionic conduction to mixed ionic and electronic conduction at 15.0 GPa, which results from the pressure-induced structural phase transition from a tysonite-type structure to an anti-Cu3Ti-type structure. F- ion migration can be suppressed by pressure, causing a decrease of the ionic conductivity of LaF3. By first-principles calculations, the pressure-dependent diffusion behaviors of the F- ions can be understood. The increased overlap of electron clouds at the interstitial site between rigid La3+ and liquid F- lattices leads to the appearance of electronic conduction in anti-Cu3Ti-type structured LaF3.