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At present, most of China's onshore wind farms use doubly-fed induction generators (DFIG) with small-capacity and and low-cost converters, but generally, these DFIGs can only operate within the slip rate range of ±30%, and can not be connected to the grid normally under low-speed conditions. In order to improve the output of DFIGs under low-speed conditions, the paper proposes a dual-mode grid-connection control scheme. The author first established an asynchronous mathematical model for stator shorting of doubly-fed motor to finally identify the value range of short-circuit resistance, and then put forward the dual-mode flexible switching strategy, that is, units operate in the asynchronous mode when the speed is low, and in the conventional doubly-fed mode when the speed is high, thus realizing power generation operation at low speed. The simulation results show that, at low speed, in the asynchronous mode, the rotor current distortion rate can be reduced by 50% and the power control accuracy is higher, with the power fluctuation amplitude controlled within 3 kW, compared with those in the doubly-fed mode, and after the flexible switching strategy is adopted, the transient impulse current can be reduced by more than 36% and the new steady state can be reached in only 150 ms. This verifies the validity and feasibility of the dual-mode grid-connection control strategy for DFIGs.

Liu Zhaoji, regarded as the pioneer inpsychology of aestheticeducation, developed his aesthetic education philosophy through three distinct stages: enlightenment, incubation, and establishment. This study explores Liu Zhaoji's key concepts, including the interdependency of aesthetic education and aesthetic psychology, the integration of art and beauty to foster comprehensive aesthetic education, the incorporation of aesthetics into various disciplines to promote holistic development, and the amalgamation of theoretical exploration with practical implementation in aesthetic education. These ideas have significant implications for the implementation of aesthetic education in contemporary school settings. In the present era, it is crucial for aesthetic education to adhere to psychological principles, enhance the effectiveness of aesthetic teaching, advocate for a holistic approach to aesthetic education, establish collaborative mechanisms for interdisciplinary aesthetic education, and draw from both the rich heritage of Chinese traditional culture and the experiences of modern life to cultivate a distinctive Chinese aesthetic education spirit, thereby improving and fortifying aesthetic education practices.

Protein lysine methyltransferases (PKMT) catalyze methylation of lysine residues on histone tails and non-histone targets. These important post-translational modifications affect the structure and compactness of chromatin, which in turn affects gene expression. There is growing evidence that genetic alterations in PKMT affect the normal expression of PKMT in tissues and thus exert oncogenic or tumor suppressor functions. The expression of PKMT has been found to be associated with the prognosis of tumor patients in a variety of solid tumors. In this review, we summarized the functions of three major PKMT, including EZH2, KMT2 family and SMYD family, and their roles in thyroid carcinoma.

All-inorganic CsPbBr3 perovskite solar cells (PSCs) have attracted more attentions due to the excellent environmental stability, however, the wide bandgap and relatively poor crystallinity of CsPbBr3 have been the main obstacle to improve their power conversion efficiency (PCE). Herein, we proposed an efficient and simple strategy of precursor additive in the two-step aqueous-solution method, the resulted CsPbBr3 film has achieved more uniform grain size, almost pure perovskite phase, smoother surface, less defects, enhanced light absorption and longer carrier lifetime. This is due to the rapid evaporation of additive (IPA and CH3OH) in the CsBr/H2O precursor leads to a relatively higher local CsBr concentration on the surface of PbBr2, which can provide more nucleation sites and accelerate the crystallization of perovskite. Further, when utilizing the optimal additive of 5% (in volume) IPA, the HTM-free carbon-based CsPbBr3 PSCs obtained a PCE improvement from 9.09% to 10.29%, and an ultrahigh fill factor (FF) of 85.21%. What is more, by adding 0.1 mol/L PbCl2 into the PbBr2 solution in the first step, the open circuit voltage of device has increased from 1.36 V to 1.48 V, the champion PCE reached 10.37% (steady output PCE of 10.17%), and the non-encapsulated device could maintain 85% of its initial efficiency after 50 d in the air. This work provides a cost-effective approach to grow CsPbBr3 film and boosts the efficiency benchmark of the CsPbBr3 PSCs to more than 10%, it is desirable that the highly efficient and stable CsPbBr3 PSCs can be developed in future.

Abstract Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) are related RNA viruses responsible for severe respiratory infections and resulting disease in infants, elderly, and immunocompromised adults1–3. Therapeutic small molecule inhibitors that bind to the RSV polymerase and inhibit viral replication are being developed, but their binding sites and molecular mechanisms of action remain largely unknown4. Here we report a conserved allosteric inhibitory site identified on the L polymerase proteins of RSV and HMPV that can be targeted by a dual-specificity, non-nucleoside inhibitor, termed MRK-1. Cryo-EM structures of the inhibitor in complexes with truncated RSV and full-length HMPV polymerase proteins provide a structural understanding of how MRK-1 is active against both viruses. Functional analyses indicate that MRK-1 inhibits conformational changes necessary for the polymerase to engage in RNA synthesis initiation and to transition into an elongation mode. Competition studies reveal that the MRK-1 binding pocket is distinct from that of a capping inhibitor with an overlapping resistance profile, suggesting that the polymerase conformation bound by MRK-1 may be distinct from that involved in mRNA capping. These findings should facilitate optimization of dual RSV and HMPV replication inhibitors and provide insights into the molecular mechanisms underlying their polymerase activities.

Aiming at the blind spots of university language course learning in the age of artificial intelligence, this paper builds a technical framework of intelligent cultivation method with a university language intelligent question bank, classroom student behavior recognition model, and intelligent teaching evaluation model as the main modules. The knowledge point mastery model is constructed, the knowledge point test question matrix is composed, and the learner similarity calculation is carried out to design the intelligent question bank. Introduce the YOLO algorithm to solve the problem of occlusion and small target detection of students’ behavioral actions, and propose a student behavior recognition model based on the improved YOLOv5. Intelligent selection of language teaching evaluation indexes, adoption of the recursive goal evaluation method, and establishment of the teaching evaluation model. In the evaluation of the cultivation method, HZ University is used as the research site, and experimental and control classes are set up to conduct comparative experiments. The language score of the experimental class is significantly higher than that of the control class by 4.83 points (P

In the operating environment of power system with weak grid characteristics, the traditional current source converter control mode is prone to vibration, which increases the crossing difficulty and off-grid probability of wind turbines. Based on virtual synchronous generator (VSG) technology, a novel control strategy of voltage source converter is designed in this paper, and the voltage source converter control mode and current source converter control mode are studied. Under normal grid-connected operation conditions, voltage source converter control mode is adopted. Active power control increases active power compensation through VSG, and reactive current is injected into the front end of reactive power control. Under start-stop and high & low-voltage ride-through conditions, the current source converter control mode is adopted. The control strategy combines the advantages of voltage source converter control mode and the current source converter control mode. It has not only the frequency support characteristics, but also the fast active and reactive power response capability. The simulation and prototype experiments on the grid-connection process, active and reactive power response and high & low-voltage ride-through process of the full-power wind power converter are carried out. The results show that the proposed control scheme can achieve good control effect under each operating condition of the wind power converter, so that the wind power units have good steady-state and dynamic performance, and can well adapt to the demands of new energy grid-connection.

Long noncoding RNAs (lncRNAs) are increasingly being implicated as key regulators of cell proliferation, apoptosis, and differentiation. However, the molecular mechanisms of specific lncRNAs in the context of hypertrophic scar remain largely unclear. Here, we find that the lncRNA FPASL (fibroblast proliferation-associated LncRNA) is downregulated in HS, and FPASL reduces fibroblast proliferation and colony formation and blocks cell cycle progression. Using GO annotation enrichment analysis along with AZC (a specific inhibitor of DNA methylation), we identify that DNA methylation is responsible for downregulating FPASL in hypertrophic scar. Subsequent studies demonstrate that high expression of DNMT3b inhibits FPASL expression in HS. Mechanistic study reveals a significant increase in fibroblast proliferation after transfection with LNA-FPASL, which is further inhibited by knockdown of DNMT3b. Thus, our study reveals that DNMT3b mediates hypermethylation of the lncRNA FPASL promoter and the downregulation of lncRNA FPASL promotes fibroblast proliferation in hypertrophic scar.

620 ℃ thermal aging was carried out on full Cu3Sn solder joints for various duration, the microstructure evolution of solder joints were investigated. The mechanical properties of solder joints after aging were characterized by nano indentation test and shear test. The results show that, during the thermal aging, the Cu20Sn6 is first precipitated in planar along Cu/Cu3Sn interface, it grows continuously until the complete consumption of Cu3Sn. Subsequently, Cu20Sn6 transforms to two-phase layer, which consists of Cu20Sn6 and Cu13.7Sn. As the aging time increases, Cu13.7Sn is precipitated in waves at the Cu/two-phase layer interface by consuming the two-phase layer and grows continuously until it occupies the entire interface area. Meanwhile, there is growth in the number and size of voids in the middle of the solder joint, which eventually coalesces into microcracks. The hardness of Cu20Sn6, Cu3Sn and Cu13.7Sn phases are 9.62, 7.15, 4.67 GPa, and the elasticity modulus are 146.5, 134.0, 133.2 GPa, respectively.With the increase of aging time, the shear strength of solder joints increases first and then decreases, and remains more than 20.1 MPa within 120 min. The fracture morphology and fracture path also change.

Perovskite/silicon tandem solar cells have garnered considerable interest due to their potential to surpass the Shockley–Queisser limit of single-junction Si solar cells. The rapidly advanced efficiencies of perovskite/silicon tandem solar cells benefit from the significant improvements in perovskite technology. Beginning with the evolution of wide bandgap perovskite cells towards two-terminal (2T) perovskite/silicon tandem solar cells, this work concentrates on component engineering, additives, and interface modification of wide bandgap perovskite cells. Furthermore, the advancements in 2T perovskite/silicon tandem solar cells are presented, and the influence of the central interconnect layer and the Si cell on the progression of the tandem solar cells is emphasized. Finally, we discuss the challenges and obstacles associated with 2T perovskite/silicon tandem solar cells, conducting a thorough analysis and providing a prospect for their future.

At present, the installed capacity of new energy power generation equipment shows a trend of rapid growth. A higher proportion of new energy generation will make the power grid show the characteristics of high impedance, low inertia, weak damping and low short circuit ratio. However, traditional double-fed wind power converter usually adopts current source control mode, which is difficult to adapt to the increasingly harsh operating environment of power grid. Therefore, this paper studies a voltage source control mode of double-fed wind power converter, compares its performance with current source converter control mode, and proposes a switching method between voltage source converter control mode and current source converter control mode in the case of high voltage ride-through and low voltage ride-through. Through real-time network voltage monitoring, the converter control modes of voltage source and current source can be smoothly switched. Simulation results show that the proposed control scheme has good steady-state and dynamic performance, and can adapt to the requirements of new energy grid-connection.

Wide-bandgap (WBG) perovskite solar cells (PSCs) are essential for highly efficient and stable silicon/perovskite tandem solar cells. In this study, we adopted a synthetic strategy with lead thiocyanate (Pb(SCN)2) additive and methylammonium chloride (MACl) posttreatment to enhance the crystallinity and improve the interface of WBG perovskite films with a bandgap of 1.68 eV. The excessive PbI2 was formed at grain boundaries and converted into MAPbI3−xClx perovskites, which are utilized to form the graded heterojunction (GHJ) and compressive strain. This is beneficial for passivating nonradiative recombination defects, suppressing halide phase segregation, and facilitating carrier extraction. Subsequently, the device with GHJ delivered a champion efficiency of 20.30% and superior stability in ambient air and under 85 °C. Finally, we achieved a recorded efficiency of 30.91% for 4-terminal WBG perovskite/TOPCon tandem silicon solar cells. Our findings demonstrate a promising approach for fabricating efficient and stable WBG PSCs through the formation of GHJ.

Background: To adapt the scientific evaluation tool for the confusion evaluation of health rumors and to test this tool to the confusion evaluation of coronavirus disease 2019 (COVID-19)-related health rumors on Chinese online platforms during the outbreak period of COVID-19in China. Methods: The design of our study was systematic evaluation of COVID-19-related health rumors. Retrieved from 7 rumor-repellent platforms, rumors about COVID-19 were collected during the publication from December 1, 2019, to February 6, 2020, and their origins were traced. Researchers evaluated rumors using the confusion evaluation tool in 6 dimensions(creators, evidence selection, evidence evaluation, evidence application, backing and publication platform, conflict of interest). Items were scored using a seven-point Likert scale. The scores were converted into percentages, and the median of rumors from different sources was compared with rank-sum test. Results: Our research included 127 rumors. Scores were converted to percentages, median and interquartile range are used to describe the data. The median score: creators 25.00%(interquartile range, IQR, 16.67-37.50%), evidence selection 27.78% (IQR, 13.89-44.44%),evidence evaluation 33.33% (IQR, 25.00-45.83%), evidence application 36.11% (IQR, 22.22-47.22%), backing and publication platform 8.33% (IQR, 4.17-20.83%), conflict of interest75.00% (IQR, 50.00-83.33%). Almost 40% rumors came from WeChat and the rumors with the lowest scores were concentrated on the WeChat platform. The rumors about prevention methods have relatively lower scores. Conclusion: Most rumors included were not highly confusing for evaluators of this project.WeChat is the "worst-hit area" of COVID-19 related health rumors. More than half rumors focus on the description of prevention methods, which reflects the panic, anxiety and blind conformity of the public under public health emergencies.

The thermodynamic and kinetic basic theories of high temperature oxidation of metals and the theoretical conditions for the formation of protective oxide scale on FeCr alloys were described briefly. The characteristics of oxide scale structure and oxidation kinetics of traditional martensitic steel were summarized. Three new characteristics of oxidation behavior of new martensitic steel were summarized, namely good oxidation resistance, anomalous relationship between temperature and oxidation rate, and a special Cr-rich layer.It was pointed out that the oxidation behavior of some new martensitic steels is close to that of austenitic steels, and the oxidation resistance of martensitic steels was expected to be increased to the level of austenitic steels. The effect of Co, W and Si on the internal/external oxidation transition is the key research direction in the future.

Increasing evidence indicates that the oncoprotein murine double minute (MDM2) binding protein (MTBP) can be considered a pro-oncogene of human malignancies; however, its function and mechanisms in hepatocellular carcinoma (HCC) are still not clear. In the present work, our results demonstrate that MTBP could function as a co-activator of transcription factor E26 transformation-specific sequence (ETS-1), which plays an important role in HCC cell proliferation and/or metastasis and promotes proliferation of HCC cells. Using luciferase and real-time polymerase chain reaction (qPCR) assays, MTBP was found to enhance the transcription factor activation of ETS-1. The results from chromatin co-immunoprecipitation showed that MTBP enhanced the recruitment of ETS-1 to its downstream gene’s (mmp1’s) promoter region with ETS-1 binding sites. In cellular and nude mice models, overexpression of MTBP was shown to promote the proliferation of MHCC97-L cells with low endogenous MTBP levels, whereas the knockdown of MTBP led to inhibition of the proliferation of MHCC97-H cells that possessed high endogenous levels of MTBP. The effect of MTBP on ETS-1 was confirmed in the clinical specimens; the expression of MTBP was positively correlated with the downstream genes of ETS-1, mmp3, mmp9, and uPA. Therefore, by establishing the role of MTBP as a novel co-activator of ETS-1, this work expands our knowledge of MTBP or ETS-1 and helps to provide new ideas concerning HCC-related research.

The isothermal deformation behavior of Ni-Cr-Mo low alloy SA508Gr.4N steel at deformation temperature of 850-1200 ℃, strain rate of 0.001-1 s-1, and true strain of 0.9 was studied by using Gleeble-1500D thermal simulation testing machine.The physically based flow stress model including dynamic recovery and dynamic recrystallization and the dynamic recrystallization grain size model were established,and the suitable forging process to avoid the coarse grain structure heredities was put forward.The results show that as the deformation temperature increases and the strain rate decreases, the dynamic recrystallization volume fraction and grain size gradually increase; the true stress-true strain curve of SA508Gr.4N steel has an obvious discontinuous dynamic recrystallization phenomenon;by comparing the experimental value with the predicted value of the model, the correlation coefficient (R) and mean relative error (MRE) of the flow stress model are 0.998 and 4.76%, respectively, and the correlation coefficient (R) and mean relative error (MRE) of the dynamic recrystallization grain size model are 0.991 and 8.69%, respectively. The two models have high accuracy.

Objective To validate the agreement among the convolution neural network segmentation algorithm, Tada formula and manual segmentation for subdural/epidural hemorrhage volume. Methods A total of 129 cases with 352 subdural/epidural hemorrhage CT scans were extracted from Chinese Intracranial Hemorrhage Image Database (CICHID) from January 2017 to June 2019. All CT scans were measured by three methods including manual segmentation, algorithm segmentation and Tada formula. The manual segmentation was regarded as the "golden standard" and the agreement test among three methods was performed. We explored the influence factors in different measurement methods, such as the shape or boundary of hematoma. Results Compared with the Tada formula method, the percentage error of segmentation algorithm was small (23.62%), and the agreement between algorithm and the manual reference was strong, which 94.89% (334/352) of the data was within the 95% limits of agreement (95%LoA), however, the 95%LoA was broad. And the performance of segmentation algorithm showed better in asymmetry (P = 0.000) and clear boundary hematoma (P = 0.000). Conclusions The segmentation algorithm based on convolution neural network has a certain application prospect, but need to be validated in large sample research. doi：10.3969/j.issn.1672⁃6731.2021.03.011

Wide-bandgap all-inorganic CsPbIBr2 solar cells with MoOx/Ag/TeO2 composite transparent electrode have been firstly used to construct a 4T perovskite/Si-heterojunction tandem cells. The calculation results showed that the long wavelength transmission (600 to 1100 nm) of MoOx/Ag film can be enhanced remarkably by adding a TeO2 optical capping layer. This resulted in an obviously increase of the PCE (JSC) from 10.70% (17.56 mA/cm2) to 14.76% (24.67 mA/cm2) for corresponding bottom Si cell in CsPbIBr2/Si devices, although the PCE of top CsPbIBr2 cell decreased from 17.52% to 16.58%, the overall PCE of tandem device has increased from 28.22% to 31.34%. This JSC-dependent PCE improvement mainly came from the more balanced light absorption, which can be understood by the optical interference induced light field redistributions in CsPbIBr2/Si devices. Specially, comparing with the original Si cell, the JSC and PCE losses in bottom Si cell have been suppressed to about 33% and 32%, which are superior to most the reported pervoskite/Si tandem cells. Therefore, the tandem of Si cell and CsPbIBr2 cell with optimized MoOx(20 nm)/Ag(8 nm)/TeO2(50 nm) transparent electrode could be the promising cost-effective photovoltaic in the future. This work is instructive to the fabrication of pervoskite/Si tandem solar cells.

The application of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) has significantly improved the survival of patients with EGFR-mutant non-small cell lung cancer (NSCLC). However, there are still a portion of patients with poor efficacy and prognosis. Therefore, it is urgently needed to find effective emerging prognostic markers. In the past few years, tumor mutational burden (TMB) was mainly used to screen patients who benefitted from immunotherapy and predict the efficacy. Recently, there are also corresponding exploratory studies on EGFR-mutant NSCLC. In this review, we summarized the challenges of TMB test and latest clinical research in EGFR-mutant advanced NSCLC.

Abstract In the present work, two types of novel nano additives, titanium sulfonate ligand/black phosphorus (TiL4/BP) and titanium dioxide/black phosphorus (TiO2/BP) nanocomposites, were prepared. The tribological behavior of the steel/steel friction pairs lubricated by polyalphaolefins type 6 (PAO6) containing the nanocomposites under boundary lubrication was studied. The worn surfaces were analyzed using modern surface techniques. The experimental results show that the rubbed surfaces became smooth and showed little wear with the addition of the nanocomposites. TiO2/BP nanocomposites can significantly improve the lubricity of BP nanosheets under high contact stress. The synergistic roles of the load-bearing abilities and rolling effect of TiO2 nanoparticles, the slip induced by the BP with its layered structure, and the establishment of a tribofilm on the sliding interface are the basis of the tribological mechanisms.

Small heat shock proteins are protective proteins produced by organisms under thermal stress. They are widely present in living organisms. Here, Hsp18, Hsp18.55 and Hsp19.5 genes were cloned from Lactobacillus plantarum and heterologous expressed in Lactococcus lactis, and their potential functions under ethanol stress were investigated. The results showed that the recombinant strain over expressing Hsp19.5 gene had stronger stress resistance, which provided a basis for further study of the survival ability of other microorganisms under ethanol stress.

Objective: The primary aim of this systematic review was to examine the relationship of polycyclic aromatic hydrocarbon (PAH) exposure with cardiovascular diseases (CVDs) and elaborate the current knowledge and recent advances in the area of PAH and its effects on CVDs and discuss the growing epidemiological evidence linking PAH to CVDs on the health of human populations. In this systematic review, the increased risk of cardiovascular diseases and their relationship with PAHs were discussed in detail.Methods: On 05th April 2021, a systematic literature search was conducted using PubMed/Medline and Web of Science search engines in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The search was limited to articles that were written in English and dealt with human issues. All original peer-review publications were considered for inclusion. Comments, case reports, reviews, duplicated papers, and conference reports were excluded. Data was collected from included papers by two independent reviewers.Results: Conclusively, 20 research articles published between 2005 and 2021 were chosen for the final analysis. The systemic review included 20 studies with a variety of geographical studies. The most common research category among the nominated studies were time-series studies followed by retrospective cohort, cross-sectional, quasi-experimental, panel, and case-control studies. Most of the studies were conducted in the United States, whereas others were showed in various geographical countries around the world, such as Denmark, Germany, Finland, Netherlands, France, China, Norway, Korea, Sweden, Saudi Arabia, and Belgium. Eight studies assessed the association between PAH exposure and CVDs, four articles observed this relationship with blood pressure (BP), two observed association between atherosclerotic CVD and PAH, one congenital heart disease, cardiovascular events, and two with obesity. Furthermore, in some investigations, a favorable association between PAH exposure and hypertension as well as PAH exposure and obesity was found.Conclusion: In conclusion, this systematic review examined the relationship of PAH exposure with CVDs and CVD-related risk factors by searching several digital databases. After a comprehensive literature searches and summarizing findings from 20 articles, the authors concluded that a positive relationship was observed between PAH exposure and CVD risks.

Summary: A water-based spray-assisted growth strategy is proposed to prepare large-area all-inorganic perovskite films for perovskite solar cells (PSCs), which involves in spraying of cesium halide water solution onto spin-coating-deposited lead halide films, followed by thermal annealing. With CsPbBr3 as an example, we show that as-proposed growth strategy can enable the films with uniform surface, full coverage, pure phase, large grains, and high crystallinity, which primarily benefits from the controllable CsBr loading quantity, and the use of water as CsBr solvent makes the reaction between CsBr and PbBr2 immune to PbBr2 film microstructure. As a result, the small-area (0.09 cm2) and large-area (1.00 cm2) carbon-electrode CsPbBr3 PSCs yield the record-high efficiencies of 10.22% and 8.21%, respectively, coupled with excellent operational stability. We also illustrate that the water-based spray-assisted deposition strategy is suitable to prepare CsPbCl3, CsPbIBr2, and CsPbI2Br films with outstanding efficiencies of 1.27%, 10.44%, and 13.30%, respectively, for carbon-electrode PSCs.

C24H48N2O3, monoclinic, P21 (no. 4), a = 14.805(3) Å, b = 10.0557(18) Å, c = 18.061(3) Å, β = 98.935(5)°, V = 2656.3(8) Å3, Z = 4, Rgt(F) = 0.0674, wRref(F2) = 0.1955, T = 173 K.

To promote the performance of perovskite solar cells (PSCs), its theoretical power conversion efficiency (PCE) and high stability, elaborative defect passivation, and interfacial engineering at the molecular level are required to regulate the optoelectric properties and charge transporting process at the perovskite/hole transport layer (HTL) interfaces. Herein, we introduce for the first time a multifunctional dipole polymer poly(2-ethyl-2-oxazoline) (PEOz) between the perovskite and Spiro-OMeTAD HTL in planar n-i-p PSCs, which advances the PSCs toward both high efficiency and excellent stability by stimulating three beneficial effects. First, the ether–oxygen unshared electron pairs in PEOz chemically react with unsaturated Pb2+ on the perovskite surfaces by forming a strong Pb–O bond, which effectively reduces the uncoordinated defects on the perovskite surfaces and enhances the absorption ability of the resulting PSCs. Second, the dipole induced by PEOz at the perovskite/HTL interface can decrease the HOMO and LUMO level of Spiro-OMeTAD and optimize the band alignment between these layers, thereby suppressing the interfacial recombination and accelerating the hole transport/extraction ability in the cell. Third, the hygroscopic PEOz thin film can protect perovskite film from water erosion by absorbing the water molecules before perovskite does. Finally, the PEOz-modified PSC exhibits an optimized PCE of 21.86%, with a high short-circuit current density (Jsc) of 24.88 mA/cm2, a fill factor (FF) of 0.79, and an open-circuit voltage (Voc) of 1.11 V. The unencapsulated devices also deliver excellent operation stability over 300 h in an ambient atmosphere with a humidity of 30~40% and more than 10 h under thermal stress.

Perovskite solar cells (PSCs) based on the 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) hole transport layer have exhibited leading device performance. However, the instability caused by this organic function layer is a very important limiting factor to the further development of PSCs. In this work, the spiro-OMeTAD is doped with polymethyl methacrylate (PMMA), which is further used as the hole transport layer to improve the device stability. It is shown that the PMMA can effectively improve the moisture and oxygen resistance of spiro-OMeTAD, which leads to improved device stability by separating the perovskite layer from moisture and oxygen. The device efficiency can maintain 77% of the original value for PSCs with the PMMA-doped spiro-OMeTAD hole transport layer, under a natural air environment (RH = 40%) for more than 80 days. The results show that the moisture- and oxygen-resistant PMMA:spiro-OMeTAD hole transport layer is effective at improving the device performance.

H11 steel with mass fraction of Al (0.77% and 0) was treated by different quenching and tempering processes, and the variation of hardness and impact energy were systematically investigated. Moreover, carbide extraction at annealed, 1060℃ quenched, 1060℃ quenched + 510℃ tempered, 1060℃ quenched + 560℃ tempered, and 1060℃ quenched + 600℃ tempered were conducted. Finally, the type and morphology of carbides were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The main conclusions are as follows:(1) Al can improve the impact toughness and tempering hardness of H11 steel; however, it reduces the hardness of quenching. (2) Al can promote the dissolution of carbides and the homogeneity of elements during the austenitizing process. (3) Al can prevent the precipitation and accumulation of carbides during the tempering process, which is more obvious under 560℃. (4) Al can prevent the accumulation of carbon and alloy elements, such that (Fe,Cr)2C, MoC and Cr7C3 become more stable and suppresses the precipitation of (Fe,Cr)3C, Mo2C, and Cr23C6 during the tempering process.

In-phase (IP) and out-of-phase (OP) thermal-mechanical fatigue (TMF) tests of 4Cr5MoSiV1 hot work die steel were conducted in full reverse mechanical strain control in the temperature range of 400-700℃ by a TMF servo-hydraulic testing system (MTS®). The results indicate that, when the strain amplitude is ±0.50%, the OP TMF life of 4Cr5MoSiV1 steel is~60% of the IP TMF life. The stress-strain hysteresis loops show asymmetries for both IP and OP loading. IP loading leads to comprehensive mean stress, while OP loading gives rise to tensile mean stress in the temperature range of 400-700℃. The changes of maximum strain and peak temperature with maximum stress are inconsistent, and the stress relaxation phenomenon could be observed under IP and OP loading. Moreover, two kinds of TMF cycling exhibite continuous cyclic softening in the high temperature half stage, while in the low temperature half stage, cyclic hardening occurs initially and is then followed by continuous cyclic softening. The fractured surfaces under IP TMF loading display striation and tear ridge, and exhibits quasi-cleavage characteristics. In addition, the cracks are less but longer. However, fractured surfaces under OP TMF loading mainly display striation and dimple characteristics, and the cracks are shorter and more abundant.

The microcavity perovskite solar cells (PSCs) are designed by sandwiching the perovskite layer between the ultrathin Ag and opaque Ag electrodes. Compared to transparent-conductive-oxide (TCO) based PSCs, the microcavity PSCs with the bare Ag electrode show the poor optical performance due to the transmittance limit of Ag film. By introducing an optical coupling layer, the remarkably improved transmittance of the Ag electrode and enhanced light absorption in the perovskite layer are obtained. Furthermore, the better light absorption is available by adopting an optical spacer, and the resulted microcavity PSCs achieve the comparable or even higher JSC than TCO-based PSCs. This provides a guideline to design and fabricate efficient TCO-free PSCs.

A new sensing algorithm based on the ratio of the difference of maximum-minimum eigenvalues to geometric mean eigenvalue of the sampled covariance matrix is proposed. The algorithm uses the logarithmic distribution characteristics of geometric mean eigenvalue, through comparing the ratio and threshold value to determine whether the primary user occupies the distribution spectrum, and the prior knowledge of the primary signal and noise are not needed, but a simple closed-form expression of threshold is obtained. The simulation results show that the proposed algorithm can get better perceived performance under the conditions of low signal to noise ratio, few collaborative users and few samples. On the other hand, it has steady sensing performance, it will be less affected by either the extreme values or the false-alarm probability.

C29H54N2O3, monoclinic, P21 (no. 4), a = 9.8091(11) Å, b = 7.6661(8) Å, c = 19.095(2) Å, β = 93.171(4)°, V = 1433.7(3) Å3, Z = 2, Rgt(F) = 0.0657, wRref(F2) = 0.1362, T = 250 K.

C31H48N2O, orthorhombic, P212121 (no. 19), a = 6.530(2) Å, b = 11.728(4) Å, c = 35.236(12) Å, V = 2698.6(15) Å3, Z = 4, Rgt(F) = 0.0492, wRref(F2) = 0.1034, T = 173 K.

C28H42N2O2, monoclinic, P21 (no. 4), a = 12.679(3) Å, b = 6.9067(14) Å, c = 15.577(3) Å, β = 113.821(4)°, V = 1247.8(5) Å3, Z = 2, Rgt(F) = 0.0485, wRref(F2) = 0.1266, T = 173 K.

All-inorganic carbon-based CsPbIBr2 perovskite solar cells (PSCs) have attracted increasing interest due to the low cost and the balance between bandgap and stability. However, the relatively narrow light absorption range (300 to 600 nm) limited the further improvement of short-circuit current density (JSC) and power conversion efficiency (PCE) of PSCs. Considering the inevitable reflectance loss (~10%) at air/glass interface, we prepared the moth-eye anti-reflector by ultraviolet nanoimprint technology and achieved an average reflectance as low as 5.15%. By attaching the anti-reflector on the glass side of PSCs, the JSC was promoted by 9.4% from 10.89 mA/cm2 to 11.91 mA/cm2, which is the highest among PSCs with a structure of glass/FTO/c-TiO2/CsPbIBr2/Carbon, and the PCE was enhanced by 9.9% from 9.17% to 10.08%. The results demonstrated that the larger JSC induced by the optical reflectance modulation of moth-eye anti-reflector was responsible for the improved PCE. Simultaneously, this moth-eye anti-reflector can withstand a high temperature up to 200 °C, and perform efficiently at a wide range of incident angles from 40° to 90° and under various light intensities. This work is helpful to further improve the performance of CsPbIBr2 PSCs by optical modulation and boost the possible application of wide-range-wavelength anti-reflector in single and multi-junction solar cells.

The high-temperature plastic deformation and dynamic recrystallization behavior of SA508Gr.4N steel were investigated through hot deformation tests in a Gleeble1500D thermal mechanical simulator. The compression tests were performed in the temperature range of 1050-1250℃ and the strain rate range of 0.001-0.1s-1 with true strain of 0.16. The results show that from the high-temperature true stress-strain curves of the SA508Gr.4N steel, the main feature is dynamic recrystallization,and the peak stress increases with the decrease of deformation temperature or the increase of strain rate, indicating the experimental steel is temperature and strain rate sensitive material. The constitutive equation for SA508Gr.4N steel is established on the basis of the true stress-strain curves, and exhibits the characteristics of the high-temperature flow behavior quite well, while the activation energy of the steel is determined to be 383.862kJ/mol. Furthermore, an inflection point is found in the θ-σ curve, while the -dθ/dσ-σ curve shows a minimum value. The critical strain increases with increasing strain rate and decreasing deformation temperature. A linear relationship between critical strain (εc) and peak strain (εp) is found and could be expressed as εc/εp=0.517. The predicted model of critical strain could be described as εc=8.57×10-4Z0.148.

The Three Gorges Reservoir Area is an important ecological barrier and an important area of water conservation in China. Due to natural and man-made factors, the regional urbanization process is accompanied by soil erosion. In recent years, by actively implementing measures such as tree planting and afforestation, water and soil conservation projects, the forest coverage rate in the Chongqing Three Gorges Reservoir area has increased significantly, and soil erosion has been initially controlled. But the task of environmental protection in the Three Gorges Reservoir area is still arduous. This research analyzed the causes of soil erosion caused by the urban process, by collected and combed the data of soil erosion in the Three Gorges Reservoir area of Chongqing over the years. The causes of soil erosion in the Three Gorges Reservoir area caused by the urbanization process were deeply analyzed, we proposed to improve legislation and supervision; strengthen publicity and education of soil and water conservation; adopt new technology and technology and other governance countermeasures. The Three Gorges Reservoir is an important ecological barrier in the upper reaches of the Yangtze River. The control of soil erosion in the area has important ecological and social benefits for protecting the ecological environment of the Yangtze River Basin in China.