Robust and Tunable Ferroelectricity in Ba/Co Codoped (K_(0.5)Na_(0.5))NbO_(3) Ceramics

The 0.98(K_(0.5)Na_(0.5))NbO_(3)-0.02Ba(Nb_(0.5)Co_(0.5))O_(3-δ) ceramics with doped Ba^(2+) and Co^(2+) ions are fabricated,and the impacts of the thermal process are studied.Compared with the rapidly cooled (RC) sample,the slowly cooled (SC) sample possesses superior dielectric and ferroelectric properties,and an 11 K higher ferroelectricparaelectric phase transition temperature,which can be attributed to the structural characteristics such as the grain size and the degree of anisotropy.Heat treatment can reversibly modulate the content of the oxygen vacancies,and in turn the ferroelectric hysteresis loops of the samples.Finally,robust and tunable ferroelectric property is achieved in SC samples with good structural integrity.

Optical Neural Network Architecture for Deep Learning with Temporal Synthetic Dimension

The physical concept of synthetic dimensions has recently been introduced into optics.The fundamental physics and applications are not yet fully understood,and this report explores an approach to optical neural networks using synthetic dimension in time domain,by theoretically proposing to utilize a single resonator network,where the arrival times of optical pulses are interconnected to construct a temporal synthetic dimension.The set of pulses in each roundtrip therefore provides the sites in each layer in the optical neural network,and can be linearly transformed with splitters and delay lines,including the phase modulators,when pulses circulate inside the network.Such linear transformation can be arbitrarily controlled by applied modulation phases,which serve as the building block of the neural network together with a nonlinear component for pulses.We validate the functionality of the proposed optical neural network for the deep learning purpose with examples handwritten digit recognition and optical pulse train distribution classification problems.This proof of principle computational work explores the new concept of developing a photonics-based machine learning in a single ring network using synthetic dimensions,which allows flexibility and easiness of reconfiguration with complex functionality in achieving desired optical tasks.

Endoleak management and postoperative surveillance following endovascular repair of internal carotid artery vascular diseases using Willis covered stent

Background:To report the clinical results and experiences of endoleak management and postoperative surveillance following endovascular repair of internal carotid artery vascular diseases(ICAVDs)using Willis covered stents.METHODS:Seventy-three patients with ICAVD who received Willis covered stent implantation between November 2013 and September 2018 were retrospectively reviewed.The clinical data of endoleak management and postoperative surveillance were analyzed.RESULTS:Seventy-three cases with ICAVD,including 57 aneurysms,11 carotid-cavernous sinus fistulas(CCF),and 5 surgical injuries,were all successfully installed with covered stents.Total isolation of ICAVDs was achieved in 59 patients(80.8%),and endoleaks were observed in 14 patients(19.2%).Of the 14 patients with endoleaks,12 had type I endoleaks and 2 had type II;13 had aneurysms and one had CCF.10 patients with type I endoleaks received balloon dilatation,and 7 of them underwent a second stent-graft implantation after then.One patient with type II endoleak received embolization of the branch artery,and another one received follow-up observation.Endoleaks resolved in 6 patients and were minimal in 5 patients after balloon dilatation or the second stent implantation.During the follow-up period,minor endoleaks spontaneously resolved in 4 patients and minimal endoleaks were still demonstrated in 4 patients without enlargement of residual lumen and rupture.CONCLUSIONS:Endoleaks are the major complication after endovascular repair of ICAVDs and represent one of the limitations of this procedure.Improving the understanding and management of endoleaks can be beneficial in the clinical setting,including the popularization and application of this technique.

Efficiency and convergence of China’s export trade embodied carbon emissions

Based on the input-output data from 2002 to 2017,this paper combined the three-stage DEA model with the non-competitive I-O model and measured the embodied carbon efficiency of export trade in China’s 26 product sectors,and further investigated its influencing factors and convergence issues.The results of the study showed that:①The embodied carbon efficiency of export trade in China’s overall product sector demonstrated a positive development trend from 2002 to 2017,and this positive trend was more obvious after the implementation of conservation culture construction in 2012.But the differences of embodied carbon emission efficiency level among the product sectors were still significant.②Measured by the K-means clustering analysis method,this study found that agriculture,other service industries,wholesale and retail industries,catering industry,construction industry and manufacturing industry with strong innovation ability were mostly concentrated at high and medium efficiency levels,while industrial sectors with resource dependence and high energy consumption,such as metal smelting and rolling processing industries,non metallic mineral products industry,and coal mining industry,were at a low efficiency level.③All product sectors hadσconvergence,absoluteβconvergence and conditionalβconvergence during 2002-2010 and 2010-2017,and the level of each product sector in 2010-2017 was higher than that in 2002-2010 according to the perspective of convergence speed and degree of convergence.④Technological progress had not fully played a role in suppressing energy consumption and improving the efficiency of embodied carbon efficiency,and it would also widen the gap between the embodied carbon emission efficiency levels of various product sectors.The expansion of trade scale could effectively improve carbon emission efficiency and narrow the gap between sectors.Environmental regulation could effectively promote the improvement of embodied carbon emission efficiency but would widen the level gap between sectors.These findings indicate that China needs to build a sound environmental regulation system for the development of low-carbon trade,continue to reasonably expand the scale of trade,eliminate backward industries with production capacity,vigorously develop low-carbon technologies such as new energy,strengthen the exchange of low carbon technologies and industrial cooperation among sectors,and promote coordinated development among industries.

Preparation and performance of novel magnetic phase-change-microcapsule-supported Bi_(2)WO_(6)catalyst

The design and synthesis of novel photocatalyst with self-temperature control function is an important topic in the field of advanced environmental functional materials.In this work,submicron-sized magnetic phase change microcapsules composed of paraffin core and Fe_(3)O_(4)-loaded silica shell are prepared,on which the Bi_(2)WO_(6)crystals is grown in situ through hydrothermal reaction to obtain novel magnetic phase-change-microcapsule-supported Bi_(2)WO_(6)catalyst(MP@FS/BWO).The MP@FS/BWO has a paraffin encapsulation ratio of 57.1%,and the phase change enthalpy of 105.1 J/g in a temperature range of 50–60℃,which endows the MP@FS/BWO with a certain self-temperature regulation ability.MP@FS/BWO shows excellent catalytic performance in the decomposition of rhodamine B under the simulated sunlight irradiation.After the light source is turned off,it still has good catalytic ability by maintaining high temperature due to its temperature control function based on the phase transition process.The MP@FS/BWO can be easily recycled by magnetic separation and shows good structural stability and reusability.This work provides a new idea for the development of long-effect and energy-saving outdoor photocatalysts.

Preparation and Structure-Property Regulation Mechanism of Reversible Thermochromic Polydiacetylene

The thermochromic mechanism and the structure-property regulation principle of reversible thermochromic polydiacetylene(PDA)materials have always been a challenging issue.In this work,a series of diacetylene monomers(m-PCDA)containing phenyl and amide or carboxyl groups were synthesized from 10,12-pentacosadiynoic acid(PCDA)through the esterification or amidation reactions.The effects of the number and the distribution of the functional groups in m-PCDA molecules on their solid-state polymerization capability,and the thermochromic mechanism of their corresponding polymers(m-PDA)were investigated and discussed in detail.The results show that the m-PCDA monomers containing both benzene ring and groups that can form hydrogen bonding interactions have strong intermolecular interaction,and are easy to carry out the solid phase polymerization under 254-nm UV irradiation to obtain the corresponding new thermochromic m-PDA materials.The thermochromic behavior of m-PDA depends on its melting process.The initial color-change temperature(blue to red)is determined by the onset melting tem perature,and the temperature range in which reversible color recovery can be achieved by repeat heating-cooling treatment is determined by its melting range.According to the proposed thermochromic mechanism of PDA,various new PDA materials with precise thermochromic temperatu res and reversible thermochromic temperature ra nges can be designed and synthesized through the appropriate introduction of benzene ring and groups that can form hydrogen bonding interactions into the molecular structure of linear diacetylene monomer.This work provides a perspective to the precise molecular structure design and the property regulation of the reversible thermochromic PDA materials.

A Survey on Model Predictive Control of DFIGs in Wind Energy Conversion Systems

This paper presents a comprehensive study on the model predictive control(MPC)of doubly fed induction generators(DFIG)in wind energy conversion systems(WECS);in particular the MPC of the rotor side converter.The general principle of prevalent MPC strategies is discussed to introduce the theoretical framework in the first place.Furthermore,mainstream and high-performance MPC methods of DFIGs have been identified as model predictive current control(MPCC),model predictive torque control(MPTC),and model predictive power control(MPPC).Starting from analyzing dynamic models,these MPC strategies are investigated in terms of operating principles and technical developments.The paper further investigates implementation of MPC strategies in unbalanced grids.Based on the quantitative and qualitative analysis of several case studies,performance of various MPC schemes is compared and their special features are identified.Guidelines for designing MPC strategies of DFIGs in WECS are provided.

有机催化精准制备聚酯多元醇:环氧化物原位缓释与捕捉策略

基于低张力五元环张碳酸酯可控缓释环氧化物以及原位捕捉策略,开创了一种有机鎓盐PPNTFA(双(三苯基正膦基)三氟乙酸铵)催化的苯酐PA与环状碳酸酯(碳酸乙烯酯EC,碳酸丙烯酯PC)调节共聚反应,成功实现了苯酐聚酯多元醇的简便、高效、精准制备.在180℃下反应30 min,苯酐的转化率和聚合物产率均可达99%以上.通过改变链转移剂的种类和用量可以对目标聚合物微结构、拓扑结构和分子量(Mn,SEC=1300~17700 g/mol)等关键参数进行可控调节.而且,改变环状碳酸酯种类可以按需调整聚酯多元醇的骨架结构.

Efficient polymer-mediated delivery system for thiocyclam: Nanometerization remarkably improves the bioactivity toward green peach aphids

The unscientific application of synthetic pesticides has brought various negative effects on the environment,hindering the sustainable development of agriculture.Nanoparticles can be applied as carriers to improve pesticide delivery,showing great potential in the development of pesticide formulation in recent years.Herein,a star polymer(SPc)was constructed as an efficient pesticide nanocarrier/adjuvant that could spontaneously assemble with thiocyclam or monosultap into a complex,through hydrophobic association and hydrogen bonding,respectively,with the pesticide-loading contents of 42.54%and 19.3%.This complexation reduced the particle sizes of thiocyclam from 543.54 to 52.74 nm for pure thiocyclam,and 3814.16 to 1185.89 nm for commercial preparation(cp)of thiocyclam.Interestingly,the introduction of SPc decreased the contact angles of both pure and cp thiocyclam on plant leaves,and increased the plant uptake of cp thiocyclam to 2.4–1.9 times of that without SPc.Meanwhile,the SPc could promote the bioactivity of pure/cp thiocyclam against green peach aphids through leaf dipping method and root application.For leaf dipping method,the 50%lethal concentration decreased from 0.532 to 0.221 g/L after the complexation of pure thiocyclam with SPc,and that decreased from 0.390 to 0.251 g/L for cp thiocyclam.SPc seems a promising adjuvant for nanometerization of both pure and cp insecticides,which is beneficial for improving the delivery efficiency and utilization rate of pesticides.

A nano-delivery system expands the insecticidal target of thiamethoxam to include a devastating pest,the fall armyworm

Nano-delivery systems have been applied to deliver various synthetic/botanical pesticides to increase the efficiency of pesticide use and reduce the volumes of pesticides applied.Previous studies have supported the hypothesis that the nanocarriers can help expand the insecticidal target of pesticides to include non-target pests.However,the potential mechanism underlying this interesting phenomenon remains unclear.Herein,a widely applied star polycation(SPc)nanocarrier was synthesized to construct a thiamethoxam(TMX)nano-delivery system.The SPc-based delivery system could promote the translocation of exogenous substances across the membrane of Sf9 cells,increase the cytotoxicity of TMX against Sf9 cells by nearly 20%,and expand the insecticidal target of TMX to include Spodoptera frugiperda(the fall armyworm),with a 27.5%mortality increase at a concentration of 0.25 mg/mL.Moreover,the RNA-seq analysis demonstrated that the SPc could upregulate various transport-related genes,such as Rab,SORT1,CYTH,and PIKfive,for the enhanced cellular uptake of TMX.Furthermore,enhanced cell death in larvae treated with the TMX-SPc complex was observed through changes in the expression levels of death-related genes,such as Casp7,BIRC5,MSK1,and PGAM5.The SPc-based nano-delivery system improved the cellular uptake of TMX and expanded its insecticidal target by adjusting the expression levels of death-related genes.The current study mainly identified the transport and cell death genes related to nanocarrier-based insecticidal target expansion,which is beneficial for understanding the bioactivity enhancement of the nano-delivery system.

Study on the morphological regulation mechanism of hollow silica microsphere prepared via emulsion droplet template

The morphology regulation of hollow silica microspheres is significant for their properties and applications. In this paper, hollow silica microspheres were formed through the hydrolysis and condensation reaction of tetraethyl orthosilicate(TEOS) at the interface of the emulsion droplet templates composed of liquid paraffin and TEOS, followed by dissolving paraffin with ethanol. The effects of various factors including the emulsifier structure and content, TEOS content, catalyst type, and the ethanol content in the continuous water phase on the particle size, shell thickness and morphology of the prepared hollow silica microspheres were studied in detail. The results show that the diffusion and contact of TEOS and water molecules as well as the hydrolysis condensation reaction of TEOS at the oil-water interface are two critical processes for the synthesis and morphological regulation of hollow silica microspheres. Cationic emulsifier with a hydrophobic chain of appropriate length is the prerequisite for the successful synthesis of hollow silica microspheres. The ethanol content in water phase is the dominant factor to determine the average diameter of hollow microspheres, which can vary from 96 nm to 660 nm with the increase of the volume ratio of alcohol-water from 0 to 0.7. The silica wall thickness varies with the content and the hydrophobic chain length of the emulsifier, TEOS content, and the activity of the catalyst. The component of the soft template will affect the morphology of the silica wall. When the liquid paraffin is replaced by cyclohexane, hollow microspheres with fibrous mesoporous silica wall are fabricated. This work not only enriches the basic theory of interfacial polymerization in the emulsion system, but also provides ideas and methods for expanding the morphology and application of hollow silica microspheres.

An AIE Star Polymer with Enhanced Co-Delivery of Drug and Gene for Synergistic Pest Control

Pesticides,as the most common means of pest managements,have caused a series of problems such as pest resistance and environmental pollution.Aggregation-induced emission(AIE)polymers exhibit great potential in biological applications because their fluorescent intensities significantly enhance in the aggregated state.In this paper,an AIE star polymer including a tetraphenyl ethylene(TPE)core and poly(2-(dimethylamino)ethyl methacrylate)arms is designed and further developed as a multi-functional nanocarrier for agricultural pest control.The nanocarrier shows high water solubility,good size stability and AIE imaging ability.Meanwhile,the twisted AIE core and positively charged polymer arms make the nanocarrier efficiently co-load dinotefuran(DIN)and dsRNA via hydrogen bonds and electrostatic interactions,respectively.The AIE star polymer displays low toxicity and high fluorescence traceability.As a result,the nanocarrier co-loading with DIN and dsRNA exhibits a highly synergistic insecticidal effect with higher pest mortality compared to the separate delivery of DIN and dsRNA.This study develops the AIE star polymer to improve the efficiency of co-delivery of drug and dsRNA and proposes a new strategy toward efficient and synergistic pest control.

Nmnoparticle-mediated double-stranded RNA delivery system: A promising approach for sustainable pest management

RNA interference(RNAi)targeting lethal genes in insects has great potential for sustainable crop protection.Compared with traditional double-stranded(ds)RNA delivery systems,nanoparticles such as chitosan,liposomes,and cationic dendrimers offer advantages in delivering dsRNA/small interfering(si)RNA to improve RNAi efficiency,thus promoting the development and practice of RNAi-based pest management strategies.Here,we illustrate the limitations of traditional dsRNA delivery systems,reveal the mechanism of nanoparticle-mediated RNAi,summarize the recent progress and successful applications of nanoparticle-mediated RNAi in pest management,and finally address the prospects of nanoparticle-based RNA pesticides.

Increased globulin and its association with hemorrhagic transformation in patients receiving intra-arterial thrombolysis therapy

Previous studies have identified a diverse set of predisposing factors for the occurrence of hemorrhagic transformation （HT）, but the independent clinical predictors of HT after intra- arterial thrombolysis have not been determined. In this retrospective study, we investigated the characteristics of patients with or without HT who had received intra-arterial thrombolysis therapy, using biochemical analysis, renal function test, routine blood test, blood lipid test, coagulation blood test, liver function test, random blood glucose test, time- window for intra-arterial thrombolysis, recanalization, National Institutes of Health Stroke Scale （NIHSS） score and systolic blood pressure before intra-artedal thrombolysis. The mortality rates were similar in the HT and non-HT groups （P = 0.944）. In the single- factor analysis, patients with a higher globulin level （P 〈0.002）, prothrombin time activity percentage （PTA; P = 0.026）, and NIHSS score （P = 0.002）, had a significantly increased risk of developing HT. In the multifactor logistic regression model involving globulin level, PTA, white blood cell count, and NIHSS score, the globulin level （P 〈0.001; OR, 1.185; 95% confidence interval [CI], 1.090-1.288）, PTA （P = 0.018; OR, 1.016; 95% CI, 1.003-1.029）, white blood cell count （P = 0.025; OR, 1.097; 95% CI, 1.012-1.190） and NIHSS score （P = 0.003; OR, 1.097; 95% CI, 1.031-1.166） were significantly increased in the HT group. The increase in globulin level is an independent risk factor for HT in patients receiving intra-arterial thrombolysis. The possible mechanisms may involve inflammatory cytokines, matrix metalloproteinase 9, and positive acute-phase reactants synthesized by the liver.

Diferences and similarities of high-resolution computed tomography features between pneumocystis pneumonia and cytomegalovirus pneumonia in AIDS patients

Background:Accurately diferentiating pneumocystis from cytomegalovirus pneumonia is crucial for correct therapy selection in AIDS patients.Hence,the goal of this study was to compare the computerized tomography(CT)features of pneumocystis pneumonia and cytomegalovirus pneumonia in AIDS patients and identify clinical hallmarks to accurately distinguish these two pathologies.Methods:A total of 112 AIDS patients(78 with pneumocystis pneumonia and 34 cytomegalovirus pneumonia)at Beijing Ditan Hospital from January 2017 to May 2019 were included in this study.Two experienced chest radiologists retrospectively reviewed CT images for 17 features including ground-glass opacity,consolidation,nodules,and halo sign.Binary logistic regression analyses were conducted to identify the signifcant parameters that distinguished pneumocystis pneumonia from cytomegalovirus pneumonia.Correlations were analyzed by Pearson or Spearman correlation analyses.Result were considered signifcant if P<0.05.Results:The presence of consolidation,halo signs,and nodules(all P<0.05)were signifcantly more frequent in patients with cytomegalovirus pneumonia than in those with pneumocystis pneumonia.Small nodules(32.5%in cytomegalovirus pneumonia,6.41%in pneumocystis pneumonia,P<0.001)without perilymphatic distribution were particularly common in patients with cytomegalovirus pneumonia.Large nodules were not found in any of patients with cytomegalovirus pneumonia.The presence of ground-glass opacity,reticulation,and bronchial wall thickening(all P>0.05)were common in both groups.Conclusions:Analysis of consolidation,nodules,and halo signs may contribute to the diferential diagnosis of pneumocystis pneumonia or cytomegalovirus pneumonia.However,some CT features considered typical in one or other diseases appear with similar frequency in both cohorts of AIDS patients.CT features are potentially useful for the diferential diagnosis of pneumocystis pneumonia and cytomegalovirus pneumonia in AIDS patients.

Daily expression of two circadian clock genes in compound eyes of Helicoverpa armigera: evidence for peripheral tissue circadian timing

Circadian clock genes in peripheral tissues usually play an important role in regulating the circadian rhythms. Light is the most important environmental signal for synchronizing endogenous rhythms with the daily light-dark cycle, and compound eyes are known as the principal circadian photoreceptor for photic entrainment in most moths. However, there is little evidence for circadian timing in compound eyes. In the current study, we isolated the timeless gene, designated Ha-tim (GenBank accession number: KM233162), from the cotton bo 11 worm Helicoverpa armigera. Ha-tim and period (Haper) showed low messenger RNA levels in the compound eyes compared to the other tested adult organs. Ha-tim and Ha-per transcript levels were dependent on an endogenous rhythm that fluctuated over a daily cycle in the compound eyes and heads. The cycles of Hatim and Ha-per transcript levels followed similar time courses, and identical expression patterns of the two genes were observed in the compound eyes and heads. Ha-tim and Ha-per were dowregulated in the compound eyes after light exposure, copulation and starvation. These results indicated that Ha-tim and Ha-per transcript levels were regulated by endogenous and exogenous factors. Our study helped to improve our understanding of the circadian clock machinery in compound eyes and other peripheral tissues.

Nanocarrier-delivered dsRNA suppresses wing development of green peach aphids

RNA interference(RNAi)has developed rapidly as a potential“green”pest management strategy.At present,most studies have focused on the screening of aphid lethal genes,whereas only a few studies have been conducted on wing development,which is crucial for aphid migration and plant-virus dissemination.Here,the Myzus persicae genes vestigial(vg)and Ultrabithorax(Ubx)related to wing development,were cloned.These two genes were expressed in various tissues of 3rd-instar winged aphids.The mRNA level of vg was high in 3rd-instar nymphs,whereas the expression level of Ubx was high in adults.The nanocarrier-mediated delivery system delivered double-stranded RNAs for aphid RNAi using topical and root applications.The expression levels of vg and Ubx were downregulated by 44.0%and 36.5%,respectively,using the topical application.The simultaneous RNAi of the two target genes caused 63.3%and 32.2%wing aberration rates using topical and root applications,respectively.The current study provided a promising method for controlling aphid migration to alleviate the spread of insect transmitted plant diseases.

Phylogenomic tracing of asymptomatic transmission in a COVID-19 outbreak

SARS-CoV-2 has caused over 100 million deaths and continues to spread rapidly around the world.Asymptomatic transmission of SARS-CoV-2 is the Achilles’heel of COVID-19 public health control measures.Phylogenomic data on SARS-CoV-2 could provide more direct information about asymptomatic transmission.In this study,using a novel MINERVA sequencing technology,we traced asymptomatic transmission of COVID-19 patients in Beijing,China.One hundred and seventy-eight close contacts were quarantined,and 14 COVID-19 patients were laboratory confirmed by RT-PCR.We provide direct phylogenomic evidence of asymptomatic transmission by constructing the median joining network in the cluster.These data could help us to determine whether the current symptom-based screening should cover asymptomatic persons.

潜艇失事脱险艇员的分类救治探讨——以北约分类救治为例

我国目前尚缺乏针对援潜救生伤病员的分类救治系统。北约针对援潜救生过程中的伤病员情况进行分类救治。该分类系统基于病情危重程度,将疾病分为4类(T1、T2、T3和T4);根据是否需要加压治疗,将疾病分为2类(C1和C2)。另外,将救治场地分为5个区:分类区、一级治疗区、二级治疗区、三级治疗区和T4治疗区。笔者基于前期援潜救生的教学体会,对该分类救治系统存在的问题提出一些建议,为后期制定我国援潜救生分类救治系统提供借鉴。