聚(L-乳酸-co-衣康酸丁二醇酯)/中空介孔SiO_(2)微球复合薄膜的制备及对草莓包装中微气氛的调控作用

为改善聚(L-乳酸)(PLLA)薄膜的果蔬平衡气调包装性能,文中首先通过熔融酯化缩聚法将聚衣康酸丁二醇酯(PBI)作为柔性链段引入PLLA中制备PLBI共聚物,进一步通过溶液浇筑法将中空介孔SiO_(2)微球(HMSM)作为气体渗透“通道”填充到PLBI中制备PLBI/HMSM复合膜。探究了软段嵌入、HMSM粒径对复合膜包装性能的影响,并评估了薄膜对草莓包装内气氛的调控作用。结果表明,与PLLA相比,PLBI薄膜的Tg降低了5.4℃,断裂伸长率增加了14.3倍。继续添加质量分数0.9%700 nm的HMSM后,PLBI薄膜的CO_(2)透过率(CDTR)和O_(2)透过率(OTR)分别约为PLLA的2.2倍和3.3倍,而水蒸气透过率有所下降。草莓保鲜结果表明,在3~25 d的贮藏期间,PLBI/HMSM薄膜内的CO_(2)和O_(2)含量分别维持在6.9%~8.0%和3.1%~4.6%,可为草莓提供理想的保鲜微气氛,有效延缓了草莓的枯干和腐烂。

血液透析和腹膜透析对终末期肾脏病患者肠道菌群的影响

目的探讨血液透析和腹膜透析对终末期肾脏病(ESRD)患者肠道菌群的影响。方法选择健康对照者19名(健康对照组)、未透析的ESRD患者38例(未透析组)、持续腹膜透析的ESRD患者25例(PD组)、持续血液透析的ESRD患者27例(HD组),使用16S rDNA测序分析研究对象的粪便样品中肠道微生物群的组成和功能。结果与健康对照组比较,未透析的ESRD患者α多样性中的Simpson指数升高(P<0.05),未透析组、PD组、HD患者肠道菌群的α多样性Observed species指数、Chao1指数和Simpson指数比较差异均无统计学意义(P均>0.05)。β多样性分析显示4组之间物种组成结构比较差异有统计学意义(P均<0.05)。健康对照组及未透析组肠道菌群以拟杆菌门和厚壁菌门为主。与未透析组相比,HD组肠道菌群拟杆菌门减少(P<0.01)。4组研究对象的肠道菌群在科水平分类中比较差异有统计学意义的菌科有8个(P均<0.05),其中PD组和HD组肠道中普雷沃特尔菌科比例均较低。与未透析组比较,HD组肠道中毛螺菌科比例增加、脱硫弧菌科和紫单胞菌科比例降低;HD组肠道中理研菌科减少(P均<0.05)。与健康对照组相比,未透析组肠道中紫单胞菌科比例增加(P<0.05)。丹毒丝菌科比例在未透析组、PD组、HD组肠道中均有所增加,产碱菌科和韦荣氏菌科比例在健康对照组、未透析组、PD组肠道中相近,但在HD组肠道中降低(P均<0.05)。结论血液透析和腹膜透析治疗未明显破坏肠道菌群的多样性,但改变了ESRD患者肠道菌群的种类和数量。

The WNT1^(G177C) mutation specifically affects skeletal integrity in a mouse model of osteogenesis imperfecta type XV

The recent identification of homozygous WNT1 mutations in individuals with osteogenesis imperfecta type XV(OI-XV)has suggested that WNT1 is a key ligand promoting the differentiation and function of bone-forming osteoblasts.Although such aninfluence was supported by subsequent studies,a mouse model of OI-XV remained to be established.Therefore,we introduced a previously identified disease-causing mutation(G177C)into the murine Wnt1 gene.Homozygous Wnt1^(G177C/G177C)mice were viable and did not display defects in brain development,but the majority of 24-week-old Wnt1^(G177C/G177C)mice had skeletal fractures.This increased bone fragility was not fully explained by reduced bone mass but also by impaired bone matrix quality.Importantly,the homozygous presence of the G177C mutation did not interfere with the osteoanabolic influence of either parathyroid hormone injection or activating mutation of LRP5,the latter mimicking the effect of sclerostin neutralization.Finally,transcriptomic analyses revealed that short-term administration of WNT1 to osteogenic cells induced not only the expression of canonical WNT signaling targets but also the expression of genes encoding extracellular matrix modifiers.Taken together,our data demonstrate that regulating bone matrix quality is a primary function of WNT1.They further suggest that individuals with WNT1 mutations should profit from existing osteoanabolic therapies.

Strategies on Promoting Transformative Learning of College English Teachers

Based on the previous case study in promoting transformative learning of college English teachers,who participated in a three-month online training courses,the article made a further research and concluded four strategies on promoting transformative learning of college English Teachers.

Code acquisition method based on wavelet transform filtering

In order to improve the acquisition probability of satellite navigation signals, this paper proposes a novel code acquisition method based on wavelet transform filtering. Firstly, the signal vector based on the signal passing through a set of partial matched filters(PMFs) is built. Then, wavelet domain filtering is performed on the signal vector value. Since the correlation signal is low in frequency and narrow in bandwidth, the noise out-of-band can be filtered out and the most of the useful signal energy is retained.Thus this process greatly improves the signal to noise ratio(SNR).Finally, the detection variable when the filtered signal goes through the combination process is constructed and the detection based on signal energy is made. Moreover, for the better retaining useful signal energy, the rule of selection of wavelet function has been made. Simulation results show the proposed method has a better detection performance than the normal code acquisition methods under the same false alarm probability.

A New Multiple Gateway Transmit Diversity Technique for Future Satellite Networks

The next generation of High Throughput Satellite(HTS)will exploit Q/V band for the feeder link and Ka band for the user link.The exploitation of multiple gateways(GWs)is a transmit diversity measure to compensate severe rain attenuation of Q/V band feeder links.This paper introduces a new smart gateway diversity combination scheme that combinates N-active(K=2)and N+1 diversity method in detail from the working principle,gateway switching strategy,evaluation of system availability and implementation complexity.In addition,a feeder link outage event prediction algorithm featuring combination scheme is given detailly based on modified time-adaptive linear regression.Compared with the existing N+P scheme,the proposed scheme can provide higher system availability and more stable user’s experience under the condition of properly increasing the complexity of payload design.Compared with Nactive scheme that has been reported,it is much easier to implement in engineering and more cost-effective.As a result,the combination scheme is a realistic solution based on a trade-off between performance improvement and implementation complexity.

A Study of the English Translation Strategies of Chinese Film and Television Animation from the Perspective of Skopos Theory

The English translation level of domestic film and television animation not only affects the appreciation effect of English-speaking audiences,but also affects the communication and exchange of Chinese excellent culture in the world,and even affects the commercial interests of film and television production.With the increasing international exchange of various cultures,the traditional theoretical views on translation are no longer suitable for the enrichment and development of modern literary forms.Based on the Skopos Theory,this paper will discuss the translation strategies of film and television animation works and propose the translation methods of film and television animation,to enhance the communication and influence of Chinese culture.

Comparative Study of “Wolf Warriors II” and “Braveheart” from the Perspective of “Hero Tour”

The article takes the famous American writer and mythology scholar Joseph Campbell’s“Heroic Journey”theory as a clue to make a comparative study of“Braveheart”and“Wolf Warriors II”and analyze the cultural differences on heroic shaping between the Chinese and English.

低温自体血靶向回输对于非人灵长类脑卒中模型的神经保护作用

近几十年来,虽然研究已经证明治疗性低温在啮齿类动物脑卒中模型中有神经保护作用,但其临床转化却未能成功.可能的原因是不同物种之间的生物学差异以及转化研究中治疗性低温诱导难以有效实施.本研究介绍了一种基于非人灵长类动物缺血再灌注模型的选择性治疗性低温疗法,即将自体血于体外循环中冷却,在血管再通后立即通过微导管向缺血区域回输低温自体血.低温自体血将目标脑区迅速冷却至34℃以下,而核心温度可以维持在36℃左右.低温自体血回输减少了梗死面积,保留了白质完整性,改善了神经功能且未引发低温相关并发症.本研究结果表明,在非人灵长类动物脑卒中模型中,通过冷自体输血诱导治疗性低温是一种可行、快速和安全的方法.这提示低温自体血靶向回输是一种具有临床转化潜力的新型低温脑保护疗法.

A review and comparison of surface incident shortwave radiation from multiple data sources: satellite retrievals, reanalysis data and GCM simulations

Surface incident shortwave radiation(Rs)can promote the circulation of substance and energy,and the accuracy of its estimation is of great significance for climate studies.The Rs can be acquired from satellite retrievals,reanalysis predictions and general circulation model(GCM)simulations.Although Rs estimates have been evaluated and compared in previous studies,most of them focus on evaluating the Rs estimates over specific regions using ground measurements from limited stations.Therefore,it is essential to comprehensively validate Rs estimates from multiple data sources.In this study,ground measurements of 690 stations from BSRN,GEBA,CMA,GC-NET and buoys were employed to validate the Rs estimates from seven representative products(GLASS,GEWEX-SRB,CERES-EBAF,ERA5,MERRA2,CFSR and CMIP6).The validation results indicated that the selected products overestimated Rs globally,with biases ranged from 0.48 to 21.27 W/m^(2).The satellite retrievals showed relatively better accuracy among seven datasets compared to ground measurements at the selected stations.Moreover,the selected seven products were all in poor accuracy at high-latitude regions with RMSEs greater than 50 W/m^(2).The long-term variation trends were also analyzed in this study.

揭示Pd-Ag纳米颗粒尺寸对电催化甲醇氧化行为的影响

二元纳米颗粒中元素的分布状态与其电催化性能之间的构效关系对于设计高性能催化剂至关重要.本文通过改变高温冲击法的电流大小,快速制备出一系列具有不同颗粒尺寸和元素分布的Pd-Ag纳米颗粒.研究发现, 30 A冲击电流下得到的Pd-Ag纳米颗粒(PdAg-30A)在电催化甲醇氧化反应中表现出优异的催化性能以及抗CO毒化能力.结合分子动力学与原子芯能级模拟,研究得到了纳米颗粒结构在不同温度下演化的理论图像并据此建立了PdxAg@Ag模型.基于该模型的密度泛函模拟表明, PdAg-30A样品的高性能源于其较低的甲醇分子脱氢势垒和良好的CO+OH共吸附作用.这一研究结果表明了调控二元纳米颗粒中的元素分布在电催化甲醇氧化反应中的重要作用.

Temperature-driven phase transformation and element segregation in Pd-Ru immiscible alloy nanoparticles:Spatial resolving of elements and insights for electrocatalysis

Bimetallic alloys could form three typical structures including solid solution,heterostructure,and intermetallic compound,depending on the interactions between identical and different atoms.Although the trend can be predicted by the types of binary phase diagram,different synthetic protocols will trap the system in various kinetic intermediates among the three typical structures.Herein,we studied the phase evolution and elemental segregation in the alloy nanoparticles of immiscible Pd-Ru before and after thermal annealing.By developing an analysis method of local element segregation(LES)based on the energy dispersive spectroscopy(EDS)mapping signals,we were able to quantify the mixing of Pd and Ru atoms during the gradual phase transition from face-centered cubic(fcc)to hexagonal close packed(hcp).Density functional theory was also applied to calculate the energies of all possible PdRu4 structures(93 fcc models and 267 hcp models),which helps to rationalize the phase transition and element segregation.The annealing process also leads to the change of the electronic structure,which further influences the performance in the electrocatalytic hydrogen evolution reaction.The highest activity of PdRu4-400 was largely attributed to the proper interface between the Pd-rich fcc phase and Ru-rich hcp phase,as revolved by the above methods.

A point cloud segmentation method for power lines and towersbased on a combination of multiscale density features andpoint-based deep learning

The point segmentation of power lines and towers aims to use unmanned aerial vehicles(UAVs)for the inspection of power facilities,risk detection and modelling.Because of the unclear spatial relationship between the point clouds,the point segmentation of power lines and towers is challenging.In this paper,the power line and tower point datasets are constructed using Light Detection and Ranging(LiDAR)and a point segmentation method is proposed based on multiscale density features and a point-based deep learning network.First,the data are blocked and the neighbourhood is constructed.Second,the point clouds are downsampled to produce sparse point clouds.The point clouds before and after sampling are rotated,and their density is calculated.Next,a direct mapping method is selected to fuse the density information;a lightweight network is built to learn the features.Finally,the point clouds are segmented by concatenating the local features provided by PointCNN.The algorithm performs effectively on different types of power lines and towers.The mean interaction over union is 82.73%,and the overall accuracy can reach 91.76%.This approach can achieve the end-to-end integration of segmentation and provide theoretical support for the segmentation of large scenic point clouds.

Ultrathin SrTiO_(3)-based oxide memristor with both drift and diffusive dynamics as versatile synaptic emulators for neuromorphic computing

Artificial synapses are electronic devices that simulate important functions of biological synapses,and therefore are the basic components of artificial neural morphological networks for brain-like computing.One of the most important objectives for developing artificial synapses is to simulate the characteristics of biological synapses as much as possible,especially their self-adaptive ability to external stimuli.Here,we have successfully developed an artificial synapse with multiple synaptic functions and highly adaptive characteristics based on a simple SrTiO_(3)/Nb:SrTiO_(3)heterojunction type memristor.Diverse functions of synaptic learning,such as short-term/long-term plasticity(STP/LTP),transition from STP to LTP,learning–forgetting–relearning behaviors,associative learning and dynamic filtering,are all bio-realistically implemented in a single device.The remarkable synaptic performance is attributed to the fascinating inherent dynamics of oxygen vacancy drift and diffusion,which give rise to the coexistence of volatile-and nonvolatile-type resistive switching.This work reports a multi-functional synaptic emulator with advanced computing capability based on a simple heterostructure,showing great application potential for a compact and low-power neuromorphic computing system.

Quantitative prediction and evaluation of geothermal resource areas in the southwest section of the Mid-Spine Belt of Beautiful China

The geothermal resources in the southwest section of the Mid-Spine Belt of Beautiful China are abundant,but the quantitative prediction and evaluation of geothermal resources are very difficult. Based on geographic information system (GIS) and remote sensing (RS) platforms,six impact factors,namely land surface temperature,fault density,Gutenberg–Liszt B value,formation combination entropy,distance to river and aeromagnetic anomaly were selected. Through the establishment of the certainty factor model (CF),weights of the information entropy certainty factor model (ICF) and weights of the evidence certainty factor model (ECF),the geothermal potential in the study area were predicted quantitatively. Based on the ECF results,the six main geothermal resource areas were delineated. The results show that (1) ECF had high prediction accuracy (success index is 0.00405%,area ratio is 0.867);(2) The geothermal resource areas obtained were Ganzi–Ya’an–Liangshan,Panzhihua–Liangshan,Dali–Chuxiong,Nujiang–Baoshan,Diqing–Dali,and Lijiang–Diqing. The results provide a basis for the effective development and utilization of geothermal resources in the southwest section of the mid-ridge belt.

Seroprevalence of influenza viruses in Shandong,Northern China during the COVID-19 pandemic

Nonpharmaceutical interventions(NPIs)have been commonly deployed to prevent and control the spread of the coronavirus disease 2019(COVID-19),resulting in a worldwide decline in influenza prevalence.However,the influenza risk in China warrants cautious assessment.We conducted a cross-sectional,seroepidemiological study in Shandong Province,Northern China in mid-2021.Hemagglutination inhibition was performed to test antibodies against four influenza vaccine strains.A combination of descriptive and meta-analyses was adopted to compare the seroprevalence of influenza antibodies before and during the COVID-19 pandemic.The overall seroprevalence values against A/H1N1pdm09,A/H3N2,B/Victoria,and B/Yamagata were 17.8%(95%CI 16.2%–19.5%),23.5%(95%CI 21.7%–25.4%),7.6%(95%CI 6.6%–8.7%),and 15.0(95%CI 13.5%–16.5%),respectively,in the study period.The overall vaccination rate was extremely low(2.6%).Our results revealed that antibody titers in vaccinated participants were significantly higher than those in unvaccinated individuals(P<0.001).Notably,the meta-analysis showed that antibodies against A/H1N1pdm09 and A/H3N2 were significantly low in adults after the COVID-19 pandemic(P<0.01).Increasing vaccination rates and maintaining NPIs are recommended to prevent an elevated influenza risk in China.

Stress and Springback Analyses of API X70 Pipeline Steel Under 3-Roller Bending via Finite Element Method

3-Roller bending is a widely applied manufacturing process, particularly in structural steel pipe industry.However, due to the difficulty and high cost of measuring stress distribution inside sheet material via traditional method,internal stress/strain response during forming is largely unexplored. The focuses of this study are two:(1) to map the radii of curvature as well as the stress inside the work piece during forming by utilizing the meshing mechanism of finite element method, and(2) to further provide some numeric guidelines for the configuration of the rolling system in order to improve production efficiency and product quality. The results of this study indicate that:(1) it is crucial to properly choose forming parameter in order to produce product with desired radii;(2) much like a gradual springback process, the radii of curvature gradually increase from the top roller to the exit-side bottom roller;(3) under the assumptions made in this study, to produce pipes with a specified diameter with varying configurations of the 3-roller system will not significantly change the final residual stress; and(4) finally, shifting of the neutral axis up to 2.0% of the thickness toward the compressing side during the forming process is observed.

A Review of Engine Fuel Injection Studies Using Synchrotron Radiation X-ray Imaging

Fuel spray characteristics directly determine the formation pattern and quality of the fuel/air mixture in an engine,and thus affect the combustion process.For this reason,the improvement and optimization of fuel injection systems is crucial to the development of engine technologies.The fuel jet breakup and atomization process is a complex liquid-gas two-phase turbulent flow system that has not yet been fully elucidated.Owing to the limitations of standard optical measurement techniques,the spray breakup mechanism and its interaction with the nozzle internal flow are still unclear.However,in recent years synchrotron radiation(SR)X-ray imaging technologies have been widely applied in engine fuel injection studies because of the higher energy and brilliance of third-generation SR light sources.This review provides a brief introduction to the development of SR technology and compares the critical parameters of the primary third-generation SR light sources available worldwide.The basic principles and applications of various X-ray imaging technologies with regard to nozzle internal structure measurements,visualization of in-nozzle flow characteristics and quantitative analyses of near-field spray transient dynamics are examined in detail.

Near-infrared chemiluminescent carbon nanogels for oncology imaging and therapy

Carbon nanogels(CNGs)with dual ability of reactive oxygen species(ROS)imaging and photodynamic therapy have been designed with selfassembled chemiluminescent carbonized polymer dots(CPDs).With efficient deep-red/near-infrared chemiluminescence(CL)emission and distinctive photodynamic capacity,the H2O2-driven chemiluminescent CNGs are further designed by assembling the polymeric conjugate and CL donors,enabling an in vitro and in vivo ROS bioimaging capability in animal inflammation models and a high-performance therapy for xenograft tumors.Mechanistically,ROS generated in inflammatory sites or tumor microenvironment can trigger the chemically initiated electron exchange luminescence in the chemical reaction of peroxalate and H2O2,enabling in vivo CL imaging.Meanwhile,part of the excited-state electrons will transfer to the ambient H2O or dissolved oxygen and in turn lead to the type I and type II photochemical ROS production of hydroxyl radicals or singlet oxygen,endowing the apoptosis of tumor cells and thus enabling cancer therapy.These results open up a new avenue for the design of multifunctional nanomaterials for bioimaging and antienoplastic agents.

A new strategy to improve the sensitivity and selectivity of dopamine detection

We applied the combination of in situ electrochemical liquid-phase microextraction and square-wave voltammetric stripping analysis for the first time as a highly sensitive and selective approach for the detection of dopamine. A mixed gel of graphene sheets and an ionic liquid of 1-octyl-3-methylimidazolium hexaflurophosphate(OMim PF6) was used as a micro liquid-phase to pre-concentrate dopamine by controlled potential electrolysis from an aqueous solution(as a donor phase), followed by square-wave voltammetric stripping detection. Under optimized conditions, a linear calibration curve was obtained in the range of 0.05 to 1.0 ?mol/L in the presence of excess ascorbic acid and uric acid. The detection limit has been found to be 8.0 nmol/L(S/N=3).