Stability of second order Hopfield neural networks with time delays

Dynamical behaviors of a class of second order Hopfield neural networks with time delays is investigated.The existence of a unique equilibrium point is proved by using Brouwer's fixed point theorem and the counter proof method,and some sufficient conditions for the global asymptotic stability of the equilibrium point are obtained through the combination of a suitable Lyapunov function and an algebraic inequality technique.

Three-dimensional numerical modeling of fullspace transient electromagnetic responses of water in goaf

The full-space transient electromagnetic response of water-filled goaves in coal mines were numerically modeled. Traditional numerical modeling methods cannot be used to simulate the underground full-space transient electromagnetic field. We used multiple transmitting loops instead of the traditional single transmitting loop to load the transmitting loop into Cartesian grids. We improved the method for calculating the z-component of the magnetic field based on the characteristics of full space. Then, we established the full- space 3D geoelectrical model using geological data for coalmines. In addition, the transient electromagnetic responses of water-filled goaves of variable shape at different locations were simulated by using the finite-difference time-domain （FDTD） method. Moreover, we evaluated the apparent resistivity results. The numerical modeling results suggested that the resistivity differences between the coal seam and its roof and floor greatly affect the distribution of apparent resistivity, resulting in nearly circular contours with the roadway head at the center. The actual distribution of apparent resistivity for different geoelectrical models of water in goaves was consistent with the models. However, when the goal water was located in one side, a false low-resistivity anomaly would appear on the other side owing to the full-space effect but the response was much weaker. Finally, the modeling results were subsequently confirmed by drilling, suggesting that the proposed method was effective.

ZnIn_2S_4 flowerlike microspheres embedded with carbon quantum dots for efficient photocatalytic reduction of Cr(Ⅵ)

Development of efficient heterostructured photocatalysts that respond to visible light remains a considerable challenge.We herein show the synthesis of ZnIn2S4/carbon quantum dot hybrid photocatalysts with flowerlike microspheres via a facile solvothermal method.The ZnIn2S4/carbon quantum dot flowerlike microspheres display enhanced photocatalytic and photoelectrochemical activity compared with that of pure ZnIn2S4.With a content of only 0.5 wt%carbon quantum dots,93%of Cr(VI)is reduced under visible‐light irradiation at 40 min.As a co‐catalyst,the carbon quantum dots improve the light absorption and lengthen the lifetime of charge carriers,consequently enhancing the photocatalytic and photoelectrochemical activity.

Multi-hole joint acquisition of a 3D-RVSP in a karst area:Case study in the Wulunshan Coal Field,China

Conventional surface seismic exploration in areas with complex surfaces such as karst landforms has been faced with the problem of poor excitation and reception conditions.RVSP(reverse vertical seismic profile)seismic exploration adopts a geometry in which the sources are downhole and receivers are on the ground which can reduce the influence of complex surfaces on seismic wave propagation(to some extent).Through numerical simulations and real data analysis,it was noted that in areas with complex surfaces and large numbers of underground karst caves,seismic waves generated in shallow boreholes are easily affected by various surface and multiple waves as well as by scattering from karst bodies.Therefore,the quality of the reflected seismic data is extremely low.Also,it is difficult to improve the signal to noise ratio(SNR)with conventional noise filtering methods.However,when the source depth is increased,the quality of the reflected waves can be improved.This is exactly what the RVSP method accomplishes.Besides,for the RVSP method,due to its particular geometry,the apparent velocities of the reflected waves and most interference waves are quite different,which can help to filter most noise to further improve the SNR of the reflected signals.In this study,a 3 D-RVSP exploration study using 8-hole joint acquisition was conducted in a typical karst landform.The results show that the 3 D-RVSP method can obtain higher quality seismic data for complex surface conditions that have large numbers of underground karst caves.Furthermore,multi-hole joint acquisition for 3 D-RVSP has higher data collection efficiency and better uniformity of underground coverage.Therefore,in this study,38 faults were accurately revealed and at high resolution based on the 3 D-RVSP imaging results.

Catalytic performance and synthesis of a Pt/graphene-TiO_2 catalyst using an environmentally friendly microwave-assisted solvothermal method

A Pt/graphene‐TiO2catalyst was prepared by a microwave‐assisted solvothermal method and was characterized by X‐ray diffraction,scanning electron microscopy,transmission electron microscopy,cyclic voltammetry,and linear sweep voltammetry.The cubic TiO2particles were approximately60nm in size and were distributed on the graphene sheets.The Pt nanoparticles were uniformly distributed between the TiO2particles and the graphene sheet.The catalyst exhibited a significant improvement in activity and stability towards the oxygen reduction reaction compared with Pt/C,which resulted from the high electronic conductivity of graphene and strong metal‐support interactions.

INTRANET监听检测原理与软件实现

Intranet的监听检测软件能有效的截获网络上的数据,但也对网络信息安全造成极大威胁。还必须采用各种反监听的检测措施以保护网络信息安全。监听实现包括数据包的捕获与过滤部分、监听检测部分、数据解码等部分。

First-principles study on properties and electron structure of CrB_2(0001) surface

Based on a first-principles density functional plane-wave ultrasoft pseudopotential method,the surface properties of two different types of terminated CrB2(0001)are calculated and compared,such as surface relaxation,surface energy and electricity structure.The results of surface relaxation show surface interlayer distance converges rapidly for both terminated CrB2(0001)when the number of the atoms layers reaches 9.Through analysis of charge density difference and partial density of states(PDOS),it can be concluded that CrB2(0001)models with B termination have smaller interface energy,stronger electronic interaction than another models and the form of termination is more stable.

Cluster analysis of the domain of microseismic event attributes for fl oor water inrush warning in the working face

Differences are found in the attributes of microseismic events caused by coal seam rupture,underground structure activation,and groundwater movement in coal mine production.Based on these differences,accurate classification and analysis of microseismic events are important for the water inrush warning of the coal mine working facefloor.Cluster analysis,which classifies samples according to data similarity,has remarkable advantages in nonlinear classification.A water inrush early warning method for coal minefloors is proposed in this paper.First,the short time average over long time average(STA/LTA)method is used to identify effective events from continuous microseismic records to realize the identification of microseismic events in coal mines.Then,ten attributes of microseismic events are extracted,and cluster analysis is conducted in the attribute domain to realize unsupervised classification of microseismic events.Clustering results of synthetic andfield data demonstrate the effectiveness of the proposed method.The analysis offield data clustering results shows that thefirst kind of events with time change rules is of considerable importance to the early warning of water inrush from the coal mine working facefloor.

Representations of Hom-Jacobi-Jordan Algebras

Some relationships between the representation of Hom-Jacobi-Jordan algebra and that of Jacobi-Jordan algebra are studied.Moreover,by using the notion ofαk-anti-derivation,a property theorem of multiplicative Hom-Jacobi-Jordan algebras is also given.

Visible-Light-Induced Selective Hydrocarboxylation of Alkynes with Formate

An efficient and sustainable protocol for regioselective hydrocarboxylation of alkynes to construct diverse propionic acid derivatives is disclosed.Under photoinduced conditions,the anti-Markovnikov hydrocarboxylation of alkynes was realized with CO_(2) radical anion in-situ generated from formate as both a carbonyl source and a reductant.The collaboration between photosensitizer and hydrogen atom transfer catalyst promoted the catalytic cycle to work smoothly,giving a broad substrate scope including terminal and internal alkynes.The Giese radical addition of CO_(2) radical anion to the C—C triple bond is the key step to initiate the reaction.

Base-Promoted Deconstructive Reaction of Exocyclic 1,3-Dicarbonyls for Accessing Hydrazonylated 1,n-Dicarbonyls and Its Biological Evaluation

A mild base-promoted three-component deconstructive functionalization of exocyclic 1,3-dicarbonyls with aryl diazonium tetrafluoroborates in the presence of alcohols is reported,enabling direct ring-opening of unstrained cyclic ring systems to produce six types of skeletally diverse hydrazonylated 1,n-diesters(e.g.,1,6-,1,7-1,8-,and 1,9-diesters)and 1,n-ketoesters(e.g.,1,6-and 1,7-ketoesters)with good yields,and the latter demonstrated complete(E)-selectivity.The methodology has the potential to be widely used throughout organic synthesis due to the use of easily accessible substrates with different substitution patterns,such as exocyclic 1,3-carbonyls and aryl diazonium tetrafluoroborates,and mild reaction conditions.Preliminary biological evaluation of some compounds,namely their inhibitory effect on human lung cancer cell MSTO-211H,was conducted.The results showed that compounds 3c and 3w exhibited significant inhibitory effects.

近距离突出煤层群水力冲孔卸压瓦斯抽采及效果评价研究

为高效评价近距离突出煤层群水力冲孔卸压瓦斯抽采效果,基于弹性力学、渗流力学和Klinkenberg效应等理论,建立了包含煤岩变形、瓦斯运移、孔隙率和渗透率演化数学方程的低透气性含瓦斯煤气固耦合模型,采用COMSOL Multiphysics数值模拟软件模拟分析了近距离突出煤层群水力冲孔钻孔周围煤体瓦斯压力与孔径之间的时空演化规律;基于质量守恒定律建立了近距离突出煤层群瓦斯抽采有效影响半径理论计算公式,并在贵州盘江煤电集团公司松河煤矿进行了工程试验及应用。得到以下结论:1)水力冲孔后,近距离煤层群各煤层的瓦斯抽采变化规律基本同步,水力冲孔的孔洞半径越大,影响半径越大,瓦斯抽采效果越好;2)现场试验结果显示,水力冲孔显著地改善了煤层瓦斯卸压抽采效果,且距离水力冲孔的孔洞越近,增透与卸压效果越好,瓦斯抽采体积分数和流量越大,考察孔对比结果确定了松河煤矿水力冲孔卸压抽采70 d的有效影响半径为4~5 m;3)将现场数据代入近距离突出煤层群瓦斯抽采有效影响半径理论公式中,得到的结果与数值模拟结果近似表明该理论公式的可行性。研究结果对近距离低渗透煤层群的瓦斯治理及效果评价具有良好的指导意义。

DGMI alleviates OGD/R-induced cell injury by regulating inflammatory and apoptosis signaling pathways

Diterpene ginkgolides meglumine injection(DGMI),a kind of Ginkgo biloba special extract injection,is now used for the treatment of ischemic stroke in convalescence.In the present study,we aimed to confirm whether DGMI could suppress inflammatory responses and apoptosis and explore the potential mechanisms underlying these effects.Cell viability and lactate dehydrogenase(LDH)release were measured by MTS and LDH assays after the cells were exposed to oxygen-glucose deprivation/reoxygenation(OGD/R).The extent of anti-apoptotic effect of DGMI was detected by flow cytometry using Annexin V-FITC/PI double staining assay kit.Pro-inflammatory cytokines,including TNF-α,IL-1β,IL-6 and IL-10,were quantified by a specific Bio-Plex ProTM Reagent Kit.Additionally,activities of TLR2/4,NF-κB p65,MAPK pathway and apoptosis-related proteins as well as cellular localization of NF-κB p65 were determined by Western blotting analysis and immunofluorescence staining,respectively.DGMI at 50μg/mL significantly increased the cell viability and decreased the secretion of IL-1β,IL-6,IL-10 and TNF-αin OGD/R-induced BV2 microglia cells.These effects were also confirmed by LDH assay and Annexin V-FITC/PI staining.Meanwhile,DGMI not only inhibited the protein expressions of TLR2,TLR4,MyD88,p-TAK1,p-IkBα,p-IKKβand Bak,but also decreased the cleaved caspase-3/caspase-3,Bax/Bcl-2 and cleaved PARP-1/PARP-1 ratio in OGD/R-induced BV2 microglia cells.Furthermore,OGD/R-enhanced p-JNK1/2 and p-p38 MAPK expressions and nuclear translocation of NF-κB p65 were also partially inhibited by DGMI.The present study showed that inflammatory responses were triggered in BV2 microglia cells activated by OGD/R,leading to the release of pro-inflammatory cytokines and apoptosis.DGMI suppressed the inflammatory response and apoptosis by regulating the TLR/MyD88/NF-κB signaling pathways and down-regulation of p-JNK1/2 and p-p38 MAPK activation.

Teasaponin induces reactive oxygen species-mediated mitochondrial dysfunction in Candida albicans

Candida albicans is the most prevalent commensal fungus and readily causes invasive fungal infection in immunocompromised individuals. Teasaponin(TS), a natural product generally regarded as safe, has been reported to inhibit filamentation of C. albicans. This study found that TS could exert moderate fungicidal activity against C. albicans, and the mode of action was further explored. The minimum fungicidal concentration(MFC) was determined by the broth microdilution method. The colony counting method was used to determine the time-killing curve of TS against C. albicans in every 2 h. The effect of TS on the content of intracellular reactive oxygen species(ROS) in C. albicans was analyzed by 2′,7′-dichlorofluorescin diacetate(DCFH-DA) staining, and the mitochondrial membrane potential(mtΔψ) was determined by rhodamine123(RH123) staining. An ATP assay kit was utilized to determine the intracellular ATP levels after TS treatment. Results showed that TS-induced ROS accumulation and mitochondrial dysfunction contributed to the death of C. albicans cells. Further research demonstrated that VC could reinforce the fungicidal ability of TS. On the contrary, VE could antagonize the function of TS against C. albicans, which might guide the clinical application of TS. The results preliminarily elucidated the potential mechanisms of TS against C. albicans and might provide a potential option for the treatment of clinical Candida.

Study on drug retention in menopausal women with sequential hormone therapy and tibolone

In the present study, we aimed to retrospectively analyze the medication prescriptions of menopausal women diagnosed with menopausal syndrome in our hospital from 2015 to 2018, and compare the retention rate of estrogen and progesterone sequential therapy and hormone continuous therapy in menopausal women. The rational drug management system of Ningbo Women and Children’s hospital was used to screen the prescriptions of menopausal syndrome in 4 years. After the age, year included in the study, and prescription cost were adjusted, Kaplan-Meier regression analysis was performed to compare the prescription retention rates of the two drug regimens. The distribution of the two HRT regimens in the 4 years showed an increasing trend year by year, and the age groups of the two HRT regimens were mainly distributed between 41 and 60 years old, accounting for 97.1% and 87.06%, respectively. The cost distribution for the other two HRT regimens was approximately the same. Compared with the two HRT regimens, the drug retention rate of hormone continuous regimens was higher than that of hormone sequential regimens within 4 years. Kaplan-Meier regression analysis showed that the trend was significant(Tarone-Ware, Chi-square value = 3.857, P = 0.050). This study found that the median retention time of HRT therapy in menopausal women in our hospital was about half a year, which was significantly lower than that reported in previous studies of 1 year or longer. In addition, the present study found that compared with Femoston, the tibolone regimen significantly increased retention time in the treatment of menopausal syndrome.

教师的课堂语言修养

课堂教学是教学的主要环节,教师通过自己的课堂语言向学生讲授本课程知识,带给学生综合的、多方位、多层面的教育信息,并且通过语言渠道与学生开展情感交流,实现课堂教学的育人功能。因此,教师的语言修养水平和表达能力就在很大程度上决定和影响着教师的教学水平和教学效果。那么,教师应当从哪些方面提高自己的课堂语言修养呢? 一、语言表达 课堂教学首先要求教学内容的科学性、概念的准确性和逻辑的严密性。因此,教师的课堂语言必须首先做到语义鲜明、准确、逻辑性强。要做到这一点,就必须认真备课,吃透教学内容,在深刻理解的基础上,用自己的语言深入浅出地讲给学生。对内容越熟悉,理解越深。

Interface Characteristics and Evolution Mechanism of W/CuCrZr in Hot Melt Explosion Welding

Explosion welding was carried out on the basis of vacuum hot melt W/CuCrZr composite plate.Metallurgical microscope,scanning electron microscope and energy dispersive X-ray spectroscope were used to observe the microscopic morphology of the bonding interface.At the same time,combined with finite element calculations,the evolution mechanism of the interface of the hot melt explosion welded W/CuCrZr composite plate was explored.The results show that the interface bonding of the hot melt explosion welded W/CuCrZr composite plate is good and there is a cross-melting zone with 3–8μm in thickness,but cracks are developed on the W side.The numerical simulation reproduces the changes of pressure,stress,strain and internal energy at the bonding interface in the process of hot melt explosion welding.The location of the crack generated in the experiment coincides with the high stress position calculated by numerical simulation.The high pressure and high temperature near the hot melt explosion welding interface further promote the bonding of the interface.