初级视皮层神经元响应反应与撤反应的朝向选择性

朝向选择性是初级视皮层(17区或V1)神经元的基本性质,在图形感知中起着关键作用.同时这些神经元对于持续时间大于100 ms的视觉刺激具有清晰的响应反应(Onset responses)和撤反应(Offset responses).以往的研究只关注响应反应的朝向选择性,而忽视了对撤反应的朝向选择性研究.我们比较了响应与撤反应的朝向调谐性质,大多数细胞的撤反应与响应反应基本上具有相似的最优朝向,而撤反应的朝向调谐宽度有窄于响应反应的趋势,撤反应的最优延迟普遍滞后于响应反应的最优延迟.撤反应的朝向选择性略强于响应反应和具有显著长的反应延迟提示,皮层内的反馈输入可能在形成撤反应的朝向选择性中起着作用.本研究揭示了撤反应的朝向选择性在刺激朝向的连续表征和主体在形状知觉的后期对朝向的精细区分中起着作用.

桥墩长细比对地震反应谱响应的影响分析

采用ANSYS有限元分析程序,对某连续刚构桥进行了不同桥墩长细比情况下地震反应谱响应分析。由于改变长细比的方法不同,模型分为2组,第1组中改变桥墩沿纵桥向长度,第2组中改变桥墩高度,地震反应谱采用《公路桥梁抗震设计细则》(JTG/TB02-01—2008)中规定的设计加速度反应谱。研究结果表明:桥墩的长细比对连续刚构桥梁地震反应影响显著;随桥墩长细比增大,地震作用时,墩顶和墩底的受力将减小,但当桥墩长细比达到某一数值时,再增大长细比,桥墩受力变化将不再显著。

堆外核测量系统裂变电离室线性响应研究

为满足先进反应堆堆外核测量系统中间量程测量通道灵敏度高、探测器灵敏区长、反应堆线性响应好的需求,采用多支灵敏区长度具有一定比例关系、同时机械结构完全相同的裂变电离室,进行热中子灵敏度标定和反应堆线性响应研究,以为核电厂实际所需长灵敏区裂变电离室提供一种在现有试验堆条件下进行其核性能试验的方法。通过测量不同灵敏区长度的裂变电离室热中子灵敏度和反应堆高中字注量率下的线性响应,对其热中子灵敏度随灵敏区长度的线性变化和反应堆线性响应进行试验验证。测量结果表明,裂变电离室热中子灵敏度随灵敏区长度呈线性关系,且在反应堆热中子注量率1.23×10^(2)~3.10×10^(10)nv(1nv=1n·cm^(-2)·s^(-1))范围内进行计数率模式和MSV模式线性拟合,裂变电离室最大线性度为-1.23%。

空间小净距交叉隧道动力响应振动台试验研究

为研究空间小净距交叉隧道在地震荷载作用下的动力响应,开展了相似比为1∶50的振动台模型试验,设计并加载了5种工况水平向El-Centro地震波,通过采集的试验数据对隧道动应变响应进行了分析,并对交叉段及非交叉段围岩的加速度响应进行了对比研究,在此基础上使用反应谱理论对其动力特性与地震动之间的关系进行探讨。试验结果表明:上跨隧道的应变峰值均大于下穿隧道,同时上跨隧道的存在及围岩的挤密效应减弱了地震波对于下穿隧道的冲击作用;地震荷载作用下空间交叉隧道的动力响应具有一定的“滞后性”,上跨隧道的震害破坏出现时间较早且更为严重;围岩内部各测点的加速度放大效应都沿高程方向表现出显著的峰值特征,非交叉段的加速度响应在靠近上跨隧道拱顶处最为强烈,而交叉段却出现在靠近下穿隧道拱顶处;坡体各测点位移反应谱的幅值随输入地震波幅值的增大而逐渐增大,且卓越周期也随之增大,即卓越频率逐渐减小;弱震(0.1g)作用下,短周期(0.5~1.5 s)内反应谱曲线具有显著的峰值特征,而强震(0.6g)作用下,长周期(3.0~5.0 s)内反应谱曲线沿高程具有明显的放大效应。

墩高对桥梁动力响应的影响分析

以某三跨连续钢箱梁工程为背景,采用SAP2000建立有限元模型,对不同墩高下梁桥的动力特性及反应谱响应进行研究。设计加速度反应谱依照《公路桥梁抗震设计规范》(JTG/T 2231-01-2020)中规定。计算分析对比表明:墩高对结构的自振周期影响较大;地震反应谱分析时,随着墩高的不断提升,墩顶漂移比(即墩顶位移与墩高的比值)及墩底弯矩均不断加大。故选取一个合适的墩高,对于桥梁抗震十分重要。

Characteristics of resistivity log response of oil layers under polymer flooding

Resistivity log responses are different when the oil layers is filled by a polymer solution or water and it seriously affects the log interpretation of the water flooded layer. In this paper, we first analyze the electrical properties of the polymer solution. Then, according to the different processes for polymer flooding the reservoir, we perform rock resistivity experiments and analyze the rock resistivity variations in different displacement phases. We also compare the resistivity log responses of oil layers filled with the polymer solution to those filled with water. The results show that when displacing the oil-bearing core by different polymers, the resistivity changes monotonously decrease and show either ＂W＂ type or ＂S＂ type. The resistivity log responses are weak when displacing water and there is no flooded show if the oil layer is injected by a fresh water polymer solution. If the oil layer is injected by a sewage polymer solution, the resistivity log response has similar characteristic as a polluted water flooded layer.

Analysis of the Effects of Slope Geometry on the Dynamic Response of a Near-field Mountain from the Wenchuan Earthquake

Fourier spectra and acceleration response spectra of near-field acceleration records of the 2008 Wenchuan Earthquake have been calculated.Relative fundamental frequencies(or predominant periods) were characterized.Then,the natural frequencies of a range of slopes with different geometric characteristics,such as height,slope ratio,and pattern,were analyzed.The seismic responses of the slopes were compared,and the variability of seismic response with the above geometric elements was found.Results show that if slope height increases,and provided that other conditions are unchanged,the natural frequency of the first mode of a doublesurface slope will change as a power law.However,natural frequencies will diminish(based on a parabolic function) as the slope angle becomes large.Both the surface pattern and the number of surfaces on a slope can have a great impact on the seismic response of the slope.Moreover,within a certain range of slope heights or angles,either height or angle will also greatly influence the variability of the seismic response.The results of this research will be helpful to understanding seismic dynamic response features and explaining the ways that slope stability can be affected by earthquakes.

Green and efficient epoxidation of methyl oleate over hierarchical TS-1

The epoxidation of methyl oleate(MO)was conducted in the presence of aqueous H2O2 as the oxidant and hierarchical TS-1(HTS-1)as the catalyst;the catalyst was synthesized using polyquaternium-6 as the mesopore template.The effects of various parameters,i.e.,H2O2/C=C molar ratio,oxidant concentration,amount of the catalyst,reaction temperature,and time,were systematically studied.Furthermore,response surface methodology(RSM)was used to optimize the conditions to maximize the yield of epoxy MO and to evaluate the significance and interplay of the factors affecting the epoxy MO production.The H2O2/C=C molar ratio and catalyst amount were the determining factors for MO epoxidation,wherein the maximum yield of epoxy MO reached 94.9%over HTS-1 under the optimal conditions.

Application of response surface methodology for optimization of purge gas recycling to an industrial reactor for conversion of CO_2 to methanol

Nowadays, by the increasing attention to environment and high rate of fuel production, recycling of purge gas as reactant to a reactor is highly considered. In this study, it is proposed that the purge gases of methanol production unit, which are approximately15.018 t·h^(-1) in the largest methanol production complexes in the world, can be recycled to the reactor and utilized for increasing the production rate. Purge gas streams contain 63% hydrogen,20% carbon monoxide and carbon dioxide as reactants and 17% nitrogen and methane as inert. The recycling effect of beneficial components on methanol production rate has been investigated in this study. Simulation results show that methanol production enhances by recycling just hydrogen, carbon dioxide and carbon monoxide which is an effective configuration among the others. It is named as Desired Recycle Configuration(DRC) in this study. The optimum fraction of returning purge gas is calculated via one dimensional modeling of process and Response Surface Methodology(RSM) is applied to maximize the methanol flow rate and minimize the carbon dioxide flow rate. Simulation results illustrate that methanol flow rate increases by 0.106% in DRC compared to Conventional Recycle Configuration(CRC) which therefore shows the superiority of applying DRC to CRC.

Influence of seismic input on response of Baihetan arch dam

The dynamic responses of the arch dam including dam-foundation-storage capacity of water system,using two different earthquake input models,i.e.viscous-spring artificial boundary(AB)condition and massless foundation(MF),were studied and analyzed for the 269 m high Baihetan arch dam under construction in China.By using different input models,the stress and opening of contraction joints(OCJs)of arch dam under strong shock were taken into consideration.The results show that the earthquake input models have slight influence on the responses including earthquake stresses and openings of contraction joints in different extents.

Gene cloning and induced expression pattern of IRF4 and IRF10 in the Asian swamp eel(Monopterus albus)

The Asian swamp eel （Monopterus albus） is one of the most economically important freshwater fish in East Asia, but data on the immune genes of M. albus are scarce compared to other commercially important fish. A better understanding of the eel＇s immune responses may help in developing strategies for disease management, potentially improving yields and mitigating losses. In mammals, interferon regulatory factors （IRFs） play a vital role in both the innate and adaptive immune system; though among teleosts IRF4 and IRFIO have seldom been studied. In this study, we characterized IRF4 and IRFIO from M. albus （malRF4 and malRFlO） and found that malRF4 cDNA consists of 1 716 nucleotides encoding a 451 amino acid （aa） protein, while malRFlO consists of 1 744 nucleotides including an open reading frame （ORF） of 1 236 nt encoding 411 aa. The malRFlO gene was constitutively expressed at high levels in a variety of tissues, while malRF4 showed a very limited expression pattern. Expression of malRF4 and malRFlO in head kidney, and spleen tissues was significantly up-regulated from 12 h to 48 h post-stimulation with polyinosinic： polycytidylic acid （poly I：C）, lipopolysaccharide （LPS） and a common pathogenic bacteria Aeromonas hydrophila. These results suggest that IRF4 and IRF10 play roles in immune responses to both viral and bacterial infections in M. albus.

The Design and Control of Distillation Column with Side Reactors for Chlorobenzene Production

The distillation column with side reactors (SRC) can overcome the temperature/pressure mismatch in the traditional reactive distillation, the column operates at temperature/pressure favorable for vapor-liquid separation, while the reactors operate at temperatures/pressures favorable for reaction kinetics. According to the smooth operation and automatic control problem of the distillation column with side reactors (SRC), the design, simulation calculation and dynamic control of the SCR process for chlorobenzene production are discussed in the paper. Firstly, the mechanism models, the integrated structure optimal design and process simulation systems are established, respectively. And then multivariable control schemes are designed, the controllability of SRC process based on the optimal steady-state integrated structure is explored. The dynamic response performances of closed-loop system against several disturbances are discussed to verify the effectiveness of control schemes for the SRC process. The simulating results show that the control structure using conventional control strategies can effectively overcome feeding disturbances in a specific range.

Thermosensitive Poly(N-isopropylacrylamide-co-acrylonitrile) Hydrogels with Rapid Response

Acrylonitrile (AN) was copolymerized with N-isopropylacrylamide (NIPA) to synthesize thermosensitive hy-drogels, and the on-off switch behavior of poly(NIPA-co-AN) hydrogels with different fraction of hydrophobic compo-nent (AN) was investigated. It is found that the lower critical solution temperature (LCST), the swelling ratio at certain temperature and the reswelling rate of poly(NIPA-co-AN) hydrogels decreased as AN unit fraction in copolymers in-creased. In order to improve the responsive rate of poly(NIPA-co-AN) hydrogels, they were further treated by surface crosslinking using N, N′-methylene bisacrylamide (BIS) as a crosslinking agent. The swelling and deswelling behaviors of these copolymers were compared with those of the untreated hydrogels. The results indicated that the responsive rate of poly(NIPA-co-AN) hydrogel was improved by surface crosslinking. The resulting hydrogels bearing cyano groups with fast response have potential applications in the field of drug-controlled release and immobilization of biomolecules.

Synthesis of Vanillin 1, 2-Propylene Glycol Acetal Catalyzed by H3PMo6W6O40·nH2O

Vanillin 1, 2-propylene glycol acetal was synthesized from vanillin and 1, 2-propylene glycol using H3PMo6W6O40·nH2O as catalyst, The factors influencing the synthesis were discussed and the better reaction conditions were found as follows： The amount of vanillin was 3.8 g, the molar ratio of vanillin was 1, 2-propylene glycol 1.0 to 2.4, the amount of catalyst was 1.6% in proportion to the total reacting materials, the volume ofcyclohexane as the water-carrying agent 4 mL, the refluxing time was 2 h at 88-96℃ and thus the product yield reached over 87%. The results show that the catalyst＇s activity is high and the reaction time is short.

Cellular Response to Irradiation

To explore the nonlinear activities of the cellular signaling system composed of one transcriptional arm and one protein-interaction arm, we use an irradiation-response module to study the dynamics of stochastic interactions. It is shown that the oscillatory behavior could be described in a unified way when the radiation-derived signal and noise are incorporated.

Fundamental Characteristics of Reduction System for Seismic Response using Friction Force

A new device of reduction for seismic response using friction force was developed. In this paper, fundamental characteristics of reduction system for seismic response using this device were investigated by excitation experiment using artificial seismic waves. The peak acceleration amplitude on this system has decreased to about 50-90% over the input waves. Although a spectral peak around the frequency of 0.5Hz that is the natural period of this system was identified, the value of a spectral peak was decreased using bearings with the high friction force. This device is useful for reduction of seismic response.

Simplified Analysis of the Effect of Soil Liquefaction on the Earthquake Pile Response

The time-history response of a structure-pile system during soil liquefaction is highly complicated and several analytical methods have been proposed through the accuracy verification based on the comparison with the experimental works. However, the analytical methods with higher accuracy often require large computational loads and are not necessarily preferred in the actual design practice. On the other hand, while the response spectrum method is not accurate compared to the aforementioned methods, it can provide useful design guidelines in the preliminary stage for structure-pile systems under soil liquefaction with acceptable accuracy. In this paper, the previously proposed response spectrum method for a structure-pile-soil system is used where the effect of soil liquefaction is taken into account by introducing the so-called p-multiplier method. It is shown that, while in the case of inner partial liquefaction with a non-liquefied layer at the top, the demand on the pile moment is large due to the inertial effect of that non-liquefied layer at the top, in the case of overall liquefaction near the ground surface, the demand is smaller than the case of inner partial liquefaction.

Tall building configuration effects on their response to earthquake loading

This paper studies and analyzes the response and behavior of regular and irregular building structures in earthquake zones. The non-linear dynamic response of tall buildings structures were obtained using five simulated models, which were subjected to UBC code dynamic and static equivalent earthquake loads. The maximum response of the structural models were computed and analyzed in order to verify the effects of building configuration on drift results. Drift results agreed with codes recommendations regarding building configuration and showed that regular buildings performance in resisting earthquake forces is better than that of irregular buildings.

Influence of site conditions on ground motion at far field loess sites during strong earthquake

Loess is widely distributed in China and the Loess Plateau is one of the major areas where strong earthquakes often take place. The seismic amplification effects were discovered in the Plateau during the Wenchuan Ms8.0 earthquake and some other strong events. Based on earth tremor observation, borehole exploration and site seismic response analysis, the site effects of topography of Loess Yuan on ground motion were investigated in details. The earth tremor investigation shows that predominant frequencies at the bottom sites of Loess Yuan are greater than those at the top obviously. The sites seismic response analysis shows that the Loess Yuan may amplify peak ground acceleration (PGA) by 1.44 2.0 times. Therefore, site effects of mountains and loess topography on ground motion should be taken account into in seismic design in loess regions.

Helicoidal shell response to earthquake loads

This paper studies and analyzes the response of helical stairs as helicoidal shells in earthquake zones. The response of helical stairs under gravity loads was analyzed by both the membrane theory and finite element methods. The non-linear response of helical stairs, when subjected to UBC （Uniform Building Code） dynamic and static equivalent earthquake loads, were obtained using finite element models. These responses were compiled and analyzed in order to draw recommendations for the preliminary design of helical stairs in earthquake zones. The analysis of the results obtained showed that helical stairs are stiffer and lighter than regular ones.