P(NVP-co--βHPAT)/CS半互穿网络凝胶的合成与环境响应特性

以壳聚糖(CS),N-乙烯基吡咯烷酮(NVP)和丙烯酸β-羟基丙酯(β-HPAT)为原料,合成了半互穿网络(Semi-IPN)水凝胶P(NVP-co-β-HPAT)/CS(简称Semi-IPNH),其结构经FT-IR,TG和SEM表征.对Semi-IPNH的温度与pH敏感环境响应特性进行了研究,考察了温度、pH值、离子强度以及单体配比等对其溶胀度的影响.结果表明,Semi-IPNH具有较敏锐的温度及pH敏感特性;在离子强度小于2.0 mol·L-1时,对Semi-IPNH的溶胀行为影响不明显;随着NVP含量的增大,凝胶的溶胀率增大.在20 ℃或45 ℃的去离子水及pH 3.0或pH 8.0的柠檬酸/磷酸氢二钠缓冲溶液中,Semi-IPNH的溶胀-收缩具有可逆性.     

一种氧化海藻酸钠基温敏凝胶的制备与性能

合成出一种具有温敏特性的多官能团的大分子聚(N-异丙基丙烯酰胺-丙烯酸甲酯-丙烯酰肼)(PNMH),用它交联氧化的海藻酸钠(OSA),得到可生物降解的温敏凝胶PNMH-OSA.分别以凝胶的透光率随温度变化和凝胶在磷酸盐缓冲液(PBS)中的溶胀比随时间变化来考察凝胶的温敏性能和降解性能,并采用傅立叶变换红外光谱(FTIR)和激光共焦拉曼光谱(LCRS)对样品进行了表征.结果表明,PNMH-OSA凝胶是通过PNMH上的—NHNH2和OSA上的—CHO反应生成C N键而形成的化学交联凝胶;随着凝胶中PNMH量的增加,PNMH-OSA凝胶的温敏性增强,降解时间延长;温敏组分的含量对PNMH-OSA凝胶的溶胀和降解性能与温度的关系影响显著.     

交错电极介质阻挡放电等离子体弦向特性的研究

在绝缘材料两侧交错布置电极的方式是航空领域所使用的等离子体激励器与众不同之处,因此航空等离子体激励器生成的等离子体具有沿弦向变化特点。利用光谱仪、红外热像仪、激光诱导荧光系统(LIF)对交错电极介质阻挡放电等离子体弦向特性进行了实验研究,并对介质阻挡放电等离子体流动控制机理作了初步的探讨。实验中发现等离子体发光强度和温度沿弦向的分布基本符合高斯分布;发射等离子体光谱强度随着电压升高而增大;等离子体弦向温度随激励电压的增大而增加;通过LIF系统直接检测到放电产生的NO。通过数值模拟得到电极附近的电势和电场强度分布进而对实验现象作了初步的解释,并在以上实验的基础上,将等离子体流动控制机理归纳为撞击效应、温升效应和化学反应效应。     

Comments on Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD

The explicit compact difference scheme,proposed in Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD by Lin et al.,published in Applied Mathematics and Mechanics (English Edition),2007,28(7),943-953,has the same performance as the conventional finite difference schemes.It is just another expression of the conventional finite difference schemes. The proposed expression does not have the advantages of a compact difference scheme. Nonetheless,we can more easily obtain and implement compared with the conventional expression in which the coefficients can only be obtained by solving equations,especially for higher accurate schemes.     

ONSET CONDITION OF STRAIN LOCALIZATION IN MATRIX OF SATURATED POROUS MEDIA

Introduction Strainlocalizationofgeomaterialsisoneofmostpopularfailuretypesinnature,which canbeshowedaslandslidesandmudflowsinmountainousareasunderincessantorheavy raining,especiallythevegetationisseverelydamagedbywoodsharvest;pipingeffect,a typeoflocalfa…     

Conceptional design of a heavy ion linac injector for HIRFL-CSRm

A room temperature heavy ion linac has been proposed as a new injector of the main Cooler Storage Ring(CSRm) at the Heavy Ion Research Facility in Lanzhou(HIRFL), which is expected to improve the performance of HIRFL. The linac injector can supply heavy ions with a maximum mass to charge ratio of 7 and an injection kinetic energy of 7.272 MeV/u for CSRm; the pulsed beam intensity is 3 emA with the duty factor of 3%. Compared with the present cyclotron injector, the Sector Focusing Cyclotron(SFC), the beam current from linac can be improved by 10–100 times. As the pre-accelerator of the linac, the 108.48 MHz 4-rod Radio Frequency Quadrupole(RFQ) accelerates the ion beam from 4 keV/u to 300 keV/u, which achieves the transmission efficiency of 95.3% with a 3.07 m long vane.The phase advance has been taken into account in the analysis of the error tolerance, and parametric resonances have been carefully avoided by adjusting the structure parameters. Kombinierte Null Grad Struktur Interdigital H-mode Drift Tube Linacs(KONUS IH-DTLs), which follow the RFQ, accelerate ions up to the energy of 7.272 MeV/u for CSRm. The resonance frequency is 108.48 MHz for the first two cavities and 216.96 MHz for the last 5 Drift Tube Linacs(DTLs). The maximum accelerating gradient can reach 4.95 MV/m in a DTL section with the length of17.066 m, and the total pulsed RF power is 2.8 MW. A new strategy, for the determination of resonance frequency,RFQ vane voltage and DTL effective accelerating voltage, is described in detail. The beam dynamics design of the linac will be presented in this paper.     

一种基于相关分析的局域最小二乘支持向量机小尺度网络流量预测算法

本文分析了网络流量数据的特性,针对传统预测算法在预测网络流量时的缺陷提出了一种基于相关分析的相关局域最小二乘支持向量机(LSSVM)预测算法.算法在对训练数据重构相空间后,利用相关分析同时从距离相关和时间相关的训练样本中选择最优的训练子集,结合自适应参数优化的LSSVM预测模型对小尺度网络流量进行预测.通过选用实际情况下的网络流量数据对算法进行测试验证,结果显示本文所提算法不仅优于传统的全局预测算法,同时也优于各种改进的局域预测算法.算法不仅在预测精度上取得大幅的性能提升,同时能够通过留一交叉验证法在预测之前就完成预测模型和训练子集的优化.     

三聚氰酸钴配合物的合成、晶体结构及荧光性质

本文合成了一个新的配合物Co(H2CA)2(H2O)2(H3CA=三聚氰酸),并通过元素分析、红外、荧光和单晶X-Ray射线进行了表征。标题化合物属于三斜晶系,P1空间群,a=0.503 83(7)nm,b=0.699 82(10)nm,c=0.911 08(13)nm,α=90.107(2)°,β=98.032(2)°,γ=110.788(2)°,V=0.296 92(7)nm3,Z=1,R=0.038 2。在配合物中,Co(Ⅱ)离子与三聚氰酸配体上的N原子,配位水的O原子配位,形成规则的平面正方形配位构型。相邻的2个Co(Ⅱ)平面四边形单元通过配体三聚氰酸上的氢键形成三维网状结构。室温荧光光谱测定表明该化合物在420 nm处有强的荧光发射。     

防晒BB霜的配方研究

介绍了BB霜的现状和不足,讨论了防晒BB霜配方的设计原理、配方和生产工艺。配方设计原理中重点介绍UVA和UVB如何搭配使用,丁基甲氧基二苯甲酰基甲烷、水杨酸乙基己酯、甲氧基肉桂酸乙基己酯、纳米级钛白粉(二氧化钛)是常用的化学防晒剂和物理防晒剂。     

Particle-in-cell mode beam dynamics simulation of the low energy beam transport for the SSC-linac injector

A new SSC-linac system (injector into separated sector cyclotron) is being designed in the HIRFL (heavy ion research facility of Lanzhou). As part of SSC-Linac, the LEBT (low energy beam transport) consists of seven solenoids, four quadrupoles, a bending magnet and an extra multi-harmonic buncher. The total length of this segment is about 7 meters. The beam dynamics in this LEBT has been studied using three-dimensional PIC (particle-in-cell) code BEAMPATH. The simulation results show that the continuous beam from the ion source is first well analyzed by a charge-to-mass selection system, and the beam of the selected charge-to-mass ratio is then efficiently pre-bunched by a multi-harmonic buncher and optimally matched into the RFQ (radio frequency quadrupole) for further acceleration. The principles and effects of the solenoid collimation channel are discussed, and it could limit the beam emittance by changing the aperture size.