Geometrical Structure of Two-Dimensional Crystals with Non-Constant Dislocation Density

We outline mathematical methods which seem to be necessary in order to discuss crystal structures with non-constant dislocation density tensor (ddt) in some generality. It is known that, if the ddt is constant (in space), then material points can be identified with elements of a certain Lie group, with group operation determined in terms of the ddt—the dimension of the Lie group equals that of the ambient space in which the body resides, in that case. When the ddt is non-constant, there is also a relevant Lie group (given technical assumptions), but the dimension of the group is strictly greater than that of the ambient space. The group acts on the set of material points, and there is a non-trivial isotropy group associated with the group action. We introduce and discuss the requisite mathematical apparatus in the context of Davini’s model of defective crystals, and focus on a particular case where the ddt is such that a three dimensional Lie group acts on a two dimensional crystal state—this allows us to construct corresponding discrete structures too.     

胭脂鱼消化道黏膜上皮扫描电镜观察

应用扫描电镜观察了胭脂鱼食管、胃、前肠、中肠和后肠黏膜上皮表面细微结构。发现消化道黏膜皱褶形态差异显著,胃黏膜上皮细胞表面有微绒毛,分布密集,但在部分区域有成簇的壁细胞,呈柱状;肠黏膜上皮表面的微绒毛似苔藓状覆盖在细胞的表面,扫描电镜观察发现前肠上皮细胞分泌孔较多,微绒毛密集且高度参差不齐;中肠上皮细胞分泌孔明显减少,微绒毛比前肠密且平整;后肠分泌孔孔径变小,数量最少,且微绒毛较稀疏,表面最平滑,细胞呈梭形环绕,形成杯状结构。亚成体鱼与幼鱼的消化道黏膜上皮结构相似,但其分泌孔孔径和分泌孔密度有差异,亚成体鱼的分泌孔孔径和分泌孔密度更大,说明亚成体鱼消化能力强于幼鱼。 更多还原     

共面对称条件下Mg原子(e,2e)反应的三重微分截面的计算

采用修正的扭曲波玻恩近似(DWBA)方法,本文计算了共面对称几何条件下电子碰撞Mg(3s2) 原子(e,2e)反应的三重微分截面.理论方法通过引入Gamow因子来表示(e,2e)反应的后碰撞相互作用(PCI).将计算结果与实验结果及标准DWBA计算结果进行了比较,发现PCI效应起着重要的作用.     

1-苯并噻唑基-吡唑啉类荧光化合物的合成及其荧光光谱

合成了几种苯并噻唑基 -吡唑啉类化合物 ,经红外吸收光谱和荧光发射光谱测定 ,此类化合物具有一定的荧光性 ,其荧光强度的大小与衍生物中不同的取代基有关。     

Signatures of non locality for short-ranged wetting at curved substrates

The binding potential for wetting near planes, spheres, and cylinders in systems with short-ranged forces is shown to have a universal geometrical structure. This arises from the nonlocal nature of the interfacial interactions and is exactly described by a recently proposed binding potential functional, which provides a systematic framework for studying wetting at arbitrarily shaped substrates. The corrections to the equilibrium wetting layer thickness induced by nonlocality are comparable to those arising from a Tolman length and lead to diverging terms in the total mass adsorption.     

Impact of reductive cleavage of an intramolecular disulfide bond containing cationic gemini surfactant in monolayers and bilayers

The properties of a novel disulfide-bond-containing gemini surfactant bis[N,N-dimethyl-N-hexadecyl-N-(2-mercaptoethyl)ammonium bromide] disulfide (DSP) were studied using a Langmuir balance, supported monolayers, differential scanning calorimetry, giant vesicles, and LUVs. In 150 mM NaCl the cmc for DSP was 7.5 microM whereas that of the monomer N,N-dimethyl-N-hexadecyl-N-(2-mercaptoethyl)ammonium bromide (MSP) was 12.1 microM. Both surfactants exhibited single endotherms upon DSC, with peak temperatures Tm at 21.7 and 20.1 degrees C for DSP and MSP, respectively. The endotherm for MSP was significantly broader indicating less cooperative melting. Both in monolayers and in vesicles reductive cleavage of the disulfide bond of DSP could be obtained by glutathione (GSH). For Langmuir films of DSP the addition of GSH into the subphase led to a decrease in surface pressure pi as well as surface dipole potential psi. Although the cleavage by GSH was significantly slower in the presence of a charge saturating concentration of DNA, it did not prevent the reaction. The resulting monomers detached from supported monolayers, leading to loss of affinity of the surface for DNA. Disruption of giant vesicles containing DSP within approximately 30 s following a local injection of GSH was observed, revealing membrane destabilization.     

一种紫外-可见光谱法检测水质COD的浊度影响实验研究

消除浊度影响是直接光谱法检测水质COD的关键技术问题。此源于紫外-可见光谱法检测水质参数的关键依赖于化学计量法所建立的准确的水质参数分析模型,而浊度是影响其建模的一个重要参数。为此,选取福尔马肼浊度液和邻苯二甲酸氢钾标准溶液,开展了紫外-可见吸收光谱法检测水质COD的浊度影响实验研究,获得了选定溶液在245,300,360和560 nm几个特征波长点的吸光度随浊度变化的最小二乘法拟合曲线,分析了吸光度随浊度的变化规律。研究结果表明,在240～380 nm的紫外光谱段,由于引起浊度的颗粒物对有机物产生了吸附,致使浊度对水样的紫外光谱影响较为复杂;在380～780 nm的可见光谱区域,浊度对光谱的影响则是随着波长的增大而减弱。基于此,开展了多元散射校正法对受浊度影响的水样光谱进行校正试验。对某溪水水样的紫外-可见吸收光谱进行多元散射校正,通过处理前后光谱对比表明,浊度引起各个波长点的基线偏移都得到了有效的校正,而在紫外区域特征并未减弱。接着对选取的三种液体的紫外-可见吸收光谱进行多元散射校正,实验结果表明：该方法可在不影响水样紫外-可见吸收光谱特征的前提下对其吸收曲线进行有效的校正,这不仅提高了光谱法检测水质COD的信噪比,而且还为化学计量法建立准确、有效的水质检测COD分析模型进行数据预处理提供了一种新途径。     

Wetting of a plane with a narrow solvophobic stripe

ABSTRACT

We present a numerical study of a simple density functional theory model of fluid adsorption occurring on a planar wall decorated with a narrow deep stripe of a weaker adsorbing (relatively solvophobic) material, where wall-fluid and fluid-fluid intermolecular forces are considered to be dispersive. Both the stripe and outer substrate exhibit first-order wetting transitions with the wetting temperature of the stripe lying above that of the outer material. This geometry leads to a rich phase diagram due to the interplay between the pre-wetting transition of the outer substrate and an unbending transition corresponding to the local evaporation of liquid near the stripe. Depending on the width of the stripe, the line of unbending transitions merges with the pre-wetting line inducing a two-dimensional wetting transition occurring across the substrate. In turn, this leads to the continuous pre-drying of the thick pre-wetting film as the pre-wetting line is approached from above. Interestingly we find that the merging of the unbending and pre-wetting lines occurs even for the widest stripes considered. This contrasts markedly with the scenario where the outer material has the higher wetting temperature, for which the merging of the unbending and pre-wetting lines only occurs for very narrow stripes.     

Four-quasiparticle high-K band in 130Ce

High-spin states have been populated in ¹³⁰Ce, using the ¹⁰⁰Mo(³⁴S, 4n??) reaction at 155 MeV. A new strongly coupled structure has been found and is interpreted as based on a mixed neutron-proton high-K four-quasiparticle configuration.     

二维流场、热结构松耦合模拟研究

本文针对轴对称型飞行器前缘部位,采用松耦合方法,开展了二维高超声速流固界面的热耦合计算。满足非稳态N-S方程的外部流场和内部非稳态热传导均采用商用软件FLUENT进行计算。通过对相同时刻,不同松耦合推进时间步长引起的壁面热流密度、壁面温度、表面传热系数的差异对比,得出了松耦合推进时间对以上参数的影响规律,这对有效实施松耦合方法进行高超声速飞行器模拟具有积极意义。