皂苷、皂苷元分子聚集相行为的原子力显微镜研究

用原子力显微镜检测了不同浓度下皂苷和皂苷元的分子聚集相行为。实验表明,当浓度为1.0×10-5mol/L时,皂苷形成分散较均匀的小片段结构,表现为皂苷分子的聚集体结构;而皂苷元由多个分子连接形成聚集体结构,与皂苷相比高度起伏较低,链的长度较长。浓度为1.0×10-4mol/L时,皂苷出现了不规则片层与小片段共存结构;皂苷元却形成多孔的网状结构。当浓度增大到1.0×10-3mol/L时,皂苷小分子紧密聚集、分布在云母表面;皂苷元则形成紧密聚集的大片层多孔结构。结构分析表明,分子官能团的属性对于皂苷和皂苷元分子形成的不同结构起到了关键作用,分子骨架中的糖链阻碍皂苷形成大片层结构,而皂苷元由于分子骨架中羟基间氢键相连接,易于形成大的片层结构。

碘化铯晶体中Ph^(2+)基聚集相的发光性质

掺铅的碘化铯（Pb：CsI）晶体在400℃空气中进行热处理可以在晶体中诱导产生发光中心，这些发光中心的激发谱与CS－Pb-I体系中一系列化合物的激子吸收谱相吻合．它们被认为是由该晶体在退火过程中所形成的CsPbI3、Cs4PbI6等聚集相产生的．测量了10～30K温度范围内分别在410nm和360nm波长激发下Ph：CsI的发射谱，观察到各发射谱的相对强度随退火时间而变化，这表明在400℃退火温度下晶体中各类Cs－Ph－I聚集相的形成和转化已十分活跃．

黏度对油气混输泵内气相和泄漏涡分布的影响

为了更准确地探究油气混输泵在高黏度条件下输送介质时,其流道内常常存在的泄漏涡、分离涡等这些涡流的特性,文中选用欧拉-欧拉非均相流模型对油气混输泵内气相分布以及涡分布进行分析,并使用刚性旋转涡量表征涡旋强度.研究表明:在混输泵叶轮流道内,气相的存在较大地影响了叶片表面流线的分布规律.偏设计工况下,当黏度较小时气相主要集中分布在压力面后半段,当黏度较大时气相在压力面后段分布较少.不同工况下泄漏涡的分布规律都与气相分布吻合度较高,在偏设计工况下,其气相在流道尾部的聚集度和黏度成正比,但是在大流量工况下流道内局部的气相聚集得到了改善.此外,由于高黏度条件下流道内湍流黏度较低以及剪切涡较多,所以在考虑刚性旋转时的涡量分布更为准确.研究结果可为油气混输泵的优化设计等提供理论参考.

2219铝合金搅拌摩擦焊缝Al2Cu相聚集行为特征分析

对2219C10S状态铝合金进行搅拌摩擦焊接试验,发现焊缝中存在聚集物的异常聚集现象,聚集相在X光检测中显示为亮白色聚集物,主要形态分为团块状、线状和指状三种,聚集相处焊缝的力学性能与无聚集相焊缝的力学性能基本相同。各形态聚集相的分布位置受搅拌头焊接影响区域的不同而不同,团块状聚集相主要存在于焊核中心或偏焊缝上表面位置处,线状和指状聚集相主要存在于焊核中心或偏焊缝根部位置处。对异常聚集相进行能谱分析知,聚集相主要组成元素为Al和Cu,原子百分比近似为2∶1,确定聚集相主要成分为Al2Cu。对聚集相的成因进行分析认为,聚集相的产生主要受搅拌摩擦焊接热输入及搅拌头机械搅拌作用的影响,在焊接过程中,塑态软化金属中的Al2Cu在填补搅拌针后方空腔的过程中出现了聚集行为,随着塑态金属的凝固,聚集行为开始变得缓慢并结束。

叶顶间隙对多相混输泵内流动特性的影响

为了揭示叶顶间隙对多相混输泵内流动特性的影响规律,在进口含气率为10%时,利用ANSYS CFX软件对不同叶顶间隙下泵内气液两相流态进行模拟,同时分析和总结了叶顶间隙对流道内流动特性的影响.研究表明,当叶顶间隙增加时,叶轮叶片进口附近低压区占比明显减少,并且叶轮进出口的压差也在逐渐减小.另外,在靠近叶片顶端时,压力等值线存在偏折现象.随着叶顶间隙逐渐增加,偏折加剧.存在叶顶间隙时,叶轮轮毂附近气相聚集得到了明显的改善,并且随着叶顶间隙的增加,气相在叶顶间隙内靠近叶顶处的聚集现象更加明显,导叶轮毂气相聚集位置沿着流动方向向下游移动.研究结果可为多相混输泵水力优化、性能改善和结构设计等提供依据.同时,研究结果进一步揭示了多相混输泵叶顶间隙流对混输泵性能的影响规律.

基于变转速控制的对旋轴流泵混输特性分析

由前置叶轮和后置叶轮反向旋转组成的对旋轴流泵有设计结构更紧凑、效率更高、性能更好的特点。由于气液混输泵是现代石油勘探及输送技术的一个重要研究方向,因此有必要研究对旋轴流泵的气液混输特性。应用计算流体力学的方法对不同工况下的对旋轴流泵进行数值模拟。分析对旋轴流泵的载荷分布以及变转速控制对其内部流动结构、气相分布的影响。计算结果表明:气相向轮毂侧移动,液相向轮缘侧流动,后置叶轮的气相聚集现象比前置叶轮更明显,气相聚集在逆压力梯度区域。分析了变转速控制法对混输泵性能的影响,两种变转速控制方法均能提高扬程和效率。在前置叶轮转速控制法(CFS)中湍动能变化曲线是单峰曲线;在后置叶轮转速控制法(CRS)中湍动能变化是双峰曲线。比较两种叶轮控制方法的湍流动能轴向分布曲线,发现前置叶轮控制方法的湍动能曲线均高于后叶轮控制方法的湍动能曲线,表明前置叶轮转速控制法湍流扩散程度更剧烈。

Pressure Buildup Analysis Using Type Curves for a Well in a Pressure-Maintained System

The development and application of a new solution is demonstrated for the type-curve analysis and in-terpretation of well test data from a multiwell reservoir system of both production and injection wells with two-phase flow. The buildup type curves or buildup behavior could be obtained through the solution by using su-perposition. But a new outer boundary condition for variable pressure boundary must be introduced to obtain the correct pressure buildup solutions by superposition. A technique is shown to determine the deviation time from the infinite-acting semilog radial flow stabilization in the derivatives of pressure, which is calculated with respect to and plotted vs. shut-in time. Field examples are given to illustrate the use of the proposed method for analyzing transient pressure data from a well located in a multi-well water-injection reservoir. An adaptive genetic algorithm-based method is used to match the pressure and pressure derivative data to estimate reservoir parameters. The validity and applicability of the proposed method are also demonstrated through the examples.

Extended DLVO theory applied to coal slime-water suspensions

Coal slimes are mainly composed of coal and clay particles.The interaction energies among these particles were calculated using extended DLVO(DERJAGUIN-LANDAU-VERWEY-OVERBEEK)theory and the aggregation mechanisms were analyzed based on the settling experiments for coal-kaolinite and coal-montmorillonite suspensions,respectively,under different conditions of water hardness.The results indicate that for coal-kaolinite suspensions,as the water hardness reaches 10.0mol/L,the coal particles aggregate with each other easily,and then,the coal particles may aggregate with kaolinite particles.However,no aggregation occurs between kaolinite particles.A clay platelet network is formed in coal-montmorillonite suspensions by montmorillonite particles and coal particles are captured into the network.Coal and montmorillonite particles settle completely.

Effect of additives on growth of ferronickel grains and metal-slag separation behavior

Na_(2)S,Na_(2)CO_(3),FeO,FeS and carbon were used to regulate the properties of slag or metal fractions,and their effects on metal growth and metal–slag separation behavior were investigated.The growth of ferronickel grains can be enhanced by adding these additives,and Na_(2)S was the most effective.Na_(2)S,Na_(2)CO_(3) and FeO mainly affected the properties of slag,while carbon and FeS affected the metal fraction.The onset temperature of metal–slag separation was 1297℃ for the sample without additive,which was decreased to 1123 and 1101℃ after adding 3.30 wt.%Na_(2)S and 4.47 wt.%Na_(2)CO_(3),respectively.The onset temperature of metal–slag separation was mainly controlled by the slag fraction.The average apparent activation energy of metal grain growth was 125.32 kJ/mol without additive,and it decreased obviously after adding different additives.Na_(2)S also had the most remarkable effect on the decrease in activation energy.

Aggregation Behaviors of a Two-Species System with Lose-Lose Interactions

We propose an aggregation evolution model of two-species （A- and B-species） aggregates to study the prevalent aggregation phenomena in social and economic systems. In this model, A- and B-species aggregates perform self-exchange-driven growths with the exchange rate kernels K（k, l） = Kkl and L（k, l） = Lkl, respectively, and the two species aggregates perform self-birth processes with the rate kernels J1（k） = J1 k and J2（ k ） = J2k, and meanwhile the interaction between the aggregates of different species A and B causes a lose-lose scheme with the rate kernel H（k,l） = Hkl. Based on the mean-field theory, we investigated the evolution behaviors of the two species aggregates to study the competitions among above three aggregate evolution schemes on the distinct initial monomer concentrations A0 and B0 of the two species. The results show that the evolution behaviors of A- and B-species are crucially dominated by the competition between the two self-birth processes, and the initial monomer concentrations Ao and Bo play important roles, while the lose-lose scheme play important roles in some special cases.

Microstructure and mechanical properties of Al-6.02Zn-1.94Mg alloy at higher solution treatment temperature

The effects of solution treatment temperature and holding time on the microstructure and mechanical properties of extruded Al-6.02 wt.%Zn-1.94 wt.%Mg alloy were investigated by differential scanning calorimetry(DSC),optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), and tensile test. The results showed that the optimum solution treatment process for the alloy was 470 ℃, 2 h. The tensile strength, yield strength,and elongation of the samples after the aging treatment at 120℃ for 24 h were 486 MPa, 431 MPa, and 14.8%,respectively. The alloy produced more copious recrystallization with the augment of solution temperature and the extension of holding time. While the second phase of η(MgZn_(2)), and T(AlZnMgCu) in the matrix was not fully re-dissolved under the treatment condition of lower temperature or shorter holding time. Interestingly, the Zr aggregation was observed in the samples treated at 510 ℃ for 2 h, which led to the growth of the second phase particles and the increase of their area fraction.

Using PVP/SDS Complex as a Probe to Study the Inclusion Complex of β-cyclodextrin with SDS in Aqueous Solution

PVP/SDS complex was applied as a probe to study the interaction between β-cyclodextrin （β-CD） and sodium dodecyl sulfate （SDS） in aqueous solution. It has been found that a critical concentration, namely cs, exists in the relative viscosity of solution containing PVP/SDS complex versus β-CD concentration plot. As the β-CD concentration is less than cs, the relative viscosity of solution decreases sharply by adding β-CD into solution successively. On the other hand, as the β-CD concentration is greater than cs, the relative viscosity of solution increases gradually by adding β-CD into solution. The decrease of the relative viscosity of solution containing PVP/SDS in the presence of β-CD is just due to the inclusion complex of β-CD with the guest molecule SDS. And, this inclusion interaction takes down SDS from the PVP chains in solution. The ratio of the host molecule β-CD to the guest molecule SDS can be calculated from Cs. In our experiment the inclusion ratio of β-CD to SDS is 1/1. The further experimental results indicate that cs is associated with SDS but free from PVP in PVP/SDS complex. However, the inclusion ratio of β-CD to SDS has proved to be independent of either SDS or PVP in PVP/SDS complex.

Effect of Energy Transfer on UV Spectra of “H-shaped” Azobenzene Derivatives

A series of “H-shaped” organic dimers （azobenzene derivatives） exhibit linear absorption red shift compared with their corresponding monomers experimentally. Dipolar interaction model is not appropriate for the azobenzene derivatives due to the small distance between two “D-π-A” chains. Energy transfer model is suggested for explanation of the absorption red shift. Two necessary conditions for energy transfer were verified. In addition, bi-exponential florescence-delay behavior of the dimer as well as Bella＇s quantum chemistry calculation shows evidence of energy transfer.

Photo-induced morphology transition of a multifunctional photochromic bisthienylethene molecule with switchable aggregation-induced emission

A novel multifunctional molecule BTE-CNPH was designed and synthesized by connecting 2-(3′,5′-bis(trifluoromethyl)-biphenyl-4-yl)-2-cyanovinyl group to both side of the bisthienylethene(BTE), which exhibited excellent aggregation-induced emission(AIE) and bistable photochromism. High-contrast(>60) reversible fluorescence switching was achieved in the 1 D nanowires, solid of BTE-CNPH and also in a polymethyl methacrylate(PMMA) film loaded with 1% BTE-CNPH under the alternative irradiation by 365 nm and visible light. Interestingly, the nanowire-like assembly morphology of BTE-CNPH in aqueous tetrahydrofuran(THF) solution of specific concentration was observed to translate into amorphous pieces gradually upon prolonged irradiation by the 365 nm, accompanying with photo-tunable AIE emission.

Patterns of color phase indicate spawn timing at a Nassau grouper Epinephelus striatus spawning aggregation

Nassau grouper Epinephelus striatus are a large bodied, top level predator that is ecologically important throughout the Caribbean. Although typically solitary, Nassau grouper form large annual spawning aggregations at predictable times in spe- cific locations. In 2003, The Cayman Islands Marine Conservation Board established protection for a newly rediscovered Nassau grouper spawning aggregation on Little Cayman, British West Indies. The large size of this aggregation provides a unique oppor- tunity to study the behavior of Nassau grouper on a relatively intact spawning aggregation. During non-spawning periods Nassau grouper display a reddish-brown-and-white barred coloration. However, while aggregating they exhibit three additional color phases： ＂bicolor＂, ＂dark＂, and ＂white belly＂. We video sampled the population on multiple days leading up to spawning across five spawning years. Divers focused a laser caliper equipped video camera on individual fish at the aggregation. We later ana- lyzed the video to determine the length of the fish and record the color phase. Our observations show that the relative proportion of fish in the bicolor color phase increases significantly on the day leading up to the primary night of spawning. The increase in the proportion of the bicolor color phase from 0.05 early in the aggregation to 0.40 on the day of spawning suggests that this color phase conveys that a fish is behaviorally and physiologically prepared to spawn. Additionally, 82.7% of fish exhibiting dark or white belly coloration early in the aggregation period suggests that these color phases are not only shown by female fish as was previously posited [Current Zoology 58 （1）： 73-83, 2012].

Sectoral Agglomeration and Urban Development： The History of Tunxi--The Tea Business Centre in Huizhou

From the perspective of historical geography, Tunxi as the chosen centre for tea production in the Qing could not be explained geographically alone by the river system of Huizhou, in which stead this article attempts a historicogeographical analysis by shifting our attention towards the sector-specific agglomeration of rel- evant industries and urbanisation. Due to the restrictions by the imperial government on using sea ports （e.g. Shanghai） for the transportation of tea south- wards for sale and export, Tunxi was made the centre for tea trade, not only due to its geographical convenience to tax clearance, but also because of the agglomeration of tea-related industries in the City, such as tin-can, box and bamboo-crate ware- houses. There also had emerged in this process a conglomeration of daily life services, making Tunxi a place of convenience-cure-prosperity. Thus, a combination of both historical and geographical factors can help in no small way to offer a better explanation of the urban development of Tunxi as a tea trade centre in imperial China.

Micellization of copolymers via noncovalent interaction with TPPS and aggregation of TPPS

Aggregation of 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) was investigated in complex micelles composed of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) and poly(2-(dimethylamino)ethyl methylacrylate)-b-poly(Nisopropylacrylamide) (PDMAEMA-b-PNIPAM) in aqueous solutions.The resultant complex micelles had a complex P4VP/ PDMAEMA/TPPS core and a mixed PEG/PNIPAM shell.Different noncovalent interaction modes between the porphyrin and each copolymer accomplished a co-effect on the aggregation of TPPS.The formation of aggregates was pH-dependent.At pH 3.2–6.5,TPPS existed as a mixture of H-aggregates and monomers because of the aromatic-aromatic interaction with P4VP and electrostatic interaction with PDMAEMA.The monomers translated into J-aggregates,stabilized by electrostatic interaction with the both polyelectrolyte blocks,upon decreasing the pH to 1.6.The free-base monomer was the one and only form for the dye at pH 11.0 due to aromatic stacking with the pyridyl rings.

The Behavior of Solutions of Multidimensional Aggregation Equations with Mildly Singular Interaction Kernels

The authors consider the multidimensional aggregation equation tp-div（p K＊ ρ） = 0 in which the radially symmetric attractive interaction kernel has a mild singularity at the origin （Lipschitz or better）, and review recent results on this problem concerning well-posedness of nonnegative solutions and finite time blowup in multiple space dimensions depending on the behavior of the kernel at the origin. The problem with bounded initial data, data in L^p ∩ L^1, and measure solutions are also considered.

Controllable synthesis and spontaneous phase transition of photonic coordination polymer to produce a strong second-harmonic generation response

Herein,a novel photonic coordination polymer material was constructed by aggregation-induced emission luminogen(AIEgen)containing a tripyridyl moiety used as the linking ligand.It displayed a spontaneous direct centrosymmetric to noncentrosymmetric phase transition in a single crystal.The two crystals,before and after the phase transition,were both controllably synthesized and characterized by single-crystal X-ray diffraction.After being exposed to air,the centrosymmetric metastable phase(1-α)transitioned to a new stable phase with a noncentrosymmetric structure(1-β).Interestingly,the 1-βstructure exhibited a strong phasematching second-harmonic generation(SHG)response,about4.5 times higher than that of KH2PO4(KDP).In order to better understand the relationship between the structure and the nonlinear optical properties,the dipole moments were calculated and discussed.Remarkably,the noncentrosymmetric phase with high thermal stability for 1-βretained and improved the initial photoluminescent properties of the AIEgen ligand after the structural phase transition from 1-α,and simultaneously produced the excellent SHG property,which are beneficial for the design and construction of excellent optical materials.