Hydrogen bonding and π–π stacking in 6‐hydroxy­biochanin A monohydrate

In the lattice of the title compound (systematic name: 5,6,7‐trihydroxy‐4′‐meth­oxy­isoflavone monohydrate), C₁₆H₁₂O₆·H₂O, the isoflavone mol­ecules are linked into chains through R₄³(17) motifs composed via O—H⋯O and C—H⋯O hydrogen bonds. Centrosymmetric R₄²(14) motifs assemble the chains into sheets. Hydrogen‐bonding and aromatic π–π stacking inter­actions lead to the formation of a three‐dimensional network structure.     

Collaborative applications based on the internet

The basic concepts of collaborative applications and some relevant aspects about network communications are introduced. With the examples of some collaborative applications developed by us, several technical problems about collaborative applications, such as loss of data packets, unknown IP address and timedelay, are discussed in detail. And the methods of solving these problems are also provided. Supported by International Cooperation Project (Japan, Jincheng Co. Ltd) Fang Rui: born in 1975, Graduate student     

驻马店市集中式污染治理设施普查与分析

根据2007年第一次全国污染源普查中驻马店市集中式污染治理设施的区域分布、建设类型与运营情况的统计数据,分析了该市集中式污染治理设施的实际处理能力以及目前运营存在的问题和原因,并结合2008年该市全市污水处理厂的管网建设、运营情况、污泥成分分析以及2010年该市减排任务,有针对性地提出了对策建议.     

Sorption equilibria of CO2 on silica-gels in the presence of water

The sorption equilibria of carbon dioxide on three types of silica gel (SG) with different pore size distributions in the presence of water were studied experimentally using a volumetric method at 275?K with pressures from 0 to 3.7?MPa. Both the pore size distribution of the silica gel and the quantity of pre-sorbed water impact the formation of the CO₂ hydrates. For wet silicon gel A(SG-A) with water loading ratio of 0.75, the highest CO₂ sorption was about 2.5?mmol of CO₂ per gram of dry sorbent at 275?K. Similarly, the highest sorption was about 2.7?mmol for wet SG-B with R _w =0.81. However, CO₂ hydrate did not form on the wet surface of SG-C due to its large pore sizes.     

Nonlinear analysis of relativistic harmonic generation by intenselasers in plasmas

A linearly polarized, ultraintense laser field induces transverse plasma currents which are highly relativistic and nonlinear, resulting in the generation of coherent harmonic radiation in the forward direction (i.e., copropagating with the incident laser field). A nonlinear cold fluid model, valid for ultrahigh intensities, is formulated and used to analyze relativistic harmonic generation. The plasma density response is included self-consistently and is shown to significantly reduce the current driving the harmonic radiation. Phase detuning severely limits the growth of the harmonic radiation. The effects of diffraction are considered in the mildly relativistic limit. No third-harmonic signal emerges from a uniform plasma of near-infinite extent. A finite third-harmonic signal requires the use of a semi-infinite or finite slab plasma. For an initially uniform plasma, no second-harmonic radiation is generated. Generation of even harmonics requires transverse gradients in the initial plasma density profile     

Threshold gain behavior of lasing modes in two-dimensional active random media

The pumping rate dependence of the peak intensity of the individual lasing mode in two-dimensional (2D) active random media is investigated. The results show that these modes have a typical threshold gain behavior and different threshold pumping rates. There exists a certain correspondence between the mode's threshold pumping rate and its lifetime, and the longer the lifetime is, the lower the threshold is.     

ICP-AES测定钾石盐中的硫酸根离子

在选定的最佳条件下,样品直接溶解后采用ICP-AES测定钾石盐中硫酸根离子的含量,其最终检测结果与化学法测定结果一致。该方法简便、快速、线性范围宽、测量稳定。回收率为89.0%—102.0%。     

微波辐射法合成N-苯基马来酰亚胺

用微波辐射法合成N-苯基马来酰亚胺,在总结前人对原料配比、催化剂用量对反应收率影响的基础上,本实验以顺丁烯二酸酐和苯胺为原料用醋酐作脱水剂、醋酸钠作催化剂采用微波辐射法两步合成N-苯基马来酰亚胺。探讨最佳工艺条件为第一步用微波功率80W熟化3min,第二步用微波以功率400W加热1.5min时N-苯基马来酰亚胺的收率可达75.8%。产品经晶形、熔点和红外光谱分析确定为目标产品。     

长腰内锥流量计的特性研究

内锥式流量计在多相流测量中的应用逐渐受到广大多相流研究工作者的重视。针对内锥式流量计在多相流测量中存在的一些问题,提出一种新型的环形通道式差压流量计—长腰内锥流量计。通过理论推导得出流量方程及永久压损与流量的关系式,并通过在水相、油相、气相条件下的标定实验,定量分析流出系数与永久压损等特性。结果表明:在长腰内锥体腰部取低压可以在保证差压信号幅值的情况下提高其稳定性、重复性;长腰内锥流量计节流件的轮廓及固定方式可以显著地减小永久压损。为后期开发新型多相流测量仪器提供理论依据与设计基础。