玻璃纤维带隙间环氧胶渗流特性的试验研究

对环氧胶在含有玻璃纤维带的间隙中的渗流进行了试验研究. 通过试验确定纤维的松紧度、输胶压力、抽口真空度和输胶温度等不同参数对渗流流速的影响,为环氧胶的VPI(真空压力浸渍或浇铸)工艺提供工艺参数.     

构造本构方程的另一种方法——非平衡不可逆热力学方法

重点介绍了以Onsager-Casimir倒易定律为基础,从不可逆热力学观点出发,对远离平衡状态,引进新的变量(被称为动态变量),构造本构方程．并以简单剪切流场为例,求出了测黏函数．     

预应力钢梁体外索的张力增量分析

将预应力钢梁看作梁与索的组合结构,充分考虑了二者之间的相互作用．利用变分原理推导出在外荷载作用下,体外索张力增量的计算公式,并通过预应力钢梁模型试验对计算结果进行了验证．     

Photostabilizing activity of sterically hindered piperidines—II: Radical trapping ability

The abilities of both 2,2,6,6-tetramethylpiperidine (I) and its nitroxyl (II) to trap radicals involved in hydrocarbon photo-oxidations have been studied in cumene and 1,3,5-trimethylcyclohexane at 27° using AIBN, hydroperoxide and dialkylperoxide as initiators: the light was either the band 300–400 nm or 366 nm. Under conditions of photolysis of ROOH (degenerate branching), I is oxidized to II. II is capable of trapping R' radicals, the rate constant being ～50 times lower than that for RO^.₂ formation. RO^.₂ radicals react with neither I nor II. Under the condition of degenerate branching, II is capable of intercepting the radical fragments from decomposing hydroperoxide. The rate constant of this process is ～500 times higher than that for hydrogen abstraction by these fragments. A reaction mechanism is suggested: hydrogen bonded associates formed between an N-containing stabilizer and ROOH play a dominant role. The principal intermediates in this mechanism are represented by >NO^., >NOH and >NOR species.     

On a chip demonstration of a functional role for Odorant Binding Protein in the preservation of olfactory receptor activity at high odorant concentration

The molecular mechanisms underlying odorant detection have been investigated using the chip based SPR technique by focusing on the dynamic interactions between transmembrane Olfactory Receptor OR1740, odorant ligands and soluble Odorant-Binding Protein (OBP-1F). The OR1740 present in the lipid bilayer of nanosomes derived from transformed yeasts specifically bound OBP-1F. The receptor preferential odorant ligand helional released bound OBP-1F from the OR-OBP complex, while unrelated odorants failed to do so. OBP-1F modified the functional OR1740 dose-response to helional, from a bell-shaped to a saturation curve, thus preserving OR activity at high ligand concentration. This unravels an active role for OBPs in olfaction, in addition to passive transport or a scavenger role. This sensorchip technology was applied to assessing native OBP-1F in a biological sample: rat olfactory mucus also displayed significant binding to OR1740 nanosomes, and the addition of helional yielded the dissociation of mucus OBP from the receptor.     

Transannular rearrangement of activated 2,5-diketopiperazines: a key route to original scaffolds

An efficient and original stereocontrolled transannular rearrangement starting from activated 2,5-diketopiperazines has been developed, an opportunity for the medicinal chemistry field, which requests access to novel biological scaffolds. This powerful ring contraction, which can be related to a stereoselective aza-version of the Chan rearrangement, allows for example the one-step synthesis of various tetramic acids, access to 2-disubstituted statins, or the synthesis of relevant lactam-constrained dipeptide mimetics using a TRAL-RCM sequence.     

Synthesis and Characterization of Intercluster Compounds Consisting of Various Gold Clusters and Differently Charged Keggin Anions

The crystal structures of five intercluster compounds consisting of gold clusters and Keggin anions have been determined by single‐crystal x‐ray diffraction: [Au₉(PPh₃)₈][PMo₁₂O₄₀] (P4/n, Z = 2, a = 24.0195(13), c = 13.6818(10) Å), [Au₉(PPh₃)₈][HSiMo₁₂O₄₀] (P4/n, Z = 2, a = 24.270(3), c = 13.752(2) Å), [Au₉(PPh₃)₈][H₃CoW₁₂O₄₀] (P4/n, Z = 2, a = 24.4776(16), c = 13.7759(13) Å), [Au₈(PPh₃)₈]₂[SiMo₁₂O₄₀] (Pbca, Z = 4, a = 36.269(4), b = 24.488(3), c = 38.612(4) Å) and (nBu₄N)[Au₉(Ptol₃)₈][SiMo₁₂O₄₀] (Cc, Z = 4, a = 24.832(5), b = 24.955(5), c = 40.096(8) Å, β = 106.744(3)°). In these compounds, the charges of the building blocks were varied. Altering the charge on the Keggin anion in combination with the [Au₉(PPh₃)₈]³⁺ cluster gave rise to isostructural compounds as the charge is compensated by protonation of the polyoxometalate anion. Varying the charge or the ligand type of the gold cluster led to compounds with a completely different packing principle.     

Adsorption of aromatic hydrocarbons and ozone at environmental aqueous surfaces

Adsorption of environmentally important aromatic molecules on a water surface is studied by means of classical and ab initio molecular dynamics simulations and by reflection-absorption infrared spectroscopy. Both techniques show strong activity and orientational preference of these molecules at the surface. Benzene and naphthalene, which bind weakly to water surface with a significant contribution of dispersion interactions, prefer to lie flat on water but retain a large degree of orientational flexibility. Pyridine is more rigid at the surface. It is tilted with the nitrogen end having strong hydrogen bonding interactions with water molecules. The degree of adsorption and orientation of aromatic molecules on aqueous droplets has atmospheric implications for heterogeneous ozonolysis, for which the Langmuir-Hinshelwood kinetics mechanism is discussed. At higher coverages of aromatic molecules the incoming ozone almost does not come into contact with the underlying aqueous phase. This may rationalize the experimental insensitivity of the ozonolysis on the chemical nature of the substrate on which the aromatic molecules adsorb.     

On the Cohen-Macaulayness of fiber cones

Let be a Noetherian local ring with the maximal ideal and an ideal of Denote by the fiber cone of This paper characterizes the multiplicity and the Cohen-Macaulayness of fiber cones in terms of minimal reductions of ideals.

     

Remarks on D-integral complete multipartite graphs

A graph is called distance integral (or D-integral) if all eigenvalues of its distance matrix are integers. In their study of D-integral complete multipartite graphs, Yang and Wang (2015) posed two questions on the existence of such graphs. We resolve these questions and present some further results on D-integral complete multipartite graphs. We give the first known distance integral complete multipartite graphs \({K_{{p_1},{p_2},{p_3}}}\) with p₁ < p₂ < p₃, and \({K_{{p_1},{p_2},{p_3},{p_4}}}\) with p₁ < p₂ < p₃ < p₄, as well as the infinite classes of distance integral complete multipartite graphs \({K_{{a_1}{p_1},{a_2}{p_2},...,{a_s}{p_s}}}\) with s = 5, 6.