顶端受集中力偶的双材料平面界面接合楔体的对数奇异应力场

应用复变函数方法,通过构造复函数形式的特解序列,从理论上研究了顶端受集中力偶的双材料平面界面接合楔体的应力场,给出了相应的经典解,发现其存在一次和二次佯谬,相应的应力具有(Inr)／r2和(In2r)／r2的奇异性。     

A new formula for the saddle-to-scission time

We propose a new formula for the saddle-to-scission time that is more general that the one based on Kramers' approach. Its validity and applicability is then studied in detail. Such a formula is useful for the evaluation of the fission time of very heavy nuclei.     

Effect of Laser-Induced Optical Breakdown on the Structure of Bsa Molecules in Aqueous Solutions: An Optical Study

The influence of laser radiation of a typical surgical laser on the physicochemical properties of the Bovine Serum Albumin (BSA) protein was studied. It was established that the physicochemical characteristics of optical breakdown weakly depend on the concentration of protein molecules. At the same time, the patterns observed for an aqueous solution of BSA irradiated with a laser for different time periods were extremely similar to the classical ones. It was established that after exposure to laser radiation, the optical density of protein solutions increases. At the same time, the intensity of BSA fluorescence due to aromatic amino acid residues decreases insignificantly after exposure to laser radiation. In this case, the position of the excitation and emission maximum does not change, and the shape of the fluorescence spot on 3D maps also does not change significantly. On the Raman spectrum after exposure to laser radiation, a significant decrease in 1570 cm⁻¹ was observed, which indicates the degradation of α-helices and, as a result, partial denaturation of BSA molecules. Partial denaturation did not significantly change the total area of protein molecules, since the refractive index of solutions did not change significantly. However, in BSA solutions, after exposure to laser radiation, the viscosity increased, and the pseudoplasticity of aqueous solutions decreased. In this case, there was no massive damage to the polypeptide chain; on the contrary, when exposed to optical breakdown, intense aggregation was observed, while aggregates with a size of 400 nm or more appeared in the solution. Thus, under the action of optical breakdown induced by laser radiation in a BSA solution, the processes of partial denaturation and aggregation prevail, aromatic amino acid residues are damaged to a lesser extent, and fragmentation of protein molecules is not observed.     

Oxime radical promoted dioxygenation, oxyamination, and diamination of alkenes: synthesis of isoxazolines and cyclic nitrones

Up the tempo: The intramolecular addition of oxime radicals to C?C bonds was achieved by using DEAD and TEMPO to give 4,5-dihydroisoxazoles as a result of a C?O bond-forming, 5-exo-trig cyclization. γ,δ-Unsaturated ketoximes also reacted to afford cyclic nitrones through C?N bond formation. The reactions offer a metal-free approach for the vicinal difunctionalization of unactivated alkenes.     

Expeditious Synthesis of Enantiopure,Orthogonally Protected Bis‐α‐Amino Acids (OPBAAs) and their Use in a Study of Nod1 Stimulation

A convenient approach towards the synthesis of orthogonally protected chiral bis‐α‐amino acids (OPBAAs) is described. The key transformations include: (1) a highly stereoselective conjugation (alkylation) of the Schöllkopf bis‐lactim ethers and oxazolidinyl alkyl halides to build a backbone skeleton; and (2) our orthogonal protection strategy. A series of enantiopure OPBAAs bearing a variety of alkyl chain as a spacer; two stereogenic centers; and three protecting groups were prepared as examples. These versatile molecules were applied to the synthesis of biologically interesting di‐ or tri‐peptide analogues, including chiral iE‐meso‐DAP and A‐iE‐meso‐DAP, for the study of Nod1 activation in the innate immune response.     

A semilinear elliptic PDE not in divergence form via variational methods

In this paper we consider a semilinear equation driven by an operator not in divergence form. Precisely, the principal part of the operator is in divergence form, but it has also a lower order term depending on Du. While the right-hand side of the equation satisfies superlinear and subcritical growth conditions at zero and at infinity. The problem has not a variational structure, but, despite that, we use variational techniques in order to prove an existence and regularity result for the equation.     

国际“物理化学”课程与教学研究评述

通过文献的计量分析和阅读总结,我国物理化学课程与教学研究还局限于经验与思辨。我们梳理了国际权威期刊上研究物理化学教学的文献,将其分为教科书研究、学习研究、教学研究、教师研究和教学媒体研究等5类,并对其中核心成果进行评述。总结出国外物理化学课程与教学研究注重学习证据的收集和分析,注重教育研究方法的运用,并对于未来高等化学教育研究提出建议。