Magnifying the Structural Components of Biomembranes: A Prototype for the Study of the Self-Assembly of Giant Lipids

How biomembranes are self-organized to perform their functions remains a pivotal issue in biological and chemical science. Understanding the self-assembly principles of lipid-like molecules hence becomes crucial. Herein, we report the mesostructural evolution of amphiphilic sphere-rod conjugates (giant lipids), and study the roles of geometric parameters (head–tail ratio and cross-sectional area) during this course. As a prototype system, giant lipids resemble natural lipidic molecules by capturing their essential features. The self-assembly behavior of two categories of giant lipids (I-shape and T-shape, a total of 8 molecules) is demonstrated. A rich variety of mesostructures is constructed in solution state and their molecular packing models are rationally understood. Giant lipids recast the phase behavior of natural lipids to a certain degree and the abundant self-assembled morphologies reveal distinct physiochemical behaviors when geometric parameters deviate from natural analogues.     

不确定车轨耦合系统辛随机振动分析

建立了轨道不平顺作用下具有不确定参数车轨耦合系统随机振动评估方法. 车辆系统采用物理坐标下多刚体系统模型,并应用高斯随机变量模拟车体、转向架和轮对一系、二系连接系统中动力学参数具有的不确定性. 采用无穷周期结构进行弹性轨道模拟,在哈密顿状态空间下建立了典型轨道子结构的状态运动方程,通过轮轨耦合关系建立了混合 物理坐标及辛模态坐标车轨耦合系统运动方程. 应用Hermite正交多项式展开得到了耦合系统动力响应相对于不确定性参数的控制方程. 由于利用轨道周期特性建模,所获得的控制方程有效地降低了方程维度. 轮轨接触处轨道不平顺载荷模拟为完全相干多分量平稳随机过程,推广和发展虚拟激励法建立了耦合系统随机振动受不确定动力学 参数影响的量化评估方法. 通过Monte Carlo数值模拟,验证了该方法在不确定参数变异很大时也能够保持较好的精度,具有一定的工程实用性.     

大跨度结构考虑行波效应时平稳随机地震响应的闭合解

给出了大跨度结构考虑行波效应时平稳随机地震响应的闭合解．通过算例讨论了行波效应对大跨度结构响应的影响．结果表明,行波效应可对大跨度结构响应产生显著影响,在实际应用时应予以考虑。     

Surface Modification Based on Diselenide Dynamic Chemistry: Towards Liquid Motion and Surface Bioconjugation

Surface modification is an important technique in fields, such as, self‐cleaning, surface patterning, sensing, and detection. The diselenide bond was shown to be a dynamic covalent bond that can undergo a diselenide metathesis reaction simply under visible light irradiation. Herein we develop this diselenide dynamic chemistry into a versatile surface modification method with a fast response and reversibility. The diselenide bond could be modified onto various substrates, such as, PDMS, quartz, and ITO conductive film glass. Different functional diselenide molecules could then be immobilized onto the surface via diselenide metathesis reaction. We demonstrated that by using this modification method we could achieve liquid motion in a capillary tube under light illumination. We also show that this approach has the potential to serve as an efficient modification method for surface bioconjugation, which has practical applications in clinical usage.     

Palladium(0)‐Catalyzed Directed syn‐1,2‐Carboboration and ‐Silylation: Alkene Scope,Applications in Dearomatization,and Stereocontrol by a Chiral Auxiliary

We report the development of palladium(0)‐catalyzed syn‐selective 1,2‐carboboration and ‐silylation reactions of alkenes containing cleavable directing groups. With B₂pin₂ or PhMe₂Si‐Bpin as nucleophiles and aryl/alkenyl triflates as electrophiles, a broad range of mono‐, di‐, tri‐ and tetrasubstituted alkenes are compatible in these transformations. We further describe a directed dearomative 1,2‐carboboration of electron‐rich heteroarenes by employing this approach. Through use of a removable chiral directing group, we demonstrate the viability of achieving stereoinduction in Heck‐type alkene 1,2‐difunctionalization. This work introduces new avenues to access highly functionalized boronates and silanes with precise regio‐ and stereocontrol.     

A Photochemical Route towards Metal Sulfide Nanosheets from Layered Metal Thiolate Complexes

Synthesizing nanomaterials with anisotropic architectures, especially two‐dimensional (2D) nanosheets (NSs), is a key focus of materials science research. Metal sulfide nanosheets (MSNSs) are typically obtained involving exfoliation of bulk metal sulfides with layered structures. The synthesis of NSs of intrinsically non‐layered metal sulfides has received relatively less attention. Metal alkanethiolates with lamellar structures are now shown to serve as effective scaffolds for constructing NSs. A novel photochemical step was employed to transform 2D metal thiolates into MSNSs. By this strategy the 2D nature of metal thiolate precursors was preserved in the final products, resulting in the successful synthesis of NSs of binary PbS, CdS, and Cu₉S₅, as well as ternary wurtzite CuInS₂, Cu₂SnS₃. Results encourage the wider utilization of photochemical strategies in the synthesis of anisotropic MSNSs.     

Ultrafast Growth of Large Area Graphene on Si Wafer by a Single Pulse Current

Graphene has many excellent optical, electrical and mechanical properties due to its unique two-dimensional structure. High-efficiency preparation of large area graphene film is the key to achieve its industrial applications. In this paper, an ultrafast quenching method was firstly carried out to flow a single pulse current through the surface of a Si wafer with a size of 10 mm × 10 mm for growing fully covered graphene film. The wafer surface was firstly coated with a 5-nm-thick carbon layer and then a 25-nm-thick nickel layer by magnetron sputtering. The optimum quenching conditions are a pulse current of 10 A and a pulse width of 2 s. The thus-prepared few-layered graphene film was proved to cover the substrate fully, showing a high conductivity. Our method is simple and highly efficient and does not need any high-power equipment. It is not limited by the size of the heating facility due to its self-heating feature, providing the potential to scale up the size of the substrates easily. Furthermore, this method can be applied to a variety of dielectric substrates, such as glass and quartz.     

单原子催化的关键进展与未来挑战

单原子催化剂(SACs)兼具均相与多相催化剂的双重优势, 表现出最大化的原子利用率、 超高的本征活性与选择性以及易与产物分离的特点, 受到人们的广泛关注. 然而, 由于单个原子较高的表面能以及不稳定性, 设计与制备单原子催化剂仍是一大挑战. 本文综合评述了近年来单原子催化剂的稳定化策略、 高载量催化剂的制备方法以及批量制备技术等方面的关键研究进展, 并简要分析了单原子催化剂未来发展所面临的问题与挑战, 最后对单原子催化的发展方向进行了展望.     

关于虚拟激励法与结构随机响应的注记

虚拟激励法自发表以来，引起了学术界和工程界的较大关注。特别是在处理大型复杂结构受多点随机激励时，该法自动计及了参振振型的互相关以及激励之间的互相关，在理论上是精确解。而且该法对于处理非经典阻尼矩阵很方便，在一般具有简谐振动／时程分析功能的有限元程序上进一步开发计算位移，内力，应变等各种平稳／非平稳响应量的自谱互谱计算功能都十分方便，所以获得了较多应用。对该算法的适应性和计算效率与传统算法明确地给出对比，将对其理解与推广应用有很大好处。本文将对此作一些说明。     

DDJ-W软件系统的新进展

本文综述了国产DDJ-W微机软件系统在结构静力分析、动力分析、稳定性分析、结构优化、复合材料力学性能分析、前后处理功能等方面的近期进展,以及工程应用情况。