Effect of microwave heating time on the gel properties of chicken myofibrillar proteins and their formation mechanism

The present work was conducted to illustrate the mechanism of gel formation of myofibrillar proteins (MPs) under different microwave heating times. The results showed that the denaturation enthalpy (ΔH) of the MPs significantly decreased when the heating time increased from 3 to 9 s and then completely disappeared as the heating time progressed, indicating that the MPs gradually denatured and subsequently aggregated with increasing heating time, which was further verified by the changes in the secondary structure, electrophoretic bands, and gel properties (e.g., water holding capacity and textural profiles) of the MPs. Microstructural images indicated that the MP gel formed under 12 s had the most compact network, indicating that extended microwave heating time could induce quality deterioration of MP gels. Moreover, the hydrophobic forces, electrostatic forces, and disulphide bonds of the MPs gradually intensified with increasing microwave heating time, suggesting that both non-covalent and covalent bonds could promote molecular denaturation and subsequent aggregation of MPs. In addition, correlation analysis revealed that the changes in the molecular conformation of MPs induced by different microwave heating times could effectively regulate the formation of MP gels and their related properties.     

城市形象的建筑环境美学设计问题

城市形象是创造富于个性化城市的关键,而建筑环境美学设计水准则是体现城市形象的要素之一。据此,作者从分析中国城市形象的美学误区出发,研究了不同城市建筑品位的形成特点,进而提出塑造好宜人城市美学空间的科学思考。     

建筑制图标准中图形符号适宜性、区分性的研究

应用线段长短、间距大小视觉反应的量化规律，提出设计图形符号大小的原则——既更使其大小满足“长”“短”“大”“小”的心理要求，又要互相之间在大小上有区分性。根据图形组织的相似、接近、连续三原则提出设计图形符号形状的原则——图形符号之间尽量减少相似、接近、连续，以保证较好的区分性。通过分析发现，现行建筑制图标准中的图形符号绝大部分在大小和形状具有适宜性、区分性。     

居住建筑设计的点滴体会

根据石河子的地理位置、自然环境和居住建筑发展的历史,为当地设计了功能较全,布局合理,实用性强的住宅楼。通过设计实践对住宅设计提出了一些看法。     

Use of helical parameters to generate candidate conformations for crystal packing: illustrative application to a polyimide

This communication describes the application and extension of a method for calculating the helical parameters with which to describe molecular conformations. The method, which was originally developed by Shimanouchi and others, is applied to a polyimide of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 2,2-dimethyl-1,3-(4-aminophenoxy)propane (DMDA) which has eight torsional bonds in the chemical repeat unit. Discrete low energy states for these torsions were determined by Ramanchandran energy maps of sequential dihedral pairs or single bond torsional energy diagrams. The total number of possible low energy conformations for these states is 1152 including conformationally related isoenantiomorphs. The method conveniently generates the conformations for subsequent crystal structure packing and refinement. Consideration of these together with the X-ray data of Cheng and co-workers reduces the number to about 15 with about a 2/1 conformation and a c axis of approximately 49.2 Å. Of these, about half appear to be good candidates for crystal packing.     

Polyethylene mixed crystal infra-red spectroscopy: The influence of matrix isotopic species on guest conformation

The chain conformation of solution-crystallized polyethylene has previously been confirmed by infra-red spectroscopy, using the CD₂ bending bandshape for samples with a minority of the deuterated species^1–3. The method of calculating the i.r. band profile from molecular conformational models is now developed to give a more accurate representation of doublet splittings and to include the singlet component. The CH₂ bending profile is calculated for samples with a deuterated matrix, and the good agreement with experimental data indicates that the same molecular model is applicable for samples with the deuterated polymer as either guest or matrix, for identical crystallization conditions. This result implies that isotopic fractionation is unimportant under these conditions.     

迈向21世纪的建筑艺术观

自现代主义建筑艺术创作理论之后，建筑创作表现出一直被怀疑为某种程度的哗众取宏。在这些繁杂的理论争论中，我们面临着如何迈向21世纪新历程的挑战？如何面对电脑、信息和新技术的冲击，避免建筑创作中人的主创作用的消蚀，是建筑创作迈向21世纪的重要课题。本篇文章主要从建筑艺术哲学角度，分析了当今建筑创作的现状和特征，提出没有任何规范约束的个性创作自由，将使21世纪建筑创作思维充满活力与生机。     

我国建筑涂料技术进步简评

从以下诸方面简述我国建筑涂料的技术进步:⑴新品种涂料的研制开发;⑵加强对配套材料及施工技术的研究;⑶超细填料在涂料中的应用;⑷计算机自动配色技术;⑸产品标准的修订;⑹建筑涂料的实用范围扩大。     

An SS1-SS2 {beta}-barrel structure for the voltage-activated potassium channel

To examine the feasibility of a ß structure for thepore-lining region of the voltage-gated potassium channel, wehave characterized a family of 12 antiparallel ß-barrels.Each is comprised of four identical pairs of ß-strandsorganized with approximate 4-fold symmetry about a channel axis.The Cand N-termini of the ß-strand pairs are assumedto be at the extracellular end of the channel, and each pairis connected by a hairpin turn at the intracellular end of thechannel. The models differ in the residues located in the hairpinturn and in the orientation of the two strands of each pairin the barrel, i.e. whether the C-terminus of a pair is clockwise(CW) or counterclockwise (CCW) from the N-terminus when thechannel is viewed from outside the cell. Following known structureprecedents and potential energy predictions, the barrel is assumedto be right-twisting in all cases. All models have crowded layersof inward-projecting aromatic sidechains near the center ofthe channel which could regulate channel selectivity. The modelswith an odd number of amino acids in the hairpin turn have theadvantage of predicting that F433 points into the barrel, butthe disadvantage that V438 does not. Of these models, two ofthe models are most consistent with the external tetraethylanunonhim(TEA) block data, and of those, one (T439 CCW 3:5) is most consistentwith the internal TEA block data.     

借鉴德国,思考我国节能建筑设计

节约能源和保护环境是德国政府开发利用能源的一贯政策。德国特别重视建筑的节能,并收到了很好的效果,很多经验值得我们借鉴。从建筑节能设计角度分析,认为我国在建筑节能设计时,不应该简单复制节能建筑,应当变革现有的设计模式,从建筑的寿命周期着眼,系统运用高新技术,使建筑技术和建筑艺术相融合,并得到政府的支持。