The Application of Different Physical Approaches for The Description of Structural Features in Wheat and Rye Starches. A DSC Study

Starches isolated from wheat (Rapoport's variety) at different stages of maturation and from completely maturated rye (Viatka‐2 variety) were investigated in excess of water and in 0.6 M KCl using high sensitivity differential scanning microcalorimetry (HSDSC). Applying some physico‐chemical approaches, the starch polymorphous structure, the thickness of the crystalline lamellae and the thermodynamic parameters characterizing their surface faces were determined. It has been established that wheat and rye starches belong to the A‐type starches. It is suggested that during biosynthesis of granules the formation of the A‐type structure is accompanied by an accumulation of crystal defects. This process leads to a decrease in the melting temperature of starches.     

不同结合体系刚玉基浇注料的脱水行为

分别将水合结合、水合+凝聚结合、凝聚+水合结合和凝聚结合的刚玉基浇注料成型和室温下养护后称量,再依次称量110℃干燥后以及从200℃开始每间隔100℃至1000℃热处理后的质量,以质量损失和变化快慢来反映浇注料在养护和加热过程中的脱水行为。借助XRD、TG和DTA对各浇注料基质浆体的脱水行为和相组成进行分析。浇注料的脱水可分为剧烈、平缓和完成3个阶段。水合结合主导的水泥结合的浇注料和低水泥浇注料的脱水相似,3个脱水阶段分别为室温～300℃、300～600℃和600℃以上。以凝聚结合主导的二氧化硅微粉和水合氧化铝结合的浇注料、MgO-SiO2-H2O结合的浇注料及超低水泥浇注料的脱水行为相似,3个脱水阶段分别为室温～110℃烘干、110～400℃和400℃以上。     

Structural modification of polyisophthalamides by incorporating dimethylaminoazobenzene pendent groups

Certain structurally modified polyisophthalamides with bulky azo pendent groups were prepared from the polycondensation of 5-(4′-dimethylaminoazobenzene) isophthaloyl chloride with various aromatic diamines. The corresponding unmodified polyisophthalamides were also synthesized to compare their properties. The modified polyisophthalamides showed higher solubility in certain solvents, such as 1,4-dioxane, m-cresol, cyclohexanone, and CCl₃COOH, than the parent polyamides. The hydrophilicity of the modified polyisophthalamides was estimated by water absorption measurements, and it was found to be significantly higher than that of the corresponding unmodified counterparts. The modified polyisophthalamides were crosslinked upon heat curing, and they were stable up to 340–374°C in N₂ or air and afforded anaerobic char yields of 68–72% at 800°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 921–930, 1997     

Superstructures of Self‐Organizing Thiophenes

The self‐assembling properties of π‐conjugated oligo‐, poly‐, and cyclothiophenes (see Figure) have been studied with different techniques. Scanning tunneling microscopy on perfectly ordered two‐dimensional monolayers at the solution–HOPG (highly oriented pyrolytic graphite) interface has successfully been applied. The submolecular resolution achieved in the STM images provides valuable lattice and molecular information. Supported by X‐ray structure analyses of the 3D bulk material and by theoretical calculations, molecular conformations, molecule–molecule, and molecule–substrate interactions of the oligo‐, poly‐, and cyclomers have been analyzed and discussed.     

系留气球系统牵引绞盘结构设计及其力学分析

针对承受系留气球系统主要载荷的牵引绞盘缺乏设计理论依据的问题,阐述了牵引绞盘张力释放原理。采用微分法和叠乘法,构建了绞盘的力学模型,得到了张力衰减的规律和数学方程,分析了缆绳张力的衰减系数。结果表明:缆绳张力衰减的效果只与缆绳总包角α、当量摩擦因数μ以及离心张力Tc有关;α和μ越大,张力衰减效果越好,但过大的α和μ会降低缆绳寿命,加剧绞盘承载不均;较大的Tc会降低衰减效果,但有利于绞盘均衡承载;合理的衰减系数有利于缆绳张力释放均匀。根据分析结果,完成了绞盘的结构设计与有限元仿真,对牵引绞盘的设计具有一定的工程指导价值。     

Assessment of the structural factors controlling the enzymatic saccharification of rice straw cellulose

In this study, the structural factors controlling the enzymatic saccharification of rice straw cellulose were examined by preparing structure-modified rice straw samples such as dewaxed, alkali-treated, oxidized, and swollen rice straw. It was found that the initial enzymatic saccharification rate of the various structure-modified samples was largely controlled by the initial cellulose surface area of the cellulose unit. Although the presence of lignin limited the cellulose surface area, there was no strong relationship between the lignin content and the initial reaction. On the other hand, the long-term enzymatic saccharification of rice straw cellulose highly depended on the lignin removal rate (lignin content). It was also found that silica is not a crucial factor in controlling the enzymatic saccharification.     

Evaluating accidents in the offshore drilling of petroleum: Regional picture and reducing impact

This study examined several accidents over the last 56 years in the offshore drilling of petroleum. The aim is to examine the situation in relation to jack-ups, drill ships, semi-submersible and platforms and have a better awareness and understanding which may reduce the number of accidents. The materials examined were available published reports and data on exploration and production activities. From 219 accidents recorded the highest was due to blowouts with 46.1%, followed by storms and hurricanes with 15.1% and structural failures with 11.4%. High fatalities occurred at the Funiwa 5 platform in Nigeria with 230, the Piper Alpha platform in the North Sea with 167 and the Keilland semi-submersible in Norway. Other high fatalities were recorded at the Ocean Ranger fire and sinking, Java Sea sinking, Bohai 2 and Bohai 3 fire and sinking. Worker training and discipline must be maintained at a high level. The facilities must be kept sea-worthy and reliable through regular maintenance.     

Performance-based analysis of cylindrical steel containment Vessels exposed to fire

This paper reports the results of a numerical investigation on the structural safety assessment of a nuclear cylindrical steel containment vessel exposed to an accidental external fire condition. A coupling procedure is proposed, linking the modeling of a nearly compressible flow with input energy given by a combustion model (CFD model) and a structural thermo-mechanical analysis (FEM model), allowing an accurate evaluation of a fluid-thermo-mechanical response for the entire duration of the simulated accident. The time-temperature evolution of the burned gases, resulting from the combustion of a hydraulic leakage pool, is performed by the CFD model. The FEM model is used to obtain (i) temperature variation and, (ii) thermo-mechanical behavior and ultimate strength of the vessel. The obtained results indicate that the suggested methodology can provide reliable fire-safety analyses, ensuring that the main safety (load-bearing and containment) functions of the installation are not impaired during accidental events.     

Unified quality assessment of natural and screen content images via adaptive weighting on double scales

In multimedia communication systems, digital images may contain various visual contents, among which the natural scene images (NSIs) and screen content images (SCIs) are two important and common types. The existing full-reference image quality assessment (IQA) metrics are designed for only one type of images, but cannot precisely perceive the visual quality of another type. It is still unclear what the different characteristics are between NSIs and SCIs resulting in this failure. Inspired by some psychological studies, we figure out that it is due to the different structural scale levels between NSIs and SCIs. Given this observation, this paper introduces the gradient degradation of Gaussians (GDoG) to analyze the images’ structural scale level, proposes a fast unified IQA index for both NSIs and SCIs by incorporating an adaptive weighting strategy on double scales. Experimental results conducted on several databases verify the effectiveness and efficiency of the proposed unified IQA index for both types of images, also demonstrate that the adaptive weighting strategy based on GDoG can improve the existing models for cross-content-type images.