An analogy between the spouted bed phenomena and the bubbling-to-spray transition

An analogy is drawn between the onset of minimum spouting and the bubbling-to-spray transition on a sieve tray to derive an analytical equation which relates the bed depth to the minimum air velocity required for the onset of spouting. The derived equation and the significance of the terms appearing in it are discussed and compared with existing correlations and the available data.     

Diffusion,convection and reaction in catalyst particles: analogy between slab and cylinder geometries

Forced intraparticle convection in a finite cylinder porous catalyst particle is studied. An analytical solution for steady state, simultaneous diffusion, convection and reaction is obtained and the effect of intraparticle convection on the catalyst performance, i.e. its effectiveness factor, is analysed. The relationship for the augmented intraparticle effective diffusivity and an equivalence ratio between the slab and the finite cylinder characteristic dimensions, valid in the whole range of Thiele modulus, are obtained.     

Structural and functional domains in human tumour necrosis factors

Human tumour necrosis factors (hTNFs) and ß are relatedpleiotropic cytokines which share many activities and competewith each other for binding to two receptor components on manycell types. Although structural and biological data indicatethat the active form of hTNF- may be a symmetrical trimer, themanner in which hTNFs interact with their receptors to triggera myriad of cell type-dependent responses is not clear. A combinationof chemical modification, epitope mapping and site-directedmutagenesis approaches suggest that at least four distinct peptidesequences are Important for the biological activity of hTNF-.In particular, certain peptide sequences between amino acidpositions 11 and 35 in hTNF- appear to be critical for receptorbinding and triggering biological responses. The recent cloningof the two hTNF-/ß receptors opens the way for precisemapping of the functional domains in hTNFs     

微囊藻毒素降解酶MlrA的结构功能分析

MlrA（亦称microcystinase）是微囊藻毒素（microcystins, MCs）细菌降解途径中负责催化起始反应的关键蛋白酶,其结构特征与底物水解机制尚未明确。使用折叠识别法构建MlrA分子模型,通过分子对接和定点突变分析了酶-底物的结合方式与相互作用,结合蛋白重组表达对酶活性影响机制等进行了探究。结果表明MlrA是定位于细菌细胞质膜的整合膜蛋白,主要由8个跨膜α-螺旋（TM1~8）组成,功能结构域ABI（TM4~7）形成向周质空间开放的底物反应空腔。MlrA催化残基（E172、H205、H260和N264）位于膜内,其侧链投射至反应腔内部。微囊藻毒素LR （MC-LR）采用β-发夹构型与酶结合并将易裂键暴露于水分子附近,其水解机制为E172和H205通过一般碱催化将水分子去质子化激活,对Adda-Arg肽键羰基碳进行亲核攻击;接着H260和N264构成氧阴离子穴以稳定过渡态氧阴离子;最后H205或E172催化胺离去基团发生质子化,使四面体氧阴离子中间体崩解。此外,MlrA不是金属蛋白酶,无法与金属离子（Ⅱ）配位结合,菲咯啉类化合物使酶分子发生非特异性解折叠而失活,EDTA对底物结合位点具有竞争作用。本研究揭示了MlrA的属性与水解机制,为进一步探索MCs微生物降解机理提供一定参考依据。     

Structural correspondence between music and color

The article outlines the features that are typical of the attempts to bridge between music and color on the artistic and scientific levels. It emphasizes the importance of clarifying the factors common to color and sound both for the purpose of understanding the communication codes of arts as well as for the development of syntax for expression in colors. The article adopts Gombreich's approach to investigate the connection between music and color through comparison of the relationships between the elements and not through comparison of the elements themselves. The article presents an experiment that examines how the organization of the sounds in a musical piece is expressed in color design: (1) How the overall impression of a piece of music is expressed in the choice of colors and in their reciprocal relationships; (2) What are the characteristics of color scales that were shaped according to a musical scale; and (3) What is the visual effect of a color scheme that was built according to the formation of notes of the musical piece.     

Structural and functional changes of silk fibroin scaffold due to hydrolytic degradation

In this study, hydrolytic degradation of silk fibroin (SF) in Phosphate buffer saline (PBS) after 12 weeks incubation was investigated. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X‐ray diffraction (XRD) patterns have confirmed the transition from crystalline β‐sheet to random coil in treated SF. A decrease in adhesion force and surface Young's modulus were observed using atomic force microscopy (AFM). Structural changes were further confirmed using scanning electron microscopy (SEM). Biocompatibility and alkaline phosphatase production of osteoblast cells were decreased significantly in treated SF scaffold. Moreover, a significant decrease in mRNA level of collagen type I and osteopontin compared with fresh SF scaffold was observed. Finally, structural and biological characteristics of SF scaffold could alter in PBS. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39980.     

Structural similarity and functional diversity in proteins containing the legume lectin fold

Knowledge of structural relationships in proteins is increasinglyproving very useful for in silico characterizations and is alsobeing exploited as a prelude to almost every investigation infunctional and structural genomics. A thorough understandingof the crucial features of a fold becomes necessary to realizethe full potential of such relationships. To illustrate this,structures containing the legume lectin-like fold were chosenfor a detailed analysis since they exhibit a total lack of sequencesimilarity among themselves and also belong to diverse functionalfamilies. A comparative analysis of 15 different families containingthis fold was therefore carried out, which led to the determinationof the minimal structural principles or the determining regionof the fold. A critical evaluation of the structural features,such as the curvature of the front sheet, the presence of thehydrophobic cores and the binding site loops, suggests thatnone of them are crucial for either the formation or the stabilityof the fold, but are required to generate diversity and specificityto particular carbohydrates. In contrast, the presence of thethree sheets in a particular geometry and also their topologicalconnectivities seem to be important. The fold has been shownto tolerate different types of protein–protein associations,most of them exhibiting different types of quaternary associationsand some even existing as complexes with other folds. The functionof every family in this study is discussed with respect to itsfold, leading to the suggestion that this fold can be linkedto carbohydrate recognition in general.     

Structural and Functional Differences between Homologous Bacterial Ribonucleases

Small cationic guanyl-preferring ribonucleases (RNases) produced by the Bacillus species share a similar protein tertiary structure with a high degree of amino acid sequence conservation. However, they form dimers that differ in conformation and stability. Here, we have addressed the issues (1) whether the homologous RNases also have distinctions in catalytic activity towards different RNA substrates and interactions with the inhibitor protein barstar, and (2) whether these differences correlate with structural features of the proteins. Circular dichroism and dynamic light scattering assays revealed distinctions in the structures of homologous RNases. The activity levels of the RNases towards natural RNA substrates, as measured spectrometrically by acid-soluble hydrolysis products, were similar and decreased in the row high-polymeric RNA >>> transport RNA > double-stranded RNA. However, stopped flow kinetic studies on model RNA substrates containing the guanosine residue in a hairpin stem or a loop showed that the cleavage rates of these enzymes were different. Moreover, homologous RNases were inhibited by the barstar with diverse efficiency. Therefore, minor changes in structure elements of homologous proteins have a potential to significantly effect molecule stability and functional activities, such as catalysis or ligand binding.     

Structural and functional role of lipids in yeast and mycelial forms ofCandida albicans

The levels of total lipids, sterols and phospholipids were found to be significantly higher in the mycelial form (log phase) ofCandida albicans than in the yeast form. Increased phospholipid levels in the mycelial form were due to higher levels of phosphatidylcholine, phosphatidylserine and phosphatidylinositol. Analyses of fatty acid composition also revealed higher levels of myristic acid (40%) in the yeast form, resulting in higher levels of saturated lipids than in the mycelial form. The changes in the lipid composition were also manifested in altered thermotropic phase behavior as gel-to-liquid crystalline phase transitions were observed at 36 and 27°C for the lipids of the yeast and mycelial forms, respectively. These changes coincided with higher uptake rate, i.e., Km and Vmax values, for the transport of L-proline and with a higher sensitivity of the mycelial form against antifungal drugs.     

Flow accelerates adhesion between functional polyethylene and polyurethane

Polyethylene (PE) has relatively poor adhesion with polar polymeric materials. In an effort to improve the adhesion between PE and thermoplastic polyurethane (TPU), maleic anhydride (MA), hydroxyl (OH), and secondary amine (NHR) functionalized PEs were blended into nonmodified PE. These functional groups will react with urethane linkages in TPU at the temperature of melt processing. We bonded these PEs to TPU via lamination and coextrusion. To compare the two processes, we determined the interfacial copolymer density Σ considering both advection and interfacial area generation. We found that the development of adhesion in coextrusion was much faster in comparison with lamination at the same temperature. This difference was attributed to the extensional and compressive flow in coextrusion overcoming the diffusion barrier at the interface and forcing reactive species to penetrate the interface. The effects of functional group reactivity and processing variables on adhesion were correlated with interfacial copolymer coverage. Amine functionalized PE showed dramatic adhesion improvement even at 1 wt %. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Structural identity between the iron- and manganese-containing superoxide dismutases

We have recently reported the first complete amino acid sequenceof an iron-containing superoxide dismutase. The iron enzymeis thought to be closely homologous to the manganese-containingsuperoxide dismutases. The availability of complete amino acidsequence information for four manganese superoxide dismutasesand the crystal structures for two iron and two manganese superoxidedismutases prompted us to investigate the degree of homologybetween the two proteins at various levels. We report that itis not possible to clearly distinguish the two proteins on thebasis of their secondary or tertiary structures. It would appearthat a small number of single site substitutions are responsiblefor conferring distinguishing properties between the two proteins.Substitution of glyclne 77 and glutamine 154 by a glutamineand an alanine respectively in Photobacterium leiognathi ironsuperoxide dismutase may distinguish the kinetic and other particularproperties of this protein from the manganese protein (and otheriron superoxide dismutases). Furthermore the primary structureof both the iron and manganese proteins does not appear to haveany homology with any other known amino acid sequence.     

Structural comparison between triglycerides and phospholipids from pig kidney

The compositional specificity of the major diacyl phosphatides, plasmalogens and triglycerides of pig kidney has been determined. The triglycerides have been shown to be esterified predominantly with saturated fatty acids in the 2 position while the phosphatides have predominantly unsaturated fatty acids in this position. Such complete “inversion” of the structure of triglycerides and phospholipids is not normally seen in mammalian tissue and suggests that the synthesis of structural polar lipids involves other steps than the reaction of a diglyceride with CDP-ethanolamine or CDP-choline. This marked difference in the fatty acid distribution of the polar lipids and triglycerides of the pig kidney may render this tissue especially suitable for studies on the turnover and synthesis of structural lipids.     

Structural materials underpinning functional materials: teaching old dogs new tricks

‘Structural’ polymers are finding new applications underpinning new technology developments based on functional polymers. This paper discusses the use of polyester films as base substrates for flexible electronic applications based on conjugated polymers and low‐temperature hydrogenated amorphous silica processing, and discusses the challenges involved in successfully developing substrates ‘fit for purpose’. Copyright © 2008 Society of Chemical Industry     

漂移赛车轮胎结构设计与刚性的相关性研究

以285/35ZR18 101W漂移赛车轮胎为例,研究漂移赛车轮胎结构设计与刚性的相关性。在轮胎上下胎侧部位增加增强层1和2,设计4种增强方案：方案一增强层1采用邵尔A型硬度为90度的胶片,增强层2采用467dtex/1×467dtex/1锦纶66帘布;方案二增强层1采用邵尔A型硬度为90度的胶片,增强层2采用2×0.30ST钢丝帘布;方案三增强层1采用2×0.30ST钢丝帘布,增强层2采用1670dtex/1芳纶＋1400dtex/1锦纶66混合帘布;方案四增强层1采用2＋2×0.25HT钢丝帘布,增强层2采用1680dtex/2芳纶帘布。测试结果表明：方案四轮胎的总接地压力及接地长度和宽度最大,接地印痕矩形率最小,趋于椭圆形;径向刚性和纵向刚性均最大,轮胎的承载能力和制动性能最好,有利于在极高速度下控制车辆的稳定性,满足高速、大角度甩尾等车辆操纵要求。     

Structural relationships between glycerides of pig serum and adipose tissue

Structural analyses have been performed on the triacylglycerols and phosphoglycerides isolated from adipose tissue, serum chylomicrons, and serum lipoproteins from pigs. The triacylglycerols from adipose tissue contained mainly palmitate esterified at the 2 position of the glycerol moiety, whereas those from the serum had predominately     

Structural relationship between thermomechanical history and strength of polymeric solids

Ultimate properties in polymeric solids strongly depend on thermomechanical history. We have shown that the polymer structure which depends on thermomechanical history can be quantitatively described by the relative amounts of enthalpy and entropy. The excess enthalpy decreases upon annealing and increases under the tensile stress. The increase in excess enthalpy reduces the relaxation time; thus a local brittle-to-ductile transition may be induced by stress concentration. It follows that in a well-annealed material, this transition is more difficult to induce. Effects of molecular weight and orientation are also discussed in terms of dissipation of strain energy as the condition required for the strength of polymeric solids.     

Engineering detonation nanodiamond - Polyaniline composites by electrochemical routes: Structural features and functional characterizations

Novel detonation nanodiamond (DND) - polyaniline (PANI) composite systems have been prepared by electrochemical polymerization techniques. Thanks to the use of two different electrochemical methods, i.e. cyclic voltammetry and chronoamperometry, it has been possible to emphasize the influence of DND particles on the nucleation mechanism of the conducting polymer. In particular, the presence of DND into the reaction environment has proven to modulate the organization of the aniline oligomers into π-stacked aggregates and to induce the production of one-dimensional nanostructures. Scanning and transmission electron microscopy was used to investigate the morphology of the final composites. The protonated conducting form of the PANI matrix has been evidenced by Raman spectroscopy and the ionic/electronic transport of the PANI-DND systems was tested by means of electrocatalysis measurements toward the iodine/iodide redox couple. Based on the present experimental data, the use of nanodiamond as filler for conducting polymer based nanocomposite represents not only a fascinating challenge for the production of advanced technological applications but it can also be exploited for the controlled growth of polymeric units and for the fabrication of tailored polymeric architectures.