含有基体开裂和内部分层的复合材料层板的刚度特性

本文分析了复合材料层板中两种类型的损伤,一种是层内损伤卽基体开裂,另一种是层间损伤卽内部分层。文中取损伤向量作为唯象理论的内部状态变量,确定了这两种损伤的强度与全部刚度系数之间的关系。分析表明,层内开裂损伤不僅使得材料弹性模量下降而且还改变了层板的初始正交異性对称性;层间分层损伤不改变层板初始正交異性对称性但使得弹性模量降低。应用本文分析方法对几种层板的模量变化进行了预算,并同实验结果进行了比较,发现两者之间吻合得很好。     

Functionalized core-shell nanostructures with inherent magnetic character: Outperforming candidates for the activation of PMS

With a view to engender an advanced oxidation protocol, in the present investigation a very efficient and outperforming catalytic system has been developed which employs peroxymonosulphate (PMS) as oxidant and surface metal functionalized core-shell nanostructures (with ferrite as core coated with shell of dopamine and surface functionalized with transition metal nanoparticles) as catalysts. The present protocol bids fast and facile degradation of organic pollutants without the aid of any promoting radiations. Every component of the developed core-shell nanostructures (M@Dop@CoFe; M?=?Cr, Mn, Fe, Co, Ni, Cu and Zn) has been found to contribute synergistically in the overall oxidative-degradation process. Co@Dop@CoFe presented the best results for the oxidative-degradation of nitrophenols (NP) taken as model pollutants with rate constant values of 8.13?×?10^?1?min^?1, 3.56?×?10^?1?min^?1 and 17.15?×?10^?1?min^?1 for 2-NP, 3-NP and 4-NP respectively. The synthesized core-shell nanocatalysts have been established to be leach-proof and recyclable to a very good extent.     

Modeling of Wrinkling in Sandwich Panels under Compression

A wrinkling model for sandwich panels in compression is developed with the assumption of a continuous isotropic linear elastic core. Wrinkling stresses for the three modes, defined in a well-known book by H. G. Allen, are expressed by a unified, single expression. The expression depends linearly on a case parameter η, defined to specify the three cases of wrinkling: η = 0 for single-sided face wrinkling (case 1), η = 1 for in-phase wrinkling (case 2), and η = ?1 for out-of-phase wrinkling (case 3). It is shown that the stresses in all three cases are almost identical for short wavelength wrinkling and can be expressed by a single simplified analytical expression; however, they may differ significantly in moderate and long wavelength wrinkling, and for these cases they are given by simplified analytical expressions. It is proved that the in-phase wrinkling stress is the lowest among the three cases. Based on the analysis conducted, limitations of the commonly used Winkler and two-parameter models are discussed. Finally, engineering design procedures are recommended for the wrinkling effect in sandwich panels under compression.     

In vitro toxicity study of plant latex capped silver nanoparticles in human lung carcinoma cells

Organically modified silver nanoparticles were prepared by biosynthetic route induced by stem latex of a medicinally important plant, Euphorbia nivulia. The reduction and stabilization is assisted by certain peptides and terpenoids present within the latex. The aqueous formulation of latex capped silver nanoparticles (LAgNPs) being completely free of toxic chemicals can be directly used for administration/in vivo delivery of nanoparticles. The in vitro cytotoxicity evaluation of the latex capped nanoparticles was carried out using human lung carcinoma cells (A549) by MTT cell viability assay. Further, possible cytotoxic mechanisms were evaluated using various biomarkers for cytotoxicity and oxidative stress viz. extracellular lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) generation, intracellular reduced glutathione (GSH), malondialdehyde (MDA), superoxide generation and acridine orange/ethedium bromide staining. It can be concluded from the present study that LAgNP formulation is toxic to A549 cells in a dose dependent manner. Thus plant latex solubilizes the AgNPs in water and acts as a biocompatible vehicle for transport of AgNPs to tumor/cancer cells.     

Compartmentalization Role of A-Kinase Anchoring Proteins (AKAPs) in Mediating Protein Kinase A (PKA) Signaling and Cardiomyocyte Hypertrophy

The Beta-adrenergic receptors (β-ARs) stimulation enhances contractility through protein kinase-A (PKA) substrate phosphorylation. This PKA signaling is conferred in part by PKA binding to A-kinase anchoring proteins (AKAPs). AKAPs coordinate multi-protein signaling networks that are targeted to specific intracellular locations, resulting in the localization of enzyme activity and transmitting intracellular actions of neurotransmitters and hormones to its target substrates. In particular, mAKAP (muscle-selective AKAP) has been shown to be present on the nuclear envelope of cardiomyocytes with various proteins including: PKA-regulatory subunit (RIIα), phosphodiesterase-4D3, protein phosphatase-2A, and ryanodine receptor (RyR2). Therefore, through the coordination of spatial-temporal signaling of proteins and enzymes, mAKAP controls cyclic-adenosine monophosphate (cAMP) levels very tightly and functions as a regulator of PKA-mediated substrate phosphorylation leading to changes in calcium availability and myofilament calcium sensitivity. The goal of this review is to elucidate the critical compartmentalization role of mAKAP in mediating PKA signaling and regulating cardiomyocyte hypertrophy by acting as a scaffolding protein. Based on our literature search and studying the structure–function relationship between AKAP scaffolding protein and its binding partners, we propose possible explanations for the mechanism by which mAKAP promotes cardiac hypertrophy.     

Waste fly ash–ZnO as a novel sunlight-responsive photocatalyst for dye discoloration

Treating waste with a waste material using freely available solar energy is the most effective way towards sustainable future. In this study, a novel photocatalyst, partly derived from waste material from the coal industry, was developed. Fly ash hybridized with ZnO (FA—Zn) was synthesized as a potential photocatalyst for dye discoloration. The synthesized photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and ultraviolet—visible/near infra-red spectroscopy. The photocatalytic activity was examined with the discoloration of methylene blue used as synthetic dye wastewater. All the experiments were performed in direct sunlight. The photocatalytic performance of FA—Zn was found to be better than that of ZnO and the conventionally popular TiO₂. The Langmuire—Hinshelwood model rate constant values of ZnO, TiO₂, and FA—Zn were found to be 0.016 min^-1, 0.017 min^-1, and 0.020 min^-1, respectively. There were two reasons for this: (1) FA—Zn was able to utilize both ultraviolet and visible parts of the solar spectrum, and (2) its Brunauere—Emmette—Teller surface area and porosity were significantly enhanced. This led to increased photon absorption and dye adsorption, thus exhibiting an energy-efficient performance. Therefore, FA—Zn, partly derived from waste, can serve as a suitable material for environmental remediation and practical solar energy applications.     

Synthesis of Benzenesulfonamide Derivatives via Ring Opening of Aziridines in the Presence of Magnetically Retrievable Graphene Based (CoFe@rGO) Nanohybrid

Graphene based magnetic nanohybrids have engrossed considerable research curiosity because of their exceptional properties and diverse applications associated with green chemistry. In this regard, a practical, facile and regioselective preparation of 1,2-diamines from N-tosylaziridine/(S)-(+)-2-Benzyl-1-(p-tolylsulfonyl)aziridine and aryl amines in the presence of magnetically separable graphene based nanohybrid (CoFe@rGO) has been proposed under mild and solvent free conditions. The FT-IR, FE-SEM, XPS, XRD and TEM spectroscopic analysis confirmed the formation of the CoFe@rGO nanohybrids. For unsymmetrical aziridine, nucleophilic attack of aryl amines was observed to take place selectively at the more substituted carbon atom of aziridine ring. Environmentally benign, efficient, shorter reaction time, solvent-free conditions, low catalyst loading, excellent reaction yields and reusability of the catalyst for six consecutive runs without significant loss in its activity are the key advantages of this protocol.

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