New neural network-based response surface method for reliability analysis of structures

Neural Computing and Applications - In this paper, a new algorithm is introduced for reliability analysis of structures using response surface method based on a group method of data handling-type...     

Adolescents' Attachment Representations and Developmental Tasks in Emerging Adulthood.

The association between attachment representations and adolescents' coping with 3 developmental tasks of emerging adulthood-leaving home, advancing in the capacity for mature intimacy, and developing individuation-was examined. Israeli male adolescents (N = 88) were administered the Adult Attachment Interview during their high-school senior year. A year later, they and their friends reported on the adolescents' adjustment to mandatory military service. Three years later, participants and their parents reported on the adolescents' capacity for intimacy using an in-depth interview and on their individuation. An autonomous state of mind was associated with better coping with basic training and with a higher capacity for mature intimacy but was not associated with markers of individuation. The results highlight the importance of attachment representations in shaping an individual's developmental trajectory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Octa-O-bis-(R,R)-Tartarate Ditellurane (SAS) - a novel bioactive organotellurium(IV) compound: synthesis, characterization, and protease inhibitory activity

Octa-O-bis-(R,R)-Tartarate Ditellurane (SAS) is a new Te(IV) compound, comprised of two tellurium atoms, each liganded by four oxygen atoms from two carboxylates and two alkoxides of two tartaric acids. Unlike many other Te(IV) compounds, SAS was highly stable in aqueous solution. It interacted with thiols to form an unstable Te(SR)(4) product. The product of the interaction of SAS with cysteine was isolated and characterized by mass spectroscopy and elemental analysis. SAS selectively inactivated cysteine proteases, but it did not inactivate other families of proteolytic enzymes. It displayed selectivity towards the cysteine protease cathepsin B, a human enzyme of pharmaceutical interest, with a second order rate constant k(i)/K(i)=5900 M(-1) s(-1).     

Structural and Functional Changes and Possible Molecular Mechanisms in Aged Skin

Skin aging is a complex process influenced by intrinsic and extrinsic factors. Together, these factors affect the structure and function of the epidermis and dermis. Histologically, aging skin typically shows epidermal atrophy due to decreased cell numbers. The dermis of aged skin shows decreased numbers of mast cells and fibroblasts. Fibroblast senescence contributes to skin aging by secreting a senescence-associated secretory phenotype, which decreases proliferation by impairing the release of essential growth factors and enhancing degradation of the extracellular matrix through activation of matrix metalloproteinases (MMPs). Several molecular mechanisms affect skin aging including telomere shortening, oxidative stress and MMP, cytokines, autophagic control, microRNAs, and the microbiome. Accumulating evidence on the molecular mechanisms of skin aging has provided clinicians with a wide range of therapeutic targets for treating aging skin.     

Effect of Passage Number of Conditioned Medium Collected from Equine Amniotic Fluid Mesenchymal Stem Cells: Porcine Oocyte Maturation and Embryo Development

Oocyte in vitro maturation (IVM) is the most important first step in in vitro embryo production. One prerequisite for the success of IVM in oocytes is to provide a rich culture microenvironment that meets the nutritional needs of developing oocytes. We applied different equine amniotic fluid mesenchymal stem cell conditioned medium (eAFMSC-CM) from passages 7, 18, and 27 to porcine oocytes during IVM to determine its effects on oocyte development and subsequent embryo development, specifically. The eAFMSC-CM from passage 7 (eAFMSC-CMp7) has a considerable impact on 9 genes: BAX, BCL2, SOD2, NRF2, TNFAIP6, PTGS2, HAS2, Cx37, and Cx43, which are associated with cumulus cell mediated oocyte maturation. GSH levels and distribution of mitochondrial and cortical granules were significantly increased in oocytes incubated with eAFMSC-CMp7. In addition, catalase and superoxide dismutase activities were high after IVM 44 h with eAFMSC-CMp7. After in vitro fertilization, blastocyst quality was significantly increased in the eAFMSC-CMp7 group compared to control. Lastly, the antioxidant effect of eAFMSC-CMp7 substantially regulated the expression of apoptosis, pluripotency related genes and decreased autophagy activity in blastocysts. Taken together, this study demonstrated that the eAFMSC-CMp7 enhanced the cytoplasmic maturation of oocytes and subsequent embryonic development by generating high antioxidant activity.     

Graphene oxide reinforced chitosan/polyvinylpyrrolidone polymer bio‐nanocomposites

Bio‐nanocomposite films based on chitosan/polyvinylpyrrolidone (CS/PVP) and graphene oxide (GO) were processed using the casting/evaporation technique. It has been found that the three components of bio‐nanocomposites can be easily mixed in controlled conditions enabling the formation of thick films with high quality, smooth surface and good flexibility. Structural and morphological characterizations showed that the GO sheets are well dispersed in the CS/PVP blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and GO sheets thus improving their properties. It has been found that the water resistance of the CS/PVP blend is improved, and the hydrolytic degradation is limited by addition of 0.75 and 2 wt % GO. The modulus, strength, elongation and toughness of the bio‐nanocomposites are together increased. Herein, the steps to form new bio‐nanocomposite films have been described, taking the advantage of the combination of CS, PVP and GO to design the aforementioned bio‐nanocomposite films, which allow to have extraordinary properties that would have promising applications as eventual packaging materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41042.     

Electronic Level Structure and Single Electron Tunneling Effects in CdSe Quantum Rods

Optical spectroscopy and scanning tunneling microscopy are used to study the size and shape dependence of the electronic states in CdSe quantum rods. Samples having average rod dimensions ranging from 10 to 60 nm in length and 3.5 to 7 nm in diameter, with aspect ratios varying between 3 to 12, were investigated. Both size-selective optical spectroscopy and tunneling spectra on single rods show that the level structure depends primarily on the rod diameter and not on length. With increasing diameter, the band gap and the excited state level spacings shift to the red. The level structure is assigned using a multi-band effective-mass model. We shall also discuss the effect of single electron charging on the tunneling spectra, possibly reflecting the quantum rod level degeneracy, and its dependence on the tunneling junction parameters.     

A stabilizer for oscillating torques in synchronous machines

A novel torque stabilizer was developed and has been continuously applied at the Max-Planck-Institut fur Plasmaphysik (IPP), Garching, Germany, as a countermeasure to torsional oscillation and resonance problems in large synchronous machines. Such problems are most frequently encountered in rotor systems with long shafts and large inertias constituting a weakly damped mechanical resonator which exhibits a low resonance frequency, e.g., 10-30 Hz. This paper presents examples for the successful suppression of torsional resonances in synchronous machines of the IPP experimental power supply, an isolated power system based on flywheel generators. The novel torque stabilizer is a power electronic device which is connected to the stator winding of the synchronous machine. It produces the same effect as an increased natural damping for oscillation modes in the rotating shaft assembly. It is, therefore, universally applicable to torsional oscillation problems in generators and electrical drive systems.     

A Comprehensive Study on Physical,Mechanical, and Thermal Properties of Poly(Ethylene Terephthalate) Filled by Micro‐ and Nanoglass Flakes

Polyethylene terephthalate (PET) composites containing micro‐ and nanoglass flakes were prepared by melt blending. The percentage of nanoglass flakes was varied from 0.5, 1, 2, and 3 wt% and the concentration of microglass flakes was 1, 3, and 5 wt%. The effect of glass flake on morphology, physical, mechanical, and thermal properties of PET was studied using scanning electron microscopy (SEM), energy‐dispersive X‐ray analysis (EDXA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), X‐ray diffraction (XRD), and tensile test. The observations showed that both types of particles were dispersed in PET, homogeneously, though microglass flakes had better dispersion compared with their nanosized counterparts. According to DSC thermogram, the crystallization rate and temperature of PET increased with incorporation of both types of glass flakes. The crystallization rate of PET was increased from 31.41% to 34.25% with the addition of 1 wt% of nanoglass flakes. Moreover, the onset of thermal degradation increased more than 9°C with the addition of micro‐ and nanoglass flakes. Based on the mechanical viewpoint, the Young's modulus of PET was improved by the addition of both micro‐ and nanoglass flakes. On the other hand, the tensile strength of PET was decreased from 45.4 MPa to 31.3 MPa using 1 wt% of nanoglass flakes. According to X‐ray diffractometry, using of micro‐ and nanoglass flakes resulted in the decrement of PET crystallites. Whereas, the size of crystallites was lower than microglass flakes, in the case of using nanoglass flakes. J. VINYL ADDIT. TECHNOL., 26:380–389, 2020. © 2019 Society of Plastics Engineers     

Effect of epoxy resin on thermal,dynamic, and mechanical properties of rigid poly(vinyl chloride)

This work is concerned with the effect of an epoxy resin on the properties of rigid poly(vinyl chloride) (PVC). The epoxy resin concentrations of 0, 1, 2, 4, and 6 phr were used to prepare PVC/epoxy polymer blends and the viscoelastic behavior of the blends was investigated by dynamic mechanical thermal analysis and rheometry test. The results revealed that the low molecular weight epoxy resin did not greatly affect the viscoelastic properties of PVC. From the morphological point of view, the smallest droplet size of epoxy dispersed in the polymer blends was found in the sample with 1 phr epoxy resin, and the largest one was for the sample with 6 phr epoxy. The thermal properties of PVC/epoxy blends were investigated using differential scanning calorimetry and thermogravimetric analysis, as well. According to our research, the initial decomposition temperature of PVC was increased about 6°C by the incorporation of epoxy resin. The results of tensile test showed that the addition of epoxy resin decreased the elongation‐at‐break of PVC about 50% in the samples without calcium carbonate and about 25% in the samples containing calcium carbonate. Moreover, the failure mode of PVC was changed from a ductile fracture mode to a brittle fracture mode with the addition of epoxy resin. J. VINYL ADDIT. TECHNOL., 25:E72–E79, 2019. © 2018 Society of Plastics Engineers