The study of welded semi‐rigid connections in fire

Considering the deterioration of steel properties by temperature increase and the importance of the influence of connection behavior on the behavior of steel structures, we find that the exact understanding of the behavior of a specific steel connection in fire as well as the information about the effect of fire on the principal constitutive characteristics of the connection is necessary for safe design against fire. Thus, in this paper, the behavior of welded angle connections is studied at elevated temperatures using the abaqus finite element software. Steel members and connection components are considered to behave nonlinearly; the degradation of steel properties with increasing temperature is considered according to EC3, BS5950 recommendations. The results of finite element and experimental tests conducted on welded angle connections are compared, and the obtained failure modes and moment–rotation–temperature characteristics are in good agreement with those associated with the experimental tests. In the following, since the knowledge about moment–temperature–rotation behavior of a specific connection is needed for a fire‐resistant design, these properties are accurately determined, and finally, the effect of some parameters such as the moment applied on beam, change of column axial force and change of beam shear force on the stiffness of these connections at elevated temperatures is determined. Copyright © 2011 John Wiley & Sons, Ltd.     

An ambipolar polymer additive for enhanced open circuit voltage in a bulk heterojunction solar cells

Open circuit voltage (V_OC) of organic bulk heterojunction solar cell is extended by the addition of a 20 wt % of F8TBT, an ambipolar polymer in the active layer matrixes (P3HT:PCBM) and then spin casted (1000 rpm/30 s) in the optimized devices on the PEDOT:PSS layer of the ITO glass. A substantial increase in the open circuit voltage from approximately 0.61–0.88 V (44.26%) has been observed with slight increase in efficiency up to 1.91% in the fabricated devices. However, further increment of F8TBT content to 40 wt % reduces the photovoltaic efficiency and affects the J_SC values remarkably, possibly due the excess amount of resistance developed. The enhancement of V_OC is attributed to the ambipolar nature of F8TBT polymer which facilitates the generated electron and hole transfer at the respective electrodes, enhanced π–π* conjugation in polymer matrix, a superior nanoscale separation, and better molecular conformation at the film interface, thus giving an ample opportunities to explore the impact of blending of materials rather than depositing a thin buffer layer by expensive vapor phase technologies. The details of electrical and microstructure characterization of the film were analyzed by AFM, SEM, UV–Vis, J–V characteristics, and EQE techniques. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43042.     

Simultaneous control of rod length and pore diameter of SBA-15 for PPL loading

Mesoporous silica materials are attractive materials for immobilizing enzymes because of their well-ordered structures, large surface area are pore volume. Diffusion of large enzyme molecules such as porcine pancreatic lipase (PPL) through the lengthy channels of MPS takes place too slowly. Therefore, the squat of the enzyme at the pore mouth entrance, actually makes the rest of the channel useless. In this study, to overcome this problem, synthesis parameters of SBA-15 were changed, since along with pore diameter increasing, the mesochannel length becomes shorter. The main point to obtain a well-ordered 2D hexagonal pore structure was the pre-hydrolysis of tetraethyl orthosilicate (TEOS) before the addition of 1,3,5-trimethyl benzene as a micelle swelling agent. Due to the strong effect of zirconium in changing the morphology of SBA-15 particles, we modified SBA-15 in the presence of a small amount of ZrOCl₂ in the synthesis solution under acidic conditions. As a result, mesochannel length of SBA-15-Zr was shortened from 600 to <200 nm. The morphology of mesoporous silica was also changed from rod-like to platelet, because of the accelerating effect of Zr(IV) on the self-assembly rate of P123 and TEOS condensation. Characteristic results conducted by low angle XRD, high resolution transmission electron microscopy and nitrogen adsorption, confirmed tuning effect of Zr(IV) in SBA-15. Furthermore, it was shown that the number of pore entrances increases with decreasing the length of SBA-15 mesochannels, leading to obvious improvement of enzyme uptake. PPL has been successfully immobilized in the mesoporous channels of SBA-15-Zr. The total amount of lipase adsorbed on the mesoporous SBA-15-Zr was measured by thermal gravimetric analysis. The largest PPL adsorption capacity was 784 mg/g belonging to the SBA-15-Zr with the length of 150 nm and the mean pore size diameter of 9.22 nm.     

Carbon nanotubes growth on sub-surface catalyst layer of Cu–Ni nanoparticles thin film

Cu–Ni nanoparticles (NPs) thin films were prepared by Direct Current (DC) magnetron sputtering with Cu and Ni targets. The products were used as catalysts for Thermal CVD (TCVD) growing of carbon nanotubes (CNTs) from acetylene gas at 825°C. In order to characterize the nano catalysts, X-ray Diffraction (XRD) and Atomic Force Microscopy (AFM) and to study the synthesized CNTs Scanning Electron Microscopy (SEM) and Raman Spectroscopy were applied. A remarkable CNT grown on the sub-surface of catalyst layer compared to its top is deduced from SEM images. Despite the poor catalytic activity of the top-surface, these considerations led us to conclude more catalytic activity of the sub-surface.     

Fabrication of protective-coated SiC reinforced tungsten matrix composites with reduced reaction phases by spark plasma sintering

SiC reinforced tungsten matrix composites were fabricated via the spark plasma sintering process. In order to prevent an interfacial reaction between the SiC and tungsten during sintering, TiOx coated SiC particles were synthesized by a solution-based process. TiOx layer coated SiC particles were treated in high temperature nitriding conditions or annealed in a high temperature vacuum to form TiN or TiC coated SiC particles, respectively. The TiC layers coated on SiC particles successfully prevented tungsten from reacting with SiC; hence the proposed process resulted in successful fabrication of the SiC/W composites. The mechanical properties such as compressive strength and flexural strength of the composites were measured. Additionally, the effect of SiC on the high temperature oxidative ablation of tungsten was also investigated. The addition of SiC resulted in an improved oxidative ablation resistance of the tungsten-based composites.     

Bioaugmentation of floating treatment wetlands for the remediation of textile effluent

This pilot study evaluated the effects of bacterial augmentation on the efficiency of floating treatment wetlands (FTWs) to remediate textile wastewater. Two wetland plants, Phragmites australis and Typha domingensis, were used to develop FTWs, which were then augmented with a bacterial consortium of three strains (Acinetobacter junii, Pseudomonas indoloxydans, and Rhodococcus sp.). Results showed that both plant species removed colour, organic matter, toxicity, and heavy metals from textile wastewater and their removal efficiency was further enhanced by augmentation with bacteria. The maximum removal efficiencies of colour, COD and BOD after an 8‐day period were 97, 87 and 92%, respectively, by FTWs carrying P. australis inoculated with the bacterial consortium. Furthermore, the same combination showed 87–99% reduction of heavy metals in the textile wastewater as well. These results indicate that FTWs can be used for the treatment of textile effluent and their working efficiency can be improved by plant‐bacterial synergism.     

Carbon nanotubes‐filled thermoplastic polyurethane–urea and carboxylated acrylonitrile butadiene rubber blend nanocomposites

This article reports the preparation and characterization of multiwalled carbon nanotubes (MWCNTs)‐filled thermoplastic polyurethane–urea (TPUU) and carboxylated acrylonitrile butadiene rubber (XNBR) blend nanocomposites. The dispersion of the MWCNTs was carried out using a laboratory two roll mill. Three different loadings, that is, 1, 3, and 5 wt % of the MWCNTs were used. The electron microscopy image analysis proves that the MWCNTs are evenly dispersed along the shear flow direction. Through incorporation of the nanotubes in the blend, the tensile modulus was increased from 9.90 ± 0.5 to 45.30 ± 0.3 MPa, and the tensile strength at break was increased from 25.4 ± 2.5 to 33.0 ± 1.5 MPa. The wide angle X‐ray scattering result showed that the TPUU:XNBR blends were arranged in layered structures. These structures are formed through chemical reactions of ? NH group from urethane and urea with the carboxylic group on XNBR. Furthermore, even at a very low loading, the high degree of nanotubes dispersion results in a significant increase in the electrical percolation threshold. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40341.     

Flammability and thermal properties of epoxy/glass/MWNT Composites

The aim f this work is to study the effect of nanotubes on flammability properties of epoxy/glass composites. Multiwalled carbon nanotubes (MWNT) and its functionalized derivative (amino functionalized nanotubes) were incorporated into epoxy resin. To disperse MWNTs in the epoxy resin, different ways were employed. Microscopic observations showed that, the best dispersion state was gained by using ultrasonication method and high shear flow simultaneously. Thermal resistance of cured epoxy resins containing various amounts of nanotubes (0.25–0.7 wt %), was investigated by thermo gravimetric analysis (TGA). Introducing MWNTs and amino‐MWNTs to samples increased the initial thermal decomposition temperature for about 32 and 37°C, respectively. LOI measurements of composite samples showed an increase up to 32. Cone calorimetry test was carried out on epoxy/glass and epoxy/glass containing 0.5% MWNT. The results showed that, introducing 0.5% MWNTs decreases maximum average rate of heat emission for about 26%. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39849.     

Molecular Cross-Talk between Gravity- and Light-Sensing Mechanisms in Euglena gracilis

Euglena gracilis is a photosynthetic flagellate. To acquire a suitable position in its surrounding aquatic environment, it exploits light and gravity primarily as environmental cues. Several physiological studies have indicated a fine-tuned relationship between gravity sensing (gravitaxis) and light sensing in E. gracilis. However, the underlying molecular mechanism is largely unknown. The photoreceptor photoactivated adenylyl cyclase (PAC) has been studied for over a decade. Nevertheless, no direct/indirect interaction partner (upstream/downstream) has been reported for PAC. It has been shown that a specific protein, kinase A (PKA), showed to be involved in phototaxis and gravitaxis. The current study reports the localization of the specific PKA and its relationship with PAC.