Residual stress development in Pb(Zr,Ti)O3/ZrO2/SiO2 stacks for piezoelectric microactuators

The residual stress of multilayers in piezoelectric microelectromechanical systems structures influences their electromechanical properties and performance. This paper describes the development of residual stress in 1.6 μm Pb(Zr_0.52,Ti_0.48)O₃ (PZT)/0.3 μm ZrO₂/0.5 μm SiO₂ stacks for microactuator applications. The residual stresses were characterized by wafer curvature or load-deflection measurements. PZT and zirconia films were deposited on 4-in. (100) silicon wafers with 0.5 μm thick thermally grown SiO₂ by sol–gel processes. After the final film deposition, the obtained residual stress of PZT, ZrO₂, and SiO₂ were 100–150, 230–270, and − 147 MPa, respectively. The average stress in the stack was  80 MPa. These residual stresses are explained in terms of the thermal expansion mismatch between the layers and the substrate. Load-deflection measurements were conducted to evaluate localized residual stresses using released circular diaphragms. The load-deflection results were consistent with the average stress value from the wafer curvature measurements. It was found that more reasonable estimates of the stack stresses could be obtained when mid-point vertical deflection data below 6 μm were used, for diaphragms 0.8–1.375 mm in diameter.     

Potential of biohydrogen generation using the delignified lignocellulosic biomass by a newly identified thermostable laccase from Trichoderma asperellum strain BPLMBT1

Delignification of plant-based biomass is one of the most important steps to determine the commercial success of bioavailability, and enzymatic delignification mediated via laccases could significantly improve the yield in an eco-friendly and precise manner. In this study, an extracellular laccase is newly identified and characterized from Trichoderma asperellum strain BPLMBT1. The purified laccase with specific activity of 51.0 U/mg, possesses a molecular mass of 65.0 kDa with absorbance peaks of 610–630 and 330 nm in the UV–Vis spectrum indicating the presence of the inclusive types I and III copper catalytic centers. The wide thermal and pH stability of this laccase, with optimal temperature of 80 °C and 3.0, are demonstrated by biochemical characterization and kinetics determination. In addition, the delignification of sweet sorghum stover biomass by the purified laccase resulting in an optimal lignin removal of 76.93% reveals its potential of utilizing delignified biomass for biohydrogen production 402.01 mL of biohydrogen was achieved after 84 h of anaerobic fermentation, which is 3.26-fold higher than the control without enzymatic pretreatment. The overall outcomes demonstrate an efficient way to utilize the thermostable laccase for biofuels conversion from lignocellulosic biomass.     

Feature interaction in a federated communications-enabled collaboration platform

Existing online collaboration tools and platforms provide basic communications integration and the ability to include some real-time information sources. Moreover, users prefer to be able to choose which collaboration tool they use for a given interaction, and over the course of long-term collaboration, will typically use a variety of tools, including email, instant messages, wikis, blogs, web conferences, and shared documents.     

A Probabilistic Method to Predict Fatigue Crack Initiation

A probabilistic method to predict macrocrack initiation due to fatigue damage is presented in this paper. Acoustic non-linearity is used to quantify pre-macrocrack initiation damage. This data is then used in a probabilistic analysis of fatigue damage. The probabilistic fatigue damage analysis consists of a suitably chosen damage evolution equation to model accumulated damage coupled with a procedure to calculate the probability of macrocrack initiation. The probability of macrocrack initiation is evaluated using the Monte Carlo Method with Importance Sampling. Numerical results for the probabilistic assessment of fatigue damage for a sample problem are presented and compared with experimental results.     

CFD Simulation of Mass Transfer Efficiency and Pressure Drop in a Structured Packed Distillation Column

The pressure drop and mass transfer efficiency for two‐phase flow in a structured packed column were simulated using a commercial CFD package, CFX version 10. The distillation of the methanol/isopropanol system was carried out in a 0.073 m diameter column, with an element composed of a ceramic structured packing and 0.053 m in height. The Height Equivalent to Theoretical Plate (HETP) value varied from 0.106–0.146 m. Pressure drop experiments were measured with an air/water system. The pressure drops at the flooding and loading points were ca. 173 and 580 Pa/m of packing, respectively. HETPs and pressure drops calculated from the Computational Fluid Dynamics (CFD) model were compared to their experimental counterparts. The average relative error between CFD predictions and the experimental data for the prediction of dry pressure drop, irrigated pressure drop and mass transfer efficiency are 20.3 %, 23 % and 9.15 %, respectively. In all cases, the CFD predictions show a good agreement with the experimental data, indicating that CFD is a reliable, cost saving and suitable technique for the design and optimization of separation processes.     

Electrospun polyvinyl alcohol membranes incorporated with green synthesized silver nanoparticles for wound dressing applications

Electrospun membranes have the potential to act as an effective barrier for wounds from the external environment to prevent pathogens. In addition, materials with good antibacterial properties can effectively fight off the invading pathogens. In this paper, we report the development of a novel electrospun polyvinyl alcohol (PVA) membrane containing biosynthesized silver nanoparticle (bAg) for wound dressing applications. Plant extract from a medicinal plant Mimosa pudica was utilized for the synthesis of bAg. Synthesized bAg were characterized by Ultraviolet-Visible (UV) Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of bAg was obtained from Transmission Electron Microscopy (TEM) and found that they were spherical in morphology with average particle size 7.63?±?1.2?nm. bAg nanoparticles incorporated PVA membranes were characterized using several physicochemical techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD) analysis. Experimental results confirmed the successful incorporation of bAg in PVA fibers. PVA nanofiber membranes incorporated with bAg showed good mechanical strength, excellent exudate uptake capacity, antibacterial activity, blood compatibility and cytocompatibility.

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Analysis of Pseudomonas aeruginosa PAO1 Lipid A Changes During the Interaction with Model Organism,Caenorhabditis elegans

Lipopolysaccharide (LPS) is the main surface constituent of Gram-negative bacteria. Lipid A, the hydrophobic moiety, outer monolayer of the outer cell membrane forms the major component of LPS. Immunogenic Lipid A is recognized by the innate immune system through the TLR 4/MD-2 complex. Pseudomonas aeruginosa PAO1, a Gram-negative bacterium is known to cause nosocomial infection and known for its adaptation to adverse environmental conditions. Pseudomonas aeruginosa can infect a broad host spectrum including Caenorhabditis elegans, a simple free living soil nematode. Here, we reveal that PAO1 modifies its Lipid A during the host interaction with C. elegans. The penta-acylated form of Lipid A was identified by using matrix assisted laser desorption ionization–time of flight analysis and the β-(1,6)-linked disaccharide of glucosamine with phosphate groups, 2 and 2′ amide linked fatty acid chain and 3 and 3′ ester linked fatty acids were investigated for the modification using the non destructive ¹H NMR, spin–lattice (T ₁) relaxation measurement, differential scanning calorimetry. T ₁ relaxation measurements showed that the 2 and 2′ amide linked fatty acid chain, –CH in the glucosamine disaccharide of PAO1 lipid A, in an exposed host had a different spin lattice relaxation time compared to an unexposed host and the findings were reconfirmed using in vitro human corneal epithelial cells cell lines. Furthermore, scanning electron microscope and confocal laser scanning microscopy analysis revealed that the P. aeruginosa PAO1 biofilm formation was disturbed in the exposed host condition. The daf-12, daf-16, tol-1, pmk-1, ins-7 and ilys3 immune genes of C. elegans were examined with live bacterial and isolated lipid moiety infection and the expression was found to be highly specific. Overall, the present study revealed that PAO1 modified its 2 and 2′ amide linked fatty acid chain in the lipid A of PAO1 LPS during the exposed host condition.     

Wettability and In Vitro Bioactivity Studies on Titanium Rods Processed by Equal Channel Angular Pressing

Commercial purity titanium (CP-Ti) was processed by equal channel angular pressing (ECAP) with a channel angle of 120° with the aim of studying the effect of microstructure on the wettability and bioactivity. Solid and tubular Ti rods of 6 mm diameter were ECAPed at room temperature. During ECAP of tubular specimens, hydroxyapatite was filled in the tube. Grains and sub-grains of size approximately 1 μm were observed using transmission electron microscopy in both solid and tubular samples. Vickers microhardness measurements and surface energy calculations showed good improvement for ECAPed samples. This can be attributed to the fine grain structure achieved after processing. However, tubular sample showed marginally higher hardness and wettability. In vitro bioactivity studies carried out using 1.5× SBF indicate enhanced bioactivity in ECAPed samples. Also, cell response using rat skeletal muscle (L6) cells was found to be promising for both solid and tubular ECAPed specimens.