Fabrication and characterization of PCL/gelatin/chitosan ternary nanofibrous composite scaffold for tissue engineering applications

In the present study, we have fabricated a ternary composite nanofibrous scaffold from PCL/gelatin/chitosan, by electrospinning technique, using a solvent system—chloroform/methanol for polycaprolactone (PCL) and acetic acid for gelatin and chitosan, for tissue engineering applications. Field emission scanning electron microscopy (FE-SEM) was used to investigate the fiber morphology of the scaffold and it was found that the fiber morphology was influenced by the concentrations of PCL, gelatin, and chitosan in polymer solution during electrospinning. X-ray diffraction, Fourier transform infrared, and thermogravimetric (TG) analysis results showed some interactions among the molecules of PCL, gelatin, and chitosan within the scaffold. In-vitro cell culture studies were done by seeding L929 mouse fibroblasts on fabricated composite scaffold, which confirmed the cell viability, high cell proliferation rate, and cell adhesion on composite scaffold as indicated by MTT assay, DNA quantification, and FE-SEM analysis of cell-scaffold construct. Thus, the ternary composite scaffold made from the combination of PCL (synthetic polymer), gelatin, and chitosan (natural polymer) may find potential application in tissue engineering.     

Rapid Reversible Osmoregulation of Cytoplasmic Biomolecular Condensates of Human Interferon-α-Induced Antiviral MxA GTPase

We previously discovered that exogenously expressed GFP-tagged cytoplasmic human myxovirus resistance protein (MxA), a major antiviral effector of Type I and III interferons (IFNs) against several RNA- and DNA-containing viruses, existed in the cytoplasm in phase-separated membraneless biomolecular condensates of varying sizes and shapes with osmotically regulated disassembly and reassembly. In this study we investigated whether cytoplasmic IFN-α-induced endogenous human MxA structures were also biomolecular condensates, displayed hypotonic osmoregulation and the mechanisms involved. Both IFN-α-induced endogenous MxA and exogenously expressed GFP-MxA formed cytoplasmic condensates in A549 lung and Huh7 hepatoma cells which rapidly disassembled within 1–2 min when cells were exposed to 1,6-hexanediol or to hypotonic buffer (~40–50 mOsm). Both reassembled into new structures within 1–2 min of shifting cells to isotonic culture medium (~330 mOsm). Strikingly, MxA condensates in cells continuously exposed to culture medium of moderate hypotonicity (in the range one-fourth, one-third or one-half isotonicity; range 90–175 mOsm) first rapidly disassembled within 1–3 min, and then, in most cells, spontaneously reassembled 7–15 min later into new structures. This spontaneous reassembly was inhibited by 2-deoxyglucose (thus, was ATP-dependent) and by dynasore (thus, required membrane internalization). Indeed, condensate reassembly was preceded by crowding of the cytosolic space by large vacuole-like dilations (VLDs) derived from internalized plasma membrane. Remarkably, the antiviral activity of GFP-MxA against vesicular stomatitis virus survived hypoosmolar disassembly and subsequent reassembly. The data highlight the exquisite osmosensitivity of MxA condensates, and the preservation of antiviral activity in the face of hypotonic stress.     

Sigmoidal Function Classes for Feedforward Artificial Neural Networks

The role of activation functions in feedforward artificial neural networks has not been investigated to the desired extent. The commonly used sigmoidal functions appear as discrete points in the sigmoidal functional space. This makes comparison difficult. Moreover, these functions can be interpreted as the (suitably scaled) integral of some probability density function (generally taken to be symmetric/bell shaped). Two parameterization methods are proposed that allow us to construct classes of sigmoidal functions based on any given sigmoidal function. The suitability of the members of the proposed class is investigated. It is demonstrated that all members of the proposed class(es) satisfy the requirements to act as an activation function in feedforward artificial neural networks.     

Membrane dehumidification process using defect-free hollow fiber membrane

Water vapor removal by the polymeric membrane to reduce the energy cost during the water–gas shift reaction in a catalytic membrane reactor was investigated. In this study, polyamideimide (PAI) defect-free hollow fiber membranes were produced by a dry/wet phase inversion method. The purpose of this study was to investigate the water vapor removal efficiency under high pressure and high temperature. The morphologies of the hollow fiber membranes were characterized by SEM. The water vapor and hydrogen mixed gas separation properties were used to verify the performance of a defect-free membrane. The water vapor removal efficiency increased from 54% to 90% (at 120 °C) as a function of the operating conditions because of the enhanced water vapor flux. However, the H₂ retention ratio was negatively related to the water removal efficiency.     

Developing critical extrusion parameters for nylon 6, nylon 66, and nylon 46 polyamide from the rheology data

This paper describes a new approach to the rheological characterization of engineering plastics such as nylon 6, 66, and 46 polyamides using a capillary rheometer. The melt viscosity data as a function of temperature, shear rate, and residence time were measured and evaluated to demonstrate how to accurately predict critical extrusion parameters, such as barrel temperature profile, stock temperature window, and the screw design requirements, for extruding strip, tubing, and profiles. The results of this work provide a practical and simple quality control tool to select a polyamide resin for optimum processing, and to develop critical processing parameters for extrusion.     

Artificial neural networks in CT–PT contact detection in a PHWR

In a pressurized heavy water reactor (PHWR), contact between calandria tubes (CT) and pressure tubes (PT) makes them susceptible to delayed hydrogen cracking. Periodic inspection of the channels must be carried out to detect the contact. As the number of channels in a PHWR is very large (306 in a 230 MW plant) periodic in-service inspection of all the channels leads to an unacceptable downtime. A non-intrusive technique that employs a system identification method is presently used for contact detection. The technique tends to overpredict the number of channels in contact, i.e. they diagnose many channels as contacting while the channels are in fact not in contact. This puts a large number of healthy channels on the at risk list reducing the efficacy of the method. This paper demonstrates the power of artificial neural networks (ANNs) in diagnosing the CT–PT contact. A counterpropagation neural network consisting of a Kohonen layer and a Grossberg layer has been employed. The noise tolerance of the network has been demonstrated.     

A note on weight-based load balancing on SONET rings

In a recent paper, Cosares and Saniee [2] introduced the problem of balancing loads on SONET [1] rings. This note gives a counterexample to one of their results and then states the correct result.     

Uniform threshold intensity distribution-based quantitative multivariate imaging cytometry

Implementation of quantitative analytical approaches to image-based cellular assays remains a major challenge. We disclose a tool to achieve automatic rapid quantitative cellular imaging analysis based on uniform threshold intensity distribution. An acousto-optic tunable filter-based, quantitative multivariate imaging cytometer was set up to elucidate drug-induced cell death dynamics via cell viability and apoptosis/necrosis measurements in the human myeloid leukemia cell line, HL-60. Cells were treated with various drugs (camptothecin, naringenin, sodium salicylate) at different concentrations and time intervals. The developed protocol can directly depict and quantitate targeted cellular moieties, subsequently enabling a method that is applicable to various cellular assays with special reference to next generation drug discovery screening. This may also complement certain flow-cytometric measurements in studying quantitative physiology of cellular systems.     

Carbonized nano/microparticles for enhanced mechanical properties and electromagnetic interference shielding of cementitious materials

In the present work, carbon nano/microparticles obtained by controlled pyrolysis of peanut (PS) and hazelnut (HS) shells are presented. These materials were characterized by Raman spectroscopy and field emissionscanning electron microscopy (FE-SEM). When added to cement paste, up to 1 wt%, these materials led to an increase of the cement matrix flexural strength and of toughness. Moreover, with respect to plain cement, the total increase in electromagnetic radiation shielding effect when adding 0.5 wt% of PS or HS in cement composites is much higher in comparison to the ones reported in the literature for CNTs used in the same content.     

Optimization of microwave-assisted extraction for picroside I and picroside II from Picrorrhiza kurroa using Box-Behnken experimental design

The response surface methodology was employed to study the optimization of microwave-assisted extraction of picroside I and picroside II from Picrorrhiza kurroa Royle rhizomes. The effects of solid to solvent ratio, and extraction temperature, time and solvent on the yields of picroside I and picroside II have been investigated using Box-Behnken experimental design. The experimental data were fitted to second-order polynomial equations using multiple regression analysis and analyzed using the appropriate statistical method. By solving the regression equation and analyzing 3-D plots, the optimum extraction conditions were found to be: solid to solvent ratio, 10 : 90 (w/v); temperature, 60 °C; and extraction time, 60 s. Under the optimal conditions, the yields of picroside I and picroside II are 41.23 and 6.12 mg·g^–1 feed respectively, which are in good agreement with the predicted values. The ratio of solid to solvent significantly affects the yields of picroside I and picroside II. Application of microwave-assisted extraction of picroside I and picroside II from P. kurroa would dramatically reduce extraction time and solvent consumption.