Fabrication and mechanical characterization of biodegradable and synthetic polymeric films: Effect of gamma radiation

Chitosan (1 wt%, in 2% aqueous acetic acid solution) and starch (1 wt%, in deionised water) were dissolved and mixed in different proportions (20–80 wt% chitosan) then films were prepared by casting. Tensile strength and elongation at break of the 50% chitosan containing starch-based films were found to be 47 MPa and 16%, respectively. It was revealed that with the increase of chitosan in starch, the values of TS improved significantly. Monomer, 2-butane diol-diacrylate (BDDA) was added into the film forming solutions (50% starch-based), then casted films. The BDDA containing films were irradiated under gamma radiation (5–25 kGy) and it was found that strength of the films improved significantly. On the other hand, synthetic petroleum-based polymeric films (polycaprolactone, polyethylene and polypropylene) were prepared by compression moulding. Mechanical and barrier properties of the films were evaluated. The gamma irradiated (25 kGy) films showed higher strength and better barrier properties.     

Effectiveness of silane monomer and gamma radiation on chitosan films and PCL-based composites

Chitosan films were prepared by casting from its 1% (w/w) solution. Tensile strength (TS) and tensile modulus (TM) of chitosan films were found to be 30 MPa and 450 MPa, respectively. Silane monomer (3-aminopropyl tri-methoxysilane) (0.25%, w/w) was added into the chitosan solution (1%, w/w) and films were casted. Then films were exposed to gamma radiation (5–25 kGy) and mechanical properties were investigated. It was found that at 10 kGy, the values of TS and TM were improved significantly. Silane grafted chitosan film reinforced poly(caprolactone) (PCL)-based tri-layer composites were prepared by compression molding. Silane improved interfacial adhesion between chitosan and PCL in composites. Surface of the films was investigated by scanning electron microscope (SEM) and found better morphology for silane grafted films.     

Effect of some biopolymers on the rheological behavior of surimi gel

The objective of this study was to investigate the effect of selected biopolymers on the rheological properties of surimi. In our paper, we highlight the functional properties and rheological aspects of some starch mixtures used in surimi. However, the influence of some other ingredients, such as cryoprotectants, mannans, and hydroxylpropylmethylcellulose (HPMC), on the rheological properties of surimi is also described. The outcome reveals that storage modulus increased with the addition of higher levels of starch. Moreover, the increasing starch level increased the breaking force, deformation, and gel strength of surimi as a result of the absorption of water by starch granules in the mixture to make the surimi more rigid. On the other hand, the addition of cryoprotectants, mannans, and HPMC improved the rheological properties of surimi. The data obtained in this paper could be beneficial particularly to the scientists who deal with food processing field.     

Fermi energy level tuning for high performance dye sensitized solar cells using sp2 selective nitrogen-doped carbon nanotube channels

Here, we find that doping sp(2) selective nitrogen, N sp(2), into carbon nanotube (CNT) channels induces a positive shift in the Fermi level of TiO(2) photoelectrodes. It is found that this results in the large diffusion coefficient of solar driven electrons for increasing the photocurrent as well as in the low recombination rate for improving open circuit voltage with 0.74 V, which could not be overcome by using pristine CNT channels with 0.66 V.     

Effect of monomer-treated inorganic fillers on mechanical,rheological, and thermal properties of LLDPE nanocomposites

This article discusses the role of nanoscale calcium carbonate (nCC) surface treatment in affecting the mechanical, rheological, and thermal properties of linear low-density polyethylene (LLDPE). The mechanical tests indicated that nCC could simultaneously reinforce and toughen LLDPE. In addition, the composite sample with methacrylic acid (MA)-treated nanoparticles shows further increased mechanical properties as compared to unmodified nanoparticles. In the presence of dicumyl peroxide (DCP), a small amount of MA could increase markedly the mechanical properties of LLDPE/nCC composites. The results of rheological property analysis indicated that the viscosity increased with increasing amount of the filler, especially at low shear rates, but showed a substantial reduction with increasing concentration of the reactive monomer. The thermal behavior of these materials is evaluated by differential scanning calorimetry and thermogravimetric analysis. The addition of a small amount of MA and DCP enhances the stabilization of the blends.     

Self-adaptive differential evolution incorporating a heuristic mixing of operators

A considerable number of differential evolution variants have been proposed in the last few decades. However, no variant was able to consistently perform over a wide range of test problems. In this paper, propose two novel differential evolution based algorithms are proposed for solving constrained optimization problems. Both algorithms utilize the strengths of multiple mutation and crossover operators. The appropriate mix of the mutation and crossover operators, for any given problem, is determined through an adaptive learning process. In addition, to further accelerate the convergence of the algorithm, a local search technique is applied to a few selected individuals in each generation. The resulting algorithms are named as Self-Adaptive Differential Evolution Incorporating a Heuristic Mixing of Operators. The algorithms have been tested by solving 60 constrained optimization test instances. The results showed that the proposed algorithms have a competitive, if not better, performance in comparison to the-state-of-the-art algorithms.     

On-line optimization design of sliding mode guidance law with multiple constraints

The design of terminal guidance law with impact angle constraint is required for air-to-ground guided weapons to increase their warhead effect. The variable structure guidance law that consists of diving plane guidance and turning plane guidance equations with impact angle constraint is derived, and the saturation function is introduced into the design of reaching law control to weaken the chattering of the guidance system. The influence of four guidance parameters (i.e., reaching law factor, switching item gain, angle error item factor, and boundary layer thickness) on guidance performance is studied and three typical constraints (i.e., heating rate, normal load factor, and dynamic pressure) are analyzed. An optimization model is established for this problem and the feasibility of on-line optimization on guidance law parameters by the Sequential Quadratic Programming (SQP) algorithm is discussed as well. Simulation results show that the on-line optimization of the derived guidance law not only satisfies specified constraints, but also minimizes the fuel cost during the flying course. Moreover, the optimization process can be completed in a few seconds so that it is suitable for on-board applications.     

Effect of gamma radiation on the performance of jute fabrics-reinforced polypropylene composites

Jute fabrics-reinforced polypropylene (PP) composites (50% fiber) were prepared by compression molding. Composites were fabricated with non-irradiated jute fabrics/non-irradiated PP (C-0), non-irradiated jute fabrics/irradiated PP (C-1), irradiated jute fabrics/non-irradiated PP (C-2) and irradiated jute fabrics/irradiated PP (C-3). It was found that C-3 composite performed the best mechanical properties over other composites. Total radiation dose varied from 250–1000 krad and composites made of using 500 krad showed the best results. The optimized values (C-3 composites) for tensile strength (TS), bending strength (BS) and impact strength (IS) were found to be 63 MPa, 73 MPa and 2.93 kJ/m², respectively.     

A Probe of Valence and Conduction Band Electronic Structure of Lead Oxide Films for Photodetectors

We investigate how the electronic structure of amorphous lead oxide (a-PbO) films deposited on ITO substrate is changed after annealing at various temperatures. Both experimental soft X-ray spectroscopic and density functional theory (DFT) based computational techniques are used to explore the electronic structure of this material. X-ray emission, resonant X-ray inelastic scattering, and X-ray absorption spectroscopic techniques are employed to directly probe the valence and conduction bands. We discover that the films are very stable and remain amorphous when exposed to temperatures below 300 °C. An amorphous-to-polycrystalline (α-PbO phase) transformation occurs during annealing at 400 °C. At 500 °C, an alpha to beta phase change is observed. These structural modifications are accompanied by the band gap value changing from 1.4±0.2 eV to 2.0±0.2 eV upon annealing at 400 °C and to 2.6±0.2 eV upon annealing at 500 °C. A difference between surface and bulk structural properties is found for all samples annealed at 500 °C and above; these samples also exhibit an unexpected suppression of O : 2p density of states (DOS) near the bottom of the conduction band, whereas additional electronic states appear well within the valence band. This study provides a significant step forward to understanding the electronic properties of two polymorphic forms of PbO needed for optimization of this material for use in X-ray sensors.