Tailoring Wet Explosion Process Parameters for the Pretreatment of Cocksfoot Grass for High Sugar Yields

The pretreatment of lignocellulosic biomass is crucial for efficient subsequent enzymatic hydrolysis and ethanol fermentation. In this study, wet explosion (WEx) pretreatment was applied to cocksfoot grass and pretreatment conditions were tailored for maximizing the sugar yields using response surface methodology. The WEx process parameters studied were temperature (160–210 °C), retention time (5–20 min), and dilute sulfuric acid concentration (0.2–0.5 %). The pretreatment parameter set E, applying 210 °C for 5 min and 0.5 % dilute sulfuric acid, was found most suitable for achieving a high glucose release with low formation of by-products. Under these conditions, the cellulose and hemicellulose sugar recovery was 94 % and 70 %, respectively. The efficiency of the enzymatic hydrolysis of cellulose under these conditions was 91 %. On the other hand, the release of pentose sugars was higher when applying less severe pretreatment conditions C (160 °C, 5 min, 0.2 % dilute sulfuric acid). Therefore, the choice of the most suitable pretreatment conditions is depending on the main target product, i.e., hexose or pentose sugars.     

Oil phase evaporation-induced self-assembly of hydrophobic nanoparticles into spherical clusters with controlled surface chemistry in an oil-in-water dispersion and comparison of behaviors of individual and clustered iron oxide nanoparticles

We report a general method for preparing nanoparticle clusters (NPCs) in an oil-in-water emulsion system mediated by cetyl trimethylammonium bromide (CTAB), where previously only individual nanoparticles were obtained. NPCs of magnetic, metallic, and semiconductor nanoparticles have been prepared to demonstrate the generality of the method. The NPCs were spherical and composed of densely packed individual nanoparticles. The number density of nanoparticles in the oil phase was found to be critical for the formation, morphology, and yield of NPCs. The method developed here is scalable and can produce NPCs in nearly 100% yield at a concentration of 5 mg/mL in water, which is approximately 5 times higher than the highest value reported in the literature. The surface chemistry of NPCs can also be controlled by replacing CTAB with polymers containing different functional groups via a similar procedure. The reproducible production of NPCs with well-defined shapes has allowed us to compare the properties of individual and clustered iron oxide nanoparticles, including magnetization, magnetic moments, and contrast enhancement in magnetic resonance imaging (MRI). We found that, due to their collective properties, NPCs are more responsive to an external magnetic field and can potentially serve as better contrast enhancement agents than individually dispersed magnetic NPs in MRI.     

Singularly perturbed higher order periodic boundary value problems

The existence of positive periodic solutions is proved for the higher order singular differential equation

(0.1)     

The effect of plasticization on craze microstructure

The structure of crazes in plasticized polystyrene has been studied by means of small-angle x-ray scattering and optical interference microscopy. Addition of plasticizer causes a rapid increase in the mean fibril diameter D and a slow decrease in the craze fibril volume fraction v_f. The crazing stress σ_c was also measured and it was found that the product D σ_c is independent of plasticizer concentration. These results are shown to be consistent with the entanglement model for controlling v_f and the meniscus instability model of craze thickness growth.     

Nickel(II) and copper(II) complexes of 2,2’‐bibenzo[d]thiazole: Synthesis,characterisation and biological studies

Benzothiazole moiety has gained a lot of attention because of its importance as essential pharmacophore in the development of metal based drugs. Nickel(II) and copper(II) complexes of a benzothiazole based ligand, 2,2’‐bibenzo[d]thiazole (L¹), synthesized by the reaction of benzothiazole‐2‐carbonylchloride and o‐aminothiophenol, is reported. The compounds were characterised by elemental and percentage metal analyses, spectroscopic (FTIR and UV–vis), ¹H and ¹³C NMR, Mass spectra, thermal, magnetic moment and molar conductance analyses. The mass spectra, elemental and percentage metal composition of the metal complexes gave a 2:1 ligand to metal stoichiometric mole ratio. The spectral data showed that the ligand was coordinated to the metal ions through the nitrogen atoms of the benzothiazole moiety. The electronic spectra and magnetic susceptibility measurements showed that the nickel and copper complexes adopted square planar geometries. The ligand and its metal(II) complexes were screened against some drug resistant microbes and were found to exhibit varied degree of antimicrobial activities. The nickel complex was more active compared to ciprofloxacin against Staphylococcus aureus and Bacillus cereus. Similarly, the antioxidant potential of the ligand was evaluated. The ligand is a better ferrous ion chelating agent compared to 1,10‐phenanthroline and 2,2‐bipyridine. The ligand and its complexes exhibited good antimicrobial and Fe²⁺ chelating properties making them probable compounds of interest in antibiotic and antioxidant drug researches.     

Analysis of stratified thermal storage systems: An overview

The presence of stratification is well known to improve the performance of stratified thermal energy storage systems (STESS). The major energy and exergy methods for modeling and assessing the performance of STESS are reviewed in this presentation. Current analytical and numerical methods for modeling STESS are surveyed, with their strengths and weaknesses. An extensive survey of performance assessment methods based on energy, entropy and exergy analyses is also presented. This survey highlights entropy generation ratios, which are based on second law considerations, as effective in quantifying the improvements in STESS performances that result from the presence of stratification unlike energy-based measures. The entropy generation number, N _s is suggested as an effective tool for future performance studies on STESS.     

Antennas on quasi synthetic media

This paper examines the differences and/or similarities between some of the commonly used canonical equations describing the effective permittivity and permeability of heterogeneous substrates with dielectric or metallic inclusions, at microwave frequencies. Graphical results are presented for the different structures considered. Simulated results from heterogeneous mixtures with both dielectric and metallic inclusions are presented, and compared with results from the canonical equation representation. Simulated results of a patch antenna on a heterogeneous medium and on its homogeneous equivalent have also been presented.