Effect of assembly pH and ionic strength of chitosan/casein multilayers on benzydamine hydrochloride release

Abstract

Multilayer biopolyelectrolyte films are built from chitosan and casein by layer-by-layer deposition onto corona precharged poly(DL-lactic acid) substrate. Such structure allows optimization with respect to the morphology and ability of drug immobilization and release by changing the assembly conditions. Variation of chitosan and casein solutions ionic strength and chitosan solution pH at constant casein solution pH, effects significantly the polyelectrolyte multilayer structure and drug release. pH and ionic strength increase change the morphology from dense to loose, and the ionic strength increase let to screening effect and complexation of the drug, resulting in slow drug release.     

Distribution Coefficients of 60 Elements on Cation and Anion-Exchange Resin in Ammonium Chloride Solutions

ABSTRACT

Ammonium chloride is a widely available non-corrosive and non-toxic chemical. When in contact with protein NH₄Cl is non-destructive and allows softer conditions for labeling of organic substances. These properties make NH₄Cl appropriate for use in multiple areas such as pharmaceutical production, low-background research, etc. For such purposes, a multitude of pure elements could be applied. In order to obtain pure elements their separation (purification) is necessary. One of the most successful methods of elements separation is ion exchange. In this work, we study the distribution coefficient of 60 elements on anion exchange (Dowex 1-x8) and cation exchange (Dowex 50w-x8) resins with NH₄Cl solutions with varying concentrations via ICP-MS.     

Electron microscopy study of ion beam synthesized β-FeSi2

β-FeSi₂ embedded in a Si matrix was prepared by ion beam synthesis (IBS). Two step implantation, with energies 60 and 20 keV, of two different doses of the iron ions, 5 × 10¹⁵ and 5 × 10¹⁶ cm⁻¹, was performed. After the implantation, the samples were subjected to rapid thermal annealing (RTA) at 900 °C. The crystal structure of the resulting material was studied using cross-sectional transmission electron microscopy (XTEM), including high-resolution electron microscopy (HREM). The comparison of the XTEM images with the initial iron ions implantation profiles, simulated by SRIM (Stopping and Range of Ions in Matter) demonstrate that the process of IBS, followed by RTA, preserves the initial implantation profile, implying a negligible Fe atoms diffusion velocity in comparison with the one of the chemical reaction between Fe and Si. The XTEM images show that continuous β-FeSi₂ layers are fabricated when there is a stoichiometric region in the initial implantation profile. Fe concentration lower than the stoichiometric one in the whole implantation range results in formation of β-FeSi₂ nanocrystallites embedded in the Si matrix. The behavior of the absorption coefficient energy dependences, obtained from the optical transmittance and reflectance measurements, reflects the different crystal structures forming in the two types of samples.     

Effect of Al and Ce oxide layers electrodeposited on OC4004 stainless steel on its corrosion characteristics in acid media

The changes in the corrosion characteristics of stainless steel OC4004 in 0.1 M HNO₃ after electrodeposition of thin Al and Ce oxide films on it has been investigated. The Ce₂O₃–CeO₂ layers have been found to possess a pronounced stabilizing effect on the steel passive state and on its corrosion resistance, respectively, whereas the Al₂O₃ layers do not improve considerably the corrosion behaviour of the SS/Al₂O₃ system. A twice-lower corrosion current was observed with a ternary SS/Al₂O₃/Ce₂O₃–CeO₂ system in the passive region, while the zones of potentials, where the steel is in a stable passive state, are not changed. The obtained results permit the assumption that the cerium oxides layer acts as an effective cathode playing a determining role with respect to the improvement of the corrosion behavior of the steel. It has been concluded that when the SS/Al₂O₃/Ce₂O₃–CeO₂ system is used in media containing nitric acid, the corrosion will proceed at potentials where the passive state of steel would not be disturbed.     

Influence of cholesterol on the kinetics of lipid autoxidation and on the antioxidative properties of α‐tocopherol and quercetin

The autoxidation kinetics of triacylglycerols of sunflower oil (TGSO) in the presence of 10% cholesterol (Chol) at 80, 90 and 100 °C has been studied. The process was followed by monitoring the peroxide value and the formation of conjugated dienes. Cholesterol has been found to exhibit a prooxidative effect. During the oxidation of the mixture (TGSO/Chol), cholesterol peroxides were not registered. It is supposed that the initial amount of cholesterol peroxides formed decomposes to free radicals and that these radicals accelerate TGSO oxidation. A kinetic analysis of the antioxidative behavior of α‐tocopherol and quercetin (2.9 x 10^?4‐17.8 × 10^?4 M) in both TGSO and TGSO/Chol at 100 °C was performed. It was found that the effectiveness, strength, and activity of α‐tocopherol are greater in TGSO/Chol than in TGSO, while these parameters for quercetin are practically the same in both lipid systems. The differences in the mechanism of action of α‐tocopherol and quercetin are discussed.     

Inhibited Oxidation of Lipids II: Comparison of the Antioxidative Properties of Some Hydroxy Derivatives of Benzoic and Cinnamic Acids

The antioxidative properties of p-hydroxy-benzoic acid, vanillic acid, syringic acid, 3,4-dihydroxy-benzoic acid, p-coumaric acid, ferulic acid, sinapic acid and caffeic acid in lard autoxidation at 100°C are compared. The effect of phenolic acids is investigated within the concentration range 0.02 – 0.20 wt %. It is proved that the derivatives of the benzoic acid have weaker inhibiting properties than is the case of the corresponding analogues of the cinnamic acid due to the more active participation of the inhibitor in the elementary reactions of propagation and initiation of the radical chain process. The activity (a complex parameter demonstrating the efficiency and strength of the antioxidant) of the phenolic acids investigated decreases in the sequence: caffeic acid >3,4-dihydroxy-benzoic acid > sinapic acid > syringic acid>ferulic acid>p-coumaric acid>vanillic acid. The increase in concentration of the acids investigated is most advisable in the case of sinapic, syringic and ferulic acids which are not consumed in side reactions.     

Sea-level rise and its possible impacts given a 'beyond 4°C world' in the twenty-first century

The range of future climate-induced sea-level rise remains highly uncertain with continued concern that large increases in the twenty-first century cannot be ruled out. The biggest source of uncertainty is the response of the large ice sheets of Greenland and west Antarctica. Based on our analysis, a pragmatic estimate of sea-level rise by 2100, for a temperature rise of 4°C or more over the same time frame, is between 0.5 m and 2 m--the probability of rises at the high end is judged to be very low, but of unquantifiable probability. However, if realized, an indicative analysis shows that the impact potential is severe, with the real risk of the forced displacement of up to 187 million people over the century (up to 2.4% of global population). This is potentially avoidable by widespread upgrade of protection, albeit rather costly with up to 0.02 per cent of global domestic product needed, and much higher in certain nations. The likelihood of protection being successfully implemented varies between regions, and is lowest in small islands, Africa and parts of Asia, and hence these regions are the most likely to see coastal abandonment. To respond to these challenges, a multi-track approach is required, which would also be appropriate if a temperature rise of less than 4°C was expected. Firstly, we should monitor sea level to detect any significant accelerations in the rate of rise in a timely manner. Secondly, we need to improve our understanding of the climate-induced processes that could contribute to rapid sea-level rise, especially the role of the two major ice sheets, to produce better models that quantify the likely future rise more precisely. Finally, responses need to be carefully considered via a combination of climate mitigation to reduce the rise and adaptation for the residual rise in sea level. In particular, long-term strategic adaptation plans for the full range of possible sea-level rise (and other change) need to be widely developed.     

Thin film transformer and its analysis by integral equation method

We propose a thin film transformer for small electronic devices, and apply the integral equation method to analyze this transformer. Both the primary and secondary coils of the film transformer are arranged coaxially on the layer and multiply laminated. The operation principal of the transformer is based on the skin effect and the mutual effect between the coils at high frequency. Because of the coaxially arranged coils, the magnetic field of the transformer can be modeled with an axisymmetric assumption. Using the model, we evaluate the electromagnetic field and calculate the lumped circuit parameters, i.e., inductance and resistance, which are compared with experimental values     

Evolution and governance of the biotechnology and pharmaceutical industry of China

The high-speed growth of China’s biotechnology industry during the past 20 years presents an excellent opportunity to examine its overall evaluation and governance from the perspective of science and technology policies. Although China’s biotechnology industry has achieved tremendous extension both in scale and structure, the strengths it has gained from achievements in research and development activities have been significantly weakened in relation to processes of commercialization. After examining the definition of China’s biotechnology industry as well as its evolution, the authors of this paper employ Actor-Networks Theory as a basic theoretical framework to reveal how China’s biotechnology industry develops in the form of evolving networks within the country’s social context and to identify what kinds of relationships exist among the relevant factors. Our hope is to provide guiding insights for improving the governance of China’s biotechnology industry both in policy and in management practices.     

Implementation of a Forest Biomass-Based Biofuel Industry： A Canadian Experience

The forest biomass is an abundant renewable resource from which biofuels can be derived. In the Kraft process, the cellulose is extracted from the wood to form the paper pulp while the other organic components, primarily hemicelluloses and lignin, are burnt to produce steam. It is possible to divert part of the hemicelluloses or lignin to produce fuels on site, a mode of operation referred to as the integrated forest biorefinery. Hemicelluloses can be hydrolysed into sugars which in turn are converted into ethanol or butanol, while lignin can be extracted from a residual process stream, the black liquor, by acid precipitation, de-ionized, dried and directly used as a fuel or further processed into value added chemicals. Biorefinery processes have been proposed and analysed by simulation on Aspen Plus. Intensive integration of thermal energy, water and material systems is of paramount importance to the sustainability of the global site; the increased energy load on the utility systems could cause rising dependency of the global site on fossil fuels. To avoid this consequence, a new original energy efficiency analysis and enhancement methodology has been developed and validated on actual Canadian Kraft mills before being applied to the integrated biorefinery and, has produced remarkable results far superior to the current engineering practice. This has led to the concept of the GIFBR （green integrated forest biorefinery）, i.e., an industrial site with zero fossil fuel consumption and reduced GHG （greenhouse gases） emissions vs. the Kraft process and biorefinery plant alone. The GIFBR incorporates a woody biomass gasifier producing syngas as a fuel for the integrated biorefinery and for steam production or sale. It can also include a CHP （combined heat and power） unit driven by steam made available by liberated production capacity from the installed power plant.