Геннадий Петрович Котельников : к 65-летию со дня рождения

Few studies from low- and middle-income countries use qualitative methodologyto explore suicidal behavior among young people. In Cambodia, young peopleface the challenge of rapidly changing times and are vulnerable for suicidalbehavior as revealed by research in transitional economies. This study seeks togain a deeper understanding of the suicidal phenomena from a gender, psychosocialand cultural perspective. Six focus-group discussions were conductedamong boys and girls, aged 15–19 years, in two secondary schools in a suburbanarea close to Phnom Penh, the capital city. The data was analyzed using thematicanalysis approach. The participants highlighted the gender difference in suicidalbehavior by describing the suicide-prone, acting-out male as ‘plue plun’, whilesuicide-prone females were described as caught in constricted, tunneled-thinkingbehavior, expressed as ‘kath klei’. Parental attitude and family environment werealso pointed out as the chief causes of discontent and there was a strong wish onthe part of young people to find space for modern values within the traditionalfamily. The young people’s awareness of their challenges in everyday life suggeststhat school-based programs to prevent suicidal behavior ought to be gendersensitiveand peer-focused

Improved synthesis of 2,3-diacetamidouronates which are present in bacterial envelope

Diacetamidodideoxyuronic acids are components of lipopolysaccarides present in bacterial cell wall. There are very few publications reporting the preparation of this class of sugars. Hence, we present the synthesis of gluco-, galacto- and manno- configured sugars of 2,3-diacetamido-2,3-dideoxy-D-uronates. These monosaccharaides can be employed as glycosyl donors and acceptors in glycosylation reactions to produce larger glycosylates which can serve as components of antibiotics. Currently, the target molecules were synthesized in high yields with good reproducibility and scalability

Formation of zinc–zinc phosphate composite coatings by cathodic electrochemical treatment

The formation of zinc–zinc phosphate composite coatings by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed in this paper. The cathodic phosphating process offers some unique advantages—it requires no specific addition of accelerator in the bath, it is capable of producing good quality coatings even at low temperature, it permits deposition of coatings of desired thickness, thus offering benefits in terms of energy savings, decrease in processing cost and improvement in plant life. Being a cathodic process, there is no iron dissolution and no ferric phosphate sludge formation, which renders it an eco-friendly process. Based on the amount of coating mass as a function of process variables and the potential-time measurement, a pictorial model is proposed for the deposition of zinc phosphate coating. The surface morphology of the coatings exhibits plate-like crystals. The corrosion behaviour of cathodically phosphated mild steel substrate in 3.5% sodium chloride solution exhibits the stability of these coatings, which last for a week with no red rust formation. This is due to the presence of a composite layer of zinc and zinc phosphate that acts as a mechanical barrier against further corrosion for a considerably longer time. Being a cathodic process, the possibility of hydrogenation of steel is the major limitation of this methodology

Formation and characteristics of zinc phosphate coatings obtained by electrochemical treatment: Cathodic vs. anodic

Electrochemical treatment and galvanic coupling are some of the possible modes of acceleration of low temperature phosphating process. The cathodic and anodic treatments during phosphating influence the deposition mechanism, characteristic properties and the corrosion resistance of the resultant coatings in a differentway. The present paper aims to compare these aspects and to identify the possible applications of phosphate coatings obtained by these treatments

Contemporary approaches towards augmentation of distinctive heterogeneous catalyst for sustainable biodiesel production

In recent times, demand for energy has significantly increased due to the depletion of fossil fuels and the fast-industrial revolution. This has created a wide space for the development of sustainable and renewable energy sources. Biodiesel has attained exceptional contemplation among other biofuels due to the use of renewable and low-cost resources. Selection of suitable catalyst plays a vital role in biodiesel production by a catalytic transesterification reaction. Compared to homogeneous catalysts, heterogeneous catalysts are most preferred as they have high selectivity and stability with increased biodiesel yield. Heterogeneous catalyst has made incredible development in biodiesel production under mild operating conditions and has less impact on the environment. Nanocatalysts are the effective heterogeneous catalyst, which has brought a tremendous revolution in biodiesel production in recent years. Thus, present review provides a comprehensive analysis of the use of heterogeneous catalyst, importance and challenges associated in biodiesel production

Encapsulation of lipase in mesoporous silica yolk-shell spheres with enhanced enzyme stability

Enzyme encapsulation is an attractive method among the different immobilization strategies to improve the reusability and stability of enzymes because it can separate enzymes from a hazardous external environment. However, current encapsulation methods have limitations including enzyme leakage. In this study, a new approach based on a two-step soft templating method has been proposed to encapsulate lipase within substrate permeable mesoporous silica yolk-shell spheres. In the first step, lipase was immobilized onto epoxy functionalized silica nanospheres that serve as the core materials. The core materials were mixed with a fluorocarbon surfactant, FC4, to form a core-vesicle complex. In the second step, a mesoporous silica shell was assembled surrounding the core-vesicle complex to form the yolk-shell structure with the lipase encapsulated. The mesoporous silica shell has a pore size of 2.1 nm, which is permeable to the reactant and product while isolating the enzymes from harmful external conditions. The encapsulated lipase retained 87.5% of its activity after thermal treatment at 70 °C for 2 hours while the free enzyme lost 99.5% of its activity under the same treatment. Importantly, the encapsulated lipase shows significantly enhanced resistance to degradation by proteases

In vitro phosphorylation as tool for modification of silk and keratin fibrous materials

An overview is given of the recent work on in vitro enzymatic phosphorylation of silk fibroin and human hair keratin. Opposing to many chemical "conventional" approaches, enzymatic phosphorylation is in fact a mild reaction and the treatment falls within "green chemistry" approach. Silk and keratin are not phosphorylated in vivo, but in vitro. This enzyme-driven modification is a major technological breakthrough. Harsh chemical chemicals are avoided, and mild conditions make enzymatic phosphorylation a real "green chemistry" approach. The current communication presents a novel approach stating that enzyme phosphorylation may be used as a tool to modify the surface charge of biocompatible materials such as keratin and silk