Highly oxygenated organic molecules produced by the oxidation of benzene and toluene in a wide range of OH exposure and NO_<i>x</i> conditions

Oxidation of aromatic volatile organic compounds (VOCs) leads to the formation of tropospheric ozone and secondary organic aerosol, for which gaseous oxygenated products are important intermediates. We show, herein, the experimental results of highly oxygenated organic molecules (HOMs) produced by the oxidation of benzene and toluene in a wide range of OH exposure and NOx conditions. The results suggest that multigeneration OH oxidation plays an important role in the product distribution, which likely proceeds more preferably via H subtraction than OH addition for early generation products from light aromatics. More oxygenated products present in our study than in previous flow tube studies, highlighting the impact of experimental conditions on product distributions. The formation of dimeric products, however, was suppressed and might be unfavorable under conditions of high OH exposure and low NOx in toluene oxidation. Under high-NOx conditions, nitrogen-containing multifunctional products are formed, while the formation of other HOMs is suppressed. Products containing two nitrogen atoms become more important as the NOx level increases, and the concentrations of these compounds depend significantly on NO2. The highly oxygenated nitrogen-containing products might be peroxyacyl nitrates, implying a prolonged effective lifetime of RO2 that facilitates regional pollution. Our results call for further investigation on the roles of high-NO2 conditions in the oxidation of aromatic VOCs.

Thermal and Quasi-Static Mechanical Characterization of Polyamide 6-Graphene Nanoplatelets Composites

The growing demand for lightweight and multifunctional products in numerous industrial fields has recently fuelled a growing interest in the development of materials based on polymer matrices including graphene-like particles, intrinsically characterized by outstanding mechanical, thermal, and electrical properties. Specifically, with regard to one of the main mass sectors, which is the automotive, there has been a significant increase in the use of reinforced polyamides for underhood applications and fuel systems thanks to their thermal and chemical resistance. In this frame, polyamide 6 (PA6) composites filled with graphene nanoplatelets (GNPs) were obtained by melt-compounding and compared in terms of thermal and mechanical properties with the neat matrix processed under the same condition. The results of the experimental tests have shown that the formulations studied so far offer slight improvements in terms of thermal stability but much more appreciable benefits regarding both tensile and flexural parameters with respect to the reference material. Among these effects, the influence of the filler content on the strength parameter is noteworthy. However, the predictable worsening of the graphene sheet dispersion for GNPs contents greater than 3%, as witnessed by scanning electron images of the tensile fractured sections of specimens, affected the ultimate performance of the more concentrated formulation.

Highly Oxygenated Organic Molecules Produced by the Oxidation of Benzene and Toluene in a Wide Range of OH Exposure and NO_x Conditions

Oxidation of aromatic volatile organic compounds (VOCs) leads to the formation of tropospheric ozone and secondary organic aerosol, for which gaseous oxygenated products are important intermediates. We show herein experimental results of highly oxygenated organic molecules (HOMs) produced by the oxidation of benzene and toluene in a wide range of OH exposure and NOx conditions. The results suggest multi-generation OH oxidation plays an important role in the product distribution, which likely proceeds more preferably via H subtraction than OH addition for early-generation products from light aromatics. Our experimental conditions promote the formation of more oxygenated products than previous flow-tube studies. The formation of dimeric products however was suppressed and might be unfavorable under conditions of high OH exposure and low NOx in toluene oxidation. Under high-NOx conditions, nitrogen-containing multifunctional products are formed, while the formation of other HOMs is suppressed. Products containing two nitrogen atoms become more important as the NOx level increases, and the concentrations of these compounds depend significantly on NO2. The highly oxygenated nitrogen-containing products might be peroxyacylnitrates, implying a prolonged effective lifetime of RO2 that facilitates regional pollution. Our results call for further investigation on the roles of high-NO2 conditions in the oxidation of aromatic VOCs.

Optimization of biotechnology for the production of fermented milk drink based on milk obtained from holstein cows

The article presents research on the development of a new technology for the production of fermented milk drink based on milk (Holstein breed of cows) using a vegetable additive obtained by extrusion processing of sprouted chickpea grain. The production of fermented milk drinks with the use of such plant additives allows us to develop new multifunctional products due to the content of bioavailable nutrients, vitamins, etc. in the extruded sprouted chickpea grain. The developed production technology and fermented milk drink meet all existing requirements.

INFLUENCE OF CULTIVATION CONDITIONS ON ANTIMICROBIAL AND ANTI-ADHESIVE ACTIVITY OF SURFACTANTS OF BACTERIA OF ACINETOBACTER, RHODOCOCCUS AND NOCARDIA GENERA

Microbial surfactants are multifunctional products because they cannot only reduce the surface tension at the interface and emulsify various substrates, but also display antimicrobial and anti-adhesion activity (including the ability to destroy biofilms). However, under various conditions of producer’s cultivation the surfactant composition and their properties can vary. One of the approaches to increasing antimicrobial and anti-adhesion activity of the surfactant can be an increase in medium of producer cultivation content of activators of key enzymes biosynthesis of aminolipids − the most effective antimicrobial agents. Activators of NADP+-dependent glutamate dehydrogenase in Acinetobacter calcoaceticus IMV B-7241 are cations of calcium, magnesium and zinc, Rhodococcus erythropolis IMV Ac-5017 and Nocardia vaccinii IMV B-7405 – calcium.Surfactants were extracted from supernatant of cultural liquid by mixture of chloroform and methanol (2:1). Antimicrobial activity of surfactants was determined by index of minimum inhibitory concentration (MIC), antiadhesive − by spectrophotometry. The degree of biofilm destruction was determined as difference between the number of adhered cells in untreated and treated with surfactant holes of polystyrene immunological plate containing pre-formed biofilm of test cultures and was expressed as a percentage. It was found that addition of CaCl2 (0.1 g/l) into medium cultivation of R. erythropolis IMV Ac-5017, increasing concentration of this salt to 0.4 g/l in medium for N. vaccinii IMV B-7405 growth, introduction of CaCl2(0.1 g l) and increasing MgSO4·7H2O content to 0.2 g/l, or adding Zn2+(38 μM) into medium cultivation of A. calcoaceticus IMV B-7241 was accompanied by synthesis of surfactants MICs of which against test cultures were 1.2–13 times lower, their adhesion on abiotic surfaces treated with such surfactants was on average 10−40 % lower, and the degree of biofilms destruction was 7−20 % higher than indicators established for surfactants obtained on the base medium. The obtained data indicate the possibility of regulating antimicrobial and anti-adhesion activity of microbial surfactants under producer cultivation.