Calculation of the molar volume of liquid hydrocarbons

Equations are proposed for calculating the molar volume of liquid hydrocarbons used in production of surfactants. With such data, it will be possible to calculate most of the physicochemical properties of these hydrocarbons to solve many process problems. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 39–41, Novemmber–December, 2006.     

Relations between anxiety sensitivity, distress tolerance, and fear reactivity to bodily sensations to coping and conformity marijuana use motives among young adult marijuana users.

The present investigation examines anxiety sensitivity, distress tolerance, and fear reactivity to bodily sensations in relation to Coping and Conformity marijuana use motives among a sample of young adult marijuana users (n = 135; 46.7% women; Mage = 20.45, SD = 5.0). After controlling for current marijuana use frequency (past 30 days), daily cigarette smoking rate, average volume of alcohol used over the past year, negative affectivity, and other marijuana use motives, anxiety sensitivity was significantly and uniquely associated with Coping and Conformity motives for marijuana use. Distress tolerance evidenced significant and unique incremental relations to Coping motives, whereas fear reactivity to bodily sensations was unrelated to any marijuana use motive. These results provide novel information related to the role of emotional sensitivity and tolerance factors as they pertain to specific types of motives for marijuana use among young adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Survey on some contaminants in white sugar from Serbian sugar beet refineries

Refined white sugar is a very pure food product, even though it contains very small amounts of soluble and insoluble impurities. The content of these impurities has nutritional significance and determines the usefulness of sugar for various industrial applications. The main quality criteria used to indicate the content of these impurities are ash and colour. The aim of this paper was to evaluate the quality according to the EU sugar market regime and the content of iron, copper and zinc in white sugar samples from Serbian sugar beet refineries during the 2003 campaign. A total of 166 samples representative of the production of four Serbian sugar refineries were investigated. After wet digestion the concentrations of iron, copper and zinc were determined by flame atomic absorption spectrometry. The mean content of iron, copper and zinc in sugar samples was 0.37 mg/kg, 0.06 mg/kg and 0.02 mg/kg and was significantly different from the average content 0.28 mg/kg, 0.09 mg/kg and 0.07 mg/kg respectively in the analysed European sugar factories. The data were also compared with literature values for commercial white sugar samples from European sugar beet refineries and European legislation set for copper and zinc. Furthermore, the quality of produced sugar was evaluated according to the standards of the European Union indicating that 76% of all investigated Serbian samples belonged to the second sugar quality category.     

Separation of non-sucrose compounds from sugar-beet syrup by ultrafiltration with ceramic membrane containing static mixer

The aim of this work was to investigate possible improvement of non-sucrose compounds separation from the syrup of raw brown sugar by application of a static mixer in an ultrafiltration process. The static mixer was expected to reduce the concentration polarization and fouling of the membrane. Non-affinated B sugar from the second stage of crystallization, diluted to 60°Bx dry matter, was used for preparing the solution subjected to the ultrafiltration. The cross-flow filtration, at a laboratory level, was carried out on the tubular ceramic membrane (Schumasiv Pall, USA), with a pore diameter of 5 nm. The separation was performed under various working conditions, with and without the presence of static mixer. The effect of turbulence promotion on filtration performances was investigated by using Kenics static mixer (FMX8124-AC, Omega). The process efficiency was quantified through the achieved values of the permeate flux, its colour and dry matter content, while the working factors were: fluid flow-rate, temperature, transmembrane pressure (TMP) and process duration. The positive effects of mixer application were proved.     

Optimization of pH value and aluminium sulphate quantity in the chemical treatment of molasses

The aim of this investigation was to find the optimal working conditions for the chemical treatment of molasses that guarantee coagulation and precipitation of undesired macromolecules. Twenty experiments were performed, within the limits: 3.5pH8.5 and 0.1 mol Al/lc0.5 mol Al/l, on samples of molasses treated with Al₂(SO₄)₃ as a precipitant. The efficiency of the treatment was controlled through measuring both the zeta potential and solution absorbance at 560 nm. By analysing the experimental results, it was concluded that the optimum lies within reduced limits of: 4pH7 and 0.2 mol Al/lc0.4 mol Al/l, which covers nine experimental points. Based on these measurements, a mathematical model of absorbance changes was defined, in terms of pH and Al₂(SO₄)₃ quantity. The model was taken as the objective function, and the optimal calculated values were obtained: pH=5.3 and c=0.34 mol Al/l. They guarantee a minimal absorbance value of: 0.124 at 560 nm.     

Reduction of solid content in starch industry wastewater by microfiltration

Wastewater obtained in the production process of wheat starch and vital wheat gluten was treated by microfiltration through a ceramic tubular membrane with 200 nm pore sizes. The consumption of process water would thus be reduced, the starch would be recovered to a greater extent and the wastewater problem would consequently be solved. Reduction of the occurrence of polarization layer on the membrane and the constant wastewater permeate flux through the membrane was maintained by inserting of the mixer Kenics inside the membrane tube. The maximum value of the permeate flux (24 L m⁻² h⁻¹) without the use of a static mixer was achieved at 3 × 10⁻⁵ Pa and at a flow rate of 150 L/h, for wastewater samples initially allowed to settle for 4 h prior microfiltration. Under the very same conditions of the working parameters, the use of a static mixer enables a flux that is up to two or three times more intensive compared to the values obtained without using a mixer. Microfiltration reduces the wastewater dry matter from 11 000 to 4000 mg/L, lessens the chemical oxygen demand by 74%, i.e. from 21 000 to 5100 mgO₂/L and significantly decreases the values of the suspended matter, namely from 9000 to 300 mg/L.     

Identification of Phenylpyrazolone Dimers as a New Class of Anti-Trypanosoma cruzi Agents

Chagas disease is becoming a worldwide problem; it is currently estimated that over six million people are infected. The two drugs in current use, benznidazole and nifurtimox, require long treatment regimens, show limited efficacy in the chronic phase of infection, and are known to cause adverse effects. Phenotypic screening of an in-house library led to the identification of 2,2′-methylenebis(5-(4-bromophenyl)-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one), a phenyldihydropyrazolone dimer, which shows an in vitro pIC₅₀ value of 5.4 against Trypanosoma cruzi. Initial optimization was done by varying substituents of the phenyl ring, after which attempts were made to replace the phenyl ring. Finally, the linker between the dimer units was varied, ultimately leading to 2,2′-methylenebis(5-(3-bromo-4-methoxyphenyl)-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one (NPD-0228) as the most potent analogue. NPD-0228 has an in vitro pIC₅₀ value of 6.4 against intracellular amastigotes of T. cruzi and no apparent toxicity against the human MRC-5 cell line and murine cardiac cells.