Volume 11, No. 3 (2010)
Articles
THERMAL DEGRADATION IN NON-ISOTHERMAL CONDITIONS OF SOME FERROCENE DERIVATIVES
Gabriela Lisa(1)*, Daniela Apreutesei Wilson(1, 2), Dan Scutaru(1), Felicia Olaru(1), Valentina Botnaru(1), Catalin Lisa(1)
The study of the thermal behavior of some symmetrically monosubstituted and disubstituted ferrocene derivatives, with liquid crystal properties, presented in this work, assesses the structure – thermal stability relation, necessary for the knowledge of the field of applicability, of the processing conditions and for the valorization of industrial waste. The influence of the length of the flexible part, of the azoaromatic unit and of the presence of the cholesteryl unit on thermal stability has been proven.
AN ANALYTICAL METHOD FOR CHEMICAL SPECIATION OF SELENIUM IN SOIL
Mihaela M. Aldea(1)*, Constantin Luca(2)
Selenium is an essential microelement, sometimes redoubtable, through its beneficial role - risk depending on its concentration in the food chain, at low dose is an important nutrient in the life of humans and animals, contrary at high doses, it becomes toxic. Selenium may be find itself in the environment (soil, sediment, water) in many forms (oxidized, reduced, organometallic) which determine their mobility and toxicity. Determination of chemical speciation (identification of different chemical forms) provides much more complete information for a better understanding of the behavior and the potential impact on the environment. In this work we present the results of methodological research on the extraction of sequential forms of selenium in the soil and the coupling of analytical methods capable of identifying very small amounts of selenium in soils An efficient scheme of sequential extractions forms of selenium (SES) consisting in atomic absorption spectrometry coupled with hydride generation (HGAAS) has been developed into five experimental steps, detailed in the paper. This operational scheme has been applied to the analysis of chemical speciation in the following areas: the Baragan Plain and Central Dobrogea of Romania.
STUDY OF GAS SEPARATION PROCESS BY DYNAMIC ADSORPTION IN FIXED BED
Stelian Petrescu*, Marius Sebastian Secula, Maria Spiridon, Ioan Solomon
An experimental study of mass transfer at gas separation by dynamic adsorption in fixed bed of impregnated silica gel is presented in this work. By means of a mathematical model based on constants and coefficient easy to evaluate, the distributions of adsorbate concentration in gas and solid phases were determined as a function of time and throughout the height of the fixed bed, under isothermal conditions. With this aim, water vapors from air were adsorbed in a fixed bed of impregnated silica gel. The values of the volumetric mass transfer coefficient, Kv, were determined experimentally at several values of air superficial velocity, an air relative humidity of 69%, at 38 °C. The influence of the gas flow velocity and initial water concentration in adsorbent on the distribution of water concentration in both phases was established as a function of time and throughout the height of the fixed bed. The results obtained allow one to determination of the local adsorption rate.
CHEMICAL STUDY AND ANTIMICROBIAL ACTIVITIES OF VOLATILE EXTRACTS FROM FRESH LEAVES OF CRASSOCEPHALUM RUBENS (JUSS & JACK) S. MOORE AGAINST FOOD-BORNE PATHOGENS
Boniface Yehouenou(1), Valentin Wotto(1), Honoré Bankole(2), Philippe Sessou(1), Jean-Pierre Noudogbessi(1), Dominique Sohounhloue(1)*
The present work has studied the chemical composition of the essential oil (EO) extracted from the fresh leaves of Crassocephalum rubens and tested its efficacy against some pathogenic microorganisms isolated from common foods largely consumed, which had been incriminated as responsible of food infections and toxi-infections. The chemical composition of the essential oil extracted from the fresh leaves of Crassocephalum rubens, has revealed the presence of limonene (48.8%), myrcene (30.7%), E-(ß)-ocimene (7.4%) and a-thujene (4.6%) as the main components. In addition some oxygenated components had been identified. They are linalool, terpinen-4-ol, p-cymen-8-ol, E-nerolidiol and E-bisabol-11-ol. The Minimal Inhibitory Concentration (MIC) determined on some bacteria Gram+ (Staphylococcus aureus, Streptococcus faecalis), bacteria Gram- (Escherichia coli, Salmonella typhi) and against a pathogenic yeast (Candida albicans) vary from 0.54 mg/mL to 4.38 mg/mL. The two Gram+ are more sensitive to the EO activity while the two Gram- less sensitive and Candida albicans relatively resistant to the EO activity.
CHROMATOGRAPHIC DETERMINATION OF CAFFEINE CONTENTS IN SOFT AND ENERGY DRINKS AVAILABLE ON THE ROMANIAN MARKET
Violeta Nour(1)*, Ion Trandafir(2), Mira Elena Ionica(2)
Caffeine is a stimulant that is commonly found in many foods and drinks that we consume. Concerns exist about the potential adverse health effects of high consumption of dietary caffeine, especially in children and pregnant women. Recommended caffeine intakes corresponding to no adverse health effects have been suggested recently for healthy adults (400 – 450 mg/day), for women contemplating pregnancy (300 mg/day), and for young children age 4 – 6 years (45 mg/day). Different brands of soft and energy carbonated beverages available on the Romanian market were analysed for caffeine by HPLC with a diode array UV-VIS detector at 217 nm. The column was a reverse phase C18 and the mobile phase consisted of potassium dihydrogen orthophosphate buffer (0.02 mol/L, pH 4.3) and acetonitrile (88:12, v/v). The caffeine contents in energy drink samples ranged from 16.82 mg/100 mL to 39.48 mg/100 mL while the carbonated soft drink group showed caffeine content in the range of 9.79 – 14.38 mg/100 mL. In addition, the concentrations of caffeine have been converted into the daily intake doses based on beverages consumption. The mean values of caffeine daily intakes were 124 mg and 49 mg through the ingestion of energy drinks and soft drinks, respectively.
EFFECT OF SOME TECHNOLOGICAL FACTORS ON THE CONTENT OF ACETALDEHYDE IN BEER
Nevjana Petkova, Gunka Jonkova*
The purpose of this work was to examine the influence of the temperature, the pitching rate of yeast and wort composition (Free Amino Nitrogen) on the content of acetaldehyde in beer. It is known, that higher fermentation temperatures stimulate the formation of acetaldehyde, as well as the higher rate of acetaldehyde reduction, leading to lower concentrations in the final beer. Beer produced with increased pitching rate of yeast (26 and 35 × 106 cells•mL-1), contains lower quantities of acetaldehyde as compared to the control beer. Lower content of a-amino nitrogen in result of substitution of 5 to 10% of the malt with rice, sugar or a combination of both does not lead to considerable differences in the acetaldehyde concentration in beer.
THE INFLUENCE OF THE ELECTROSTIMULATION PROCESS ON POST-MORTEM TRANSFORMATIONS OF THE ENERGY RESERVES OF BEEF MUSCLE<br/> L’INFLUENCE DE L’ELECTROSTIMULATION SUR LES TRANSFORMATIONS POST-MORTEM DES RESERVES ENERGETIQUES DU MUSCLE DE BŚUF
Felicia Dima*, Camelia Vizireanu
The experimental results show that electrical stimulation has a positive effect on the biochemical changes and technological properties of beef meat. Given the beneficial changes reported in the literature, we used a portable device for electrical stimulation of the beef carcasses that can be used in small size slaughterhouses.
STUDY ON MONITORING THE QUALITY OF FROZEN BEANS LONG TIME STORED<br/> ÉTUDE SUR LA SURVEILLANCE DE LA QUALITÉ DE POIS CONGELÉE, STOCKÉE A LONGTERMES
Felicia Dima*, Camelia Vizireanu, Daniela Istrati
The study was conducted in a cold store of a company in Tulcea and watched for a long time how storage affects the quality of frozen product "green peas" by storage conditions, in fact, the air temperature of storage. To reduce some of the drawbacks of frozen storage of bulk product it is blanched. Blanching operation greatly influences the quality of stored frozen peas, considerably reducing the surface microflora of the product and produces the thermal inactivation of enzymes. It was found that insufficient blanching treatment leads to changes in aroma and taste of the product, especially due to enzyme activity and pyruvate-decarboxilase and lypoxidasa, with the formation of volatile compounds like aldehydes and ketones, which cause taste and smelly of herbal products. Vitamin C content of green peas sustains a continuous degradation during storage, both due to variations in temperature and it’s sudden, but also because the pH, if blanching was incomplete.
INTERACTIONS BETWEEN (Me4N)2(C2O4)2SnPh2•H2O AND SnCl2•2H2O: (Me4N)2(C2O4)2SnPh2•2SnCl4 OR (Me4N)2(C2O4)2SnCl2•2SnPhCl3 ? THE MÖSSBAUER EFFECT SOLUTION
Hayat Qamar Kane, Libasse Diop*
The study of the interactions between (Me4N)2(C2O4)SnPh2•H2O and SnCl2•2H2O in EtOH has yielded a trinuclear adduct which Mössbauer study has allowed to choose (Me4N)2(C2O4)2SnCl2•2SnPhCl3 rather than (Me4N)2(C2O4)2SnPh2•2SnCl4 for formula, the oxalate anion behaving as a bichelating ligand, the environment around the tin (IV) centre being octahedral.
BUFFERED ACETYLSALICYLIC ACID TABLETS (BASAT) DEVELOPMENT<br/> DEVELOPPEMENT DES COMPRIMES AVEC ACIDE ACETYLSALICILIQUE TAMPONNEES (AAST)
Florentina N. Roncea(1)*, Radu G. Cazacincu(2)
On the Romanian market there are several buffered acetylsalycilic acid tablets (BASAT), made by different producers that use the same acetylsalycilic acid quantity (500 mg/tablet) but use different agents like calcium gluconate (150 mg/tablet) or calcium carbonate (250 mg/tablet). The objective of this work is to obtain an optimal formulation for BASAT. Four different BASAT formulations have been obtained by wet granulation followed by compression. These formulations have been submitted to control tests as indicated by Pharmacopoeias. All the four formulations correspond regarding organoleptic examination, mass uniformity, mechanical strength (mean values between 67.6 – 199.4 N), friability (0.1832 – 0.4612% compared to max. 1%), disintegration (33.6 – 76.66 s). The mechanical strength and disintegration for F3 are greater than for F1, F2, and F4. The neutralizing capacity (0.91 – 2.71 mEq HCl that can neutralize 325 mg acetylsalycilic acid) is according to Pharmacopoeia only for F3 and F4 formulations.