TERNARY NaCl+LiCl+H2O MIXED ELECTROLYTE SYSTEM: DETERMINATION OF ACTIVITY COEFFICIENTS BASED ON POTENTIOMETRIC METHOD

The mean activity coefficients for NaCl in a ternary electrolyte system were determined by the potentiometric method, at 25°C, using a solvent polymeric (PVC) sodium-selective membrane electrode (Na⁺ ISE), containing N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide as ionophore, and combined with an Ag/AgCl electrode. The potentiometric measurements were performed at the same ionic strengths in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m₁/m₂ = 1, 10, 50, 100). The nonideal behavior of the ternary NaCl(m₁) + LiCl(m₂) + H₂O electrolyte system was described based on the Pitzer ion-interaction model for mixed salts over the ionic strength ranging from 0.01 up to about 4 mol/kg. Two- and three-particle Pitzer interaction parameters for a mixed electrolyte system were determined based on potentiometric data, and the critical role of potentiometric selectivity coefficient (K ₁₂) of ISE as limiting factor in the potentiometric measurements was analyzed.     

A synthesis of (arylthio-ethylidene)indolin-2-ones via S-arylation of oxoindolin-ethanethiolates with aryl halides

Aryl-sulfur bond formation between aryl halides and 1-(2-oxoindolin-3-ylidene)-2-aroylethanethiolates, prepared from isatin, 1-aryl-2-thiocyanatoethan-1-ones, and aryl halides, catalyzed by copper(I) iodide in DMF at 80°C afforded a nearly 1:1 mixture of (Z/E)-3-(2-oxo-2-aryl-1-(arylthio)ethylidene)indolin-2-ones, in good yields. The stereochemistry of these products has been confirmed by X-ray diffraction studies.     

Substance use and the paradox of good and bad attentional bias.

Habitual substance use is associated with attentional bias for stimuli related to the use. The current study tested whether individuals’ substance use can be predicted from their attentional bias for concern-related and substance-related stimuli. Participants (N = 71; 54% male) were selected among university students and the community. The study was conducted in Iran, in which alcohol consumption is illegal. Participants completed a substance use questionnaire and classic, substance-, and concern-related Stroop tests. The results show that after controlling for demographic variables and classic Stroop interference, increases in substance-related but decreases in concern-related reaction times predicted the amount of substances that had been consumed by the participants. Individuals’ attentional bias for both substance-related and substance-unrelated goals may be important in predicting substance use behavior. The implication of the findings for treatment prognosis has been discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lipoxygenase and hydroperoxide lyase activities in two olive varieties from Northern Italy

Lipoxygenase (LOX) and hydroperoxide lyase (HPL) activities were characterised in olive pulp microsomes from two cultivars (Ghiacciolo and Nostrana di Brisighella) from Northern Italy. LOX activity exhibited a maximum at pH 5.5 in both cultivars, and the highest value was found in cv Ghiacciolo. This was correlated with the higher total antioxidant capacity detected in cv Nostrana, rather than by a different LOX expression, as demonstrated by immunoblotting assay. Furthermore, isomer characterisation showed the predominance of 13‐hydroperoxides of linoleic acid (HPOD) in both cultivars, suggesting the occurrence of a 13‐LOX. HPL activity exhibited an optimum at pH 7.5 in the two cultivars, but was higher in cv Nostrana, as confirmed by the increased amount of hexanal production after 13‐HPOD addition. In addition, the constitutive aldehyde profile in cv Nostrana fruits were shown to be enriched in aldehydes too when compared to cv Ghiacciolo. These results suggest that the different features in the two olive cultivars are mainly due to genetic rather than environmental factors. Practical applications: In this paper we studied the lipoxygenase (LOX) and hydroperoxide lyase (HPL) activities, and the formation of their products (hydroperoxides and aldehydes) in microsomes extracted from olive pulp of two Italian cultivars. The study of LOX and HPL, belonging to the so‐called ‘oxylipin pathway’, has important implications on the aroma development in both fruit and oil. Thus, a better knowledge of the properties of these enzymes can be useful to improve the organoleptic features of the oil. In fact, ‘LOX pathway’ may play a positive role in the formation of pleasant flavours during the technological processes. The preliminary study of the activity of the LOX/HPL enzymes could represent an important tool to facilitate the varietal choice in order to improve oil quality.     

Modeling uncertainties in sodium spatial dispersion using a computational intelligence-based kriging method

Classical and geostatistical methods have been used to create continuous surfaces from sampled data. A common geostatistical method is kriging, which provides an accurate estimation based on the existing spatial structure of sample points. However, kriging is sensitive to errors in the input data, the dispersion of the sample points, and the fit of the model to the variogram. The purpose of this research is to develop a new method to address the uncertainties resulting from the input data and choice of model in the kriging method. In our approach, the existing uncertainties in the input data are modeled by fuzzy computations, and the variogram variables are optimized by a genetic algorithm. To test this new hybrid method, sodium contamination values in the Zanjan aquifer were used. The results show a general improvement in accuracy compared with the ordinary kriging method. Consideration of all equations and values in fuzzy computations highlights the complexity of the computation. Herein, the integration problems experienced by other researchers when trying to use fuzzy kriging are resolved.     

Hair mercury levels in pregnant women in Mahshahr, Iran: Fish consumption as a determinant of exposure

MeHg is a well-documented neurotoxicant even at low levels of exposure. Developing brain, in particular, is vulnerable to that. Through bioaccumulating to differing degrees in various fish species, it can have serious adverse effects on the development and functioning of the human central nervous system, especially during prenatal exposure. Therefore, the purpose of this study was to investigate mercury concentration in hair samples of pregnant women living in Mahshahr located in Khuzestan province, Iran. It assessed the association between fish consumption and specific characteristics that can influence exposure. From April to June 2008, 149 pregnant women were invited to participate in this study. An interview administered questionnaire was used to collect information about age, body weight, height, fish (fresh, canned and shrimp) consumption, pregnancy stage, residence duration, education level, family income and number of dental amalgam fillings. The obtained results showed that the geometric mean and range for hair total Hg concentration was 3.52 μg/g (0.44-53.56 μg/g). About 5.4% of mothers had hair total Hg levels in excess of 10 μg/g. Maternal hair mercury level was less than threshold level of WHO (5 μg/g). As expected, there was a clear increase in hair Hg with reported fresh marine fish consumption (p = 0.04). The highest mean for hair mercury level in a group who consumed fish several times per week, was 4.93 μg/g. Moreover, a significant effect of age and residential time on Hg concentration in the hair of the women was found. Pregnant women in Mahshahr consumed large amounts of fish; consequently, most of their offspring were prenatally exposed to moderately high levels of mercury. The results found suggest that pregnant women should decrease their fish consumption.     

Unlicensed motorcycling of high school adolescents in Dehaghan county (Isfahan Province of Iran)

Background

Unlicensed motorcycling increases the chances of accidents in adolescents. There are many behavioral and non-behavioral factors involved in adolescents’ unlicensed motorcycling which were not addressed in research yet completely.

Methods

The cross-sectional study aimed to determine prevalence and related factors of unlicensed motorcycling on 500 unlicensed male high school adolescents in Dehaghan, who entered in the study by census. Demographic and motorcycling information were collected via self-report questionnaire, and its content validity was approved by a panel of experts. The statistical analyses of the data included Pearson Correlation Coefficient, chi-square, independent samples t-test and ANOVA with Tukey post hoc test.

Results

The prevalence of unlicensed motorcycling among participants was 74.2% and mean age at first motorcycling experience was 11.97 ± 1.97 years ranged from 8 to 17. Of the motorcyclist participants, 59.6% owned their personal motorcycle. Most motorcycle passengers (62.8%) were adolescent’s friends, and the most frequently expressed reason for use of motorcycle was fun and entertainment (54.2%). Age at first motorcycling experience was lower among rural adolescents than urban adolescents. However, unlicensed motorcycling was more prevalent among urban adolescents than rural ones. The relationship between living status, father’s job, mother’s job and age at first motorcycling experience was insignificant (P > 0.05). However, mean age at first motorcycling experience among students of humanities, technical disciplines, and general first year was lower than that among students of natural sciences and math.

Conclusion

High prevalence of unlicensed motorcycling and significant role of family and social environments on adolescents’ high-risk motorcycling without license, is indicative of the need for interventions at all levels of peers, family, and schools and also establishing new driving regulations in Iran.     

Modified glassy carbon electrode with multiwall carbon nanotubes as a voltammetric sensor for determination of noscapine in biological and pharmaceutical samples

A simple and highly sensitive method is described for direct voltammetric determination of noscapine in blood and pharmaceutical sample. Glassy carbon electrode with effective method is modified with multiwall carbon nanotubes (MWNTs) to cause activation of multiwall carbon nanotubes structures for electrocatalyzes of noscapine oxidation. The cyclic voltammetric (CV) results indicated that MWNTs remarkably enhances electrocatalytic activity toward the oxidation of noscapine, which is leading to considerable improvement of anodic peak current for noscapine, and allows the development of a highly sensitive voltammetric sensor for detection of noscapine in pharmaceutical and clinical samples. Under the optimum condition, the calibration curve was linear in the concentration range 4.0 × 10⁻⁷–1.0 × 10⁻⁴ mol L⁻¹ with the detection limit of 8.0 × 10⁻⁸ mol L⁻¹ and relative standard deviation (R.S.D.%) lower than 1.0% (n = 5). Finally, some kinetic parameters were determined and multistep mechanism for oxidation of noscapine for first time was proposed.     

Surface functionalization of SBA-15 nanorods for anticancer drug delivery

SBA-15 nanorods with high surface area (1010 m² g⁻¹) were functionalized by post grafting method with three different alkoxysilanes including (3-aminopropyl) triethoxysilane (APTES), 3-[bis(2-hydroxyethyl)amino] propyl triethoxysilane (HAPS) and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane (AEPS). The prepared materials were used as nanocarriers for an anticancer drug (gemcitabine). The obtained samples were characterized by SAXS, elemental analysis, TGA, N₂ adsorption/desorption, SEM, TEM, FTIR and UV spectroscopies. The adsorption and release properties of all samples were investigated. It was found that the surface functionalization increases the interaction between the carrier and gemcitabine and results in the loading enhancement of the drug. In addition, the adsorption of gemcitabine on the modified mesoporous matrix depends on the type and the amount of alkoxysilanes groups. The maximum content of the deposited drug in the modified SBA-15 nanorods is close to 22 wt.%. The rate of the drug release from the modified samples containing NH₂ groups on their surfaces is pH dependent.