Influence of the alkyl chain length of HSO3-R-MCM-41 on the esterification of glycerol with fatty acids

Ordered mesoporous materials functionalized with alkyl sulfonic acid groups have been proved to be efficient catalysts for esterification. In this paper we report on the synthesis and characterization of new materials containing simultaneously alkyl groups (vinyl, chloromethyl), that have been sulfonated in a post-synthesis step, and methyl groups. Different techniques have been used to characterize the obtained materials: XRD, TEM, elemental analysis, nitrogen adsorption, TGA, ²⁹Si and ¹³C MAS NMR. Finally, the influence of the different synthesis parameters and functional groups on the behavior of the catalysts in the reaction of esterification of glycerol with lauric and oleic acids has been studied. The catalytic performance of the resulting HSO₃-ethyl-MCM-41, HSO₃-ethyl/methyl-MCM-41 and HSO₃-methyl-MCM-41 new materials is also compared to those of HSO₃-phenyl/methyl-MCM-41 and HSO₃-propyl/methyl-MCM-41 synthesized previously. It has been demonstrated that an optimum balance among parameters such as nature of the organic group which support the sulfonic acid, distance between the sulfonic group and the silica surface, average pore size of the material, etc., allows to obtain catalysts with improved activity and selectivity for these reactions.     

Factors influencing sources cited by scientists: A case study for Cuba

A collection of 1316 articles authored by Cuban scientists and published in the period 1950 to 1983 was assembled. The 18 991 bibliographic references in these papers were examined to identify factors that might influence the sources cited by Cuban scientists over the entire period. Degree of collaboration, place of publication and subject matter were among the factors considered. The major objective was to study the effect that the change in political alignment of Cuba (from Western bloc to Eastern bloc influence) has had on the sources cited. It was found that citation to Eastern bloc countries has greatly increased in the period since Castro assumed power. However, no corresponding decline in citation to Western bloc countries can be discerned.     

The role of taste in dietary self-selection in rats.

Conducted 3 experiments with 78 male albino Harlan and Sprague-Dawley rats in which Ss were subjected to 2 degrees of gustatory deafferentation—either the chorda tympani was sectioned alone or in combination with the glossopharyngeal nerve and the pharyngeal branch of the vagus. Ss were then presented with 2 diets, only 1 of which contained protein. Findings reveal that, after surgery, deficits were observed in body weight, food and water intake, and diet selection that were proportional to the extent of deafferentation. Approximately 76% of the Ss increased protein and decreased carbohydrate intake, but all Ss continued to select a nutritionally balanced diet (Exp I). When subjected to a nutritional challenge of intragastric protein or carbohydrate supplementation, the Ss compensated for calories and nutrients by selectively adjusting oral intake (Exp II). In saccharin preference tests, the preference as well as the total consumption of the test solutions was reduced (Exp III). Results support the hypothesis that dietary selection pattern of an animal not only reflects intrinsic factors (metabolic/physiological state) but also extrinsic factors such as the pallatability and accessibility of the diet. Findings are contrasted to the effects of oral somatosensory deafferentation and are interpreted as a change in preference within the limits of metabolic requirements. The different roles/mechanisms of the 2 sensory systems in regard to dietary self-selection are discussed. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radical-scavenging activity of Aegean Sea marine algae

In the present work, thirteen algae from the Aegean Sea were examined for radical-scavenging activity (RSA) using the DPPH and chemiluminescence (CL) tests. Extracts of the brown alga Taonia atomaria exhibited the best RSA in comparison to the extracts of the other investigated species and approached the activity of powerful antioxidant standards. Column chromatography separation of T. atomaria extract, followed by preparative HPLC, resulted in the isolation of six metabolites, which were identified by spectral analyses (¹H NMR, ¹³C NMR and MS). The isolated metabolites taondiol, isoepitaondiol, stypodiol, stypoldione, sargaquinone and sargaol were found to possess marked RSA.     

Effects of milk high pressure homogenization on biogenic amine accumulation during ripening of ovine and bovine Italian cheeses

The aim of this work was to evaluate the biogenic amine (BA) content during the ripening of both bovine and ovine cheeses obtained using milk subjected to a homogenization treatment at 100 MPa before cheese-making. The data obtained were compared with those from cheeses produced by the same milks without any treatment or thermized. The results showed that both microbial ecology and BA concentrations of cheeses during ripening were significantly influenced by the type of milk used for cheese-making and by the treatment applied to the raw materials. In particular, the microbial counts found in Caciotta indicated that the high pressure homogenization (HPH) of milk significantly reduced the presence of the yeasts, Micrococcaceae and lactobacilli at the end of ripening. On the other hand, the HPH treatment of milk favoured the proliferation of yeasts in ovine cheese. Moreover, the ovine cheeses were characterized by a remarkably higher accumulation of BA than bovine cheeses. However, the HPH treatment of milk was able to drastically reduce the biogenic amine concentrations in both cheese typologies at the end of ripening.     

Development of an HS-SPME-GC method to determine the methyl anthranilate in Citrus honeys

An efficient and simple method for determination of methyl anthranilate (MA) in Citrus spp. honeys by headspace-solid-phase microextraction-gas chromatography (HS-SPME-GC) was developed and validated. Experimental design was used to investigate the effects of the principal extraction parameters. The central composite design (CCD) and the desirability function were used to find the experimental conditions providing the optimal HS-SPME result. Validation was carried out in terms of specificity, linearity, limit of detection (LOD) and quantitation (LOQ) (0.149 and 0.324 μg/g, respectively), method precision (RSD 7%), LOQ precision (RSD 6.5%), and was resulted accurate and robust. Finally, the applicability of the method to the determination of MA in a number of commercial Citrus spp. honey samples was demonstrated, the content ranged from 0.63 to 3.26 μg/g.     

Bioactivity of Flavonoids on Insulin‐Secreting Cells

ABSTRACT: Flavonoids are usually found in fruits and other plant organs and therefore widely consumed. They are antioxidants, anti‐inflammatory, anticarcinogenic, and protective against coronary disease and metabolic disorders. These beneficial effects make them good candidates for the development of new functional foods with potential protective/preventive properties against several diseases. We must consider that this fact could lead to a higher intake of some of these flavonoids. Most of the studies concerning their beneficial effects showed peripheral activity of these molecules, but there is no clear information about their central effects on a key organ on metabolic control: the endocrine pancreas. The pancreas has an endocrine function of major importance to regulate nutrient metabolism, such as control of glucose homeostasis via insulin and glucagon secretion. Its importance in whole body nutrient equilibrium is highlighted by the fact that several pathologies, such as type 1 and/or 2 diabetes, are related at some point to a pancreatic cell deregulation. In this review, we compile the most relevant results concerning the effects of flavonoids on several aspects of pancreatic functionality. Studies using animals with drug‐induced diabetes support the hypothesis that flavonoids can ameliorate this pathogenesis. The great diversity of flavonoid structures makes it difficult to establish common effects in the pancreas. Published data suggest that there might be direct effects of flavonoids on insulin secretion, as well as on prevention of beta‐cell apoptosis, and they could even act via modulation of proliferation. The mechanisms of action involve mainly their antioxidant properties, but other pathways might also take place.     

General purpose software for probability computations—A virtual machine approach

The application of probability techniques in structural engineering has seen ample development in the last decade. Yet, the software used for engineering probability computations often lacks generality. The functional needs to be satisfied by general purpose software for engineering applications of probability methods are presented. An analysis of these needs suggests a software design philosophy based on the concept of a software virtual machine for probability computations. The virtual machine architecture and software design are explained. An example problem, in seismic risk analysis, solved with software based on this design is described.     

DETERMINATION OF β-GLUCAN IN WORT AND BEER BY ITS BINDING WITH CALCOFLUOR,USING A FLUORIMETRIC FLOW-INJECTION-ANALYSIS (FIA) METHOD

The FIA-fluorimetric methods for the determination of β-glucan in worts and beers have been investigated, modified and improved. Fluorescence is excited by using a mercury lamp and a 338 nm band-pass excitation filter, and detected using a 425 nm long-pass emission filter. It has been found that an increase of the ionic strength of the eluent, up to a maxium of 1% Sodium Chloride, increases the range of β-glucan molecular weights effectively bound by Calcofluor. The influence of the low molecular weight components of wort and beer: dextrins, aminoacids, etc, has been studied and found that their effect is negligible. The interference of wort and beer colour on the measurement of β-glucan has been quantified and several approaches are given to overcome it. Thirty-six European beers have been analyzed for β-glucan content. The possible detection of the addition of exogenous β-glucanases to wort and beer is discussed.     

Exposure of Human Models in the Near and Far Field?A Comparison

The specific absorption rate (SAR) was measured in over 650 locations in a full-scale model of man exposed in the far and near field of antennas at 350 and 915 MHz. The whole-body average, the body-parts average, and the distributions of the SAR's are compared for three wave polarizations for the far and the near-field exposures. Effects on the energy deposition of the antenna type, gain, and location in the near field are discussed.