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61.
To prevent the degradation of the borehole and also the disintegration and dispersion of drilled cuttings, different shale stabilizing additives are used in water‐based drilling fluids (WBFs). Glycols, poly(ethylene glycol), glycerols, and polyglycerol derivatives, also called polyols, have been used to inhibit shales containing reactive clays in WBF. These additives are normally used in conjunction with KCl to reduce clay swelling and dispersion of drilled cuttings. Highly branched polymers have become an important field in current polymer science. Such materials typically exhibit compact, globular structures in combination with an exceptionally high number of sites with functional groups. They have unique properties that differ significantly from their linear counterparts, and the hyperbranched polyglycerol (hPG) is an important hyperbranched polymer that can be produced from an environmentally benign monomer, the glycerol carbonate. In this article, the clay inhibitive properties of hPG were evaluated by different test methods including bentonite inhibition test, cuttings recovery, and X‐ray diffraction measurements. The results show that the hPG has a great potential to be used as an environmental friendly inhibitor additive in WBFs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40384.  相似文献   
62.
The drilling of petroleum wells requires the use of suitable drilling fluids to ensure efficient operation without causing rock damage. Specific polymers have been used to control infiltration during drilling, to reduce operational problems. In this study, spherical microparticles of poly(methyl methacrylate‐co‐vinyl acetate) were synthesized (by suspension polymerization), characterized, and evaluated in terms of their performance in controlling filtrate loss of aqueous fluids. A filter press test with ceramic disk, simulating the rock, was used. The performance of the synthesized materials was compared with commercial polymers. It was observed that the performance of the material is directly associated with the relation between particle size and pore size of the rock specimen. Furthermore, for a suitable particle size, the rubbery characteristic of the material produces a more efficient filter cake, for filtrate control. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40646.  相似文献   
63.
A study of chlorophyll and carotenoid composition of nine single-variety virgin olive oils from the main Spanish producing regions has shown differences depending on variety and ripening degree of the fruits. Pheophytin a was the major pigment in all the oils studied (44–58% total pigments), followed by lutein (18–38%) and β-carotene (6–17%). The chlorophyll pigments group also included pheophytin b and in some cases chlorophylls a and b . The carotenoid fraction also included the xanthophylls neoxanthin, violaxanthin, luteoxanthin, antheraxanthin, mutatoxanthin and β-cryptoxanthin. The mean provitamin A activity of the oils was 260 μg kg−1 expressed as retinol equivalent. cis -α-Carotene (tentative), mono- and di-esterified xanthophylls and pheophorbide a were pigments exclusive to Arbequina variety, a fact that could be used as a chemo-taxonomic differentiator of the oils of this variety. The ratio between the chlorophyll fraction and the carotenoid fraction was maintained in most cases around 1, demonstrating that the green and yellow fractions were in balance, notwithstanding their greater or lesser total pigment content. The considerable range in the lutein/β-carotene ratio (between 1·3 and 5·1 depending on variety) makes this ratio a differentiator of single-variety oils. Despite the different sources of the oils, some general trends have been shown which suggest what chlorophyll and carotenoid pigments should be expected in an olive oil so as to include it within the denomination ‘virgin’.  相似文献   
64.
The increasing importance of sustainability in energy production has led to a global commitment to the use of fuels derived from renewable biological sources, such as biodiesel produced from plant crops or biomass residues, that do not compete with human food for their production. For a biofuel to be considered biodiesel, it must satisfy the specifications described in the UNE 14214, with the UNE-EN 14103 referring to the determination of fatty acid methyl ester content. This standard applies gas chromatography as an analytical technique. Gas chromatography is a widely used technique in the analysis of methyl ester although it has a number of drawbacks such as: long analysis times, a high consumption of high-quality gases and internal standards, does not allow the analysis of different compounds with the same column, etc. From an industrial production point of view, is necessary to know the fatty acid methyl ester content in biodiesel samples quickly. This paper studies the development of an analytical method using Fourier transform infrared spectroscopy (FTIR) as alternative to gas chromatography (GC), since it is a simple, rapid, and precise analytical technique to quantify fatty acid methyl ester content in biofuel samples.  相似文献   
65.
Fetal stress is known to increase susceptibility to cardiometabolic diseases and hypertension in adult age in a process known as fetal programming. This study investigated the relationship between vascular RAS, oxidative damage and remodeling in fetal programming. Six-month old Sprague-Dawley offspring from mothers that were fed ad libitum (CONTROL) or with 50% intake during the second half of gestation (maternal undernutrition, MUN) were used. qPCR or immunohistochemistry were used to obtain the expression of receptors and enzymes. Plasma levels of carbonyls were measured by spectrophotometry. In mesenteric arteries from MUN rats we detected an upregulation of ACE, ACE2, AT1 receptors and NADPH oxidase, and lower expression of AT2, Mas and MrgD receptors compared to CONTROL. Systolic and diastolic blood pressure and plasma levels of carbonyls were higher in MUN than in CONTROL. Vascular morphology evidenced an increased media/lumen ratio and adventitia/lumen ratio, and more connective tissue in MUN compared to CONTROL. In conclusion, fetal undernutrition indices RAS alterations and oxidative damage which may contribute to the remodeling of mesenteric arteries, and increase the risk of adverse cardiovascular events and hypertension.  相似文献   
66.
On May 4th,2006,the international publication of a patentapplicationtitled“alloyed zinc powders for alkaline batteries withhigh Pyknometer density”WO2006/045470 A1[1],appeared·Theintention of this investigation was to see whether it is possible torepro…  相似文献   
67.
Mushrooms are very perishable foods due to their high susceptibility to moisture loss, changes in color and texture, or microbiological spoilage. Drying is considered as the most appropriate method to prevent these alterations, but it has some limitations, such as shrinkage, enzymatic and non-enzymatic browning reactions, and oxidation of lipids and vitamins. According to previous studies, irradiation might effectively attenuate the undesirable changes caused by drying process, ensuring also higher shelf-life of mushrooms and their decontamination. Electron-beam irradiation presents some technological advantages, since it allows higher dose rates and the possibility to be used in most foods/or thin products in a short period. Herein, the combined effects of electron-beam irradiation (0, 0.5, 1 and 6 kGy) and storage time (0, 6 and 12 months) were evaluated by measuring changes in nutritional parameters, namely, free sugars, tocopherols, fatty acids and antioxidant activity. As indicated by linear discriminant analysis, storage time had a higher effect on all the evaluated parameters, except fatty acids, which suffer significant changes with both factors. Overall, the obtained results indicate that electron-beam irradiation might be considered as a suitable technique, allowing long-lasting conservation periods while reducing changes induced by drying treatment.  相似文献   
68.
Honey is a highly consumed natural product, not only for its taste and nutritional value, but also for its health benefits. Owing to characteristics that are essentially or exclusively related to the specific region or particular local environment and flora, honey can be classified as a premium product generally perceived as a high‐quality and valued product because of its desirable flavor and taste. Consequently, honey has been a target of adulteration through inappropriate/fraudulent production practices and mislabeling origin. Globally, authentication of honey covers 2 main aspects: the production, with main issues related to sugar syrup addition, filtration, thermal treatment, and water content; and the labeled origin (geographical and/or botanical) and “organic” provenance. This review addresses all those issues, focusing on the approaches to detect the different types of honey adulteration. Due to the complex nature of honey and to the different types of adulteration, its authentication has been challenging and prompted the development of several advanced analytical approaches. Therefore, an updated, critical, and extensive overview on the current and advanced analytical methods targeting markers of adulteration/authenticity, including nontarget fingerprint approaches will be provided. The most recent advances on molecular, chromatographic, and spectroscopic methodologies will be described, emphasizing their pros and cons for the identification of botanical and geographical origins.  相似文献   
69.
In silico comparison of 34 putative pks genes in Aspergillus niger strain CBS 513.88 versus A. niger strain ATCC 1015 genome revealed significant nucleotide identity (>95% covering a minimum of 99% of the gene sequence) for 31 of these genes (approximately 91%). A. niger CBS 513.88 harbors three putative pks genes (An01g01130, An11g05940, and An15g07920), for which nucleotide identity was not found in A. niger ATCC 1015. To compare the results of the in silico analysis with the in vivo situation, experimental data were obtained for a large number of A. niger strains obtained from different substrates and geographical regions. Three putative pks genes that were found to be variable between the two A. niger strains using bioinformatics tools were in fact strain-specific genes based on experimental data. The PCR amplification signals for the An01g01130, An11g05940, and An15g07920 pks genes were detected in only 97%, 71%, and 26% of the strains, respectively. Southern blot analyses confirmed the PCR data. Because one of the strain-specific pks genes (An15g07920) is located in a putative ochratoxin cluster, we focused our investigation on that region. We assessed the ochratoxin production capability of the 119 A. niger strains and found a positive association between the presence of this pks gene and the capability of the respective strain to produce ochratoxin.  相似文献   
70.
Residues of pesticides in food are influenced by processing such as fermentation. Reviewing the extensive literature showed that in most cases, this step leads to large reductions in original residue levels in the fermented food, with the formation of new pesticide by-products. The behavior of residues in fermentation can be rationalized in terms of the physical-chemical properties of the pesticide and the nature of the process. In addition, the presence of pesticides decrease the growth rate of fermentative microbiota (yeasts and bacterias), which provokes stuck and sluggish fermentations. These changes have in consequence repercussions on several aspects of food sensory quality (physical-chemical properties, polyphenolic content, and aromatic profile) of fermented food. The main aim of this review is to deal with all these topics to propose challenging needs in science-based quality management of pesticides residues in food.  相似文献   
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