A thermoelastic diffusion theory with microtemperatures and microconcentrations

This article is concerned with a nonlinear theory of thermodynamics for elastic materials in which the particles are subjected to classical displacement, temperature, and mass diffusion fields and whose microelements possess microtemperatures and microconcentrations. The equations of the linear theory are also obtained. It is shown that there exists coupling between temperature, chemical potential, microtemperatures, and microconcentrations even for isotropic bodies. With the help of the semigroup theory of linear operators, we prove the well-posedness of the linear anisotropic problem and we study the asymptotic behavior of the solutions.     

Mechanical characterization of triaxially braided hybrid composites

The use of advanced composites has been expanded to the oil and gas industry. One of the newly developed technologies is in composite coiled tubing that offers the potential of exceeding the performance of metallic tubings. The high strains due to bending and the complex state of stress in these tubes necessitate the better understanding of the correlation between fiber architecture and tube performance. Braided composites can withstand high bending deformation without severe degradation of properties. In this study, braided hybrid composites are presented as an option for achieving high performance coiled tubing under tensile and flexural loads. The effects of material and fabric microstructural parameters on the mechanical behavior of braided hybrid composites are studied. The mechanical characterization of triaxially braided composites has identified the influence of the mechanical properties of the axial yarn, the axial yarn volume fraction, and the braid angle. Overall, this study provides a sound knowledge base for the design, fabrication, and characterization of triaxially braided composites for coiled tubing applications in the petroleum industry.     

Thermal Decomposition of 2-Nitrobenzoic Acid

The thermal decomposition of 2-nitrobenzoic acid is investigated by means of adiabatic and quasi-isothermal calorimetry. The decomposition process develops according to zero order kinetics which gives substantial support to the intervention of vapour-phase reaction. The apparent activation energy of 144·8 kJ mol⁻¹ is evaluated. Chemical analysis gives support to the proposal of reliable reaction mechanisms. © 1997 SCI.     

Antioxidant activity of virgin olive oil phenolic compounds in a micellar system†

The antioxidant activity of two virgin olive oils, obtained from the same olive (Olea europaea sativa) batch but processed with different hammer crushing conditions, was evaluated by measuring their protective action towards linoleic acid peroxidation in a micellar system. The antioxidant efficiency (AE) of the oil phenolic fraction was higher when the olives were processed with a higher hammer crusher rotation rate. HPLC analysis demonstrated that one of the main derivatives of oleuropein, indicated as 3,4-DHPEA-EDA (the dialdehydic form of elenolic acid linked with 3,4-dihydroxyphenylethanol), is present only in the oil with higher AE. 3,4-DHPEA-EDA showed the greatest antioxidant ability among virgin olive oil phenols. Its greater efficiency in the micellar system in comparison with 3,4-dihydroxyphenylethanol (3,4-DHPEA) is related to its greater lipophilicity. It is suggested that the behaviour in the water–micellar environment is representative of that in a real system such as tomato-based sauce with added virgin olive oil. © 1999 Society of Chemical Industry     

VDACs Post-Translational Modifications Discovery by Mass Spectrometry: Impact on Their Hub Function

VDAC (voltage-dependent anion selective channel) proteins, also known as mitochondrial porins, are the most abundant proteins of the outer mitochondrial membrane (OMM), where they play a vital role in various cellular processes, in the regulation of metabolism, and in survival pathways. There is increasing consensus about their function as a cellular hub, connecting bioenergetics functions to the rest of the cell. The structural characterization of VDACs presents challenging issues due to their very high hydrophobicity, low solubility, the difficulty to separate them from other mitochondrial proteins of similar hydrophobicity and the practical impossibility to isolate each single isoform. Consequently, it is necessary to analyze them as components of a relatively complex mixture. Due to the experimental difficulties in their structural characterization, post-translational modifications (PTMs) of VDAC proteins represent a little explored field. Only in recent years, the increasing number of tools aimed at identifying and quantifying PTMs has allowed to increase our knowledge in this field and in the mechanisms that regulate functions and interactions of mitochondrial porins. In particular, the development of nano-reversed phase ultra-high performance liquid chromatography (nanoRP-UHPLC) and ultra-sensitive high-resolution mass spectrometry (HRMS) methods has played a key role in this field. The findings obtained on VDAC PTMs using such methodologies, which permitted an in-depth characterization of these very hydrophobic trans-membrane pore proteins, are summarized in this review.     

电弧炉中废钢料的元素监测

评估了激光诱导击穿光谱（LIBS）在废钢料分析中的使用,以用于电弧炉中废钢料的元素监测。开发了一个LIBS原型用于现场试验,并将其安装在位于废钢料填充区和电弧炉之间的钟摆式输送槽上。LIBS原型距离电弧炉大约25 m。废钢料填充的钟摆式输送槽的宽度和深度分别为大约2 m和1 m。调整废钢料的平均速率在0.3～5.5 m/min的范围内,使之满足电弧炉的装填要求,从而使废钢料的生产能力达到100 t/h。在安装地点,低合金废钢料中高含量硅的检测基本上对电弧炉控制的改进很有帮助。由于测量体积受限在600×600×180 mm³,研发的原型仅检测了一小部分的钢料表面。但是,在线LIBS测量还是显示了在工业环境下测定高硅废钢料样品的能力。为了拓展在加料、过程控制及管理上的应用,应增加测量体积从而进一步提高其性能。     

Production of biogenic amines by lactic acid bacteria: screening by PCR, thin-layer chromatography, and high-performance liquid chromatography of strains isolated from wine and must

Biogenic amines are frequently found in wine and other fermented food. We investigated the ability of 133 strains of lactic acid bacteria isolated from musts and wines of different origins to produce histamine, tyramine, and putrescine. We detected the genes responsible for encoding the corresponding amino acid decarboxylases through PCR assays using two primer sets for every gene: histidine decarboxylase (hdc), tyrosine decarboxylase (tdc), and ornithine decarboxylase (odc); these primers were taken from the literature or designed by us. Only one strain of Lactobacillus hilgardii was shown to possess the hdc gene, whereas four strains of Lactobacillus brevis had the tdc gene. None of the Oenococcus oeni strains, the main agents of malolactic fermentation, was a biogenic amine producer. All PCR amplicon band-positive results were confirmed by thin-layer chromatography and high-performance liquid chromatography analyses.     

Assessment of edible marine species in the Adriatic Sea for contamination from polychlorinated biphenyls and organochlorine insecticides

It is estimated that 90% of human exposure to persistent organic pollutants is through food, and fish and shellfish represent an important source of contamination for polychlorinated biphenyls (PCBs) and organochlorine insecticides. To evaluate the levels of seafood contamination coming from the central Adriatic Sea, Italy, a study involving several pools of shellfish, crustaceans, and fish was carried out. Several marine species were selected by their abundance, wide distribution, and common use in the Italian diet and sampled and analyzed during 2004. The concentration of total (sigma) PCBs exceeded that of total dichlorodiphenyltrichloroethanes (DDTs) in all samples. Atlantic mackerel showed the highest concentrations of PCBs, ranging from 514 to 1772 ng/g of fat weight, and DDTs, ranging from 52 to 656 ng/g of fat weight. The lowest concentrations of PCBs and DDTs were found in cephalopods and mussels. Despite this, to protect human health from these pollutants, legal limits have been established for fish and shellfish for DDTs but not PCBs. The most common representative PCB congeners, in all species, were PCB 153 and PCB 138; the most common DDT was p,p'-dichlorodiphenyldichloroethylene.