Effect of heating oxyhemoglobin and methemoglobin on microsomes oxidation

Hemoglobin (Hb) has been proposed to be a major pro-oxidant in raw and cooked meats. To understand the mechanisms and differentiate between the pro-oxidant and antioxidant potential of oxyhemoglobin (OxyHb) and methemoglobin (MetHb), their pro-oxidant activity, protein solubility, radical scavenging capacity, iron content and contribution of non-chelatable iron on lipid oxidation were determined as a function of thermal treatments. The ability of native OxyHb and MetHb to promote lipid oxidation was similar and higher than their corresponding OxyHb or MetHb heated at 68 and 90 °C but not different from those at 45 °C. The pro-oxidant activity of MetHb heated at 68 and 90 °C were similar whereas the pro-oxidant activity of OxyHb heated at 68 °C was higher than that heated at 90 °C. The decreased pro-oxidant activity of heat-denatured Hb was associated with a decrease in the solubility of heme iron while free iron showed little impact on the lipid oxidation.     

Simple and Fast Determination of Acrylamide and Metabolites in Potato Chips and Grilled Asparagus by Liquid Chromatography Coupled to Mass Spectrometry

The purpose of this study was to evaluate an analytical procedure for the determination of acrylamide in different starchy foods such as potato chips and grilled asparagus. The method is based on high-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (HPLC-QqQ-MS/MS). A solid–liquid extraction procedure, using water as extraction solvent, has been developed followed by a cleanup procedure based on solid-phase extraction (SPE) or dispersive solid-phase extraction (d-SPE). Polymeric cartridges (Oasis HLB) and aluminum oxide (Al₂O₃) were used for potato and asparagus matrices, respectively. The optimized procedures were validated, and limits of detection and quantitation were 4 and 12 μg/kg for potato chips and 2 and 5 μg/kg for grilled asparagus, respectively. Recoveries were evaluated, and good values were obtained, ranging from 90 to 117 % for potato chips and from 90 to 116 % for grilled asparagus. The method was applied to real samples, and concentrations ranged from 105 to 860 μg/kg in potato chips, whereas higher values were detected in grilled asparagus (from 292 to 1469 μg/kg). Furthermore, single-stage Orbitrap high-resolution mass spectrometry has been used for the putative identification of acrylamide-N-acetyl-S-(2-carbamoylethyl)-l-cysteine (AAMA) in urine.     

Screening of some Algerian medicinal plants for the phenolic compounds and their antioxidant activity

Since recent times, there is a growing interest in the food industry and in preventive health care for the development and evaluation of natural antioxidants from medicinal plant materials. In the present work we have investigated the antioxidant potency of phenolic compounds of 11 indigenous wild plant species from the Algerian Atlas commonly used in Arab folk medicine for a wide range of conditions. The antioxidant activity of each phenolic extracts has been assessed by using the Trolox Equivalent Antioxidant Capacity (TEAC) as a chemical test, and in a dynamic way by a biological assay based on whole blood resistance to free radical aggression. Of the 11 tested plants, 2 showed prominent antioxidant activity: Anthemis arvensis and Artemisia campestris. These plants had a very high level of Trolox equivalents and induced a strong delay of free radical-induced red blood cells hemolysis compared to antioxidant references. Artemisia campestris was the best inhibitor, its effect was far stronger than that of caffeic acid and was more than three times as high as ascorbic acid and two times higher than α-tocopherol efficiency. HPLC analysis showed a good correlation between the antioxidant activity and hydroxycinnamic derivatives. These preliminary results on the in vitro protection of blood against oxidative stress emphasized the benefit of the phenolic compounds of these medicinal plants. Our results enable us to proceed towards more detailed chemical and pharmacological understanding of these plant materials and show the interest of natural antioxidant in medicinal plants for the prevention of much free radical-mediated pathology.     

Polar pollutants entry into the water cycle by municipal wastewater: a European perspective

The effluents of eight municipal wastewater treatment plants (WWTP) in Western Europe were analyzed by liquid-chromatography-mass spectrometry for the occurrence of 36 polar pollutants, comprising household and industrial chemicals, pharmaceuticals, and personal care products. In a long-term study of the effluents of three WWTP over 10 months, sulfophenyl carboxylates and ethylene diamino tetraacetate (EDTA) were detected above 10 microg/L on average, while benzotriazoles, benzothiazole-2-sulfonate, diclofenac, and carbamazepine showed mean concentrations of 1-10 microg/L, followed by some flame retardants, naphthalene disulfonates, and personal care products in the range of 0.1-1 microg/L. Half of the determined compounds were not significantly removed in tertiary wastewater treatment. By dividing the effluent concentration of a compound by its relative removal in WWTP a water cycle spreading index (WCSI) was calculated for each compound. We propose that this index provides a measure for the potential of a polar compound to spread along a partially closed water cycle after discharge with municipal wastewater and to occur in raw waters used for drinking water production. Polar pollutants in surface water samples of different catchments showed increasing concentration for compounds with increasing WCSI.     

Freezing of meat raw materials affects tyramine and diamine accumulation in spontaneously fermented sausages

Biogenic amine accumulation was studied in spontaneously fermented sausages (Fuet) manufactured from unfrozen-fresh meat (U-sausages) and frozen-thawed meat (F-sausages). The aim was to investigate whether the frozen storage of raw materials affects the microbial composition and its aminogenic activity during sausage fermentation. Tyramine was the major amine in all sausages. Although the final levels were similar, tyramine accumulated more rapidly in F-sausages, which contained putrescine as the second amine. By contrast, U-sausages accumulated much more cadaverine than putrescine. F-sausages showed a slightly lower pH and free amino acid content as well as higher counts of technological flora (lactic acid and gram positive catalase positive bacteria) and lower counts of enterobacteria. Therefore, to freeze the meat raw materials for few days before sausage manufacture could be a useful practice, especially for the artisan fermented sausages (without starter), because it helps to reduce enterobacteria development and cadaverine production.     

Electrochemical synthesis and characterization of carbon-supported Pt and Pt–Ru nanoparticles with Cu cores for CO and methanol oxidation in polymer electrolyte fuel cells

Pt and Pt–Ru shells on Cu cores supported on Vulcan carbon XC72R have been synthesized and tested as possible anode electrocatalysts for polymer electrolyte fuel cells. Pt(Cu)/C was prepared by Cu electrodeposition on the black carbon support at constant potential followed by Pt deposition on Cu by galvanic exchange, whereas Pt–Ru(Cu)/C was prepared by spontaneous deposition of Ru species on Pt(Cu)/C. The corresponding cyclic voltammograms in 0.5 M H₂SO₄ solution showed the hydrogen adsorption/desorption peaks and no Cu oxidation. The respective CO stripping peak potentials of Pt(Cu)/C and Pt–Ru(Cu)/C were about 0.1 and 0.2 V more negative than those corresponding to Pt/C and Ru-decorated Pt/C. The best conditions for CO oxidation were found for Cu deposition potentials between −0.2 and −0.4 V vs. Ag/AgCl/KCl(sat). The Pt economy of the Pt–Ru(Cu)/C system was proved for the methanol oxidation, with specific currents more than twice those obtained on the Ru-decorated commercial Pt/C catalysts.     

Individual Voltage Balancing Strategy for PWM Cascaded H-Bridge Converter-Based STATCOM

This paper presents a new control method for cascaded connected H-bridge converter-based static compensators. These converters have classically been commutated at fundamental line frequencies, but the evolution of power semiconductors has allowed the increase of switching frequencies and power ratings of these devices, permitting the use of pulsewidth modulation techniques. This paper mainly focuses on dc-bus voltage balancing problems and proposes a new control technique (individual voltage balancing strategy), which solves these balancing problems, maintaining the delivered reactive power equally distributed among all the H-bridges of the converter.     

Chitosan derivatives with thickening properties obtained by reductive alkylation

Chitosan derivatives were prepared by reductive alkylation using glutaraldehyde and 3-amino-1-propanol. The reducing agent used was sodium borohydride. Tests of solubility, stability and viscosity were performed to evaluate the effect of the molar ratio of the reactants and the presence of nitrogen in the reaction system. The ¹H NMR characterization of chitosan derivatives confirmed the presence of hydrophobic groups grafted onto the chitosan backbone. The rheological behavior of the polymers was studied as a function of polymer concentration, temperature and ionic strength of the medium. It was observed that the chemical modification of chitosan resulted in derivatives with thickening action, and the polymer solubility in acetic acid aqueous solution decreased with the increase of the glutaraldehyde and 3-amino-1-propanol molar ratio in relation to chitosan. The atmosphere of nitrogen and a larger amount of reducing agent in the reaction system contributed to the increase in solubility, stability and viscosity of the polymer in solution. The chitosan derivative solutions were significantly more viscous than the chitosan solution and showed higher thermal stability in the presence of salt, which could be explained by the hydrophobic groups grafted onto the chitosan backbone.     

巴西图巴朗公司烧结机台车加宽技术改造特点

１９９７年９月,奥钢联工程技术公司（ＶＡＩ）为巴西图巴朗黑色冶金公司（ＣＳＴ）完成了一项以提高总产量为目的的烧结及设备改造工程。将烧结机台车的宽度从５．０ｍ增加到５．５ｍ,成为目前世界上最宽的烧结机;完成包括安装先进的监测及工艺控制系统在内的改造措施,烧结总产量大幅度增加。介绍了应用改造方案之后的操作结果及其特点。