Localization and quantification of carbon-centered radicals on any amino acid of a protein

A general strategy to localize and quantify carbon-centered radicals within proteins is described. The methodology was first exemplified on amino acids and then on a peptide. This method is applicable to any protein system regardless of size, and the site of hydrogen abstraction by *OH on all residues within proteins is easily and accurately detected.     

A project evaluation system in the state economic information system of China An operations research practice in public sectors

Operations Research (OR) methodology and its mathematical models have been widely accepted as management means in China, not only in industry and agriculture, but also in non-profit organizations, including the governmental departments and institutions. In this paper, we introduce an OR practice in the State Information Center (SIC) of China. The task is to design and develop a system, the Project Evaluation System, for SIC to manage investments in the various parts of the State Economic Information System of China (SEIS). It is a decision support system with various OR models and algorithms combined together as the core part of the system. Data Envelopment Analysis is used to evaluate the relative efficiencies of the sub-systems of the SEIS and the Analytic Hierarchy Process methodology is adopted to form the decision process. To allocate further investment to the sub-systems, an investment prediction model for non-profit organizations was formulated which is in a format of a parametric linear programming problem. This new OR model can be applied in many decision problems in economy and finance. We also discuss in this paper the experience summed up from our practice.     

Dietary exposure to pesticide residues in Yaoundé: the Cameroonian total diet study

Dietary exposure to pesticide residues was assessed in Yaoundé, Cameroon, using the total diet study (TDS) method. Sixty-three composite samples, representative of the foods as consumed in Yaoundé, were collected, prepared, and analysed for residues of pesticides including organochlorine, organophosphorous, and pyrethroids. A multi-residue method was used with a limit of detection (LOD) of 0.005 mg kg(-1). Additional analyses were performed for dithiocarbamates (LOD=0.050 mg kg(-1)), glyphosate (LOD=0.005 mg kg(-1)) and chlordecone (LOD=0.0008 mg kg(-1)) on certain composites samples. The overall contamination was low with 37 out of 46 pesticides below the LOD in all samples. The estimated upper bound (for values less than the LOD equal the LOD; and values less than the LOQ equal the LOQ) of the mean dietary exposures ranged from 0.24% (cypermethrin) to 3.03% (pirimiphos-methyl) of the acceptable daily intakes (ADIs) for pesticides for which at least one analysis was greater than the LOD. This study suggests a low dietary exposure to pesticide residues in Yaoundé.     

Porous Si/Cu6Sn5/C composite containing native oxides as anode material for lithium-ion batteries

Journal of Materials Science: Materials in Electronics - Porous Si/Cu6Sn5/C composite containing native oxides was prepared via solid-state mechanical milling and wet chemical etching. This...     

Microwave based nanogenerator using the ratchet effect in Si/SiGe heterostructures

Ratchet based microwave current generators and detectors were developed in Si/SiGe heterostructures for wireless communication with the possibility of extending the detection limit to the terahertz range. A microwave induced ratchet current was generated in the two-dimensional electron gas by patterning an array of semicircular antidots in hexagonal geometry. The spatial asymmetry created by the semicircular antidots forces the electrons under the influence of the microwave electric field to move preferentially towards the direction of the semidisc axis. A photovoltage of the order of few millivolts was observed. Such a photovoltage was completely absent in a symmetric system consisting of circular antidots. The induced photovoltage increased monotonically with microwave power and was found to be independent of the microwave polarization. This device opens the possibility of employing silicon based heterostructures for nanogenerators and other wireless communication devices using microwaves.     

Use of global sensitivity analysis in quantitative microbial risk assessment: application to the evaluation of a biological time temperature integrator as a quality and safety indicator for cold smoked salmon

The aim of this study was to apply a global sensitivity analysis (SA) method in model simplification and to evaluate (eO)^®, a biological Time Temperature Integrator (TTI) as a quality and safety indicator for cold smoked salmon (CSS). Models were thus developed to predict the evolutions of Listeria monocytogenes and the indigenous food flora in CSS and to predict TTIs endpoint. A global SA was then applied on the three models to identify the less important factors and simplify the models accordingly. Results showed that the subset of the most important factors of the three models was mainly composed of the durations and temperatures of two chill chain links, out of the control of the manufacturers: the domestic refrigerator and the retail/cabinet links. Then, the simplified versions of the three models were run with 10⁴ time temperature profiles representing the variability associated to the microbial behavior, to the TTIs evolution and to the French chill chain characteristics. The results were used to assess the distributions of the microbial contaminations obtained at the TTI endpoint and at the end of the simulated profiles and proved that, in the case of poor storage conditions, the TTI use could reduce the number of unacceptable foods by 50%.     

Kinetics of reactions in CH4\N2 afterglow plasma : a simplified model

Processes in CH₄\N₂ microwave plasma are studied by computer experiment based on experimental data derived from the nitrogen flowing afterglow discharge. By means of a macroscopic kinetic approach, the original model consisting of 72 chemical reactions between 35 active species in the discharge is analysed in detail, the main attention being devoted both to the initial stages of methane decomposition and to the yield of stable products together with the most important reactions for the production of individual species. From these reactions the new simplified model is formulated.     

Electrowinning of palladium using a modified cyclone reactor

The electrochemical behaviour of palladium in dilute acidic chloride solution was investigated using a rotating disc electrode system and the electrowinning of palladium using a modified electrochemical cyclone cell was also carried out. The effect of several variables such as applied voltage, hydrochloric acid concentration and electrolyte flow rate were studied to obtain the optimum conditions for electrowinning. More than 99% of the palladium in solution was recovered within an hour under the optimum conditions using the cyclone cell and grey powdery deposits were observed at a high applied voltage. The purity of palladium electrowon from the leach liquor was at least 99%.