Capacitive and solution resistance effects on voltammetric responses of a thin redox layer attached to disk microelectrodes

A rigorous theoretical analysis of cyclic voltammetry of surface-attached redox layers at disk microelectrodes is presented when effects enforced by the solution resistance and the electrode capacitance cannot be neglected. This allows a precise quantitative evaluation of the influence of each of the current components (faradaic, resistive, and capacitive) on the voltammetric shapes through numerical simulation. It is shown that the consideration of the solution resistance and capacitance effects is crucial for the correct treatment of experimental voltammograms at high-voltage scan rates when the resistance is not compensated.     

Acousto-optic interaction in alpha-BaB(2)O(4)and Li(2)B(4)O(7) crystals

Experimental studies and analysis of acousto-optic diffraction in alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are given. Ultrasonic wave velocity, elastic compliance and stiffness coefficients, and piezo-optic and photoelastic coefficients of alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are determined. The acousto-optic figure of merit has been estimated for different possible geometries of acousto-optic interaction. It is shown that the acousto-optic figures of merit for alpha-BaB(2)O(4) crystals reach the value M(2)=(270 +/- 70) x 10(-15) s(3)/kg for the case of interaction with the slowest ultrasonic wave. The directions of propagation and polarization of those acoustic waves are obtained on the basis of construction of acoustic slowness surfaces. The acousto-optic diffraction is experimentally studied for alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals.     

Design of quinonoid-enriched humic materials with enhanced redox properties

The primary goal of this work was to develop quinonoid-enriched humic materials with enhanced redox properties that could be used as potentially effective redox mediators and reducing agents for in situ remediation of soil and aquatic environments. Two different strategies were formulated and tested to derive these materials. The first strategy called for the oxidation of phenolic fragments associated with the humic aromatic core. In a second strategy, polycondensation of these phenolic fragments was carried out with hydroquinone and catechol. The oxidized derivatives and copolymers obtained were characterized using elemental and functional group analyses, and capillary zone electrophoresis. The redox properties were evaluated using ESR spectrometry and reducing capacity determinations. The reducing capacities of copolymers ranged between 1 and 4 mmol/g, which were much higher than the parent material and the oxidized derivatives. Hence, preference should be given to the copolycondensation approach. The quinonoid-enriched humics are nontoxic, water soluble, and resistant to biodegradation; thus, they could be applied as soil amendments to reduce highly mobile oxoanions of heavy metals and radionuclides, or as redox mediators to enhance in situ bioremediation. Otherwise, cross-linked copolymers could be created to serve as inexpensive reductants in permeable reactive barriers designed to remove highly oxidized contaminants from polluted groundwaters.     

Liquid/liquid phase equilibrium in the globulin/salt/water systems. Vicilin

The effect of temperature, salt concentration and dielectric constant of the medium on the liquid/liquid equilibrium in broad bean vicilin/sodium chloride/water and pea vicilin/sodium chloride/water systems was investigated, and the upper critical points were obtained. The critical protein concentration and critical exponents for vicilin-containing systems are compared with those for legumin-containing systems. Phase separation in the vicilin solutions was observed at a lower salt concentration than phase separation in the legumin solutions.     

Mass media campaigns within reach: effective efforts with limited resources in Russia's capital city

Mass media campaigns, while often expensive, are proven, cost-effective interventions and should not be considered out-of-reach, especially where governments have some sway over media markets, where large media discounts are possible or where other novel strategies can be employed.     

A critical review of methods for characterisation of polyphenolic compounds in fruits and vegetables

Phenolic compounds, ubiquitous in plants, are of considerable interest and have received more and more attention in recent years due to their bioactive functions. Polyphenols are amongst the most desirable phytochemicals due to their antioxidant activity. These components are known as secondary plant metabolites and possess also antimicrobial, antiviral and anti-inflammatory properties along with their high antioxidant capacity. Many efforts have been made to provide a highly sensitive and selective analytical method for the determination and characterisation of polyphenols. The aim of this paper is to provide information on the most recent developments in the chemical investigation of polyphenols emphasising the extraction, separation and analysis of these compounds by chromatographic and spectral techniques.     

Companies' opinions and acceptance of global food safety initiative benchmarks after implementation

International attention has been focused on minimizing costs that may unnecessarily raise food prices. One important aspect to consider is the redundant and overlapping costs of food safety audits. The Global Food Safety Initiative (GFSI) has devised benchmarked schemes based on existing international food safety standards for use as a unifying standard accepted by many retailers. The present study was conducted to evaluate the impact of the decision made by Walmart Stores (Bentonville, AR) to require their suppliers to become GFSI compliant. An online survey of 174 retail suppliers was conducted to assess food suppliers' opinions of this requirement and the benefits suppliers realized when they transitioned from their previous food safety systems. The most common reason for becoming GFSI compliant was to meet customers' requirements; thus, supplier implementation of the GFSI standards was not entirely voluntary. Other reasons given for compliance were enhancing food safety and remaining competitive. About 54 % of food processing plants using GFSI benchmarked schemes followed the guidelines of Safe Quality Food 2000 and 37 % followed those of the British Retail Consortium. At the supplier level, 58 % followed Safe Quality Food 2000 and 31 % followed the British Retail Consortium. Respondents reported that the certification process took about 10 months. The most common reason for selecting a certain GFSI benchmarked scheme was because it was widely accepted by customers (retailers). Four other common reasons were (i) the standard has a good reputation in the industry, (ii) the standard was recommended by others, (iii) the standard is most often used in the industry, and (iv) the standard was required by one of their customers. Most suppliers agreed that increased safety of their products was required to comply with GFSI benchmarked schemes. They also agreed that the GFSI required a more carefully documented food safety management system, which often required improved company food safety practices and increased employee training. Adoption of a GFSI benchmarked scheme resulted in fewer audits, i.e., one less per year. An educational opportunity exists to acquaint retailers and suppliers worldwide with the benefits of having an internationally recognized certification program such as that recognized by the GFSI.     

Quality of life in chronic hemodialysis patients in Russia

The aim of this cross-sectional study was to compare health-related quality of life (HRQOL) of Russian hemodialysis (HD) patients with the general population and international data, and to determine factors influencing HRQOL. One thousand forty-seven HD patients from 6 dialysis centers were studied (576 male, age 43.5 +/- 12.5 years, HD duration 55.0 +/- 47.2 months). Health-related quality of life was evaluated by SF-36. Self-appraisal Depression Scale (W. Zung), State-Trait Anxiety Inventory, and Level of Neurotic Asthenia Scale were used. Hemodialysis patients scored significantly lower than the general Russian population in the majority of SF-36 scales. The only exception was the Mental Health score, which was even better than the general population. The Mean physical component score (PCS) of HD patients was 36.9 +/- 9.7, and the mental component score was (MCS) 44.2 +/- 10.5. In multiple linear regression analysis, increasing age, HD duration, depression level and number of days of hospitalization in the past 6 months were significant independent predictors of low PCS along with a low level of serum albumin. Advancing age was also a predictive factor for low MCS along with increase of HD duration, depression level, trait anxiety, and level of asthenia. As far as we know, this is the first study to report on HRQOL of a large sample of Russian HD patients performed using SF-36. Compared with the general population, Russian HD patients had significantly lower scores on the majority of SF-36 scales, especially in the physical domain. The mean PCS and MCS were comparable with European data for HD patients. A number of demographic, clinical, and psychological variables affect HRQOL.