Physicochemical and microbiological characteristics of biltong,a traditional salted dried meat of South Africa

The microbiological and physicochemical characteristics of several commercial beef, kudu and springbok biltong samples from South Africa were assessed in this study. Analysis of samples allowed their differentiation into ‘dry’ and ‘moist’ samples. Dry biltong showed low moisture content (21.5–25.3 g/100 g), a low water activity (0.65–0.68) and a high salt content (5.5–7.9 g/100 g), while moist biltong showed a higher moisture content (35.1–42.8 g/100 g), a higher water activity (0.85 to 0.89) and a lower salt content (3.8–5.6 g/100 g). The pH value did not vary significantly between both groups (5.00–6.26). The results showed that dry biltong presented a low total plate count (TPC) content, a high level of lactic acid bacteria (LAB) and a high level of d-lactic acid as compared to moist biltong. These results suggest that dry biltong complies with the standard hygienic quality (TPC < 7 log cfu/g in agreement with the Food Standards Agency), while moist biltong samples generally showed a low content of d-lactic acid and a low ratio LAB/TPC.     

A novel multi-walled carbon nanotube modified sensor for the selective determination of epinephrine in smokers

Epinephrine (EP), an important neurotransmitter, energizes and speeds up the various body systems and plays an important role during the time of stress and low blood sugar level. There is a close relation between the release of epinephrine and smoking. Edge plane pyrolytic graphite electrode modified with multi-walled carbon nanotubes (MWNTs/EPPGE) has been used as a sensor for the efficient quantitative determination of epinephrine in body fluids of smokers and nonsmokers in resting stage at physiological pH 7.2 by using cyclic voltammetry (CV) and square wave voltammetry (SWV). The oxidation of epinephrine occurred in a well-defined peak having peak potential (E_p) ∼150 mV at pH 7.2. The limit of detection (3σ/slope) and limit of quantification were found to be 0.15 × 10⁻⁹ and 0.48 × 10⁻⁹ M using proposed sensor, respectively. The modified electrode was also utilized for the analysis of commercial sample of epinephrine in order to examine the accuracy of the proposed method. The analytical performance of the modified electrode has been evaluated for quantification of EP in real samples even in the presence of common coexisting biomolecules such as uric acid, ascorbic acid, dopamine and norepinephrine. The voltammetric response of the developed nanosensor towards epinephrine determination in body fluids is fast, sensitive and selective having desirable reproducibility and stability. A comparison of results with high performance liquid chromatography (HPLC) shows a good agreement.     

A symmetric finite element formulation for the inverse problem of aquifer transmissivity

This paper presents a symmetric isoparametric finite element formulation for the inverse problem of aquifer transmissivity calculation with known piezometric head. An important aspect of the present formulation is that the groundwater flow equation describing the aquifer behavior is transformed into a second-order differential equation by introducing an artificial variable φ. The two-dimensional, line and transition elements derived based on the weak formulation of this transformed equation possess symmetric matrices. In the formulation of the line elements φ and its derivative in η direction are retained as primary variables. This permits modelling of sudden changes in aquifer width. The transition elements provide a natural connecting link between the two-dimensional elements and the line elements. The line elements provide an efficient means of modelling aquifers with unidirectional flow. Numerical examples are given. A comparison of the results obtained here with the Galerkin finite element solution (nonsymmetric formulation) clearly demonstrates the superiority of the formulation presented here.     

Cognitive function in children who receive organ transplantation.

The number of children who undergo cardiac, renal, and liver transplantation continues to increase. This review of the literature describing their cognitive function indicates that deficits ranging from gross IQ delay to subtle neuropsychological dysfunction are present in some of these children both before and after transplantation. However, with the exception of certain definite contributors to vulnerability, such as cyanotic heart disease, early onset of disease, and growth deficits in infancy (particularly in head circumference and height), the correlates of cognitive deficits are not clear. Problems with determining contributing variables include significant heterogeneity within study populations, difficulties obtaining appropriate control groups, and the need for longitudinal, long-term studies. Additional research is required to address limitations of past studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Use of Interval Analysis in Hydrologic Systems

Hydrological data are often highly inaccurate. Interval methods help to estimate inaccuracy caused by data uncertainty, both for forward problems (in which we predict how water will flow in the known medium), and for the inverse problems (in which we observe how water flows and determine the properties of the medium).     

Melting behavior and surface morphology of poly(vinyl acetate‐co‐vinyl alcohol) copolymer

In a study of the surface morphology of commercial poly(vinyl acetate‐co‐vinyl alcohol) (ACA copolymer) with different percents of hydrolysis, different structures like fibrils, spherulites, micelles, vesicles, and spheroids were seen. The copolymer was crystallized by annealing at two different temperatures. The morphology of the polymer after crystallization and also without crystallization was studied. A decrease in the melting temperature just by heating to the melting temperature was observed, and for a detailed study, repetitive heating of the copolymer was carried out and changes in the mass and heat of fusion after every heating was recorded. The morphology of the copolymer after repetitive heating was studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1211–1218, 2002     

Theoretical Study of Specific Heat,Density of States,Free Energy,and Critical Field of High Temperature Cuprate Superconductors Based on Intra and Interlayer Interactions

The role of attractive interlayer and intralayer interactions in layered high T _c cuprate superconductors have been investigated using a one-band two layer tight binding Hamiltonian. Self-consistent equations for the superconducting order parameter (Δ) and critical temperature (T _c ) are derived using double time Green’s functions and equation of motion method. The expression for excitonic type correlation (γ _c ), specific heat, density of states, free energy, and critical field are obtained. The interlayer interactions play an important role in the enhancement of T _c in layered high T _c cuprates. The oxygen isotope effect is also analyzed. The agreement between theoretical and experimental results for the system YBa_2−x La _x Cu₃O₇ (0≤x≤0.5) is quite satisfactory.      

Voltammetric determination of bisoprolol fumarate in pharmaceutical formulations and urine using single-wall carbon nanotubes modified glassy carbon electrode

The electrochemistry of bisoprolol fumarate (BF) has been investigated by differential pulse voltammetry at a single-wall carbon nanotubes (SWNTs) modified glassy carbon electrode (GCE). The prepared electrode showed an excellent electrocatalytic activity towards the oxidation of BF leading to a marked improvement in sensitivity as compared to bare glassy carbon electrode where electrochemical activity for the analyte cannot be observed. The SWNTs-modified GCE exhibited a sharp anodic peak at a potential of ∼950 mV for the oxidation of BF. Under optimum conditions linear calibration curve was obtained over the BF concentration range 0.01-0.1 mM in 0.5 M phosphate buffer solution (pH 7.2) with a correlation coefficient of 0.9789 and detection limit of 8.27 × 10⁻⁷ M. The modified electrode has been applied for the drug determination in human urine with no prior extraction and in commercial tablets. The proposed method has also been validated.     

Influence of nanoparticles on glass transition of polymers

Tunability of glass transition temperature of poly-methylmethacrylate has been achieved using homogeneously dispersed gold nanoparticles of different weight fraction within the polymer matrix. Remarkably, depression in glass transition temperature with respect to the neat polymer was observed for poly-methylmethacrylate (120 K and 15 K) by varying the weight fraction of the gold nanoparticles contrary to the conventional results in literature which shows elevation in Tg for attractive polymer-particle interaction, as is the case here. The magnitude of the shift in glass transition temperature is large for the higher of the two molecular weight of poly-methylmethacrylate studied here. Possible explanations of the observed behavior are provided, although more experiments are underway to unravel the intricacies of the observed phenomena.     

Self-Assembled,Chitosan Grafted PLGA Nanoparticles for Intranasal Delivery: Design,Development and Ex Vivo Characterization

The objective of present study was to modify the surface of Poly(D,L-lactide-co-glycolide acid) (PLGA) nanoparticles (NPs) with chitosan to enhance the mucoadhesive potential of carrier system. Grafting of chitosan on PLGA surface was carried out via amide bond formation mediated by carbodiimide and confirmed by FTIR spectroscopy. Self-assembled PLGA NPs containing chlorpromazine hydrochloride were fabricated by 2³ factorial design. The improved mucoadhesive potential was confirmed by several tests including in vitro mucoadhesion study. Ex vivo permeation was satisfactory. Histopathological study on sheep nasal mucosa revealed safe mucoadhesion. They were also found to be robust on accelerated stability study.