Solution properties of polyelectrolytes. II. Comparison of the effects of both polyion and eluent salt concentrations on the calibrations in aqueous exclusion chromatography

The elution behaviour of charged water-soluble polymers (sodium polystyrene sulphonate) in both salt-free and NaCl-containing aqueous mobile phases has been investigated by size-exclusion chromatography. A comparative analysis has been established between the results as a function of polyion and salt concentrations, which demonstrates that the chromatographic behaviour is similar in both cases. The variation of the slopes of the different concentration-dependent calibration curves is discussed in terms of polyelectrolyte conformational changes. Finally, a semi-empirical model has been developed to predict the dependence of the elution volume in either polyion or salt concentration, and its validity has been checked in a range from very dilute to moderate concentrations.     

EBOFERA: A companion for FERA ADCs

A data transfer problem using FERA modules was found in a heavy ion nuclear physics experiment. The source of the problem was spotted in the handling of some signals on the FERA control bus. A modification of this handling is proposed and performed by means of a new CAMAC-FERA control module, the EBOFERA. Furthermore, this module has a number of useful features like the master gate and clear signals handling, event tagging, pattern unit and event counter.     

Heterogeneity among neuroepithelial cells in the chick retina revealed by immunostaining with monoclonal antibody PM1

Endothelin (ET) 1 is a powerful vasoconstrictor of coronary arteries and may play a role in coronary spasm, atherosclerosis, and myocardial infarction. Previous studies have demonstrated that intracoronary ET caused marked vasoconstriction of the coronary circulation; however, it remains unclear which ET receptor types are present and which of these receptors mediate this vasoconstriction. To characterize the ET receptors present in dog coronary arteries, competition binding assays with radiolabeled ET-1 using ET-1, ET-3, ETA receptor antagonist BQ-123, and sarafotoxin S6c were performed. Three binding sites were apparent in the left circumflex coronary artery: an ETA receptor, a high-affinity ETB receptor, and a lower-affinity ETB receptor. To investigate the in vivo effects of ETB receptor stimulation, intracoronary sarafotoxin S6c, a highly selective ETB agonist, was administered in anesthetized open-chest dogs in a constant-pressure coronary artery perfusion model. Sarafotoxin S6c doses of 0.1 and 0.3 microgram caused a transient pronounced decrease in coronary resistance. Doses of 1.0 and 3.0 micrograms caused marked decreases in coronary diameter and blood flow, as well as myocardial segmental shortening. These effects of sarafotoxin S6c were not inhibited by constant infusion of BQ-123. The present study demonstrates the presence of ETB receptors in the canine coronary circulation that can mediate both vasodilation and vasoconstriction. These findings have important implications for an understanding of the pathophysiological function of ET in the coronary vasculature and for the development of therapeutically effective ET antagonists.     

Microbiology of Borrelia burgdorferi

The acute (single bout of exercise) and chronic (exercise training) effects of exercise on plasma leptin were investigated in 97 sedentary adult men (n = 51) and women (n = 46) participating in the HERITAGE Family Study. Exercise training consisted of a standardized 20-wk endurance training program performed in the laboratory on a computer-controlled cycle ergometer. Maximal oxygen uptake, body composition assessed by hydrostatic weighing, and fasting insulin level were also measured before and after training. Pre- and posttraining blood samples were obtained before and after completion of a maximal exercise test on the cycle ergometer. Exercise training resulted in significant changes in maximal oxygen uptake (increase in both genders) and body composition (reduction of fat mass in men and increase in fat-free mass in women). There were considerable interindividual differences in the leptin response to acute and chronic effects of exercise, some individuals showing either increase or reduction in leptin, others showing almost no change. On average, leptin levels were not acutely affected by exercise. After endurance training was completed, leptin levels decreased significantly in men (from 4.6 to 3.9 ng/ml; P = 0.004) but not in women. However, after the training-induced changes in body fat mass were accounted for, the effects of exercise training were no longer significant. Most of the variation observed in leptin levels after acute exercise or endurance training appears to be within the confidence intervals of the leptin assay. We conclude that there are no meaningful acute or chronic effects of exercise, independent of the amount of body fat, on leptin levels in humans.     

Postnecking elastoplastic characterization: Degree of approximation in the bridgman method and properties of the flow-stress/true-stress ratio

The stress and strain radial distributions within the minimum cross section of a tensile specimen undergoing necking, calculated with the Bridgman method, differ, in some cases substantially, from finite-element method (FEM) results. Analyses of the possible reasons for these differences show that an important role is played by the uniformity of the strain distribution assumed by Bridgman. In this study, three types of steels were subjected to tensile testing, and FEM analyses were performed to simulate the experimental trails. The comparison of the experimental and numerical results indicates the magnitude of the approximations intrinsic to the Bridgman method. Through further FEM analyses, it was possible to isolate, in qualitative terms, the influence of the Bridgman approximation from that of the void growth. This has been made by applying the Bridgman formulation to the proper FEM output data and comparing the resulting curves to the curves used as material input for the same analyses. Finally, it was found that, over a certain range of hardening materials, the correction of the true curve depends only on the necking strain, within the same error level given by the Bridgman method. This means that, once the corrective law common to many materials is found, then the correction procedure is substantially improved in terms of effort and time consumption, because it does not need the necking-curvature measurements required by the Bridgman method.     

Occurrence of ochratoxin A in wine and grape juice marketed in Rio de Janeiro, Brazil.

Ochratoxin A (OA) is receiving attention world-wide because of the hazard it poses to human health. The aim was to test the distribution of OA in grape juice, pulps of frozen grapes, and national and imported table wine obtained from markets in Rio de Janeiro, Brazil. Analytical methodology using immunoaffinity column for OA extraction and clean-up with a final separation on a reversed-phase (C(18)) column and fluorescence detection in high-performance liquid chromatography showed a detection limit of 21 ng l(-1). The mean recovery was 91% for red wines and 82% for white wines; while the mean recoveries for juices and pulps of frozen grapes were 91.6 and 88%, respectively. Of 64 samples of grape juice and frozen pulps, 25% were positive for OA, being the mean content of 37 ng l(-1) with a maximum concentration of 100 ng l(-1). In wines, the mean concentration detected in 80 samples analysed was 34.4 ng l(-1) with 28.75% of positive samples. Red wines showed the highest percentages and levels of contaminated samples: 38% and 37 ng l(-1), respectively. The white wine contained levels above 26 ng l(-1) in 17.75% of the analysed samples. The levels of contamination detected in red wine sold in Río de Janeiro were not enough to surpass the virtually safe dose established as 5 n g kg(-1) body weight of daily intake.     

Complex dynamics through fuzzy chains

This paper gives a new contribution to characterize a class of complex systems build as arrays of coupled fuzzy logic based chaotic oscillators and investigates their dynamical features. Different spatio-temporal dynamics have been reproduced using interconnected fuzzy chaotic cells in order to study the effects, due to the variation of some parameters and network topologies, in the collective behavior and to highlight the synchronization capability of the complex fuzzy systems under consideration. The synchronization characteristics have been focused by defining a behavioral index.     

Short stature and azoospermia in a patient with Y chromosome long arm deletion

We report on a 42-year old male with short stature, azoospermia and a wide deletion of long arm of Y chromosome. On physical examination, the patient showed height of 149 cm (< 1 degree centile) and reduced volume (3 ml) and consistency of the testes. On hormonal evaluation, he showed increased serum gonadotropins and normal serum testosterone levels though its HCG stimulated levels were limited. Serum thyroid hormones were normal. Serum GH levels in baseline evaluation as well as after GHRH and GHRH + pyridostigmine administration were normal. Serum IGF I levels were lower than normal in baseline evaluation whereas its response to the GH administration was in the normal range. The bilateral testicular biopsy showed tubular atrophy, hyalinosis, interstitial sclerosis and a histological picture of a Sertoli cell only syndrome. Moreover the patient showed arthropathy, otopathy, small chin, small mouth and truncal obesity. On genetic evaluation, the patient showed a 46,X,delY (pter--q11.1:) karyotype and loss of several DNA loci on Yq. In fact he preserved short arm SRY, centromeric DYZ3 and more proximal euchromatic region Yq loci, including DYS270, DYS271, DYS272, DYS11, DYS273, DYS274, DYS148, DYS275, and missed more distal DNA loci from DYS246 to DYZ2. These results disclosed a wide Y long arm deletion, including all hypothized Yq azoospermia loci (except for AZFa and probably for one of the RBM genes, which lie proximally to the deletion) and possibly the Y-specific growth control region (GCY), mapped between DYS11 and DYS246 loci. This deletion is responsible for the complete azoospermia of the patient and probably also for his short stature, even if other factors could be implicated in the statural impairment. It further possibly allowed to relate the GCY gene(s) to the control of GH or IGF-I receptor or post-receptor pathway, being the alteration of this gene(s) consistent with the hormonal pattern of the patient.     

CESA-1 thermal storage system evaluation

An evaluation follows of the CESA-1 solar thermal storage based on an eutectic mixture of 53% KNO₃, 39% NaNO₂, and 8% NaNO₃ molten salt, existing on the Plataforma Solar de Almería. Main parameters of the charge/discharge cycles (inlet/outlet temperatures, mass flows, and charge/discharge rates) were varied to simulate different solar multiples.The net thermal-to-thermal efficiency of this system was determined to be 72%, once the energy requirements to drive it are discounted. Thermal loss coefficients of both tanks were measured and found to be 0.327 and 0.265 W/m² K for the hot and cold tank, respectively.     

Dynamic insulation in transmission-line design

The evolution of the dynamic insulation concept from the integration of two existing technologies is presented. Separate solutions proposed in the recent literature for the reduction of voltage stresses due to nonuniform electric fields and to transient overvoltages in EHV and UHV transmission line insulation are discussed and then integrated into one. The resulting combination, i.e. dynamic insulation, has the potential of providing a superior alternative for the abatement of these two problems and others. Dynamic insulation is a new concept which provides a systems approach to the electrical and mechanical design for tranmission-like insulation. Because of its multifunction capability, dynamic insulation offers various technical and economical advantages, including the mitigation of the effects of contamination on insulation and also the control of fault initiation overvoltages as indicated by transmission-like simulations. Further theoretical studies and experimental work applying known technology is suggested to verify the ideas proposed.