Styrene copolymers as pollutant adsorbents : Safe sampling volume determination

The determination of safe sampling volumes of benzene and acetone on air samplers filled with Porapak Q, Chromosorb 101, 102 and 103 is described. Two direct methods are employed; one method is based on frontal chromatography, while the second one is a concentration method followed by thermal desorption. The results are compared to those determined by the indirect pulse chromatographic method. The safe sampling volumes determined by the direct methods were in accordance. The indirect method gives slightly different values; however, this procedure is carried out at "infinite dilution". The effect of the pollutant concentration on the safe sampling volumes was also examined. The values decrease with increasing pollutant concentration.     

Therapeutic Potential of Highly Selective A3 Adenosine Receptor Ligands in the Central and Peripheral Nervous System

Ligands of the G_i protein-coupled adenosine A₃ receptor (A₃R) are receiving increasing interest as attractive therapeutic tools for the treatment of a number of pathological conditions of the central and peripheral nervous systems (CNS and PNS, respectively). Their safe pharmacological profiles emerging from clinical trials on different pathologies (e.g., rheumatoid arthritis, psoriasis and fatty liver diseases) confer a realistic translational potential to these compounds, thus encouraging the investigation of highly selective agonists and antagonists of A₃R. The present review summarizes information on the effect of latest-generation A₃R ligands, not yet available in commerce, obtained by using different in vitro and in vivo models of various PNS- or CNS-related disorders. This review places particular focus on brain ischemia insults and colitis, where the prototypical A₃R agonist, Cl-IB-MECA, and antagonist, MRS1523, have been used in research studies as reference compounds to explore the effects of latest-generation ligands on this receptor. The advantages and weaknesses of these compounds in terms of therapeutic potential are discussed.     

Analysis of complex mixtures by capillary gas chromatography with statistical estimation of the number of components

Evaluation of the number of components by the Davis-Giddings single chromatogram method is applied to capillary gas chromatograms of a dichloromethane extract of camomile. Various runs with OV-1 or Carbowax 20M as the stationary phase were done under different experimental conditions (column temperature programming rate and column length). The results showed that the number of components obtained by this statistical procedure does not depend greatly on the nature of the stationary phase or on the experimental conditions. The component number of the camomile extract was about 200 and the stand-alone probability at unit resolution was 0.2–0.3.     

Magnetic reconnection in collisionless plasmas

A class of processes involving magnetic field reconnection, in collisionless plasmas and magnetic configurations where the field undergoes a finite change of direction, is investigated. Reconnecting modes that rely on the effects of electron Landau resonance and density gradient for their excitation are found to require the analytical or numerical treatment of four consecutive asymptotic regions. The influence of finite electron temperature gradient in the region where the effects of electron Landau resonance prevail, and the convection of energy toward the region where ion Landau resonance is dominant tend to dampen these modes. Conversely, significant distortions of the ion distribution can follow their excitation. The relevance of the obtained results to experimental observations on laboratory plasmas and in space physics is discussed. Different processes are involved with magnetic reconnection in magnetic configurations where the field does not have appreciable shear but has a neutral surface on which it vanishes.