HIV-serostatus disclosure in the context of free antiretroviral therapy and socio-economic dependency: experiences among women living with HIV in Tanzania

The worldwide implementation of free antiretroviral therapy (ART) raised great hopes among policy makers and health organisations about the positive changes it would bring about in attitudes and behaviours towards HIV and AIDS; as well as for infected people's lives. A change in illness perception was anticipated; leading to the hypothesis of a possible change in disclosure rates; patterns and the choice of significant others to inform. In the era of free treatment availability in the United Republic of Tanzania; we examined reasons for disclosure and non-disclosure among HIV-seropositive women enrolled on ART and their choice of significant others to inform. In so doing; we contribute to the necessary yet neglected debate about the social impact of ART on the lives of infected women. The study; for which an ethnographic cross-sectional pilot approach was chosen; was conducted at the Care and Treatment Center (CTC) at Bombo Regional Hospital (BRH) in Tanga city; Tanzania. Data presented here derive from participant observation; questionnaires and semi-structured interviews conducted with 59 HIV-seropositive women on ART. Interestingly; and despite treatment availability; the choice of significant others to inform; as well as reasons for disclosure and non-disclosure; mirror findings from previous studies conducted before the introduction of free ART. The main reason for non-disclosure was fear of discrimination. The hope for social; economic or health support was the main motivation for disclosure; followed by the need for a 'clinic companion' in order to receive ART; as requested by hospital staff. Nevertheless; healthcare staff were not unanimous in thinking that disclosure is always beneficial; thus the recommended extent of disclosure varied. ART and concomitant factors were raised as an entirely new and significant reason for disclosure by interviewees. Finally; findings confirm that despite ART; disclosure remains a highly stressful event for women

Using spin polarised positive muons for studying guest molecule partitioning in soft matter structures.

Fully polarised positive muons substituted for protons in organic free radicals can be used as spin labels which reveal information about the structure, dynamics and environment of these radicals. In applications via the technique of avoided-level-crossing muon spin resonance (ALC-microSR), the positive muon has been used to study the partitioning of phenyl alcohols in lamellar phase colloidal dispersions of a cationic dichain surfactant. Here we describe the experimental technique which permits highly sensitive spectroscopy as previously demonstrated for surfactant mixtures. We also demonstrate its capability in the study of partitioning of cosurfactant molecules in surfactant bilayers in order to elucidate the main factors which contribute to cosurfactant ordering at interfaces. The technique takes advantage of the positive muon combining with an electron to a hydrogen-like atom that is called muonium. This atom attaches to a phenyl group, forming a cyclohexadienyl-type radical that contains the muon as a polarised spin label, providing an excellent probe even for very low phenyl alcohol concentrations. The position of one type of resonance, which on the basis of spectroscopic selection rules is denoted as Delta(0), is related to the solvent polarity of the radicals' environment. The results derived from Delta(0) measurements reveal a systematic trend where the increasing chain length of the phenyl alcohol results in a deeper immersion of the phenyl ring of the alcohol into the surfactant bilayer with the OH group anchored at the interface. In addition, the data suggest partial penetration of water molecules into the bilayer. Furthermore, data ensuing from a second resonance (called Delta(1), which is dependent upon the degree of confinement of the radical within the surfactant aggregate structure) indicates not only that the phenyl alcohol resides in an anisotropic environment, (i.e. that the host molecule is unable to undergo full 3-D reorientation on a timescale of 50 ns), but the resonance line widths indicate that the radicals are undergoing fast rotation about a particular axis, in this instance about the first C-C substituent bond at the phenyl ring. Detailed analysis of these Delta(1) line shapes suggests that other types of motion involving reorientation of the above rotation axis are also present. At room temperature, the hydrocarbon chains of the double layers form an aggregate state commonly referred to as the L(beta) phase, where the motions of surfactant alkyl chains are effectively frozen out. These chains melt on heating over a temperature range which is solution composition dependent (ca. 51 to 67 degrees C), but in all cases leading to a liquid-like disordered hydrocarbon regime whilst retaining the overall lamellar structure (and in this state is termed L(alpha)). Above the L(alpha)/L(beta) chain ordering phase transition the tracer molecules reside within the bilayer, but below this transition (and depending on their water-oil solubility) they are completely or partly expelled. This interpretation is further supported by Heisenberg spin exchange experiments. The water-bilayer partitioning reflects both typical classical and nonclassical hydrophobic solvation depending on temperature and chain length of phenyl alcohols.

A small paramagnetic platinum cluster in an NaY zeolite: characterization and hydrogen adsorption and desorption.

A well-defined cluster containing 12 equivalent platinum atoms was prepared by ion exchange of an NaY zeolite, followed by hydrogen reduction. It was characterized by electron paramagnetic resonance (EPR) spectroscopy, hyperfine sublevel correlation (HYSCORE), and theoretical calculations. Combing the results of the experiments with density functional calculations, the likely structure of this cluster is icosahedral Pt13Hm, possibly with a low positive charge. The adsorbed H/D on the Pt cluster surface can be exchanged reversibly at room temperature. From H/D desorption experiments, an H2 binding energy of 1.36 eV is derived, in reasonable agreement with the calculated value but clearly larger than that for a (111) Pt single-crystal surface, revealing a finite size effect. While the hydrogen-covered cluster should clearly be regarded as a molecule, it is conceivable that the cluster adopts metallic character upon hydrogen desorption. It is likely that up to m=30 H atoms bind to this cluster with 12 surface atoms, which has important implications for the determination of the dispersion of small Pt catalyst particles by hydrogen chemisorption. Calculations as well as experiments give evidence of an interesting magnetic behavior with high-spin states playing a prominent role. There are strong indications that a reservoir of EPR silent but structurally similar clusters exists which can partly be converted to EPR visible species by H/D exchange or by gas adsorption.

Inhalation of U aerosols from UO2 fuel element fabrication.

Publication No. 30 of the International Commission on Radiological Protection (ICRP) assigns the uranium oxides UO2 and U3O8 to transportability class Y, i.e. the half-life of these compounds in the lungs is about 500 days. This assignment seemed not to be in accordance with our experience resulting from incorporation surveillance during UO2 fuel element fabrication. Persons who worked in atmospheres containing UO2 aerosols with activity concentrations significantly above the derived air concentrations (DAC) for class Y U showed much lower activity in the lungs than would be expected according to the ICRP. To understand this discrepancy, aerosol concentrations and aerosol particle-size distributions at work places with the possibility of UO2 incorporation, the activity of urine and feces and the lung activity of persons working at these places were measured in an investigation program. The results are only consistent with the ICRP lung model if one uses a measured biological half-life in the lungs of 109 days and a measured AMAD of 8.2 micron instead of the ICRP standard assumptions of 500 days and 1.0 micron, respectively. ICRP Publication No. 30 recommends application of specific parameters for health physics instead of standard model values. For the special conditions in our UO2 fuel fabrication plant we therefore derive limits of air concentrations, lung activities and fecal and urinary activity concentrations by applying our measured particle-size and lung-retention parameters to the ICRP model. Our special derived limits in comparison to class Y limits for U after ICRP Publication No. 30 for a 1-micron AMAD and 500-day half-life (in brackets) are: (a) annual limit of intake: 6 X 10(4) Bq/y (1 X 10(3) Bq/y); (b) derived air concentration: 20 Bq/m3 (0.6 Bq/m3); (c) derived lung activity: 1.6 X 10(3) Bq; (d) derived fecal activity: 14 Bq/day; and (e) derived urine activity: 8.9 Bq/day. The committed dose equivalents calculated from our measured data and from our modified derived limits proved consistent for the different incorporation control methods (determination of air concentration, lung, fecal or urinary activity). The authors recommend that in accordance with ICRP Publication No. 30, the national rules and regulations on activity incorporation provide the possibility to derive special limits from specific work-place parameters such as particle-size distributions and biological half-lives, thus supplementing the ICRP standard assumptions of 1 micron AMAD and biological half-lives of 0.5 days for class D, 50 days for class W and 500 days for class Y compounds.