A new biosynthetic tracer for the inline measurement of virus retention in membrane processes: part I--Synthesis protocol.

In this study, a new biosynthetic tracer was developed to characterize the virus retention dynamics of membrane systems. This new tracer is a modified bacteriophage obtained by the grafting of enzymatic probes to an MS2 bacteriophage, one of the smallest non-pathogenic bacteria viruses, with an average diameter of about 30 nm. A protocol for the synthesis and purification of this new tracer was developed in this work. The production of this biosynthetic tracer was first qualitatively shown by a chromatographic characterization and an enzymatic test. The average number of probes grafted per phage was then quantified for three batches of tracers made from the same native phage suspension and the same batch of enzymatic probes. This quantification demonstrated the reproducibility of the synthesis protocol developed.

A new biosynthetic tracer for the inline measurement of virus retention in membrane processes: part II. Biochemical and physicochemical characterizations of the new tracer.

In a previous work, a reproducible procedure to produce a new biosynthetic tracer was developed. This new tracer is an MS2 bacteriophage with enzymatic probes grafted on its surface, which can induce enzymatic activity of the tracer. In this paper, the biochemical and physicochemical characteristics of this new tracer are determined. A protocol was developed to determine the specific enzymatic activity kcat(TRACER) of the tracer, which was found to be 2.93±0.78×10(4) min(-1) on average. Physicochemical characterizations of this new tracer showed that it is representative of viruses and may thus be used as a virus surrogate to assess the virus retention of membrane systems inline. Notably, the mean diameter and molecular weight of the tracer were found to be respectively 64.1±0.3 nm and 12,140±3654 kDa, which are within the size and molecular weight ranges of pathogenic viruses carried by water. The tracer surface was also studied and revealed the considerable porosity of the grafted probe layer, with a mean porosity of 88%, which could explain why the zeta potential of the tracers (-14.34±1.66 mV) was nearly the same as that of the native MS2 phages. Finally, a comparison between filtration of the reference microorganism used for membrane performance assessment (the MS2 phage) and the tracer suspensions showed the same filtration behaviour.

Taking mass transfer limitation into account during ozonation of pollutants reacting fairly quickly.

Various situations observed when oxidizing organic compounds via ozone in a semi-batch reactor are illustrated. The resistance to the transfer of ozone from gas to liquid is accounted for using the film model. The mass balances are numerically solved simultaneously within the reactor and within the film to produce time dependent profiles of concentrations, Hatta, enhancement and depletion factors. Firstly, theoretical profiles are exemplified for various kinetic regimes from slow to fast; reaction occurs either in the bulk, in the film or in both. This shows the drastic importance of the shapes of the gas concentration profiles both at the exit of the reactor and in the liquid phase - in determining the regime. Then, a typical example dealing with fumaric acid ozonation is shown. Firstly, the acid itself oxidizes rapidly producing an intermediate regime: part of the reaction occurs within the film, part within the bulk and the rate constant can be determined. Then, the by-products oxidize more slowly producing a typical regime: reaction occurs within the bulk, the concentration of dissolved ozone is almost 0 and the mass transfer coefficient can be determined. Finally, when all organics have oxidized, the self-decomposition of ozone governs a slow kinetic regime: the concentration of dissolved ozone is close to equilibrium.

Pulmonary manifestations in HIV seropositivity and malnutrition in Zimbabwe.

Over a 10 month period 184 children, aged 5 years or less, who died at home had their nutritional status and HIV serostatus established; necropsies were also carried out. The HIV antibody test was positive in 122/184 (66%). Of the HIV seropositive children Pneumocystis carinii pneumonia was present in 19 (16%), cytomegalovirus pneumonia in nine (7%), and lymphoid interstitial pneumonitis in 11 (9%). Opportunistic infection was therefore seen in 28/122 (23%) of the seropositive cases but in none of the seronegative cases. Tuberculosis was present in 8/184 (4%): 6/122 (5%) in HIV seropositive and 2/62 (3%) in seronegative children. Lung aspirate showed positive bacterial isolates in 106/ 122 (86%) of HIV seropositive and 46/62 (74%) of seronegative children with Gram negative organisms predominating in both groups. Malnutrition was common and affected 106/184 (58%); positive growth was obtained in 98 (92%) of the malnourished children irrespective of their HIV serostatus. Malnutrition was significantly associated with bacterial lung infection after adjustment for the confounding effect of HIV status. No association was found between HIV serostatus and bacterial lung infection that could not be attributed to malnutrition at the time of death. The importance of adequate nutrition in reducing the risk of bacterial infection in HIV infected children is apparent.

Interpleural local anaesthesia: anatomical basis for mechanism of action.

India ink was injected through an extradural catheter placed in the right interpleural space in cadavers at autopsy. The lung was removed and the spread of the ink noted and photographed. In six cadavers, block sections were cut at the anterior axillary line through three ribs, intercostal muscles and parietal pleura. The blocks were fixed in formalin and then decalcified, sectioned, stained and mounted on slides. In all cases the ink covered the chest wall, lung and diaphragm, and was seen to pool in the paravertebral area. Examination of the histological slides revealed black pigment on the pleural surface and in the subpleural space. The mechanism of transport across the parietal pleura is discussed.

Nutritional status of an urban community in Zimbabwe.

PIP: The rural population of many developing countries show an association between poor health and malnutrition, but little information is available on the urban communities. To investigate nutritional status there, the researchers chose Luveve, a black township of Zimbabwe. The heads of the household from each of 70 blocks were interviewed and the circumference of their families' mid upper arms were measured. Of the households visited, incomes ranged from US$30 to $300 per month. Food supplies were purchased from a grocer; the majority also maintained a vegetable garden. Diets were found to consist primarily of refined cereals, vegetables, soft drinks, and some milk and eggs. As regards infant feeding, the 66 mothers interviewed reported weaning their babies from the breast by 5 months. On the basis of arm circumference measurements, the population was not found to be undernourished. In fact, gross obesity was observed in 50% of the adults and many preschool children. Subnutrition was reported in only 3 members of the community. These measures vary considerably from those of the rural populations. The most significant finding was widespread obesity probably due to the high consumption of refined, starchy products. This could translate into obesity related diseases such as hypertension, diabetes, and cardiovascular disease.^ieng