93 research outputs found
Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique
Pregnancy outcomes and cytomegalovirus DNAaemia in HIV infected pregnant women with CMV
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Rate , correlates and outcomes of repeat pregnancy in HIV-infected women
Objectives: The aim of the study was to assess the rate, determinants, and outcomes of repeat pregnancies in women with HIV infection. Methods: Data from a national study of pregnant women with HIV infection were used. Main outcomes were preterm delivery, low birth weight, CD4 cell count and HIV plasma viral load. Results: The rate of repeat pregnancy among 3007 women was 16.2%. Women with a repeat pregnancy were on average younger than those with a single pregnancy (median age 30 vs. 33 years, respectively), more recently diagnosed with HIV infection (median time since diagnosis 25 vs. 51 months, respectively), and more frequently of foreign origin [odds ratio (OR) 1.36; 95% confidence interval (CI) 1.10–1.68], diagnosed with HIV infection in the current pregnancy (OR: 1.69; 95% CI: 1.35–2.11), and at their first pregnancy (OR: 1.33; 95% CI: 1.06–1.66). In women with sequential pregnancies, compared with the first pregnancy, several outcomes showed a significant improvement in the second pregnancy, with a higher rate of antiretroviral treatment at conception (39.0 vs. 65.4%, respectively), better median maternal weight at the start of pregnancy (60 vs. 61 kg, respectively), a higher rate of end-of-pregnancy undetectable HIV RNA (60.7 vs. 71.6%, respectively), a higher median birth weight (2815 vs. 2885 g, respectively), lower rates of preterm delivery (23.0 vs. 17.7%, respectively) and of low birth weight (23.4 vs. 15.4%, respectively), and a higher median CD4 cell count (+47 cells/μL), with almost no clinical progression to Centers for Disease Control and Prevention stage C (CDC-C) HIV disease (0.3%). The second pregnancy was significantly more likely to end in voluntary termination than the first pregnancy (11.4 vs. 6.1%, respectively). Conclusions: Younger and foreign women were more likely to have a repeat pregnancy; in women with sequential pregnancies, the second pregnancy was characterized by a significant improvement in several outcomes, suggesting that women with HIV infection who desire multiple children may proceed safely and confidently with subsequent pregnancies
Good prenatal detection rate of major birth defects in HIV-infected pregnant women in Italy
What's already known about this topic? Exposure to antiretroviral treatment in pregnancy does not seem to increase the risk of birth defects, but there is no information on the rate of prenatal detection of such defects. What does this study adds? We provide for the first time, in a national case series, information about prenatal detection rate in women with HIV (51.6% for any major defect, 66.7% for chromosomal abnormalities, and 85% for severe structural defect
Consequences of presentation with advanced HIV disease in pregnancy : data from a national study in Italy
Among 469 women with a diagnosis of HIV in pregnancy, 74 (15.8%) presented with less than 200 CD4 cells per cubic millimeter. The only variable significantly associated with this occurrence was African origin (odds ratio: 2.22, 95% confidence intervals: 1.32 to 3.75, P = 0.003). Four women with low CD4 (5.6%), compared with none with higher CD4 counts, had severe AIDS-defining conditions (P < 0.001) during pregnancy or soon after delivery, and one transmitted HIV to the newborn. Early preterm delivery (<32 weeks) was significantly more frequent with low CD4 (6.2% vs. 1.4%, P = 0.015). An earlier access to HIV testing, particularly among immigrants of African origin, can prevent severe HIV-related morbidity
Infectious diseases among foreign prisoners: results of a hospital-based management model in Palermo
Foreign prisoners have a high vulnerability in terms of morbidity and access to care in overcrowded Italian prisons. This paper presents and comments on the management model of infectious diseases in foreign prisoners at our outpatient clinic, in order to describe a model of management for these conditions. Overall, 133 subjects (mean age 35.5 years) from 29 countries were followed for a period of 15 years. The most commonly represented area of origin (54.1%) was the Maghreb region. HCV infection (40.6%), HIV (22.5%), HBV (9.8%) and co-infection (15%, HIV/HCV or HIV/HBV) were observed. Ten subjects had tuberculosis, and only 30% of them were compliant with the treatment. Only 46.3% of HCV mono-infected patients completed the entire diagnostic process and even a lower percentage (37%) of them took treatment regularly. 90% of HBV mono-infected patients and 84% of those HIV mono- and co-infected completed the diagnostic workout. 77% of patients in each group took therapy regularly. Overall, the results show limited effectiveness. Therefore, it would be necessary to improve communication between healthcare professionals and correctional systems. Moreover, it appears urgent to reduce overcrowding in prisons to limit morbidity in prisoners
Modeling spatially resolved data of methane catalytic partial oxidation on Rh foam catalyst at different inlet compositions and flowrates
Spatially resolved species and temperature profiles measured for a wide range of inlet stoichiometries and flowrates are compared with microkinetic numerical simulations to investigate the effect of transport phenomena on the catalytic partial oxidation of methane on Rh foam catalysts. In agreement with the experimental data, the species profiles calculated at different C/O inlet stoichiometries show that both partial oxidation products (H2, CO) and total oxidation products (H2O, CO2) are formed in the presence of oxygen. At the leaner stoichiometries, both oxygen and methane react in the diffusive regime at the catalyst entrance. At the richest methane stoichiometry (high C/O), surface temperatures are lower and methane consumption is only partly determined by transport. For all stoichiometries, a kinetically controlled regime prevails in the downstream reforming zone after O2 is fully consumed. The effect of increasing the flowrate shifts all species profiles downstream and also slightly modifies the shapes of the axial profiles, due to the different effectiveness of heat and mass transfer. Despite enhanced mass transfer and increased surface temperature, the shortened contact time causes a reduced CH4 conversion at high flowrates. The effect of flowrate on the dominant regime is investigated, for both reactants, comparing the resistances calculated in the pure transport regime and in the pure kinetic regime. From a chemical point of view, the model allows for the analysis of the reaction path leading to hydrogen. Due to inhibition of H2O re-adsorption, it can be proven that H2 can be a primary product even in the presence of gas phase O2. The analysis of the surface coverages shows analogous effects on the profiles when decreasing C/O or increasing flow, because in both cases the surface temperature is increased. Syngas selectivity was also evaluated, both from measured and calculated profiles. SH2 is well described by the model at each stoichiometry and flowrate, while SCO is underestimated in every case. From this work, it is also indicated that the Rh catalyst works with CO (measured) selectivities higher than equilibrium. Carbon dioxide only forms in the oxidation zone, for C/O = 1 and 1.3, but in the rest of the catalyst zone, there is no further production despite what would be expected from equilibrium. This confirms Rh does not catalyze the water gas shift reaction. On the other hand, at C/O = 0.8, this reaction becomes active, due to the higher temperature, and the CO2 is also produced in the reforming zone. This suggests that CO2 will not rise after the oxidation section if the surface temperature is kept sufficiently low. Sensitivity analyses to the active catalytic surface and to the kinetic parameters are provided
Modeling spatially resolved profiles of methane partial oxidation on a Rh foam catalyst with detailed chemistry
Using spatially resolved measurements of temperature and concentration, we critically analyzed the chemistry and transport limitations in the partial oxidation of methane (POM) reaction carried out on Rh, supported on a foam catalyst. The analysis was based on two models, both sharing a detailed surface chemistry but with different gas-surface transport processes. The simulation neglecting transport limitations correctly predicts the outlet concentrations, apparently because of the approach to equilibrium, but significant disagreement was found along the catalysts, particularly in the initial region, demonstrating the existence of regions in which strong diffusive limitation! prevail. We developed a pseudo-1D model that can differentiate the species and temperature in the hulk of the gas and at the surface and describe heat (including radiation) and mass transport through correlations with ad hoc parameters based on experimental studies. With this model, we correctly predicted the profiles along the reactor for all species. Only CO2 had a relevant relative error, but its composition was very low. The solid temperature was well reproduced as well, whereas the gas temperature was somewhere higher than the experimental temperature, possibly due to overestimation of the heat transport coefficient. Analysis of the transport limitations found that O-2 and H2O had large concentration gradients between gas and surface due to their involvement in the total oxidation, which is a very fast reaction. The analysis thus demonstrated that production and consumption rates at the catalytic surface were frequently sufficiently high so as to enter a diffusive regime. Accordingly, we highlight the need to augment the implementation of detailed surface chemistry with some accounting of the transport processes of both mass and heat. In addition, we show that the Chilton-Colburn analogy can be seriously misleading under these conditions of locally fast heterogeneous kinetics. (C) 2008 Elsevier Inc. All rights reserved
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