A comparative study of N2O conversion to N-2 over Co/AC and Cu/AC catalysts

Catalytic conversion of N2O to N-2 over Cu- and Co-impregnated activated carbon catalysts (Cu/AC and Co/AC) was investigated. Catalytic activity measurements were carried out in a fixed-bed flow reactor at atmospheric pressure. The catalysts were characterized by N-2 adsorption, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). This study aimed to provide insights into the following aspects: the metal dispersion, changes in pore structure, influence of catalyst loading on reaction, and reaction mechanism. Increasing loading of Co or Cu led to decreasing dispersion, but 20 wt % loading was an upper limit for optimal activities in both cases, with too high loading causing sintering of metal. Co exhibited a relatively better dispersion than Cu. Impregnation of metal led to a large decrease in surface area and pore volume, especially for 30 wt % of loading. 20 wt % of loading has proved to be the optimum for both Cu and Co, which shows the highest activity. Both N2O-Co/AC and -Cu/AC reactions are based upon a redox mechanism, but the former is limited by the oxygen transfer from catalysts to carbon, while N2O chemisorption on the surface of Cu catalyst controls the latter. The removal of oxygen from cobalt promotes the activity of Co/AC, but it is beneficial for Cu/AC to keep plenty of oxygen to maintain the intermediate oxidation of copper-Cu1+. The different nature of the two catalysts and their catalytic reaction mechanisms are closely related to their different electronegativities.

Effects of promoters on catalytic activity and carbon deposition of Ni/gamma-Al2O3 catalysts in CO2 reforming of CH4

Catalytic reforming of methane with carbon dioxide was studied in a fixed-bed reactor using unpromoted and promoted Ni/gamma-Al2O3 catalysts. The effects of promoters, such as alkali metal oxide (Na2O), alkaline-earth metal oxides (MgO, CaO) and rare-earth metal oxides (La2O3, CeO2), on the catalytic activity and stability in terms of coking resistance and coke reactivity were systematically examined. CaO-, La2O3- and CeO2-promoted Ni/gamma-Al2O3 catalysts exhibited higher stability whereas MgO- and Na2O-promoted catalysts demonstrated lower activity and significant deactivation. Metal-oxide promoters (Na2O, MgO, La2O3, and CeO2) suppressed the carbon deposition, primarily due to the enhanced basicities of the supports and highly reactive carbon species formed during the reaction. In contrast, CaO increased the carbon deposition; however, it promoted the carbon reactivity. (C) 2000 Society of Chemical Industry.

Residence time distributions of gas flowing through rotating drum bioreactors

Residence time distribution studies of gas through a rotating drum bioreactor for solid-state fermentation were performed using carbon monoxide as a tracer gas. The exit concentration as a function of time differed considerably from profiles expected for plug flow, plug flow with axial dispersion, and continuous stirred tank reactor (CSTR) models. The data were then fitted by least-squares analysis to mathematical models describing a central plug flow region surrounded by either one dead region (a three-parameter model) or two dead regions (a five-parameter model). Model parameters were the dispersion coefficient in the central plug flow region, the volumes of the dead regions, and the exchange rates between the different regions. The superficial velocity of the gas through the reactor has a large effect on parameter values. Increased superficial velocity tends to decrease dead region volumes, interregion transfer rates, and axial dispersion. The significant deviation from CSTR, plug flow, and plug flow with axial dispersion of the residence time distribution of gas within small-scale reactors can lead to underestimation of the calculation of mass and heat transfer coefficients and hence has implications for reactor design and scaleup. (C) 2001 John Wiley & Sons, Inc.

Synthesis of anatase TiO2 supported on porous solids by chemical vapor deposition

Coating anatase TiO2 onto three different particle supports, activated carbon (AC), gamma -alumina (Al2O3) and silica gel (SiO2), by chemical vapor deposition (CVD) was studied. The effect of the CVD synthesis conditions on the loading rate of anatase TiO2 was investigated. It was found that introducing water vapor during CVD or adsorbing water before CVD was crucial to obtain anatase TiO2 on the surface of the particle supports. The evaporation temperature of precursor, deposition temperature in the reactor, flow rate of carrier gas, and the length of coating time were also important parameters to obtain more uniform and repeatable TiO2 coating. High inflow precursor concentration, high CVD reactor temperature and long coating time tended to cause block problem. Coating TiO2 onto small particles by CVD involved both chemical vapor deposition and particle deposition. It was believed that the latter was the reason for the block problem. In addition, the mechanism of CVD process in this study included two parts, pyrolysis and hydrolysis, and one of them was dominant in the CVD process under different synthesis route. Among the three types of materials, silica gel, with higher surface hydroxyl groups and macropore surface area, was found to be the most efficient support in terms of both anatase TiO2 coating and photocatalytic reaction. (C) 2001 Elsevier Science B.V. All rights reserved.

Oxidation of toluene in waste gas streams using mesoporous Ti-hexagonal mesoporous silica

Various mesoporous catalysts with titanium loadings between 0.5 and 4 Ti wt. % and surface areas between 600 and 1,600 m(2)/g were synthesized using the molecular designed dispersion technique. These catalysts were tested using toluene oxidation in a fixed bed reactor at temperatures between 300 and 550degreesC. The reaction products were found to be CO2 and CO with selectivity towards CO2 above 80% for all catalysts. The catalytic activity of the catalysts increases with titanium loading. The total conversion at 550degreesC was not affected by the textural porosity, but increased textural porosity did significantly reduce the ignition temperature by up to 50degreesC. The Thiele modulus was calculated to be much less than one for all these materials indicating that the reaction rate is not diffusion, limited.

Fermentative production of hydrogen from cassava processing wastewater by Clostridium acetobutylicum

This work reports on the effect of initial substrate concentration on COD consumption, pH, and H(2) production during cassava processing wastewater fermentation by Clostridium acetobutylicum ATCC 824. Five initial COD wastewater concentrations, namely 5.0, 7.5, 10.7, 15.0, and 30.0 g/L, were used. The results showed that higher substrate concentrations (30.0 and 15.0 COD/L) led to lower H(2) yield as well as less efficient substrate conversion into H(2). On the other hand, initial COD concentrations of 10.7, 7.5 and 5 g/L furnished 1.34, 1.2 and 2.41 mol H(2)/mol glucose, with efficiency of glucose conversion into H(2) of 34, 30, and 60% (mol/mol), respectively. These results demonstrate that cassava processing wastewater, a highly polluting effluent, can be successfully employed as substrate for H(2) production by C acetobutylicum at lower COD concentrations. (C) 2011 Elsevier Ltd. All rights reserved.

Measurements of adipocity and high blood pressure among children and adolescents living in Belo Horizonte

Objective: To verify an association, if it exists, between obesity and blood pressure raised beyond the 90th percentile in children and adolescents, and to determine the measure of adiposity that best correlates with blood pressure in these subjects. Design: Cross-sectional study. Setting: A school-based study in Belo Horizonte, Brazil. Participants: We selected randomly 1,403 students, aged from 6 to 18 years, from 545,046 students attending 521 public and private schools. Those selected completed the study. Main measures of outcome: We recorded the weight, height, skin fold in the triceps, subscapular, and suprailiac areas, waist and hip circumference, body-mass index, and resting systolic and diastolic blood pressures using a mercury sphygmomanometer. Results: In univariate analyses, body mass index greater or lesser than 85th percentile, measurements of skin thickness in the subscapular and suprailiac areas, and the sum of all measurements of skinfold thickness, were associated with both systolic and diastolic measurements of blood pressure. After multivariate analyses that adjusted for all measurements of adiposity except itself, and age, race, and socioeconomic state, we found that the increased body mass index was associated with a 3.6-fold increased frequency of elevated systolic measurements of blood pressure, with 9596 confidence intervals from 2.2 to 5.8, and a 2.7-fold increased frequency of elevated measurements of diastolic blood pressure, with 95% confidence intervals from 1.9 to 4.0. Conclusions: Body-mass index serves as a better predictor of elevated blood pressure among children than do local measurements of adiposity.

Clinical profile of patients enroled in a cell therapy trial for severe coronary artery disease

Aims and objectives. To compare the clinical profile of patients included in a clinical trial of autologous bone marrow cells as an adjunctive therapy to coronary artery bypass grafting with that of patients undergoing routine coronary artery bypass grafting. Background. The therapeutic potential of autologous bone marrow cells has been explored in the treatment of severe coronary artery disease. There are few data regarding the clinical and socio-economic profile of patients included in clinical trials using bone marrow cell. Design. Case-control study. Method. Sixty-seven patients (61 SD 9) years, 82% men) with multivessel coronary artery disease were divided into two groups: patients in the bone marrow cell group (n = 34) underwent incomplete coronary artery bypass grafting + intramyocardial injection of autologous bone marrow cells (lymphomonocytic fraction -2.0 (SD 0.2 x 108) cells/patient) in the ischaemic, non-revascularised myocardium, whereas patients in the coronary artery bypass grafting group (n = 33) underwent routine bypass surgery. Demographics, socio-economic status, clinical and echocardiographic data were collected. Statistical analysis included the Fisher`s exact test (categorical variables) and the Student`s t-test (continuous variables). Results. There were no significant differences between groups regarding age, gender, BMI, heart rate, blood pressure and echo data. There was a greater prevalence of obesity (65 vs. 33%; OR = 3.7 [1.3-10.1]), of previous myocardial infarction (68 vs. 39%; OR = 3.2 [1.2-8.8]) and prior revascularisation procedures (59 vs. 24%; OR = 4.5 [1.6-12.7]) in the autologous bone marrow cells group and of smokers in the coronary artery bypass grafting group (51 vs. 23%; OR = 3.5 [1.2-10.4]). Conclusions. Patients included in this clinical trial of autologous bone marrow cells for severe coronary artery disease presented a greater prevalence of myocardial revascularisation procedures, indicating a more severe clinical presentation of the disease. Fewer smokers in this group could be attributable to life style changes after previous cardiovascular events and/or interventions. Relevance to clinical practice. The knowledge of the clinical profile of patients included in cell therapy trials may help researchers in the identification of patients that may be enroled in future clinical trials of this new therapeutic strategy.

Outpatient Radioiodine Therapy for Thyroid Cancer A Safe Nuclear Medicine Procedure

Purposes: To evaluate the dosimetric effect of outpatient radioiodine therapy for thyroid cancer in members of a patient`s family and their living environment, when using iodine-131 doses reaching 7.4 GBq. The following parameters were thus defined: (a) whole-body radiation doses to caregivers, (b) the production of contaminated solid waste, and (c) radiation potential and surface contamination within patients` living quarters. Methods: In total, 100 patients were treated on an outpatient basis, taking into consideration their acceptable living conditions, interests, and willingness to comply with medical and radiation safety guidelines. Both the caregivers and the radiation dose potentiality inside patients` residences were monitored by using thermoluminescent dosimeters. Surface contamination and contaminated solid wastes were identified and measured with a Geiger-Muller detector. Results: A total of 90 monitored individuals received a mean dose of 0.27 (+/- 0.28) mSv, and the maximum dose registered was 1.6 mSv. The mean value for the potential dose within all living quarters was 0.31(+/- 0.34) mSv, and the mean value per monitored surface was 5.58 Bq/cm(2) for all the 1659 points measured. The overall production of contaminated solid wastes was at a low level, being about 3 times less than the exemption level indicated by the International Atomic Energy Agency. Conclusions: This study indicates that the treatment of thyroid cancer by applying radioiodine activities up to 7.4 GBq, on an outpatient basis, is a safe procedure, especially when supervised by qualified professionals. This alternative therapy should be a topic for careful discussion considering the high potential for reducing costs in healthcare and improving patient acceptance.

Design analysis for refolding monomeric protein

Renaturation of protein expressed as inclusion bodies within Escherichia coli is a key step in many bioprocesses. Operating conditions for the refolding step dramatically affect the amount of protein product recovered, and hence profoundly influence the process economics. The first systematic comparison of refolding conducted in batch, fed-batch and continuous stirred-tank reactors is provided Refolding is modeled as kinetic competition between first-order refolding (equilibrium reaction) and irreversible aggregation (second-order). Simulations presented allow direct comparison between different flowsheets and refolding schemes using a dimensionless economic objective. As expected from examination of the reaction kinetics, batch operation is the most inefficient merle. For the base process considered, the overall cost of fed-batch and continuous refolding is virtually identical (less than half that of the batch process). Reactor selection and optimization of refolding using overall economics are demonstrated to be vitally important.

Evaluation of interventions to reduce catheter-associated bloodstream infection: Continuous tailored education versus one basic lecture

Background: This study evaluated the impact of 2 models of educational intervention on rates of central venous catheter-associated bloodstream infections (CVC-BSIs). Methods: This was a prospective observational study conducted between January 2005 and June 2007 in 2 medical intensive care units (designated ICU A and ICU B) in a large teaching hospital. The study was divided into in 3 periods: baseline (only rates were evaluated), preintervention (questionnaire to evaluate knowledge of health care workers [HCWs] and observation of CVC care in both ICUs), and intervention (in ICU A, tailored, continuous intervention; in ICU B, a single lecture). The preintervention and intervention periods for each ICU were compared. Results: During the preintervention period, 940 CVC-days were evaluated in ICUA and 843 CVC-days were evaluated in ICU B. During the intervention period, 2175 CVC-days were evaluated in ICUA and 1694 CVC-days were evaluated in ICU B. Questions regarding CVC insertion, disinfection during catheter manipulation, and use of an alcohol-based product during dressing application were answered correctly by 70%-100% HCWs. Nevertheless, HCWs` adherence to these practices in the preintervention period was low for CVC handling and dressing, hand hygiene (6%-35%), and catheter hub disinfection (45%-68%). During the intervention period, HCWs` adherence to hand hygiene was 48%-98%, and adherence to hub disinfection was 82%-97%. CVC-BSI rates declined in both units. In ICUA, this decrease was progressive and sustained, from 12CVC-BSIs/1000 CVC-days at baseline to 0 after 9 months. In ICU B, the rate initially dropped from 16.2 to 0 CVC-BSIs/1000 CVC-days, but then increased to 13.7 CVC-BSIs/1000 CVC-days. Conclusion: Personal customized, continuous intervention seems to develop a ""culture of prevention"" and is more effective than single intervention, leading to a sustained reduction of infection rates.

Vascular endothelial growth factor and beta-human chorionic gonadotropin are associated with trophoblastic invasion into the tubal wall in ectopic pregnancy

Objective: To assess the association between the depth of trophoblastic penetration into the tubal wall with serum concentrations of vascular endothelial growth factor (VEGF) and beta-hCG and to assess its predictive value. Design: Prospective study. Setting: Tertiary care university hospital. Patient(s): Thirty patients with ampullary pregnancy undergoing salpingectomy were analyzed. Intervention(s): Trophoblastic invasion was histologically classified as stage I when limited to the tubal mucosa, stage II when extending to the muscle layer, and stage III in the case of complete tubal wall infiltration. Main Outcome Measure(s): The relation between depth of trophoblastic infiltration into the tubal wall with VEGF and beta-hCG serum concentrations on the day of surgery. Result(s): An association between the depth of trophoblastic invasion and maternal serum concentrations of VEGF and beta-hCG was observed. VEGF levels of 297.2 pg/mL showed 100.0% sensitivity and 90.0% specificity for stage I, and levels of 440.1 pg/mL showed 81.8% sensitivity and 88.8% specificity for stage III. Beta-hCG levels of 2590.0 mIU/mL showed 88.9% sensitivity and 80.0% specificity for stage I, and levels of 10,827.0 mUI/mL showed 72.7% sensitivity and 88.9% specificity for stage III. Conclusion(s): Maternal serum VEGF and beta-hCG concentrations are associated with depth of trophoblastic penetration into the tubal wall. (Fertil Steril (R) 2010;94:1595-600. (C) 2010 by American Society for Reproductive Medicine.)

Ex Vivo Lung Perfusion: Early Report of Brazilian Experience

Introduction. Only about 15% of the potential candidates for lung donation are considered suitable for transplantation. A new method for ex vivo lung perfusion (EVLP) can be used to evaluate and recondition ""marginal,"" nonacceptable lungs. We have herein described an initial experience with ex vivo perfusion of 8 donor lungs deemed nonacceptable. Materials and Methods. After harvesting, the lungs were perfused ex vivo with Steen Solution, an extracellular matrix with high colloid osmotic pressure. A membrane oxygenator connected to the circuit received gas from a mixture of nitrogen and carbon dioxide, maintaining a normal mixed venous blood gas level in the perfusate. The lungs were gradually rewarmed, reperfused, and ventilated for evaluation through analyses of oxygenation capacity, pulmonary vascular resistance (PVR), lung compliance (LC), and biopsy. Results. The arterial oxygen pressure (with inspired oxygen fraction of 100%) increased from a mean of 206 mm Hg in the organ donor at the referring hospital to a mean of 498 mm Hg during the ex vivo evaluation. After 1 hour of EVLP, PVR varied from 440-1454 dynes/sec/cm(5); LC was in the range of 26-90 mL/cmH(2)O. There was no histological deterioration after 10 hours of cold ischemia and 1 hour of EVLP. Conclusions. The ex vivo evaluation model can improve oxygenation capacity of ""marginal"" lungs rejected for transplantation. It has great potential to increase lung donor availability and, possibly, reduce time on the waiting list.

Cost-Effectiveness of Palliation of Unresectable Esophageal Cancer

Introduction Different modalities of palliation for obstructive symptoms in patients with unresectable esophageal cancer (EC) exist. However, these therapeutic alternatives have significant differences in costs and effectiveness. Methods A Markov model was designed to compare the cost-effectiveness (CE) of self-expandable stent (SES), brachytherapy and laser in the palliation of unresectable EC. Patients were assigned to one of the strategies, and the improvement in swallowing function was compared given the treatment efficacy, probability of survival, and risks of complications associated to each strategy. Probabilities and parameters for distribution were based on a 9-month time frame. Results Under the base-case scenario, laser has the lowest CE ratio, followed by brachytherapy at an incremental cost-effectiveness ratio (ICER) of $4,400.00, and SES is a dominated strategy. In the probabilistic analysis, laser is the strategy with the highest probability of cost-effectiveness for willingness to pay (WTP) values lower than $3,201 and brachytherapy for all WTP yielding a positive net health benefit (NHB) (threshold $4,440). The highest probability of cost-effectiveness for brachytherapy is 96%, and consequently, selection of suboptimal strategies can lead to opportunity losses for the US health system, ranging from US$ 4.32 to US$ 38.09 million dollars over the next 5-20 years. Conclusion Conditional to the WTP and current US Medicare costs, palliation of unresectable esophageal cancers with brachytherapy provides the largest amount of NHB and is the strategy with the highest probability of CE. However, some level of uncertainly remains, and wrong decisions will be made until further knowledge is acquired.

GD1b-Derived Gangliosides Modulate Fc epsilon RI Endocytosis in Mast Cells

The role of the mast cell-specific gangliosides in the modulation of the endocytic pathway of Fc epsilon RI was investigated in RBL-2H3 cells and in the ganglioside-deficient cell lines, E5 and D1. MAb BC4, which binds to the alpha subunit of Fc epsilon RI, was used in the analysis of receptor internalization. After incubation with BC4-FITC for 30 min, endocytic vesicles in RBL-2H3 and E5 cells were dispersed in the cytoplasm. After 1 hr, the endocytic vesicles of the RBL-2H3 cells had fused and formed clusters, whereas in the E5 cells, the fusion was slower. In contrast, in D1 cells, the endocytic vesicles were smaller and remained close to the plasma membrane even after 3 hr of incubation. When incubated with BC4-FITC and subsequently imunolabeled for markers of various endocytic compartments, a defect in the endocytic pathway in the E5 and D1 cells became evident. In the D1 cells, this defect was observed at the initial steps of endocytosis. Therefore, the ganglioside derivatives from GD1b are important in the endocytosis of Fc epsilon RI in mast cells. Because gangliosides may play a role in mast cell-related disease processes, they provide an attractive target for drug therapy and diagnosis. (J Histochem Cytochem 59:428-440, 2011)