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•A detailed reaction network for one-step ethanol-to-1,3-butadiene conversion on mixed Hf-Zn catalyst is obtained.•Catalyst deactivation by deposition of aromatic-type coke and ...reduction of Zn2+ sites to Zn0 with TOS.•Zn2+ reduction induces Zn2+/Hf4+ site misbalance, altering catalyst selectivity with TOS.•Calcination with air removes coke and re-oxidizes part of Zn0 back to Zn2+ but Zn2+/Hf4+ site balance is not re-established.•The suitability of by-product recycling for process design is assessed by experiments co-feeding by-products and ethanol.
Some fundamental and practical aspects of a Hf-Zn catalyst, with a nominal composition of 3.0 wt% Hf and 9.3 wt% Zn, and prepared as a physical mixture of Hf/SiO2 (85 wt%) and the zinc-silicate hemimorphite (15 wt%), have been studied for the one-step conversion of ethanol to 1,3-butadiene. The elucidation of the main reactions leading to 1,3-butadiene and by-products was made by means of kinetic curves and catalytic tests where intermediates were individually fed. In addition, the convenience of by-product separation from unreacted ethanol in an industrial process was studied by performing experiments where ethanol was co-fed with intermediates. The causes of catalyst deactivation and the impact on catalyst structure and performance of regeneration by calcination were also investigated. According to our results, the pathway to 1,3-butadiene over the Hf-Zn catalyst includes ethanol dehydrogenation, acetaldehyde aldol condensation, crotonaldehyde reduction with ethanol, and crotyl alcohol dehydration. The recycling of the by-products butanal, acetone and 1-butanol into the reactor should be avoided, as the first two are converted to heavy compounds by aldol condensation reactions, while 1-butanol dehydration leads to butenes, which are difficult to separate from 1,3-butadiene. The suppression of diethyl ether formation from ethanol by recycling to extinction is possible. It has been found that catalyst deactivation is mainly caused by the retention of oxygenated aromatic-type coke species, preferentially formed on the dehydrogenating Zn2+ sites associated with the hemimorphite component of the catalyst, and probably also by a loss in Zn2+ sites due to the reduction to Zn° during catalysis. This reduction induces an imbalance between Hf4+ and Zn2+ sites, which changes catalyst selectivity. Regeneration by calcination with air removes coke and re-oxidizes a fraction of Zn° back to Zn2+, but it does not fully re-establish the original Zn2+/Hf4+ balance.
One of the separation processes used for the production and purification of hydrogen is molecular sieve adsorption using the Pressure Swing Adsorption (PSA) method. The process uses two beds ...containing activated carbon and a sequence of four steps (adsorption, depressurization, purge, and repressurization) for hydrogen production and purification. The initial composition is 0.11 CO, 0.61 H2, and 0.28 CH4 in molar fractions. The aim of this work is to bring the purity of hydrogen to 0.99 in molar fraction and implement controllers that can maintain the desired purity even in the presence of the disturbances that occur in the PSA process. The controller design (discrete PID and state feedback control) was based on the Hammerstein–Wiener model, which had an 80% fit over the rigorous PSA model. Both controllers were validated on a virtual plant of the PSA process, showing great performance and robustness against disturbances. The results obtained show that it is possible to follow the desired trajectory and attenuate double disturbances, while managing to maintain the purity of hydrogen at a value of 0.99 in molar fraction, which meets the international standards to be used as a biofuel.
Very little information is available on the involvement of newly characterized adipokines in human immunodeficiency virus (HIV)/antiretroviral therapy (ART)-associated lipodystrophy syndrome (HALS). ...Our aim was to determine whether apelin, apelin receptor, omentin, RBP4, vaspin and visfatin genetic variants and plasma levels are associated with HALS. We performed a cross-sectional multicentre study that involved 558 HIV type 1–infected patients treated with a stable highly active ART regimen, 240 of which had overt HALS and 318 who did not have HALS. Epidemiologic and clinical variables were determined. Polymorphisms in the apelin, omentin, RBP4, vaspin and visfatin genes were assessed by genotyping. Plasma apelin, apelin receptor, omentin, RBP4, vaspin and visfatin levels were determined by enzyme-linked immunosorbent assay in 163 patients (81 with HALS and 82 without HALS) from whom stored plasma samples were available. Student's t test, one-way ANOVA, chi-square test, Pearson and Spearman correlations and linear regression analysis were used for statistical analyses. There were no associations between the different polymorphisms assessed and the HALS phenotype. Circulating RBP4 was significantly higher (p < 0.001) and plasma omentin was significantly lower (p 0.001) in patients with HALS compared to those without HALS; differences in plasma levels of the remaining adipokines were nonsignificant between groups. Circulating RBP4 concentration was predicted independently by the presence of HALS. Apelin and apelin receptor levels were independently predicted by body mass index. Visfatin concentration was predicted independently by the presence of acquired immunodeficiency syndrome. HALS is associated with higher RBP4 and lower omentin in plasma. These two adipokines, particularly RBP4, may be a link between HIV/ART and fat redistribution syndromes.
Gene expression studies of subcutaneous adipose tissue may help to better understand the mechanisms behind body fat changes in HIV-infected patients who initiate antiretroviral therapy (ART). Here, ...we evaluated early changes in adipose tissue gene expression and their relationship to fat changes in ART-naive HIV-infected patients randomly assigned to initiate therapy with emtricitabine/tenofovir plus efavirenz (EFV) or ritonavir-boosted lopinavir (LPV/r). Patients had abdominal subcutaneous adipose tissue biopsies at baseline and week 16 and dual-energy-X-ray absorptiometry at baseline and weeks 16 and 48. mRNA changes of 11 genes involved in adipogenesis, lipid and glucose metabolism, mitochondrial energy, and inflammation were assessed through reverse transcription-quantitative PCR (RT-qPCR). Additionally, correlations between gene expression changes and fat changes were evaluated. Fat increased preferentially in the trunk with EFV and in the limbs with LPV/r (P < 0.05). After 16 weeks of exposure to the drug regimen, transcripts of CEBP/A, ADIPOQ, GLUT4, LPL, and COXIV were significantly down-regulated in the EFV arm compared to the LPV/r arm (P < 0.05). Significant correlations were observed between LPL expression change and trunk fat change at week 16 in both arms and between CEBP/A or COXIV change and trunk fat change at the same time point only in the EFV arm and not in the LPV/r arm. When combined with emtricitabine/tenofovir as standard backbone therapy, EFV and LPV/r induced differential early expression of genes involved in adipogenesis and energy metabolism. Moreover, these mRNA expression changes correlated with trunk fat change in the EFV arm. (This was a substudy of a randomized clinical trial LIPOTAR study registered at ClinicalTrials.gov under identifier NCT00759070.).
INTRODUCTIONThe use of oral anticoagulants in patients with a history of atrial fibrillation (AF) and intracranial haemorrhage (ICH) is controversial on account of the risk of haemorrhagic stroke ...recurrence. This study presents our experience regarding the safety and efficacy of percutaneous left atrial appendage closure (LAAC), an alternative to anticoagulation in these patients. METHODSWe conducted a retrospective, single-centre, observational study. LAAC was performed in patients with a history of ICH and non-valvular AF. Risk of ischaemic and haemorrhagic events was estimated using the CHA2DS2-VASc and HAS-BLED scales. We recorded periprocedural complications, IHC recurrence, cerebral/systemic embolism, mortality and use of antithrombotic drugs following the procedure. RESULTSLAAC was performed in 9 patients (7 men, 2 women) using the AMPLATZER Amulet device in 7 cases and the AMPLATZER Cardiac Plug device in 2. Mean age was 72.7±8.2 years. Time between ICH and LAAC was less than one month in 5 patients and more than one month in 4 patients. Median CHA2DS2-VASc score was 4 (interquartile range of 2.5). Median HAS-BLED score was 3 (interquartile range of 0). No periprocedural complications were recorded. All patients received single anti-platelet therapy (clopidogrel in 5 patients, aspirin in 4) after the procedure; 5 patients received this treatment for 6 months and 4 received it indefinitely. No ischaemic or haemorrhagic events were recorded during follow-up (mean duration of 15 months). CONCLUSIONSIn our series, LAAC was found to be safe and effective in patients with a history of ICH who required anticoagulation due to AF.
Ex vivo analysis of mitochondrial function may reveal HIV progression and the impact of ART. We propose a mitochondrial and apoptotic in vitro model using Jurkat T cells incubated with plasma. The ...objectives of this study were to evaluate mitochondrial and apoptotic lesions in this model in relation to HIV progression, and to assess the effect of >1 year of standard non-thymidine-containing therapy.
This was a cross-sectional comparison among three age- and gender-matched groups (n = 19 × 3): healthy non-HIV-infected participants, HIV-infected long-term non-progressors (LTNPs) and standard antiretroviral-naive chronically infected patients standard progressors (Sps), longitudinally evaluated before (Sp1) and after (Sp2) >1 year of efavirenz + tenofovir + emtricitabine therapy. We analysed mitochondrial DNA content by RT-PCR, mitochondrial function by spectrophotometry, mitochondrial protein synthesis by western blot analysis, mitochondrial dynamics by western blot analysis (MFN2), apoptotic transition pore formation by western blot analysis (VDAC-1) and mitochondrial membrane potential and annexin V/propidium iodide fluorescence by flow cytometry.
There was a decreasing non-significant trend towards lower mitochondrial parameters for HIV-infected values with respect to uninfected control reference values. HIV progression (LTNP versus Sp1) was associated with decreased mitochondrial genetic, functional and translational parameters, which partially recovered after treatment intervention (Sp2). Mitochondrial fusion showed a trend to decrease non-significantly in Sp patients compared with LTNP patients, especially after therapy. All apoptotic parameters showed a trend to increase in Sp1 with respect to LTNP, followed by recovery in Sp2.
We proposed an in vitro model for mitochondrial and apoptotic assessment to test the effects of HIV infection and its therapy, resembling in vivo conditions. This model could be useful for clinical research purposes.
Speed of administration conditions the effectiveness of intravenous fibrinolysis in treating acute ischaemic stroke. To reduce the risk of haemorrhagic complications, the intervention is ...contraindicated in certain cases, such as where the International Normalised Ratio (INR) is ≥ 1.7. This study aimed to determine the reliability of point-of-care INR readings (POC-INR) taken using the CoaguChek® XS portable coagulometer compared to laboratory results (L-INR).
We conducted a retrospective observational study of consecutive patients admitted to our centre with acute ischaemic stroke and who were treated with intravenous fibrinolysis, over a period of 4 years. Patients' INR was measured with a portable coagulometer and in the laboratory. Results were compared using the paired-sample t test; using L-INR results as a reference value, ROC analysis was performed to determine POC-INR with greater predictive value.
The study included 210 patients with a mean age of 74.3±11.5 years old; 18 (8.6%) were taking vitamin K antagonist oral anticoagulants (OAC). There were no significant differences between the 2 INR measurements in the population as a whole (POC-INR-L-INR difference: 0.001±0.085; P=.82). In subgroup analysis, the results coincided for patients taking OACs (0.001±0.081; P=.42) and those with L-INR ≤ 1.2 (0.008±0.081; P=.16). For L-INR>1.2, however, the portable coagulometer underestimated INR (0.058±0.095; P=.01). Through ROC analysis, POC-INR < 1.6 was found to be the cut-off point with greatest sensitivity (100%) and specificity (98.97%) for identifying patients eligible for intravenous fibrinolysis (L-INR < 1.7).
POC-INR shows a good correlation with L-INR. Our results suggest that the best threshold to predict an L-INR < 1.7 is POC-INR < 1.6. Internal validation studies for POC-INR should be considered in all treatment centres.
This paper studies key issues for the design of industrial ethanol to 1,3-butadiene two-step processes, focusing on the second catalytic reaction step, for which a Ta-SBA-15 catalyst was chosen as a ...representative of the new generation of two-step catalysts. The important practical aspects studied were: i) the effect of operating conditions and the presence of impurities (water) in the ethanol feedstock on the performance of the catalyst, ii) stability and regeneration of the catalyst, and iii) the development of a kinetic model that can be used as a tool for designing the industrial process. The results showed that there are large non-linear interacting effects between the reaction conditions (temperature, space velocity and ethanol/acetaldehyde mole ratio) which must be carefully selected to optimize the catalyst performance. When shifting from an anhydrous to an aqueous ethanol/acetaldehyde feed (7.5 wt% water), catalyst performance at high temperature barely changed while at low temperature, conversion of ethanol and acetaldehyde decreased. Water in the feed largely increased the stability of Ta-SBA-15 catalyst. Finally, a kinetic model of a fresh catalyst was developed, whose novelty lies in the use of kinetic equations that account for the effect of water in the feed on the catalyst performance.
•Study of interacting effects between reaction conditions and water presence in feed.•Water in feed decreases conversion but does not alter product selectivity.•Water in feed largely decreases deactivation rate of the catalyst.•A kinetic model of a fresh catalyst was developed which predicts water effect.•Modelling approach applicable to any other two-step catalyst.
Exosome-derived miR-21 was independently associated with CD4 T cell decline in HIV-1-infected elite controllers (OR 0.369, 95% CI 0.137–0.994, p = 0.049). Also, a negative correlation between miR-21 ...expression and MCP-1 level was found (r = −0.649, p = 0.020), while no correlation between soluble biomarkers or cellular immune activation was found.
We report the complete genome sequence of the first Mexican human coronavirus (HCoV) OC43, obtained by new-generation sequencing and a metagenomic approach, isolated from a child hospitalized with ...pneumonia. The genome is closely related to the other OC43 genome sequences available, ranging from 99.8% to 98.2% nucleotide sequence identity.
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