Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 742
Filter
1.
Article in English | MEDLINE | ID: mdl-38949980

ABSTRACT

Background: Chagas disease or American trypanosomiasis, caused by Trypanosoma cruzi and vectored by triatomines, affects millions of people worldwide. In endemic countries including Mexico, infections in domestic animals, such as dogs, may affect the risk of human disease when they serve as a source of infection to vectors that subsequently infect humans. Materials and Methods: We conducted a cross-sectional study of 296 dogs from two cities near the northern and southern borders of Mexico: Reynosa, Tamaulipas, and Tuxtla Gutierrez, Chiapas. Infection was measured based on testing of blood using T. cruzi quantitative PCR (qPCR) and up to three antibody detection assays. The StatPak immunochromatographic assay was used to screen samples and the indirect fluorescent antibody (IFA) and multiplex microsphere immunoassay (MIA) tests were used as secondary tests on all samples that screened positive and a subset of negatives. Serologic positivity was defined based on reactivity on at least two independent tests. Results: Of the 280 samples tested for parasite DNA, two (0.7%) were positive, one of which (0.4%) was confirmed as T. cruzi discrete typing unit TcIV. Overall, 72 (24.3%) samples were reactive for T. cruzi antibodies via StatPak of which 8 were also positive using MIA and 2 were also positive using IFA (including one of the PCR-positive dogs). Overall, nine dogs (3.4%) met study criteria of positivity based on either/both serology or PCR tests. Positive dogs were found in both regions of Mexico; five (2.7%) from Reynosa and four (3.6%) from Tuxtla Gutierrez. We found no association between infection status and state of origin, sex, age group, breed group, neighborhood, and whether other pets lived in the home. Conclusion: Our results re-emphasize dogs' utility as sentinels for T. cruzi in Mexico and underscore the need for improved veterinary diagnostic tests and parasite surveillance at the household level in endemic countries.

3.
Transplant Direct ; 10(7): e1662, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38911273

ABSTRACT

Background: Liver transplantation is an increasingly frequent surgical procedure, with elevated rates of postoperative incisional hernias ranging from 5% to 46%. There are numerous known risk factors for incisional hernia, including the type of incision, patient sex, and presence of comorbidities such as diabetes, ascites, older age, and the use of steroids. Most studies on the treatment of incisional hernias in patients who have undergone liver transplantation have shown consistently high rates of complications. Consequently, we propose the use of nonvascular fascia for the symptomatic treatment of incisional hernias in patients with concomitant liver transplantation. Methods: We performed our new technique on 8 patients, who had previously undergone liver transplantation, between January 2019 and January 2023. The patients were examined using imaging techniques during the follow-up period. Results: Of the 8 patients, 7 were liver transplant recipients and 1 was a combined liver-kidney transplant patient. The median donor age was 57 y (5-66 y), whereas the mean recipient age was 58 y (31-66 y). The median patient height and weight were 163 cm (117-185 cm) and 76 kg (17-104 kg), respectively. Immunosuppression did not change in fascia recipients. The median time between transplantation and hernia repair surgery was 41 mo (5-116 mo). The sizes of the aponeurotic defects varied from 6 × 6 to 25 × 20 cm. Two patients experienced complications: one experienced bulging that required reintervention and the other experienced surgical site seroma. There was no mortality related to the use of the technique, and none were reported during follow-up. Conclusions: With its promising results, nonvascularized fascial transplantation can be a successful treatment for incisional hernias in patients who had previously received a liver transplant.

4.
Mycorrhiza ; 34(3): 191-201, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38758247

ABSTRACT

Arbuscular mycorrhizal fungi (AMF) colonize biochar in soils, yet the processes governing their colonization and growth in biochar are not well characterized. Biochar amendment improves soil health by increasing soil carbon, decreasing bulk density, and improving soil water retention, all of which can increase yield and alleviate environmental stress on crops. Biochar is often applied with nutrient addition, impacting mycorrhizal communities. To understand how mycorrhizas explore soils containing biochar, we buried packets of non-activated biochar in root exclusion mesh bags in contrasting agricultural soils. In this greenhouse experiment, with quinoa (Chenopodium quinoa) as the host plant, we tested impacts of mineral nutrient (as manure and fertilizer) and biochar addition on mycorrhizal colonization of biochar. Paraglomus appeared to dominate the biochar packets, and the community of AMF found in the biochar was a subset (12 of 18) of the virtual taxa detected in soil communities. We saw differences in AMF community composition between soils with different edaphic properties, and while nutrient addition shifted those communities, the shifts were inconsistent between soil types and did not significantly influence the observation that Paraglomus appeared to selectively colonize biochar. This observation may reflect differences in AMF traits, with Paraglomus previously identified only in soils (not in roots) pointing to predominately soil exploratory traits. Conversely, the absence of some AMF from the biochar implies either a reduced tendency to explore soils or an ability to avoid recalcitrant nutrient sources. Our results point to a selective colonization of biochar in agricultural soils.


Subject(s)
Charcoal , Mycorrhizae , Soil Microbiology , Soil , Mycorrhizae/physiology , Soil/chemistry , Agriculture/methods , Chenopodium quinoa , Plant Roots/microbiology , Manure/microbiology , Manure/analysis
5.
Nutrients ; 16(10)2024 May 17.
Article in English | MEDLINE | ID: mdl-38794750

ABSTRACT

INTRODUCTION: Eating disorders (EDs) are mental health illnesses with a multifactorial origin. At present, no review of indexed publications studying their prevalence in Spain is available. MATERIAL AND METHODS: A scoping review (PROSPERO -CRD42019140884-) was carried out through systematic searches (MEDLINE, EMBASE and PsycINFO) until January 2022. Papers published in Spanish/English analysing the prevalence of EDs in Spain (population < 65 years) were selected. RESULTS: A total of 766 articles were identified (186 eliminated as duplicates). A total of 580 articles were analysed on the basis of title and abstract, and 67 articles were selected for full-text analysis. A total of 37 studies analysed the prevalence of EDs in Spain. CONCLUSIONS: This is the first scoping review to analyse the prevalence of EDs in Spain. Puberty and adolescence are the most extensively studied stages. There is a high heterogeneity in the use of ED screening tools and a paucity of information on diagnostic tools.


Subject(s)
Feeding and Eating Disorders , Humans , Spain/epidemiology , Feeding and Eating Disorders/epidemiology , Prevalence , Adolescent , Female , Male , Adult , Child , Young Adult , Middle Aged
6.
Phys Rev E ; 109(4-1): 044216, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38755915

ABSTRACT

The resonance of N linearly coupled damped Duffing oscillators with a constant frequency sinusoidal driving force acting on the first oscillator is studied analytically by calculating the fixed points of the corresponding dynamical system and numerically using a fourth-order multivariate Runge-Kutta method. For a chain with N oscillators, we establish a general recursion scheme in the form of a system of equations that relates the amplitudes of the oscillators and the driving frequency, capable of describing resonance curves. We consider in detail the case of an oscillator chain with N=2 for high values of the driving amplitude and stiffness, and find hysteretical unstable regions in the resonance curves. In this unstable driving frequency regime, analysis of the time series reveals the presence of nonlinear normal modes visible as beating quasiperiodic oscillations.

7.
Cancers (Basel) ; 16(10)2024 May 08.
Article in English | MEDLINE | ID: mdl-38791878

ABSTRACT

There are several well-described molecular mechanisms that influence cell growth and are related to the development of cancer. Chemokines constitute a fundamental element that is not only involved in local growth but also affects angiogenesis, tumor spread, and metastatic disease. Among them, the C-X-C motif chemokine ligand 12 (CXCL12) and its specific receptor the chemokine C-X-C motif receptor 4 (CXCR4) have been widely studied. The overexpression in cell membranes of CXCR4 has been shown to be associated with the development of different kinds of histological malignancies, such as adenocarcinomas, epidermoid carcinomas, mesenchymal tumors, or neuroendocrine neoplasms (NENs). The molecular synapsis between CXCL12 and CXCR4 leads to the interaction of G proteins and the activation of different intracellular signaling pathways in both gastroenteropancreatic (GEP) and bronchopulmonary (BP) NENs, conferring greater capacity for locoregional aggressiveness, the epithelial-mesenchymal transition (EMT), and the appearance of metastases. Therefore, it has been hypothesized as to how to design tools that target this receptor. The aim of this review is to focus on current knowledge of the relationship between CXCR4 and NENs, with a special emphasis on diagnostic and therapeutic molecular targets.

8.
Foods ; 13(10)2024 May 16.
Article in English | MEDLINE | ID: mdl-38790853

ABSTRACT

(1) Background: Grapes and their associated by-products (such as grape pomace, GP) stand out for their polyphenol content, which makes them a source of bioactive compounds with antioxidant capacity. The aim of this research was to determine if the inclusion of 50 g/kg of GP in the diet of hens could enrich eggs with antioxidants and to study its effect on internal and external egg quality parameters. (2) Methods: A trial was conducted with two genetic lines of hens, which were fed either a control diet or a diet containing 50 g/kg of GP. Performance, internal and external egg quality, and egg yolk content of vitamins E and A and gallic acid were determined. (3) Results: In eggs laid by hens fed a GP diet, Haugh units and yolk color scores were enhanced, and eggshells became thinner, but without affecting the breaking strength. No dietary effect was observed on the vitamin contents of the yolk. A higher gallic acid content was observed in the yolks of eggs laid by hens fed the GP diet, suggesting that some dietary phenolic compounds could be transferred to the eggs. Hen genetics influenced egg weight, albumen Haugh units, shell thickness, and α- and γ-tocopherol concentration in yolks. (4) Conclusions: Dietary inclusion of GP improved the internal quality of eggs, enriching yolks with a phenolic compound but reducing shell thickness.

9.
J Environ Manage ; 355: 120525, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38437743

ABSTRACT

Activated carbon (AC), renowned for its versatile applications in water treatment, air purification, and industrial processes, is a critical component in environmental remediation and resource recovery strategies. This study encompasses the process modeling of AC production using anthracite coal as a precursor, involving multiple activation stages at different operating conditions, coupled with a detailed techno-economic analysis aimed at assessing the operational feasibility and financial viability of the plant. The economic analysis explores the investigation of economic feasibility by performing a detailed cashflow and sensitivity analysis to identify key parameters influencing the plant's economic performance, including raw material and energy prices, operational and process parameters. Capital and operational costs are meticulously evaluated, encompassing raw material acquisition, labor, energy consumption, and equipment investment. Financial metrics like Net Present Value (NPV), Internal Rate of Return (IRR), and payout period (POP) are employed, and the results show that AC selling price, raw material cost and plant capacity are the most influential parameters determining the plant's feasibility. The minimum AC production cost of 1.28 $/kg is obtained, corresponding to coal flow rate of 14,550 kg/h. These findings provide valuable insights for stakeholders, policymakers, and investors seeking to engage in activated carbon production from anthracite.


Subject(s)
Charcoal , Environmental Restoration and Remediation , Coal , Investments , Plants
10.
Cir Esp (Engl Ed) ; 102(5): 265-274, 2024 May.
Article in English | MEDLINE | ID: mdl-38493929

ABSTRACT

INTRODUCTION: Controversy exists in the literature as to the best technique for pancreaticoduodenectomy (PD), whether pyloric preservation (PP-CPD) or Whipple's technique (with antrectomy [W-CPD]), the former being associated with a higher frequency of delayed gastric emptying (DGE). METHODS: Retrospective and comparative study between PP-CPD technique (n = 124 patients) and W-CPD technique (n = 126 patients), in patients who were operated for tumors of the pancreatic head and periampullary region between the period 2012 and 2023. RESULTS: Surgical time was longer, although not significant, with the W-CPD technique. Pancreatic and peripancreatic tumor invasion (p = 0.031) and number of lymph nodes resected (p < 0.0001) reached statistical significance in W-CPD, although there was no significant difference between the groups in terms of lymph node tumor invasion. Regarding postoperative morbimortality (medical complications, postoperative pancreatic fistula [POPF], hemorrhage, RVG, re-interventions, in-hospital mortality, Clavien-Dindo complications), ICU and hospital stay, no statistically significant differences were observed between the groups. During follow-up, no significant differences were observed between the groups for morbidity and mortality at 90 days and survival at 1, 3 and 5 years. Binary logistic regression analysis for DGE showed that binary relevant POPF grade B/C was a significant risk factor for DGE. CONCLUSIONS: Postoperative morbidity and mortality and long-term survival were not significantly different with PP-CPD and W-CPD, but POPF grade B/C was a risk factor for DGE grade C.


Subject(s)
Pancreatic Neoplasms , Pancreaticoduodenectomy , Pylorus , Humans , Pancreaticoduodenectomy/methods , Pancreaticoduodenectomy/adverse effects , Retrospective Studies , Male , Female , Pancreatic Neoplasms/surgery , Pancreatic Neoplasms/pathology , Middle Aged , Pylorus/surgery , Aged , Postoperative Complications/epidemiology , Organ Sparing Treatments/methods , Adult
11.
Animals (Basel) ; 14(3)2024 Feb 03.
Article in English | MEDLINE | ID: mdl-38338147

ABSTRACT

The bighorn sheep in Mexico is classified as at-risk by the Mexican federal government. In the state of Baja California, wild sheep can be observed throughout the length of the state from the USA-Mexico border south to the Agua de Soda mountain range. This research aimed to document the historical trend of the bighorn population based on aerial surveys conducted in 1992, 1995, 1999, 2010, and 2021, and the abundance, distribution, and structure of bighorn sheep populations in Baja California, based on an aerial survey conducted from 8-14 November 2021, covering thirteen mountain ranges. The estimated sheep population in 2021 was based on the number of individuals observed; the sightability of the animals; the area sampled; and the total area of habitat available. In 30.5 flight hours, 456 bighorn sheep were observed, with an estimated population of 1697 ± 80 individuals. The observation rate was 16 sheep sighted per hour of flight, and the ram:ewe:lamb ratio was 62:100:19. When the results of the 2021 flight were compared to the results of the previous aerial surveys, there was a large variation between the data, which was related to the lack of consistency between the sampling designs used in each study. Nevertheless, a statistical test of the results of aerial surveys conducted in the state suggest that the Baja California bighorn sheep population remained stable between 1992 and 2021. This study highlights the need to standardize wild sheep aerial surveys by defining flight paths and establishing a consistent duration of flights. On the other hand, Baja California authorities should consider modifying the current conservation strategy for bighorn sheep to increase the species' population in the state by initiating community-based wildlife conservation programs in rural communities.

12.
J Acoust Soc Am ; 155(2): 915-929, 2024 02 01.
Article in English | MEDLINE | ID: mdl-38310607

ABSTRACT

This paper presents the results of a listening experiment designed to assess annoyance and perceived loudness (PL) for several unmanned aircraft system (UAS) operations, with the listener simulated in indoor and outdoor positions. This research investigated (i) how participant responses change depending on UAS operation, (ii) which broadband metrics are most suitable for representing annoyance and PL, (iii) differences in noise level required to result in equal participant responses to different operations, and (iv) which sound quality metrics (SQMs) are significant for UAS noise perception. Results indicate annoyance and PL responses were greatest for landing operations with flyovers being the least annoying or loud. LAeq, LASmax, and loudness (N5) were the strongest predictors in representing annoyance. Offset analysis predicted small differences in annoyance responses between flyovers and other operations, but also indicated that flyovers would require an increase to LASmax of 3.3 to 6.3 dB compared to other operations to achieve equal PL. Loudness was the most significant SQM, with minor contributions from impulsivity for annoyance and PL when outside, and tonality for PL when indoors. These findings contribute to the understanding of UAS noise perception for the development of metrics and assessment methods accounting for the characteristics of UAS operations.


Subject(s)
Aircraft , Noise , Humans , Noise/adverse effects , Perception
14.
Dis Aquat Organ ; 157: 73-80, 2024 Feb 29.
Article in English | MEDLINE | ID: mdl-38421009

ABSTRACT

A novel papillomavirus (PV) associated with hyperplastic nodules scattered over the muco-cutaneous border of the oral cavity of a dead, wild, subadult northern sea otter Enhydra lutris kenyoni (NSO) in 2004 in Homer, Alaska, USA, was genetically characterized. Primers for the amplification of 2 large overlapping DNA fragments that contained the complete genome of the NSO PV were designed. Sanger methodology generated sequences from which new specific primers were designed for the primer-walking approach. The NSO PV genome consists of 8085 nucleotides and contains an early region composed of E6, E7, E1, and E2 open reading frames (ORFs), an E4 ORF (contained within E2) lacking an in-frame proximal ATG start codon, an unusually long (907 nucleotide) stretch lacking any ORFs, a late region that contains the capsid genes L2 and L1, and a non-coding regulatory region (ncRR). This NSO PV has been tentatively named Enhydra lutris kenyoni PV2 (ElkPV2). Pairwise and multiple sequence alignments of the complete L1 ORF nucleotides and concatenated E1-E2-L1 amino acid sequences showed that the NSO PV is a novel PV, phylogenetically most closely related to southern sea otter PV1. The carboxy end of the E6 oncoprotein does not contain the PDZ-binding motif with a strong correlation with oncogenicity, suggesting a low-risk PV, which is in agreement with histopathological findings. However, the ElkPV2 E7 oncoprotein does contain the retinoblastoma (pRb) binding domain LXCXE (LQCYE in ElkPV2), associated with oncogenicity in some high-risk PVs. Further studies on the prevalence and clinical significance of ElkPV2 infections in NSO are needed.


Subject(s)
Lambdapapillomavirus , Otters , Animals , Alaska/epidemiology , Nucleotides , Oncogene Proteins
16.
Sci Rep ; 14(1): 1226, 2024 01 12.
Article in English | MEDLINE | ID: mdl-38216624

ABSTRACT

Although the ecological network approach has substantially contributed to the study of plant-pollinator interactions, current understanding of their functional structure is biased towards diurnal pollinators. Nocturnal pollinators have been systematically ignored despite the publication of several studies that have tried to alleviate this diurnal bias. Here, we explored whether adding this neglected group of pollinators had a relevant effect on the overall architecture of three high mountain plant-pollinator networks. Including nocturnal moth pollinators modified network properties by decreasing total connectivity, connectance, nestedness and robustness to plant extinction; and increasing web asymmetry and modularity. Nocturnal moths were not preferentially connected to the most linked plants of the networks, and they were grouped into a specific "night" module in only one of the three networks. Our results indicate that ignoring the nocturnal component of plant-pollinator networks may cause changes in network properties different from those expected from random undersampling of diurnal pollinators. Consequently, the neglect of nocturnal interactions may provide a distorted view of the structure of plant-pollinator networks with relevant implications for conservation assessments.


Subject(s)
Moths , Pollination , Animals , Plants , Insecta
17.
J Vasc Surg Venous Lymphat Disord ; 12(3): 101817, 2024 May.
Article in English | MEDLINE | ID: mdl-38296110

ABSTRACT

OBJECTIVE: The aim of this study was to assess race and sex disparities in use and outcomes of various interventions in patient with acute pulmonary embolism (PE). METHODS: We included 129,445 patients with acute PE from the NIS from January 2016 to December 2019. Rates of inferior vena cava (IVC) filter placement, catheter-directed thrombolysis (CDT), CDT with ultrasound, systemic thrombolysis, surgical embolectomy, percutaneous thrombectomy, extracorporeal membrane oxygenation, and mechanical ventilation were compared between race and sex subgroups, along with length of hospital stay, major bleeding events, mortality, and other adverse events. Multivariate linear regression analysis was used to adjust for variables that were significantly different between race and sex, including demographic factors, comorbidities, socioeconomic factors, and hospital characteristics. RESULTS: Compared with White male patients, all subgroups had significantly higher odds of in-hospital mortality highest in Hispanic male patients (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.090-1.640; P < .01). All subgroups also had a higher odds of major bleeding events and increased length of stay. All subgroups also had lower odds of receiving CDT, lowest in Black female patients (OR, 0.740; 95% CI, 0.660-0.820; P < .001) and Hispanic female patients (0.780; 95% CI, 0.650-0.940; P < .001) compared with White male patients. There was no significant difference in the use of systemic thrombolysis among subgroups. CONCLUSIONS: Black and Hispanic patients and female patients are less likely to undergo CDT compared with White male patients, in addition to having higher odds of mortality, major bleeding, and increased length of stay after management of PE. Further efforts are needed to mitigate disparate outcomes of PE management at not only an institutional, but at a national, level to promote health care equality.


Subject(s)
Pulmonary Embolism , Thrombolytic Therapy , Humans , Male , Female , Thrombolytic Therapy/adverse effects , Health Promotion , Pulmonary Embolism/etiology , Thrombectomy/adverse effects , Hemorrhage/etiology , Acute Disease , Treatment Outcome , Retrospective Studies
18.
J Vasc Surg Venous Lymphat Disord ; 12(1): 101683, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37708935

ABSTRACT

OBJECTIVE: We sought to determine whether racial and ethnic disparities existed in inferior vena cava (IVC) filter (IVCF) placement rates among Black and Latino patients for the treatment of acute proximal lower extremity (LE) deep vein thrombosis (DVT) in the United States from 2016 to 2019. METHODS: We performed a retrospective review of National Inpatient Sample data to identify adult patients with a primary discharge diagnosis of acute proximal LE DVT from January 2016 to December 2019, including self-reported patient race and ethnicity. IVCF placement rates were identified using International Classification of Diseases, 10th revision, codes. Weighted multivariable logistic regression was used to compare IVCF use by race and ethnicity. The regression model was adjusted for patient demographics (ie, sex, primary payer, quartile classification of household income), hospital information (ie, region, location, teaching status, bed size), weekend admission, and clinical characteristics (ie, modified Charlson comorbidity index, hypertension, atrial fibrillation, diabetes mellitus type 2, congestive heart failure, dyslipidemia, coronary artery disease, smoking, obesity, alcohol abuse, chronic kidney disease, pulmonary embolism, malignancy, contraindications to anticoagulation, including other major bleeding). RESULTS: Of 134,499 acute proximal LE DVT patients, 18,909 (14.1%) received an IVCF. Of the patients who received an IVCF, 12,733 were White (67.3%), 3563 were Black (18.8%), and 1679 were Latino (8.9%). IVCF placement decreased for all patient groups between 2016 and 2019. After adjusting for the U.S. population distribution, the IVCF placement rates were 11 to 12/100,000 persons for Black patients, 7 to 8/100,000 persons for White patients, and 4 to 5/100,000 persons for Latino patients. The difference in IVCF placement rates was statistically significant between patient groups (Black patients vs White patients, P < .05; Black patients vs Latino patients, P < .05; Latino patients vs White patients, P < .05). CONCLUSIONS: This nationwide study showed that Black patients have higher IVCF placement rates compared with White and Latino patients. Given the known long-term complications and uncertain benefits of IVCFs, coupled with the 2010 U.S. Food and Drug Administration safety warning regarding adverse patient events for these devices, proactive measures should be taken to address this disparity among the Black patient population to promote health equity. Future work should assess whether clinician bias might be perpetuating this disparity.


Subject(s)
Pulmonary Embolism , Vena Cava Filters , Venous Thrombosis , Adult , Humans , United States , Vena Cava Filters/adverse effects , Health Promotion , Treatment Outcome , Venous Thrombosis/diagnostic imaging , Venous Thrombosis/therapy , Venous Thrombosis/complications , Pulmonary Embolism/etiology , Retrospective Studies , Vena Cava, Inferior
19.
ACS Omega ; 8(47): 44920-44930, 2023 Nov 28.
Article in English | MEDLINE | ID: mdl-38046348

ABSTRACT

A parabolic trough collector solar field was designed to supply the heat needed to regenerate the CO2-rich monoethanolamine in a solar-assisted carbon capture system. Process design modeling was performed for 90% of the CO2 removal from 1% of the flue gas produced by a 255 MWe natural gas combined cycle power plant. Calculations with and without 24 h of thermal energy storage by increasing the solar collector size needed and providing a buffer vessel to store hot heat transfer fluid were performed. A dynamic analysis of the solar field using the hourly solar forecast was performed to investigate how heat transfer fluid mass flow changes during January and June to maintain the desired parabolic solar field outlet temperature needed for CO2 reboiler operation. The calculations provided here present an explicit method to calculate relevant solar field design parameters that can be scaled up and used in solar energy-assisted gas capture processes.

20.
Materials (Basel) ; 16(23)2023 Nov 24.
Article in English | MEDLINE | ID: mdl-38068072

ABSTRACT

This work is dedicated to the study of the effect of the synthesis conditions (drying and calcination) of sulfated zirconia on the final catalytic behavior of bifunctional composite catalysts prepared by the physical mixing of the sulfated zirconia (methanol dehydration catalyst) with Cu/ZnO/Al2O3 (CZA; methanol synthesis catalyst). The main objective was to optimize the CZA-ZrO2/SO42- composite catalyst for its use in the direct production of dimethyl ether (DME) from syngas. Sulfated zirconia aerogel (AZS) and xerogel (XZS) were prepared using the sol-gel method using different solvent evacuation conditions and calcination temperatures, while the Cu-ZnO(Al) catalyst was synthesized using the coprecipitation procedure. The effectivity of CZA-ZrO2/SO42- composite catalysts for the direct production of dimethyl ether (DME) from syngas was evaluated in a flow reactor at 250 °C and 30 bar total pressure. The characterization of the sulfated zirconia aerogels and xerogels using different techniques showed that the mesoporous aerogel (AZS0.5300) exhibited the best textural and acidic properties due to the gel drying under supercritical conditions and calcination at 300 °C. As a result, the composite catalyst CZA-AZS0.5300 exhibited seven times higher DME production than its xerogel-containing counterpart (364 vs. 52 µmolDME·min-1·gcat-1). This was attributed to its well-matched metal surface, mesoporous structure, optimal crystallite size and, most importantly, its higher acidity.

SELECTION OF CITATIONS
SEARCH DETAIL
...