Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.151
Filtrar
1.
J Environ Sci (China) ; 148: 451-467, 2025 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-39095179

RESUMEN

After the ultralow emission transformation of coal-fired power plants, cement production became China's leading industrial emission source of nitrogen oxides. Flue gas dust contents at the outlet of cement kiln preheaters were as high as 80-100 g/m3, and the calcium oxide content in the dust exceeded 60%. Commercial V2O5(-WO3)/TiO2 catalysts suitable for coal-fired flue gas suffer from alkaline earth metal Ca poisoning of cement kiln flue gas. Recent studies have also identified the poisoning of cement kiln selective catalytic reaction (SCR) catalysts by the heavy metals lead and thallium. Investigation of the poisoning process is the primary basis for analyzing the catalytic lifetime. This review summarizes and analyzes the SCR catalytic mechanism and chronicles the research progress concerning this poisoning mechanism. Based on the catalytic and toxification mechanisms, it can be inferred that improving the anti-poisoning performance of a catalyst enhances its acidity, surface redox performance-active catalytic sites, and shell layer protection. The data provide support in guiding engineering practice and reducing operating costs of SCR plants. Finally, future research directions for SCR denitrification catalysts in the cement industry are discussed. This study provides critical support for the development and optimization of poisoning-resistant SCR denitrification catalysts.


Asunto(s)
Materiales de Construcción , Catálisis , Contaminantes Atmosféricos/química , Centrales Eléctricas , China
2.
J Environ Sci (China) ; 150: 332-339, 2025 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-39306408

RESUMEN

NH3-SCR (SCR: Selective catalytic reduction) is an effective technology for the de-NOx process from both mobile and stationary pollution sources, and the most commonly used catalysts are the vanadia-based catalysts. An innovative V2O5-CeO2/TaTiOx catalyst for NOx removal was prepared in this study. The influences of Ce and Ta in the V2O5-CeO2/TaTiOx catalyst on the SCR performance and physicochemical properties were investigated. The V2O5-CeO2/TaTiOx catalyst not only exhibited excellent SCR activity in a wide temperature window, but also presented strong resistance to H2O and SO2 at 275 ℃. A series of characterization methods was used to study the catalysts, including H2-temperature programmed reduction, X-ray photoelectron spectroscopy, NH3-temperature programmed desorption, etc. It was discovered that a synergistic effect existed between Ce and Ta species. The introduction of Ce and Ta enlarged the specific surface area, increased the amount of acid sites and the ratio of Ce3+, (V3++V4+) and Oα, and strengthened the redox capability which were related to synergistic effect between Ce and Ta species, significantly improving the NH3-SCR activity.


Asunto(s)
Amoníaco , Cerio , Titanio , Compuestos de Vanadio , Catálisis , Cerio/química , Titanio/química , Amoníaco/química , Compuestos de Vanadio/química , Contaminantes Atmosféricos/química , Oxidación-Reducción , Contaminación del Aire/prevención & control
3.
J Environ Sci (China) ; 150: 451-465, 2025 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-39306420

RESUMEN

Nitrogen oxides (NOx) from diesel engine exhaust, is one of the major sources of environmental pollution. Currently, selective catalytic reduction with ammonia (NH3-SCR) is considered to be the most effective protocol for reducing NOx emissions. Nowadays, zeolite-based NH3-SCR catalysts have been industrialized and widespread used in this field. Nevertheless, with the increasingly stringent environmental regulations and implementation of the requirement of "zero emission" of diesel engine exhaust, it is extremely urgent to prepare catalysts with superior NH3-SCR activity and exceptional resistance to poisons (SO2, alkali metals, hydrocarbons, etc.). Core-shell structure zeolite-based catalysts (CSCs) have shown great promise in NH3-SCR of NOx in recent years by virtue of its relatively higher low-temperature activity, broader operation temperature window and outstanding resistance to poisons. This review mainly focuses on the recent progress of CSCs for NH3-SCR of NOx with three extensively investigated SSZ-13, ZSM-5, Beta zeolites as cores. The reaction mechanisms of resistance to sulfur poisoning, alkali metal poisoning, hydrocarbon poisoning, and hydrothermal aging are summarized. Moreover, the important role of interfacial effect between core and shell in the reaction of NH3-SCR was clarified. Finally, the future development and application outlook of CSCs are prospected.


Asunto(s)
Contaminantes Atmosféricos , Óxidos de Nitrógeno , Emisiones de Vehículos , Zeolitas , Zeolitas/química , Óxidos de Nitrógeno/química , Catálisis , Contaminantes Atmosféricos/química , Emisiones de Vehículos/análisis , Contaminación del Aire/prevención & control , Amoníaco/química
4.
Front Med Technol ; 6: 1413637, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39355139

RESUMEN

Celiac disease is an autoimmune enteropathy caused by the ingestion of minute amounts of gluten in a subset of genetically predisposed individuals. Its onset occurs at different ages and with variable symptoms. The gut microbiome may contribute to this variability. This review aims to provide an overview of the available research on celiac disease gut microbiome and identify the knowledge gap that could guide future studies. Following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis extension for Scoping Reviews (PRISMA-ScR), four electronic databases were searched for literature from January 2000 to July 2023 addressing celiac disease gut microbiome characterization using next-generation sequencing (NGS) approaches. From the 489 publications retrieved, 48 publications were selected and analyzed, focusing on sample characterization (patients, controls, and tissues) and methodologies used for NGS microbiome analysis and characterization. The majority of the selected publications regarded children and adults, and four were randomized clinical trials. The number of participants per study greatly varied and was typically low. Feces were the most frequently tested sample matrix, and duodenal samples were analyzed in one-third of the studies. Incomplete and diverse information on the methodological approaches and gut microbiome results was broadly observed. While similar trends regarding the relative abundance of some phyla, such as Pseudomonadota (former Proteobacteria), were detected in some studies, others contradicted those results. The observed high variability of technical approaches and possibly low power and sample sizes may prevent reaching a consensus on celiac disease gut microbiome composition. Standardization of research protocols to allow reproducibility and comparability is required, as interdisciplinary collaborations to further data analysis, interpretation, and, more importantly, health outcome prediction or improvement.

5.
J Colloid Interface Sci ; 679(Pt A): 634-652, 2024 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-39388950

RESUMEN

In the selective catalytic reduction of NOx by NH3 (NH3-SCR), conventional Mn-based denitration catalysts often suffered from susceptibility to poisoning by alkali and alkaline earth metals, this paper presented an innovative self-protected Chlorella@Mn denitration catalyst. Remarkably, in the presence of high concentrations (2 wt%) of alkali and alkaline earth metal oxides, the Chlorella@Mn catalyst sustained a NOx conversion exceeding 96 % at 175 °C. At an even higher concentration (4 wt%), NOx conversion above 90 % at 175 °C, surface analysis revealed that POMn sites acted as sacrificial sites, binding to the alkali and alkaline earth metals, the Chlorella@Mn catalyst surface naturally carried a spectrum of acidic species (such as SO42-, PO3-, SiO32-), proficient in capturing alkali/alkaline earth metal effectively, elements such as S, P, and Si formed bonds with K, Na, Ca, and Mg. The synergistic protection of the active sites and the surface elements avoided the deactivation of the catalyst. The detrimental effects of high concentrations of alkali and alkaline earth metals were primarily due to promoting an excessively high valence state of Mn on the catalyst surface and the reduction or loss of NH3 adsorption and activation at Brønsted acid sites. This research provided valuable insights for advancing the development of low-temperature denitration catalysts with improved resistance to alkali and alkaline earth metal poisoning.

6.
Psychophysiology ; : e14701, 2024 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-39392401

RESUMEN

Concealed information test (CIT) has been utilized for long to perform single measurements. The combination of multiple measures outperforms single measures because of the diverse cognitive processes they reflect and the reduction in random errors facilitated by multiple measures. To further explore the performance of the CIT with multiple measurements, 57 participants were recruited and randomly assigned into guilty and innocent groups. Subsequently, simultaneously recorded reaction time (RT), skin conductance responses (SCRs), heart rate (HR), and neuroimaging data were collected from functional near-infrared spectroscopy (fNIRS) to detect participants' concealed information in a standard CIT. The results demonstrated that all indicators including RT (area under the curve (AUC) = 0.87), SCRs (AUC = 0.79), HR (AUC = 0.78), and fNIRS (channel 8, AUC = 0.85) could differentiate guilty and innocent groups. Importantly, the use of multiple indicators achieved higher detection efficiency (AUC = 0.96) compared to the use of any single indicator. These results illustrate the effectiveness and feasibility of integrating multiple indicators for concealed information detection in CIT.

7.
J Hazard Mater ; 480: 136112, 2024 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-39405672

RESUMEN

V2O5-WO3/TiO2 (VWTi) catalyst has long been utilized in fixed source flue gases to purify harmful NO gas. However, VWTi is classified as a hazardous material because of its harm to human health and environment. To address this issue, a low-cost green Cu-based zeolite catalyst (Cu@13X) with a wide temperature range was synthesized using an in-situ hydrothermal method. This method is intended to control the adsorption capacity of toxic SO2 by regulating the location of Cu species. UV-Vis DRS and EXAFS analyses revealed that a significant amount of Cu was encapsulated within the 12-membered ring pores of the 13X molecular sieve. SO2-TPD and DFT calculations further indicated that Cu@ 13X exhibits reduced SO2 chemical adsorption capacity. Consequently, this green catalyst demonstrated superior catalytic performance, maintaining superior NOx conversion for over 70 h in the mixture gas containing 250 ppm SO2; while the Cu/13X catalyst lacked NH3-SCR catalytic activity under the same conditions. Moreover, Cu@ 13X catalyst also has excellent NH3-SCR catalytic performance in low temperature flue gas below 250 °C, which is significantly better than the hazardous VWTi catalyst. Characterization techniques such as NH3-TPD, H2-TPR, and XPS confirmed that the Cu@ 13X catalyst possesses excellent acidity, robust redox capabilities, and abundant surface defects. In-situ DRIFT spectra further illustrated that the NH3-SCR reaction on the catalyst surface adheres to the Eley-Rideal mechanism both before and after the introduction of toxic SO2. This study offers a fresh perspective on the development of framework-confined NH3-SCR catalysts and elucidates the mechanism behind the sulfur resistance of these catalysts. And the green Cu@ 13X catalyst is anticipated to serve as an effective alternative to the hazardous VWTi catalyst.

8.
Brain Behav ; 14(10): e70089, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39378296

RESUMEN

INTRODUCTION: We developed a low-cost, user-friendly complementary research tool to evaluate autonomic nervous system (ANS) activity at varying levels of cognitive workload. This was achieved using visual stimuli as cognitive tasks, administered through a specially designed computer-based test battery. METHODS: To assess sympathetic stress responses, skin conductance response (SCR) was measured, and electrocardiograms (ECG) were recorded to evaluate heart rate variability (HRV), an indicator of cardiac vagal tone. Twenty-five healthy adults participated in the study. SCR and ECG recordings were made during both tonic and phasic phases using a computer-based system designed for visual stimuli. Participants performed a button-pressing task upon seeing the target stimulus, and the relationship between reaction time (RT) and cognitive load was evaluated. RESULTS: Analysis of the data showed higher skin conductance levels (SCLs) during tasks compared to baseline, indicating successful elicitation of sympathetic responses. RTs differed significantly between simple and cognitive tasks, increasing with mental load. Additionally, significant changes in vagally mediated HRV parameters during tasks compared to baseline highlighted the impact of cognitive load on the parasympathetic branch of the ANS, thereby influencing the brain-heart connection. CONCLUSION: Our findings indicate that the developed research tool can successfully induce cognitive load, significantly affecting SCL, RTs, and HRV. This validates the tool's effectiveness in evaluating ANS responses to cognitive tasks.


Asunto(s)
Sistema Nervioso Autónomo , Cognición , Electrocardiografía , Respuesta Galvánica de la Piel , Frecuencia Cardíaca , Tiempo de Reacción , Humanos , Masculino , Femenino , Frecuencia Cardíaca/fisiología , Adulto , Respuesta Galvánica de la Piel/fisiología , Cognición/fisiología , Sistema Nervioso Autónomo/fisiología , Adulto Joven , Tiempo de Reacción/fisiología , Desempeño Psicomotor/fisiología
9.
JMIR Med Inform ; 12: e49781, 2024 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-39401130

RESUMEN

Background: Electronic medical records (EMRs) contain large amounts of detailed clinical information. Using medical record review to identify conditions within large quantities of EMRs can be time-consuming and inefficient. EMR-based phenotyping using machine learning and natural language processing algorithms is a continually developing area of study that holds potential for numerous mental health disorders. Objective: This review evaluates the current state of EMR-based case identification for depression and provides guidance on using current algorithms and constructing new ones. Methods: A scoping review of EMR-based algorithms for phenotyping depression was completed. This research encompassed studies published from January 2000 to May 2023. The search involved 3 databases: Embase, MEDLINE, and APA PsycInfo. This was carried out using selected keywords that fell into 3 categories: terms connected with EMRs, terms connected to case identification, and terms pertaining to depression. This study adhered to the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines. Results: A total of 20 papers were assessed and summarized in the review. Most of these studies were undertaken in the United States, accounting for 75% (15/20). The United Kingdom and Spain followed this, accounting for 15% (3/20) and 10% (2/20) of the studies, respectively. Both data-driven and clinical rule-based methodologies were identified. The development of EMR-based phenotypes and algorithms indicates the data accessibility permitted by each health system, which led to varying performance levels among different algorithms. Conclusions: Better use of structured and unstructured EMR components through techniques such as machine learning and natural language processing has the potential to improve depression phenotyping. However, more validation must be carried out to have confidence in depression case identification algorithms in general.


Asunto(s)
Algoritmos , Depresión , Registros Electrónicos de Salud , Procesamiento de Lenguaje Natural , Humanos , Depresión/diagnóstico , Depresión/epidemiología , Aprendizaje Automático , Pacientes Internos/psicología , Fenotipo
10.
J Comp Neurol ; 532(10): e25675, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39387367

RESUMEN

Highly sensitive in situ hybridization procedures (RNAScope) were used to quantify the expression of three dopamine receptors (Drd1, Drd2, and Drd3) in two song control nuclei (HVC and the Area X of the basal ganglia) that are known to receive dopaminergic inputs and in the periaqueductal gray (PAG) of male and female canaries. Both sexes were treated with testosterone to ensure they would sing actively. We also determined the excitatory versus inhibitory phenotype of the cells expressing these receptors as well as their activation following a period of song production. The three receptor types were identified in each brain area, with the exception of Drd3 in Area X. The density of cells expressing each receptor varied as a function of receptor type and brain area. Surprisingly few sex differences were detected; they do not seem to explain the sex differences in testosterone-induced song. Overall, the density of Drd-positive cells was much lower in PAG than in the two song control nuclei. In HVC, the majority of cells expressing the three receptor subtypes were VGlut2-positive, whereas colocalization with Vglut2 occurred in few cells in Area X and in an intermediate proportion of cells in PAG. The number of inhibitory cells expressing dopamine receptors was limited. Most dopaminoceptive cells in Area X did not express either excitatory or inhibitory markers. Finally, cellular activation during singing behavior, as measured by the expression of Egr1, was observed in cells expressing each of the three dopamine receptor subtypes, except Drd3 in the PAG.


Asunto(s)
Canarios , Hibridación Fluorescente in Situ , Vocalización Animal , Animales , Masculino , Femenino , Vocalización Animal/fisiología , Vocalización Animal/efectos de los fármacos , Canarios/fisiología , Hibridación Fluorescente in Situ/métodos , Receptores Dopaminérgicos/metabolismo , Caracteres Sexuales , Testosterona/metabolismo , Sustancia Gris Periacueductal/metabolismo
11.
Environ Sci Technol ; 2024 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-39387477

RESUMEN

Ceria with surface solid frustrated Lewis pairs (FLPs), formed by regulating oxygen vacancies, demonstrate remarkable ability in activating small molecules. In this work, we extended the application of FLPs on CeO2(110) to the selective catalytic reduction of NO by NH3 (NH3-SCR), finding a notable enhancement in performance compared to ordinary CeO2(110). Additionally, an innovative approach involving H2 treatment was discovered to increase the number of FLPs, thereby further boosting the NH3-SCR efficiency. Typically, NH3-SCR on regular CeO2 follows the Eley-Rideal (E-R) mechanism. However, density functional theory (DFT) calculations revealed a significant reduction in the energy barriers for the activation of N-O and N-H bonds under the Langmuir-Hinshelwood (L-H) mechanism with FLPs present. This transition shifted the reaction mechanism from the E-R pathway on regular R-CeO2 to the L-H pathway on FLP-rich FR-CeO2, as corroborated by the experimental findings. The practical application of FLPs was realized by loading MoO3 onto FLP-rich FR-CeO2, leveraging the synergistic effects of acidic sites and FLPs. This study provides profound insights into how FLPs facilitate N-H/N-O bond activation in small molecules, such as NH3 and NO, offering a new paradigm for catalyst design based on catalytic mechanism research.

12.
Molecules ; 29(18)2024 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-39339501

RESUMEN

Selective catalytic reduction of nitrogen oxides (NOx) with ammonia (NH3-SCR) has been implemented in response to the regulation of NOx emissions from stationary and mobile sources above 300 °C. However, the development of NH3-SCR catalysts active at low temperatures below 200 °C is still needed to improve the energy efficiency and to cope with various fuels. In this review article, recent reports on low-temperature NH3-SCR catalysts are systematically summarized. The redox property as well as the surface acidity are two main factors that affect the catalytic activity. The strong redox property is beneficial for the low-temperature NH3-SCR activity but is responsible for N2O formation. The multiple electron transfer system is more plausible for controlling redox properties. H2O and SOx, which are often found with NOx in flue gas, have a detrimental effect on NH3-SCR activity, especially at low temperatures. The competitive adsorption of H2O can be minimized by enhancing the hydrophobic property of the catalyst. Various strategies to improve the resistance to SOx poisoning are also discussed.

13.
Chem Asian J ; : e202400802, 2024 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-39240103

RESUMEN

The technology of CO selective catalytic reduction of NOx (CO-SCR) showcases the potential to simultaneously eliminate CO and NOx from industrial flue gas and automobile exhaust, making it a promising denitrification method. The development of cost-effective catalysts is crucial for the widespread implementation of this technology. Transition metal catalysts are more economically viable than noble metal catalysts. Among these, Fe emerges as a prominent choice due to its abundant availability and cost-effectiveness, exhibiting excellent catalytic performance at moderate reaction temperatures. However, a significant challenge lies in achieving high catalytic activity at low temperatures, particularly in the presence of O2, SO2, and H2O, which are prevalent in specific industrial flue gas streams. This review examines the use of Fe-based catalysts in the CO-SCR reaction and elucidates their catalytic mechanism. Furthermore, it also discusses various strategies devised to enhance low-temperature conversion, taking into account factors such as crystal phase, valence states, and oxygen vacancies. Subsequently, the review outlines the challenges encountered by Fe-based catalysts and offers recommendations to improve their catalytic efficiency for use in low-temperature and oxygen-rich environments.

14.
Environ Sci Technol ; 2024 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-39250812

RESUMEN

Water is ubiquitous in various heterogeneous catalytic reactions, where it can be easily adsorbed, chemically dissociated, and diffused on catalyst surfaces, inevitably influencing the catalytic process. However, the specific role of water in these reactions remains unclear. In this study, we innovatively propose that H2O-driven surface lattice oxygen activation in γ-MnO2 significantly enhances low-temperature NH3-SCR. The proton from water dissociation activates the surface lattice oxygen in γ-MnO2, giving rise to a doubling of catalytic activity (achieving 90% NO conversion at 100 °C) and remarkable stability. Comprehensive in situ characterizations and calculations reveal that spontaneous proton diffusion to the surface lattice oxygen reduces the orbital overlap between the protonated oxygen atom and its neighboring Mn atom. Consequently, the Mn-O bond is weakened and the surface lattice oxygen is effectively activated to provide excess oxygen vacancies available for converting O2 into O2-. Therefore, the redox property of Mn-H is improved, leading to enhanced NH3 oxidation-dehydrogenation and NO oxidation processes, which are crucial for low-temperature NH3-SCR. This work provides a deeper understanding and fresh perspectives on the water promotion mechanism in low-temperature NOx elimination.

15.
Environ Sci Technol ; 2024 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-39292987

RESUMEN

The presence of light hydrocarbons (HCs) in diesel exhaust, specifically C3H6, significantly affects the performance of the state-of-the-art Cu-SSZ-13 zeolite NH3-SCR catalysts. It also leads to the formation of highly toxic HCN, posing risks to the environment and human health. In this work, the highly toxic HCN formation is inhibited, and the C3H6 resistance of Cu-SSZ-13 is improved by secondary metal modification via doping with rare earth/transition metal elements. Upon introduction of C3H6, the activity of Cu-SSZ-13 significantly decreases at medium-high temperatures. This is primarily due to the competitive reaction between C3H6 and NH3, which compete for the NH3 reductant required in the NH3-SCR reaction, resulting in the production of HCN. The unfavorable effect is alleviated on the modified catalysts due to their enhanced oxidation capabilities toward C3H6 and the HCHO intermediate, facilitating the complete oxidation of C3H6 to COx. This inhibits the undesirable partial oxidation reaction between C3H6 and NH3, thereby improving the activity of Cu-SSZ-13 at medium to high temperatures and significantly reducing the formation of highly toxic HCN.

16.
J Neurosci Res ; 102(9): e25377, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39275861

RESUMEN

Individuals considered resilient can overcome adversity, achieving normal physical and psychological development, while those deemed vulnerable may not. Adversity promotes structural and functional alterations in the medial prefrontal cortex (mPFC) and hippocampus. Moreover, activity-dependent synaptic plasticity is intricately linked to neuronal shaping resulting from experiences. We hypothesize that this plasticity plays a crucial role in resilience processes. However, there is a notable absence of studies investigating this plasticity and behavioral changes following social adversity at different life stages. Consequently, we evaluated the impact of social adversity during early postnatal development (maternal separation [MS]), adulthood (social defeat [SD]), and a combined exposure (MS + SD) on behavioral outcomes (anxiety, motivation, anhedonia, and social interaction). We also examined cFos expression induced by social interaction in mPFC and hippocampus of adult male rats. Behavioral analyses revealed that SD-induced anhedonia, whereas MS + SD increased social interaction and mitigated SD-induced anhedonia. cFos evaluation showed that social interaction heightened plasticity in the prelimbic (PrL) and infralimbic (IL) cortices, dentate gyrus (DG), CA3, and CA1. Social interaction-associated plasticity was compromised in IL and PrL cortices of the MS and SD groups. Interestingly, social interaction-induced plasticity was restored in the MS + SD group. Furthermore, plasticity was impaired in DG by all social stressors, and in CA3 was impaired by SD. Our findings suggest in male rats (i) two adverse social experiences during development foster resilience; (ii) activity-dependent plasticity in the mPFC is a foundation for resilience to social adversity; (iii) plasticity in DG is highly susceptible to social adversity.


Asunto(s)
Privación Materna , Plasticidad Neuronal , Corteza Prefrontal , Resiliencia Psicológica , Animales , Plasticidad Neuronal/fisiología , Masculino , Ratas , Anhedonia/fisiología , Interacción Social , Derrota Social , Hipocampo , Estrés Psicológico/fisiopatología , Estrés Psicológico/psicología , Ratas Wistar , Conducta Animal/fisiología , Conducta Social , Ansiedad/fisiopatología
17.
J Comp Neurol ; 532(9): e25669, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39291629

RESUMEN

The cerebral cortex accounts for substantial energy expenditure, primarily driven by the metabolic demands of synaptic signaling. Mitochondria, the organelles responsible for generating cellular energy, play a crucial role in this process. We investigated ultrastructural characteristics of the primary visual cortex in 18 phylogenetically diverse mammals, spanning a broad range of brain sizes from mouse to elephant. Our findings reveal remarkable uniformity in synapse density, postsynaptic density (PSD) length, and mitochondria density, indicating functional and metabolic constraints that maintain these fundamental features. Notably, we observed an average of 1.9 mitochondria per synapse across mammalian species. When considered together with the trend of decreasing neuron density with larger brain size, we find that brain enlargement in mammals is characterized by increasing proportions of synapses and mitochondria per cortical neuron. These results shed light on the adaptive mechanisms and metabolic dynamics that govern cortical ultrastructure across mammals.


Asunto(s)
Mamíferos , Mitocondrias , Corteza Visual Primaria , Sinapsis , Animales , Sinapsis/ultraestructura , Sinapsis/metabolismo , Mitocondrias/ultraestructura , Mitocondrias/metabolismo , Corteza Visual Primaria/fisiología , Metabolismo Energético/fisiología , Especificidad de la Especie , Corteza Visual/metabolismo , Corteza Visual/citología , Corteza Visual/fisiología , Corteza Visual/ultraestructura , Ratones , Humanos
18.
Heliyon ; 10(18): e37684, 2024 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-39315173

RESUMEN

Currently generated nitrogen oxides (NOx) and unburned ammonia (NH3) can be converted into nitrogen and moisture that are harmless to the human body and environment using selective catalytic reduction (SCR). The concentrations of NOx and unburned NH3 emitted from the ammonia combustion engines are significantly higher than those emitted by engines using existing hydrocarbon fuels. In this study, ammonia, a representative carbon-free fuel, was used in spark ignition engines for existing passenger vehicles to identify the trends in exhaust gases emitted from engines and conduct experiments on after-treatment strategies to reduce NOx and unburned NH3. The addition of oxygen significantly maximized the conversion efficiency of the SCR after-treatment system by changing the concentration of both NOx and NH3 in the exhaust gas.

19.
Molecules ; 29(16)2024 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-39202827

RESUMEN

Zeolite-based catalysts efficiently catalyze the selective catalytic reduction of NOx with methane (CH4-SCR) for the environmentally friendly removal of nitrogen oxides, but suffer severe deactivation in high-temperature SO2- and H2O-containing flue gas. In this work, SSZ-39 zeolite (AEI topology) with high hydrothermal stability is reported for preparing CH4-SCR catalysts. Mild acid leaching with oxalic acid (OA) not only modulates the Si/Al ratio of commercial SSZ-39 to a suitable value, but also removes some extra-framework Al atoms, introducing a small number of mesopores into the zeolite that alleviate diffusion limitation. Additional Co3O4 modification during indium exchange further enhances the catalytic activity of the resulting In-Co3O4/H-SSZ-39(OA). The optimized sample exhibits remarkable performance in CH4-SCR under a gas hourly space velocity (GHSV) of 24,000 h-1 and in the presence of 5 vol% H2O. Even under harsh SO2- and H2O-containing high-temperature conditions, it shows satisfactory stability. Catalysts containing Co3O4 components demonstrate much higher CH4 conversion. The strong mutual interaction between Co3O4 and Brønsted acid sites, confirmed by the temperature-programmed desorption of NO (NO-TPD), enables more stable NxOy species to be retained in In-Co3O4/H-SSZ-39(OA) to supply further reactions at high temperatures.

20.
J Clin Med ; 13(16)2024 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-39200788

RESUMEN

Objectives: The purpose of the present study was to evaluate clinical and functional outcomes, graft integrity rate and progression of osteoarthritis after superior capsular reconstruction (SCR) at short-term follow-up. Methods: Consecutive patients that underwent SCR using an acellular dermal xeno- or allograft between May 2018 and June 2020 for the treatment of irreparable posterosuperior rotator cuff tears were included. Shoulder function (American Shoulder and Elbow Surgeons [ASES] score), pain (Visual Analog Scale [VAS] for pain) and active shoulder range of motion (ROM) were evaluated preoperatively and after a minimum of 24 months postoperatively. Isometric strength was measured at follow-up and compared to the contralateral side. Magnetic resonance imaging was performed to evaluate graft integrity and osteoarthritis progression (shoulder osteoarthritis severity [SOAS] score). Results: Twenty-two patients that underwent SCR using a xeno- (n = 9) or allograft (n = 13) were evaluated 33.1 ± 7.2 months postoperatively. Four patients in the xenograft group underwent revision surgery due to pain and range of motion limitations and were excluded from further analysis (revision rate: 18.2%). Shoulder function (ASES score: 41.6 ± 18.8 to 72.9 ± 18.6, p < 0.001), pain levels (VAS for pain: 5.8 ± 2.5 to 1.8 ± 2.0, p < 0.001) and active flexion (p < 0.001) as well as abduction ROM (p < 0.001) improved significantly from pre- to postoperatively. Active external rotation ROM did not improve significantly (p = 0.924). Isometric flexion (p < 0.001), abduction (p < 0.001) and external rotation strength (p = 0.015) were significantly lower in the operated shoulder compared to the non-operated shoulder. Ten shoulders demonstrated a graft tear at the glenoid (n = 8, 44.4%) or humerus (n = 2, 11.1%). Graft lysis was observed in seven shoulders (38.9%). The graft was intact in one shoulder (5.6%), which was an allograft. A significant progression of shoulder osteoarthritis was observed at follow-up (SOAS score: 42.4 ± 10.1 to 54.6 ± 8.4, p < 0.001). Conclusions: At short-term follow-up, SCR using an acellular dermal xeno- or allograft resulted in improved shoulder function and pain with limitations in active external rotation ROM and isometric strength. Graft failure rates were high and osteoarthritis progressed significantly. Level of Evidence: Retrospective cohort study, Level III.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...