The thermo-catalytic hydrogenation of greenhouse gas CO2 into more valuable products, primarily fuels such as methane and alcohols, is a promising pathway of carbon utilization. Since CO2 is known for its inertness with high activation energy, which makes it difficult to activate for the hydrogenation reaction, thus demanding higher temperatures for its conversion to useful products. Widespread efforts have been made to optimize catalysts for better catalytic performance at less severe operating conditions. This has garnered research community interest in utilizing the oxygen defect-rich metal catalysts, where missing oxygen atoms, or oxygen vacancies (VOs), contribute to the adsorption and geometry distortion of CO2, easing its reaction with H2. This review presents an overview of the potential of oxygen defect-rich catalysts for low-temperature CO2 hydrogenation, particularly focusing on those with supports such as CeO2, ZrO2, and TiO2. The fundamentals of VOs, including their types, impact, formation, and characterization techniques, are discussed, followed by an examination of their role in improving catalytic performance and steering reaction pathways towards methane and alcohols. Emphasis is placed on relevant optimization parameters, including catalyst features (metal loading and dispersion, type of metal, structure, etc.), presence and density of VOs and hydrogenation promoters, and reaction conditions (temperature, pressure, H2:CO2 feed ratio, flow rate). Recent advances are summarized, and lastly, current challenges and prospects are discussed.
Rahma Merza Hasan, Omar Mohamed Abdelsalam, A. Rawat et al.· Discover Nano· 0 citations
Background: Klebsiella pneumoniae is a major opportunistic pathogen responsible for a wide range of severe nosocomial and community-acquired infections. The rapid global dissemination of multidrug-resistant (MDR) and carbapenem-resistant K. pneumoniae (CRKP) strains severely restricts therapeutic alternatives and significantly raises patient mortality rates.
AIM: This study aimed to evaluate the antibiotic susceptibility pattern of K. pneumoniae from clinical isolates and evaluate the carbapenemase-producing strains using the rapid Carba NP test within a tertiary care hospital.
Materials & Methods: An observational cross-sectional study was conducted from May 2024 to July 2025 at the Department of Medical Microbiology, Santosh Medical College and Hospital (Ghaziabad) and Rama Medical College (Harpur). A total of 335 non-duplicated K. pneumoniae isolates collected from various clinical specimens (including urine, sputum, pus, and blood) across all age groups and genders were included. Bacterial identification was achieved through standard cultural characteristics and biochemical profiling. Antibiotic susceptibility testing (AST) was performed on Muller-Hinton agar using the Kirby-Bauer disc diffusion method, and phenotypic validation of carbapenemase production was executed using the Carba NP test in strict accordance with CLSI guidelines.
Results: Out of 335 isolates, the highest rate was retrieved from urine samples (40.3%), followed by sputum (26.6%) and pus (14.0%). The General Medicine ward presented the heaviest burden (54.43%), followed by Surgery (20.30%). The highest incidence occurred within the 51–60 age group (73 cases), demonstrating an overall male predominance in older populations, while a female predominance was isolated among young adults aged 21–30 years. In sensitivity pattern. Alarming rates of resistance were observed for ampicillin (>80% across sputum, pus, and blood) and early-to-late-generation cephalosporins. Carbapenems (meropenem and imipenem) sustained solid sensitivity in blood (84.4%) and urine (73.3% meropenem, 79.3% imipenem), but critical reduction in pus samples, where resistance rates were between 36.2% and 40.4%.
The Carba NP test successfully identified 45 phenotypic carbapenemase-producing isolates (yielding an overall positivity rate of 13.43%). Proportional carbapenemase positivity was most concentrated in endotracheal (ET) tube specimens (36.36%) and pus samples (31.91%).
Conclusions: The study shows an alarming level of multidrug resistance and a significant rise in carbapenemase producing K. pneumoniae isolates, particularly within device-associated (ET tube) and wound (pus) environments.
Zenab Naseem, A. Rawat, Muzaffari Yasmeen· Adolescência e Saúde· 0 citations
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