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1.
Artículo en Inglés | MEDLINE | ID: mdl-39292572

RESUMEN

This work investigates the problem of efficiently learning discriminative low-dimensional (LD) representations of multiclass image objects. We propose a generic end-to-end approach that jointly optimizes sparse dictionary and convolutions for learning LOW-dimensional discriminative image representations, named SparConvLow, taking advantage of convolutional neural networks (CNNs), dictionary learning, and orthogonal projections. The whole learning process can be summarized as follows. First, a CNN module is employed to extract high-dimensional (HD) preliminary convolutional features. Second, to avoid the high computational cost of direct sparse coding on HD CNN features, we learn sparse representation (SR) over a task-driven dictionary in the space with the feature being orthogonally projected. We then exploit the discriminative projection on SR. The whole learning process is consistently treated as an end-to-end joint optimization problem of trace quotient maximization. The cost function is well-defined on the product of the CNN parameters space, the Stiefel manifold, the Oblique manifold, and the Grassmann manifold. By using the explicit gradient delivery, the cost function is optimized via a geometrical stochastic gradient descent (SGD) algorithm along with the chain rule and the backpropagation. The experimental results show that the proposed method can achieve a highly competitive performance with the state-of-the-art (SOTA) image classification, object categorization, and face recognition methods, under both supervised and semi-supervised settings. The code is available at https://github.com/MVPR-Group/SparConvLow.

2.
Org Lett ; 2024 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-39248598

RESUMEN

Numerous effective bioisosteric replacements have been identified through substituting scaffolds and functional groups in lead molecules with alternative ones that preserve or enhance the desired biological activity of the original compound. Here, a copper-catalyzed nucleophilic cycloisomerization was developed to access potential bioisosteric replacements of azepinoindole. In this process, "tetra-alkene" characteristic of indolizine undergoes a 12π electrocyclization, offering a complementary method to obtain azepinoindolizine derivatives that are otherwise challenging to prepare through conventional means.

3.
Biomarkers ; : 1-8, 2024 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-39268816

RESUMEN

BACKGROUND: Previous studies have reported inconsistent results on the association between serum prealbumin level and survival outcomes in patients with gastric cancer. This meta-analysis aimed to determine the serum prealbumin level as a biomarker of survival outcomes in gastric cancer patients. METHODS: Two independent reviewers conducted a thorough search of PubMed, Embase, and Web of Science databases until April 17, 2024. Studies reporting the association between serum prealbumin level and survival outcomes and presented the multivariable-adjusted relative risks for gastric cancer patients were included. The pooled HR and 95% CI were used to assess the strength of the association. RESULTS: Twelve studies, with a total of 9,351 patients were included in the meta-analysis. The combined data showed that low serum prealbumin level was associated with shorter overall survival (HR 1.65; 95% CI 1.42-1.91) and disease-free survival (HR 1.39; 95% CI 1.14-1.70). Subgroup analysis showed that low serum prealbumin level significantly predicted poorer overall survival, regardless of patients' age, sample sizes, cutoff value for prealbumin level, and follow-up time. CONCLUSIONS: Low serum prealbumin level is an independent prognostic biomarker for shorter survival outcomes in patients with gastric cancer. Assessing serum prealbumin levels could potentially improve risk stratification for this disease.

4.
Adv Mater ; : e2408045, 2024 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-39177118

RESUMEN

Inefficient active site utilization of oxygen evolution reaction (OER) catalysts have limited the energy efficiency of proton exchange membrane (PEM) water electrolysis. Here, an atomic grid structure is demonstrated composed of high-density Ir sites (≈10 atoms per nm2) on reactive MnO2-x support which mediates oxygen coverage-enhanced OER process. Experimental characterizations verify the low-valent Mn species with decreased oxygen coordination in MnO2-x exert a pivotal impact in the enriched oxygen coverage on the surface during OER process, and the distributed Ir atomic grids, where highly electrophilic Ir─O(II-δ)- bonds proceed rapidly, render intense nucleophilic attack of oxygen radicals. Thereby, this metal-support cooperation achieves ultra-low overpotentials of 166 mV at 10 mA cm-2 and 283 mV at 500 mA cm-2, together with a striking mass activity which is 380 times higher than commercial IrO2 at 1.53 V. Moreover, its high OER performance also markedly surpasses the commercial Ir black catalyst in PEM electrolyzers with long-term stability.

5.
Foods ; 13(16)2024 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-39200522

RESUMEN

To further develop Liupao tea products and enhance their flavor, this study investigated the effects of different fermentation methods on the aroma quality of Liupao tea. The aroma quality of Liupao tea was comprehensively analyzed using HS-SPME in combination with GC-Q-TOF-MS, electronic nose, and sensory evaluations. Electronic nose detection showed that the aroma fingerprints of Liupao tea samples with different fermentation methods were different. Sulfides, alcohols, ketones, and methyls were the main aroma categories affecting the aroma of the four groups of Liupao tea samples. GC-Q-TOF-MS analysis revealed significant differences in the composition of aroma components among the four fermentation methods of Liupao tea (p < 0.05). Furthermore, the total amount of aroma compounds was found to be highest in the group subjected to hot fermentation combined with the inoculation of Monascus purpureus (DMl group). Based on the OPLS-DA model, candidate differential aroma components with VIP > 1 were identified, and characteristic aroma compounds were selected based on OAV > 10. The key characteristic aroma compounds shared by the four groups of samples were 1,2,3-Trimethoxybenzene with a stale aroma and nonanal with floral and fruity aromas. The best sensory evaluation results were obtained for the DMl group, and its key characteristic aroma compounds mainly included 1,2,3-Trimethoxybenzene, nonanal, and cedrol. The results of this study can guide the development of Liupao tea products and process optimization.

6.
Nat Commun ; 15(1): 6962, 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39138219

RESUMEN

Resolving the detailed structures of metal organic frameworks is of great significance for understanding their structure-property relation. Real-space imaging methods could exhibit superiority in revealing not only the local structure but also the bulk symmetry of these complex porous materials, compared to reciprocal-space diffraction methods, despite the technical challenges. Here we apply a low-dose imaging technique to clearly resolve the atomic structures of building units in a metal-organic framework, MIL-125. An unexpected node structure is discovered by directly imaging the rotation of Ti-O nodes, different from the unrotated structure predicted by previous X-ray diffraction. The imaged structure and symmetry can be confirmed by the structural simulations and energy calculations. Then, the distribution of node rotation from the edge to the center of a MIL-125 particle is revealed by the image analysis of Ti-O rotation. The related defects and surface terminations in MIL-125 are also investigated in the real-space images. These results not only unraveled the node symmetry in MIL-125 with atomic resolution but also inspired further studies on discovering more unpredicted structural changes in other porous materials by real-space imaging methods.

7.
Int J Legal Med ; 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39134883

RESUMEN

The PowerPlex® 35GY System (Promega, USA) is an advanced eight-dye multiplex STR kit, incorporating twenty-three autosomal STR loci, eleven Y chromosome STR loci, one sex determining marker Amelogenin, and two quality indicators. This multiplex system includes 20 CODIS loci and up to 15 mini-STR loci with sizing values less than 250 bases. In this study, validation for PowerPlex® 35GY System was conducted following the guidelines of SWGDAM, encompassing sensitivity, precision, accuracy, concordance, species specificity, stutter, mixture, stability, and degraded DNA. The results from experiments demonstrated that the PowerPlex® 35GY System could effectively amplify DNA samples, with complete allele detection achieved at 125 pg. Moreover, over 90% of alleles from minor contributors were detected at a mixed ratio of 1:4. Additionally, the system was found to yield full profiles even in the presence of hematin, humic acid, and indigo. The PowerPlex® 35GY System demonstrated superior performance in the sensitivity and degraded DNA studies compared to a six-dye STR kit. Hence, it is evident that the PowerPlex® 35GY System is well-suited for forensic practice, whether in casework or for database samples. These findings provide strong support for the efficacy and reliability of the PowerPlex® 35GY System in forensic applications.

8.
Int J Legal Med ; 2024 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-39191920

RESUMEN

BACKGROUND: Small amounts of DNA from a perpetrator collected during crime-scene investigations can be masked by large amounts of DNA from the victim. These samples can provide important information for the perpetrator's conviction. Short tandem repeat (STR) detection system is not sensitive enough to detect trace amounts of minor components in unbalanced mixed DNA. We developed a system using droplet digital polymerase chain reaction (ddPCR) capable of discovering trace components and accurately determining the ratio of mixed DNA in extremely unbalanced mixtures. METHODS: The non-recombining regions of the X chromosome and Y chromosome were quantified in the DNA of male and female mixtures using duplex ddPCR. Absolute quantification of low-abundance portions of trace samples and unbalanced mixtures was done using different mixing ratios. RESULTS: The ddPCR system could be used to detect low-abundance samples with < 5 copies of DNA components in an extremely unbalanced mixture at a mixing ratio of 10000:1. The high sensitivity and specificity of the system could identify the mixing ratio of mixed DNA accurately. CONCLUSIONS: A ddPCR system was developed for evaluation of mixed samples of male DNA and female DNA. Our system could detect DNA quantities as low as 5 copies in extremely unbalanced mixed samples with good specificity and applicability. This method could assist forensic investigators in avoiding the omission of important physical evidence, and evaluating the ratio of mixed male/female trace samples.

9.
ACS Appl Mater Interfaces ; 16(33): 43556-43564, 2024 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-39132739

RESUMEN

Atomic-scale insights into the interactions between metals and supports play a crucial role in optimizing catalyst design, understanding catalytic mechanisms, and enhancing chemical conversion processes. The effects of oxide support on the dynamic behavior of supported metal species during pretreatments or reactions have been attracting a lot of attention; however, very less systematic integrations are carried out experimentally using real catalysts. In this study, we here utilized facet-controlled CeO2 as examples to explore their influence on the supported Pt species (1.0 wt %) during the reducing and oxidizing pretreatments that are typically applied in heterogeneous catalysts. By employing a combination of microscopy, spectroscopy, and first-principles calculations, it is demonstrated that the exposed crystal facets of CeO2 govern the evolution behavior of supported Pt species under different environmental conditions. This leads to distinct local coordinations and charge states of the Pt species, which directly influence the catalytic reactivity and can be leveraged to control the catalytic performance for CO oxidation reactions.

10.
Physiol Mol Biol Plants ; 30(6): 877-891, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38974354

RESUMEN

Natural leaf senescence is critical for plant fitness. Drought-induced premature leaf senescence affects grape yield and quality. However, reports on the regulatory mechanisms underlying premature leaf senescence under drought stress are limited. In this study, two-year-old potted 'Muscat Hamburg' grape plants were subjected to continuous natural drought treatment until mature leaves exhibited senescence symptoms. Physiological and biochemical indices related to drought stress and senescence were monitored. Transcriptome and transgenic Arabidopsis were used to perform expression analyses and functional identification of drought-induced senescence-associated genes. Twelve days of continuous drought stress was sufficient to cause various physiological disruptions and visible senescence symptoms in mature 'Muscat Hamburg' leaves. These disruptions included malondialdehyde and H2O2 accumulation, and decreased catalase activity and chlorophyll (Chl) levels. Transcriptome analysis revealed that most genes involved in photosynthesis and Chl synthesis were downregulated after 12 d of drought treatment. Three key Chl catabolic genes (SGR, NYC1, and PAO) were significantly upregulated. Overexpression of VvSGR in wild Arabidopsis further confirmed that SGR directly promoted early yellowing of cotyledons and leaves. In addition, drought treatment decreased expression of gibberellic acid signaling repressors (GAI and GAI1) and cytokinin signal components (AHK4, AHK2, RR22, RR9-1, RR9-2, RR6, and RR4) but significantly increased the expression of abscisic acid, jasmonic acid, and salicylic acid signaling components and responsive transcription factors (bZIP40/ABF2, WRKY54/75/70, ANAC019, and MYC2). Moreover, some NAC members (NAC0002, NAC019, and NAC048) may also be drought-induced senescence-associated genes. These results provide extensive information on candidate genes involved in drought-induced senescence in grape leaves. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01465-2.

11.
World J Psychiatry ; 14(6): 812-821, 2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38984333

RESUMEN

BACKGROUND: Psychological problems are becoming increasingly prominent among older patients with leukemia, with patients potentially facing stigmatization after diagnosis. However, there is limited research on the stigma experienced by these patients and the factors that may contribute to it. AIM: To investigate the stigma faced by older patients after being diagnosed with leukemia and to analyze the potential influencing factors. METHODS: A retrospective analysis was conducted using clinical data obtained from questionnaire surveys, interviews, and the medical records of older patients with leukemia admitted to the Hengyang Medical School from June 2020 to June 2023. The data obtained included participants' basic demographic information, medical history, leukemia type, family history of leukemia, average monthly family income, pension, and tendency to conceal illness. The Chinese versions of the Social Impact Scale (SIS), Perceived Social Support Scale (PSSS), Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS) were used to assess indicators related to stigma, social support, and mental health status. We used Pearson's correlation coefficient to analyze the strength and direction of the relationship between the scores of each scale, and regression analysis to explore the factors related to the stigma of older patients with leukemia after diagnosis. RESULTS: Data from 120 patients with leukemia aged 65-80 years were analyzed. The total score on the SIS and PSSS was 43.60 ± 4.07 and 37.06 ± 2.87, respectively. The SAS score was 58.35 ± 8.32 and the SDS score was 60.58 ± 5.97. The stigma experienced by older leukemia patients was negatively correlated with social support (r = -0.691, P < 0.05) and positively correlated with anxiety and depression (r = 0.506, 0.382, P < 0.05). Age, education level, smoking status, average monthly family income, pension, and tendency to conceal illness were significantly associated with the participants' level of stigma (P < 0.05). Age, smoking status, social support, anxiety, and depression were predictive factors of stigmatization among older leukemia patients after diagnosis (all P < 0.05), with a coefficient of determination (R2) of 0.644 and an adjusted R2 of 0.607. CONCLUSION: Older patients commonly experience stigmatization after being diagnosed with leukemia. Factors such as age, smoking status, social support, and psychological well-being may influence older patients' reported experience of stigma.

12.
Front Pharmacol ; 15: 1402763, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38994201

RESUMEN

Naoxintong Capsule (NXT), a renowned traditional Chinese medicine (TCM) formulation, has been broadly applied in China for more than 30 years. Over decades, accumulating evidences have proven satisfactory efficacy and safety of NXT in treating cardiovascular and cerebrovascular diseases (CCVD). Studies have been conducted unceasingly, while this growing latest knowledge of NXT has not yet been interpreted properly and summarized comprehensively. Hence, we systematically review the advancements in NXT research, from its chemical constituents, quality control, pharmacokinetics, to its profound pharmacological activities as well as its clinical applications in CCVD. Moreover, we further propose specific challenges for its future perspectives: 1) to precisely clarify bioactivities of single compound in complicated mixtures; 2) to evaluate the pharmacokinetic behaviors of NXT feature components in clinical studies, especially drug-drug interactions in CCVD patients; 3) to explore and validate its multi-target mechanisms by integrating multi-omics technologies; 4) to re-evaluate the safety and efficacy of NXT by carrying out large-scale, multicenter randomized controlled trials. In brief, this review aims to straighten out a paradigm for TCM modernization, which help to contribute NXT as a piece of Chinese Wisdom into the advanced intervention strategy for CCVD therapy.

13.
J Prosthet Dent ; 2024 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-39079818

RESUMEN

This article describes a completely digital workflow for ceramic veneer preparation with computer-aided design and computer-aided manufacturing technology. A simplified 3-dimensionally printed tooth reduction guide for accurate intraoral trial restorations is manufactured to indicate the range of the unprepared tooth surfaces erupted beyond the digital esthetic waxing. By using the Medit Design software program, chairside tooth preparation is monitored by accurate measurement of the amount of tooth reduction relative to the required restorative contours. Compared with conventional techniques, this technique improves the control and efficiency of tooth preparation, aiding in enamel preservation and achieving a predictable prosthetic effect.

14.
Nutr Cancer ; 76(9): 815-823, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38943494

RESUMEN

The cachexia index is a novel indicator of cachexia, but its prognostic implications for survival outcomes have not been systematically assessed in patients with gastrointestinal cancer. This systematic review and meta-analysis aimed to examine the association between the cachexia index and survival outcomes in gastrointestinal cancer patients. Two independent reviewers searched PubMed, Embase, and Web of Science to identify studies that evaluated the prognostic significance of the cachexia index in patients with gastrointestinal cancer. The prognostic value of the cachexia index was determined by combining the adjusted hazard ratios (HR) and 95% confidence intervals (CI). Thirteen studies were identified, including a total of 4207 patients. Meta-analysis indicated that a lower cachexia index was associated with shorter overall survival (HR 2.18; 95% CI 1.78-2.66) and disease-free survival (HR 1.72; 95% CI 1.50-1.97) in gastrointestinal cancer patients. Further stratified analysis confirmed the significant association between a lower cachexia index and shorter overall survival in different study designs, regions, patients' age, sample sizes, gastrointestinal cancer subtypes, tumor stages, and follow-up duration subgroups. The cachexia index could be utilized as a predictor of overall survival and disease-free survival in patients with gastrointestinal cancer. However, future prospective studies are required to confirm these findings.


Asunto(s)
Caquexia , Neoplasias Gastrointestinales , Caquexia/mortalidad , Caquexia/etiología , Humanos , Neoplasias Gastrointestinales/mortalidad , Neoplasias Gastrointestinales/complicaciones , Pronóstico , Supervivencia sin Enfermedad
15.
J Agric Food Chem ; 72(26): 15027-15039, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38886897

RESUMEN

Abscisic acid (ABA) is a major regulator of nonclimacteric fruit ripening, with its processes involving epigenetic mechanisms. It remains unclear whether DNA methylation is associated with ABA-regulated ripening. In this study, we investigated the patterns of DNA methylation and gene expression following ABA treatment in grape berries by using whole-genome bisulfite sequencing and RNA-sequencing. ABA application changed global DNA methylation in grapes. The hyper-/hypo-differently methylated regions were enriched in defense-related metabolism, degreening processes, or ripening-related metabolic pathways. Many differentially expressed genes showed an alteration in DNA methylation after ABA treatment. Specifically, ten downregulated genes with hypermethylation in promoters were involved in the ripening process, ABA homeostasis/signaling, and stress response. Nine upregulated genes exhibiting hypo-methylation in promoters were related to the ripening process and stress response. These findings demonstrated ABA-induced DNA alteration of ripening related and stress-responsive genes during grape ripening, which provides new insights of the epigenetic regulation of ABA on fruit ripening.


Asunto(s)
Ácido Abscísico , Metilación de ADN , Epigénesis Genética , Frutas , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas , Vitis , Vitis/genética , Vitis/crecimiento & desarrollo , Vitis/metabolismo , Vitis/efectos de los fármacos , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacología , Metilación de ADN/efectos de los fármacos , Frutas/genética , Frutas/crecimiento & desarrollo , Frutas/metabolismo , Frutas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Epigénesis Genética/efectos de los fármacos , Estrés Fisiológico/genética , Reguladores del Crecimiento de las Plantas/farmacología , Reguladores del Crecimiento de las Plantas/metabolismo , Regiones Promotoras Genéticas
17.
Front Endocrinol (Lausanne) ; 15: 1409267, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38904038

RESUMEN

Introduction: To explore whether blood flow-restrictive resistance exercise (BFRE) can be used as an alternative strategy to moderate-intensity resistance training (RT) to improve metabolic disorder and body composition in older adults with type 2 diabetes (T2DM). Methods: This is a single-blind, randomized, controlled trial. Ninety-eight older adults with T2DM were randomly divided into three groups: BFRE group (n = 34), RT group (n = 31) and control group (n = 33). Two exercise groups received supervised collective training for a period of six months, each lasting 50 min, three times a week. The primary outcomes included fasting plasma glucose (FPG), Glycosylated hemoglobin (HbA1c), blood lipids, blood pressure, and body composition. The secondary outcome was muscle performance. Results: After six months of intervention, the FPG, HbA1c, blood lipids, diastolic blood pressure, body composition, and muscle performance of the two exercise groups were significantly improved relative to the control group and baseline measurements (P < 0.05). There was no significant increase in lean mass between the two exercise groups compared to the control group and baseline (p > 0.05). There was no significant decrease in systolic blood pressure between the two exercise groups compared to the control group (p > 0.05), but it was significantly lower than their baseline (P < 0.05). There was no significant difference in all indicators between the two exercise groups at the baseline, third and sixth months of intervention (p > 0.05). Discussion: BFRE can safely and effectively improve the metabolic disorder and body composition of older adults with T2DM. For elderly exercise beginners, BFRE can be used as an alternative strategy to moderate-intensity resistance training. Clinical trial registration: https://www.chictr.org.cn/showproj.html?proj=178886, identifier ChiCTR2300074357.


Asunto(s)
Composición Corporal , Diabetes Mellitus Tipo 2 , Entrenamiento de Fuerza , Humanos , Diabetes Mellitus Tipo 2/terapia , Diabetes Mellitus Tipo 2/fisiopatología , Diabetes Mellitus Tipo 2/sangre , Entrenamiento de Fuerza/métodos , Masculino , Femenino , Anciano , Método Simple Ciego , Persona de Mediana Edad , Hemoglobina Glucada/análisis , Hemoglobina Glucada/metabolismo , Glucemia/metabolismo , Presión Sanguínea/fisiología , Flujo Sanguíneo Regional/fisiología , Lípidos/sangre
18.
J Med Chem ; 67(12): 9991-10004, 2024 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-38888038

RESUMEN

Different from most antiretroviral drugs that act as passive defenders to inhibit HIV-1 replication inside the host cell, virus inactivators can attack and inactivate HIV-1 virions without relying on their replication cycle. Herein, we describe the discovery of a hydrocarbon double-stapled helix peptide, termed D26. D26 is based on the HIV-1 gp41 protein lentiviral lytic peptide-3 motif (LLP3) sequence, which can efficiently inhibit HIV-1 infection and inactivate cell-free HIV-1 virions. It was noted that D26 was highly resistant to proteolytic degradation and exhibited a remarkably extended in vivo elimination half-life. Additionally, relative to its linear, nonstapled version, D26 exhibited much higher exposure in sanctuary sites for HIV-1. Amazingly, this lead compound also demonstrated detectable oral absorption. Thus, it can be concluded that D26 is a promising candidate for further development as a long-acting, orally applicable HIV-1 inactivator for the treatment of HIV-1 infection.


Asunto(s)
Fármacos Anti-VIH , Disponibilidad Biológica , Proteína gp41 de Envoltorio del VIH , VIH-1 , Péptidos , VIH-1/efectos de los fármacos , Fármacos Anti-VIH/farmacología , Fármacos Anti-VIH/química , Fármacos Anti-VIH/farmacocinética , Humanos , Animales , Administración Oral , Proteína gp41 de Envoltorio del VIH/metabolismo , Proteína gp41 de Envoltorio del VIH/química , Péptidos/química , Péptidos/farmacología , Péptidos/farmacocinética , Descubrimiento de Drogas , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/virología , Semivida
19.
Environ Sci Technol ; 58(27): 12201-12211, 2024 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-38934498

RESUMEN

The elevation of the low-temperature oxidation activity for Pt/CeO2 catalysts is challenging to meet the increasingly stringent requirements for effectively eliminating carbon monoxide (CO) from automobile exhaust. Although reducing activation is a facile strategy for boosting reactivity, past research has mainly concentrated on applying H2 as the reductant, ignoring the reduction capabilities of CO itself, a prevalent component of automobile exhaust. Herein, atomically dispersed Pt/CeO2 was fabricated and activated by CO, which could lower the 90% conversion temperature (T90) by 256 °C and achieve a 20-fold higher CO consumption rate at 200 °C. The activated Pt/CeO2 catalysts showed exceptional catalytic oxidation activity and robust hydrothermal stability under the simulated working conditions for gasoline or diesel exhausts. Characterization results illustrated that the CO activation triggered the formation of a large portion of Pt0 terrace sites, acting as inherent active sites for CO oxidation. Besides, CO activation weakened the Pt-O-Ce bond strength to generate a surface oxygen vacancy (Vo). It served as the oxygen reservoir to store the dissociated oxygen and convert it into active dioxygen intermediates. Conversely, H2 activation failed to stimulate Vo, but triggered a deactivating transformation of the Pt nanocluster into inactive PtxOy in the presence of oxygen. The present work offers coherent insight into the upsurging effect of CO activation on Pt/CeO2, aiming to set up a valuable avenue in elevating the efficiency of eliminating CO, C3H6, and NH3 from automobile exhaust.


Asunto(s)
Monóxido de Carbono , Oxidación-Reducción , Catálisis , Monóxido de Carbono/química , Emisiones de Vehículos , Platino (Metal)/química , Cerio/química
20.
Malays Fam Physician ; 19: 30, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38855397

RESUMEN

Introduction: The prevalence of visual impairment and ocular diseases changes over time. This measure can help general practitioners in anticipating common eye disorders that may require ophthalmological referrals to government hospitals. This study aimed to evaluate the prevalence of visual impairment and ocular diseases in an outpatient ophthalmology clinic in a public hospital and the types of investigations frequently conducted to diagnose these diseases. Methods: A cross-sectional prospective study was conducted over three weeks in the eye clinic of the University of Malaya Medical Centre. The electronic medical records of all patients who attended the outpatient clinic were assessed to collect data on sex, age, type of visit, visual acuity, ocular presentation, investigations conducted and diagnosis of eye diseases. Visual impairment and blindness were categorised as per the World Health Organization criteria. Results: Among 1002 patients, 327 had visual impairments (32.63%), and nine had blindness (0.9%). Cataracts were the most common ocular disease diagnosed (n=294, 29.74%), followed by glaucoma (n=123, 12.28%) and diabetic retinopathy (n=84, 8.38%). Optical coherence tomography was the most common investigation performed (n=272, 64.9%), followed by Humphrey visual field testing (n=53,12.6%). Conclusion: Untreated refractive error is the leading cause of visual impairment in children, while cataract, glaucoma and diabetic retinopathy are the main contributors to visual impairment and blindness in elderly individuals. Our study highlights the urgent need for general practitioners to recognise avoidable visual impairment in all age groups to help prevent blindness.

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