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1.
Int Heart J ; 65(3): 528-536, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38825497

RESUMO

Cardiomyocyte hypertrophy plays a crucial role in heart failure development, potentially leading to sudden cardiac arrest and death. Previous studies suggest that micro-ribonucleic acids (miRNAs) show promise for the early diagnosis and treatment of cardiomyocyte hypertrophy.To investigate the miR-378 expression in the cardiomyocyte hypertrophy model, reverse transcription-polymerase chain reaction (RT-qPCR), Western blot, and immunofluorescence tests were conducted in angiotensin II (Ang II)-induced H9c2 cells and Ang II-induced mouse model of cardiomyocyte hypertrophy. The functional interaction between miR-378 and AKT2 was studied by dual-luciferase reporter, RNA pull-down, Western blot, and RT-qPCR assays.The results of RT-qPCR analysis showed the downregulated expression of miR-378 in both the cell and animal models of cardiomyocyte hypertrophy. It was observed that the introduction of the miR-378 mimic inhibited the hypertrophy of cardiomyocytes induced by Ang II. Furthermore, the co-transfection of AKT2 expression vector partially mitigated the negative impact of miR-378 overexpression on Ang II-induced cardiomyocytes. Molecular investigations provided evidence that miR-378 negatively regulated AKT2 expression by interacting with the 3' untranslated region (UTR) of AKT2 mRNA.Decreased miR-378 expression and AKT2 activation are linked to Ang II-induced cardiomyocyte hypertrophy. Targeting miR-378/AKT2 axis offers therapeutic opportunity to alleviate cardiomyocyte hypertrophy.


Assuntos
Angiotensina II , MicroRNAs , Miócitos Cardíacos , Proteínas Proto-Oncogênicas c-akt , MicroRNAs/genética , MicroRNAs/metabolismo , Animais , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Camundongos , Cardiomegalia/metabolismo , Cardiomegalia/genética , Modelos Animais de Doenças , Ratos , Masculino , Camundongos Endogâmicos C57BL , Células Cultivadas
2.
Opt Express ; 32(11): 18958-18971, 2024 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-38859041

RESUMO

Focused vector beams (VBs) are important topic in the areas of light field manipulation. Geometric metasurfaces provide a convenient platform to facilitate the generation of focused VBs. In this study, we propose a dielectric geometric metasurface to generate multichannel focused higher-order Poincaré sphere (HOP) beams. With identical meta-atoms of half-wave plate, the metasurface comprises two sub-metasurfaces, and each of them includes two sets of rings related to Fresnel zones. For meta-atoms on each set of rings, the hyperbolic geometric phase profile is configured so that the mirror-symmetrical position-flip of the off-axis focal point is enabled under the chirality switch of the illuminating circular polarization. With the design of helical geometric phase profiles for the two sets of rings, a sub-metasurface generate two HOP beams at the symmetrical two focal points. The performance of the two sub-metasurfaces enables the metasurface with four sets of rings to generate the array of four HOP beams. The proposed method was validated by theoretical analyses, numerical simulation and experimental conduction. This research would be significant in miniaturizing and integrating optical systems involving applications of VB generations and applications.

3.
World J Mens Health ; 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38772541

RESUMO

PURPOSE: Erectile dysfunction (ED) is a common male sexual dysfunction. Gut microbiota plays an important role in various diseases. To investigate the effects and mechanisms of intestinal flora dysregulation induced by high-fat diet (HFD) on erectile function. MATERIALS AND METHODS: Male Sprague-Dawley rats aged 8 weeks were randomly divided into the normal diet (ND) and HFD groups. After 24 weeks, a measurement of erectile function was performed. We performed 16S rRNA sequencing of stool samples. Then, we established fecal microbiota transplantation (FMT) rat models by transplanting fecal microbiota from rats of ND group and HFD group to two new groups of rats respectively. After 24 weeks, erectile function of the rats was evaluated and 16S rRNA sequencing was performed, and serum samples were collected for the untargeted metabolomics detection. RESULTS: The erectile function of rats and the species diversity of intestinal microbiota in the HFD group was significantly lower, and the characteristics of the intestinal microbiota community structure were also significantly different between the two groups. The erectile function of rats in the HFD-FMT group was significantly lower than that of rats in the ND-FMT group. The characteristics of the intestinal microbiota community structure were significantly different. In the HFD-FMT group, 27 metabolites were significantly different and they were mainly involved in the several inflammation-related pathways. CONCLUSIONS: Intestinal microbiota disorders induced by HFD can damage the intestinal barrier of rats, change the serum metabolic profile, induce low-grade inflammation and apoptosis in the corpus cavernosum of the penis, and lead to ED.

4.
Food Sci Nutr ; 12(3): 2122-2130, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38455207

RESUMO

The association of dietary inflammatory index (DII) with constipation has not been well studied in general population. Therefore, the aim of this cross-sectional study was to investigate whether DII is associated with constipation in a large representative sample of the US population. Data were obtained from the 2005-2010 National Health and Nutrition Examination Survey (NHANES). A total of 12,308 participants aged ≥20 years were included in the analysis. DII was calculated based on a single 24-h dietary recall, and constipation was defined as having fewer than three bowel movements per week by the questionnaire on bowel health. Logistic regression analysis demonstrated a significant positive association between DII score and constipation, with each unit increase in DII score associated with a 20% increase in constipation risk (95% CI: 1.13-1.28). Subgroup analysis revealed high odds ratios (ORs) among individuals classified as "Other Race" (OR: 1.42, 95% CI: 1.12-1.80) and "Non-Hispanic White" (OR: 1.31, 95% CI: 1.12-1.54). In addition, RCS analysis indicated a nonlinear relationship between DII and constipation among individuals with a BMI less than 25 (OR: 1.17, 95% CI: 1.07-1.28), while the overall trend remained positive correlation (OR: 1.20, 95% CI: 1.10-1.31). Briefly, our study suggests that there may be a link between DII and constipation, which has implications for the development of dietary interventions aimed at preventing and managing constipation. However, this association was complex and variable depending on individual factors such as BMI and racial background and needed to establish longitudinal studies to confirm the underlying mechanisms between DII and constipation.

5.
Zhongguo Zhong Yao Za Zhi ; 49(1): 268-278, 2024 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-38403359

RESUMO

This study aims to assess the safety and efficacy of Shumian Capsules in the treatment of insomnia. Randomized controlled trial(RCT) about Shumian Capsules for insomnia were retrieved from databases. RevMan 5.4 was used for statistical analysis. A total of 23 articles were included, involving 2 621 patients. Meta-analysis showed that Shumian Capsules had advantages in the treatment of insomnia(RR=1.07, 95%CI[1.03, 1.10], P=0.000 2) and insomnia with depression(RR=1.13, 95%CI[1.02, 1.25], P=0.02) in terms of total response rate. Shumian Capsules had advantages in the treatment of insomnia(MD=-0.75, 95%CI[-1.33,-0.17], P=0.01) and insomnia with depression(MD=-2.51, 95%CI[-2.96,-2.06], P<0.000 01) in terms of PSQI score. The incidence of adverse events in the Shumian Capsules(RR=0.33, 95%CI[0.24, 0.46], P<0.000 01) and Shumian Capsules + conventional western medicine(RR=0.71, 95%CI[0.54, 0.95], P=0.02) was lower than that in the conventional wes-tern medicine alone. In addition, Shumian Capsules had an advantage in treating insomnia complicated with depression in terms of HAMD score(P<0.000 1) and reducing the serum levels of 5-HT, TSH, T3, and T4 in insomnia patients(P<0.05). The quality of evidence was mostly medium or low. The studies demonstrate that Shumian Capsules is effective and safe for treating insomnia, which may be related to the mechanism of lowering the levels of 5-HT, TSH, T3, and T4 in the serum. In view of the quality of evidence, the application of Shumian Capsules should be considered after comprehensive evaluation in clinical practice.


Assuntos
Medicamentos de Ervas Chinesas , Distúrbios do Início e da Manutenção do Sono , Humanos , Distúrbios do Início e da Manutenção do Sono/tratamento farmacológico , Distúrbios do Início e da Manutenção do Sono/induzido quimicamente , Medicamentos de Ervas Chinesas/efeitos adversos , Serotonina , Cápsulas , Tireotropina
6.
Nanomaterials (Basel) ; 14(4)2024 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-38392746

RESUMO

Metasurfaces of quarter-wave plate (QWP) meta-atoms have exhibited high flexibility and versatile functionalities in the manipulation of light fields. However, the generation of multi-channel vortex beams with the QWP meta-atom metasurfaces presents a significant challenge. In this study, we propose dielectric metasurfaces composed of QWP meta-atoms to manipulate multi-channel vortex beams. QWP meta-atoms, systematically arranged in concentric circular rings, are designed to introduce the modulations via the propagation phase and geometric phase, leading to the generation of co- and cross-polarized vortex beams in distinct channels. Theoretical investigations and simulations are employed to analyze the modulation process, confirming the capability of QWP meta-atom metasurfaces for generating the multi-channel vortex beams. This study presents prospective advancements for the compact, integrated, and multifunctional nanophotonic platforms, which have potential applications in classical physics and quantum domains.

7.
Integr Med Res ; 13(1): 101019, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38298865

RESUMO

Background: With the development of traditional Chinese medicine (TCM) syndrome knowledge accumulation and artificial intelligence (AI), this study proposes a holistic TCM syndrome differentiation model for the classification prediction of multiple TCM syndromes based on deep learning and accelerates the construction of modern foundational TCM equipment. Methods: We searched publicly available TCM guidelines and textbooks for expert knowledge and validated these sources using ten-fold cross-validation. Based on the BERT and CNN models, with the classification constraints from TCM holistic syndrome differentiation, the TCM-BERT-CNN model was constructed, which completes the end-to-end TCM holistic syndrome text classification task through symptom input and syndrome output. We assessed the performance of the model using precision, recall, and F1 scores as evaluation metrics. Results: The TCM-BERT-CNN model had a higher precision (0.926), recall (0.9238), and F1 score (0.9247) than the BERT, TextCNN, LSTM RNN, and LSTM ATTENTION models and achieved superior results in model performance and predictive classification of most TCM syndromes. Symptom feature visualization demonstrated that the TCM-BERT-CNN model can effectively identify the correlation and characteristics of symptoms in different syndromes with a strong correlation, which conforms to the diagnostic characteristics of TCM syndromes. Conclusions: The TCM-BERT-CNN model proposed in this study is in accordance with the TCM diagnostic characteristics of holistic syndrome differentiation and can effectively complete diagnostic prediction tasks for various TCM syndromes. The results of this study provide new insights into the development of deep learning models for holistic syndrome differentiation in TCM.

8.
Asian J Surg ; 47(5): 2178-2187, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38395709

RESUMO

BACKGROUND: Retinoblastoma (RB) is a rare primary malignant tumor primarily affecting children. Our study aims to compare the overall survival (OS) between pediatric and adult RB patients and establish a predictive model for adult RB patients' OS to assist clinical decision-making. METHODS: This study retrospectively analyzed data from 1938 RB patients in the Surveillance, Epidemiology, and End Results (SEER) database, covering the period from 2000 to 2015. Propensity score matching (PSM) ensured balanced characteristics between pediatric and adult groups. A Cox proportional hazards regression model was used to assess prognostic factors, and selected variables were utilized to construct a predictive survival model. The Nomogram model's performance was evaluated through the C-index, time-dependent ROC curves, calibration curves, and decision curve analysis (DCA). RESULTS: Following PSM, adult RB patients had lower OS compared to pediatric RB patients. Independent prognostic factors for adult RB OS included age, gender, disease stage, radiation therapy, income, and diagnosis confirmation. In the training cohort, the Nomogram achieved a C-index for OS of 0.686 and accurately predicted 2-year, 3-year, and 5-year OS with AUC values of 0.672, 0.680, and 0.660, respectively. The C-index, time-dependent ROC curves, calibration curves, and DCA in both training and validation cohorts confirmed the Nomogram's excellent performance. CONCLUSION: In this study, adult RB patients have worse OS than pediatric RB patients. Consequently, we constructed a Nomogram to predict the risk for adult RB patients. The Nomogram demonstrated good accuracy and reliability, making it suitable for widespread application in clinical practice to assist healthcare professionals in assessing patients' prognoses.


Assuntos
Nomogramas , Neoplasias da Retina , Retinoblastoma , Programa de SEER , Humanos , Retinoblastoma/mortalidade , Retinoblastoma/terapia , Masculino , Feminino , Adulto , Estudos Retrospectivos , Neoplasias da Retina/mortalidade , Neoplasias da Retina/terapia , Neoplasias da Retina/patologia , Criança , Pessoa de Meia-Idade , Fatores Etários , Prognóstico , Adolescente , Adulto Jovem , Taxa de Sobrevida , Pré-Escolar , Lactente , Modelos de Riscos Proporcionais , Pontuação de Propensão , Estadiamento de Neoplasias
9.
Zootaxa ; 5397(1): 135-140, 2024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38221214

RESUMO

One new species of leaf katydids, Elimaea (Poaefoliana) kiukiangensis sp. nov. from the Himalaya-Hengduan Mountains region, is described, based on recently collected material. Illustrations of mounted specimens including male genitalia, and habitat images are provided. A distribution map is also provided. The types are deposited in Insect Collection of Institute of Zoology, Chinese Academy of Sciences, Beijing, China (IZCAS).


Assuntos
Ortópteros , Masculino , Animais , China , Ecossistema , Academias e Institutos , Distribuição Animal
10.
Int J Biol Macromol ; 260(Pt 2): 129527, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38246435

RESUMO

Oxidative stress-induced enteric neuropathy is an important factor in slow transit constipation (STC). Cistanche deserticola crude polysaccharides (CDCP) are natural antioxidants with various biological activities. We prepared CDCP through water-extract and alcohol-precipitation methods. The structural characteristics of CDCP were analyzed by infrared spectroscopy and methylation analysis. The results showed that CDCP was primarily composed of (1 â†’ 4)-linked glucans with minor amounts of pectic polysaccharides. Different doses of CDCP (100, 200, and 400 mg/kg) were administered to loperamide-induced STC mice to explore the therapeutic effects of CDCP. Compared with the untreated group, CDCP treatment significantly improved constipation symptoms, relevant gut-regulating peptides levels, colonic pathological damage, and colonic myenteric nerons injury. CDCP enhanced the antioxidant capacity by decreasing Malondialdehyde (MDA) content, increasing Superoxide Dismutase (SOD) activity and Reduced Glutathione (GSH) content. CDCP significantly reduced oxidative stress-induced injury by preserving mitochondrial function in the colonic myenteric plexus. Furthermore, the neuroprotective effects of CDCP might be associated with the Nrf2/Keap1 pathway. Thus, our findings first revealed the potential of CDCP to protect the colonic myenteric plexus against oxidative stress-induced damage in STC, establishing CDCP as promising candidates for natural medicine in the clinical management of STC.


Assuntos
Cistanche , Fármacos Neuroprotetores , Camundongos , Animais , Cistanche/química , Fármacos Neuroprotetores/farmacologia , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Constipação Intestinal/induzido quimicamente , Constipação Intestinal/tratamento farmacológico , Constipação Intestinal/metabolismo , Estresse Oxidativo , Antioxidantes/farmacologia , Antioxidantes/metabolismo , Polissacarídeos/farmacologia , Polissacarídeos/química
11.
Environ Sci Pollut Res Int ; 31(5): 8012-8025, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38175509

RESUMO

Annular pool fires, frequently happened in chemical industries, have a significant influence on environmental pollution. Air pollution, greenhouse gas emissions, water pollution, and soil contamination are general ways of environmental hazards caused by the annular pool fires. This study built upon our previous study (Environ. Sci. Pollut. Res., 2023, 30(21): 59781-59792.), and extended to investigate the combustion and fire plume flow behaviors of annular pool fires, both with and without air entrainment through the hollow center of the annular pool. Results show that when there is no air entrainment through the hollow center, the low combustion intensity area at the plume's central axis gradually extends while the high combustion intensity area concentrates at higher places and the flame height increased by nearly 40% from a solid pool (Din/Dout = 0) to the annular pool (Din/Dout = 0.80). Additionally, the area with high combustion intensity is more concentrated at a higher position. The combustion of annular pool fires was found to be dominated by non-premixed diffusion combustion. The center of the annular pool fires is dominated by air prior to flame merging and by fuel vapor after the merging occurs. For annular pool fires with air entrainment through the center of the pool, the combustion intensity increases as Din/Dout at the plume base increases. And, the flame height decreased by nearly 25% as Din/Dout increases. Flame burning occurs both on the outside and inside of the plume, exhibiting a "double layer" combustion characteristic. It reveals that the combustion of the fire plume transitions to premixed diffusion combustion. The center of the annular pool fire is predominantly composed of air. Understanding and controlling annular pool fires can lead to new methods for remediating fuel spills, reducing pollution from combustion, and advancing research in fluid mechanics.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Incêndios , Gases de Efeito Estufa , Gases , Poluição da Água
12.
Small ; 20(12): e2308216, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37946696

RESUMO

The ternary strategy is one of the effective methods to regulate the morphology of the active layer in organic solar cells (OSCs). In this work, the ternary OSCs with bulk heterojunction (BHJ) or layer-by-layer (LbL) active layers are prepared by using the polymer donor PM6 and the non-fullerene acceptor L8-BO as the main system and the fullerene acceptor PC71BM as the third component. The power conversion efficiencies (PCEs) of BHJ OSCs and LbL OSCs are increased from 17.10% to 18.02% and from 17.20% to 18.20% by introducing PC71BM into the binary active layer, respectively. The in situ UV-vis absorption spectra indicate that the molecular aggregation and crystallization process can be prolonged by introducing PC71BM into the PM6:L8-BO or PM6/L8-BO active layer. The molecular orientation and molecular crystallinity in the active layer are optimized by introducing the PC71BM into the binary BHJ or LbL active layers, which can be confirmed by the experimental results of grazing incidence wide-angle X-ray scattering. This study demonstrates that the third component PC71BM can be used as a morphology regulator to regulate the morphology of BHJ or LbL active layers, thus effectively improving the performance of BHJ and LbL OSCs.

13.
Opt Express ; 31(23): 38921-38938, 2023 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-38017983

RESUMO

Focused higher-order Poincaré (HOP) beams are of particular interest because they facilitate understanding the exotic properties of structured light and their applications in classical physics and quantum information. However, generating focused HOP beams using metasurfaces is challenging. In this study, we proposed a metasurface design comprising two sets of metal nanoslits for generating coaxially focused HOP beams. The nanoslits were interleaved on equispaced alternating rings. The initial rings started at the two adjacent Fresnel zones to provide opposite propagation phases for overall elimination of the co-polarization components. With the designed hyperbolic and helical profiles of the geometric phases, the two vortices of the opposite cross-circular-polarizations were formed and selectively focused, realizing HOP beams of improved quality. Simulations and experimental results demonstrated the feasibility of the proposed metasurface design. This study is of significance in the integration of miniaturized optical devices and enriches the application areas of metasurfaces.

14.
Zootaxa ; 5306(3): 367-376, 2023 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-37518517

RESUMO

The genus Paraxantia was recorded to be distributed in south of China, previously including 11 species. After examining numerous specimens of Paraxantia, here, we first propose that the genus Paraxantia could be divided into three species groups, and describe two new species from Himalaya-Hengduan Mountains: P. angustipennis sp. nov. and P. nujiangensis sp. nov.. A key to the species group of Paraxantia, necessary illustrations and life images of Paraxantia species are presented. The distribution of Paraxantia in Himalaya-Hengduan Mountains is discussed and mapped.


Assuntos
Ortópteros , Animais , Distribuição Animal
15.
J Phys Chem Lett ; 14(20): 4842-4849, 2023 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-37194946

RESUMO

DNA alkylating agents are widely used in anticancer pharmacology. Although shown to induce cross-linking and/or methylation of DNA, how they affect the mechanical properties of DNA and activity of DNA enzymes remains to be elucidated. Here, we perform single-molecule optical tweezer experiments on DNA treated with alkylating agents, including melphalan, cisplatin, and dacarbazine. While all three drugs induce a significant increase of overstretching force and a reduction of hysteresis, suggesting stabilization of DNA against shearing forces, their effects on elasticity of DNA were quite different, with the largest change in persistence length induced by cisplatin. Furthermore, we find that these alkylating-agent-induced changes on DNA have different effects on processivity of DNA polymerase, with melphalan and cisplatin showing significantly reduced activity and dacarbazine showing little effect. Overall, our results provide new insights into the effects for these alkylating agents, which could potentially facilitate a better design of related drugs.


Assuntos
Alquilantes , Melfalan , Alquilantes/farmacologia , Melfalan/farmacologia , Cisplatino , Antineoplásicos Alquilantes/farmacologia , Dacarbazina , DNA , Análise Espectral
17.
Front Pediatr ; 11: 1095054, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37051433

RESUMO

Background: To assess the effect of megarectum on postoperative defecation of female patients with congenital rectovestibular fistula or rectoperineal fistula. Methods: From March 2013 to February 2021, 74 female patients with congenital rectovestibular fistula or rectoperineal fistula were treated. The age of patients ranged from 3 months to 1 year. Barium enema and spinal cord MRI were performed in all children. 4 patients were removed from the study because of spinal cord and sacral agenesis. Finally, 70 patients underwent one-stage anterior sagittal anorectoplasty (ASARP). Anal endoscopy and anorectal pressure measurement were performed 1 year after surgery. All patients were divided into two groups depending on the presence of megarectum (+) and (-) and observed for constipation and anal sphincter function. Results: 16 patients (4 months to 1 year) were complicated with megarectum, and 5 patients (3 months to 9 months) were without megarectum. The incision infection was seen in 3 patients. All patients were followed up for 1 year to 5 years. Fecal soiling was seen in 2 patients and constipation in 14 patients. Among 16 patients with megarectum, soiling was seen in 1 patient and the constipation in 12 patients. Among 54 patients without megarectum, soiling was seen in 1 patient and constipation in 2 patients. There was a significant difference in the incidence of postoperative constipation between the two groups (megarectum (+) 75% vs. megarectum (-) 3.7% (P < 0.05)). However, there was no significant difference in the score of anal sphincters between the two groups (P < 0.05). And there was no significant difference in anal resting pressure (P = 0.49) and length of anal high pressure area (P = 0.76). 7 patients with constipation and megarectum acquired normal anal function after the dilated rectum was resected. Conclusion: Megarectum increases the possibility of difficult postoperative defecation in the patients with congenital rectovestibular fistula or rectoperineal fistula. However, constipation was not associated with ASARP postoperative effects on sphincter function. Resection of megarectum is helpful to the improvement of constipation.

18.
Zootaxa ; 5258(5): 566-572, 2023 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-37044574

RESUMO

Previously 47 genera of the subfamily Phaneropterinae were recorded from China, not including the genus Himertula Uvarov, 1940. Here, Himertula Uvarov, 1940 is reported in China for the first time, adding a new species H. gyirongensis sp. nov., specimens of which were collected in Tibet, China. Illustrations and habitat images are provided. The distribution of Himertula species is also discussed and mapped. The types are deposited in Insect Collection of Institute of Zoology, Chinese Academy of Sciences, Beijing, China (IZCAS).


Assuntos
Ortópteros , Animais , Distribuição Animal , China , Ecossistema
19.
Environ Sci Pollut Res Int ; 30(21): 59781-59792, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37012572

RESUMO

Annular fire source is a common combustion form in fire accidents. Effects of Din/Dout (the ratio of inner to outer diameters of the floating-roof tank) on the flame morphology and plume entrainment mechanisms of annular pool fires were studied by numerical simulation. Results show, as Din/Dout increases, the area with low combustion intensity near the central axis of the pool surface gradually increases. Combined with the time-series HRR and the stoichiometric mixture fraction line of the fire plume, it reveals that the combustion of annular pool fire is dominated by non-premixed diffusion flame. The pressure near the pool outlet decreases with Din/Dout, while the plume turbulence presents an opposite trend. Based on the time-sequential plume flow and the gas-phase material distribution data, the flame merging mechanism of the annular pool fires is revealed. Furthermore, based on the similarity criterion, it verifies that the applicability of the above scaled simulation conclusions could also be extended to guide full-scale fires.


Assuntos
Incêndios , Simulação por Computador
20.
Adv Sci (Weinh) ; 10(13): e2207429, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36807708

RESUMO

RuO2 is well known as the benchmark acidic oxygen evolution reaction (OER) catalyst, but its practical application has been impeded by its limited durability. Herein, it is presented that the stability of ruthenium oxide can be significantly improved by pretrapping RuCl3 precursors within a cage compound possessing 72 aromatic rings, which leads to well carbon-coated RuOx particles (Si-RuOx @C) after calcination. The catalyst survives in 0.5 M H2 SO4 for an unprecedented period of 100 hours at 10 mA cm-2 with minimal overpotential change during OER. In contrast, RuOx prepared from similar non-tied compounds doesn't exhibit such catalytic activity, highlighting the importance of the preorganization of Ru precursors within the cage prior to calcination. In addition, the overpotential at 10 mA cm-2 in acid solution is only 220 mV, much less than that of commercial RuO2 . X-ray absorption fine structure (FT-EXAFS) reveals the Si doping through unusual Ru-Si bond, and density functional theory (DFT) calculation reveals the importance of the Ru-Si bond in enhancing both the activity and stability of the catalyst.

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