Experimental and analytical analysis of polarization and water transport behaviors of hydrogen alkaline membrane fuel cell

Experimental test and analytical modeling are conducted to investigate the operating behavior of an alkaline electrolyte membrane (AEM) fuel cell fed by H2/air (or O2) and explore the effect of various operating pressures on the water transfer mechanism. According to the experimental test, the cell performance is greatly improved through increasing the operating pressure gradient from anode to cathode which leads to significant liquid water permeation through the membrane. The high frequency resistance of the A901 alkaline membrane is observed to be relatively stable as the operating pressure varies based on the electrochemical impedance spectroscopy (EIS) method. Correspondingly, based on the modeling prediction, the averaged water content in the membrane electrode assembly (MEA) does not change too much which leads to the weak variation of membrane ohmic resistance. This reveals that the performance enhancement should give the credit to better electro-chemical reaction kinetics for both the anode and cathode, also prone by the EIS results. The reversion of water back diffusion direction across the membrane is also observed through analytical solution

Catalytic Decomposition of Nitrogen Oxides by Bimetallic Catalysts Synthesized by Dielectric Barrier Discharge Plasma Technology

Nitrous oxide (N2O) is a common greenhouse gas and urgent need to be contained. Direct catalytic decomposition of N2O by high activity catalyst into N2 and O2 is a low-cost and harmless method. Bimetallic catalysts show good catalytic activity in many classes of reactions, and plasma technologies, applied to prepare of catalyst, are considered to be a promising method. In our contribution, DBD cold plasma is applied to synthesize Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition. The influence of cobalt and rhodium content on N2O decomposition activity shows that the optimal amount of metal is determined as 5wt. % cobalt and 0.5wt. % rhodium loaded on Al2O3. The best working voltage is determined as 18kV. The results indicated that the Rh/Al2O3 catalysts prepared by atmospheric-pressure DBD cold plasma showed smaller size and high dispersion of Rh particles, so that the metal-support interaction and the catalytic activity are enhanced. Atmospheric-pressure DBD cold plasma is proved to be an environmentally friendly and efficient method for preparing high performance Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition

Catalytic Decomposition of Nitrogen Oxides by Bimetallic Catalysts Synthesized by Dielectric Barrier Discharge Plasma Technology

Nitrous oxide (N2O) is a common greenhouse gas and urgent need to be contained. Direct catalytic decomposition of N2O by high activity catalyst into N2 and O2 is a low-cost and harmless method. Bimetallic catalysts show good catalytic activity in many classes of reactions, and plasma technologies, applied to prepare of catalyst, are considered to be a promising method. In our contribution, DBD cold plasma is applied to synthesize Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition. The influence of cobalt and rhodium content on N2O decomposition activity shows that the optimal amount of metal is determined as 5wt. % cobalt and 0.5wt. % rhodium loaded on Al2O3. The best working voltage is determined as 18kV. The results indicated that the Rh/Al2O3 catalysts prepared by atmospheric-pressure DBD cold plasma showed smaller size and high dispersion of Rh particles, so that the metal-support interaction and the catalytic activity are enhanced. Atmospheric-pressure DBD cold plasma is proved to be an environmentally friendly and efficient method for preparing high performance Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition

Association of Common Genetic Variants in Pre-microRNAs and Neuroblastoma Susceptibility: A Two-Center Study in Chinese Children

Neuroblastoma is a commonly occurring extracranial pediatric solid tumor without defined etiology. Polymorphisms in pre-miRNAs have been demonstrated to associate with the risk of several cancers. So far, no such polymorphism has been investigated in neuroblastoma. With this in mind, we performed a two-center case-control study to assess the association of genetic variants in pre-miRNAs and neuroblastoma susceptibility in Chinese children, including 393 cases and 812 controls. We found that miR-34b/c rs4938723 T > C polymorphism was significantly associated with decreased neuroblastoma risk (TC versus TT: adjusted odds ratio [OR] = 0.51, 95% confidence interval [CI] = 0.39–0.67; TC/CC versus TT: adjusted OR = 0.62, 95% CI = 0.48–0.79). We also observed the significant association between the miR-218 rs11134527 A > G polymorphism and decreased neuroblastoma risk (AG versus AA: adjusted OR = 0.73, 95% CI = 0.56–0.96). Stratified analysis further demonstrated that the protective effect of the rs4938723 T > C polymorphism remained prominent in the subgroups, regardless of age, gender, and clinical stages. In term of sites of origin, this polymorphism significantly reduced the risk of tumors originating from the adrenal gland. We further validated the significant results using false-positive report probability analyses. Overall, the miR-34b/c rs4938723 T > C and miR-218 rs11134527 A > G polymorphisms displayed a protective role from neuroblastoma. These findings need further validation

Identifying the competencies of China’s paediatric residents: a modified Delphi method study

Purpose Standardised Training of Paediatric Resident (STPR) plays an essential role in training qualified paediatricians. Until now, China had no paediatric resident competency index system to effectively guide and evaluate the competence of paediatric residents. This study aimed to establish a competency index system for paediatric residents in China to provide a reference for improving the training system and quality of STPR.Study design and setting This study conducted two rounds of Delphi expert consultation survey among paediatric medical experts (n=16), followed by screening, revising and supplementing indicators using the boundary value method. Next, the analytic hierarchy process was used to determine the weight of indicators and finally establish a competency index system for paediatric residents.Results The results of the statistical analysis revealed a positive coefficient of 100% for both rounds of expert consultation. The expert authority coefficient values were 0.82 and 0.83, and the expert coordination coefficient test was p<0.01. After referring to experts’ opinions, a competency index system for paediatric residents with 5 primary indicators, 14 secondary indicators and 73 tertiary indicators was finally formed and the weight of each indicator was calculated. The five primary indicators were professional quality (0.3187), knowledge and skills (0.2734), communication and cooperation (0.1986), lifelong learning (0.1302), and teaching ability (0.0791).Conclusions In this study, a competency index system for paediatric residents was constructed following the characteristics and quality requirements for paediatric residents in China and is expected to significantly improve the overall level of paediatricians’ medical service quality and supply

The relationship between childhood adversities and complex posttraumatic stress symptoms: a multiple mediation model

Background: There is a growing research literature on complex posttraumatic stress disorder (CPTSD), yet studies that focused on Chinese populations are still limited. Accumulating evidence showed that adverse childhood experiences (ACEs) are associated with a higher likelihood of CPTSD symptoms, but potential mediating roles of self-kindness and self-judgement on the ACEs-CPTSD relationship remain understudied. Objective: The purpose of this study was to first examine the relationship between ACEs and CPTSD among Chinese college students, and then to test the mediating role of self-kindness and self-judgement on the ACEs-CPTSD relationship. Method: The study included 1361 college students for an online survey in May 2020. Demographic variables (e.g. age, gender, having sibling[s] or not, residence, family structure, and subjective socioeconomic status), ACEs, self-compassion (self-kindness and self-judgement subscales), and CPTSD symptoms were assessed. After controlling for demographic variables, a series of structural equation models tested the mediation hypothesis: indirect effects of self-kindness and self-judgement on the relationship between ACEs and CPTSD symptom. Results: ACEs of College students were positively associated with more severe CPTSD symptoms (posttraumatic stress disorder and disturbances in self-organization symptoms). Furthermore, these direct pathways were mediated by decreased self-kindness and increased self-judgement. Conclusions: Findings have substantial theoretical and treatment implications, including the two critical targets (i.e. lowering self-judgement and raising self-kindness) when treating complex PTSD

Using the dynamics of productivity and precipitation-use efficiency to detect state transitions in Eurasian grasslands

Using the dynamics of productivity and precipitation-use efficiency to detect state transitions in Eurasian grasslands

Functional Polymorphisms at ERCC1/XPF Genes Confer Neuroblastoma Risk in Chinese Children

Variations in nucleotide excision repair pathway genes may predispose to initiation of cancers. However, polymorphisms of ERCC1/XPF genes and neuroblastoma risk have not been investigated before. To evaluate the relevance of polymorphisms of ERCC1/XPF genes in influencing neuroblastoma susceptibility, we genotyped four polymorphisms in ERCC1/XPF genes using a Chinese population of 393 cases and 812 controls. The results showed that ERCC1 rs2298881 and rs11615 predisposed to enhanced neuroblastoma risk [CA vs. AA: adjusted odds ratio (OR) = 1.94, 95% confidence interval (CI) = 1.30–2.89, P = 0.0012; CC vs. AA: adjusted OR = 2.18, 95% CI = 1.45–3.26, P = 0.0002 for rs2298881, and AG vs. GG: adjusted OR = 1.31, 95% CI = 1.02–1.69, P = 0.038 for rs11615]. Moreover, XPF rs2276466 was also associated with increased neuroblastoma risk (GG vs. CC: adjusted OR = 1.66, 95% CI = 1.02–2.71, P = 0.043). In the combined analysis of ERCC1, we found that carriers with 2–3 risk genotypes were more likely to get risk of neuroblastoma, when compared to those with 0–1 risk genotype (adjusted OR = 1.75; 95% CI = 1.25–2.45, P = 0.0012). Our study indicates that common genetic variations in ERCC1/XPF genes predispose to neuroblastoma risk, which needs to be further validated by ongoing efforts. Keywords: Neuroblastoma, Susceptibility, ERCC1, XPF, Polymorphis

Long-term trend and interannual variability of precipitation-use efficiency in Eurasian grasslands

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