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1.
Sensors (Basel) ; 24(6)2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38544144

RESUMO

Greenhouse gas satellites can provide consistently global CO2 data which are important inputs for the top-down inverse estimation of CO2 emissions and their dynamic changes. By tracking greenhouse gas emissions, policymakers and businesses can identify areas where reductions are needed most and implement effective strategies to reduce their impact on the environment. Monitoring greenhouse gases provides valuable data for scientists studying climate change. The requirements for CO2 emissions monitoring and verification support capacity drive the payload design of future CO2 satellites. In this study, we quantitatively evaluate the performance of satellite in detecting CO2 plumes from power plants based on an improved Gaussian plume model, with focus on impacts of the satellite spatial resolution and the satellite-derived XCO2 precision under different meteorological conditions. The simulations of CO2 plumes indicate that the enhanced spatial resolution and XCO2 precision can significantly improve the detection capability of satellite, especially for small-sized power plants with emissions below 6 Mt CO2/yr. The satellite-detected maximum of XCO2 enhancement strongly varies with the wind condition. For a satellite with a XCO2 precision of 0.7 ppm and a spatial resolution of 2 km, it can recognize a power plant with emissions of 2.69 Mt CO2/yr at a wind speed of 2 m/s, while its emission needs be larger than 5.1 Mt CO2/yr if the power plant is expected to be detected at a wind speed of 4 m/s. Considering the uncertainties in the simulated wind field, the satellite-derived XCO2 measurements and the hypothesized CO2 emissions, their cumulative contribution to the overall accuracy of the satellite's ability to identify realistic enhancement in XCO2 are investigated in the future. The uncertainties of ΔXCO2 caused by the uncertainty in wind speed is more significant than those introduced from the uncertainty in wind direction. In the case of a power plant emitting 5.1 Mt CO2/yr, with the wind speed increasing from 0.5 m/s to 4 m/s, the simulated ΔXCO2 uncertainty associated with the wind field ranges from 3.75 ± 2.01 ppm to 0.46 ± 0.24 ppm and from 1.82 ± 0.95 ppm to 0.22 ± 0.11 ppm for 1 × 1 km2 and 2 × 2 km2 pixel size, respectively. Generally, even for a wind direction with a higher overall uncertainty, satellite still has a more effective capability for detecting CO2 emission on this wind direction, because there is more rapid growth for simulated maximal XCO2 enhancements than that for overall uncertainties. A designed spatial resolution of satellite better than 1 km and a XCO2 precision higher than 0.7 ppm are suggested, because the CO2 emission from small-sized power plants is much more likely be detected when the wind speed is below 3 m/s. Although spatial resolution and observed precision parameters are not sufficient to support the full design of future CO2 satellites, this study still can provide valuable insights for enhancing satellite monitoring of anthropogenic CO2 emissions.

2.
Liver Int ; 41(6): 1254-1264, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33404182

RESUMO

BACKGROUND AND AIMS: About 20% of patients receiving nucleos(t)ide analogues treatment experienced low-level viraemia (LLV), which is associated with progression of liver fibrosis and high risk of hepatocellular carcinoma. We aimed to evaluate the effectiveness and safety of switching from entecavir (ETV) to tenofovir alafenamide fumarate (TAF) in ETV-treated patients with LLV. METHODS: In this prospective study, ETV-treated patients with LLV, presented to our hospital from December 2018 to October 2019, were enrolled. Switching to TAF or continuing ETV was given. The primary effectiveness endpoint was complete virological response (CVR) at 24 weeks, and the safety endpoint was the first occurrence of any clinical adverse event during the treatment. RESULTS: Totally, 211 patients were recruited and propensity score matching (PSM) generated 75 patients in either TAF or ETV group. After PSM, baseline characteristics were balanced in two groups. After 24-week treatment, the CVR and ALT normalization in TAF group were 62.7% and 47.6%, which were higher than 9.3% and 10.5% in ETV group (OR 16.4, 95% CI 6.6-40.0, P < .001) respectively. Subgroup analysis showed that switching to TAF achieved favours CVR regardless of the status of sex, age, CHB family history, HBV DNA, HBeAg and cirrhosis, whereas alcohol consumption and diabetes mellitus might compromise the CVR of switching to TAF. Both therapies were well tolerated and had satisfying renal safety. CONCLUSIONS: For ETV-treated patients with LLV, switching to TAF is safe enough and superior compared with continuing ETV monotherapy regarding both virological and biochemical benefits.


Assuntos
Hepatite B Crônica , Adenina/análogos & derivados , Alanina , Antivirais/efeitos adversos , Guanina/análogos & derivados , Vírus da Hepatite B , Hepatite B Crônica/tratamento farmacológico , Humanos , Estudos Prospectivos , Tenofovir/análogos & derivados , Resultado do Tratamento , Viremia/tratamento farmacológico
3.
Cell Physiol Biochem ; 36(3): 1026-36, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26112332

RESUMO

BACKGROUND/AIMS: New strategies for the prevention and treatment of cirrhosis are urgently needed for improving therapeutic outcome. A role of microRNAs (miRNAs) in the pathogenesis of cirrhosis has been recently acknowledged, whereas the exact involved miRNAs as well as the associated molecular signaling pathways have not been determined. Specifically, the studies on the relationship between miR-22 and bone morphogenic protein 7 (BMP7) in the development of cirrhosis are lacking. METHODS: We examined the correlation of the levels of miR-22 and bone morphogenic protein 7 (BMP7) in the liver biopsies from patients with cirrhosis. We examined overexpression or suppression of miR-22 on BMP7 in hepatocytes. We examined the binding of miR-22 to the 3'-UTR of BMP7 mRNA. Finally, in a carbon tetrachloride (CCl4)-induced cirrhosis model in mice, we gave mice adeno-associated viruses carrying antisense of miR-22, and examined its effects on BMP7 levels and the hallmarks of cirrhosis. RESULTS: The levels of miR-22 and BMP7 in the liver biopsies from patients were strongly and inversely correlated. MiR-22 inhibited BMP7 expression in hepatocytes, through directly binding the 3'-UTR of BMP7 mRNA. Expression of antisense miR-22 significantly attenuated the levels of liver fibrosis, portal hypertension and sodium retention caused by CCl4, possibly through upregulation of BMP7. CONCLUSIONS: MiR-22 promotes the development of cirrhosis through BMP7 suppression.


Assuntos
Proteína Morfogenética Óssea 7/genética , Hipertensão Portal/genética , Cirrose Hepática/genética , Fígado/metabolismo , MicroRNAs/genética , Regiões 3' não Traduzidas , Adulto , Animais , Proteína Morfogenética Óssea 7/metabolismo , Tetracloreto de Carbono , Dependovirus/genética , Feminino , Regulação da Expressão Gênica , Genes Reporter , Vetores Genéticos/administração & dosagem , Células Hep G2 , Humanos , Hipertensão Portal/induzido quimicamente , Hipertensão Portal/patologia , Hipertensão Portal/terapia , Fígado/patologia , Cirrose Hepática/induzido quimicamente , Cirrose Hepática/patologia , Cirrose Hepática/terapia , Luciferases/genética , Luciferases/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/antagonistas & inibidores , MicroRNAs/metabolismo , Pessoa de Meia-Idade , Oligonucleotídeos Antissenso/administração & dosagem , Transdução de Sinais
4.
Zhong Nan Da Xue Xue Bao Yi Xue Ban ; 40(3): 341-4, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25832540

RESUMO

Spontaneous bacterial peritonitis (SBP) is a common complication of cirrhosis. Based on our current understanding of SBP, the most common etiologies for SBP in cirrhosis are Enterobacter and Streptococcal species. Th e Aeromonas species are ubiquitous in fresh or sea water. Aeromonas caviae is never identified as etiology in cases of SBP. A patient, who had a history of liver cirrhosis related to chronic hepatitis B virus infection for 1 year, presented with diarrhea. He had diarrhea 1 week later returned from coastal city. He was hospitalized and treated with norfloxacin after 7 days of severe symptoms, including fever, abdominal distention, and diarrhea. Analysis of the ascitic specimen revealed a white-cell count of 4.42 × 109 cells/L with 88% neutrophils. Analysis of stool specimen showed a white-cell count of 60 cells per high-power field. Th e patient started the injection of cefriaxone at a dose of 4 g/d. However, the situation was not improved. Th ree days later, stool and ascitic fluid culture showed positive for Aeromonas caviae. Antibiotic susceptibility testing revealed that imipenem, meropenem, amikacin, and cefoperazone-sulbactam were highly sensitive to the Aeromonas caviae. However, the bacilli resisted to ceftriaxone, ceftazidime, ampicillin-sulbactam, levofloxacin, and sulfamethoxazole. Ceftriaxone was then switched to imipenem. The patient was fully recovered 14 days later. Aeromonas caviae is a rare pathogen of SBP in cirrhosis. It resists to third-generation of cephalosporin and fluroquinolone, which are of frequently used dependent on clinical experience. It needs a special attention.


Assuntos
Aeromonas caviae , Infecções por Bactérias Gram-Negativas/patologia , Peritonite/microbiologia , Anti-Infecciosos , Líquido Ascítico , Humanos , Contagem de Leucócitos , Cirrose Hepática , Masculino , Testes de Sensibilidade Microbiana , Peritonite/patologia
5.
Zhonghua Gan Zang Bing Za Zhi ; 22(8): 600-3, 2014 Aug.
Artigo em Zh | MEDLINE | ID: mdl-25243961

RESUMO

OBJECTIVE: To investigate reliability of FibroScan (FS) in diagnosing size of oesophageal varices (OV) in patients with liver cirrhosis. METHODS: A total of 260 patients with liver cirrhosis were enrolled in the study. All patients underwent endoscopy to assess OV stage and FS to measure liver stiffness. Receiver operating characteristic (ROC) curves were generated to evaluate the diagnostic reliability of FS. RESULTS: The FS values according to OV stage were 20.9 ± 10.3 kPa for patients without OV, 32.2 ± 13.5 kPa for patients with mild OV, 45.6 ± 18.3 kPa for patients with moderate OV, and 55.1 ± 15.6 kPa for patients with severe OV. Significant differences were found among the groups (P < 0.001) as well as between any two groups (t=6.574, 10.533, 13.247, 4.719, 7.072 and 2.171, P less than 0.05 respectively). ROC curves of FS for the diagnoses of patients with various OV stages showed the following:with vs. without OV, 0.824 (95% CI:77.5% to 87.4%); less than moderate vs. more than moderate OV, 0.849 (95% CI:79.6% to 90.2%); and less than severe vs. severe OV, 0.871 (95% CI:81.1% to 93.0%); the corresponding FS cut-off values were 22.8 kPa, 30.6 kPa, and 34.6 kPa. CONCLUSION: Liver stiffness measurement by FibroScan allows prediction of the oesophageal varices stage in patients with liver cirrhosis.


Assuntos
Técnicas de Imagem por Elasticidade , Varizes Esofágicas e Gástricas/diagnóstico , Cirrose Hepática/diagnóstico , Adulto , Varizes Esofágicas e Gástricas/etiologia , Feminino , Humanos , Cirrose Hepática/complicações , Masculino , Pessoa de Meia-Idade
6.
iScience ; 27(4): 109516, 2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38591004

RESUMO

The recent surge in dam construction has sparked debates regarding their contribution to carbon neutrality and food security, focusing on trade-offs between production benefits and ecological drawbacks. However, how dams affect carbon emissions and land cover changes, including their spatial differentiations, remains unclear. We quantified spatiotemporal variations in carbon emissions and storage of 137 large dams in China from 1992 to 2020, resulting from land cover change in potentially affected areas. We observed a lesser increase in carbon emissions and a more pronounced increase in carbon storage driven by forest conservation and regeneration within dam-affected areas compared to unaffected areas. Additionally, we noticed an increased grain yield in nearby areas potentially due to increased water availability. Our findings highlight the importance of considering land cover change when assessing carbon neutrality or grain yield at regional and national scales. This study provides useful insights into optimizing dam locations to mitigate future carbon emissions effectively.

7.
Poult Sci ; 103(9): 103931, 2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38972281

RESUMO

Hybrid breeding has proven to enhance meat quality and is extensively utilized in goose breeding. Nevertheless, there is a paucity of research investigating the molecular mechanisms that underlie the meat quality of hybrid geese. In this study, we employed the Sichuan White Goose as the maternal line for hybridization with the Zhedong White Goose and Tianfu Meat Goose P3 line. We assessed the growth and slaughter meat quality performance of 10-wk-old hybrid offspring in comparison to Sichuan white goose purebred offspring. The results indicate that hybrid geese have significantly improved performance in growth and slaughter meat quality. Furthermore, we conducted a comprehensive analysis of the chest muscles of hybrid offspring through transcriptomics and metabolomics to unravel the effects of hybrid breeding on growth and meat quality. A total of 673 differentially expressed genes (DEGs), and 93 differentially expressed metabolites were identified. The joint analysis highlighted the significant enrichment of DEGs AMPD1, AMPD3, RRM2, ENTPD3, and the metabolite UMP in the nucleotide metabolism pathway. These findings underscore the crucial role of these genetic and metabolic factors in regulating muscle growth and meat quality in hybrid populations.

8.
Heliyon ; 9(11): e22161, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38034614

RESUMO

Employees' green innovation behavior is a key factor in enterprises' promotion of green development strategies. Combining social information processing and social exchange theory, this article considers workers' green organizational commitment (GOC) as a mediating construct and knowledge sharing as a moderating construct and establishes a model of the influence of green human resource management (GHRM) on workers' green innovation conduct in company settings. An empirical analysis of 436 employees from 28 high-tech enterprises in Fujian Province shows that GHRM has a positive significant bearing on workers' green innovation conduct. Employees' GOC has a positive mediating influence on the interaction between GHRM and employees' green innovation conduct. Employees' knowledge sharing moderates positively the interaction between green organizational commitment and green innovation behavior and moderates the mediating effect of green organizational commitment. Therefore, we propose stimulating employees' green innovation behavior by implementing green GHRM, focusing on green demand and creating a knowledge-sharing atmosphere.

9.
Front Psychol ; 13: 788694, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35432134

RESUMO

Based on the regret regulation theory and entrepreneurial cognition theory, this study aims to investigate the relationship between entrepreneurs' anticipated regret and entrepreneurial persistence through the mediator of entrepreneurial cognition. To that end, we distributed surveys to entrepreneurs who were supported by the "Xing Chuang Tian Di" project and used 248 questionnaire data to examine the hypotheses. The results show that entrepreneurs' anticipated regret has a significant and direct impact on entrepreneurial persistence. Also, entrepreneurship cognition plays a mediating role between anticipated regret and entrepreneurial persistence. In addition, the entrepreneurial environment plays a positive role in moderating the relationship between anticipated regret and entrepreneurial persistence.

10.
R Soc Open Sci ; 9(1): 211208, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35116149

RESUMO

Slanted axial-flow pump devices are widely applied in urban water supply, irrigation and drainage engineering fields. The second law of thermodynamics is applied to investigate the flow loss characteristics of the 30° slanted axial-flow pump model according to the flow loss analysis method of entropy production theory, so that the hydraulic loss characteristics can be revealed in internal flow process of the slanted axial-flow pump. The three-dimensional numerical simulation of the whole flow conduit in slanted axial-flow pump was conducted and the entropy production increased in the flow process was calculated. The location and distribution characteristics of the flow loss of the pump were qualitatively analysed. The results show that the entropy production in impeller is the highest among the pump components. With the increase of flow rate, the proportion of the entropy production in impeller in total value of the pump device increases continuously. The wall entropy production of impeller, guide vane and outlet conduit are lower than the mainstream entropy production, and the mainstream entropy production occupies the dominant position. As the flow rate grows, the proportion of turbulent dissipation entropy production decreases, and the proportion of wall dissipation entropy production increases. At 0.8Q bep, the proportion of turbulent dissipation entropy production is close to 74%, which is about 2.8 times that of wall entropy production. Under 1.2Q bep condition, the proportion of turbulent dissipation entropy production is just 5.5% higher than that of wall dissipation entropy production.

11.
Front Optoelectron ; 14(4): 513-521, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36637759

RESUMO

In this paper, we proposed a quality of transmission (QoT) prediction technique for the quality of service (QoS) link setup based on machine learning classifiers, with synthetic data generated using the transmission equations instead of the Gaussian noise (GN) model. The proposed technique uses some link and signal characteristics as input features. The bit error rate (BER) of the signals was compared with the forward error correction threshold BER, and the comparison results were employed as labels. The transmission equations approach is a better alternative to the GN model (or other similar margin-based models) in the absence of real data (i.e., at the deployment stage of a network) or the case that real data are scarce (i.e., for enriching the dataset/reducing probing lightpaths); furthermore, the three classifiers trained using the data of the transmission equations are more reliable and practical than those trained using the data of the GN model. Meanwhile, we noted that the priority of the three classifiers should be support vector machine (SVM) >K nearest neighbor (KNN) > logistic regression (LR) as shown in the results obtained by the transmission equations, instead of SVM > LR > KNN as in the results of the GN model.

12.
Front Pharmacol ; 12: 734090, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34483945

RESUMO

Currently, there are no satisfactory noninvasive methods for the diagnosis of fibrosis in patients with chronic drug-induced liver injury (DILI). Our goal was to develop an algorithm to improve the diagnostic accuracy of significant fibrosis in this population. In the present study, we retrospectively investigated the biochemical and pathological characteristics of consecutive patients with biopsy-proven chronic DILI, who presented at our hospital from January 2013 to December 2017. A noninvasive algorithm was developed by using multivariate logistic regression, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA) to diagnose significant fibrosis in the training cohort, and the algorithm was subsequently validated in the validation cohort. Totally, 1,130 patients were enrolled and randomly assigned into a training cohort (n = 848) and a validation cohort (n = 282). Based on the multivariate analysis, LSM, CHE, and APRI were independently associated with significant fibrosis. A novel algorithm, LAC, was identified with the AUROC of 0.81, which was significantly higher than LSM (AUROC 0.78), CHE (AUROC 0.73), and APRI (AUROC 0.68), alone. The best cutoff value of LAC in the training cohort was 5.4. When the LAC score was used to diagnose advanced fibrosis and cirrhosis stages, the optimal cutoff values were 6.2 and 6.7, respectively, and the AUROC values were 0.84 and 0.90 in the training cohort and 0.81 and 0.83 in the validation cohort. This study proved that the LAC score can contribute to the accurate assessment of high-risk disease progression and the establishment of optimal treatment strategies for patients with chronic DILI.

13.
Remote Sens (Basel) ; 11(2)2019 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32021701

RESUMO

In urban environments, aerosol distributions may change rapidly due to building and transport infrastructure and human population density variations. The recent availability of medium resolution Landsat-8 and Sentinel-2 satellite data provide the opportunity for aerosol optical depth (AOD) estimation at higher spatial resolution than provided by other satellites. A year of 30 m Landsat-8 and 10 m Sentinel-2A AOD data retrieved using the Land Surface Reflectance Code (LaSRC) were compared with coincident ground-based Aerosol Robotic Network (AERONET) Version 3 AOD data for 20 Chinese cities. Stringent selection criteria were used to select contemporaneous data - only satellite and AERONET data acquired within 10 minutes were considered. The average satellite retrieved AOD over a 1470 m × 1470 m window centered on each AERONET site was derived to capture fine scale urban AOD variations. AERONET Level 1.5 (cloud-screened) and Level 2.0 (cloud-screened and also quality assured) data were considered. For the 20 urban AERONET sites in 2016 there were 106 (Level 1.5) and 67 (Level 2.0) Landsat-8 AERONET AOD contemporaneous data pairs, and 118 (Level 1.5) and 89 (Level 2.0) Sentinel-2A AOD data pairs. The greatest AOD values (>1.5) occurred in Beijing, suggesting that the Chinese capital was one of the most polluted cities in China in 2016. The LaSRC Landsat-8 and Sentinel-2A AOD retrievals agreed well with the AERONET AOD data (linear regression slopes > 0.96; coefficient of determination r2 > 0.90; root mean square deviation < 0.175) and demonstrate that the LaSRC is an effective and applicable medium resolution AOD retrieval algorithm over urban environments. The Sentinel-2A AOD retrievals had better accuracy than the Landsat-8 AOD retrievals, which is consistent with previously published research. The implications of the research and the potential for urban aerosol monitoring by combining the freely available Landsat-8 and Sentinel-2 satellite data are discussed.

14.
Science ; 381(6659): 740-741, 2023 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-37590368
15.
Science ; 379(6632): 547, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36758077
16.
Nanoscale Res Lett ; 12(1): 144, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28235379

RESUMO

The design of noble-metal-free catalysts for oxygen reduction reaction (ORR) is very important to the commercialization of fuel cells. Here, we use a Co-modified montmorillonite (Co-MMT) as a flat template to prepare Co- and N-doped nanocarbon ORR catalysts derived from carbonization of polyaniline at controlled temperatures. The use of flat template can hinder the agglomeration of polyaniline during pyrolysis process and optimize the N-rich active site density on the surface. The addition of transition metal Co in the flat MMT template can largely promote the formation of Co-N sites in prepared catalyst, facilitating the effective improvement of catalytic activity towards the ORR with a direct four-electron transfer pathway. The excellent ORR activity may be mainly attributed to high contents of graphitic N, pyridinic-N, and Co-N configurations. This study opens a new way to rationally design cheap and active ORR catalysts by using simple flat compound as a direct template.

17.
Materials (Basel) ; 10(5)2017 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-28772920

RESUMO

The great challenge of boosting the oxygen reduction reaction (ORR) activity of non-noble-metal electrocatalysts is how to achieve effective exposure and full utilization of nitrogen-rich active sites. To realize the goals of high utilization of active sites and fast electron transport, here we report a new strategy for synthesis of an iron and nitrogen co-doped carbon nanolayers-wrapped multi-walled carbon nanotubes as ORR electrocatalyst (N-C@CNT-Fe) via using partially carbonized hemoglobin as a single-source precursor. The onset and half-wave potentials for ORR of N-C@CNT-Fe are only 45 and 54 mV lower than those on a commercial Pt/C (20 wt.% Pt) catalyst, respectively. Besides, this catalyst prepared in this work has been confirmed to follow a four-electron reaction mechanism in ORR process, and also displays ultra-high electrochemical cycling stability in both acidic and alkaline electrolytes. The enhancement of ORR activity can be not only attributed to full exposure and utilization of active site structures, but also can be resulted from the improvement of electrical conductivity owing to the introduction of CNT support. The analysis of X-ray photoelectric spectroscopy shows that both Fe-N and graphitic-N species may be the ORR active site structures of the prepared catalyst. Our study can provide a valuable idea for effective improvement of the electrocatalytic activity of non-noble-metal ORR catalysts.

18.
Nanoscale Res Lett ; 12(1): 595, 2017 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-29149397

RESUMO

Large-scale production of active and stable porous carbon catalysts for oxygen reduction reaction (ORR) from protein-rich biomass became a hot topic in fuel cell technology. Here, we report a facile strategy for synthesis of nitrogen-doped porous nanocarbons by means of a simple two-step pyrolysis process combined with the activation of zinc chloride and acid-treatment process, in which kidney bean via low-temperature carbonization was preferentially adopted as the only carbon-nitrogen sources. The results show that this carbon material exhibits excellent ORR electrocatalytic activity, and higher durability and methanol-tolerant property compared to the state-of-the-art Pt/C catalyst for the ORR, which can be mainly attributed to high graphitic-nitrogen content, high specific surface area, and porous characteristics. Our results can encourage the synthesis of high-performance carbon-based ORR electrocatalysts derived from widely-existed natural biomass.

19.
Sci Rep ; 6: 27905, 2016 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-27291688

RESUMO

Selecting appropriate initial values is critical for parameter estimation in nonlinear photosynthetic light response models. Failed convergence often occurs due to wrongly selected initial values when using currently available methods, especially the kind of local optimization. There are no reliable methods that can resolve the conundrum of selecting appropriate initial values. After comparing the performance of the Levenberg-Marquardt algorithm and other three algorithms for global optimization, we develop a general method for parameter estimation in four photosynthetic light response models, based on the use of Differential Evolution (DE). The new method was shown to successfully provide good fits (R(2) > 0.98) and robust parameter estimates for 42 datasets collected for 21 plant species under the same initial values. It suggests that the DE algorithm can efficiently resolve the issue of hyper initial-value sensitivity when using local optimization methods. Therefore, the DE method can be applied to fit the light-response curves of various species without considering the initial values.


Assuntos
Luz , Modelos Biológicos , Fotossíntese/efeitos da radiação , Algoritmos , Plantas/metabolismo
20.
Nanoscale Res Lett ; 11(1): 268, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27225424

RESUMO

So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.

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