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1.
J Cardiovasc Med (Hagerstown) ; 25(8): 587-600, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-38949146

RESUMO

AIMS: To systematically evaluate the effectiveness of mobile health (mHealth) interventions on medication adherence in patients with heart failure. METHODS: The literature search was conducted in PubMed, Web of Science, the Cochrane Library databases, Embase, China National Knowledge Infrastructure (CNKI), Wanfang Database and China Scientific Journal Database (VIP). The retrieval period was from the establishment of the database to May 2023. The included studies were trials to explore the effectiveness of mHealth interventions on medication adherence in patients with heart failure. Cochrane collaboration's tool was used for assessing risk of bias in randomized controlled trials. Stata 17.0 software was used to conduct data analysis. Continuous data were expressed as standard mean differences, and dichotomous data were expressed as relative risks with 95% confidence intervals (CIs). RESULTS: A total of 13 studies and 2534 participants were included. One study was rated as Grade A, and the other 12 studies were Grade B. The results of meta-analysis indicate that mHealth interventions are effective in improving medication adherence [relative risk (RR) = 1.26, 95% CI 1.10-1.44, P < 0.05 and standard mean difference = 0.80, 95% CI 0.44-1.15, P < 0.05], and reducing readmission rates (RR = 0.63, 95% CI 0.53-0.76, P < 0.05) and mortality (RR = 0.63, 95% CI 0.43-0.94, P < 0.05) of patients with heart failure. CONCLUSION: mHealth interventions are beneficial to improve medication adherence in patients with heart failure, and could effectively reduce the readmission rates and mortality of patients in the studies. There is a need to continuously improve the professional abilities of intervention personnel, carry out teamwork, and extend intervention and follow-up time. Convenient, fast and low-cost mobile medical devices should be adopted to reduce the cost of medical treatment. Scientific and reasonable intervention content will be formulated according to evidence-based guidelines and theoretical basis to enhance patients' ability at self-management and understanding of heart failure knowledge.


Assuntos
Insuficiência Cardíaca , Adesão à Medicação , Telemedicina , Humanos , Insuficiência Cardíaca/terapia , Insuficiência Cardíaca/mortalidade , Adesão à Medicação/estatística & dados numéricos , Feminino , Masculino , Pessoa de Meia-Idade , Idoso , Resultado do Tratamento , Ensaios Clínicos Controlados Aleatórios como Assunto
2.
J Obstet Gynaecol Res ; 49(7): 1770-1777, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37231962

RESUMO

AIM: To make a bibliometric analysis on post-traumatic growth (PTG) after childbirth. METHODS: The topic advanced search strategy extracted the information from the Web of Science Core Collection. Descriptive statistics were performed using Excel, and bibliometric analysis was performed using VOSviewer. RESULTS: A total of 362 publications were published in 199 journals were obtained in the WoSCC from 1999 to 2022. Postpartum post-traumatic growth is in a trend of fluctuating growth, and the United States (N = 156) and Bar-Ilan University (N = 22) were the top contributing countries and institutions, respectively. Research hotspots mainly focus on theoretical models of PTG, postpartum post-traumatic stress disorder (PTSD) as a predictor of PTG, facilitators of PTG, and the relationship between mother-infant attachment and PTG. CONCLUSION: This bibliometric study provides a comprehensive overview of the current state of research on PTG after childbirth, an area that has received considerable scholarly attention in recent years. However, research on post-traumatic growth after childbirth is lacking, and further research is needed.


Assuntos
Crescimento Psicológico Pós-Traumático , Lactente , Feminino , Gravidez , Humanos , Parto , Parto Obstétrico , Período Pós-Parto , Bibliometria
3.
Front Plant Sci ; 14: 1144449, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36909412

RESUMO

Flavonoids are one of the most important bioactive components in litchi (Litchi chinensis Sonn.) seeds and have broad-spectrum antiviral and antitumor activities. Litchi seeds have been shown to inhibit the proliferation of cancer cells and induce apoptosis, particularly effective against breast and liver cancers. Elucidating the distribution of flavonoids is important for understanding their physiological and biochemical functions and facilitating their efficient extraction and utilization. However, the spatial distribution patterns and expression states of flavonoids in litchi seeds remain unclear. Herein, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) was used for in situ detection and imaging of the distribution of flavonoids in litchi seed tissue sections for the first time. Fifteen flavonoid ion signals, including liquiritigenin, apigenin, naringenin, luteolin, dihydrokaempferol, daidzein, quercetin, taxifolin, kaempferol, isorhamnetin, myricetin, catechin, quercetin 3-ß-d-glucoside, baicalin, and rutin, were successfully detected and imaged in situ through MALDI-MSI in the positive ion mode using 2-mercaptobenzothiazole as a matrix. The results clearly showed the heterogeneous distribution of flavonoids, indicating the potential of litchi seeds for flavonoid compound extraction. MALDI-MS-based multi-imaging enhanced the visualization of spatial distribution and expression states of flavonoids. Thus, apart from improving our understanding of the spatial distribution of flavonoids in litchi seeds, our findings also facilitate the development of MALDI-MSI-based metabolomics as a novel effective molecular imaging tool for evaluating the spatial distribution of endogenous compounds.

4.
Ergonomics ; 66(8): 1043-1056, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36165739

RESUMO

This paper examined pilots' risk-taking behavioural intentions based on the theory of planned behaviour, as well as the impact of experience on behavioural intentions in adverse weather conditions. Two hundred and seventy-three airline pilots and flying cadets were divided into two groups and asked to complete a questionnaire based on two decision-making scenarios. This questionnaire measured pilots' intentions to take risks, along with the attitude towards the behaviour, subjective norms, perceived behavioural control (PBC), risk perception, and self-identity. The results showed that attitude, subjective norm, PBC, and risk perception explained 52% of the variance in behavioural intentions. Additionally, pilots' risk-taking decisions can be influenced by experience. Inexperienced pilots had a relatively stronger intention to take risks and a more favourable attitude towards risky behaviour. Moreover, pilots were more likely to rely on their own direct experience in the decision-making process. Practitioner summary: This study examined the pilots' risk-taking intentions under adverse weather conditions using a questionnaire based on the TPB theory. Results demonstrated that the TPB model can be applied to the risk-taking scenario and that experience can influence pilots' decisions. These findings have implications for improving flight safety and lowering accident rates.


Assuntos
Intenção , Pilotos , Humanos , Teoria do Comportamento Planejado , Assunção de Riscos , Tempo (Meteorologia) , Inquéritos e Questionários , Teoria Psicológica
5.
J Obstet Gynaecol Res ; 48(11): 2946-2955, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36319197

RESUMO

BACKGROUND: Currently, most postpartum posttraumatic stress disorder (PTSD) screening scales used in China are general PTSD scales which are not compiled specifically for pregnant women and thus cannot reflect the unique needs of this population. This study aimed to translate the City Birth Trauma Scale (City BiTS) into Chinese and validate its psychometric characteristics in Chinese postpartum women. METHODS: After translation, back-translation, and expert discussion, 596 mothers at 1 to 12 months postpartum filled out the questionnaires through the Internet. The reliability and validity of the translated questionnaire were tested. RESULTS: The Cronbach's α coefficient of the Chinese version of City BiTS (City BiTS-C) was 0.889, the test-retest reliability was 0.86, and the content validity was 0.93. Exploratory factor analysis extracted two factors accounted for 63.148% of the variance. The City BiTS-C had appropriate construct validity in the Chinese culture (root mean square error of approximation [RMSEA] = 0.048, <0.05; χ2 /df = 2.666, <3). The values of the incremental fit index (IFI) and the Tucker-Lewis coefficient (TLI) were 0.990 and 0.976, which identified that the model was a good fit for the data. The values of the comparative fit index (CFI) and the normed fit index (NFI) were 0.890 and 0.873, respectively. CONCLUSIONS: The City BiTS-C is a reliable and valid measure to screening and diagnosis the postpartum PTSD among new mothers who gave birth in the past year in mainland China. IMPLICATIONS: The City BiTS-C is a short, reliable, and valid instrument that measures the symptoms of postpartum PTSD, and it is recommend for clinical screening.


Assuntos
Povo Asiático , Período Pós-Parto , Gravidez , Feminino , Humanos , Psicometria , Reprodutibilidade dos Testes , China , Inquéritos e Questionários
6.
J Immigr Minor Health ; 24(5): 1269-1280, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35000054

RESUMO

Immigrants are a special group in society, and their health is of great concern. Few studies have targeted this population in China. A cross-sectional descriptive correlational study was conducted from July to August 2018 in Hubei Province, China. Chi-square tests, Z-tests and multivariable linear regression analysis were performed to analyze the data using SPSS 24.0. A total of 1068 questionnaires were distributed. The results showed that the variables that affected the mental health of the immigrants with chronic diseases included gender, annual income, life events (L), negative emotion (NE), negative coping styles (NC) and objective support (OS) (p ≤ 0.05). Future research should focus on the physical and mental health of different immigrant groups and design effective, individualized interventions to improve the health status of immigrants, especially those with chronic diseases.


Assuntos
Emigrantes e Imigrantes , Saúde Mental , China/epidemiologia , Doença Crônica , Estudos Transversais , Humanos , Inquéritos e Questionários
7.
J Community Health Nurs ; 38(1): 48-58, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33682549

RESUMO

To evaluate the effectiveness of pelvic floor muscle training (PFMT) on perimenopausal women with pelvic floor dysfunction (PFD). A two-group longitudinal experimental design with multiple comparisons. The intervention group (n = 37) received a 3-month intervention combining Kegel and yoga exercise. The control group (n = 37) received Kegel exercise. The combined training alleviated PFD symptoms, improved life quality and increased pelvic floor muscle strength of perimenopausal women. Women with PDF symptoms can integrate PFMT and yoga exercise to promote rehabilitation and improved outcomes. Combined exercise should be taught and practiced under supervision by qualified health professionals.


Assuntos
Terapia por Exercício , Distúrbios do Assoalho Pélvico/prevenção & controle , Diafragma da Pelve/fisiopatologia , Perimenopausa , Adulto , Enfermagem em Saúde Comunitária , Feminino , Humanos , Estudos Longitudinais , Pessoa de Meia-Idade , Inquéritos e Questionários , Resultado do Tratamento
8.
Birth ; 46(2): 211-221, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30240042

RESUMO

BACKGROUND: Overweight and obesity are related to maternal and infant physical health, such as gestational diabetes, preeclampsia, and macrosomia. The purpose of this meta-analysis was to assess the effect of physical exercise on maternal and infant outcomes in overweight and obese pregnant women. METHODS: Two researchers independently searched Cochrane Library, Embase, PubMed, Web of Science, and ClinicalTrials.gov. for English-language articles based on randomized controlled trials examining physical exercise in overweight and obese pregnant women and its effect on maternal and infant outcomes. Primary outcomes were gestational weight gain and a relative risk of gestational diabetes. Secondary outcomes were gestational hypertension, preeclampsia, cesarean delivery, birthweight, large for gestational age, small for gestational age, macrosomia, and preterm birth. Risk bias was evaluated by Cochrane Collaboration's tool. The results of integration were reported as relative risks (RR), mean difference, or standard mean difference with 95% confidence intervals (CI). This meta-analysis was registered on PROSPERO on November 18, 2017, with registration number CRD42017081565. RESULTS: Thirteen studies involving 1439 participants were included. Physical exercise reduced gestational weight gain (mean difference = -1.14 kg, 95% CI = [-1.67 to -0.62], P < 0.0001) and the risk of gestational diabetes (RR = 0.71, 95% CI = [0.57-0.89], P = 0.004) in overweight and obese pregnant women. There were no significant differences in other outcomes such as gestational hypertension, preeclampsia, cesarean delivery, birthweight, large for gestational age, small for gestational age, macrosomia, and preterm birth. CONCLUSIONS: Prenatal exercise interventions reduced gestational weight gain and the risk of gestational diabetes for overweight and obese pregnant women, which reinforced the benefits of exercise during pregnancy. However, no evidence was found with respect to benefits and/or harm for infants. Consideration should be taken when interpreting these findings as a result of the relative small sample size in this meta-analysis. Further larger well-designed randomized trials may be helpful to assess the short-term and long-term effects of prenatal exercise on maternal and infant outcomes.


Assuntos
Diabetes Gestacional/prevenção & controle , Exercício Físico , Ganho de Peso na Gestação , Obesidade/terapia , Sobrepeso/terapia , Complicações na Gravidez/prevenção & controle , Feminino , Idade Gestacional , Humanos , Saúde do Lactente , Recém-Nascido , Obesidade/complicações , Sobrepeso/complicações , Gravidez , Resultado da Gravidez , Ensaios Clínicos Controlados Aleatórios como Assunto
9.
J Obstet Gynaecol Res ; 45(3): 695-704, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30393998

RESUMO

AIM: To evaluate the output of scientific publications in obstetrics and gynecology journals from Mainland China and six other countries, to compare the difference of research situation between Mainland China and the developed countries in order to measure the trend of number of publication in the field of Obstetrics and Gynecology. METHODS: Information on article amounts, impact factors (IF), citation and publication in high-impact obstetrics and gynecology journals by seven top-ranking countries between January 1, 2007 and August 31, 2017, was extracted from Web of Science databases. RESULTS: A total of 137 661 articles were published between 2007 and 2017 in the 98 obstetrics and gynecology journals. The cumulative IF and citations of articles from USA were the highest. The highest average citation was France and Mainland China ranked fourth. There were 52 631 papers published in the top 10 obstetrics and gynecology journals and the USA accounted for the majority of these papers (33 978, 64.6%), followed by England (8347, 15.9%). Articles from the USA were most often published in American Journal of Obstetrics and Gynecology (10658) and those from Mainland China were mostly published in Fertility and Sterility (809). CONCLUSION: The USA published the most articles having high IF, making the greatest contribution to the field of obstetrics and gynecology. Although the number of scientific publications from Mainland China has rapidly increased from 2007 to 2017, the quality of these publications has not been as satisfactory. It implys that Chinese current academic evaluation system should pay special attention to the quality of academic papers, instead of the number of papers published by scientists.


Assuntos
Ginecologia , Obstetrícia , Editoração , Bibliometria , China , Feminino , Humanos , Gravidez , Estados Unidos
10.
Int J Nurs Pract ; 25(1): e12707, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30456863

RESUMO

AIM: To quantitatively analyse factors related to gastrointestinal bleeding after percutaneous coronary intervention and provide evidence for the prevention of gastrointestinal bleeding. DATA SOURCES AND REVIEW METHODS: Cochrane Library, Pubmed, Embase, and Ovid databases were searched from inception to 31 May 2018; case-control and cohort studies published in English were included. The methodological quality of each study was assessed by two independent reviewers using the Newcastle-Ottawa Scale. Meta-analysis was performed using Revman version 5.3. RESULTS: A total of 16 publications yielded data about risk factors. It was found that age older than 70 years, age (per 10-year increase), female sex, baseline anaemia, history of smoking, history of using alcohol, history of peptic ulcer disease, chronic renal failure, previous bleeding, shock, congestive heart failure, acute myocardial infarction, prior use of inotropic medications, and prior use of antithrombotic medications were positively associated with gastrointestinal bleeding. Four articles yielded data about protective factors. It was found that proton-pump inhibitor and bivalirudin therapy were negatively associated with gastrointestinal bleeding after percutaneous coronary intervention. CONCLUSION: This research found risk and protective factors which can assist in effective management of this potentially fatal complication.


Assuntos
Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/prevenção & controle , Intervenção Coronária Percutânea/efeitos adversos , Humanos , Fatores de Risco
11.
PLoS One ; 13(9): e0203669, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30192881

RESUMO

The effect of soil and water conservation measures (SWCMs) is usually dependent on time. Thus the trend in reducing runoff and sediment over time is a very important theoretical problem for evaluating the effectiveness of SWCMs. Moreover, there is still a lack of comprehensive assessment of water erosion dynamics following implementing SWCMs despite their ecological significance. Therefore, the long-term impact of SWCMs on runoff and sediment and their relationships was assessed for an orchard on sloping red soil in southern China. Overland flow and erosion sediment were continuously observed for 15 years on citrus experimental plots under one of four treatments: grass strips, strip intercropping, level terrace and clean-tillage. By means of Mann-Kendall trend tests and double cumulative curves, the time series of runoff and sediment under the different treatments were analyzed. Furthermore, we linked the effect of soil conservation and the relationship between runoff and sediment variation to determine the mechanism of conservation measures on sediment reduction. The results showed that the first 4 years was the key period to prevent soil erosion for this orchard, and then the intensity of soil erosion decreased below 500 t·km-2·a-1. Considering economic costs and ecological effect, grass strips were the best protective measure for this test situation. The fitted curves of the effect of SWCMs on sediment reduction over time showed an 'L' form, but on runoff there was an approximately horizontal line. The SWCMs did not change the rainfall-runoff relationship, but did change the runoff-sediment erosion relationship. The erosion reduction mechanism of SWCMs in the early phase was a joint function of reducing runoff and changing the runoff-sediment relationship, and in the post-stable phase it worked mainly by reducing runoff. The results provide the basis for rational allocation of SWCMs considering location and time.


Assuntos
Conservação dos Recursos Hídricos , Sedimentos Geológicos/química , Solo/química , China , Chuva , Fatores de Tempo
12.
Int J Gynaecol Obstet ; 138(3): 250-255, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28602038

RESUMO

BACKGROUND: Symptoms associated with urinary incontinence (UI) frequently affect quality of life. OBJECTIVES: To assess the effects of pelvic floor muscle training (PFMT) among women with UI. SEARCH STRATEGY: The Cochrane Library, PubMed, and Web of Science databases were searched using relevant terms for all English-language studies published up to August 15, 2016. SELECTION CRITERIA: Studies that evaluated the effects of PFMT on UI symptoms, PFM function, and quality of life were included. DATA COLLECTION AND ANALYSIS: Data were screened and collected by two independent investigators. Pooled effect sizes and 95% confidence intervals (CIs) were calculated. MAIN RESULTS: Twelve studies were included, involving 763 patients. Use of PFMT increased PFM strength when measured by digital palpation and the Muscle Strength Oxford Scale (standardized mean difference [SMD] 1.18, 95% CI 0.56-1.80). The PFM pressure was increased by PFMT when measured using a perineometer (SMD 0.40, 95% CI 0.07-0.73). Finally, PFMT improved quality of life (SMD 1.67, 95% CI 0.41-2.94). CONCLUSIONS: Regular use of PFMT provided symptom relief and improved quality of life among women with UI.


Assuntos
Terapia por Exercício , Diafragma da Pelve/fisiologia , Qualidade de Vida , Incontinência Urinária/reabilitação , Feminino , Humanos , Incontinência Urinária/psicologia
13.
Huan Jing Ke Xue ; 38(10): 4178-4186, 2017 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965201

RESUMO

The development of agriculture in the red soil sloping uplands has been increasingly restricted by low water availability, high temperatures, and low fertilizer use efficiency. Subsurface flow has a significant influence on runoff generation, nutrient loss, and soil erosion. The rainfall-runoff process makes it easy for nutrients on the sloping land to enter water bodies through subsurface flow mainly in the liquid phase, which may lead to environmental problems such as eutrophication and groundwater pollution. Phosphorus as one of the common nutrients causing eutrophication is immobile in the soil because it is easily absorbed and fixed by soil particles. Thus, the principal pathway of phosphorus release from the soil is the surface flow. In some regions, sufficient and concentrated rainfall results in the surface-subsurface flow that enhances phosphorus migration. Recently, researchers have studied the migration patterns of red soil phosphorus through surface flow and the impact factors arising from these migrations, as well as the generation of subsurface flow and its influence on phosphorus outputs. However, there are relatively few investigations that have comprehensively considered the influence of both surface flow and subsurface flow on the migration of red soil phosphorus. In order to investigate the characteristics of phosphorus loss through runoff under natural rainfall, a large-scale field lysimeter experiment was conducted with three treatments i.e., grass cover (GC), litter mulch (LM), and bare land (BL) on a red soil slope land in southeast China. Phosphorus loss through surface flow, interflow at different soil layers (30 cm and 60 cm), and groundwater flow (at 105 cm depth) was observed under each natural precipitation event over a one-year period. The results showed that:① The concentrations of total P (TP) and dissoluble P (DP) in surface flow were slightly higher than those in interflow and groundwater flow; the concentrations of TP and DP showed a gradual downward trend with the increase in soil depth. The total amount of TP runoff loss was ordered as BL (1.61 kg·hm-2) > LM (1.33 kg·hm-2) > GC(0.82 kg·hm-2). ② Surface flow, interflow, and groundwater contributed to 57%, 6%, and 37%, respectively, of the phosphorus runoff loss on BL plot; surface runoff was the main pathway of phosphorus loss. Groundwater flow was the crucial route of phosphorus runoff loss once a vegetation cover was in place; groundwater flow contributed to more than 71% of the phosphorus runoff loss while the surface flow contributed less than 14%. ③ Particulate phosphorus was the primary pattern of phosphorus transport which accounted for 64%-97% of the total amount of phosphorus runoff loss. The effect of phosphorus loss through groundwater flow cannot be neglected on the red soil slope land. The loss load of phosphorus through runoff can be controlled by grass cover and litter mulch treatments, whereas the concentrations of phosphorus in runoff do not significantly reduce.

14.
Sci Rep ; 5: 16846, 2015 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-26603312

RESUMO

It is challenging to realise the perfect manipulation of water waves within a broad range of frequencies. By extending conformal transformation principles to water waves, their propagation can be controlled via gradually varying water depths, permitting the realisation of a desired refractive index profile for linear water surface waves. Wave bending, directional wave emission and wave focusing are analysed experimentally with accompanying simulations. The results demonstrate desired wave manipulations within a broad range of frequencies, confirming the accuracy and effectiveness of conformal transformation for water waves.

15.
J Environ Manage ; 133: 1-11, 2014 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-24342905

RESUMO

Lake eutrophication has become a very serious environmental problem in China. If water pollution is to be controlled and ultimately eliminated, it is essential to understand how human activities affect surface water quality. A recently developed technique using the Bayesian hierarchical linear regression model revealed the effects of land use and land cover (LULC) on stream water quality at a watershed scale. Six LULC categories combined with watershed characteristics, including size, slope, and permeability were the variables that were studied. The pollutants of concern were nutrient concentrations of total nitrogen (TN) and total phosphorus (TP), common pollutants found in eutrophication. The monthly monitoring data at 41 sites in the Xitiaoxi Watershed, China during 2009-2010 were used for model demonstration. The results showed that the relationships between LULC and stream water quality are so complicated that the effects are varied over large areas. The models suggested that urban and agricultural land are important sources of TN and TP concentrations, while rural residential land is one of the major sources of TN. Certain agricultural practices (excessive fertilizer application) result in greater concentrations of nutrients in paddy fields, artificial grasslands, and artificial woodlands. This study suggests that Bayesian hierarchical modeling is a powerful tool for examining the complicated relationships between land use and water quality on different scales, and for developing land use and water management policies.


Assuntos
Conservação dos Recursos Naturais , Modelos Teóricos , Qualidade da Água , Teorema de Bayes , China
16.
Guang Pu Xue Yu Guang Pu Fen Xi ; 31(9): 2521-4, 2011 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-22097862

RESUMO

Using a measurement system consisting of monochromators, photomultiplier tubes, piezoelectric pressure sensors and a digital oscilloscope, characteristic emissions of intermediate products OH, CH and C2 produced in the combustion reaction of methylcyclohexane were measured behind reflected shock waves in a shock tube, and ignition delay times of methylcyclohexane/ oxygen/argon were acquired. Experimental conditions cover temperatures from 1 164 to 1 566 K, pressures from 1.03 to 1.99 atm, a fuel concentration of 1.0%, and an equivalence ratio of 1.0. Combustion reaction characteristics of methylcyclohexane were obtained qualitatively by analyzing emissions from intermediate products OH, CH and C2. The measured ignition delay times agree with available experimental data and the prediction of a combustion reaction mechanism. Current work provides experimental data for constructing and validating the combustion reaction mechanism of methylcyclohexane.

17.
Guang Pu Xue Yu Guang Pu Fen Xi ; 31(2): 488-91, 2011 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-21510410

RESUMO

Using a measurement system consisting of a monochromator, a photomultiplier tube (PMT), piezoelectric pressure sensors and a digital oscilloscope, the ignition delay times of n-heptane/O2 mixture were measured behind reflected shock waves in a chemical shock tube, the onset of ignition was indicated by the steepest rise of the characteristic emission from OH radical at 306.4 nm. The experimental conditions cover temperatures from 1 170 to 1 730 K, pressures at (1.0 +/- 0.1) and (0.75 +/- 0.05) atm, and equivalence ratio of 1.0. Under these experimental conditions, the correlation formulas of ignition delay time dependence on the temperature for n-heptane have been obtained. Present results indicate that the ignition delay times of n-heptane decreases exponentially with the increase in temperatures. While temperature increases, the change rate of ignition delay time of n-heptane under the pressure of 0.75 atm is less than that of 1.0 atm. Present ignition delay data are important for constructing the kinetic model of the combustion reaction and provide an experimental criterion for validating the combustion reaction mechanism of n-heptane.

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