The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry (PIV). Velocity compo...The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry (PIV). Velocity compo- nents, fluctuation velocity, Reynolds stress and recirculation zone length are obtained, respectively. Influences of geometric parameter of primary hole, arrangement of primary hole, inlet air temperature, first-stage swirler an- gle and fuel/air ratio on flow field are investigated, respectively. The experimental results reveal that the primary recirculation zone lengths of combustion flow field are shorter than those of cold flow field, and the primary reeir- culation zone lengths decrease with the increase of inlet air temperature and fuel/air ratio. The change of the geo- metric parameter of primary hole casts an important influence on the swirler flow field in two-stage swirler com- bustor.展开更多
The key of the direct method of determining coalbed gas content is how to shorten the coal core exposure time in the sampling progress and reduce measuring error of gas content which comes from the calculation of losi...The key of the direct method of determining coalbed gas content is how to shorten the coal core exposure time in the sampling progress and reduce measuring error of gas content which comes from the calculation of losing gas content. The coring tests were carried out in No.24 drilling field of 715 floor gateway in Qinan Coal Mine by using traditional drill core bar- rel sampler and self-designed reversion seal coring equipment. The losing gas content was calculated by power functional method, and the gas content of two coring methods was determined, respectively. Results show that, compared with traditional drill core barrel sampling, the newly seal coring equipment can significantly shorten the coal core exposure time, the 30 min desorption gas content increases obviously, the calculation of losing gas content reduces by 56.99%, the desorption gas content in normal atmosphere increases by 113.24%, and the determining value of gas content increases by 10.06%. The new technol- ogy has much higher accuracy, and it is worthwhile to be popularized.展开更多
AIM: To investigate the frequency of gastroen-terological diseases in the etiology and the efficacy of proton pump inhibitors (PPIs) in the treatment of cardiac syndrome X (CSX) as a subform of non-cardiac chest pain ...AIM: To investigate the frequency of gastroen-terological diseases in the etiology and the efficacy of proton pump inhibitors (PPIs) in the treatment of cardiac syndrome X (CSX) as a subform of non-cardiac chest pain (NCCP). METHODS: We investigated 114 patients with CSX using symptom questionnaires. A subgroup of these patients were investigated regarding upper gastrointestinal disorders (GIs) and treated with PPI. Patients not willing to participate in investigation and treatment served as control group. RESULTS: Thirty-six patients denied any residual symptoms and were not further evaluated. After informed consent in 27 of the remaining 78 patients, we determined the prevalence of disorders of the upper GI tract and quantifi ed the effect of treatment with pantoprazole. We found a high prevalence of gastroenterological pathologies (26/27 patients, 97%)with gastritis, gastroesophageal reflux disease (GERD) and acid reflux as the most common associated disorders. If treated according to the study protocol, these patients showed a significant improvement in the symptom score. Patients treated by primary care physicians, not according to the study protocol had a minor response to treatment (n = 19, -43%), while patients not treated at all (n = 26) had no improvement of symptoms (-0%). CONCLUSION: Disorders of the upper GI tract are a frequent origin of CSX in a German population and can be treated with pantoprazole if given for a longer period.展开更多
With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic (TEM) method is f...With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic (TEM) method is favorable for prospecting conductive layers because of the coupling relationship between its field structure and formation. However, the shielding effect of conductive overburden would not only require a longer observation time when prospecting the same depth but also weaken the anomalous response of underlying layers. Through direct time domain numerical simulation and horizontal layered earth forward modeling, this paper estimates the length of observation time required to prospect the target, and the distinguishable criterion of multilayer water-filled goal is presented with observation error according to the effect of noise on observation data. The observed emf curves from Dazigou Coal Mine, Shanxi Province can distinguish multilayer water-filled goaf. In quantitative inversion interpretation of observed curves, using electric logging data as initial parameters restrains the equivalence caused by coal formation thin layers. The deduced three-layer and two-layer water-filled goals are confirmed by the drilling hole. The result suggests that when observation time is long enough and with the anomalous situation of underlying layers being greater than the observation error, the use of the central loop TEM method to orosoect a multilaver water-filled goaf is feasible.展开更多
Objective To study prognostic characteristics of cardiac troponin I (cTnI) elevation in acute ischemic stroke. Methods We retrospectively studied patients (n = 248) with acute ischemic stroke, acute ST-segment ele...Objective To study prognostic characteristics of cardiac troponin I (cTnI) elevation in acute ischemic stroke. Methods We retrospectively studied patients (n = 248) with acute ischemic stroke, acute ST-segment elevation myocardial infarction, and acute non-ST-elevation myocardial infarction who were treated between January 2013 and October 2015. Baseline demographic data and changes in cTnI levels among these three groups were compared. Patients with acute ischemic stroke were assigned to either the cTnI elevation group (cTnI 〉 0.034 ng/mL) or the no cTnI elevation group (cTnI ≤ 0.034 ng/mL). Logistic regression analysis was used to identify risk factors associated with elevated serum cTnI in patients with acute ischemic stroke. Moreover, the duration of hospital stay and incidence of major cardiovascular outcomes were compared in patients with acute ischemic stroke, with or without elevated cTnI. Results In this study population of patients with acute ischemic stroke (n = 178), acute ST-segment elevation myocardial infarction (n = 35), and acute non-ST-elevation myocardial infarction (n = 35), patients with acute ischemic stroke with elevated cTnI comprised 18.54% of subjects. Patients with elevated cTnI were older and more likely to have a history of hypertension. In addition, these patients had higher levels of inflammatory markers, reduced renal functions, increased D-dimer levels, higher NIH stroke scores, and lower left ventricular ejection fractions. Logistic regression analysis showed that both percentage of neutrophil and NIH stroke scores were elevated; estimated glomerular filtration rate and left ventricular ejection fraction were decreased in patients with acute ischemic stroke who had elevated cTnI, and they had more frequent major cardiovascular events during hospital stay. Conclusion Elevated cTnI detected in patients with acute ischemic stroke, indicated a greater likelihood of poor short-term prognosis during hospital stay.展开更多
Atherosclerosis and its related cardiovascular disease is the most common cause of morbidity and mortality in the Western world. The roots of this disease may lie, in part, in dietary and lifestyle behaviors, indicati...Atherosclerosis and its related cardiovascular disease is the most common cause of morbidity and mortality in the Western world. The roots of this disease may lie, in part, in dietary and lifestyle behaviors, indicating that modifica- tion of these behaviors may lead to profound improvements.展开更多
The leaching behavior of Tunceli malachite mineral was investigated in nitric acid solutions by two steps to evaluate the effect of various experimental parameters.In the first step,the optimal conditions for the leac...The leaching behavior of Tunceli malachite mineral was investigated in nitric acid solutions by two steps to evaluate the effect of various experimental parameters.In the first step,the optimal conditions for the leaching process were determined,while in the second step,a kinetic evaluation for the process was performed.In the optimization experiments,the concentration of nitric acid,temperature,stirring speed,and solid-to-liquid ratio were selected as the independent variables,and the central composite design method(CCD)was applied to the experimental data.At the end of the experiments,the optimal values for the concentration of nitric acid,temperature,solid-to-liquid ratio and stirring speed were determined to be 0.5 mol/L,50℃,0.004 g/m L and 500 r/min,respectively.Under the optimal conditions,the leaching rate was found to be 99%for 120 min of reaction time.In the kinetic evaluation tests,the effects of the concentration of nitric acid,temperature,stirring speed,solid-to-liquid ratio and particle size on the leaching rate of copper from malachite were investigated.In these tests,it was determined that the leaching rate increased with the increase in the temperature,acid concentration and stirring speed,and with the decrease in the particle size and solid-to-liquid ratio.In consequence of the kinetic analysis,it was observed that the leaching kinetics followed the mixed kinetic model,and a mathematical model for the leaching process was introduced.The activation energy for this process was calculated to be 36.23 k J/mol.展开更多
The noise level of coal face by full-mechanized coal winning technology was measured in a coal mine. And then it was analyzed and evaluated using environment science, ergonomics and fussy mathematics analysis. Basis o...The noise level of coal face by full-mechanized coal winning technology was measured in a coal mine. And then it was analyzed and evaluated using environment science, ergonomics and fussy mathematics analysis. Basis of the statistics and analysis of the measured noise level some measures, such as applying the new materials and improving the construction of the equipment, were carried out. The resuts show that they can reduce the noise level, improve the working environment and enhance the work efficiency.展开更多
Using the radius of gyration from fractal theory, this paper describes the calculation of fractal dimensions for the four tiers of central places in the Jilin Central Urban Agglomeration(JCUA), Jilin Province, China a...Using the radius of gyration from fractal theory, this paper describes the calculation of fractal dimensions for the four tiers of central places in the Jilin Central Urban Agglomeration(JCUA), Jilin Province, China and the structural characteristics of each tier: 1) the 1st tier central place, Changchun Proper(not including Shuangyang District), provides the most service functions and has the most stable primate position; 2) the 2nd tier central places, Jilin Proper, Siping Proper, Liaoyuan Proper and Songyuan Proper have unclear statuses and do not provide certain functions; 3) the 3rd tier central places comprise 23 county-level cities, counties and urban districts(including Shuangyang District of Changchun), exhibiting a dense spatial structure that agrees with theory; 4) the 4th tier contains the largest number of central places(248 designated towns), but they are loosely distributed. In this study, a spatial image of the JCUA was created, based on vectorized data of the urban settlement distribution, which was then modified and abstracted to create a hexagonal network covering the JCUA. Compared to the traditional central place model, the modified spatial image conforms to the K = 3 principle. In reality, however, the growth of some 3rd tier central places should be increased with the cities being upgraded to the 2nd tier so as to overcome that tier′s functional deficiency. The loose distribution in the 4th tier should also be changed. This apparent anomaly can be explained by the fact that the classic hexagon model used to describe the way market areas layout does not exist in the real world. However, this should not be viewed as an obstacle to using central place theory. If its assumptions are properly applied, it can still assist research into the spatial structure of regions.展开更多
Objective To investigate whether coronary artery revascularization therapies (CART), including percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), can improve the in-hospital and...Objective To investigate whether coronary artery revascularization therapies (CART), including percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), can improve the in-hospital and long-term outcomes for acute myocardial infarction (AMI) patients with prior ischemic stroke (IS). Methods A total of 387 AMI patients with prior IS were enrolled consecutively from January 15, 2005 to December 24, 2011 in this cohort study. All patients were categorized into the CART group (n = 204) or the conservative medications (CM) group (n = 183). In-hospital cardiocerebral events and long-term mortality of the two groups after an average follow-up of 36 months were recorded by Kaplan-Meier survival curves and compared by Logistic regression and the Cox regression model. Results The CART patients were younger (66.5 ± 9.7 years vs. 71.7 ± 9.7 years, P 〈 0.01), had less non-ST segment elevation myocardial infarction (11.8% vs. 20.8%, P = 0.016) and more multiple-vascular coronary lesions (50% vs. 69.4%, P = 0.031). The hospitalization incidence of cardiocerebral events in the CART group was 9.3% while 26.2% in the CM group (P 〈 0.01). CART significantly reduced the risk of in-hospital cardiocerebral events by 65% [adjusted odds ratio (OR) = 0.35, 95% CI: 0.13-0.92]. By the end of follow-up, 57 cases (41.6%) died in CM group (n = 137) and 24 cases (12.2%) died in CART group (n = 197). Cox regression indicated that CART decreased the long-term mortality by 72% [adjusted hazard ratio (HR) = 0.28, 95% CI: 0.064).46], while categorical analysis indicated no s{gnificant dif- ference between PCI and CABG. Conclusions CART has a significant effect on improving the in-hospital and long-term prognoses for AMI patients with prior IS.展开更多
The study investigates the nonlinear heart rate variability indices in different seasons and their dependence on current meteorological factors. The study included 61 relatively healthy student volunteers, their age w...The study investigates the nonlinear heart rate variability indices in different seasons and their dependence on current meteorological factors. The study included 61 relatively healthy student volunteers, their age were 19-23 and they were examined repeatedly in different seasons. The HRV (heart rate variability) recording was performed with the use of the hardware-software complex "Varikard 2.51" Nonlinear HRV indices were calculated by means of the Kubios HRV 2.1. The following indicators: SD1, SD2, SD1/SD2, D2, DFA, SampEn and quantitative indicators of recurrence analysis (RQA )---Lmean, Lmax, REC, DET, ShanEn had been analyzed. Statistical analysis was performed using the Statistica 6.0. For the detection of between-group differences were used Repeated Measures ANOVA, and the dependence of nonlinear HRV indices on meteorological was analyzed with the use of multiple non-linear regression. The investigation showed a relative increase in SampEn and the reduction of al in winter and spring seasons, strengthening relationships SampEn correlation with other indicators in the winter season as well as the dependence SampEn on meteorological factors in summer. The detected changes can be considered as the realization of adaptive response of a healthy body.展开更多
Background The neutrophil-to-lymphocyte (N/L) ratio has been associated with poor prognosis in patients with heart failure, but it has not been compared with N-terminal pro-brain natriuretic peptide (NT-proBNP) in...Background The neutrophil-to-lymphocyte (N/L) ratio has been associated with poor prognosis in patients with heart failure, but it has not been compared with N-terminal pro-brain natriuretic peptide (NT-proBNP) in elderly patients with chronic heart failure (CHF). We sought to make this comparison. Methods A total of 1355 elderly patients with CHF were analyzed. A multivariate logistic regression model was used to analyze the variables associated with atrial fibrillation (AF). Cox regression analysis was used to assess the multivariable rela- tionship between the N/L ratio, NT-proBNP level, and subsequent major cardiovascular events (MCE). Results In the multiple logistic regression analysis, the N/L ratio was demonstrated as a risk factor for AF in elderly patients with CHF [odds ratio (OR): 1.079, 95% confi- dence interval (CI): 1.027-1.134, P = 0.003]. The median follow-up period was 18 months. In a multivariable model using tertiles of both variables, the highest tertile of the N/L ratio was significantly associated with MCE [hazard ratio (HR): 1.407, 95% CI: 1.098-1.802, P = 0.007] compared with the lowest tertile. Similarly, the highest NT-proBNP tertile was also significantly associated with MCE (HR: 1.461, 95% CI: 1.104-1.934, P- 0.008). Conclusions In elderly patients with CHF, the N/L ratio is one of the important risk factors for AF and it is an inexpensive and readily available marker with similar independent prognostic power to NT-proBNP. The risk of MCE increases 1.407-fold when the N/L ratio is elevated to the highest tertile.展开更多
Objective: This study aimed to explore the effects of Chinese patent medicine(CPM) in reducing the incidence of major adverse cardiovascular events(MACE) in patients with coronary heart disease(CHD) angina pectoris an...Objective: This study aimed to explore the effects of Chinese patent medicine(CPM) in reducing the incidence of major adverse cardiovascular events(MACE) in patients with coronary heart disease(CHD) angina pectoris and improving clinical effectiveness and provide evidence for its use as clinical adjuvant therapy.Methods: Twenty-eight thousand five hundred and seventeen patients hospitalized with CHD angina pectoris from 6 hospitals were divided into CPM group(n = 11,374) and non-CPM group(n = 17,143) to evaluate the incidence of MACE, including myocardial infarction, percutaneous coronary intervention, and coronary artery bypass grafting.Results: The incidence of MACE in the CPM group was lower than that in the non-CPM group. CPM therapy was an independent protective factor that reduced the overall risk of MACE [adjusted hazard ratio = 0.40, 95% confidence interval(0.33;0.49)]. Patients in the CPM group who received one, two, or three types of CPM could benefit from adjuvant treatment with CPM, and taking more types of CPM was associated with a lower risk of MACE. In addition, the male population was better than the female population at taking CPM, and middle-aged people aged 55 to 64 were more suited to take CPM based on Western medicine.Conclusions: The use of CPM as adjuvant therapy can decrease the occurrence of MACE in patients with CHD angina pectoris,especially in men and middle-aged people, and the drug treatment plan should be optimized accordingly. However, this conclusion needs further verification by prospective cohort studies in the future.展开更多
A cylindrical coordinate measuring machine for the detection of large-size rotational parts is introduced. The measuring machine can simultaneously measure the geometrical dimensions, form and position errors of the i...A cylindrical coordinate measuring machine for the detection of large-size rotational parts is introduced. The measuring machine can simultaneously measure the geometrical dimensions, form and position errors of the inner and outer surfaces. Since the maximum length of the workpiece can reach 2 000 mm , it is difficult to be clamped and adjusted and easy to produce clamping error. The eccentricity can be up to 1.5 mm, which has an interaction effect with the probe mounting offset. We mainly study the probe offset of the measuring machine and the influence of the workpiece clamping error on the measurement. A method of controlling the offset of the measuring probe is proposed. The effect of the clamping error is eliminated through the space coordinate transformation of the workpiece axis, and the axis is fitted by the least square method. Finally, a common fixture can be realized to meet the clamping requirements of the workpiece.展开更多
基金Supported by the National Natural Science Foundation of China(50906040)the Nanjing University of Aeronautics and Astronautics Research Funding(NZ2012107,NS2010052)~~
文摘The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry (PIV). Velocity compo- nents, fluctuation velocity, Reynolds stress and recirculation zone length are obtained, respectively. Influences of geometric parameter of primary hole, arrangement of primary hole, inlet air temperature, first-stage swirler an- gle and fuel/air ratio on flow field are investigated, respectively. The experimental results reveal that the primary recirculation zone lengths of combustion flow field are shorter than those of cold flow field, and the primary reeir- culation zone lengths decrease with the increase of inlet air temperature and fuel/air ratio. The change of the geo- metric parameter of primary hole casts an important influence on the swirler flow field in two-stage swirler com- bustor.
文摘The key of the direct method of determining coalbed gas content is how to shorten the coal core exposure time in the sampling progress and reduce measuring error of gas content which comes from the calculation of losing gas content. The coring tests were carried out in No.24 drilling field of 715 floor gateway in Qinan Coal Mine by using traditional drill core bar- rel sampler and self-designed reversion seal coring equipment. The losing gas content was calculated by power functional method, and the gas content of two coring methods was determined, respectively. Results show that, compared with traditional drill core barrel sampling, the newly seal coring equipment can significantly shorten the coal core exposure time, the 30 min desorption gas content increases obviously, the calculation of losing gas content reduces by 56.99%, the desorption gas content in normal atmosphere increases by 113.24%, and the determining value of gas content increases by 10.06%. The new technol- ogy has much higher accuracy, and it is worthwhile to be popularized.
文摘AIM: To investigate the frequency of gastroen-terological diseases in the etiology and the efficacy of proton pump inhibitors (PPIs) in the treatment of cardiac syndrome X (CSX) as a subform of non-cardiac chest pain (NCCP). METHODS: We investigated 114 patients with CSX using symptom questionnaires. A subgroup of these patients were investigated regarding upper gastrointestinal disorders (GIs) and treated with PPI. Patients not willing to participate in investigation and treatment served as control group. RESULTS: Thirty-six patients denied any residual symptoms and were not further evaluated. After informed consent in 27 of the remaining 78 patients, we determined the prevalence of disorders of the upper GI tract and quantifi ed the effect of treatment with pantoprazole. We found a high prevalence of gastroenterological pathologies (26/27 patients, 97%)with gastritis, gastroesophageal reflux disease (GERD) and acid reflux as the most common associated disorders. If treated according to the study protocol, these patients showed a significant improvement in the symptom score. Patients treated by primary care physicians, not according to the study protocol had a minor response to treatment (n = 19, -43%), while patients not treated at all (n = 26) had no improvement of symptoms (-0%). CONCLUSION: Disorders of the upper GI tract are a frequent origin of CSX in a German population and can be treated with pantoprazole if given for a longer period.
基金supported by the National Science Foundation of China(No.41374129)Science and Technology Project of Shanxi Province(No.20100321066)Research and Development Project of National Major Scientifi c Research Equipment(No.ZDYZ2012-1-05-04)
文摘With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic (TEM) method is favorable for prospecting conductive layers because of the coupling relationship between its field structure and formation. However, the shielding effect of conductive overburden would not only require a longer observation time when prospecting the same depth but also weaken the anomalous response of underlying layers. Through direct time domain numerical simulation and horizontal layered earth forward modeling, this paper estimates the length of observation time required to prospect the target, and the distinguishable criterion of multilayer water-filled goal is presented with observation error according to the effect of noise on observation data. The observed emf curves from Dazigou Coal Mine, Shanxi Province can distinguish multilayer water-filled goaf. In quantitative inversion interpretation of observed curves, using electric logging data as initial parameters restrains the equivalence caused by coal formation thin layers. The deduced three-layer and two-layer water-filled goals are confirmed by the drilling hole. The result suggests that when observation time is long enough and with the anomalous situation of underlying layers being greater than the observation error, the use of the central loop TEM method to orosoect a multilaver water-filled goaf is feasible.
文摘Objective To study prognostic characteristics of cardiac troponin I (cTnI) elevation in acute ischemic stroke. Methods We retrospectively studied patients (n = 248) with acute ischemic stroke, acute ST-segment elevation myocardial infarction, and acute non-ST-elevation myocardial infarction who were treated between January 2013 and October 2015. Baseline demographic data and changes in cTnI levels among these three groups were compared. Patients with acute ischemic stroke were assigned to either the cTnI elevation group (cTnI 〉 0.034 ng/mL) or the no cTnI elevation group (cTnI ≤ 0.034 ng/mL). Logistic regression analysis was used to identify risk factors associated with elevated serum cTnI in patients with acute ischemic stroke. Moreover, the duration of hospital stay and incidence of major cardiovascular outcomes were compared in patients with acute ischemic stroke, with or without elevated cTnI. Results In this study population of patients with acute ischemic stroke (n = 178), acute ST-segment elevation myocardial infarction (n = 35), and acute non-ST-elevation myocardial infarction (n = 35), patients with acute ischemic stroke with elevated cTnI comprised 18.54% of subjects. Patients with elevated cTnI were older and more likely to have a history of hypertension. In addition, these patients had higher levels of inflammatory markers, reduced renal functions, increased D-dimer levels, higher NIH stroke scores, and lower left ventricular ejection fractions. Logistic regression analysis showed that both percentage of neutrophil and NIH stroke scores were elevated; estimated glomerular filtration rate and left ventricular ejection fraction were decreased in patients with acute ischemic stroke who had elevated cTnI, and they had more frequent major cardiovascular events during hospital stay. Conclusion Elevated cTnI detected in patients with acute ischemic stroke, indicated a greater likelihood of poor short-term prognosis during hospital stay.
文摘Atherosclerosis and its related cardiovascular disease is the most common cause of morbidity and mortality in the Western world. The roots of this disease may lie, in part, in dietary and lifestyle behaviors, indicating that modifica- tion of these behaviors may lead to profound improvements.
基金supported by Munzur University Scientific Investigations Project Unit(PPMUB018-13)。
文摘The leaching behavior of Tunceli malachite mineral was investigated in nitric acid solutions by two steps to evaluate the effect of various experimental parameters.In the first step,the optimal conditions for the leaching process were determined,while in the second step,a kinetic evaluation for the process was performed.In the optimization experiments,the concentration of nitric acid,temperature,stirring speed,and solid-to-liquid ratio were selected as the independent variables,and the central composite design method(CCD)was applied to the experimental data.At the end of the experiments,the optimal values for the concentration of nitric acid,temperature,solid-to-liquid ratio and stirring speed were determined to be 0.5 mol/L,50℃,0.004 g/m L and 500 r/min,respectively.Under the optimal conditions,the leaching rate was found to be 99%for 120 min of reaction time.In the kinetic evaluation tests,the effects of the concentration of nitric acid,temperature,stirring speed,solid-to-liquid ratio and particle size on the leaching rate of copper from malachite were investigated.In these tests,it was determined that the leaching rate increased with the increase in the temperature,acid concentration and stirring speed,and with the decrease in the particle size and solid-to-liquid ratio.In consequence of the kinetic analysis,it was observed that the leaching kinetics followed the mixed kinetic model,and a mathematical model for the leaching process was introduced.The activation energy for this process was calculated to be 36.23 k J/mol.
文摘The noise level of coal face by full-mechanized coal winning technology was measured in a coal mine. And then it was analyzed and evaluated using environment science, ergonomics and fussy mathematics analysis. Basis of the statistics and analysis of the measured noise level some measures, such as applying the new materials and improving the construction of the equipment, were carried out. The resuts show that they can reduce the noise level, improve the working environment and enhance the work efficiency.
基金Under the auspices of National Natural Science Foundation of China(No.41201162)
文摘Using the radius of gyration from fractal theory, this paper describes the calculation of fractal dimensions for the four tiers of central places in the Jilin Central Urban Agglomeration(JCUA), Jilin Province, China and the structural characteristics of each tier: 1) the 1st tier central place, Changchun Proper(not including Shuangyang District), provides the most service functions and has the most stable primate position; 2) the 2nd tier central places, Jilin Proper, Siping Proper, Liaoyuan Proper and Songyuan Proper have unclear statuses and do not provide certain functions; 3) the 3rd tier central places comprise 23 county-level cities, counties and urban districts(including Shuangyang District of Changchun), exhibiting a dense spatial structure that agrees with theory; 4) the 4th tier contains the largest number of central places(248 designated towns), but they are loosely distributed. In this study, a spatial image of the JCUA was created, based on vectorized data of the urban settlement distribution, which was then modified and abstracted to create a hexagonal network covering the JCUA. Compared to the traditional central place model, the modified spatial image conforms to the K = 3 principle. In reality, however, the growth of some 3rd tier central places should be increased with the cities being upgraded to the 2nd tier so as to overcome that tier′s functional deficiency. The loose distribution in the 4th tier should also be changed. This apparent anomaly can be explained by the fact that the classic hexagon model used to describe the way market areas layout does not exist in the real world. However, this should not be viewed as an obstacle to using central place theory. If its assumptions are properly applied, it can still assist research into the spatial structure of regions.
基金This study was supported by the National Natural Science Foundation of China (81470491). We thank all the staff of the Department of Cardiology in Xuanwu Hospital affilitated to the Capital Medical University for their contribution to this study.
文摘Objective To investigate whether coronary artery revascularization therapies (CART), including percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), can improve the in-hospital and long-term outcomes for acute myocardial infarction (AMI) patients with prior ischemic stroke (IS). Methods A total of 387 AMI patients with prior IS were enrolled consecutively from January 15, 2005 to December 24, 2011 in this cohort study. All patients were categorized into the CART group (n = 204) or the conservative medications (CM) group (n = 183). In-hospital cardiocerebral events and long-term mortality of the two groups after an average follow-up of 36 months were recorded by Kaplan-Meier survival curves and compared by Logistic regression and the Cox regression model. Results The CART patients were younger (66.5 ± 9.7 years vs. 71.7 ± 9.7 years, P 〈 0.01), had less non-ST segment elevation myocardial infarction (11.8% vs. 20.8%, P = 0.016) and more multiple-vascular coronary lesions (50% vs. 69.4%, P = 0.031). The hospitalization incidence of cardiocerebral events in the CART group was 9.3% while 26.2% in the CM group (P 〈 0.01). CART significantly reduced the risk of in-hospital cardiocerebral events by 65% [adjusted odds ratio (OR) = 0.35, 95% CI: 0.13-0.92]. By the end of follow-up, 57 cases (41.6%) died in CM group (n = 137) and 24 cases (12.2%) died in CART group (n = 197). Cox regression indicated that CART decreased the long-term mortality by 72% [adjusted hazard ratio (HR) = 0.28, 95% CI: 0.064).46], while categorical analysis indicated no s{gnificant dif- ference between PCI and CABG. Conclusions CART has a significant effect on improving the in-hospital and long-term prognoses for AMI patients with prior IS.
文摘The study investigates the nonlinear heart rate variability indices in different seasons and their dependence on current meteorological factors. The study included 61 relatively healthy student volunteers, their age were 19-23 and they were examined repeatedly in different seasons. The HRV (heart rate variability) recording was performed with the use of the hardware-software complex "Varikard 2.51" Nonlinear HRV indices were calculated by means of the Kubios HRV 2.1. The following indicators: SD1, SD2, SD1/SD2, D2, DFA, SampEn and quantitative indicators of recurrence analysis (RQA )---Lmean, Lmax, REC, DET, ShanEn had been analyzed. Statistical analysis was performed using the Statistica 6.0. For the detection of between-group differences were used Repeated Measures ANOVA, and the dependence of nonlinear HRV indices on meteorological was analyzed with the use of multiple non-linear regression. The investigation showed a relative increase in SampEn and the reduction of al in winter and spring seasons, strengthening relationships SampEn correlation with other indicators in the winter season as well as the dependence SampEn on meteorological factors in summer. The detected changes can be considered as the realization of adaptive response of a healthy body.
文摘Background The neutrophil-to-lymphocyte (N/L) ratio has been associated with poor prognosis in patients with heart failure, but it has not been compared with N-terminal pro-brain natriuretic peptide (NT-proBNP) in elderly patients with chronic heart failure (CHF). We sought to make this comparison. Methods A total of 1355 elderly patients with CHF were analyzed. A multivariate logistic regression model was used to analyze the variables associated with atrial fibrillation (AF). Cox regression analysis was used to assess the multivariable rela- tionship between the N/L ratio, NT-proBNP level, and subsequent major cardiovascular events (MCE). Results In the multiple logistic regression analysis, the N/L ratio was demonstrated as a risk factor for AF in elderly patients with CHF [odds ratio (OR): 1.079, 95% confi- dence interval (CI): 1.027-1.134, P = 0.003]. The median follow-up period was 18 months. In a multivariable model using tertiles of both variables, the highest tertile of the N/L ratio was significantly associated with MCE [hazard ratio (HR): 1.407, 95% CI: 1.098-1.802, P = 0.007] compared with the lowest tertile. Similarly, the highest NT-proBNP tertile was also significantly associated with MCE (HR: 1.461, 95% CI: 1.104-1.934, P- 0.008). Conclusions In elderly patients with CHF, the N/L ratio is one of the important risk factors for AF and it is an inexpensive and readily available marker with similar independent prognostic power to NT-proBNP. The risk of MCE increases 1.407-fold when the N/L ratio is elevated to the highest tertile.
基金supported by the National Basic Research Program of China(973 project,grant number:2014CB542902)Tianjin Hongrentang Pharmaceutical Co.,Ltd.,Tianjin,China(grant number:HX202016)。
文摘Objective: This study aimed to explore the effects of Chinese patent medicine(CPM) in reducing the incidence of major adverse cardiovascular events(MACE) in patients with coronary heart disease(CHD) angina pectoris and improving clinical effectiveness and provide evidence for its use as clinical adjuvant therapy.Methods: Twenty-eight thousand five hundred and seventeen patients hospitalized with CHD angina pectoris from 6 hospitals were divided into CPM group(n = 11,374) and non-CPM group(n = 17,143) to evaluate the incidence of MACE, including myocardial infarction, percutaneous coronary intervention, and coronary artery bypass grafting.Results: The incidence of MACE in the CPM group was lower than that in the non-CPM group. CPM therapy was an independent protective factor that reduced the overall risk of MACE [adjusted hazard ratio = 0.40, 95% confidence interval(0.33;0.49)]. Patients in the CPM group who received one, two, or three types of CPM could benefit from adjuvant treatment with CPM, and taking more types of CPM was associated with a lower risk of MACE. In addition, the male population was better than the female population at taking CPM, and middle-aged people aged 55 to 64 were more suited to take CPM based on Western medicine.Conclusions: The use of CPM as adjuvant therapy can decrease the occurrence of MACE in patients with CHD angina pectoris,especially in men and middle-aged people, and the drug treatment plan should be optimized accordingly. However, this conclusion needs further verification by prospective cohort studies in the future.
基金National Natural Science Foundation of China(No.51375338)National Key R&D Program of China(No.2017YFF0108102)
文摘A cylindrical coordinate measuring machine for the detection of large-size rotational parts is introduced. The measuring machine can simultaneously measure the geometrical dimensions, form and position errors of the inner and outer surfaces. Since the maximum length of the workpiece can reach 2 000 mm , it is difficult to be clamped and adjusted and easy to produce clamping error. The eccentricity can be up to 1.5 mm, which has an interaction effect with the probe mounting offset. We mainly study the probe offset of the measuring machine and the influence of the workpiece clamping error on the measurement. A method of controlling the offset of the measuring probe is proposed. The effect of the clamping error is eliminated through the space coordinate transformation of the workpiece axis, and the axis is fitted by the least square method. Finally, a common fixture can be realized to meet the clamping requirements of the workpiece.