The mechanical properties of residual coal pillars under the influence of upward mining disturbances significantly affect the safety of residual mining activities on working faces.This study conducted low-frequency di...The mechanical properties of residual coal pillars under the influence of upward mining disturbances significantly affect the safety of residual mining activities on working faces.This study conducted low-frequency disturbance dynamic uniaxial compression tests on coal specimens using a self-developed dynamic-static load coupling electro-hydraulic servo system,and studied the strength evolutions,surface deformations,acoustic emission(AE)characteristic parameters,and the failure modes of coal specimens with different static preloading levels were studied.The disturbance damage is positively correlated with the coal specimen static preload level.Specifically,the cumulative AE count rates of the initial accelerated damage stage for the coal specimens with static preloading level of 60%and 70%of the uniaxial compressive strength(UCS)were 2.66 and 3.19 times that of the 50%UCS specimens,respectively.Macroscopically,this behaviour manifested as a decrease in the compressive strength,and the mean strengths of the disturbance-damaged coal specimens with 60%and 70%of UCS static preloading decreased by 8.53%and 9.32%,respectively,compared to those of the specimens under pure static loading.The crack sources,such as the primary fissures,strongly control the dynamic response of the coal specimen.The difference between the dynamic responses of the coal specimens and that of dense rocks is significant.展开更多
Background Increased levels of inflammatory markers have been documented in various settings of coronary artery disease. The vulnerability of coronary lesions in acute myocardial infarction(AMI) at the time of onset m...Background Increased levels of inflammatory markers have been documented in various settings of coronary artery disease. The vulnerability of coronary lesions in acute myocardial infarction(AMI) at the time of onset may be related to serum levels of C reactive protein(CRP) on admission, before CRP levels are affected by myocardial damage.Objective This study assessed the predictive value of CRP levels within six hours after the onset of acute anterior myocardial infarction with primary percutaneous coronary intervention(PCI).Methods The plasma CRP of 76 patients with first acute anterior myocardial infarction was measured within 6 hours after onset. They were divided into 2 groups: group 1( n =20) with elevated CRP( ≥0.3mg/dl ) on admission within 6 hours after onset and group 2( n =56) with normal CRP( <0.3mg/dl ) within 6 hours after onset. All patients were treated by primary PCI. The primary combined end points, including death due to cardiac causes, re MI related to the infarction artery(RIA) and repeat intervention of the RIA, and the restenosis rate were assessed in relation to CRP levels within 6 hours after onset. Left ventricular end diastolic volume index(EDVI),end systolic volume index(ESVI),and ejection fraction(EF) on admission and 6 month after the onset were assessed by left ventriculography. Changes in EDVI(ΔEDVI),ESVI(ΔESVI), and EF(ΔEF) were obtained by subtracting respective on admission values from corresponding 6 month follow up values. Results There were no significant differences in baseline characteristics between the two groups. The primary combined end points were significantly more frequent in group 1(20%) than those in group 2( 1.79% , P <0.01 ).In addition, restenosis rates were significantly higher in group 1 than in group 2(41.18% vs 16.07%, P<0.05). Group 1 showed greater increases in left ventricular volume and less improvement in EF compared with group 2(ΔEDVI 6.31 ±2.17 vs 3.29 ±9.46ml/m 2 , ΔESVI 5.92 ±2.31 vs 3.86 ±1.08ml/m 2 , ΔEF 1.92 ±0.47 vs 4.79 ±1.73% , P <0.05 , respectively).Conclusions CRP levels within 6 hours after the onset of AMI might predict adverse outcome after primary PCI and progressive ventricular remodeling within 6 month of AMI.展开更多
Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was gen...Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was generated that can be monitored using microseismic(MS)monitoring techniques.Two MS monitoring systems were established in two typical underground powerhouse caverns featuring distinct geostress levels.The MS b-values associated with rock mass large deformation and their temporal variation are analysed.The results showed that the MS bvalue in course of rock mass deformation was less than 1.0 in the underground powerhouse caverns at a high stress level while larger than 1.5 at a low stress level.Prior to the rock mass deformation,the MS b-values derived from both the high-stress and low-stress underground powerhouse caverns show an incremental decrease over 10%within 10 d.The results contribute to understanding the fracturing characteristics of MS sources associated with rock mass large deformation and provide a reference for early warning of rock mass large deformation in underground powerhouse caverns.展开更多
The objective of this study is to determine the effect of different protein levels on the growth performance and metabolic rate of nutrition in broilers. Total 360 healthy and weight closed local broilers of 3 weeks w...The objective of this study is to determine the effect of different protein levels on the growth performance and metabolic rate of nutrition in broilers. Total 360 healthy and weight closed local broilers of 3 weeks were chosen and then divided into three groups randomly by one factor. Each group contains three handlings, each handling consists of 40 broilers. The period of experiment was 7 weeks. The metabolic experiment was performed at the 7th week. Three different protein levels were used in broilers＇ diet. The levels of protein were 19%, 17.5% and 16%. The results showed that the different levels of protein in crude dietary had significant difference between 19% group and the other two groups. The average daily weight gain and daily efficiency were significantly higher than that of the other two groups （P〈0.05）. Compared to protein levels of 19% and 16%, there was no significant difference in the metabolism of calcium （P〉0.05）, and the metabolic rate of the impact of phosphorus was significantly different （P〈0.05）. The result showed that when protein level was 19%, the growth of the local broiler was the best.展开更多
It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage ...It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage and declined to its lowest level at the latter stage of root rapid growth, and then increased slightly. GSA in leaf blades had positive correlation with nitrogen level during the whole period of growth. GSA in roots showed the same tendency as it in leaf blades at the early middle stage of growth, but at the latter stage of growth, no positive correlation was established. GSA in leaf blades was the strongest compared with crowns, petioles and roots, and could represent the highest enzyme activity of the whole plant. GSA had quadratic curvilinear correlation with root yield and sugar production. GSA in leaf blades had significant positive correlation with α-NH2-N at the foliage rapid growth stage.展开更多
A 45-day experiment was carried out to evaluate the growth performance, digestive enzymes activity and biochemical response of Cirrhinus mrigala fed graded levels of oil. Three isonitrogenous purified diets （6%, 8% ...A 45-day experiment was carried out to evaluate the growth performance, digestive enzymes activity and biochemical response of Cirrhinus mrigala fed graded levels of oil. Three isonitrogenous purified diets （6%, 8% and 10% of oil） were formulated. A total of 108 juveniles of Cirrhinus mrigala （5.95±0.25） g were equally distributed in triplicate groups in nine plastic tanks of 100 L capacity and fed under natural light cycle. Growth performance of the fish significantly reflected the effect of inclusion levels of oil tested but the diet with 8% lipid had the best significant growth performance [% weight gain, Feed Conversion Ratio （FCR） and Specific Growth Rate （SGR）], across different experimental groups. Levels of secretion of digestive enzymes in the fish fed different experimental diets resulted in significant values of （p〈0.05） amylase and lipase, while Aspartate transaminase （AST）, Alanine transaminase （ALT）, Lactate dehydrogenase （LDH） and Malate dehydrognnase （MDH） values in the muscle and liver decreased significantly （F〈0.05） as the levels of oii in the diet increased. However, serum biochemical parameters did not record any significant difference 6o〉0.05） with the exception of the total lipid across diets. The study confirmed the inclusion effect of graded levels ofoil in juvenile Mrigal diet, but the inclusion should not be more than 8% to avert growth depression.展开更多
In order to research effects of the nitrogen top-dressing levels on carbon-nitrogen metabolism and yield of Desmodium styracifolium, a field experiment was conducted on the research farm of Guangxi University in 2007....In order to research effects of the nitrogen top-dressing levels on carbon-nitrogen metabolism and yield of Desmodium styracifolium, a field experiment was conducted on the research farm of Guangxi University in 2007. Some physiological indexes and yield ofD. styracifolium were compared among five nitrogen top-dressing levels （0, 37.5, 75.0, 112.5 and 150.0 kg N. hm-2）. Results showed that the nitrogen top-dressing could significantly increase the contents of chlorophyll, soluble protein, sucrose and nitrogen as well as nitrate reducase activity. However, there were no significant differences in most of these indexes under high nitrogen levels. Consistently, there was no significant difference in yield among nitrogen top-dressing levels of 75 kg N.hm-2, 112.5 kg N. hm-2 and 150 kg N-hm-2. Therefore, the optimum nitrogen top-dressing level ofD. styracifolium was 75 kg N. hm-2.展开更多
The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rap...The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rapidly to reach its peak from seedling stage to foliage rapid growth stage, and then declined gradually. GOGATA was enhanced with increasing nitrogen levels and had significant positive correlation with nitrogen levels at the middle stage of growth GOGATA in leaf blades was the strongest compared with crowns, petioles and roots, thus, it could represent the highest enzyme activity of the whole plant. GOGATA had quadratic curvilinear correlation with root yield and sugar production. GOGATA in leaf blades had significant positive correlation with α-NH 2-N at the foliage rapid growth stage while GOGATA in roots existed this relation at the latter stage of growth. GOGATA in roots had significant negative correlation with sugar content at harvest.展开更多
Background Potassium(K)is an essential nutrient for plant growth and development.However,plant fertilization ignoring the soil K level is very likely to cause excessive fertilizer use,and further arouse a series of si...Background Potassium(K)is an essential nutrient for plant growth and development.However,plant fertilization ignoring the soil K level is very likely to cause excessive fertilizer use,and further arouse a series of side effects.This study investigated the response of cotton growth to different soil K levels and the uptake of major nutrients,aiming to evaluate the appropriate K supply level for cotton growth.Using a random block design with 6 soil K levels,we conducted 18 micro-zones field experiments over two continuous years.The soil available K concentration of each treatment was K1(99.77-100.90 mg·kg^(-1)),K2(110.90-111.26 mg·kg^(-1)),K3(123.48-128.88 mg·kg^(-1)),K4(140.13-145.10 mg·kg^(-1)),K5(154.43-155.38 mg·kg^(-1)),and K6(165.77-168.75 mg·kg^(-1)).Cotton nutrient contents,soil nutrient contents,accumulation and distribution of dry matter in cotton were determined,and the relationships between K content in soil and plants and dry matter accumulation were analyzed.Results The soil K content had a significantly positive relationship with dry matter and K accumulation in cotton plants.There were significant differences in dry matter accumulation,single-plant seed cotton yield,mineral nutrient uptake and the proportion of K accumulation in reproductive organs among different soil K levels.The results showed that there was significant difference between K4 and lower K level treatments(K1 and K2),but no significant difference between K4 and higher K level treatments(K5 and K6)in dry matter,single-plant seed cotton yield,or accumulation,distribution and seed cotton production efficiency of N,P and K.Conclusion The soil K level of K4 was able to provide sufficient K for cotton growth in our experiment.Therefore,when the soil K level reached 140.13 mg·kg^(-1),further increasing the soil K concentration no longer had a significant positive effect on cotton growth.展开更多
Highly ionized Spectra from sulfur obtained at an energy of 80 MeV have been studied in the 19.0～53.0 nm wavelength range. Radiative lifetimes for some n =2 level in Be+-like S ⅩⅢwere measured using he beam-foil ti...Highly ionized Spectra from sulfur obtained at an energy of 80 MeV have been studied in the 19.0～53.0 nm wavelength range. Radiative lifetimes for some n =2 level in Be+-like S ⅩⅢwere measured using he beam-foil time of flight method. The results, using an arbitrarily normalized decay curves analysis, are compared with theoretical predictions and earlier measurement.展开更多
基金Projects(51925402,52334005,52304094)supported by the National Natural Science Foundation of ChinaProject(20201102004)supported by the Shanxi Science and Technology Major Project,China。
文摘The mechanical properties of residual coal pillars under the influence of upward mining disturbances significantly affect the safety of residual mining activities on working faces.This study conducted low-frequency disturbance dynamic uniaxial compression tests on coal specimens using a self-developed dynamic-static load coupling electro-hydraulic servo system,and studied the strength evolutions,surface deformations,acoustic emission(AE)characteristic parameters,and the failure modes of coal specimens with different static preloading levels were studied.The disturbance damage is positively correlated with the coal specimen static preload level.Specifically,the cumulative AE count rates of the initial accelerated damage stage for the coal specimens with static preloading level of 60%and 70%of the uniaxial compressive strength(UCS)were 2.66 and 3.19 times that of the 50%UCS specimens,respectively.Macroscopically,this behaviour manifested as a decrease in the compressive strength,and the mean strengths of the disturbance-damaged coal specimens with 60%and 70%of UCS static preloading decreased by 8.53%and 9.32%,respectively,compared to those of the specimens under pure static loading.The crack sources,such as the primary fissures,strongly control the dynamic response of the coal specimen.The difference between the dynamic responses of the coal specimens and that of dense rocks is significant.
文摘Background Increased levels of inflammatory markers have been documented in various settings of coronary artery disease. The vulnerability of coronary lesions in acute myocardial infarction(AMI) at the time of onset may be related to serum levels of C reactive protein(CRP) on admission, before CRP levels are affected by myocardial damage.Objective This study assessed the predictive value of CRP levels within six hours after the onset of acute anterior myocardial infarction with primary percutaneous coronary intervention(PCI).Methods The plasma CRP of 76 patients with first acute anterior myocardial infarction was measured within 6 hours after onset. They were divided into 2 groups: group 1( n =20) with elevated CRP( ≥0.3mg/dl ) on admission within 6 hours after onset and group 2( n =56) with normal CRP( <0.3mg/dl ) within 6 hours after onset. All patients were treated by primary PCI. The primary combined end points, including death due to cardiac causes, re MI related to the infarction artery(RIA) and repeat intervention of the RIA, and the restenosis rate were assessed in relation to CRP levels within 6 hours after onset. Left ventricular end diastolic volume index(EDVI),end systolic volume index(ESVI),and ejection fraction(EF) on admission and 6 month after the onset were assessed by left ventriculography. Changes in EDVI(ΔEDVI),ESVI(ΔESVI), and EF(ΔEF) were obtained by subtracting respective on admission values from corresponding 6 month follow up values. Results There were no significant differences in baseline characteristics between the two groups. The primary combined end points were significantly more frequent in group 1(20%) than those in group 2( 1.79% , P <0.01 ).In addition, restenosis rates were significantly higher in group 1 than in group 2(41.18% vs 16.07%, P<0.05). Group 1 showed greater increases in left ventricular volume and less improvement in EF compared with group 2(ΔEDVI 6.31 ±2.17 vs 3.29 ±9.46ml/m 2 , ΔESVI 5.92 ±2.31 vs 3.86 ±1.08ml/m 2 , ΔEF 1.92 ±0.47 vs 4.79 ±1.73% , P <0.05 , respectively).Conclusions CRP levels within 6 hours after the onset of AMI might predict adverse outcome after primary PCI and progressive ventricular remodeling within 6 month of AMI.
基金Projects(51809221,51679158)supported by the National Natural Science Foundation of ChinaProject(KFJJ20-06M)supported by the State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology),China。
文摘Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was generated that can be monitored using microseismic(MS)monitoring techniques.Two MS monitoring systems were established in two typical underground powerhouse caverns featuring distinct geostress levels.The MS b-values associated with rock mass large deformation and their temporal variation are analysed.The results showed that the MS bvalue in course of rock mass deformation was less than 1.0 in the underground powerhouse caverns at a high stress level while larger than 1.5 at a low stress level.Prior to the rock mass deformation,the MS b-values derived from both the high-stress and low-stress underground powerhouse caverns show an incremental decrease over 10%within 10 d.The results contribute to understanding the fracturing characteristics of MS sources associated with rock mass large deformation and provide a reference for early warning of rock mass large deformation in underground powerhouse caverns.
基金Supported by Youth Funded Projects of Heilongjiang Academy of Agricultural Sciences (2007AA6CN033)
文摘The objective of this study is to determine the effect of different protein levels on the growth performance and metabolic rate of nutrition in broilers. Total 360 healthy and weight closed local broilers of 3 weeks were chosen and then divided into three groups randomly by one factor. Each group contains three handlings, each handling consists of 40 broilers. The period of experiment was 7 weeks. The metabolic experiment was performed at the 7th week. Three different protein levels were used in broilers＇ diet. The levels of protein were 19%, 17.5% and 16%. The results showed that the different levels of protein in crude dietary had significant difference between 19% group and the other two groups. The average daily weight gain and daily efficiency were significantly higher than that of the other two groups （P〈0.05）. Compared to protein levels of 19% and 16%, there was no significant difference in the metabolism of calcium （P〉0.05）, and the metabolic rate of the impact of phosphorus was significantly different （P〈0.05）. The result showed that when protein level was 19%, the growth of the local broiler was the best.
文摘It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage and declined to its lowest level at the latter stage of root rapid growth, and then increased slightly. GSA in leaf blades had positive correlation with nitrogen level during the whole period of growth. GSA in roots showed the same tendency as it in leaf blades at the early middle stage of growth, but at the latter stage of growth, no positive correlation was established. GSA in leaf blades was the strongest compared with crowns, petioles and roots, and could represent the highest enzyme activity of the whole plant. GSA had quadratic curvilinear correlation with root yield and sugar production. GSA in leaf blades had significant positive correlation with α-NH2-N at the foliage rapid growth stage.
文摘A 45-day experiment was carried out to evaluate the growth performance, digestive enzymes activity and biochemical response of Cirrhinus mrigala fed graded levels of oil. Three isonitrogenous purified diets （6%, 8% and 10% of oil） were formulated. A total of 108 juveniles of Cirrhinus mrigala （5.95±0.25） g were equally distributed in triplicate groups in nine plastic tanks of 100 L capacity and fed under natural light cycle. Growth performance of the fish significantly reflected the effect of inclusion levels of oil tested but the diet with 8% lipid had the best significant growth performance [% weight gain, Feed Conversion Ratio （FCR） and Specific Growth Rate （SGR）], across different experimental groups. Levels of secretion of digestive enzymes in the fish fed different experimental diets resulted in significant values of （p〈0.05） amylase and lipase, while Aspartate transaminase （AST）, Alanine transaminase （ALT）, Lactate dehydrogenase （LDH） and Malate dehydrognnase （MDH） values in the muscle and liver decreased significantly （F〈0.05） as the levels of oii in the diet increased. However, serum biochemical parameters did not record any significant difference 6o〉0.05） with the exception of the total lipid across diets. The study confirmed the inclusion effect of graded levels ofoil in juvenile Mrigal diet, but the inclusion should not be more than 8% to avert growth depression.
基金Supported by Scientifi c Research Foundation of Guangxi University (x061106)
文摘In order to research effects of the nitrogen top-dressing levels on carbon-nitrogen metabolism and yield of Desmodium styracifolium, a field experiment was conducted on the research farm of Guangxi University in 2007. Some physiological indexes and yield ofD. styracifolium were compared among five nitrogen top-dressing levels （0, 37.5, 75.0, 112.5 and 150.0 kg N. hm-2）. Results showed that the nitrogen top-dressing could significantly increase the contents of chlorophyll, soluble protein, sucrose and nitrogen as well as nitrate reducase activity. However, there were no significant differences in most of these indexes under high nitrogen levels. Consistently, there was no significant difference in yield among nitrogen top-dressing levels of 75 kg N.hm-2, 112.5 kg N. hm-2 and 150 kg N-hm-2. Therefore, the optimum nitrogen top-dressing level ofD. styracifolium was 75 kg N. hm-2.
文摘The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rapidly to reach its peak from seedling stage to foliage rapid growth stage, and then declined gradually. GOGATA was enhanced with increasing nitrogen levels and had significant positive correlation with nitrogen levels at the middle stage of growth GOGATA in leaf blades was the strongest compared with crowns, petioles and roots, thus, it could represent the highest enzyme activity of the whole plant. GOGATA had quadratic curvilinear correlation with root yield and sugar production. GOGATA in leaf blades had significant positive correlation with α-NH 2-N at the foliage rapid growth stage while GOGATA in roots existed this relation at the latter stage of growth. GOGATA in roots had significant negative correlation with sugar content at harvest.
基金supported by Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciencesthe earmarked fund of China Agricultural Research System of China(CARS-15-11).
文摘Background Potassium(K)is an essential nutrient for plant growth and development.However,plant fertilization ignoring the soil K level is very likely to cause excessive fertilizer use,and further arouse a series of side effects.This study investigated the response of cotton growth to different soil K levels and the uptake of major nutrients,aiming to evaluate the appropriate K supply level for cotton growth.Using a random block design with 6 soil K levels,we conducted 18 micro-zones field experiments over two continuous years.The soil available K concentration of each treatment was K1(99.77-100.90 mg·kg^(-1)),K2(110.90-111.26 mg·kg^(-1)),K3(123.48-128.88 mg·kg^(-1)),K4(140.13-145.10 mg·kg^(-1)),K5(154.43-155.38 mg·kg^(-1)),and K6(165.77-168.75 mg·kg^(-1)).Cotton nutrient contents,soil nutrient contents,accumulation and distribution of dry matter in cotton were determined,and the relationships between K content in soil and plants and dry matter accumulation were analyzed.Results The soil K content had a significantly positive relationship with dry matter and K accumulation in cotton plants.There were significant differences in dry matter accumulation,single-plant seed cotton yield,mineral nutrient uptake and the proportion of K accumulation in reproductive organs among different soil K levels.The results showed that there was significant difference between K4 and lower K level treatments(K1 and K2),but no significant difference between K4 and higher K level treatments(K5 and K6)in dry matter,single-plant seed cotton yield,or accumulation,distribution and seed cotton production efficiency of N,P and K.Conclusion The soil K level of K4 was able to provide sufficient K for cotton growth in our experiment.Therefore,when the soil K level reached 140.13 mg·kg^(-1),further increasing the soil K concentration no longer had a significant positive effect on cotton growth.
文摘Highly ionized Spectra from sulfur obtained at an energy of 80 MeV have been studied in the 19.0～53.0 nm wavelength range. Radiative lifetimes for some n =2 level in Be+-like S ⅩⅢwere measured using he beam-foil time of flight method. The results, using an arbitrarily normalized decay curves analysis, are compared with theoretical predictions and earlier measurement.
