Surface defects,including dents,spalls,and cracks,for rolling element bearings are the most common faults in rotating machinery.The accurate model for the time-varying excitation is the basis for the vibration mechani...Surface defects,including dents,spalls,and cracks,for rolling element bearings are the most common faults in rotating machinery.The accurate model for the time-varying excitation is the basis for the vibration mechanism analysis and fault feature extraction.However,in conventional investigations,this issue is not well and fully addressed from the perspective of theoretical analysis and physical derivation.In this study,an improved analytical model for time-varying displacement excitations(TVDEs)caused by surface defects is theoretically formulated.First and foremost,the physical mechanism for the effect of defect sizes on the physical process of rolling element-defect interaction is revealed.According to the physical interaction mechanism between the rolling element and different types of defects,the relationship between time-varying displacement pulse and defect sizes is further analytically derived.With the obtained time-varying displacement pulse,the dynamic model for the deep groove bearings considering the internal excitation caused by the surface defect is established.The nonlinear vibration responses and fault features induced by surface defects are analyzed using the proposed TVDE model.The results suggest that the presence of surface defects may result in the occurrence of the dual-impulse phenomenon,which can serve as indexes for surface-defect fault diagnosis.展开更多
With high nutrition and health value,blueberry receives much concern in recent years. Blueberry experts in the world are cultivating new blueberry varieties. They have come up with constructive theoretical support and...With high nutrition and health value,blueberry receives much concern in recent years. Blueberry experts in the world are cultivating new blueberry varieties. They have come up with constructive theoretical support and planting technology researches and are constantly devoted to expanding blueberry planting latitudes. This paper elaborated researches of blueberry at home and abroad,current development situation of blueberry in China and Guangdong Province,analyzed strengths of planting blueberry in Guangdong. Besides,it came up with recommendations for development of blueberry industry. Finally,it discussed development prospects of blueberry planting in Guangdong.展开更多
In this study,waste cotton fabric was used as cellulose raw material and pretreated in aqueous NaOH/urea solution system to investigate the effect of NaOH/urea pretreatment solution on the hydrolysis of cotton fiber.T...In this study,waste cotton fabric was used as cellulose raw material and pretreated in aqueous NaOH/urea solution system to investigate the effect of NaOH/urea pretreatment solution on the hydrolysis of cotton fiber.The cotton fiber was pretreated with different conditions of aqueous NaOH/urea solution,and the pretreated cotton fiber was hydrolyzed under the same conditions as the original cotton fiber.The results of characterization analysis showed that water retention value of pretreated cotton fiber was higher than that of unpretreated sample.Moreover,the cotton fiber presented both a convoluted structure and a coarser surface,XRD results suggested that the crystallinity degree of cellulose decreased dramatically,more cellulose II appeared,and the hydrogen bond is broken.Among the different pretreatment conditions,the pretreatment effect was the best when the reaction temperature was 0°C,the solid-liquid ratio was 2:50,and the NaOH/urea ratio was 7:12.The hydrolysis experiments of pretreated and unpretreated cotton fibers showed that when the hydrothermal temperature was 230°C,the heat preservation was 2 h,and the hydrochloric acid concentration was 5 wt.%,the glucose yield reached 29.99%.H+could catalyze the hydrolysis of cotton fiber more effectively due to damage to crystal structure and hydrogen bonds.展开更多
The fretting wear behavior of Zr alloy cladding tube under mixed fretting regime in a high-temperature pressurized water was investigated.The main wear mechanism is adhesive wear,with characters of small-scale delamin...The fretting wear behavior of Zr alloy cladding tube under mixed fretting regime in a high-temperature pressurized water was investigated.The main wear mechanism is adhesive wear,with characters of small-scale delamination at the center of worn area and serious delamination on the worn edge.A long crack throughout the worn area and other cracks propagated towards the substrate are observed.The cross-sectional microstructure of worn area can be divided into a thick third-body layer,thin inner oxide layer and thick tribologically transformed structure layer,and their formation mechanisms are analyzed in detail.Finally,the mixed fretting regime process and the microstructural evolution during fretting wear are discussed.展开更多
The effect of normal force on fretting wear behavior of zirconium alloy tube mated with grid dimple in simulated primary water of pressurized water reactor nuclear power plant was investigated.Results showed that the ...The effect of normal force on fretting wear behavior of zirconium alloy tube mated with grid dimple in simulated primary water of pressurized water reactor nuclear power plant was investigated.Results showed that the maximum wear depth,wear volume and wear coefficient of Zr alloy tube in simulated primary water at 315℃ gradually increased with increasing normal force,while the friction coefficient gradually decreased.Fretting process could be divided into four stages according to the variation of friction coefficient during test.When normal force exceeds 30 N,the fretting regime would transition from gross slip regime to partial slip regime after 3×10^(7 )cycles.Delamination was aggravated with increasing normal force,while abrasive wear became slighter.A thicker third-body layer with monoclinic ZrO_(2) was formed by the tribo-sintering mechanism under higher normal force.In addition,the schematic evolution processes of delamination and third-body layer formation were displayed according to morphology observation.展开更多
The amygdala is an important hub for regulating emotions and is involved in the pathophysiology of many mental diseases,such as depression and anxiety.Meanwhile,the endocannabinoid system plays a crucial role in regul...The amygdala is an important hub for regulating emotions and is involved in the pathophysiology of many mental diseases,such as depression and anxiety.Meanwhile,the endocannabinoid system plays a crucial role in regulating emotions and mainly functions through the cannabinoid type-1 receptor(CB1R),which is strongly expressed in the amygdala of non-human primates(NHPs).However,it remains largely unknown how the CB1Rs in the amygdala of NHPs regulate mental diseases.Here,we investigated the role of CB1R by knocking down the cannabinoid receptor 1(CNR1)gene encoding CB1R in the amygdala of adult marmosets through regional delivery of AAV-SaCas9-gRNA.We found that CB1R knockdown in the amygdala induced anxiety-like behaviors,including disrupted night sleep,agitated psychomotor activity in new environments,and reduced social desire.Moreover,marmosets with CB1R-knockdown had up-regulated plasma cortisol levels.These results indicate that the knockdown of CB1Rs in the amygdala induces anxiety-like behaviors in marmosets,and this may be the mechanism underlying the regulation of anxiety by CB1Rs in the amygdala of NHPs.展开更多
Dear Editor,Sleep is essential for survival in mammals,and there are many examples of how the brain fails to function properly without sleep.These include the importance of sleep for plasticity during development [1],...Dear Editor,Sleep is essential for survival in mammals,and there are many examples of how the brain fails to function properly without sleep.These include the importance of sleep for plasticity during development [1],memory formation and consolidation [2],and the erasure of undesired memories[3] as well as the improvement of memory [4],perceptual skills [5],and learning abilities after sleep [6].展开更多
基金This work is sponsored by the National Natural Science Foundation of China(Nos.52105117&52105118).
文摘Surface defects,including dents,spalls,and cracks,for rolling element bearings are the most common faults in rotating machinery.The accurate model for the time-varying excitation is the basis for the vibration mechanism analysis and fault feature extraction.However,in conventional investigations,this issue is not well and fully addressed from the perspective of theoretical analysis and physical derivation.In this study,an improved analytical model for time-varying displacement excitations(TVDEs)caused by surface defects is theoretically formulated.First and foremost,the physical mechanism for the effect of defect sizes on the physical process of rolling element-defect interaction is revealed.According to the physical interaction mechanism between the rolling element and different types of defects,the relationship between time-varying displacement pulse and defect sizes is further analytically derived.With the obtained time-varying displacement pulse,the dynamic model for the deep groove bearings considering the internal excitation caused by the surface defect is established.The nonlinear vibration responses and fault features induced by surface defects are analyzed using the proposed TVDE model.The results suggest that the presence of surface defects may result in the occurrence of the dual-impulse phenomenon,which can serve as indexes for surface-defect fault diagnosis.
基金Supported by National Science and Technology Project of the Ministry of Science and Technology in the Twelfth Five-Year Plan Period(2012BAD22B0504)Special Project on the Integration of Industry,Education and Research of Guangdong Province(2013B090200065)Science and Technology Planning Project of Guangdong Province(2012B050500009)
文摘With high nutrition and health value,blueberry receives much concern in recent years. Blueberry experts in the world are cultivating new blueberry varieties. They have come up with constructive theoretical support and planting technology researches and are constantly devoted to expanding blueberry planting latitudes. This paper elaborated researches of blueberry at home and abroad,current development situation of blueberry in China and Guangdong Province,analyzed strengths of planting blueberry in Guangdong. Besides,it came up with recommendations for development of blueberry industry. Finally,it discussed development prospects of blueberry planting in Guangdong.
基金supported by the National Natural Science Foundation of China[Nos.51703153 and 21802101].
文摘In this study,waste cotton fabric was used as cellulose raw material and pretreated in aqueous NaOH/urea solution system to investigate the effect of NaOH/urea pretreatment solution on the hydrolysis of cotton fiber.The cotton fiber was pretreated with different conditions of aqueous NaOH/urea solution,and the pretreated cotton fiber was hydrolyzed under the same conditions as the original cotton fiber.The results of characterization analysis showed that water retention value of pretreated cotton fiber was higher than that of unpretreated sample.Moreover,the cotton fiber presented both a convoluted structure and a coarser surface,XRD results suggested that the crystallinity degree of cellulose decreased dramatically,more cellulose II appeared,and the hydrogen bond is broken.Among the different pretreatment conditions,the pretreatment effect was the best when the reaction temperature was 0°C,the solid-liquid ratio was 2:50,and the NaOH/urea ratio was 7:12.The hydrolysis experiments of pretreated and unpretreated cotton fibers showed that when the hydrothermal temperature was 230°C,the heat preservation was 2 h,and the hydrochloric acid concentration was 5 wt.%,the glucose yield reached 29.99%.H+could catalyze the hydrolysis of cotton fiber more effectively due to damage to crystal structure and hydrogen bonds.
基金financially supported by the CNNC Science Fund for Talented Young Scholars,the Youth Innovation Promotion As-sessment CAS(No.2022187)the National Natural Science Founda-tion of China(No.52105221)+1 种基金the IMR Innovation Fund(No.2021-PY10)the open-ended fund of the CAS Key Laboratory of Nu-clear Materials and Safety Assessment(Institute of Metal Research,Chinese Academy of Sciences,China)(No.2020NMSAKF01).
文摘The fretting wear behavior of Zr alloy cladding tube under mixed fretting regime in a high-temperature pressurized water was investigated.The main wear mechanism is adhesive wear,with characters of small-scale delamination at the center of worn area and serious delamination on the worn edge.A long crack throughout the worn area and other cracks propagated towards the substrate are observed.The cross-sectional microstructure of worn area can be divided into a thick third-body layer,thin inner oxide layer and thick tribologically transformed structure layer,and their formation mechanisms are analyzed in detail.Finally,the mixed fretting regime process and the microstructural evolution during fretting wear are discussed.
基金supported by the CNNC Science Fund for Talented Young Scholars,Youth Innovation Promotion Assessment CAS(2022187)the IMR Innovation Fund(No.2021-PY10)the open-ended fund of the CAS Key laboratory of Nuclear Materials and Safety Assessment(Institute of Metal Research,Chinese Academy of Sciences,China)(No.2020NMSAKF01).
文摘The effect of normal force on fretting wear behavior of zirconium alloy tube mated with grid dimple in simulated primary water of pressurized water reactor nuclear power plant was investigated.Results showed that the maximum wear depth,wear volume and wear coefficient of Zr alloy tube in simulated primary water at 315℃ gradually increased with increasing normal force,while the friction coefficient gradually decreased.Fretting process could be divided into four stages according to the variation of friction coefficient during test.When normal force exceeds 30 N,the fretting regime would transition from gross slip regime to partial slip regime after 3×10^(7 )cycles.Delamination was aggravated with increasing normal force,while abrasive wear became slighter.A thicker third-body layer with monoclinic ZrO_(2) was formed by the tribo-sintering mechanism under higher normal force.In addition,the schematic evolution processes of delamination and third-body layer formation were displayed according to morphology observation.
基金supported by the Zhejiang Province Natural Science Foundation of China(LD22H090003)Key-Area Research and Development Program of Guangdong Province(2019B030335001 and 2018B030334001)+3 种基金the National Natural Science Foundation of China(31871070,82090031,32071097,31871056,and 32170991)the Key R&D Program of Zhejiang Province(2020C03009)Fundamental Research Funds for the Central Universities(2021FZZX001-37)the CAMS Innovation Fund for Medical Sciences(2019-I2M-5-057).
文摘The amygdala is an important hub for regulating emotions and is involved in the pathophysiology of many mental diseases,such as depression and anxiety.Meanwhile,the endocannabinoid system plays a crucial role in regulating emotions and mainly functions through the cannabinoid type-1 receptor(CB1R),which is strongly expressed in the amygdala of non-human primates(NHPs).However,it remains largely unknown how the CB1Rs in the amygdala of NHPs regulate mental diseases.Here,we investigated the role of CB1R by knocking down the cannabinoid receptor 1(CNR1)gene encoding CB1R in the amygdala of adult marmosets through regional delivery of AAV-SaCas9-gRNA.We found that CB1R knockdown in the amygdala induced anxiety-like behaviors,including disrupted night sleep,agitated psychomotor activity in new environments,and reduced social desire.Moreover,marmosets with CB1R-knockdown had up-regulated plasma cortisol levels.These results indicate that the knockdown of CB1Rs in the amygdala induces anxiety-like behaviors in marmosets,and this may be the mechanism underlying the regulation of anxiety by CB1Rs in the amygdala of NHPs.
基金supported by the National Natural Science Foundation of China (61703365,31871056, 91732302)Fundamental Research Funds for the Central Universities of China (2018QN81008)+5 种基金the National Key R&D Program of China (2018YFC1005003)Hong Kong Research Grants Council (11102417M and 11101818M)the Innovation and Technology Fund, and the Health and Medical Research Fund(MRP/101/17X and MPF/053/18X)the charitable foundations Wong Chun HongCharlie Lee Charitable FoundationCroucher Foundation。
文摘Dear Editor,Sleep is essential for survival in mammals,and there are many examples of how the brain fails to function properly without sleep.These include the importance of sleep for plasticity during development [1],memory formation and consolidation [2],and the erasure of undesired memories[3] as well as the improvement of memory [4],perceptual skills [5],and learning abilities after sleep [6].
