In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environm...In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environments （enriched, social and isolated conditions）. After 8 weeks, fear conditioning （characterized by percentage of freezing） was observed and analyzed, and rats＇ weight, locomoter activity and foot-shock sensitivity were operated too. The results showed that： （1） Compared with control group, the level of conditioned fear was significantly increased in enriched group, but significantly decreased in isolated group; （2） Enriched and isolated conditions influenced rat＇s weight significantly; （3） Different rearing conditions have no effect on locomoter activity and foot-shock sensitivity. These results indicated that early enriched condition could improve the tone-evoked fear conditioning response, while isolated condition impaired the response.展开更多
The structure and working principle of a two-cylinder four-stroke single-piston hydraulic free piston engine(HFPE) were introduced. The basic vibration equation of free piston assembly(FPA) was established based upon ...The structure and working principle of a two-cylinder four-stroke single-piston hydraulic free piston engine(HFPE) were introduced. The basic vibration equation of free piston assembly(FPA) was established based upon the energy conversion between the injected fuel and the friction together with the load. Both the theoretical and numerical results show that the vibration system of FPA is a nonlinear conservative autonomous system in one cycle. The FPA vibration is symmetric with constant amplitude when FPA is only driven by the compression pressure in the compression accumulator and that in the combustion chamber. When considering the friction and load, FPA could still achieve a stable vibration after a few cycles' adjustment whether the input energy is equal to the consumed energy or not. The vibration characteristics are different when FPA vibrates in the compression stroke and the expansion stroke, which is the unique feature of the single-piston HFPE.展开更多
Objective The resting-state functional magnetic resonance imaging(rs-f MRI)method was used to observe brain activity and its functional connection upon electroacupuncture stimulation at bilateral uterine acupoints(EX-...Objective The resting-state functional magnetic resonance imaging(rs-f MRI)method was used to observe brain activity and its functional connection upon electroacupuncture stimulation at bilateral uterine acupoints(EX-CA1),as well as to investigate the mechanism of acupuncture in the treatment of gynecological diseases.Methods Twenty-two healthy female subjects were stimulated by electroacupuncture at bilateral uterine acupoints;rs-f MRI data of the brain were acquired and standardized.Degree centrality(DC),amplitude of low-frequency fluctuation(ALFF),and regional homogeneity(ReHo)were used to analyze local spontaneous brain activity via acupuncture.An independent component analysis was used to evaluate the functional connectivity of the resting brain networks after acupuncture.Results Analytical results showed that the neural activity intensity of the precuneus lobe,orbitofrontal cortex,lingual gyrus,amygdala,and posterior central gyrus decreased after acupuncture(voxel P<0.001,cluster P<0.05).Functional connectivity analysis revealed weakened auditory and right frontal-parietal networks(voxel P<0.001,cluster P<0.05),enhanced visual network(voxel P<0.001,cluster P<0.05),and synergistic auditory network and hypothalamic-pituitary system.Conclusion Significant differences in neural activity and functional connectivity in specific brain regions were observed after acupuncture intervention at uterine acupoints;the hypothalamic-pituitary system also showed various active states in different brain regions.It is speculated that the effective mechanism of acupuncture at uterine acupoints is related to the regulation of reproductive hormones,emotional changes,and somatic sensations.Therefore,the methods used in this study could clarify the neural mechanism of uterine-point acupuncture in the treatment of gynecological diseases and may serve as a reference for other studies pertaining to acupuncture.展开更多
As a miniaturized direct injection(DI)solution,a self-pressurized injector is of great significance for small aviation piston engines,such as spark-ignited two-stroke heavy-fuel engines.The spray characteristics of DI...As a miniaturized direct injection(DI)solution,a self-pressurized injector is of great significance for small aviation piston engines,such as spark-ignited two-stroke heavy-fuel engines.The spray characteristics of DI injectors are an important application prerequisite.In this paper,the computational fluid dynamics(CFD)software AVL Fire is employed to study the spray characteristics.Two types of spray models are established based on the Han Sheet model and the KH-RT model,and simulation works are carried out according to two types of spray tests in the literature.The comparison results show that in the constant volume bomb test,the spray patterns obtained by simulation under the two sets of environmental pressures are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray contraction of the near nozzle field and the vortex of the far nozzle field better.In the tube test,the spray patterns obtained by simulation under the five sets of flow velocity are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray expansion and the vortex of the far nozzle field better.The RP-3 kerosene spray characteristics of the self-pressurized injector are also experimentally studied,and the results demonstrate that due to the higher viscosity of kerosene,the spray shrinks more easily,resulting in a smaller spray cone angle and larger penetration.Therefore,changes in environmental pressure have greater impact on the kerosene spray pattern.展开更多
The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind...The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind to hydrogen peroxide and produce an activated complex that can react with a wide range of donor molecules. Therefore inactivation of the enzyme may increase the shelf life of raw and un-blanched frozen vegetables. In order to inactivate of the enzyme several physical and chemical treatments among them heating （blanching）, lowering pH or aw or adding chemical additives can be used, however each of the above mentioned methods has a kind of shortcoming. Our results indicated that crude extract of red cabbage and cabbage has the highest and potato and lettuce has the lowest peroxidase activity respectively （P〈0.05）. Although peroxidase resistance to essential oils varied among different vegetables but clove in all concentration had the best effects in decrease ofperoxidase activity （P〈0.05） whereas cumin and fennel were partially able to reduce the enzyme activity. （P〈0.05）.展开更多
We proposed the flat-type permanent magnet linear alternator (LA) for free piston linear alternators (FPLAs) instead of the tubular one. Using the finite element method (FEM), we compare these two kinds of LAs. The FE...We proposed the flat-type permanent magnet linear alternator (LA) for free piston linear alternators (FPLAs) instead of the tubular one. Using the finite element method (FEM), we compare these two kinds of LAs. The FEM result shows that the flat-type permanent magnet LA has higher efficiency and larger output specific power than the tubular one, therefore more suitable for FPLAs, and that the alternator design can be optimized with respect to the permanent magnet length as well as the air gap.展开更多
基金National Natural Science Foundation of China(30770689)Scientific Research Fund of Hunan Provincial Education Department (05B045)National Basic Research Program of China (2002CB410803-04)
文摘In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environments （enriched, social and isolated conditions）. After 8 weeks, fear conditioning （characterized by percentage of freezing） was observed and analyzed, and rats＇ weight, locomoter activity and foot-shock sensitivity were operated too. The results showed that： （1） Compared with control group, the level of conditioned fear was significantly increased in enriched group, but significantly decreased in isolated group; （2） Enriched and isolated conditions influenced rat＇s weight significantly; （3） Different rearing conditions have no effect on locomoter activity and foot-shock sensitivity. These results indicated that early enriched condition could improve the tone-evoked fear conditioning response, while isolated condition impaired the response.
基金Project(51275451)supported by the National Natural Science Foundation of ChinaProject(51221004)supported by the Science Fund for Creative Research Groups of National Natural Science Foundation of China+1 种基金Project(2013CB035400)supported by the National Basic Research Program of ChinaProject(2011BAK03B09)supported by the National Key Technology R&D Program of China
文摘The structure and working principle of a two-cylinder four-stroke single-piston hydraulic free piston engine(HFPE) were introduced. The basic vibration equation of free piston assembly(FPA) was established based upon the energy conversion between the injected fuel and the friction together with the load. Both the theoretical and numerical results show that the vibration system of FPA is a nonlinear conservative autonomous system in one cycle. The FPA vibration is symmetric with constant amplitude when FPA is only driven by the compression pressure in the compression accumulator and that in the combustion chamber. When considering the friction and load, FPA could still achieve a stable vibration after a few cycles' adjustment whether the input energy is equal to the consumed energy or not. The vibration characteristics are different when FPA vibrates in the compression stroke and the expansion stroke, which is the unique feature of the single-piston HFPE.
基金National Nature Science Foundation of China(61872225)Natural Science Foundation of Shandong Province(ZR2020KF013,ZR2020ZD44,ZR2019ZD04,and ZR2020QF043)+1 种基金Introduction and Cultivation Program for Young Creative Talents in Colleges and Universities of Shandong Province(2019-173)Special Fund of Qilu Health and Health Leading Talents Training Project。
文摘Objective The resting-state functional magnetic resonance imaging(rs-f MRI)method was used to observe brain activity and its functional connection upon electroacupuncture stimulation at bilateral uterine acupoints(EX-CA1),as well as to investigate the mechanism of acupuncture in the treatment of gynecological diseases.Methods Twenty-two healthy female subjects were stimulated by electroacupuncture at bilateral uterine acupoints;rs-f MRI data of the brain were acquired and standardized.Degree centrality(DC),amplitude of low-frequency fluctuation(ALFF),and regional homogeneity(ReHo)were used to analyze local spontaneous brain activity via acupuncture.An independent component analysis was used to evaluate the functional connectivity of the resting brain networks after acupuncture.Results Analytical results showed that the neural activity intensity of the precuneus lobe,orbitofrontal cortex,lingual gyrus,amygdala,and posterior central gyrus decreased after acupuncture(voxel P<0.001,cluster P<0.05).Functional connectivity analysis revealed weakened auditory and right frontal-parietal networks(voxel P<0.001,cluster P<0.05),enhanced visual network(voxel P<0.001,cluster P<0.05),and synergistic auditory network and hypothalamic-pituitary system.Conclusion Significant differences in neural activity and functional connectivity in specific brain regions were observed after acupuncture intervention at uterine acupoints;the hypothalamic-pituitary system also showed various active states in different brain regions.It is speculated that the effective mechanism of acupuncture at uterine acupoints is related to the regulation of reproductive hormones,emotional changes,and somatic sensations.Therefore,the methods used in this study could clarify the neural mechanism of uterine-point acupuncture in the treatment of gynecological diseases and may serve as a reference for other studies pertaining to acupuncture.
基金supported by the National Natural Science Foundation of China(No.51865031)the State Key Laboratory of Engines of Tianjin University(No.K2020-05)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.20KJB470014)。
文摘As a miniaturized direct injection(DI)solution,a self-pressurized injector is of great significance for small aviation piston engines,such as spark-ignited two-stroke heavy-fuel engines.The spray characteristics of DI injectors are an important application prerequisite.In this paper,the computational fluid dynamics(CFD)software AVL Fire is employed to study the spray characteristics.Two types of spray models are established based on the Han Sheet model and the KH-RT model,and simulation works are carried out according to two types of spray tests in the literature.The comparison results show that in the constant volume bomb test,the spray patterns obtained by simulation under the two sets of environmental pressures are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray contraction of the near nozzle field and the vortex of the far nozzle field better.In the tube test,the spray patterns obtained by simulation under the five sets of flow velocity are similar to those in the experiment,and the simulation spray using the KH-RT model can fit the spray expansion and the vortex of the far nozzle field better.The RP-3 kerosene spray characteristics of the self-pressurized injector are also experimentally studied,and the results demonstrate that due to the higher viscosity of kerosene,the spray shrinks more easily,resulting in a smaller spray cone angle and larger penetration.Therefore,changes in environmental pressure have greater impact on the kerosene spray pattern.
文摘The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind to hydrogen peroxide and produce an activated complex that can react with a wide range of donor molecules. Therefore inactivation of the enzyme may increase the shelf life of raw and un-blanched frozen vegetables. In order to inactivate of the enzyme several physical and chemical treatments among them heating （blanching）, lowering pH or aw or adding chemical additives can be used, however each of the above mentioned methods has a kind of shortcoming. Our results indicated that crude extract of red cabbage and cabbage has the highest and potato and lettuce has the lowest peroxidase activity respectively （P〈0.05）. Although peroxidase resistance to essential oils varied among different vegetables but clove in all concentration had the best effects in decrease ofperoxidase activity （P〈0.05） whereas cumin and fennel were partially able to reduce the enzyme activity. （P〈0.05）.
基金Project (No. 50806046) supported by the National Natural Science Foundation of China
文摘We proposed the flat-type permanent magnet linear alternator (LA) for free piston linear alternators (FPLAs) instead of the tubular one. Using the finite element method (FEM), we compare these two kinds of LAs. The FEM result shows that the flat-type permanent magnet LA has higher efficiency and larger output specific power than the tubular one, therefore more suitable for FPLAs, and that the alternator design can be optimized with respect to the permanent magnet length as well as the air gap.
