Hyperthyroidism refers to a clinical state that results from inappropriately hight hyroid hormone levels in the tissues;.Ⅰ-131 therapy plays a critical role and provides a remarkable curative effect in targeting thyr...Hyperthyroidism refers to a clinical state that results from inappropriately hight hyroid hormone levels in the tissues;.Ⅰ-131 therapy plays a critical role and provides a remarkable curative effect in targeting thyroid diseases. Thyroid cells can take up isotope I-131, which emits not only beta rays but also展开更多
This study examines whether a group of captive false killer whales(P seudorca crassidens) showed variations in the vocal rate around feeding times. The high level of motivation to express appetitive behaviors in capti...This study examines whether a group of captive false killer whales(P seudorca crassidens) showed variations in the vocal rate around feeding times. The high level of motivation to express appetitive behaviors in captive animals may lead them to respond with changes of the behavioral activities during the time prior to food deliveries which are referred to as food anticipatory activity. False killer whales at Qingdao Polar Ocean World(Qingdao, China) showed signifi cant variations of the rates of both the total sounds and sound classes(whistles, clicks, and burst pulses) around feedings. Precisely, from the Transition interval that recorded the lowest vocalization rate(3.40 s/m/d), the whales increased their acoustic emissions upon trainers' arrival(13.08 s/m/d). The high rate was maintained or intensifi ed throughout the food delivery(25.12 s/m/d), and then reduced immediately after the animals were fed(9.91 s/m/d). These changes in the false killer whales sound production rates around feeding times supports the hypothesis of the presence of a food anticipatory vocal activity. Although sound rates may not give detailed information regarding referential aspects of the animal communication it might still shed light about the arousal levels of the individuals during different social or environmental conditions. Further experiments should be performed to assess if variations of the time of feeding routines may affect the vocal activity of cetaceans in captivity as well as their welfare.展开更多
The importance of education and cultural inheritance is becoming increasingly prominent.Through literature review and empirical research,combining quantitative data and qualitative analysis,this paper assesses the tea...The importance of education and cultural inheritance is becoming increasingly prominent.Through literature review and empirical research,combining quantitative data and qualitative analysis,this paper assesses the teaching methods,curriculum,and student interest and participation in vocal music education in colleges and universities.The study found that vocal music education played a positive role in increasing students’participation in cultural activities,enhancing their identification with traditional music and improving their skills,despite problems such as inadequate teaching systems and homogenized curricula.In particular,the participation rate of students in cultural activities before and after the educational changes increased significantly from 31–54.7%to 62.4–83.6%,indicating that vocal music education can effectively stimulate students’enthusiasm for cultural participation.In addition,the strengthening of the teaching staff and innovations in teaching methods,such as the application of multimedia and virtual reality technologies,provide students with richer learning experiences and personalized learning paths.展开更多
Two kinds of methods for determining seismic parameters are presented, that is, the potential seismic source zoning method and grid-spatially smoothing method. The Gaussian smoothing method and the modified Gaussian s...Two kinds of methods for determining seismic parameters are presented, that is, the potential seismic source zoning method and grid-spatially smoothing method. The Gaussian smoothing method and the modified Gaussian smoothing method are described in detail, and a comprehensive analysis of the advantages and disadvantages of these methods is made. Then, we take centrai China as the study region, and use the Gaussian smoothing method and potential seismic source zoning method to build seismic models to calculate the mean annual seismic rate. Seismic hazard is calculated using the probabilistic seismic hazard analysis method to construct the ground motion acceleration zoning maps. The differences between the maps and these models are discussed and the causes are investigated. The results show that the spatial smoothing method is suitable for estimating the seismic hazard over the moderate and low seismicity regions or the hazard caused by background seismicity; while the potential seismic source zoning method is suitable for estimating the seismic hazard in well-defined seismotectonics. Combining the spatial smoothing method and the potential seismic source zoning method with an integrated account of the seismicity and known seismotectonics is a feasible approach to estimate the seismic hazard in moderate and low seismicity regions.展开更多
Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation.The activation rate refers to the ratio of activated impurity number to the total impurity...Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation.The activation rate refers to the ratio of activated impurity number to the total impurity number in the sample.After injecting phosphorus with the dose and energy(energy=55 keV,dose=3×10^(15) cm^(-2)),the samples were annealed at different temperatures,and laser irradiation experiments were performed after annealing.The experimental results showed that the activation rate of phosphorus was the highest at 850℃,and the highest activation rate was 67%.Upon femtosecond laser irradiation samples after thermal annealing,while keeping the crystalline silicon surface without damage,the activation rate was improved.When the energy-flux density of the femtosecond laser was 0.65 kJ/cm2,the activation rate was the highest,increasing from 67%to 74.81%.展开更多
A newly designed pneumatic spring with two separate chambers is promoted and double-loop active control is introduced to overcome the following drawbacks of passive pneumatic isolation: ① The low frequency resonance...A newly designed pneumatic spring with two separate chambers is promoted and double-loop active control is introduced to overcome the following drawbacks of passive pneumatic isolation: ① The low frequency resonances introduced into the system; ② Conflict between lower isolation frequency and stiffness high enough to limit quasi-static stroke;③ Inconsistent isolation level with different force load. The design of two separate chambers is for the purpose of tuning support frequency and force independently and each chamber is controlled by a different valve. The inner one of double-loop structure is pressure control, and in order to obtain good performance, nonlinearities compensation and motion flow rate compensation (MFRC) are added besides the basic cascade compensation, and the influence of tube length is studied. The outer loop has two functions: one is to eliminate the resonance caused by isolation support and to broaden the isolation frequency band by payload velocity feedback and base velocity feed forward, and the other is to tune support force and support stiffness simultaneously and independently, which means the support force will have no effect on support stiffness. Theoretical analysis and experiment results show that the three drawbacks are overcome simultaneously.展开更多
The fault system of Liaodong Bay developed extensively under the control of the Tanlu Fault. The fault system can be grouped into strike-slip faults of grade Ⅰ, trunk faults of grade Ⅱand branch faults (induced fau...The fault system of Liaodong Bay developed extensively under the control of the Tanlu Fault. The fault system can be grouped into strike-slip faults of grade Ⅰ, trunk faults of grade Ⅱand branch faults (induced faults) of grade Ⅲ respectively based on its developmental scale. The faults of grade Ⅰ and Ⅱwere deep, early and large while the faults of grade Ⅲwere shallow, late and small. The formation, evolution and distribution features played a significant role in controlling the migration of oil and gas in both horizontal and vertical directions. The fluid transfer in the fault system occurred in the process of faulting. The strike-slip and trunk faults moved actively forming predominant pathways for oil and gas migration. The branch faults, with weak activity, generally controlled the development of traps and were beneficial for the accumulation and preservation of oil and gas. The faults of grade Ⅰ and Ⅱ formed the major migration pathways for oil and gas, but their fault activity rates appeared to vary along their strikes. The zones with a relatively low fault activity rate might be favorable for oil and gas accumulation. When the activities of strike-slip, trunk, and branch faults came to a halt, the fault seal behavior had a vitally important effect on the accumulation of oil and gas. The controlling role of the fault over fluid distribution was further analyzed by calculating the fault activity quantitatively.展开更多
The earthquake that occurred on May 12, 2008, in Wenchuan County aroused a great deal of research on co-seismic landslide susceptibility assessment, but there is still a lack of an evaluation method that considers the...The earthquake that occurred on May 12, 2008, in Wenchuan County aroused a great deal of research on co-seismic landslide susceptibility assessment, but there is still a lack of an evaluation method that considers the activity state of the landslide itself. Therefore, this paper establishes a new susceptibility evaluation model that superimposes the active landslide state based on previous susceptibility evaluation models. Based on a multi-phase landslide database, the probabilistic approach was used to evaluate landslide susceptibility in the Miansi town over many years. We chose the elevation, slope, aspect, and distance from the channel as trigger factors and then used the probability comprehensive discrimination method to calculate the probability of landslide occurrence. Then, the susceptibility results of each period were calculated by superposition with the activity rate. The results show that between 2008 and 2014, the proportion of areas with low landslide susceptibility in the study area was the largest, and the proportionof areas with the highest susceptibility was minimal. The landslide area with highest susceptibility gradually decreased from 2014 to 2017. However, in 2017, 15.06% of the area was still with high susceptibility, and relevant disaster prevention and reduction measures should be taken in these areas. The larger area under the receiver operating characteristic curve(AUC) indicates that the results of the landslide susceptibility assessment in this study are more objective and reliable than those of previous models. The difference in the AUC values over many years shows that the accuracy of the evaluation results of this model is not constant, and a greater number of landslides or higher landslide activity corresponds to a higher accuracy of the evaluation results.展开更多
The current earthquake forecast algorithms are not free of shortcomings due to inherent limitations.Especially,the requirement of stationarity in the evaluation of earthquake time series as a prerequisite,significantl...The current earthquake forecast algorithms are not free of shortcomings due to inherent limitations.Especially,the requirement of stationarity in the evaluation of earthquake time series as a prerequisite,significantly limits the use of forecast algorithms to areas where stationary data is not available.Another shortcoming of forecast algorithms is the ergodicity assumption,which states that certain characteristics of seismicity are spatially invariant.In this study,a new earthquake forecast approach is introduced for the locations where stationary data are not available.For this purpose,the spatial activity rate density for each spatial unit is evaluated as a parameter of a Markov chain.The temporal pattern is identified by setting the states at certain spatial activity rate densities.By using the transition patterns between the states,1-and 5-year forecasts were computed.The method is suggested as an alternative and complementary to the existing methods by proposing a solution to the issues of ergodicity and stationarity assumptions at the same time.展开更多
An equivalent amount of metallurgical slag, water-quenched slag powder and activator was substituted for a part of cement to prepare concretes at strength grades ofC25, C30 and C40. Thanks to the filling effect, pozzo...An equivalent amount of metallurgical slag, water-quenched slag powder and activator was substituted for a part of cement to prepare concretes at strength grades ofC25, C30 and C40. Thanks to the filling effect, pozzolanic effect, raicro-aggregate effect, and improvement of pore structure, the prepared concretes not only had greater strength compared with reference concrete, but also had greater impermeability and frost-resistance. Moreover, the expansion reactions between alkali and aggregates were effectively inhibited. The slag and activator can serve as the raw materials for green concretes.展开更多
The bactericidal effect on the representative type of Gram-negative Escherichia coli(E.coli) and Gram-positive Bacillus subtilis in drinking water was investigated in this paper by using dielectric barrier discharge...The bactericidal effect on the representative type of Gram-negative Escherichia coli(E.coli) and Gram-positive Bacillus subtilis in drinking water was investigated in this paper by using dielectric barrier discharge(DBD) advanced oxidation technology.The sterilizing rates under different conditions of reaction time t,input voltage V,p H value,and initial concentration of bacteria C_0 were investigated to figure out the optimum sterilization conditions.Our observations and comparisons of cell morphology alteration by scanning electron microscopy and transmission electron microscopy revealed the sterilization mechanisms.The results showed that the sterilizing rate increased obviously with the extension of reaction time t and the rise of input voltage V.The optimal sterilization effect was achieved when the p H value was 7.1.As the initial concentration of bacteria rose,the sterilizing rate decreased.When the input voltage was 2.2 k V and the initial concentration of bacteria was relatively low,the sterilizing rate almost reached 100% after a certain treatment time in neutral aqueous solution.The reasons for the great damage of cell structure and the killing of bacteria are the oxidation of O_3,OH and the accumulation of active species produced by DBD.The article provides a certain theoretical and experimental basis for DBD application in water pollution treatment.展开更多
North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment(GRACE) gravity data from 2009 to 2013 are used to calculate the gravity change r...North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment(GRACE) gravity data from 2009 to 2013 are used to calculate the gravity change rate(GCR) using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji(Beijing-Tianjin-Hebei Province), and Bohai Bay Basin(BBB) regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be "negativepositive-negative" from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage.展开更多
An active front steering (AFS) intervention control during braking for vehicle stability is presented. Based on the investigation of AFS mechanism, a simplified model of steering system is established and integrated...An active front steering (AFS) intervention control during braking for vehicle stability is presented. Based on the investigation of AFS mechanism, a simplified model of steering system is established and integrated with vehicle model. Then the AFS control on vehicle handling dynamics during braking is designed. Due to the difficulties associated with the sideslip angle measurement of vehicle, a state observer is designed to provide real time estimation. Thereafter, the controller with the feedback of both sideslip and yaw angle is implemented. To evaluate the system control, the proposed AFS controlled vehicle has been tested in the Hardware-in-the-loop-simulation (HILS) system and compared with that of conventional vehicle. Results show that AFS can improve vehicle lateral stability effectively without reducing the braking performance.展开更多
In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy(SEM), energy dispersive s...In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy(SEM), energy dispersive spectrometry(EDS) and X-ray diffraction(XRD) were employed to investigate the microstructures and phase constitutions of the coatings. The experimental results show that all silicon deposition coatings have multi-layer structure. The microstructure and composition of silicide coatings strongly depend on siliconizing temperatures. In order to investigate the rate controlling step of pack siliconizing on Ti Al alloy, coating growth kinetics was analyzed by measuring the mass gains per unit area of silicided samples as a function of time and temperature. The results showed that the rate controlling step was gas-phase diffusion step and the growth rate constant(k) ranged from 1.53 mg^2/(cm^4·h^2) to 2.3 mg^2/(cm^4·h^2). Activation energy(Q) for the process was calculated as 109 k J/mol, determined by Arrhenius' equation: k = k0 exp[–Q/(RT)].展开更多
The subject of this study is strike-slip fault zones, where temporal variations of accumulation in strike-slip deformation complicate the standard process of deformation accu- mulation and release during strong earthq...The subject of this study is strike-slip fault zones, where temporal variations of accumulation in strike-slip deformation complicate the standard process of deformation accu- mulation and release during strong earthquakes. These temporal variations are expressed in the E1 Ghab segment of the Dead Sea Transform zone (DST, Eastern Mediterranean) and in the Talas-Fergana fault zone (Central Asia). According to Global Positioning System (GPS) data, the strike-slip deformations within these zones are not now accumulating or are accumulating at a rate that is significantly less than their average rate during the Holocene and Quaternary or the Pliocene-Quaternary. Simultaneously, weak transverse shortening has been measured in both zones by GPS. In both of these zones, strong earthquakes have not registered within the XX century, yet epochs of intensified seismicity (strong earthquakes) took place throughout history. In the southern and central parts of the E1 Ghab zone, there is evidence of 30 strong historical earthquakes of Ms ≥ 5.7; however, no instrumental earthquakes of Ms 〉 5 have been identified. The temporal distribution of seismic energy released by these earthquakes demonstrates a 350 ± 50-year cycle. Values for the seismic energies released during the peak phases of these cycles are approximated by a sinusoid that suggests the possibility of a 〉1800-year cycle ("hyper-cycle"), which began around the 3rd century, reached its maximum in the 12th century, and has continued until now. A combination of geological, archaeoseismological, and geodetic data show that the rate of sinistral strike-slip deformation varied in the fault zone, probably in conformity with the variation of seismicity during the "hyper-cycle." In the Talas-Fergana fault zone, trenching and 14C dating that was correlated with right lateral offsets, gave a possible preliminary estimate of the average rates of the Late Holocene strike slip of about 10 mm per year, with a decrease in the SE direction to 4 mm-4.5 mm per year. These studies also showed that the slip in the Talas-Fergana fault zone was realized mainly during strong earthquakes. New trenching and 14C dating of paleoearthquake records identified the epoch of seismicity intensification dating to the XIV-XVII centuries. These paleoearthquakes could produce a total dextral slip at several meters. Therefore, consid- eration of these epochs was necessary to determine a calculated average slip rate during the Late Holocene.展开更多
Traditionally the deformation resistance in creep is characterized by the minimum creep rate εmin and its sensitivity to stress (stress exponent n) and temperature (activation energy Q). Various values of constan...Traditionally the deformation resistance in creep is characterized by the minimum creep rate εmin and its sensitivity to stress (stress exponent n) and temperature (activation energy Q). Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for εmin. in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile εmin. result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile εmin, and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.展开更多
The doping dependence of dry thermal oxidation rates in n-type 6H-SiC was studied. The oxidation temperature ranged from 1050 to 1150℃ and the nitrogen doping concentration ranged from 9.53× 10^16, 1.44× 10...The doping dependence of dry thermal oxidation rates in n-type 6H-SiC was studied. The oxidation temperature ranged from 1050 to 1150℃ and the nitrogen doping concentration ranged from 9.53× 10^16, 1.44× 10^17, to 2.68×10^18 cm ^3. By combining the modified deal-grove model and Arrhenius equation, the linear and parabolic rate constants, and their corresponding activation energies were extracted. The results show that: higher temperature corresponded to thicker oxides; dry thermal oxidation rate in n-type 6H-SiC depended on the doping concentration; both linear-rate-constant and parabolic-rate-constant increased with the doping concentration; the parabolic activation energy increased from 0.082 to 0.104 e V, both linear and parabolic activation energies increasing with the doping concentration; and, the parabolic pre-exponential factor increased from 2.6 ×10^4 to 2.7 ×10^5nm^2/s, both linear and parabolic pre-exponential factor increasing with doping concentration. Moreover, the experiment also illustrated that it is unreasonable to use a variation of the Arrhenius activation energy to explain the doping dependence of thermal oxidation on SiC.展开更多
Aviation spraying is one of the most important methods for the treatment of forestry pests and diseases,which has a high operation efficiency and effectiveness.The combination of aviation spray and biological pesticid...Aviation spraying is one of the most important methods for the treatment of forestry pests and diseases,which has a high operation efficiency and effectiveness.The combination of aviation spray and biological pesticides to reduce the impact of pesticide spray on environment has become an important development in the direction of agricultural aviation.In order to explore the effects of aviation spray parameters on particle size distribution and activity retention of biological pesticide droplets,a system of droplets size test and an activity retention rate test system of biological pesticides were constructed.The related experiments were conducted by changing the structural parameters of the rotary cage nozzle(the diameter of nozzle)and the technical parameters of the operation(rotary speed and flow rate).The results showed that the average relative width S of the droplets of the rotary cage nozzle was close to 1,and the droplet distribution was uniform.The influence factors on the particle size distribution of biological pesticide droplets were rotary speed,nozzle diameter,medium and flow rate in descending order.The rotary speed,nozzle diameter,and medium had a significant influence on droplet size distribution.The average activity retention rate of Bacillus thuringiensis was 88.83%,and the germination rate of Beauveria bassiana was 89.80%.The rotary speed had a significant effect on the activity retention rate of bacterial and fungal biological pesticides,and it was negatively correlated.The rotary speed was between 3000-5000 r/min,and the activity retention rate was higher.The research results can provide guidance for spraying biological pesticides in aerial plant protection operations with rotary cage nozzle.展开更多
Very few selected species of primates are known to be capable of entering torpor. This exciting discovery means that the ability to enter a natural state of dormancy is an ancestral trait among primates and, in phylog...Very few selected species of primates are known to be capable of entering torpor. This exciting discovery means that the ability to enter a natural state of dormancy is an ancestral trait among primates and, in phylogenetic terms, is very close to the human lineage. To explore the regulatory mechanisms that underlie primate torpor, we analyzed signal transduction cascades to discover those involved in coordinating tissue responses during torpor. The responses of mitogen-activated protein kinase(MAPK) family members to primate torpor were compared in six organs of control(aroused) versus torpid gray mouse lemurs, Microcebus murinus. The proteins examined include extracellular signal-regulated kinases(ERKs), c-jun NH2-terminal kinases(JNKs), MAPK kinase(MEK), and p38, in addition to stress-related proteins p53 and heat shock protein 27(HSP27). The activation of specific MAPK signal transduction pathways may provide a mechanism to regulate the expression of torpor-responsive genes or the regulation of selected downstream cellular processes. In response to torpor, each MAPK subfamily responded differently during torpor and each showed organ-specific patterns of response. For example, skeletal muscle displayed elevated relative phosphorylation of ERK1/2 during torpor. Interestingly, adipose tissues showed the highest degree of MAPK activation. Brown adipose tissue displayed an activation of ERK1/2 and p38, whereas white adipose tissue showed activation of ERK1/2, p38, MEK, and JNK during torpor. Importantly, both adipose tissues possess specialized functions that are critical for torpor, with brown adipose required for non-shivering thermogenesis and white adipose utilized as the primary source of lipid fuel for torpor. Overall, these data indicate crucial roles of MAPKs in the regulation of primate organs during torpor.展开更多
The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activa...The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100kHz (interval by 20kHz) and 10-50W (interval by 10W), respectively. The experimental clata indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.展开更多
基金supported by a fund from the Key Project of Natural Science Foundation of Tianjin [16JCZDJC36100]Medical and Health Technology Innovation Project of the Chinese Academy of Medical Sciences [2017-I2M-1-016]+2 种基金Fundamental Research Funds for the Central Universities [3332018116]PUMC Youth Fund [3332015101]Fundamental Research Funds for CAMS&PUMC [2016ZX310074]
文摘Hyperthyroidism refers to a clinical state that results from inappropriately hight hyroid hormone levels in the tissues;.Ⅰ-131 therapy plays a critical role and provides a remarkable curative effect in targeting thyroid diseases. Thyroid cells can take up isotope I-131, which emits not only beta rays but also
基金Supported by grants from the Institute of Hydrobiology,Chinese Academy of Sciences
文摘This study examines whether a group of captive false killer whales(P seudorca crassidens) showed variations in the vocal rate around feeding times. The high level of motivation to express appetitive behaviors in captive animals may lead them to respond with changes of the behavioral activities during the time prior to food deliveries which are referred to as food anticipatory activity. False killer whales at Qingdao Polar Ocean World(Qingdao, China) showed signifi cant variations of the rates of both the total sounds and sound classes(whistles, clicks, and burst pulses) around feedings. Precisely, from the Transition interval that recorded the lowest vocalization rate(3.40 s/m/d), the whales increased their acoustic emissions upon trainers' arrival(13.08 s/m/d). The high rate was maintained or intensifi ed throughout the food delivery(25.12 s/m/d), and then reduced immediately after the animals were fed(9.91 s/m/d). These changes in the false killer whales sound production rates around feeding times supports the hypothesis of the presence of a food anticipatory vocal activity. Although sound rates may not give detailed information regarding referential aspects of the animal communication it might still shed light about the arousal levels of the individuals during different social or environmental conditions. Further experiments should be performed to assess if variations of the time of feeding routines may affect the vocal activity of cetaceans in captivity as well as their welfare.
文摘The importance of education and cultural inheritance is becoming increasingly prominent.Through literature review and empirical research,combining quantitative data and qualitative analysis,this paper assesses the teaching methods,curriculum,and student interest and participation in vocal music education in colleges and universities.The study found that vocal music education played a positive role in increasing students’participation in cultural activities,enhancing their identification with traditional music and improving their skills,despite problems such as inadequate teaching systems and homogenized curricula.In particular,the participation rate of students in cultural activities before and after the educational changes increased significantly from 31–54.7%to 62.4–83.6%,indicating that vocal music education can effectively stimulate students’enthusiasm for cultural participation.In addition,the strengthening of the teaching staff and innovations in teaching methods,such as the application of multimedia and virtual reality technologies,provide students with richer learning experiences and personalized learning paths.
基金sponsored by the National Key Technology R&D Program,China (2006BAC13B01)
文摘Two kinds of methods for determining seismic parameters are presented, that is, the potential seismic source zoning method and grid-spatially smoothing method. The Gaussian smoothing method and the modified Gaussian smoothing method are described in detail, and a comprehensive analysis of the advantages and disadvantages of these methods is made. Then, we take centrai China as the study region, and use the Gaussian smoothing method and potential seismic source zoning method to build seismic models to calculate the mean annual seismic rate. Seismic hazard is calculated using the probabilistic seismic hazard analysis method to construct the ground motion acceleration zoning maps. The differences between the maps and these models are discussed and the causes are investigated. The results show that the spatial smoothing method is suitable for estimating the seismic hazard over the moderate and low seismicity regions or the hazard caused by background seismicity; while the potential seismic source zoning method is suitable for estimating the seismic hazard in well-defined seismotectonics. Combining the spatial smoothing method and the potential seismic source zoning method with an integrated account of the seismicity and known seismotectonics is a feasible approach to estimate the seismic hazard in moderate and low seismicity regions.
基金supported by National Key R&D Program of China (No. 2018YFB1500500).
文摘Thermal annealing and laser irradiation were used to study the activation rate of phosphorus in silicon after ion implantation.The activation rate refers to the ratio of activated impurity number to the total impurity number in the sample.After injecting phosphorus with the dose and energy(energy=55 keV,dose=3×10^(15) cm^(-2)),the samples were annealed at different temperatures,and laser irradiation experiments were performed after annealing.The experimental results showed that the activation rate of phosphorus was the highest at 850℃,and the highest activation rate was 67%.Upon femtosecond laser irradiation samples after thermal annealing,while keeping the crystalline silicon surface without damage,the activation rate was improved.When the energy-flux density of the femtosecond laser was 0.65 kJ/cm2,the activation rate was the highest,increasing from 67%to 74.81%.
基金This project is supported by Commission of Science Technology and Industry for National Defense, China.
文摘A newly designed pneumatic spring with two separate chambers is promoted and double-loop active control is introduced to overcome the following drawbacks of passive pneumatic isolation: ① The low frequency resonances introduced into the system; ② Conflict between lower isolation frequency and stiffness high enough to limit quasi-static stroke;③ Inconsistent isolation level with different force load. The design of two separate chambers is for the purpose of tuning support frequency and force independently and each chamber is controlled by a different valve. The inner one of double-loop structure is pressure control, and in order to obtain good performance, nonlinearities compensation and motion flow rate compensation (MFRC) are added besides the basic cascade compensation, and the influence of tube length is studied. The outer loop has two functions: one is to eliminate the resonance caused by isolation support and to broaden the isolation frequency band by payload velocity feedback and base velocity feed forward, and the other is to tune support force and support stiffness simultaneously and independently, which means the support force will have no effect on support stiffness. Theoretical analysis and experiment results show that the three drawbacks are overcome simultaneously.
文摘The fault system of Liaodong Bay developed extensively under the control of the Tanlu Fault. The fault system can be grouped into strike-slip faults of grade Ⅰ, trunk faults of grade Ⅱand branch faults (induced faults) of grade Ⅲ respectively based on its developmental scale. The faults of grade Ⅰ and Ⅱwere deep, early and large while the faults of grade Ⅲwere shallow, late and small. The formation, evolution and distribution features played a significant role in controlling the migration of oil and gas in both horizontal and vertical directions. The fluid transfer in the fault system occurred in the process of faulting. The strike-slip and trunk faults moved actively forming predominant pathways for oil and gas migration. The branch faults, with weak activity, generally controlled the development of traps and were beneficial for the accumulation and preservation of oil and gas. The faults of grade Ⅰ and Ⅱ formed the major migration pathways for oil and gas, but their fault activity rates appeared to vary along their strikes. The zones with a relatively low fault activity rate might be favorable for oil and gas accumulation. When the activities of strike-slip, trunk, and branch faults came to a halt, the fault seal behavior had a vitally important effect on the accumulation of oil and gas. The controlling role of the fault over fluid distribution was further analyzed by calculating the fault activity quantitatively.
基金financially supported by the National Key Research and Development Program of China(Grant No.2017YFC1501004)the National Natural Science Foundation of China(Grant No.41672299)research fund of the State Key Laboratory of Geo-Hazard Prevention and Geo-Environment Protection(Grant No.SKLGP2017Z002)
文摘The earthquake that occurred on May 12, 2008, in Wenchuan County aroused a great deal of research on co-seismic landslide susceptibility assessment, but there is still a lack of an evaluation method that considers the activity state of the landslide itself. Therefore, this paper establishes a new susceptibility evaluation model that superimposes the active landslide state based on previous susceptibility evaluation models. Based on a multi-phase landslide database, the probabilistic approach was used to evaluate landslide susceptibility in the Miansi town over many years. We chose the elevation, slope, aspect, and distance from the channel as trigger factors and then used the probability comprehensive discrimination method to calculate the probability of landslide occurrence. Then, the susceptibility results of each period were calculated by superposition with the activity rate. The results show that between 2008 and 2014, the proportion of areas with low landslide susceptibility in the study area was the largest, and the proportionof areas with the highest susceptibility was minimal. The landslide area with highest susceptibility gradually decreased from 2014 to 2017. However, in 2017, 15.06% of the area was still with high susceptibility, and relevant disaster prevention and reduction measures should be taken in these areas. The larger area under the receiver operating characteristic curve(AUC) indicates that the results of the landslide susceptibility assessment in this study are more objective and reliable than those of previous models. The difference in the AUC values over many years shows that the accuracy of the evaluation results of this model is not constant, and a greater number of landslides or higher landslide activity corresponds to a higher accuracy of the evaluation results.
文摘The current earthquake forecast algorithms are not free of shortcomings due to inherent limitations.Especially,the requirement of stationarity in the evaluation of earthquake time series as a prerequisite,significantly limits the use of forecast algorithms to areas where stationary data is not available.Another shortcoming of forecast algorithms is the ergodicity assumption,which states that certain characteristics of seismicity are spatially invariant.In this study,a new earthquake forecast approach is introduced for the locations where stationary data are not available.For this purpose,the spatial activity rate density for each spatial unit is evaluated as a parameter of a Markov chain.The temporal pattern is identified by setting the states at certain spatial activity rate densities.By using the transition patterns between the states,1-and 5-year forecasts were computed.The method is suggested as an alternative and complementary to the existing methods by proposing a solution to the issues of ergodicity and stationarity assumptions at the same time.
文摘An equivalent amount of metallurgical slag, water-quenched slag powder and activator was substituted for a part of cement to prepare concretes at strength grades ofC25, C30 and C40. Thanks to the filling effect, pozzolanic effect, raicro-aggregate effect, and improvement of pore structure, the prepared concretes not only had greater strength compared with reference concrete, but also had greater impermeability and frost-resistance. Moreover, the expansion reactions between alkali and aggregates were effectively inhibited. The slag and activator can serve as the raw materials for green concretes.
基金supported by the Science and Technology Support Project Plan and Social Development of Jiangsu Province,China(No.BE2011732)the Science and Technology Support Project Plan and Social Development of Zhenjiang,Jiangsu Province,China(No.SH2012013)
文摘The bactericidal effect on the representative type of Gram-negative Escherichia coli(E.coli) and Gram-positive Bacillus subtilis in drinking water was investigated in this paper by using dielectric barrier discharge(DBD) advanced oxidation technology.The sterilizing rates under different conditions of reaction time t,input voltage V,p H value,and initial concentration of bacteria C_0 were investigated to figure out the optimum sterilization conditions.Our observations and comparisons of cell morphology alteration by scanning electron microscopy and transmission electron microscopy revealed the sterilization mechanisms.The results showed that the sterilizing rate increased obviously with the extension of reaction time t and the rise of input voltage V.The optimal sterilization effect was achieved when the p H value was 7.1.As the initial concentration of bacteria rose,the sterilizing rate decreased.When the input voltage was 2.2 k V and the initial concentration of bacteria was relatively low,the sterilizing rate almost reached 100% after a certain treatment time in neutral aqueous solution.The reasons for the great damage of cell structure and the killing of bacteria are the oxidation of O_3,OH and the accumulation of active species produced by DBD.The article provides a certain theoretical and experimental basis for DBD application in water pollution treatment.
基金supported by the National Natural Science Foundation of China(41304060)the national key basic research and development plan(2013CB733304)
文摘North China is a key region for studying geophysical progress. In this study, ground-based and Gravity Recovery and Climate Experiment(GRACE) gravity data from 2009 to 2013 are used to calculate the gravity change rate(GCR) using the polynomial fitting method. In general, the study area was divided into the Shanxi rift, Jing-Jin-Ji(Beijing-Tianjin-Hebei Province), and Bohai Bay Basin(BBB) regions. Results of the distribution of the GCR determined from ground-based gravimetry show that the GCR appears to be "negativepositive-negative" from west to east, which indicates that different geophysical mechanisms are involved in the tectonic activities of these regions. However, GRACE solutions are conducted over a larger spatial scale and are able to show a difference between southern and northern areas and a mass redistribution of land water storage.
文摘An active front steering (AFS) intervention control during braking for vehicle stability is presented. Based on the investigation of AFS mechanism, a simplified model of steering system is established and integrated with vehicle model. Then the AFS control on vehicle handling dynamics during braking is designed. Due to the difficulties associated with the sideslip angle measurement of vehicle, a state observer is designed to provide real time estimation. Thereafter, the controller with the feedback of both sideslip and yaw angle is implemented. To evaluate the system control, the proposed AFS controlled vehicle has been tested in the Hardware-in-the-loop-simulation (HILS) system and compared with that of conventional vehicle. Results show that AFS can improve vehicle lateral stability effectively without reducing the braking performance.
基金Funded by the Natural Science Program for Basic Research in Key Areas of Shaanxi Province(2014JZ012)
文摘In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy(SEM), energy dispersive spectrometry(EDS) and X-ray diffraction(XRD) were employed to investigate the microstructures and phase constitutions of the coatings. The experimental results show that all silicon deposition coatings have multi-layer structure. The microstructure and composition of silicide coatings strongly depend on siliconizing temperatures. In order to investigate the rate controlling step of pack siliconizing on Ti Al alloy, coating growth kinetics was analyzed by measuring the mass gains per unit area of silicided samples as a function of time and temperature. The results showed that the rate controlling step was gas-phase diffusion step and the growth rate constant(k) ranged from 1.53 mg^2/(cm^4·h^2) to 2.3 mg^2/(cm^4·h^2). Activation energy(Q) for the process was calculated as 109 k J/mol, determined by Arrhenius' equation: k = k0 exp[–Q/(RT)].
基金supported by the Division of Earth Sciences,Russian Academy of Sciences(6),and the Russian Foundation for Basic Research(14-05-00122)
文摘The subject of this study is strike-slip fault zones, where temporal variations of accumulation in strike-slip deformation complicate the standard process of deformation accu- mulation and release during strong earthquakes. These temporal variations are expressed in the E1 Ghab segment of the Dead Sea Transform zone (DST, Eastern Mediterranean) and in the Talas-Fergana fault zone (Central Asia). According to Global Positioning System (GPS) data, the strike-slip deformations within these zones are not now accumulating or are accumulating at a rate that is significantly less than their average rate during the Holocene and Quaternary or the Pliocene-Quaternary. Simultaneously, weak transverse shortening has been measured in both zones by GPS. In both of these zones, strong earthquakes have not registered within the XX century, yet epochs of intensified seismicity (strong earthquakes) took place throughout history. In the southern and central parts of the E1 Ghab zone, there is evidence of 30 strong historical earthquakes of Ms ≥ 5.7; however, no instrumental earthquakes of Ms 〉 5 have been identified. The temporal distribution of seismic energy released by these earthquakes demonstrates a 350 ± 50-year cycle. Values for the seismic energies released during the peak phases of these cycles are approximated by a sinusoid that suggests the possibility of a 〉1800-year cycle ("hyper-cycle"), which began around the 3rd century, reached its maximum in the 12th century, and has continued until now. A combination of geological, archaeoseismological, and geodetic data show that the rate of sinistral strike-slip deformation varied in the fault zone, probably in conformity with the variation of seismicity during the "hyper-cycle." In the Talas-Fergana fault zone, trenching and 14C dating that was correlated with right lateral offsets, gave a possible preliminary estimate of the average rates of the Late Holocene strike slip of about 10 mm per year, with a decrease in the SE direction to 4 mm-4.5 mm per year. These studies also showed that the slip in the Talas-Fergana fault zone was realized mainly during strong earthquakes. New trenching and 14C dating of paleoearthquake records identified the epoch of seismicity intensification dating to the XIV-XVII centuries. These paleoearthquakes could produce a total dextral slip at several meters. Therefore, consid- eration of these epochs was necessary to determine a calculated average slip rate during the Late Holocene.
基金supported by the project CZ.1.05/1.1.00/02.0068 granted by the European Regional Development Fund
文摘Traditionally the deformation resistance in creep is characterized by the minimum creep rate εmin and its sensitivity to stress (stress exponent n) and temperature (activation energy Q). Various values of constant n have been reported in the literature and interpreted in terms of specific mechanisms. The present case study of coarse-grained Cu at 573 K yields a stress exponent n = 9 for εmin. in tension and a relatively low activation energy. The evolution of the deformation resistance with strain at constant tensile creep load and comparison with creep in compression without fracture indicates that the tensile εmin. result from transition from uniform deformation to strain localization during fracture. This is confirmed by the results of creep in compression where fracture is suppressed. Both the tensile εmin, and the compressive creep rate at strains around 0.3 can be described using existing equations for quasi-stationary deformation containing the subgrain boundary misorientation θ as structure parameter. While in the latter case constant θ leads to monotonic increase of n with stress, the tensile nine-power-law results from variable θ, and has no simple meaning. The result of this case study means that uncritical interpretation of minimum tensile creep rates as stationary ones bears a high risk of systematic errors in the determination of creep parameters and identification of creep mechanisms.
基金Project supported by the National Natural Science Foundation of China(No.F040405)
文摘The doping dependence of dry thermal oxidation rates in n-type 6H-SiC was studied. The oxidation temperature ranged from 1050 to 1150℃ and the nitrogen doping concentration ranged from 9.53× 10^16, 1.44× 10^17, to 2.68×10^18 cm ^3. By combining the modified deal-grove model and Arrhenius equation, the linear and parabolic rate constants, and their corresponding activation energies were extracted. The results show that: higher temperature corresponded to thicker oxides; dry thermal oxidation rate in n-type 6H-SiC depended on the doping concentration; both linear-rate-constant and parabolic-rate-constant increased with the doping concentration; the parabolic activation energy increased from 0.082 to 0.104 e V, both linear and parabolic activation energies increasing with the doping concentration; and, the parabolic pre-exponential factor increased from 2.6 ×10^4 to 2.7 ×10^5nm^2/s, both linear and parabolic pre-exponential factor increasing with doping concentration. Moreover, the experiment also illustrated that it is unreasonable to use a variation of the Arrhenius activation energy to explain the doping dependence of thermal oxidation on SiC.
基金The research was funded by the National Key Research and Development Program of the 13th Five-Year Plan(Project No.2018YFC1200400,and Project No.2018YFD0600202).
文摘Aviation spraying is one of the most important methods for the treatment of forestry pests and diseases,which has a high operation efficiency and effectiveness.The combination of aviation spray and biological pesticides to reduce the impact of pesticide spray on environment has become an important development in the direction of agricultural aviation.In order to explore the effects of aviation spray parameters on particle size distribution and activity retention of biological pesticide droplets,a system of droplets size test and an activity retention rate test system of biological pesticides were constructed.The related experiments were conducted by changing the structural parameters of the rotary cage nozzle(the diameter of nozzle)and the technical parameters of the operation(rotary speed and flow rate).The results showed that the average relative width S of the droplets of the rotary cage nozzle was close to 1,and the droplet distribution was uniform.The influence factors on the particle size distribution of biological pesticide droplets were rotary speed,nozzle diameter,medium and flow rate in descending order.The rotary speed,nozzle diameter,and medium had a significant influence on droplet size distribution.The average activity retention rate of Bacillus thuringiensis was 88.83%,and the germination rate of Beauveria bassiana was 89.80%.The rotary speed had a significant effect on the activity retention rate of bacterial and fungal biological pesticides,and it was negatively correlated.The rotary speed was between 3000-5000 r/min,and the activity retention rate was higher.The research results can provide guidance for spraying biological pesticides in aerial plant protection operations with rotary cage nozzle.
基金supported by a Discovery grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada (Grant No. 6793)a grant from the Heart and Stroke Foundation of Canada (Grant No. G-140005874) to KBS. KBS holds the Canada Research Chair in Molecular PhysiologyKKB, CWW, and SNT all held NSERC postgraduate scholarships
文摘Very few selected species of primates are known to be capable of entering torpor. This exciting discovery means that the ability to enter a natural state of dormancy is an ancestral trait among primates and, in phylogenetic terms, is very close to the human lineage. To explore the regulatory mechanisms that underlie primate torpor, we analyzed signal transduction cascades to discover those involved in coordinating tissue responses during torpor. The responses of mitogen-activated protein kinase(MAPK) family members to primate torpor were compared in six organs of control(aroused) versus torpid gray mouse lemurs, Microcebus murinus. The proteins examined include extracellular signal-regulated kinases(ERKs), c-jun NH2-terminal kinases(JNKs), MAPK kinase(MEK), and p38, in addition to stress-related proteins p53 and heat shock protein 27(HSP27). The activation of specific MAPK signal transduction pathways may provide a mechanism to regulate the expression of torpor-responsive genes or the regulation of selected downstream cellular processes. In response to torpor, each MAPK subfamily responded differently during torpor and each showed organ-specific patterns of response. For example, skeletal muscle displayed elevated relative phosphorylation of ERK1/2 during torpor. Interestingly, adipose tissues showed the highest degree of MAPK activation. Brown adipose tissue displayed an activation of ERK1/2 and p38, whereas white adipose tissue showed activation of ERK1/2, p38, MEK, and JNK during torpor. Importantly, both adipose tissues possess specialized functions that are critical for torpor, with brown adipose required for non-shivering thermogenesis and white adipose utilized as the primary source of lipid fuel for torpor. Overall, these data indicate crucial roles of MAPKs in the regulation of primate organs during torpor.
基金supported by the Project Developing Key Scientific Instrument and Equipment of China(No.2011YQ120023)
文摘The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100kHz (interval by 20kHz) and 10-50W (interval by 10W), respectively. The experimental clata indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.