The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstru...The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstructure,fracture surfaces,and crack growth paths were analyzed before and after CHT.Results indicate that in the stable crack growth region,the growth rates for the as-deposited and cyclic heat-treated specimens follow the relationships da/dN=1.8651×10^(−8)(ΔK)^(3.2271)and da/dN=1.4112×10^(−8)(ΔK)^(3.1125),respectively.Compared with that at the as-deposited state,the microstructure after CHT is transformed from a uniform basket-weave microstructure to a dual-phase microstructure consisting of near-sphericalαandβ-transformed matrix phases.The cyclic process also disrupts the continuity of the grain boundaryα(αGB)at the primaryβ-phase grain boundary.The coarsening of primaryαand the disruption ofαGB continuity are the primary factors to release stress concentration and promote crack deflection,thereby decreasing the fatigue crack growth rate.Additionally,the increased occurrence of crack branching,secondary cracking,and crack bridging in cyclic heat-treated specimens further reduces the crack driving force and slows the fatigue crack growth rate.展开更多
The karst forest in southwestern China is characterized by thin soil layers,numerous fissures and holes,resulting in low soil water availability and poor water retention,making it challenging for plant growth and surv...The karst forest in southwestern China is characterized by thin soil layers,numerous fissures and holes,resulting in low soil water availability and poor water retention,making it challenging for plant growth and survival.While the relationship between plant functional traits and tree growth performance has been extensively studied,the links between tree seasonal growth and drought-tolerant traits in tree species with different leaf habit remains poorly understood.This study evaluated the associations between four-year averaged rainy season stem diameter growth rate and 17 branch and leaf traits across evergreen and deciduous species in a tropical karst forest in southwest China.The cross-species variations in tree growth rates were related to plant hydraulic traits(e.g.,vessel lumen diameter,xylem vessel density,stomatal density,and stomatal size)and leaf anatomical traits(e.g.,total leaf thickness,lower/upper epidermis thickness,and spongy thickness).The growth of evergreen trees exhibited lower hydraulic efficiency but greater drought tolerance than deciduous tree,which enabled them to maintain higher persistence under low soil water availability and consequently a relatively longer growing season.In contrast,deciduous species showed no correlation between their functional traits and growth rate.The distinct water use strategies of evergreen and deciduous trees may offer a potential explanation for their co-existence in the tropical karst forests.展开更多
For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial...For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.展开更多
South Florida’s natural forest ecosystems,including pine rocklands and hardwood hammocks,are threatened by land use change and urbanization,invasive species,and climate change.It is critical to understand the respons...South Florida’s natural forest ecosystems,including pine rocklands and hardwood hammocks,are threatened by land use change and urbanization,invasive species,and climate change.It is critical to understand the responses of these ecosystems to anthropogenic disturbances to conserve the remnants of the USA natural subtropical forests.Using dendrochronology,long-term growth patterns were characterized in three dominant native tree species:Bursera simaruba,Swietenia mahagoni,and Pinus elliottii.Core samples were collected from>30 individuals of each species in hardwood hammocks(B.simaruba and S.mahagoni)and pine rocklands(P.elliottii)to examine growth patterns.Relationships between annual tree growth rates and climatic variables were assessed to address three questions:(1)What are the climatic drivers of growth in these three South Florida tree species?(2)Are their growth rates stable or changing through time?and(3)Are tree growth rates affected by urbanization?Standardized growth rates of the three species have changed through time,with small young trees showing accelerated growth through time,whereas larger,older trees showed declining growth rates.S.mahagoni and B.simaruba grew faster in urbanized parks than in more natural parks,whereas P.elliottii grew slower in urban parks.There were positive correlations between tree growth and the current year’s fall precipitation and no discernable effects of the current year’s monthly temperatures on growth rates of any of the species.These results suggest that the foundational tree species of the southern USA endangered pine rocklands and hardwood hammocks may be vulnerable to ongoing changes in precipitation and temperature as well as other environmental effects associated with urbanization.展开更多
BACKGROUND Premature infant formula is based on milk and contains energy,vitamins,etc.Breast milk is rich in minerals,such as phosphorus and calcium,and proteins.Both can be used for nutritional support in preterm inf...BACKGROUND Premature infant formula is based on milk and contains energy,vitamins,etc.Breast milk is rich in minerals,such as phosphorus and calcium,and proteins.Both can be used for nutritional support in preterm infants with low-birth-weight.However,their effects on the difference in infant growth rate and postpartum depression are still unclear.AIM To explore the effect of early micro-breastfeeding on the growth rate of preterm infants with low-birth-weight and maternal postpartum depression.METHODS Data of 68 preterm infants with low-birth-weight and their mothers admitted to the Department of Neonatology,Suzhou Ninth Hospital Affiliated to Soochow University,between January 2022 and December 2024,were retrospectively collected.The infants were divided into two groups according to the different enteral feeding methods in the early stage:Control group(n=32 cases,premature infant formula feeding)and observation group(n=36 cases,micro-breastfeeding,i.e.,exclusive breastfeeding,no mixed feeding).The baseline data;feeding status;gastrointestinal adverse reactions such as vomiting,gastric retention,and abdominal distension;growth rate(body weight,body length,and head circumference);and adverse events(infection,cholestasis,hyperbilirubinemia,and necrotizing enterocolitis)were compared between the two groups.Moreover,the maternal postpartum depression status of the two groups based of infants based on the Edinburgh postpartum depression scale(EPDS)was compared.RESULTS No significant difference in baseline data was found between the two groups(P>0.05).The onset time of weight gain(6.49±0.53 days vs 7.09±0.61 days,P<0.001),time for complete meconium excretion(6.28±0.92 days vs 8.31±1.17 days,P<0.001),time for recovery to birth weight(8.81±1.40 days vs 10.95±1.64 days,P<0.001),and time to reach full enteral feeding(12.29±2.08 days vs 15.48±2.27 days,P<0.001)were compared between the observation and control groups.The incidence of vomiting,abdominal distension,and gastric retention was significantly lower in the observation group than in the control group,and the difference was significant(P<0.05).The rates of the weight growth(15.88±1.57 g/day vs 14.84±1.51 g/day,P=0.007),head circumference(0.63±0.08 cm/week vs 0.59±0.05 cm/week,P=0.018),and length(0.80±0.12 cm/week vs 0.73±0.14 cm/week,P=0.029)were compared between the observation and control groups.On hospital admission of preterm infants with low-birthweight,the mothers of the two groups did not show a significant difference in the EPDS scores for postpartum depression(P>0.05).Preterm infants with low-birth-weight were hospitalized for 2 weeks,and the EPDS score for maternal postpartum depression was significantly lower in the observation group than in the control group(8.38±1.47 vs 9.49±2.35,P=0.021).CONCLUSION Compared with preterm infant formula feeding,early micro-breastfeeding can more effectively promote the growth rate of preterm infants with low-birth-weight and reduce the gastrointestinal feeding intolerance and related complications,thereby alleviating mothers’concerns about their children and reducing the risk of postpartum depression.展开更多
Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb （mole fraction, %） alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of t...Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb （mole fraction, %） alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of the alloy were investigated. The results show that with the increase of the growth rate and the decrease of the diameter, the fullyβphase solidification changes to the peritectic solidification, and the final microstructure is composed of theα2/γlamellar structure and a multiphase microstructure （B2 phase,α2/γlamellar structure） respectively, which can be attributed to the solute enrichment resulting from the decreasing diffusion and convection ability. The occurrence of peritectic reaction at high growth rate promotes the solute segregation heavily and the coarse lamellar spacing in Al-and Nb-rich region, which greatly decreases the hardness values and leads to the discontinuity of the hardness curves with the increase of the growth rate. Comparatively, the Ti-46Al-8Nb alloy has lower hardness values than the other applied TiAl-based alloys in previous studies.展开更多
This paper examines the effect of supply-side structural reforms on China＇s potential economic growth rate in the coming decade according to the data the authors have gathered. Under the rapid growth scenario with th...This paper examines the effect of supply-side structural reforms on China＇s potential economic growth rate in the coming decade according to the data the authors have gathered. Under the rapid growth scenario with the implementation of supply-side structural reforms, China＇s potential economic growth rate will reach an average of 6.5% and 5.8% respectively in the 13th Five-year Plan （2016-2020） and 14th Five-year Plan （2021-2025） periods. These rates are 0.2 and 0.3 percentage points higher, respectively, than that under the baseline scenario with the inertia of historic trends. In implementing supply-side structural reforms, China must transform governmental functions, break monopolies, create a comprehensive competitive market environment, foster the creation of pro-innovation mechanisms, refocus on quality and efficiency, and raise capital utilization and labor productivity.展开更多
Different from other methodologies for the forecasting of China＇s economic growth rate, this paper forecast of future potential growth rates from the end of China＇s demographic dividends, and then identified it as a...Different from other methodologies for the forecasting of China＇s economic growth rate, this paper forecast of future potential growth rates from the end of China＇s demographic dividends, and then identified it as a growth target. Official promulgation of non-binding targets will guide social expectation, assist in government policy-making, boost confidence in consumers, and provide guidance for producers and investors. Based on our estimation results, we suggest that during the 13th Five-Year Plan period, a GDP growth target between 6. 5% and 7% would be appropriate.展开更多
One of the main obstacles to the development of aquaculture in Senegal is the availability of fry and juveniles in sufficient quantities. The objective of our study is to evaluate the effects of treatment with the hor...One of the main obstacles to the development of aquaculture in Senegal is the availability of fry and juveniles in sufficient quantities. The objective of our study is to evaluate the effects of treatment with the hormone 17 alpha methyl testosterone (17-&-MT) and different doses of Nauclea latifolia root powder on the masculinization rates of tilapia Oreochromis niloticus larvae in Senegal. A total of 450 larvae of Oreochromis niloticus, with an average size of 0.012 g, were placed in 15 aquariums, each containing 30 individuals and fed one of the 5 diets in triplicate. These individuals were fed either a diet containing a plant extract at a dose of 180 mg (T180), 200 mg (T200) and 250 mg (T250) per kg of food, or a diet containing 60 mg/kg of the hormone 17-&-MT (TMT), or a diet without either the plant extract or the hormone (T0). Individuals were fed for 30 days with the treatment diets, and then with the industrial feed for the rest of the experiment. At the end of the study, the results of the masculinization rate were: 80.49%, 73.13%, 69.23%, 66.67% and 45.95% for T250;T200, TMT, T180 and T0 respectively. In summary, we can say that the 250 mg/kg dose provides better masculinization, followed by 200mg/kg and then 17 α MT. For the plant, the increase in the percentage of males is dose-dependent. These results also translate into better growth of individuals in this order. However, the relatively lower survival rates observed in batches treated with Nauclea latifolia extract indicate that these treatments could have a deleterious effect on the survival of Oreochromis niloticus larvae. These results suggest the use of N. latifolia extract at a dose of 250 mg/kg feed for better production of male O. niloticus larvae without compromising their growth.展开更多
Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity f...Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-ΔK relations, the confidence-based da/dN-ΔK relations, and the probabilistic- and confidence-based da/dN-ΔK relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible.展开更多
Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-e...Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-entropy materials,a novel high-entropy(HE)rare-earth zirconate solid solution(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 was designed and successfully synthesized in this work.The as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 is phase-pure with homogeneous rare-earth element distribution.The thermal conductivity of as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 at room temperature is as low as 0.76 W m^-1 K^-1.Moreover,after being heated at 1500℃for 1-18 h,the average grain size of(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 only increases from 1.69μm to 3.92μm,while the average grain size of La2Zr2O7 increases from 1.96μm to 8.89μm.Low thermal conductivity and sluggish grain growth rate indicate that high-entropy(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance.展开更多
Total dissolved gas supersaturation(TDGS) appears when the pressures of gases in a solution exceed the barometric pressures.TDGS is often caused by flood discharge at dams.It may lead to gas bubble disease(GBD) for fi...Total dissolved gas supersaturation(TDGS) appears when the pressures of gases in a solution exceed the barometric pressures.TDGS is often caused by flood discharge at dams.It may lead to gas bubble disease(GBD) for fish and biochemical responses of selected fish and other aquatic organisms.The purpose of this study was to determine the impact of long-term TDGS levels on the growth and biochemical responses of rock carp(Procypris rabaudi Tchang) dwelling in the upper reaches of the Yangtze River.Three-year-old rock carp were exposed to TDGS levels at 100%,104%,108%,112%,and 116% for 42 d.Samples were taken every 7 d after the start of the trial in order to determine catalase(CAT) and superoxide dismutase(SOD) activities in gill and muscle tissues.Samples were taken at Days 0 and 42 of exposure to determine growth rate.Little effect was found on growth rate in all treatment groups.SOD and CAT activities varied in different tissues,according to time of exposure and TDGS levels.The biochemical response of fish exposed to TDGS was more obvious in gill tissue than in muscle tissue.Surveys of SOD and CAT activities in different tissues offer important information about the effect of TDGS on the rare fish in the Yangtze River,and may help evaluate the risk to the aquatic eco-environment and aquatic ecosystem in the downstream of the Yangtze River.展开更多
The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were obse...The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were observed and the growth rates of bainite plates nucleating at grain boundaries, within grains and on preformed bainite were measured. It is indicated that the lengthening rates of bainite plates during the cooling and isothermal processes were different, and that the growth rates of bainite plates nucleating at different types of sites also demon- strated diversity. The bainite plates initiating at [vain boundaries during cooling grew the fastest, while the plates nucleating on preformed bainite did the slowest. However, the growth rate of the bainite plates nucleating at grain boundaries during isothermal transformation de- creased the most, whereas the bainite plates initiating within grains grew the fastest. In addition, the growth rate of ferrite bainite in the study supported the diffusion transformation mechanism of bainite from the viewooint of ~rowth rate.展开更多
The effects of precipitates on the fatigue crack growth rate of AA 7055 Al alloy subjected to different ageing treatments were investigated using transmission electron microscope and fatigue crack growth testing.The r...The effects of precipitates on the fatigue crack growth rate of AA 7055 Al alloy subjected to different ageing treatments were investigated using transmission electron microscope and fatigue crack growth testing.The results show that the T77 treated samples exhibit the lowest crack growth rate,while the crack growth rate of over-aged samples is the highest.In terms of the model based on the reversibility of dislocation motion within the plastic zone close to the crack tip,the improved crack growth resistance is attributed to many precipitates that are coherent with Al matrix in the under-aged and T77 treated samples.When the precipitate is coherent with the Al matrix,the larger the precipitate is,the slower the fatigue crack grows.The effects of grain boundary precipitates and precipitate free zone on the fatigue crack growth resistance are less significant than those of precipitates within grains of the alloy.展开更多
AZ91D magnesium alloys were processed by micro-arc oxidation(MAO)in silicate-containing electrolyte.The key factor of this research is a unique experimental design to fabricate coatings with the same thickness but by ...AZ91D magnesium alloys were processed by micro-arc oxidation(MAO)in silicate-containing electrolyte.The key factor of this research is a unique experimental design to fabricate coatings with the same thickness but by different power voltages which represents different growth rate.The coatings with the same thickness correspond to different coating growth rates of 1,5,15 and 25μm/min,which makes the comparison and analysis-targeted microstructure and corrosion resistance of the coatings academic and practical.The coating growth rate demonstrates considerable influence on surface porosity,size and amount of micro-pores,mass and mass to thickness ratio,and anti-corrosion property of the coatings based on both qualitative and quantitative analysis,but it is not the case for the composition and element distribution of the coatings.An industrial application-oriented selection of appropriate coating growth rate,which demands for both productive efficiency and good performance,has to be considered together with anti-corrosion property of the coatings.The case of the coating fabricated with the growth rate of 15μm/min supports this point strongly.展开更多
Experimental study is performed on the probabilistic models for the long fatigue crack growth rates （da/dN） of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity...Experimental study is performed on the probabilistic models for the long fatigue crack growth rates （da/dN） of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-△K relations, the confidence-based da/dN-△K relations, and the probabilistic- and confidence-based da/dN-△K relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible.展开更多
An Al-5.3%Zn-5.3%Mg alloy was unidirectionally solidified to determine morphological transition and solute distribution by a modification of the Bridgman technique for crystal growth with growth rates ranging from 4-5...An Al-5.3%Zn-5.3%Mg alloy was unidirectionally solidified to determine morphological transition and solute distribution by a modification of the Bridgman technique for crystal growth with growth rates ranging from 4-500 μm/s and a temperature gradient of 25 K/cm. It was determined that growth rates from 6.5-9.5 μm/s generated a cell morphology, where the lower limit corresponds to the plane front to cellular transition and the upper limit indicates the cellular to columnar dendrite transition. The microstructures of the alloys solidified from 30 μm/s to growth rates less than 500 μm/s were mainly composed of columnar dendrites, while the microstructures solidified at growth rates greater than 500 μm/s were equiaxed. Regarding experimental results on solute distribution, a prediction of the model developed by Rappaz and Boettinger for dendrite solidification of multicomponent alloys was applied with excellent agreement. Results of solute distribution were employed to derive the precipitation fraction of τ-phase needed to increase the electrochemical properties of the alloy to be used as an Al-sacrificial anode.展开更多
Three types of fatigue tests for an annealed carbon steel containing carbon of 0.42%were carried out on smooth specimens and specimens with a small blind hole in order to investigate the fatigue crack growth law.A sim...Three types of fatigue tests for an annealed carbon steel containing carbon of 0.42%were carried out on smooth specimens and specimens with a small blind hole in order to investigate the fatigue crack growth law.A simple predicting method for crack growth rates has been proposed involving strengthσband the relation between cyclic stress and strain.The validity of proposed method has been confirmed by experiments on several carbon steels with different loadings.展开更多
The elementary task is to calculate the growth rates of disturbances when the e;method in transition prediction is performed. However, there is no unified knowledge to determine the growth rates of disturbances in thr...The elementary task is to calculate the growth rates of disturbances when the e;method in transition prediction is performed. However, there is no unified knowledge to determine the growth rates of disturbances in three-dimensional（3 D） flows. In this paper, we study the relation among the wave parameters of the disturbance in boundary layers in which the imaginary parts of wave parameters are far smaller than the real parts.The generalized growth rate（GGR） in the direction of group velocity is introduced, and the conservation relation of GGR is strictly deduced in theory. This conservation relation manifests that the GGR only depends on the real parts of wave parameters instead of the imaginary parts. Numerical validations for GGR conservation are also provided in the cases of first/second modes and crossflow modes. The application of GGR to the eN method in 3 D flows is discussed, and the puzzle of determining growth rates in 3 D flows is clarified. A convenient method is also proposed to calculate growth rates of disturbances in 3 D flows. Good agreement between this convenient method and existing methods is found except the condition that the angle between the group velocity direction and the x-direction is close to 90?which can be easily avoided in practical application.展开更多
-Marine chroococcoid phycoerythrin - containing Synechococcus spp. recently have been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although the importance of Synechococcus as ...-Marine chroococcoid phycoerythrin - containing Synechococcus spp. recently have been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although the importance of Synechococcus as food sources for heterotrophic nanoplankton are now recognized, the information about its cycling of biomass and diel patterns is limited and the methodology used varies according to different authors. A selective metabolic inhibitor method was used to allow simultanous estimation of both growth rates and grazing disappearance rates of Synechococcus. Results obtained in the English Channel show growth rates ranging from 0. 25 to 0. 72 d-1 with an average value of 0. 51 d -1and grazing disappearance rates ranged from 0. 21 to 0. 64 d-1 (mean = 0. 44 d-1). Offshore in the Celtic Sea of the Northeast Atlantic Ocean, both rates were lower than in the channel. The similarity between average growth and grazing rates suggests a rapid recycling of Synechococcus biomass. In diel pattern, Synechococcus grazing mortality rates were higher during the day (mean = 0. 61 d-1) than during the night (mean = 0. 21d-1) in all the experiments. A positive correlation was observed between growth rates and in situ temperature ranged from 9 to 20 ℃. Sire-fractionated experiments demonstrate that up to about 7 0 % of Synechococcus disappearance could be attributed to the grazer smaller than 2 μm in diameter. The variations of Synechococcus cell characteristics such as size and phycoerythin contents in the growth and grazing experiments were determined with a flow cytometer. The methodology recently used on estimating dynamics of Synechococcus population is reviewed.展开更多
基金National Key Research and Development Program of China(2024YFB4610803)。
文摘The fatigue crack growth rate of a novel Ti-6Al-4V-1Mo titanium alloy,which is developed for laser directed energy deposition technique,was investigated before and after cyclic heat treatment(CHT).Changes in microstructure,fracture surfaces,and crack growth paths were analyzed before and after CHT.Results indicate that in the stable crack growth region,the growth rates for the as-deposited and cyclic heat-treated specimens follow the relationships da/dN=1.8651×10^(−8)(ΔK)^(3.2271)and da/dN=1.4112×10^(−8)(ΔK)^(3.1125),respectively.Compared with that at the as-deposited state,the microstructure after CHT is transformed from a uniform basket-weave microstructure to a dual-phase microstructure consisting of near-sphericalαandβ-transformed matrix phases.The cyclic process also disrupts the continuity of the grain boundaryα(αGB)at the primaryβ-phase grain boundary.The coarsening of primaryαand the disruption ofαGB continuity are the primary factors to release stress concentration and promote crack deflection,thereby decreasing the fatigue crack growth rate.Additionally,the increased occurrence of crack branching,secondary cracking,and crack bridging in cyclic heat-treated specimens further reduces the crack driving force and slows the fatigue crack growth rate.
基金financially funded by the National Natural Science Foundation of China(3186113307,31770533,31870591)the West Light Talent Program of the Chinese Academy of Sciences(xbzg-zdsys-202218).
文摘The karst forest in southwestern China is characterized by thin soil layers,numerous fissures and holes,resulting in low soil water availability and poor water retention,making it challenging for plant growth and survival.While the relationship between plant functional traits and tree growth performance has been extensively studied,the links between tree seasonal growth and drought-tolerant traits in tree species with different leaf habit remains poorly understood.This study evaluated the associations between four-year averaged rainy season stem diameter growth rate and 17 branch and leaf traits across evergreen and deciduous species in a tropical karst forest in southwest China.The cross-species variations in tree growth rates were related to plant hydraulic traits(e.g.,vessel lumen diameter,xylem vessel density,stomatal density,and stomatal size)and leaf anatomical traits(e.g.,total leaf thickness,lower/upper epidermis thickness,and spongy thickness).The growth of evergreen trees exhibited lower hydraulic efficiency but greater drought tolerance than deciduous tree,which enabled them to maintain higher persistence under low soil water availability and consequently a relatively longer growing season.In contrast,deciduous species showed no correlation between their functional traits and growth rate.The distinct water use strategies of evergreen and deciduous trees may offer a potential explanation for their co-existence in the tropical karst forests.
基金Supported by Projects from Chongqing Municipal Science and Technology Commission(CSTB2022NSCQ-MSX0445)。
文摘For the Sylvester continued fraction expansions of real numbers,FAN et al.(2007)proved that,for almost all real numbers,the nth partial quotient grows exponentially with respect to the product of the first n-1 partial quotients.In this paper,we establish the Hausdorff dimension of the exceptional set where the growth rate is a general function.
基金supported by the Kushlan Fund from the University of Miami Department of Biology.
文摘South Florida’s natural forest ecosystems,including pine rocklands and hardwood hammocks,are threatened by land use change and urbanization,invasive species,and climate change.It is critical to understand the responses of these ecosystems to anthropogenic disturbances to conserve the remnants of the USA natural subtropical forests.Using dendrochronology,long-term growth patterns were characterized in three dominant native tree species:Bursera simaruba,Swietenia mahagoni,and Pinus elliottii.Core samples were collected from>30 individuals of each species in hardwood hammocks(B.simaruba and S.mahagoni)and pine rocklands(P.elliottii)to examine growth patterns.Relationships between annual tree growth rates and climatic variables were assessed to address three questions:(1)What are the climatic drivers of growth in these three South Florida tree species?(2)Are their growth rates stable or changing through time?and(3)Are tree growth rates affected by urbanization?Standardized growth rates of the three species have changed through time,with small young trees showing accelerated growth through time,whereas larger,older trees showed declining growth rates.S.mahagoni and B.simaruba grew faster in urbanized parks than in more natural parks,whereas P.elliottii grew slower in urban parks.There were positive correlations between tree growth and the current year’s fall precipitation and no discernable effects of the current year’s monthly temperatures on growth rates of any of the species.These results suggest that the foundational tree species of the southern USA endangered pine rocklands and hardwood hammocks may be vulnerable to ongoing changes in precipitation and temperature as well as other environmental effects associated with urbanization.
文摘BACKGROUND Premature infant formula is based on milk and contains energy,vitamins,etc.Breast milk is rich in minerals,such as phosphorus and calcium,and proteins.Both can be used for nutritional support in preterm infants with low-birth-weight.However,their effects on the difference in infant growth rate and postpartum depression are still unclear.AIM To explore the effect of early micro-breastfeeding on the growth rate of preterm infants with low-birth-weight and maternal postpartum depression.METHODS Data of 68 preterm infants with low-birth-weight and their mothers admitted to the Department of Neonatology,Suzhou Ninth Hospital Affiliated to Soochow University,between January 2022 and December 2024,were retrospectively collected.The infants were divided into two groups according to the different enteral feeding methods in the early stage:Control group(n=32 cases,premature infant formula feeding)and observation group(n=36 cases,micro-breastfeeding,i.e.,exclusive breastfeeding,no mixed feeding).The baseline data;feeding status;gastrointestinal adverse reactions such as vomiting,gastric retention,and abdominal distension;growth rate(body weight,body length,and head circumference);and adverse events(infection,cholestasis,hyperbilirubinemia,and necrotizing enterocolitis)were compared between the two groups.Moreover,the maternal postpartum depression status of the two groups based of infants based on the Edinburgh postpartum depression scale(EPDS)was compared.RESULTS No significant difference in baseline data was found between the two groups(P>0.05).The onset time of weight gain(6.49±0.53 days vs 7.09±0.61 days,P<0.001),time for complete meconium excretion(6.28±0.92 days vs 8.31±1.17 days,P<0.001),time for recovery to birth weight(8.81±1.40 days vs 10.95±1.64 days,P<0.001),and time to reach full enteral feeding(12.29±2.08 days vs 15.48±2.27 days,P<0.001)were compared between the observation and control groups.The incidence of vomiting,abdominal distension,and gastric retention was significantly lower in the observation group than in the control group,and the difference was significant(P<0.05).The rates of the weight growth(15.88±1.57 g/day vs 14.84±1.51 g/day,P=0.007),head circumference(0.63±0.08 cm/week vs 0.59±0.05 cm/week,P=0.018),and length(0.80±0.12 cm/week vs 0.73±0.14 cm/week,P=0.029)were compared between the observation and control groups.On hospital admission of preterm infants with low-birthweight,the mothers of the two groups did not show a significant difference in the EPDS scores for postpartum depression(P>0.05).Preterm infants with low-birth-weight were hospitalized for 2 weeks,and the EPDS score for maternal postpartum depression was significantly lower in the observation group than in the control group(8.38±1.47 vs 9.49±2.35,P=0.021).CONCLUSION Compared with preterm infant formula feeding,early micro-breastfeeding can more effectively promote the growth rate of preterm infants with low-birth-weight and reduce the gastrointestinal feeding intolerance and related complications,thereby alleviating mothers’concerns about their children and reducing the risk of postpartum depression.
基金Projects(51071062,51274077,51271068)supported by the National Natural Science Foundation of ChinaProject(2011-P03)supported by Open Fund of State Key Laboratory of Mold and Die Technology of Huazhong University of Science and Technology+1 种基金Project(HIT.NSRIF.2013002)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2011CB605504)supported by the National Basic Research Program of China
文摘Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb （mole fraction, %） alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of the alloy were investigated. The results show that with the increase of the growth rate and the decrease of the diameter, the fullyβphase solidification changes to the peritectic solidification, and the final microstructure is composed of theα2/γlamellar structure and a multiphase microstructure （B2 phase,α2/γlamellar structure） respectively, which can be attributed to the solute enrichment resulting from the decreasing diffusion and convection ability. The occurrence of peritectic reaction at high growth rate promotes the solute segregation heavily and the coarse lamellar spacing in Al-and Nb-rich region, which greatly decreases the hardness values and leads to the discontinuity of the hardness curves with the increase of the growth rate. Comparatively, the Ti-46Al-8Nb alloy has lower hardness values than the other applied TiAl-based alloys in previous studies.
文摘This paper examines the effect of supply-side structural reforms on China＇s potential economic growth rate in the coming decade according to the data the authors have gathered. Under the rapid growth scenario with the implementation of supply-side structural reforms, China＇s potential economic growth rate will reach an average of 6.5% and 5.8% respectively in the 13th Five-year Plan （2016-2020） and 14th Five-year Plan （2021-2025） periods. These rates are 0.2 and 0.3 percentage points higher, respectively, than that under the baseline scenario with the inertia of historic trends. In implementing supply-side structural reforms, China must transform governmental functions, break monopolies, create a comprehensive competitive market environment, foster the creation of pro-innovation mechanisms, refocus on quality and efficiency, and raise capital utilization and labor productivity.
文摘Different from other methodologies for the forecasting of China＇s economic growth rate, this paper forecast of future potential growth rates from the end of China＇s demographic dividends, and then identified it as a growth target. Official promulgation of non-binding targets will guide social expectation, assist in government policy-making, boost confidence in consumers, and provide guidance for producers and investors. Based on our estimation results, we suggest that during the 13th Five-Year Plan period, a GDP growth target between 6. 5% and 7% would be appropriate.
文摘One of the main obstacles to the development of aquaculture in Senegal is the availability of fry and juveniles in sufficient quantities. The objective of our study is to evaluate the effects of treatment with the hormone 17 alpha methyl testosterone (17-&-MT) and different doses of Nauclea latifolia root powder on the masculinization rates of tilapia Oreochromis niloticus larvae in Senegal. A total of 450 larvae of Oreochromis niloticus, with an average size of 0.012 g, were placed in 15 aquariums, each containing 30 individuals and fed one of the 5 diets in triplicate. These individuals were fed either a diet containing a plant extract at a dose of 180 mg (T180), 200 mg (T200) and 250 mg (T250) per kg of food, or a diet containing 60 mg/kg of the hormone 17-&-MT (TMT), or a diet without either the plant extract or the hormone (T0). Individuals were fed for 30 days with the treatment diets, and then with the industrial feed for the rest of the experiment. At the end of the study, the results of the masculinization rate were: 80.49%, 73.13%, 69.23%, 66.67% and 45.95% for T250;T200, TMT, T180 and T0 respectively. In summary, we can say that the 250 mg/kg dose provides better masculinization, followed by 200mg/kg and then 17 α MT. For the plant, the increase in the percentage of males is dose-dependent. These results also translate into better growth of individuals in this order. However, the relatively lower survival rates observed in batches treated with Nauclea latifolia extract indicate that these treatments could have a deleterious effect on the survival of Oreochromis niloticus larvae. These results suggest the use of N. latifolia extract at a dose of 250 mg/kg feed for better production of male O. niloticus larvae without compromising their growth.
基金Project supported by the National Natural Science Foundation of China (Nos.50375130and50323003), the Special Foundation of National Excellent Ph.D.Thesis (No.200234) and thePlanned Itemforthe Outstanding Young Teachers ofMinistry ofEducationofChina (No.2101)
文摘Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-ΔK relations, the confidence-based da/dN-ΔK relations, and the probabilistic- and confidence-based da/dN-ΔK relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible.
基金financially supported by the National Natural Science Foundation of China (Nos.51672064 and U1435206)
文摘Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-entropy materials,a novel high-entropy(HE)rare-earth zirconate solid solution(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 was designed and successfully synthesized in this work.The as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 is phase-pure with homogeneous rare-earth element distribution.The thermal conductivity of as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 at room temperature is as low as 0.76 W m^-1 K^-1.Moreover,after being heated at 1500℃for 1-18 h,the average grain size of(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 only increases from 1.69μm to 3.92μm,while the average grain size of La2Zr2O7 increases from 1.96μm to 8.89μm.Low thermal conductivity and sluggish grain growth rate indicate that high-entropy(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance.
基金Project (No. 50979063) supported by the National Natural Science Foundation of China
文摘Total dissolved gas supersaturation(TDGS) appears when the pressures of gases in a solution exceed the barometric pressures.TDGS is often caused by flood discharge at dams.It may lead to gas bubble disease(GBD) for fish and biochemical responses of selected fish and other aquatic organisms.The purpose of this study was to determine the impact of long-term TDGS levels on the growth and biochemical responses of rock carp(Procypris rabaudi Tchang) dwelling in the upper reaches of the Yangtze River.Three-year-old rock carp were exposed to TDGS levels at 100%,104%,108%,112%,and 116% for 42 d.Samples were taken every 7 d after the start of the trial in order to determine catalase(CAT) and superoxide dismutase(SOD) activities in gill and muscle tissues.Samples were taken at Days 0 and 42 of exposure to determine growth rate.Little effect was found on growth rate in all treatment groups.SOD and CAT activities varied in different tissues,according to time of exposure and TDGS levels.The biochemical response of fish exposed to TDGS was more obvious in gill tissue than in muscle tissue.Surveys of SOD and CAT activities in different tissues offer important information about the effect of TDGS on the rare fish in the Yangtze River,and may help evaluate the risk to the aquatic eco-environment and aquatic ecosystem in the downstream of the Yangtze River.
基金financially supported by the National Natural Science Foundation of China(No.51274154)the National High-Tech Research and Development Program of China(No.2012AA03A504)+1 种基金the State Key Laboratory of Development and Application Technology of Automotive Steels(Baosteel Group)the Key Project of Hubei Education Committee,China(No.20121101)
文摘The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were observed and the growth rates of bainite plates nucleating at grain boundaries, within grains and on preformed bainite were measured. It is indicated that the lengthening rates of bainite plates during the cooling and isothermal processes were different, and that the growth rates of bainite plates nucleating at different types of sites also demon- strated diversity. The bainite plates initiating at [vain boundaries during cooling grew the fastest, while the plates nucleating on preformed bainite did the slowest. However, the growth rate of the bainite plates nucleating at grain boundaries during isothermal transformation de- creased the most, whereas the bainite plates initiating within grains grew the fastest. In addition, the growth rate of ferrite bainite in the study supported the diffusion transformation mechanism of bainite from the viewooint of ~rowth rate.
基金Project(2005CB623700) supported by the National Basic Research Program of China
文摘The effects of precipitates on the fatigue crack growth rate of AA 7055 Al alloy subjected to different ageing treatments were investigated using transmission electron microscope and fatigue crack growth testing.The results show that the T77 treated samples exhibit the lowest crack growth rate,while the crack growth rate of over-aged samples is the highest.In terms of the model based on the reversibility of dislocation motion within the plastic zone close to the crack tip,the improved crack growth resistance is attributed to many precipitates that are coherent with Al matrix in the under-aged and T77 treated samples.When the precipitate is coherent with the Al matrix,the larger the precipitate is,the slower the fatigue crack grows.The effects of grain boundary precipitates and precipitate free zone on the fatigue crack growth resistance are less significant than those of precipitates within grains of the alloy.
基金The Creative Research Group Fund Grant of Gansu Province(1111RJDA011)
文摘AZ91D magnesium alloys were processed by micro-arc oxidation(MAO)in silicate-containing electrolyte.The key factor of this research is a unique experimental design to fabricate coatings with the same thickness but by different power voltages which represents different growth rate.The coatings with the same thickness correspond to different coating growth rates of 1,5,15 and 25μm/min,which makes the comparison and analysis-targeted microstructure and corrosion resistance of the coatings academic and practical.The coating growth rate demonstrates considerable influence on surface porosity,size and amount of micro-pores,mass and mass to thickness ratio,and anti-corrosion property of the coatings based on both qualitative and quantitative analysis,but it is not the case for the composition and element distribution of the coatings.An industrial application-oriented selection of appropriate coating growth rate,which demands for both productive efficiency and good performance,has to be considered together with anti-corrosion property of the coatings.The case of the coating fabricated with the growth rate of 15μm/min supports this point strongly.
基金国家自然科学基金，Special Foundation of National Excellent Ph.D.Thesis，Outstanding Young Teachers of Ministry of Education of China
文摘Experimental study is performed on the probabilistic models for the long fatigue crack growth rates （da/dN） of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN-△K relations, the confidence-based da/dN-△K relations, and the probabilistic- and confidence-based da/dN-△K relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible.
基金the financial support from Consejo Nacional de Ciencia y Tecnología (CONACYT) Project N° 129780PAPIIT-UNAM project N° IN213912-3
文摘An Al-5.3%Zn-5.3%Mg alloy was unidirectionally solidified to determine morphological transition and solute distribution by a modification of the Bridgman technique for crystal growth with growth rates ranging from 4-500 μm/s and a temperature gradient of 25 K/cm. It was determined that growth rates from 6.5-9.5 μm/s generated a cell morphology, where the lower limit corresponds to the plane front to cellular transition and the upper limit indicates the cellular to columnar dendrite transition. The microstructures of the alloys solidified from 30 μm/s to growth rates less than 500 μm/s were mainly composed of columnar dendrites, while the microstructures solidified at growth rates greater than 500 μm/s were equiaxed. Regarding experimental results on solute distribution, a prediction of the model developed by Rappaz and Boettinger for dendrite solidification of multicomponent alloys was applied with excellent agreement. Results of solute distribution were employed to derive the precipitation fraction of τ-phase needed to increase the electrochemical properties of the alloy to be used as an Al-sacrificial anode.
基金the supports from the Research Foundation for Visiting Scholars of Key Laboratory of Solid Mechanics and FML of Education Ministry,P R Chinathe supports from Japan Society for Promotion of Science
文摘Three types of fatigue tests for an annealed carbon steel containing carbon of 0.42%were carried out on smooth specimens and specimens with a small blind hole in order to investigate the fatigue crack growth law.A simple predicting method for crack growth rates has been proposed involving strengthσband the relation between cyclic stress and strain.The validity of proposed method has been confirmed by experiments on several carbon steels with different loadings.
基金Project supported by the National Natural Science Foundation of China(Nos.11672351 and11332007)the National Key R&D Plan(No.2016YFA0401200)the FengLei Youth Innovation Fund of China Aerodynamics Research and Development Center(No.KT-FLJJ-201803)
文摘The elementary task is to calculate the growth rates of disturbances when the e;method in transition prediction is performed. However, there is no unified knowledge to determine the growth rates of disturbances in three-dimensional（3 D） flows. In this paper, we study the relation among the wave parameters of the disturbance in boundary layers in which the imaginary parts of wave parameters are far smaller than the real parts.The generalized growth rate（GGR） in the direction of group velocity is introduced, and the conservation relation of GGR is strictly deduced in theory. This conservation relation manifests that the GGR only depends on the real parts of wave parameters instead of the imaginary parts. Numerical validations for GGR conservation are also provided in the cases of first/second modes and crossflow modes. The application of GGR to the eN method in 3 D flows is discussed, and the puzzle of determining growth rates in 3 D flows is clarified. A convenient method is also proposed to calculate growth rates of disturbances in 3 D flows. Good agreement between this convenient method and existing methods is found except the condition that the angle between the group velocity direction and the x-direction is close to 90?which can be easily avoided in practical application.
文摘-Marine chroococcoid phycoerythrin - containing Synechococcus spp. recently have been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although the importance of Synechococcus as food sources for heterotrophic nanoplankton are now recognized, the information about its cycling of biomass and diel patterns is limited and the methodology used varies according to different authors. A selective metabolic inhibitor method was used to allow simultanous estimation of both growth rates and grazing disappearance rates of Synechococcus. Results obtained in the English Channel show growth rates ranging from 0. 25 to 0. 72 d-1 with an average value of 0. 51 d -1and grazing disappearance rates ranged from 0. 21 to 0. 64 d-1 (mean = 0. 44 d-1). Offshore in the Celtic Sea of the Northeast Atlantic Ocean, both rates were lower than in the channel. The similarity between average growth and grazing rates suggests a rapid recycling of Synechococcus biomass. In diel pattern, Synechococcus grazing mortality rates were higher during the day (mean = 0. 61 d-1) than during the night (mean = 0. 21d-1) in all the experiments. A positive correlation was observed between growth rates and in situ temperature ranged from 9 to 20 ℃. Sire-fractionated experiments demonstrate that up to about 7 0 % of Synechococcus disappearance could be attributed to the grazer smaller than 2 μm in diameter. The variations of Synechococcus cell characteristics such as size and phycoerythin contents in the growth and grazing experiments were determined with a flow cytometer. The methodology recently used on estimating dynamics of Synechococcus population is reviewed.
