Adverse childhood experiences(ACEs)can negatively affect mental health,whereas character strengths seem to be positively correlated with mental health.Detailed information on the history of ACEs among university stude...Adverse childhood experiences(ACEs)can negatively affect mental health,whereas character strengths seem to be positively correlated with mental health.Detailed information on the history of ACEs among university students in China and the extent which mental health is associated with ACEs and character strengths can contribute to the needed empirical evidence for relevant stakeholders.Objectives of this study are 1)to estimate the prevalence of ACEs among undergraduate students in Southern China;and 2)to assess the extent which mental health outcomes(positive growth,well-being,and depression)are associated with ACEs and character strengths among undergraduate students in Southern China.We conducted a self-administered survey amongfirst and second-year students at a university in Southern China and analyzed data using descriptive statistics and linear regression analyses.Among the 779 students who completed the questionnaire,283 were males,439 were females,and 57 did not indicate their gender.The prevalence of ACEs among the participants was 32.1%.History of ACEs was associated with lower positive growth score(Adjusted Beta=-0.20;95%CI=-0.37,-0.02;p=0.030)and lower well-being score(Adjusted Beta=-1.13;95%CI=-2.04,-0.23;p=0.014).Vitality domain of character strength was associated with all three mental health outcomes after adjusting for covariables(all p-values<0.001).Our studyfindings provide empirical evidence for stakeholders in university mental health.However,caveats regarding lack of temporality,selection bias,social desirability bias,and lack of generalizability should be considered in the interpretation of the studyfindings.展开更多
This study aimed to examine the effect of L-ornithine hydrochloride ingestion on serum growth hormone secretion response after strength training in young men who did not regularly engage in high intensity exercise. Te...This study aimed to examine the effect of L-ornithine hydrochloride ingestion on serum growth hormone secretion response after strength training in young men who did not regularly engage in high intensity exercise. Ten healthy young males without workout habits (age: 22.2 +/- 1.0 yr). Subjects performed biceps curl strength training after L-ornithine hydro- chloride and placebo ingestions. They participated in both of the above conditions randomly with a week interval in between. Serum growth hormone and ornithine levels were measured before L-ornithine hydrochloride or placebo ingestions and at 30 minutes after strength training. Serum growth hormone and ornithine level were measured. A change magnitude of serum growth hormone was significantly larger in the L-ornithine hydrochloride condition than in the placebo condition, and the effect size was also large (t = 1.91, p = .044, ES = .75). A significant interaction (F = 280.98, p = 0.000, ηp2 = 0.96) was found in serum ornithine and a multiple comparison test showed that it was greater in the L-ornithine hydrochloride condition. Serum growth hormone level after strength training increases by L-ornithine hydrochloride ingestion in untrained young males.展开更多
Forest structure and function are subject to risks of growth declines from intensified drought and frequent extreme events related to climate warming.Knowledge of tree growth declines will help anticipate future respo...Forest structure and function are subject to risks of growth declines from intensified drought and frequent extreme events related to climate warming.Knowledge of tree growth declines will help anticipate future responses of forests to climate change.In this study,we investigated tree growth declines over the last four centuries in a juniper forest on the eastern Tibetan Plateau.By analyzing the radial growth trajectories of individual trees,we identified two events of intense growth decline,one in 1817–1830 and the other in 1969–1999 over the past four centuries.The intensity of the recent decline was unprecedented in the period under study.Ring-width chronology showed a positive correlation with self-calibrating Palmer Drought Severity Indices and a negative correlation with mean monthly temperatures in May and June.The recent intensified growth decline may have been due to temperatureinduced frequent droughts in the study area.Our findings suggest that trees in this juniper forest may face a higher risk of growth decline and even mortality under continued climate warming.展开更多
The Ti-Al-Sn-Zr-Cr-Mo-V-Si (Ti-62A) alloy, an alpha-beta alloy with high strength and fracture toughness, is currently used as an advanced structural material in aerospace and non-aerospace applications. Thermo-mech...The Ti-Al-Sn-Zr-Cr-Mo-V-Si (Ti-62A) alloy, an alpha-beta alloy with high strength and fracture toughness, is currently used as an advanced structural material in aerospace and non-aerospace applications. Thermo-mechanical processes can be used to optimize the relationship between its strength and fracture toughness. A Ti-62A alloy bar can be machined through a transus β-forged plus α+β solution treated and aged specimen with a lamellar alpha microstructure. The effects of heat treatment on the mechanical properties were discussed. Heat treatment provided a practical balance of strength, fracture toughness, and fatigue crack growth resistance. A comparison of the Ti-62A alloy with the Ti-62222S alloy under the same thermo-mechanical processing conditions showed that their properties are at the same level.展开更多
Objective To investigate the clinical symptoms experienced by patients with thoracic spinal tumors and verify the associated symptoms that are predictive of a decline in muscle strength in the lower limbs.Methods A si...Objective To investigate the clinical symptoms experienced by patients with thoracic spinal tumors and verify the associated symptoms that are predictive of a decline in muscle strength in the lower limbs.Methods A single-center,retrospective cross-sectional study was conducted on in-patients diagnosed with epidural thoracic spinal tumors between January 2011 and May 2021.The study involved a review of electronic medical records and radiographs and the collection of clinical data.The differences in clinical manifestations between patients with constipation and those without constipation were analyzed.Binary logistic regression analyses were performed to identify risk factors associated with a decline in muscle strength in the lower limbs.Results A total of 227 patients were enrolled,including 131 patients with constipation and 96 without constipation.The constipation group had a significantly higher proportion of patients who experienced difficulty walking or paralysis compared to those without constipation prior to surgery(83.2%vs.17.7%,χ~2=99.035,P 0.001).Constipation(OR=9.522,95%CI:4.150±21.849,P 0.001)and urinary retention(OR=14.490,95%CI:4.543±46.213,P 0.001)were independent risk factors for muscle strength decline in the lower limbs.Conclusions The study observed that patients with thoracic spinal tumors who experienced constipation symptoms had a higher incidence of lower limb weakness.Moreover,the analysis revealed that constipation and urinary retention were independent risk factors associated with a preoperative decline in muscle strength of lower limbs.展开更多
The austenite grain growth behavior of Q1030 steel was studied under different heating conditions. The austenite grain size increases with the heating temperature and holding time increasing. Austenite grains grow in ...The austenite grain growth behavior of Q1030 steel was studied under different heating conditions. The austenite grain size increases with the heating temperature and holding time increasing. Austenite grains grow in an exponential manner with rising heating tem- perature and in a parabolic manner with prolonging holding time. A mathematical model for describing the austenite grain growth behavior of Q 1030 steel was obtained on the basis of experimental results using regression analysis. When the heating temperatures lie between 1000 and 1100℃ at a certain holding time, abnormal grain growth appears, which causes mixed grains in Q1030 steel.展开更多
The strength,fracture toughness and fatigue crack growth resistance of 7050-T7451 aluminum alloy plate with different thicknesses(35 mm and 160 mm) were investigated by means of optical microscope,scanning electron mi...The strength,fracture toughness and fatigue crack growth resistance of 7050-T7451 aluminum alloy plate with different thicknesses(35 mm and 160 mm) were investigated by means of optical microscope,scanning electron microscope and transmission electron microscope.The results show that thicker plate has lower strength and fracture toughness but higher fatigue crack growth resistance,by comparison to the thinner plate.The drop of strength is mainly attributed to grain coarsening in the thicker plate,and the increased degree of recrystallization results in the loss of KIC.However,the coarsened grains in the thicker plate make cracks deflected and closure effect enhanced due to surface roughness increased.For both of plates,in the fracture surface subjected plain strain,a transition from transgranular dimpled fracture to intergranular dimpled fracture is observed during the fracture process.展开更多
AIM: To evaluate properties of bone quantity/quality using young non-obese Type 1(T1D)-diabetic(NOD) prone and syngenic non-diabetic(NOD.scid) mice.METHODS: Quantitative bone assessment of tibia was conducted using du...AIM: To evaluate properties of bone quantity/quality using young non-obese Type 1(T1D)-diabetic(NOD) prone and syngenic non-diabetic(NOD.scid) mice.METHODS: Quantitative bone assessment of tibia was conducted using dual-energy X-ray absorptiometry(DXA) for the evaluation of body mass,bone mineral content,body fat mass and lean mass.Qualitative assessment was accomplished by three-point breakage for assessment of force to failure and micro-computed tomography for evaluation of trabecular and cortical properties of bone.In addition,fasting blood was evaluated prior to sacrifice at week eleven and fifteen to evaluate and compare glucose homeostasis between the strains of mice.RESULTS: Our findings support a perturbation in the relationship between bone quantity,quality,and subsequently,the association between structure and strength.There were no differences in DXA-assessed body composition(body fat,% fat mass and lean mass) and bone composition(bone mineral content and bone mineral density) between strains.However,relative to NOD.scid,NOD mice had lower trabecular bone volume,relative trabecular bone volume,trabecular number and trabecular total material density(P < 0.05).Conversely,NOD mice had greater cortical total mean volume(P < 0.05).General linear models analysis adjusted for body weight revealed a significant contribution of T1D to bone health as early as 5 wk.CONCLUSION: It is well-established that diabetes is a significant risk factor for increased fractures,although the underlying mechanisms are not fully understood.Investigation of bone parameters encompassing strength and structure early in the life course will facilitate the elucidation of the pathogenesis of impaired bone integrity.展开更多
In order to establish the immune procedure for Actinobacillus pleuropneumonia and to determine the date for the first immunization on piglets, the growth and decline law of A. pleuropneumonia material antibodies in th...In order to establish the immune procedure for Actinobacillus pleuropneumonia and to determine the date for the first immunization on piglets, the growth and decline law of A. pleuropneumonia material antibodies in the piglets borne by cows inoculated with A. pleuropneumonia vaccines (type I, II, and VII) before delivery was detected. The results showed that type I, II, and VII maternal antibodies in piglets decreased gradually with the age growing overall, and was at the critical protection value at the ages of 42-50 days (type I) and 28 days (type VII), lower than the quantification rate; and the antibodies all turned to be negative until the ages of 70 days (type I), 60 days (type VII) and 35 days (type II). The first immunization should be carried out at the age of 42-50 days using type I A. pleuropneumonia vaccine, and at the age of 28 days using type VII A. pleuropneumonia vaccine. However, type II A. pleuropneumonia maternal antibody had lower level and positive rate and could not well protect piglets, so the various A. pleuropneumonia vaccines differed in the date for the first immunization. In order to achieve a better immunization effect, A. pleuropneumonia vaccines with different valences should be further researched and developed.展开更多
Low-dimensional quantum spin systems with the Cu2+ central ion are still in the focus of experimental and theoretical research. Here is reported on growth of mm-sized single-crystals of the low-dimensional S = 1/2 spi...Low-dimensional quantum spin systems with the Cu2+ central ion are still in the focus of experimental and theoretical research. Here is reported on growth of mm-sized single-crystals of the low-dimensional S = 1/2 spin compound Cu6(Ge,Si)6O18·6H2O by a diffusion technique in aqueous solution. A route to form Si-rich crystals down to possible dioptase, the pure silicate, is discussed. Motivated by previously reported incorrect assignments of UV-VIS spectra, the assignment of dd excitations from such spectra of the hexahydrate and the fully dehydrated compound is proposed in comparison to dioptase and selected Cu(II) oxo-compounds using bond strength considerations. Non-doped cuprates as layer compounds show higher excitation energies than the title compound. However, when the antiferromagnetic interaction energy as Jz·ln(2) is taken into account for cuprates, a single linear relationship between the Dqe excitation energy and equatorial Cu(II)-O bond strength is confirmed for all compounds. A linear representation is also confirmed between 2A1g energies and a function of axial and equatorial Cu-O bond distances if auxiliary axial bonds are used for four-coordinated compounds. The quotient Dt/Ds of experimental orbital energies deviating from the general trend to smaller values indicates the existence of H2O respectively Cl−axial ligands in comparison to oxo-ligands, whereas larger Dt/Dqe values indicate missing axial bonds. The quotient of the excitation energy 2A1g by 2·2Eg-2B2g allows checking for correctness of the assignment and to distinguish between axial oxo-ligands and others like H2O or Cl−.展开更多
The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% de...The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the annealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.展开更多
The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates ...The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates to create diferent conditions for maize growth.We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology,moisture content,mechanical strength and dry matter,and the relationship between stalk breaking force and these indicators during the silking stage(R1),milk stage(R3),physiological maturity stage(R6),and 20 days after R6.Plant height at R1 positively affected stalk breaking force.At R3,the cofficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance.At R6,the key indicators were the coefficient of the center of gravity height and plant fresh weight.After R6,the key indicator was the coefficient of the center of gravity height.The crushing strength of the fourth internode correlated significanty and positively with the stalk breaking force from R1 to R6,which indicates that crushing strength is a reliable indicator of stalk mechanical strength.These results suggest that high stalk strength and low ear height beneft lodging resistance prior to R6.During and after R6,the cofficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.展开更多
This paper deals with the effects of codoped VC/Cr3C2 and sintering temperature on the magnetic and mechanical properties of ultra-fine grained WC-12%Co alloys. Results show that the synergistic action of doped VC/Cr3...This paper deals with the effects of codoped VC/Cr3C2 and sintering temperature on the magnetic and mechanical properties of ultra-fine grained WC-12%Co alloys. Results show that the synergistic action of doped VC/Cr3C2 in optimal proportion enhances both the hardness and transverse rupture strength (TRS) of the alloys, with more homogeneous microstructtLre. When the alloy is sintered at 1430℃ and with 0.5% Cr3C2/0.2% VC, the TRS reaches 3786 MPa, the hardness is 91.7 HRA and the grain size smaller than 0.6 μm. The numerical analyses on grain growth during the sintering process show that both VC precipitating on the WC grain boundary and Cr3C2 dissolving in the Co phase decrease the solid/liquid interfacial energy γ, the process of dissolution and reprecipitation is greatly retarded and the coarsening of WC grains is inhibited.展开更多
In this work,the crack growth behaviours of high strength low alloy(HSLA)steel E690 with three crystallographic orientations(the rolling direction,normal direction,and transverse direction)were investigated and compar...In this work,the crack growth behaviours of high strength low alloy(HSLA)steel E690 with three crystallographic orientations(the rolling direction,normal direction,and transverse direction)were investigated and compared from the view of the mechano-electrochemical ef-fect at the crack tip.The results show that the crack growth of the HSLA steel is controlled by the corrosion fracture at the crack tip.The vari-ation of crystallographic orientation in E690 steel plate has no influence on the crack tip electrochemical reaction and crack growth mechanism,but changes the crack growth rate.When the stress loading direction is parallel to the rolling direction and the fracture layer is parallel to the transverse-normal plane,the crack growth rate is the slowest with a value of 0.0185 mm·h^(-1).When the load direction and the fracture layer are parallel to the normal direction and the rolling-transverse plane,respectively,the crack growth rate is the highest with a value of 0.0309 mm·h^(-1).This phenomenon is ascribed to the different microstructural and mechanical properties in the rolling direction,normal direction,and transverse direction of E690 steel plate.展开更多
Welding of high strength low alloy steels (HSLA) involves usage of low, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the avail...Welding of high strength low alloy steels (HSLA) involves usage of low, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the availability of the filler material. In the present investigation, the fatigue crack growth behaviour of weld metal (WM) and heat affected zone (HAZ) regions of under matched (UM), equal matched (EM) and over matched (OM) joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) process has been used to fabricate the butt joints. Centre cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behaviour of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0).A method has been proposed to predict the fatigue life of HSLA steel welds using fracture mechanics approach by incorporating influences of mismatch ratio (MMR) and notch location.展开更多
In this paper, ultrasonic (20 kHz) fatigue tests were performed on specimens of a high-strength steel in very high cycle fatigue (VHCF) regime. Experimental results showed that for most tested specimens failed in ...In this paper, ultrasonic (20 kHz) fatigue tests were performed on specimens of a high-strength steel in very high cycle fatigue (VHCF) regime. Experimental results showed that for most tested specimens failed in a VHCF regime, a fatigue crack originated from the interior of specimen with a fish-eye pattern, which contained a fine granular area (FGA) centered by an inclusion as the crack origin. Then, a two-parameter model is proposed to predict the fatigue life of high-strength steels with fish-eye mode failure in a VHCF regime, which takes into account the inclusion size and the FGA size. The model was verified by the data of present experiments and those in the literature. Furthermore, an analytic formula was obtained for estimating the equivalent crack growth rate within the FGA. The results also indicated that the stress intensity factor range at the front of the FGA varies within a small range, which is irrespective of stress amplitude and fatigue life.展开更多
Trace rare earth elements were used in order to strengthen the Sn60 Pb40 solder alloy. The experimental results show that the high temperature tensile strength of near eutectic Sn60 Pb40 solder alloy is increased b...Trace rare earth elements were used in order to strengthen the Sn60 Pb40 solder alloy. The experimental results show that the high temperature tensile strength of near eutectic Sn60 Pb40 solder alloy is increased by about 70% after adding trace rare earth elements. Analysis shows that the high affinity between rare earth element and Sn leads to the variation of contact angle at the three phase junction of S/L interface during eutectic growth and further changes the Pb concentration at the S/L interface needed for coupled eutectic growth. Thus the eutectic microstructure can directly grow upon the primary Pb rich phase and the formation of coarse Sn rich halo is suppressed. Therefore homogeneous metallurgical microstructure can be obtained.展开更多
Disease suppression of Fusarium crown rot and the changes in free amino acid contents in mycorrhizal asparagus (Asparagus officinalis L., cv. “Welcome”) plants were investigated. Sixteen weeks after arbuscular mycor...Disease suppression of Fusarium crown rot and the changes in free amino acid contents in mycorrhizal asparagus (Asparagus officinalis L., cv. “Welcome”) plants were investigated. Sixteen weeks after arbuscular mycorrhizal fungus (AMF;Glomus intraradices) inoculation, mycorrhizal plants showed higher dry weight of shoots than non-mycorrhizal plants, and AMF colonization level in a root system reached up to 73.3%. Ten weeks after Fusarium proliferatum (Fp;N1-31, SUF1207) inoculation, control plants showed 100% incidence and high severity in the 2 Fp isolates. However, AMF plants showed lower severity than non-AMF plants in the 2 Fp isolates. Ten weeks after Fp (N1-31) inoculation, the increase in 7 constituents of amino acids (glutamine, arginine, aspartic acid, alanine, citrulline, GABA, glycine) in shoots, and 9 in roots (asparagine, arginine, threonine, serine, glutamine, citrulline, valine, GABA, histidine) occurred in AMF plants. From these findings, plant growth promotion and suppression of Fusarium crown rot occurred in mycorrhizal asparagus plants, and the disease tolerance was supposed to be associated with the symbiosis-specific increase in free amino acids.展开更多
Potassium (K) deficiency affects cotton growth and development and fiber properties. An experiment was conducted in an outdoor pot culture facility by imposing four potassium stress treatments (100%, 40%, 20% and 0% o...Potassium (K) deficiency affects cotton growth and development and fiber properties. An experiment was conducted in an outdoor pot culture facility by imposing four potassium stress treatments (100%, 40%, 20% and 0% of optimum K level) prior to flowering during 2010 and 2011 growing season. Upland cotton cultivar, TM-1, was seeded in the pots comprised of fine sand as rooting medium. Flowers and bolls were tagged daily to estimate boll maturation period (BMP). Leaf samples were collected every four days from flowering to maturity to estimate leaf K content. Plant height and node numbers were recorded from emergence to 21 days after treatment. Photosynthesis and stomatal conductance were measured weekly from day of treatment imposition to physiological maturity at an interval of seven days. Stem, leaf, and boll dry-component weights, and boll numbers were recorded at the end of the experiment in each year. From each boll, the lint samples were collected and grouped based on average leaf potassium concentration during BMP, and fiber quality parameters were recorded for each group in each treatment. At high K deficient (0 K) condition, total biomass declined by 27% and 28% in years 2010 and 2011, respectively. Significantly, lower numbers of bolls were retained per plant at 0 K stress treatment during both the years. Leaf photosynthesis (r2 = 0.92) and stomatal conductance (r2 = 0.80) declined with declining leaf K levels. Fiber length, strength, micronaire, and uniformity declined linearly with decrease in leaf K content. Weaker fibers with medium length were produced under K-deficient conditions with micronaire values in the discount range. Fiber uniformity, however, did not decline with decrease in leaf K. The identified leaf K status-specific relationships for fiber properties could be used to improve management practices under potassium deficiency and to develop new sub-routines of the existing cotton simulation models. New and improved models will be useful not only in management, but also in arena of policy decisions including future climate change impact assessment analysis.展开更多
基金funded by the Guangdong Provincial Philosophy and Social Science Planning Project(GD22XJY25).
文摘Adverse childhood experiences(ACEs)can negatively affect mental health,whereas character strengths seem to be positively correlated with mental health.Detailed information on the history of ACEs among university students in China and the extent which mental health is associated with ACEs and character strengths can contribute to the needed empirical evidence for relevant stakeholders.Objectives of this study are 1)to estimate the prevalence of ACEs among undergraduate students in Southern China;and 2)to assess the extent which mental health outcomes(positive growth,well-being,and depression)are associated with ACEs and character strengths among undergraduate students in Southern China.We conducted a self-administered survey amongfirst and second-year students at a university in Southern China and analyzed data using descriptive statistics and linear regression analyses.Among the 779 students who completed the questionnaire,283 were males,439 were females,and 57 did not indicate their gender.The prevalence of ACEs among the participants was 32.1%.History of ACEs was associated with lower positive growth score(Adjusted Beta=-0.20;95%CI=-0.37,-0.02;p=0.030)and lower well-being score(Adjusted Beta=-1.13;95%CI=-2.04,-0.23;p=0.014).Vitality domain of character strength was associated with all three mental health outcomes after adjusting for covariables(all p-values<0.001).Our studyfindings provide empirical evidence for stakeholders in university mental health.However,caveats regarding lack of temporality,selection bias,social desirability bias,and lack of generalizability should be considered in the interpretation of the studyfindings.
文摘This study aimed to examine the effect of L-ornithine hydrochloride ingestion on serum growth hormone secretion response after strength training in young men who did not regularly engage in high intensity exercise. Ten healthy young males without workout habits (age: 22.2 +/- 1.0 yr). Subjects performed biceps curl strength training after L-ornithine hydro- chloride and placebo ingestions. They participated in both of the above conditions randomly with a week interval in between. Serum growth hormone and ornithine levels were measured before L-ornithine hydrochloride or placebo ingestions and at 30 minutes after strength training. Serum growth hormone and ornithine level were measured. A change magnitude of serum growth hormone was significantly larger in the L-ornithine hydrochloride condition than in the placebo condition, and the effect size was also large (t = 1.91, p = .044, ES = .75). A significant interaction (F = 280.98, p = 0.000, ηp2 = 0.96) was found in serum ornithine and a multiple comparison test showed that it was greater in the L-ornithine hydrochloride condition. Serum growth hormone level after strength training increases by L-ornithine hydrochloride ingestion in untrained young males.
基金financially supported by the National Natural Science Foundation of China project(No.31330015)
文摘Forest structure and function are subject to risks of growth declines from intensified drought and frequent extreme events related to climate warming.Knowledge of tree growth declines will help anticipate future responses of forests to climate change.In this study,we investigated tree growth declines over the last four centuries in a juniper forest on the eastern Tibetan Plateau.By analyzing the radial growth trajectories of individual trees,we identified two events of intense growth decline,one in 1817–1830 and the other in 1969–1999 over the past four centuries.The intensity of the recent decline was unprecedented in the period under study.Ring-width chronology showed a positive correlation with self-calibrating Palmer Drought Severity Indices and a negative correlation with mean monthly temperatures in May and June.The recent intensified growth decline may have been due to temperatureinduced frequent droughts in the study area.Our findings suggest that trees in this juniper forest may face a higher risk of growth decline and even mortality under continued climate warming.
文摘The Ti-Al-Sn-Zr-Cr-Mo-V-Si (Ti-62A) alloy, an alpha-beta alloy with high strength and fracture toughness, is currently used as an advanced structural material in aerospace and non-aerospace applications. Thermo-mechanical processes can be used to optimize the relationship between its strength and fracture toughness. A Ti-62A alloy bar can be machined through a transus β-forged plus α+β solution treated and aged specimen with a lamellar alpha microstructure. The effects of heat treatment on the mechanical properties were discussed. Heat treatment provided a practical balance of strength, fracture toughness, and fatigue crack growth resistance. A comparison of the Ti-62A alloy with the Ti-62222S alloy under the same thermo-mechanical processing conditions showed that their properties are at the same level.
文摘Objective To investigate the clinical symptoms experienced by patients with thoracic spinal tumors and verify the associated symptoms that are predictive of a decline in muscle strength in the lower limbs.Methods A single-center,retrospective cross-sectional study was conducted on in-patients diagnosed with epidural thoracic spinal tumors between January 2011 and May 2021.The study involved a review of electronic medical records and radiographs and the collection of clinical data.The differences in clinical manifestations between patients with constipation and those without constipation were analyzed.Binary logistic regression analyses were performed to identify risk factors associated with a decline in muscle strength in the lower limbs.Results A total of 227 patients were enrolled,including 131 patients with constipation and 96 without constipation.The constipation group had a significantly higher proportion of patients who experienced difficulty walking or paralysis compared to those without constipation prior to surgery(83.2%vs.17.7%,χ~2=99.035,P 0.001).Constipation(OR=9.522,95%CI:4.150±21.849,P 0.001)and urinary retention(OR=14.490,95%CI:4.543±46.213,P 0.001)were independent risk factors for muscle strength decline in the lower limbs.Conclusions The study observed that patients with thoracic spinal tumors who experienced constipation symptoms had a higher incidence of lower limb weakness.Moreover,the analysis revealed that constipation and urinary retention were independent risk factors associated with a preoperative decline in muscle strength of lower limbs.
文摘The austenite grain growth behavior of Q1030 steel was studied under different heating conditions. The austenite grain size increases with the heating temperature and holding time increasing. Austenite grains grow in an exponential manner with rising heating tem- perature and in a parabolic manner with prolonging holding time. A mathematical model for describing the austenite grain growth behavior of Q 1030 steel was obtained on the basis of experimental results using regression analysis. When the heating temperatures lie between 1000 and 1100℃ at a certain holding time, abnormal grain growth appears, which causes mixed grains in Q1030 steel.
基金Project(2012CB619503)supported by State Key Fundamental Research Program of China
文摘The strength,fracture toughness and fatigue crack growth resistance of 7050-T7451 aluminum alloy plate with different thicknesses(35 mm and 160 mm) were investigated by means of optical microscope,scanning electron microscope and transmission electron microscope.The results show that thicker plate has lower strength and fracture toughness but higher fatigue crack growth resistance,by comparison to the thinner plate.The drop of strength is mainly attributed to grain coarsening in the thicker plate,and the increased degree of recrystallization results in the loss of KIC.However,the coarsened grains in the thicker plate make cracks deflected and closure effect enhanced due to surface roughness increased.For both of plates,in the fracture surface subjected plain strain,a transition from transgranular dimpled fracture to intergranular dimpled fracture is observed during the fracture process.
基金Supported by R00DK083333(KC)T32DK007545(LJH)P60DK079626 UAB Diabetes Research Center Pilot/Feasibility Grant
文摘AIM: To evaluate properties of bone quantity/quality using young non-obese Type 1(T1D)-diabetic(NOD) prone and syngenic non-diabetic(NOD.scid) mice.METHODS: Quantitative bone assessment of tibia was conducted using dual-energy X-ray absorptiometry(DXA) for the evaluation of body mass,bone mineral content,body fat mass and lean mass.Qualitative assessment was accomplished by three-point breakage for assessment of force to failure and micro-computed tomography for evaluation of trabecular and cortical properties of bone.In addition,fasting blood was evaluated prior to sacrifice at week eleven and fifteen to evaluate and compare glucose homeostasis between the strains of mice.RESULTS: Our findings support a perturbation in the relationship between bone quantity,quality,and subsequently,the association between structure and strength.There were no differences in DXA-assessed body composition(body fat,% fat mass and lean mass) and bone composition(bone mineral content and bone mineral density) between strains.However,relative to NOD.scid,NOD mice had lower trabecular bone volume,relative trabecular bone volume,trabecular number and trabecular total material density(P < 0.05).Conversely,NOD mice had greater cortical total mean volume(P < 0.05).General linear models analysis adjusted for body weight revealed a significant contribution of T1D to bone health as early as 5 wk.CONCLUSION: It is well-established that diabetes is a significant risk factor for increased fractures,although the underlying mechanisms are not fully understood.Investigation of bone parameters encompassing strength and structure early in the life course will facilitate the elucidation of the pathogenesis of impaired bone integrity.
基金Supported by National Natural Science Foundation of China(31560696)Development Fund for Scientific Research Institutes in Hainan Province(KYYS-2014-32)Special Fund for Integration of Production,Learning and Research of Hainan Province(cxy20150008)
文摘In order to establish the immune procedure for Actinobacillus pleuropneumonia and to determine the date for the first immunization on piglets, the growth and decline law of A. pleuropneumonia material antibodies in the piglets borne by cows inoculated with A. pleuropneumonia vaccines (type I, II, and VII) before delivery was detected. The results showed that type I, II, and VII maternal antibodies in piglets decreased gradually with the age growing overall, and was at the critical protection value at the ages of 42-50 days (type I) and 28 days (type VII), lower than the quantification rate; and the antibodies all turned to be negative until the ages of 70 days (type I), 60 days (type VII) and 35 days (type II). The first immunization should be carried out at the age of 42-50 days using type I A. pleuropneumonia vaccine, and at the age of 28 days using type VII A. pleuropneumonia vaccine. However, type II A. pleuropneumonia maternal antibody had lower level and positive rate and could not well protect piglets, so the various A. pleuropneumonia vaccines differed in the date for the first immunization. In order to achieve a better immunization effect, A. pleuropneumonia vaccines with different valences should be further researched and developed.
文摘Low-dimensional quantum spin systems with the Cu2+ central ion are still in the focus of experimental and theoretical research. Here is reported on growth of mm-sized single-crystals of the low-dimensional S = 1/2 spin compound Cu6(Ge,Si)6O18·6H2O by a diffusion technique in aqueous solution. A route to form Si-rich crystals down to possible dioptase, the pure silicate, is discussed. Motivated by previously reported incorrect assignments of UV-VIS spectra, the assignment of dd excitations from such spectra of the hexahydrate and the fully dehydrated compound is proposed in comparison to dioptase and selected Cu(II) oxo-compounds using bond strength considerations. Non-doped cuprates as layer compounds show higher excitation energies than the title compound. However, when the antiferromagnetic interaction energy as Jz·ln(2) is taken into account for cuprates, a single linear relationship between the Dqe excitation energy and equatorial Cu(II)-O bond strength is confirmed for all compounds. A linear representation is also confirmed between 2A1g energies and a function of axial and equatorial Cu-O bond distances if auxiliary axial bonds are used for four-coordinated compounds. The quotient Dt/Ds of experimental orbital energies deviating from the general trend to smaller values indicates the existence of H2O respectively Cl−axial ligands in comparison to oxo-ligands, whereas larger Dt/Dqe values indicate missing axial bonds. The quotient of the excitation energy 2A1g by 2·2Eg-2B2g allows checking for correctness of the assignment and to distinguish between axial oxo-ligands and others like H2O or Cl−.
文摘The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the annealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.
基金Supported by the National Key Research and Development Program of China(2017YFD0300302)the earmarked fund for China Agriculture Research System(CARS-02-25)+1 种基金the Science and Technology Program of the Sixth Division of Xinjiang Production and Construction Corps in China(1703)the Agricultural Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences.
文摘The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates to create diferent conditions for maize growth.We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology,moisture content,mechanical strength and dry matter,and the relationship between stalk breaking force and these indicators during the silking stage(R1),milk stage(R3),physiological maturity stage(R6),and 20 days after R6.Plant height at R1 positively affected stalk breaking force.At R3,the cofficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance.At R6,the key indicators were the coefficient of the center of gravity height and plant fresh weight.After R6,the key indicator was the coefficient of the center of gravity height.The crushing strength of the fourth internode correlated significanty and positively with the stalk breaking force from R1 to R6,which indicates that crushing strength is a reliable indicator of stalk mechanical strength.These results suggest that high stalk strength and low ear height beneft lodging resistance prior to R6.During and after R6,the cofficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.
基金the National Natural Science Foundation of China (No. 50372043).
文摘This paper deals with the effects of codoped VC/Cr3C2 and sintering temperature on the magnetic and mechanical properties of ultra-fine grained WC-12%Co alloys. Results show that the synergistic action of doped VC/Cr3C2 in optimal proportion enhances both the hardness and transverse rupture strength (TRS) of the alloys, with more homogeneous microstructtLre. When the alloy is sintered at 1430℃ and with 0.5% Cr3C2/0.2% VC, the TRS reaches 3786 MPa, the hardness is 91.7 HRA and the grain size smaller than 0.6 μm. The numerical analyses on grain growth during the sintering process show that both VC precipitating on the WC grain boundary and Cr3C2 dissolving in the Co phase decrease the solid/liquid interfacial energy γ, the process of dissolution and reprecipitation is greatly retarded and the coarsening of WC grains is inhibited.
基金This study was financially supported by the China Postdoctoral Science Foundation(No.2021M693706)Independent research project of State Key Laboratory of Mechanical Transmission of China(No.SKLMT-ZZKT-2021M10)the National Environmental Corrosion Platform of China(No.NECP).
文摘In this work,the crack growth behaviours of high strength low alloy(HSLA)steel E690 with three crystallographic orientations(the rolling direction,normal direction,and transverse direction)were investigated and compared from the view of the mechano-electrochemical ef-fect at the crack tip.The results show that the crack growth of the HSLA steel is controlled by the corrosion fracture at the crack tip.The vari-ation of crystallographic orientation in E690 steel plate has no influence on the crack tip electrochemical reaction and crack growth mechanism,but changes the crack growth rate.When the stress loading direction is parallel to the rolling direction and the fracture layer is parallel to the transverse-normal plane,the crack growth rate is the slowest with a value of 0.0185 mm·h^(-1).When the load direction and the fracture layer are parallel to the normal direction and the rolling-transverse plane,respectively,the crack growth rate is the highest with a value of 0.0309 mm·h^(-1).This phenomenon is ascribed to the different microstructural and mechanical properties in the rolling direction,normal direction,and transverse direction of E690 steel plate.
文摘Welding of high strength low alloy steels (HSLA) involves usage of low, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the availability of the filler material. In the present investigation, the fatigue crack growth behaviour of weld metal (WM) and heat affected zone (HAZ) regions of under matched (UM), equal matched (EM) and over matched (OM) joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) process has been used to fabricate the butt joints. Centre cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behaviour of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0).A method has been proposed to predict the fatigue life of HSLA steel welds using fracture mechanics approach by incorporating influences of mismatch ratio (MMR) and notch location.
基金supported by the National Basic Research Program of China (Grant 2012CB937500)the National Natural Science Foundations of China (Grants 11172304 and 11202210)
文摘In this paper, ultrasonic (20 kHz) fatigue tests were performed on specimens of a high-strength steel in very high cycle fatigue (VHCF) regime. Experimental results showed that for most tested specimens failed in a VHCF regime, a fatigue crack originated from the interior of specimen with a fish-eye pattern, which contained a fine granular area (FGA) centered by an inclusion as the crack origin. Then, a two-parameter model is proposed to predict the fatigue life of high-strength steels with fish-eye mode failure in a VHCF regime, which takes into account the inclusion size and the FGA size. The model was verified by the data of present experiments and those in the literature. Furthermore, an analytic formula was obtained for estimating the equivalent crack growth rate within the FGA. The results also indicated that the stress intensity factor range at the front of the FGA varies within a small range, which is irrespective of stress amplitude and fatigue life.
文摘Trace rare earth elements were used in order to strengthen the Sn60 Pb40 solder alloy. The experimental results show that the high temperature tensile strength of near eutectic Sn60 Pb40 solder alloy is increased by about 70% after adding trace rare earth elements. Analysis shows that the high affinity between rare earth element and Sn leads to the variation of contact angle at the three phase junction of S/L interface during eutectic growth and further changes the Pb concentration at the S/L interface needed for coupled eutectic growth. Thus the eutectic microstructure can directly grow upon the primary Pb rich phase and the formation of coarse Sn rich halo is suppressed. Therefore homogeneous metallurgical microstructure can be obtained.
文摘Disease suppression of Fusarium crown rot and the changes in free amino acid contents in mycorrhizal asparagus (Asparagus officinalis L., cv. “Welcome”) plants were investigated. Sixteen weeks after arbuscular mycorrhizal fungus (AMF;Glomus intraradices) inoculation, mycorrhizal plants showed higher dry weight of shoots than non-mycorrhizal plants, and AMF colonization level in a root system reached up to 73.3%. Ten weeks after Fusarium proliferatum (Fp;N1-31, SUF1207) inoculation, control plants showed 100% incidence and high severity in the 2 Fp isolates. However, AMF plants showed lower severity than non-AMF plants in the 2 Fp isolates. Ten weeks after Fp (N1-31) inoculation, the increase in 7 constituents of amino acids (glutamine, arginine, aspartic acid, alanine, citrulline, GABA, glycine) in shoots, and 9 in roots (asparagine, arginine, threonine, serine, glutamine, citrulline, valine, GABA, histidine) occurred in AMF plants. From these findings, plant growth promotion and suppression of Fusarium crown rot occurred in mycorrhizal asparagus plants, and the disease tolerance was supposed to be associated with the symbiosis-specific increase in free amino acids.
文摘Potassium (K) deficiency affects cotton growth and development and fiber properties. An experiment was conducted in an outdoor pot culture facility by imposing four potassium stress treatments (100%, 40%, 20% and 0% of optimum K level) prior to flowering during 2010 and 2011 growing season. Upland cotton cultivar, TM-1, was seeded in the pots comprised of fine sand as rooting medium. Flowers and bolls were tagged daily to estimate boll maturation period (BMP). Leaf samples were collected every four days from flowering to maturity to estimate leaf K content. Plant height and node numbers were recorded from emergence to 21 days after treatment. Photosynthesis and stomatal conductance were measured weekly from day of treatment imposition to physiological maturity at an interval of seven days. Stem, leaf, and boll dry-component weights, and boll numbers were recorded at the end of the experiment in each year. From each boll, the lint samples were collected and grouped based on average leaf potassium concentration during BMP, and fiber quality parameters were recorded for each group in each treatment. At high K deficient (0 K) condition, total biomass declined by 27% and 28% in years 2010 and 2011, respectively. Significantly, lower numbers of bolls were retained per plant at 0 K stress treatment during both the years. Leaf photosynthesis (r2 = 0.92) and stomatal conductance (r2 = 0.80) declined with declining leaf K levels. Fiber length, strength, micronaire, and uniformity declined linearly with decrease in leaf K content. Weaker fibers with medium length were produced under K-deficient conditions with micronaire values in the discount range. Fiber uniformity, however, did not decline with decrease in leaf K. The identified leaf K status-specific relationships for fiber properties could be used to improve management practices under potassium deficiency and to develop new sub-routines of the existing cotton simulation models. New and improved models will be useful not only in management, but also in arena of policy decisions including future climate change impact assessment analysis.