Background As a unique livestock adapted to the harsh environment,grazing yaks frequently suffer from malnutrition and even death because of the lower yield and quality of forage in the Qinghai-Tibet Plateau during th...Background As a unique livestock adapted to the harsh environment,grazing yaks frequently suffer from malnutrition and even death because of the lower yield and quality of forage in the Qinghai-Tibet Plateau during the cold season.Certain stress conditions,such as environmental changes,disease,and malnutrition,can lead to a decrease in glutamine(Gln)synthesis,which fails to cover the physiological needs of the organism.Supplementation with exogenous Gln can promote nutrient digestion and improve rumen fermentation in ruminant animals under malnutrition.However,whether Gln could alleviate the barrier function injury induced by malnutrition and its mechanism is still unclear.Methods In the in vivo experiments,24 healthy yaks(31 months,265.35±25.81 kg)were randomly divided into 3 groups,namely control group(Con,free access to the basal diet),feed restriction group(FR,50% level of ad libitum feed intake),and feed restriction+Gln group(FR+Gln,50% level of ad libitum feed intake from d 1 to 30,50% level of ad libitum feed intake+1%Gln from d 31 to 60).In the in vitro experiments,the yak rumen epithelial cells(YRECs)were divided into 4 groups:Con group(complete medium),Gln group(complete medium+10 mmol/L Gln),Gln deficiency group(Gln-D,Gln-free medium),and Gln deficiency+Gln group(Gln-D+Gln,Gln-free medium+10 mmol/L Gln).Results In the in vivo experiments,FR significantly decreased the ruminal concentrations of acetate,propionate,butyrate,iso-butyrate,and total volatile fatty acid(VFA)(P<0.05).FR also reduced the m RNA expression of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase,and the concentrations of lactate,histone acetyltransferase(p300),histone deacetylase(HDAC),as well as the histone lysine lactylation level compared to Con group,while Gln supplementation alleviated them(P<0.05).In the in vitro experiments,Gln alleviated the Gln-D-induced down-regulation of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase m RNA expressions and reduction of lactate,p300,HDAC concentrations,and histone lysine lactylation level(P<0.05).Besides,p300 inhibitor abrogated Gln repair of barrier function damage in YRECs(P<0.05).Conclusions Overall,our results revealed the potential mechanism of Gln supplementation to repair malnutritioninduced damage of rumen epithelial barrier function in yaks,which might be related to histone lysine lactylation.However,because we do not have a control group receiving glutamine alone,we cannot determine the impact of Gln on the rumen epithelial function of normal yaks.展开更多
The direct transformation of dinitrogen(N_(2)) into nitrogen-containing organic compounds holds substantial importance.In this work,we report a titanium-promoted method for the conversion of N_(2) to N-methylimides.In...The direct transformation of dinitrogen(N_(2)) into nitrogen-containing organic compounds holds substantial importance.In this work,we report a titanium-promoted method for the conversion of N_(2) to N-methylimides.Initially,the N_(2)-bridging end-on dititanium side-on dipotassium complex[{(Tren^(TMS))Ti}_(2)(μ-η^(1):η^(1):η^(2):η^(2)-N_(2)K_(2))] underwent simultaneous disproportionation and N-methylation reactions in the presence of methyl trifluoromethanesulfonate(Me OTf),yielding [{(N^(Me,TMS)NN^(TMS)_(2))Ti}(μ-NMe)]_(2) with complete cleavage of the N≡N bond.The nucleophilicity of the N-methylated intermediate allowed it to react with electrophilic reagents such as trimethylchlorosilane(TMSCl) to form heptamethyldisilazane,or with acyl chlorides to generate N-methylimides.Moreover,nitrogen-15(^(15)N) labeled experiments provided a novel approach to synthesizing ^(15)N-labeled methylimides.展开更多
OBJECTIVE Oxidative sress is one of the key factor responsible for occurrence and development of hepatic fibrosis,a common consequence of chronic liver injury of multiple etiology.Nuclear factor erythroid 2-related fa...OBJECTIVE Oxidative sress is one of the key factor responsible for occurrence and development of hepatic fibrosis,a common consequence of chronic liver injury of multiple etiology.Nuclear factor erythroid 2-related factor 2(Nrf2)serves as a major regulator of a celular defense system against oxidative stress.Xiaochaihutang(XCHT),a compound of seven botanical extracts used for liver diseases traditionally in East Asia.However,few studies have investigated its anti-hepatic fibrosis effects and pathophysiological mechanism of action.The present study was designed to confirm the anti-hepatic fibrosis effects and explore its potential mechanism of action by investigating the intervention of Nrf2 pathway.METHODS Liver fibrosis was induced by repeated injection of Carbon tetrachloride(CCl4) over a period of 9 weeks.Starting from the 6 th week,the animals in treatment groups were given the appropriate dose of XCHT granules and silybin.Biochemical parameters,histological changes of the liver and alpha-smooth muscle actin(α-SMA) were determined.The expressions of Nrf2,Keap1,Nqo1,HO-1,Gclc and Gclm were assessed by RT-PCR and Western blot.RESULTS CCl4 caused a significant fibrosis damage in the rat liver and the liver functions and fibrosis degree were significantly improved by XCHT(5 g·kg^(-1) and 10 g·kg^(-1)).XCHT(5 g·kg^(-1) and 10 g·kg^(-1)) treatment significantly decreased the number of cells labeled with α-SMA antibodies.Moreover,XCHT(5 g·kg^(-1) and 10 g·kg^(-1))significantly increase Nqo1,HO-1,Gclc and Gclm expressions in the liver.CONCLUSION T hese studies establish XCHT is a potentially useful therapeutic agent for treatment of hepatic fibrosis and it might be via regulation of Nrf2 pathway in rats against oxidative stress,making further efforts to inhibiting the activated HSCs.Activation or up-regulation of Nrf2 pathway may be an alternative treatment strategy for liver fibrosis.展开更多
3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have...3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have been limited. This study explores the impact of poly(vinylidene fluoride) and polydopamine-coated aluminum particles on the thermal and combustion properties of 3D printed hybrid rocket fuels. Physical self-assembly and anti-solvent methods were employed for constructing composite μAl particles. Characterization using SEM, XRD, XPS, FTIR, and μCT revealed a core-shell structure and homogeneous elemental distribution. Thermal analysis showed that PVDF coatings significantly increased the heat of combustion for aluminum particles, with maximum enhancement observed in μAl@PDA@PVDF(denoted as μAl@PF) at 6.20 k J/g. Subsequently, 3D printed fuels with varying pure and composite μAl particle contents were prepared using 3D printing. Combustion tests indicated higher regression rates for Al@PF/Resin composites compared to pure resin, positively correlating with particle content. The fluorocarbon-alumina reaction during the combustion stage intensified Al particle combustion, reducing residue size. A comprehensive model based on experiments provides insights into the combustion process of PDA and PVDF-coated droplets. This study advances the design of 3D-printed hybrid rocket fuels, offering strategies to improve regression rates and energy release, crucial for enhancing solid fuel performance for hybrid propulsion.展开更多
BACKGROUND Effective health management for high-risk stroke populations is essential.The hospital-community-home(HCH)collaborative health management(CHM)model leverages resources from hospitals,communities,and familie...BACKGROUND Effective health management for high-risk stroke populations is essential.The hospital-community-home(HCH)collaborative health management(CHM)model leverages resources from hospitals,communities,and families.By integrating patient information across these three domains,it facilitates the delivery of tailored guidance,health risk assessments,and three-in-one health education.AIM To explore the effects of the HCH-CHM model on stroke risk reduction in highrisk populations.METHODS In total,110 high-risk stroke patients screened in the community from January 2019 to January 2023 were enrolled,with 52 patients in the control group receiving routine health education and 58 in the observation group receiving HCH-CHM model interventions based on routine health education.Stroke awareness scores,health behavior levels,medication adherence,blood pressure,serum biochemical markers(systolic/diastolic blood pressure,total cholesterol,and triglyceride),and psychological measures(self-rating anxiety/depression scale)were evaluated and compared between groups.RESULTS The observation group showed statistically significant improvements in stroke awareness scores and health behavior levels compared to the control group(P<0.05),with notable enhancements in lifestyle and dietary habits(P<0.05)and reductions in postintervention systolic blood pressure,diastolic blood pressure,total cholesterol,triglyceride,self-rating anxiety scale,and self-rating depression scale scores(P<0.05).CONCLUSION The HCH-CHM model had a significant positive effect on high-risk stroke populations,effectively increasing disease awareness,improving health behavior and medication adherence,and appropriately ameliorating blood pressure,serum biochemical marker levels,and negative psychological symptoms.展开更多
This study comprehensively studied the precipitation ofαlaths and formation of inducedγnanotwins in a cast Ti-48Al-3Nb-1.5Ta(at.%)alloy tempered at theα+γphase region.The evolution of the microstruc-ture and its c...This study comprehensively studied the precipitation ofαlaths and formation of inducedγnanotwins in a cast Ti-48Al-3Nb-1.5Ta(at.%)alloy tempered at theα+γphase region.The evolution of the microstruc-ture and its corresponding atomic mechanisms were investigated by transmission electron microscopy.The results show thatαphase precipitates as intersected laths,nucleates at stacking faults,and grows by a diffusion-controlled ledge-kink-terrace mechanism.The precipitation ofαlath introduces high stress concentrations at theγ/αinterface,produces dislocations and stacking faults,and induces the formation ofγnanotwins.Theγnanotwins nucleate at stacking faults emitted from theγ/αinterface and grow by Frank partials climbing,Schockley partials gliding,and several new mechanisms related to non-planar reactions of dislocations and annihilation of antiphase boundaries.Theγnanotwins are limited to sub-microns due to the lack of driving force.High temperatures promote the formation ofγnanotwins by activating non-planar reactions of dislocations and atom diffusion.In addition,Nb and Ta can promoteαlath precipitation andγnanotwin formation by reducing the stacking fault energy and preferring stacking fault emission.In summary,these findings provide new insights intoαlath precipitation andγtwinning mechanisms,which are relevant as theoretical bases for microstructure control and refinement of castγ-TiAl alloys.展开更多
This study investigates the fatigue crack propagation mechanism of a new high-strength and high-tough Ti-Mo-Cr-V-Nb-Al titanium alloy with three types of microstructures(basketweave structure,lamellar structure,and bi...This study investigates the fatigue crack propagation mechanism of a new high-strength and high-tough Ti-Mo-Cr-V-Nb-Al titanium alloy with three types of microstructures(basketweave structure,lamellar structure,and bimodal structure)through fatigue crack propagation rate tests and fatigue threshold value tests.The resistance of the alloy to fatigue crack propagation was found to be closely correlated with the morphology and distribution ofαparticles,as evidenced by microscopic examination of fracture surfaces and analysis of crack propagation paths.The primaryαparticles demonstrated superior resistance to crack propagation compared to the secondaryαparticles.The basketweave structure showed exceptional resistance to fatigue crack propagation at all stages.The lamellar structure mainly resists long crack propagation during rapid propagation,and its threshold value is the lowest,which makes it easy to produce microcrack propagation.On the contrary,the bimodal structure has the highest threshold value among the three,so its resistance to short crack growth is more excellent,but it has the highest crack growth rate in the higher stress intensity factor range.Theαparticles in the three microstructures also undergo rotational motion relative to the force axis during fatigue crack propagation,thereby adjusting the uneven stress distribution betweenα/βphases through slip behavior and further coordinating deformation.展开更多
Gold-platinum(Au-Pt)alloy has aroused considerable attention due to its ultra-low magnetic susceptibility(MS)in testing mass(TM)on spacecraft.However,the effect of Au content on the properties of the alloy has not yet...Gold-platinum(Au-Pt)alloy has aroused considerable attention due to its ultra-low magnetic susceptibility(MS)in testing mass(TM)on spacecraft.However,the effect of Au content on the properties of the alloy has not yet been understood.In this study,the composition design of Au-Pt alloy with ultra-low MS was achieved through density functional theory(DFT)and experimental methods.The elastic,thermal properties and electronic structure were systematically investigated,the composition range was further optimized and Au75Pt25 was determined to be the most suitable alloy for TM material.The phase composition of this alloy after cold rolling and solid solution was characterized,indicating a single-phase FCC structure.In addition,there is a good validation between the experimental Vickers hardness and the DFT results.This work provides new insights into the compositional optimization of Au-Pt alloys and lays the foundation for alloy development.展开更多
In the field of organic synthesis,the core objective of retrosynthetic methods is to deduce possible synthetic routes and precursor molecules for complex target molecules.Traditional retrosynthetic methods,such as tem...In the field of organic synthesis,the core objective of retrosynthetic methods is to deduce possible synthetic routes and precursor molecules for complex target molecules.Traditional retrosynthetic methods,such as template-based retrosynthesis,have high accuracy and interpretability in specific types of reactions but are limited by the scope of the template library,making it difficult to adapt to new or uncommon reaction types.Moreover,sequence-to-sequence retrosynthetic prediction methods,although they enhance the flexibility of prediction,often overlook the complexity of molecular graph structures and the actual interactions between atoms,which limits the accuracy and reliability of the predictions.To address these limitations,this paper proposes a Molecular Retrosynthesis Top-k Prediction based on the Latent Generation Process(MRLGP)that uses latent variables from graph neural networks to model the generation process and produce diverse set of reactants.Utilising an encoding method based on Graphormer,the authors have also introduced topology-aware positional encoding to better capture the interactions between atomic nodes in the molecular graph structure,thereby more accurately simulating the retrosynthetic process.The MRLGP model significantly enhances the accuracy and diversity of predictions by correlating discrete latent variables with the reactant generation process and progressively constructing molecular graphs using a variational autoregressive decoder.Experimental results on benchmark datasets such as USPTO-50k,USPTO-Full,and USPTO-DIVERSE demonstrate that MRLGP outperforms baseline models on multiple Top-k evaluation metrics.Additionally,ablation experiments conducted on the USPTO-50K dataset further validate the effectiveness of the methods used in the encoder and decoder parts of the model.展开更多
The effect of A1 content on the microstructure and solidification characteristics of Ti-A1-Nb-V-Cr alloys in as-cast and isothermally treated states was investigated using X-ray diffraction （XRD）, scanning electron ...The effect of A1 content on the microstructure and solidification characteristics of Ti-A1-Nb-V-Cr alloys in as-cast and isothermally treated states was investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） equipped with energy dispersive spectroscope （EDS）, and transmission electron microscopy （TEM）. The typical solidification characteristics are due to the joint influence of both the crystal temperature range and the solidification path. The wide crystallization temperature range contributes to obtaining coarse dendrites in the as-cast Ti47A17Nb2.5V1.0Cr （at%） alloy solidifying through the peritectic reaction. The β-solidifying Ti46A17Nb2.5V1.0Cr （at%） alloy with the narrow crystallization temperature range is attributed to the formation of a homogeneous finegrained microstructure. However, the crystallization temperature range of Ti48A17Nb2.5V1.0Cr （at%） alloy is equivalent to that of Ti46A17Nb2.5V1.0Cr alloy, but it is solidified by peritectic reaction, leading to the formation of finer dendrites.展开更多
The microstructural evolution and creep deformation behavior which were adjusted and controlled by age treatment of a novel Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si(mole fraction,%)alloy,were investigated.The microstructures wer...The microstructural evolution and creep deformation behavior which were adjusted and controlled by age treatment of a novel Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si(mole fraction,%)alloy,were investigated.The microstructures were obtained at different heat treatment temperatures and analyzed by SEM and TEM techniques.The creep behavior of the alloy was studied at 650℃,150 MPa for 100 h in air.The results showed that the initial microstructure mainly contained lath-likeα2,B2,and O phases.The precipitated O phase was sensitive to aging temperature.With the aging temperature increasing,the thickness of the precipitated O phase was also increased,and the length was shortened.The creep resistance of this alloy was relevant to the morphology and volume faction of the lamellar O phase.The increase of lamellar O phase in thickness was the main reason for the improved creep properties.展开更多
Background: This study investigated changes in rumen protozoal and methanogenic communities, along with the correlations among microbial taxa and methane(CH_4) production of six Belmont Red Composite beef steers fed t...Background: This study investigated changes in rumen protozoal and methanogenic communities, along with the correlations among microbial taxa and methane(CH_4) production of six Belmont Red Composite beef steers fed tea seed saponins(TSS). Animals were fed in three consecutive feeding periods, a high-grain basal diet for 14 d(BD period) then a period of progressive addition of TSS to the basal diet up to 30 g/d for 20 d(TSS period), followed by the basal diet for 13 d without TSS(BDP post-control period).Results: The study found that TSS supplementation decreased the amount of the protozoal genus Entodinium and increased Polyplastron and Eudiplodinium genera. During BDP period, the protozoa community of steers did not return to the protozoal profiles observed in BD period, with higher proportions of Metadinium and Eudiplodinium and lower Isotricha. The addition of TSS was found to change the structure of methanogen community at the subgenus level by decreasing the abundance of methanogens in the SGMT clade and increasing the abundance of methanogens in the RO clade. The correlation analysis indicated that the abundance of SGMT clade methanogens were positively correlated with Isotricha, and Isotricha genus and SGMT clade methanogens were positively correlated with CH_4 production. While RO clade were positively correlated with the proportion of Metadinium genus, which was negatively correlated with CH_4 emission.Conclusions: These results suggest that different genera of rumen protozoa ciliates appear to be selectively inhibited by TSS, and the change in methanogen community at the subgenus level may be due to the mutualistic relationships between methanogens and rumen ciliates.展开更多
The effect of molten salts on the mechanical properties of a Ni–20Cr–18W(wt%)-based superalloy was investigated in this work. The hot corrosion characteristics and the microstructural evolution during the hot corros...The effect of molten salts on the mechanical properties of a Ni–20Cr–18W(wt%)-based superalloy was investigated in this work. The hot corrosion characteristics and the microstructural evolution during the hot corrosion process were analyzed. The corrosion scale forms on the surface of the substrate, and its thickness increases gradually during the process. The element of S invades the substrate. The corrosion products mainly include Ni O,Ni_3S_2 and Cr_2O_3. The hot corrosion in molten salt makes the specimens rough and flawed. The serration grain boundaries are observed in the hot corroded specimens.The tensile strength and elongation of the original alloy are^1023 MPa and ~15 %, respectively. After corroded for5 h, the tensile strength and elongation of the specimen decrease to ~771 MPa and ~7 % and diminish to^814 MPa and ~9 % for the specimen corroded for 10 h.The hot corrosion process deteriorates the mechanical properties of the alloys. And the tensile strength and elongation of the specimen corroded for 20 h sharply decrease to ~539 MPa and ~3 %, respectively. The nonmonotonic variation of the mechanical properties of the specimen occurs for the specimens corroded for 10 h,which is related to the competition between the depredation of the molten salts and the strengthening process by carbides and the serrated grain boundaries.展开更多
The monolithic foamed propellants with high densities were prepared by casting and two-step foaming processes.Glycidyl azide polymer(GAP)and isocyanate were used as the binder system and 2,4,6,8,10,12-hexanitro-2,4,6,...The monolithic foamed propellants with high densities were prepared by casting and two-step foaming processes.Glycidyl azide polymer(GAP)and isocyanate were used as the binder system and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW,CL-20)was employed as the energetic component.The newly designed formulation containing 60%CL-20 produced a force constant of 1077 J/g and low flame temperature of 2817 K.Two foamed propellants with densities of 1.32 g/cm^(3)and 1.53 g/cm^(3)were fabricated by a confined foaming process and examined by closed bomb tests.The results revealed that porosity significantly affects burning performance.A size effect on combustion behaviors was observed for the foamed propellant with 5.56%porosity,and a double-hump progressive dynamic vivacity curve was obtained.At last,the 30 mm gun test was carried out to demonstrate the interior ballistic performance,and the muzzle velocity increased by 120 m/s at the same maximum chamber pressure when monolithic propellant was added in the charge.展开更多
Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated.Tensile creep experiments were performed at 800,850 an...Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated.Tensile creep experiments were performed at 800,850 and 900℃ under 150 MPa in air.Microstructures before and after creep tests were examined using scanning and transmission electron microscopy(SEM and TEM).Dislocations within the lamellar structure andβo(ω)region and twin intersection in massiveγgrains were investigated.Dislocation sliding played a critical role in the deformation ofωo phase,which preferentially occurred on the(0002)ωo plane.Possible deformation mechanisms were revealed.A stress-inducedγ→α2 phase transformation took place during the creep test at 850 and 900℃.α2 lamella could directly decompose into theωo phase at 850℃.The instability of high-temperature microstructure can weaken the creep resistance and promote the plastic deformation of the lamellar matrix,thus could be detrimental to the creep properties.The correlations between creep properties and microstructure instability were discussed.展开更多
Cadmium(Cd)accumulation in rice grain is of health concern.Identifying genes involved in grain Cd accumulation and performing molecular breeding may reduce it.In this study,knockout of OsNRAMP2,a member of the NRAMP f...Cadmium(Cd)accumulation in rice grain is of health concern.Identifying genes involved in grain Cd accumulation and performing molecular breeding may reduce it.In this study,knockout of OsNRAMP2,a member of the NRAMP family,reduced grain Cd concentrations by more than 38%,and overexpressing OsNRAMP2 increased grain Cd concentrations by more than 50%.Physiological experiments showed that OsNRAMP2 facilitated Cd translocation from root to shoot by positively regulating Cd efflux from the vacuoles.At filling stage,OsNRAMP2 was highly expressed in all tissues except for husk,suggesting its role in Cd remobilization.Changes in OsNRAMP2 expression affected the concentrations of Fe,Mn,Zn,and Cu in grain and also affected rice growth.Phylogenetic analysis showed that the distribution of OsNRAMP2 haplotypes between japonica and indica was different.Among the four haplotypes of OsNRAMP2,Hap 1,with a 6-bp nucleotide insertion in exon 1,had grain Cd concentration at least 45.3%lower than any of the other three haplotypes.Almost all(99.3%)japonica accessions but rare indica accessions(4.44%)from the 3K sequenced rice genomes carry Hap 1 of OsNRAMP2.Our study sheds light on the molecular mechanism of grain Cd accumulation and provides a promising target for low-Cd rice breeding.展开更多
Nonlinear optics,which is a subject for studying the interaction between intense light and materials,has great impact on various research fields.Since many structures in biological tissues exhibit strong nonlinear opt...Nonlinear optics,which is a subject for studying the interaction between intense light and materials,has great impact on various research fields.Since many structures in biological tissues exhibit strong nonlinear optical effects,nonlinear optics has been widely applied in biomedical studies.Especially in the aspect of bio-imaging,nonlinear optical techniques can provide rapid,label-free and chemically specific imaging of biological samples,which enable the investigation of biological processes and analysis of samples beyond other microscopy techniques.In this review,we focus on the introduction of nonlinear optical processes and their applications in bio-imaging as well as the recent advances in this filed.Our perspective of this field is also presented.展开更多
基金the National Natural Science Foundation of China(NSFC),Grant/Award Number:32272909Discipline Construction Program in Sichuan Agricultural University(2221993012)China Agriculture(Beef Cattle/Yak)Research System of MOF and MARA(CARS-37)。
文摘Background As a unique livestock adapted to the harsh environment,grazing yaks frequently suffer from malnutrition and even death because of the lower yield and quality of forage in the Qinghai-Tibet Plateau during the cold season.Certain stress conditions,such as environmental changes,disease,and malnutrition,can lead to a decrease in glutamine(Gln)synthesis,which fails to cover the physiological needs of the organism.Supplementation with exogenous Gln can promote nutrient digestion and improve rumen fermentation in ruminant animals under malnutrition.However,whether Gln could alleviate the barrier function injury induced by malnutrition and its mechanism is still unclear.Methods In the in vivo experiments,24 healthy yaks(31 months,265.35±25.81 kg)were randomly divided into 3 groups,namely control group(Con,free access to the basal diet),feed restriction group(FR,50% level of ad libitum feed intake),and feed restriction+Gln group(FR+Gln,50% level of ad libitum feed intake from d 1 to 30,50% level of ad libitum feed intake+1%Gln from d 31 to 60).In the in vitro experiments,the yak rumen epithelial cells(YRECs)were divided into 4 groups:Con group(complete medium),Gln group(complete medium+10 mmol/L Gln),Gln deficiency group(Gln-D,Gln-free medium),and Gln deficiency+Gln group(Gln-D+Gln,Gln-free medium+10 mmol/L Gln).Results In the in vivo experiments,FR significantly decreased the ruminal concentrations of acetate,propionate,butyrate,iso-butyrate,and total volatile fatty acid(VFA)(P<0.05).FR also reduced the m RNA expression of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase,and the concentrations of lactate,histone acetyltransferase(p300),histone deacetylase(HDAC),as well as the histone lysine lactylation level compared to Con group,while Gln supplementation alleviated them(P<0.05).In the in vitro experiments,Gln alleviated the Gln-D-induced down-regulation of NHE1,Na^(+)/K^(+)-ATPase,and Ca^(2+)/Mg^(2+)-ATPase m RNA expressions and reduction of lactate,p300,HDAC concentrations,and histone lysine lactylation level(P<0.05).Besides,p300 inhibitor abrogated Gln repair of barrier function damage in YRECs(P<0.05).Conclusions Overall,our results revealed the potential mechanism of Gln supplementation to repair malnutritioninduced damage of rumen epithelial barrier function in yaks,which might be related to histone lysine lactylation.However,because we do not have a control group receiving glutamine alone,we cannot determine the impact of Gln on the rumen epithelial function of normal yaks.
基金Financial supports from the National Natural Science Foundation of China (Nos.22025109,22371283)the National Key R&D Program of China (No.2023YFA1507902)+1 种基金CAS Project for Young Scientists in Basic Research (No.YSBR-050)the State Key Laboratory of Fine Chemicals,Dalian University of Technology (No.KF2102) are gratefully acknowledged。
文摘The direct transformation of dinitrogen(N_(2)) into nitrogen-containing organic compounds holds substantial importance.In this work,we report a titanium-promoted method for the conversion of N_(2) to N-methylimides.Initially,the N_(2)-bridging end-on dititanium side-on dipotassium complex[{(Tren^(TMS))Ti}_(2)(μ-η^(1):η^(1):η^(2):η^(2)-N_(2)K_(2))] underwent simultaneous disproportionation and N-methylation reactions in the presence of methyl trifluoromethanesulfonate(Me OTf),yielding [{(N^(Me,TMS)NN^(TMS)_(2))Ti}(μ-NMe)]_(2) with complete cleavage of the N≡N bond.The nucleophilicity of the N-methylated intermediate allowed it to react with electrophilic reagents such as trimethylchlorosilane(TMSCl) to form heptamethyldisilazane,or with acyl chlorides to generate N-methylimides.Moreover,nitrogen-15(^(15)N) labeled experiments provided a novel approach to synthesizing ^(15)N-labeled methylimides.
文摘OBJECTIVE Oxidative sress is one of the key factor responsible for occurrence and development of hepatic fibrosis,a common consequence of chronic liver injury of multiple etiology.Nuclear factor erythroid 2-related factor 2(Nrf2)serves as a major regulator of a celular defense system against oxidative stress.Xiaochaihutang(XCHT),a compound of seven botanical extracts used for liver diseases traditionally in East Asia.However,few studies have investigated its anti-hepatic fibrosis effects and pathophysiological mechanism of action.The present study was designed to confirm the anti-hepatic fibrosis effects and explore its potential mechanism of action by investigating the intervention of Nrf2 pathway.METHODS Liver fibrosis was induced by repeated injection of Carbon tetrachloride(CCl4) over a period of 9 weeks.Starting from the 6 th week,the animals in treatment groups were given the appropriate dose of XCHT granules and silybin.Biochemical parameters,histological changes of the liver and alpha-smooth muscle actin(α-SMA) were determined.The expressions of Nrf2,Keap1,Nqo1,HO-1,Gclc and Gclm were assessed by RT-PCR and Western blot.RESULTS CCl4 caused a significant fibrosis damage in the rat liver and the liver functions and fibrosis degree were significantly improved by XCHT(5 g·kg^(-1) and 10 g·kg^(-1)).XCHT(5 g·kg^(-1) and 10 g·kg^(-1)) treatment significantly decreased the number of cells labeled with α-SMA antibodies.Moreover,XCHT(5 g·kg^(-1) and 10 g·kg^(-1))significantly increase Nqo1,HO-1,Gclc and Gclm expressions in the liver.CONCLUSION T hese studies establish XCHT is a potentially useful therapeutic agent for treatment of hepatic fibrosis and it might be via regulation of Nrf2 pathway in rats against oxidative stress,making further efforts to inhibiting the activated HSCs.Activation or up-regulation of Nrf2 pathway may be an alternative treatment strategy for liver fibrosis.
基金funded by the National Natural Science Foundation of China(Grant No.06101213)the National Natural Science Foundation of China(Grant No.22105160).
文摘3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have been limited. This study explores the impact of poly(vinylidene fluoride) and polydopamine-coated aluminum particles on the thermal and combustion properties of 3D printed hybrid rocket fuels. Physical self-assembly and anti-solvent methods were employed for constructing composite μAl particles. Characterization using SEM, XRD, XPS, FTIR, and μCT revealed a core-shell structure and homogeneous elemental distribution. Thermal analysis showed that PVDF coatings significantly increased the heat of combustion for aluminum particles, with maximum enhancement observed in μAl@PDA@PVDF(denoted as μAl@PF) at 6.20 k J/g. Subsequently, 3D printed fuels with varying pure and composite μAl particle contents were prepared using 3D printing. Combustion tests indicated higher regression rates for Al@PF/Resin composites compared to pure resin, positively correlating with particle content. The fluorocarbon-alumina reaction during the combustion stage intensified Al particle combustion, reducing residue size. A comprehensive model based on experiments provides insights into the combustion process of PDA and PVDF-coated droplets. This study advances the design of 3D-printed hybrid rocket fuels, offering strategies to improve regression rates and energy release, crucial for enhancing solid fuel performance for hybrid propulsion.
基金Supported by Guiding Project of Hebei Provincial Health Commission,No.20201190 and 20180220.
文摘BACKGROUND Effective health management for high-risk stroke populations is essential.The hospital-community-home(HCH)collaborative health management(CHM)model leverages resources from hospitals,communities,and families.By integrating patient information across these three domains,it facilitates the delivery of tailored guidance,health risk assessments,and three-in-one health education.AIM To explore the effects of the HCH-CHM model on stroke risk reduction in highrisk populations.METHODS In total,110 high-risk stroke patients screened in the community from January 2019 to January 2023 were enrolled,with 52 patients in the control group receiving routine health education and 58 in the observation group receiving HCH-CHM model interventions based on routine health education.Stroke awareness scores,health behavior levels,medication adherence,blood pressure,serum biochemical markers(systolic/diastolic blood pressure,total cholesterol,and triglyceride),and psychological measures(self-rating anxiety/depression scale)were evaluated and compared between groups.RESULTS The observation group showed statistically significant improvements in stroke awareness scores and health behavior levels compared to the control group(P<0.05),with notable enhancements in lifestyle and dietary habits(P<0.05)and reductions in postintervention systolic blood pressure,diastolic blood pressure,total cholesterol,triglyceride,self-rating anxiety scale,and self-rating depression scale scores(P<0.05).CONCLUSION The HCH-CHM model had a significant positive effect on high-risk stroke populations,effectively increasing disease awareness,improving health behavior and medication adherence,and appropriately ameliorating blood pressure,serum biochemical marker levels,and negative psychological symptoms.
基金financially supported by the National Natural Science Foundation of China(No.51971176)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX2022036).
文摘This study comprehensively studied the precipitation ofαlaths and formation of inducedγnanotwins in a cast Ti-48Al-3Nb-1.5Ta(at.%)alloy tempered at theα+γphase region.The evolution of the microstruc-ture and its corresponding atomic mechanisms were investigated by transmission electron microscopy.The results show thatαphase precipitates as intersected laths,nucleates at stacking faults,and grows by a diffusion-controlled ledge-kink-terrace mechanism.The precipitation ofαlath introduces high stress concentrations at theγ/αinterface,produces dislocations and stacking faults,and induces the formation ofγnanotwins.Theγnanotwins nucleate at stacking faults emitted from theγ/αinterface and grow by Frank partials climbing,Schockley partials gliding,and several new mechanisms related to non-planar reactions of dislocations and annihilation of antiphase boundaries.Theγnanotwins are limited to sub-microns due to the lack of driving force.High temperatures promote the formation ofγnanotwins by activating non-planar reactions of dislocations and atom diffusion.In addition,Nb and Ta can promoteαlath precipitation andγnanotwin formation by reducing the stacking fault energy and preferring stacking fault emission.In summary,these findings provide new insights intoαlath precipitation andγtwinning mechanisms,which are relevant as theoretical bases for microstructure control and refinement of castγ-TiAl alloys.
基金financial support from the Equipment Pre-research Project(51312030507).
文摘This study investigates the fatigue crack propagation mechanism of a new high-strength and high-tough Ti-Mo-Cr-V-Nb-Al titanium alloy with three types of microstructures(basketweave structure,lamellar structure,and bimodal structure)through fatigue crack propagation rate tests and fatigue threshold value tests.The resistance of the alloy to fatigue crack propagation was found to be closely correlated with the morphology and distribution ofαparticles,as evidenced by microscopic examination of fracture surfaces and analysis of crack propagation paths.The primaryαparticles demonstrated superior resistance to crack propagation compared to the secondaryαparticles.The basketweave structure showed exceptional resistance to fatigue crack propagation at all stages.The lamellar structure mainly resists long crack propagation during rapid propagation,and its threshold value is the lowest,which makes it easy to produce microcrack propagation.On the contrary,the bimodal structure has the highest threshold value among the three,so its resistance to short crack growth is more excellent,but it has the highest crack growth rate in the higher stress intensity factor range.Theαparticles in the three microstructures also undergo rotational motion relative to the force axis during fatigue crack propagation,thereby adjusting the uneven stress distribution betweenα/βphases through slip behavior and further coordinating deformation.
基金financially supported by the National Key R&D Program of China(No.2021YFC2202300)the National Natural Science Foundation of China(NSFC)(No.51974258)the National College Students Innovation and Entrepreneurship Training Program(No.S202210699134).
文摘Gold-platinum(Au-Pt)alloy has aroused considerable attention due to its ultra-low magnetic susceptibility(MS)in testing mass(TM)on spacecraft.However,the effect of Au content on the properties of the alloy has not yet been understood.In this study,the composition design of Au-Pt alloy with ultra-low MS was achieved through density functional theory(DFT)and experimental methods.The elastic,thermal properties and electronic structure were systematically investigated,the composition range was further optimized and Au75Pt25 was determined to be the most suitable alloy for TM material.The phase composition of this alloy after cold rolling and solid solution was characterized,indicating a single-phase FCC structure.In addition,there is a good validation between the experimental Vickers hardness and the DFT results.This work provides new insights into the compositional optimization of Au-Pt alloys and lays the foundation for alloy development.
基金supported by the China Postdoctoral Science Foundation(No.2014m561331)Science and Technology Research Project of Heilongjiang Provincial Education Department(No.12521073)National Natural Science Youth Fund(No.61300115).
文摘In the field of organic synthesis,the core objective of retrosynthetic methods is to deduce possible synthetic routes and precursor molecules for complex target molecules.Traditional retrosynthetic methods,such as template-based retrosynthesis,have high accuracy and interpretability in specific types of reactions but are limited by the scope of the template library,making it difficult to adapt to new or uncommon reaction types.Moreover,sequence-to-sequence retrosynthetic prediction methods,although they enhance the flexibility of prediction,often overlook the complexity of molecular graph structures and the actual interactions between atoms,which limits the accuracy and reliability of the predictions.To address these limitations,this paper proposes a Molecular Retrosynthesis Top-k Prediction based on the Latent Generation Process(MRLGP)that uses latent variables from graph neural networks to model the generation process and produce diverse set of reactants.Utilising an encoding method based on Graphormer,the authors have also introduced topology-aware positional encoding to better capture the interactions between atomic nodes in the molecular graph structure,thereby more accurately simulating the retrosynthetic process.The MRLGP model significantly enhances the accuracy and diversity of predictions by correlating discrete latent variables with the reactant generation process and progressively constructing molecular graphs using a variational autoregressive decoder.Experimental results on benchmark datasets such as USPTO-50k,USPTO-Full,and USPTO-DIVERSE demonstrate that MRLGP outperforms baseline models on multiple Top-k evaluation metrics.Additionally,ablation experiments conducted on the USPTO-50K dataset further validate the effectiveness of the methods used in the encoder and decoder parts of the model.
基金sponsored by the National Key Research and Development Program of China(No.2018YFB0704400)Key Research Project of Zhejiang Laboratory,China(No.2021PE0AC02)+1 种基金Key Program of Science and Technology of Yunnan Province,China(Nos.202002AB080001-2,202102AB080019-3)Key Project of Shanghai Zhangjiang National Independent Innovation Demonstration Zone,China(No.ZJ2021-ZD-006)。
基金financially supported by the National Basic Research Program of China(No.2011CB605503)the Program of Introducing Talents of Discipline to Universities(No.B08040)
文摘The effect of A1 content on the microstructure and solidification characteristics of Ti-A1-Nb-V-Cr alloys in as-cast and isothermally treated states was investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） equipped with energy dispersive spectroscope （EDS）, and transmission electron microscopy （TEM）. The typical solidification characteristics are due to the joint influence of both the crystal temperature range and the solidification path. The wide crystallization temperature range contributes to obtaining coarse dendrites in the as-cast Ti47A17Nb2.5V1.0Cr （at%） alloy solidifying through the peritectic reaction. The β-solidifying Ti46A17Nb2.5V1.0Cr （at%） alloy with the narrow crystallization temperature range is attributed to the formation of a homogeneous finegrained microstructure. However, the crystallization temperature range of Ti48A17Nb2.5V1.0Cr （at%） alloy is equivalent to that of Ti46A17Nb2.5V1.0Cr alloy, but it is solidified by peritectic reaction, leading to the formation of finer dendrites.
基金Project(51601146)supported by the National Natural Science Foundation of ChinaProject(2017M613234)supported by the China Postdoctoral Science Foundation
文摘The microstructural evolution and creep deformation behavior which were adjusted and controlled by age treatment of a novel Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si(mole fraction,%)alloy,were investigated.The microstructures were obtained at different heat treatment temperatures and analyzed by SEM and TEM techniques.The creep behavior of the alloy was studied at 650℃,150 MPa for 100 h in air.The results showed that the initial microstructure mainly contained lath-likeα2,B2,and O phases.The precipitated O phase was sensitive to aging temperature.With the aging temperature increasing,the thickness of the precipitated O phase was also increased,and the length was shortened.The creep resistance of this alloy was relevant to the morphology and volume faction of the lamellar O phase.The increase of lamellar O phase in thickness was the main reason for the improved creep properties.
基金supported by grants from the Natural Science Foundation of China (31272472)project grants from Meat & Livestock Australia,Fisheries and Forestry in Australia and Commonwealth Scientific and Industrial Research Organization (CSIRO)。
文摘Background: This study investigated changes in rumen protozoal and methanogenic communities, along with the correlations among microbial taxa and methane(CH_4) production of six Belmont Red Composite beef steers fed tea seed saponins(TSS). Animals were fed in three consecutive feeding periods, a high-grain basal diet for 14 d(BD period) then a period of progressive addition of TSS to the basal diet up to 30 g/d for 20 d(TSS period), followed by the basal diet for 13 d without TSS(BDP post-control period).Results: The study found that TSS supplementation decreased the amount of the protozoal genus Entodinium and increased Polyplastron and Eudiplodinium genera. During BDP period, the protozoa community of steers did not return to the protozoal profiles observed in BD period, with higher proportions of Metadinium and Eudiplodinium and lower Isotricha. The addition of TSS was found to change the structure of methanogen community at the subgenus level by decreasing the abundance of methanogens in the SGMT clade and increasing the abundance of methanogens in the RO clade. The correlation analysis indicated that the abundance of SGMT clade methanogens were positively correlated with Isotricha, and Isotricha genus and SGMT clade methanogens were positively correlated with CH_4 production. While RO clade were positively correlated with the proportion of Metadinium genus, which was negatively correlated with CH_4 emission.Conclusions: These results suggest that different genera of rumen protozoa ciliates appear to be selectively inhibited by TSS, and the change in methanogen community at the subgenus level may be due to the mutualistic relationships between methanogens and rumen ciliates.
基金financially supported by the National Natural Science Foundation of China (No. 51171150)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities (No. B08040)
文摘The effect of molten salts on the mechanical properties of a Ni–20Cr–18W(wt%)-based superalloy was investigated in this work. The hot corrosion characteristics and the microstructural evolution during the hot corrosion process were analyzed. The corrosion scale forms on the surface of the substrate, and its thickness increases gradually during the process. The element of S invades the substrate. The corrosion products mainly include Ni O,Ni_3S_2 and Cr_2O_3. The hot corrosion in molten salt makes the specimens rough and flawed. The serration grain boundaries are observed in the hot corroded specimens.The tensile strength and elongation of the original alloy are^1023 MPa and ~15 %, respectively. After corroded for5 h, the tensile strength and elongation of the specimen decrease to ~771 MPa and ~7 % and diminish to^814 MPa and ~9 % for the specimen corroded for 10 h.The hot corrosion process deteriorates the mechanical properties of the alloys. And the tensile strength and elongation of the specimen corroded for 20 h sharply decrease to ~539 MPa and ~3 %, respectively. The nonmonotonic variation of the mechanical properties of the specimen occurs for the specimens corroded for 10 h,which is related to the competition between the depredation of the molten salts and the strengthening process by carbides and the serrated grain boundaries.
文摘The monolithic foamed propellants with high densities were prepared by casting and two-step foaming processes.Glycidyl azide polymer(GAP)and isocyanate were used as the binder system and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW,CL-20)was employed as the energetic component.The newly designed formulation containing 60%CL-20 produced a force constant of 1077 J/g and low flame temperature of 2817 K.Two foamed propellants with densities of 1.32 g/cm^(3)and 1.53 g/cm^(3)were fabricated by a confined foaming process and examined by closed bomb tests.The results revealed that porosity significantly affects burning performance.A size effect on combustion behaviors was observed for the foamed propellant with 5.56%porosity,and a double-hump progressive dynamic vivacity curve was obtained.At last,the 30 mm gun test was carried out to demonstrate the interior ballistic performance,and the muzzle velocity increased by 120 m/s at the same maximum chamber pressure when monolithic propellant was added in the charge.
基金financially supported by the National Natural Science Foundation of China(Nos.51774238 and51971176)the 2018 Joint Foundation of Ministry of Education for Equipment Pre-research(No.6141A020332)+1 种基金the State Key Laboratory for Advanced Metal and Materials Foundation(No.2014-ZD06)the Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou University(No.LZUMMM2020008)。
文摘Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated.Tensile creep experiments were performed at 800,850 and 900℃ under 150 MPa in air.Microstructures before and after creep tests were examined using scanning and transmission electron microscopy(SEM and TEM).Dislocations within the lamellar structure andβo(ω)region and twin intersection in massiveγgrains were investigated.Dislocation sliding played a critical role in the deformation ofωo phase,which preferentially occurred on the(0002)ωo plane.Possible deformation mechanisms were revealed.A stress-inducedγ→α2 phase transformation took place during the creep test at 850 and 900℃.α2 lamella could directly decompose into theωo phase at 850℃.The instability of high-temperature microstructure can weaken the creep resistance and promote the plastic deformation of the lamellar matrix,thus could be detrimental to the creep properties.The correlations between creep properties and microstructure instability were discussed.
基金supported by the National Natural Science Foundation of China(31901488)the Guangdong Basic and Applied Basic Research Foundation(2020A1515010193)+3 种基金the Innovation Team Project of Guangdong Modern Agricultural Industrial System(2021KJ106,2022KJ106)the Scientific and Technological Plan of Guangzhou(201804020078,202102021005)the Special fund for scientific innovation strategy-construction of high level Academy of Agriculture Science(R2021PY-QF002,202027,R2019-JX001,R2021PY-QF001)the Guangdong Key Laboratory of New Technology in Rice Breeding(2020B1212060047).
文摘Cadmium(Cd)accumulation in rice grain is of health concern.Identifying genes involved in grain Cd accumulation and performing molecular breeding may reduce it.In this study,knockout of OsNRAMP2,a member of the NRAMP family,reduced grain Cd concentrations by more than 38%,and overexpressing OsNRAMP2 increased grain Cd concentrations by more than 50%.Physiological experiments showed that OsNRAMP2 facilitated Cd translocation from root to shoot by positively regulating Cd efflux from the vacuoles.At filling stage,OsNRAMP2 was highly expressed in all tissues except for husk,suggesting its role in Cd remobilization.Changes in OsNRAMP2 expression affected the concentrations of Fe,Mn,Zn,and Cu in grain and also affected rice growth.Phylogenetic analysis showed that the distribution of OsNRAMP2 haplotypes between japonica and indica was different.Among the four haplotypes of OsNRAMP2,Hap 1,with a 6-bp nucleotide insertion in exon 1,had grain Cd concentration at least 45.3%lower than any of the other three haplotypes.Almost all(99.3%)japonica accessions but rare indica accessions(4.44%)from the 3K sequenced rice genomes carry Hap 1 of OsNRAMP2.Our study sheds light on the molecular mechanism of grain Cd accumulation and provides a promising target for low-Cd rice breeding.
基金the National Natural Science Foundation of China(61722508/61525503/61620106016/61835009/61935012/61961136005)(Key)Project of Department of Education of Guangdong Province(2016KCXTD007)Shenzhen Basic Research Project(JCYJ20180305124902165).
文摘Nonlinear optics,which is a subject for studying the interaction between intense light and materials,has great impact on various research fields.Since many structures in biological tissues exhibit strong nonlinear optical effects,nonlinear optics has been widely applied in biomedical studies.Especially in the aspect of bio-imaging,nonlinear optical techniques can provide rapid,label-free and chemically specific imaging of biological samples,which enable the investigation of biological processes and analysis of samples beyond other microscopy techniques.In this review,we focus on the introduction of nonlinear optical processes and their applications in bio-imaging as well as the recent advances in this filed.Our perspective of this field is also presented.
