AIM: Most studies on the immune effect of gp96 were focused on its enhancement of CTLs. It is interesting to know whether gp96 could influence the humoral immune response, and whether the recombinant N-terminal fragme...AIM: Most studies on the immune effect of gp96 were focused on its enhancement of CTLs. It is interesting to know whether gp96 could influence the humoral immune response, and whether the recombinant N-terminal fragment of gp96 could substitute native gp96 to stimulate the immune system.METHODS: gp96 isolated from livers of normal mice and its N-terminal fragment (amino acid 22-355) expressed in E coli were used for immunization of BALb/c mice. Eight groups of mice received one of the following regiments subcutaneously in 100 μL phosphate buffered saline (PBS)at an interval of 3 wk. Group 1: PBS only; group 2:gp96 only; group 3: N-terminal fragment only; group 4: HBsAg only; group 5: HBsAg+gp96; group 6: HBsAg+N-terminalfragment; group 7: HBsAg+incomplete Freud's adjuvant; group 8: HBsAg+N-terminal fragment (95 ℃ heated for 30 min). Serum anti-HBsAg antibody levels were assayed by ELISA. CTL responses in splenocytes were analyzed by ELISPOT after the last vaccination.RESULTS: The average titer of serum anti-HBsAg antibodyin the mice immunized with HBsAg together with gp96 or its N-terminal fragment were much higher than those immunized with HBsAg alone detected by ELISA. The cellular immune response of the mice immunized with HBsAg together with gp96 or its N-terminal fragment was not different with those immunized with HBsAg alone measured by ELISPOT assay.CONCLUSION: gp96 or its N-terminal fragment greatly improved humoral immune response induced by HBsAg, but failed to enhance the CTL response, which demonstrated the potential of using gp96 or its N-terminal fragment as a possible adjuvant to augment humoral immune response against HBV infection.展开更多
Our previous results indicated that both the secreted and the intracellular form of full length and 1-97 N-terminal fragment of IGFBP-3 induce apoptosis in PC-3 human prostate cancer cells in an IGF-dependent and inde...Our previous results indicated that both the secreted and the intracellular form of full length and 1-97 N-terminal fragment of IGFBP-3 induce apoptosis in PC-3 human prostate cancer cells in an IGF-dependent and independent manner. This study was undertaken to delineate possible down-stream signaling pathways that are involved in this process. Intact IGFBP-3 and its N-terminal 1-97 fragments with or without a signal propeptide were fused to YFP and expressed in PC-3 human prostate cancer cells. In some cases, the putative IGF-binding site was presented in full length IGFBP-3 and its N-terminal fragment was also mutated. Extent of apoptosis was quantified using FACS. Up-regulation of total Stat-1 and activation of phospho-Stat-1 were shown by western blot. TGF-β signal was measured by luciferase reporter assay. Results from inhibitor studies indicated that both the Caspase 8 and caspase 9 pathways are involved in IGFBP-3 (non-secreted form) which induced apoptosis in PC-3 cells. Exogenous addition of IGFBP-3 to PC-3 cells increased Stat-1 protein expression/tyrosine phosphorylation. Interestingly, results also showed that knockdown of Stat-1 by siRNA potentiated the IGFBP-3 induced apoptosis in PC-3 cells. In addition, both full-length IGFBP-3 and its 1-97 Nterminal fragments inhibited TGF-β signaling in these cells. This is the first report that compares the signal transduction pathways involved in apoptotic pathways mediated by IGFBP-3 in PC-3 human prostate cancer cells. Non-secreted form of full length IGFBP-3 and its N-terminal fragments induced apoptosis in PC-3 cells via activation of caspase 8 and caspase 9. Although, only non-secreted form of IGFBP-3 is involved in inducing apoptosis in PC-3 cells via caspase 8 and caspase 9 activation pathways but both secreted and non-secreted forms of IGFBP-3 are involved in modulating Stat-1 and TGF-β pathways to induce apoptotic actions in PC-3 cells. Non-secreted intact IGFBP-3 and its N-terminal fragments induced apoptosis in PC-3 cells via activation of caspase 8 and caspase 9 pathways. Modulation in STAT-1 and TGF-β pathways may also be important for IGFBP-3 induced apoptosis in PC-3 cells in general. These studies clearly demonstrate that secreted and non-secreted FL and 1-97 N-terminal fragments induce apoptosis in PC-3 cells by regulating different mechanistic pathways.展开更多
Background Elevated N-terminal pro-brain natriuretic peptide(NT-pro-BNP)is a recognized predictor of poor prognosis in heart failure and infectious diseases.We aimed to investigate its predictive value for short-term ...Background Elevated N-terminal pro-brain natriuretic peptide(NT-pro-BNP)is a recognized predictor of poor prognosis in heart failure and infectious diseases.We aimed to investigate its predictive value for short-term mortality in patients with infective endocarditis(IE)complicated by sepsis.Methods A total of 416 consecutive patients diagnosed with IE and sepsis at Guangdong Provincial People's Hospital were enrolled.The patients were divided into three groups according to the tertiles of NT-pro-BNP level of the first blood collection within 24 hours after admission:<2000 pg/mL(n=138),2000-7167 pg/mL(n=140),and>7167 pg/mL(n=138).Univariate and multivariate regression analysis were used to explore the predictive value of NT-pro-BNP for short-term mortality,and the best cut-off value was determined by receiver operating characteristic(ROC)curve.Results In-hospital and 6-month death occurred in 65 and 94 patients,respectively.Higher in-hospital mortality was found in patients with higher serum NT-pro-BNP levels(9.4%vs.13.6%vs.23.9%,P=0.003).ROC curve analysis identified an optimal NT-pro-BNP cutoff level of 1357 pg/mL[area under curve(AUC):0.652,95%CI:0.588-0.717,P<0.001].Multivariate regression analysis showed that both log-transformed NT-pro-BNP(in-hospital mortality:OR:1.987,95%CI:1.045-3.778,P=0.036;6-month mortality:HR:1.714,95%CI:1.072-2.7400,P=0.025)and NT-pro-BNP>1357 pg/mL(in-hospital mortality:OR:8.059,95%CI:1.813-35.818,P=0.006;6-month mortality:HR:5.193,95%CI:1.806-14.938,P=0.002)were both independent risk factors for in-hospital and 6-month mortality.Conclusions Serum NT-pro-BNP could serve as an independent predictor of in-hospital and 6-month mortality in patients with IE complicated with sepsis.展开更多
Dopamine β-monooxygenase N-terminal(DOMON)domain-containing genes are present across all taxa and are critical in cell signaling and redox transport.Despite their significance,these genes remain understudied in plant...Dopamine β-monooxygenase N-terminal(DOMON)domain-containing genes are present across all taxa and are critical in cell signaling and redox transport.Despite their significance,these genes remain understudied in plant species.In this study,we identified 15 DOMON genes in rice and analyzed their phylogenetic relationships,conserved motifs,and cis-regulatory elements.Phylogenetic analysis revealed distinct clustering of OsDOMON genes in rice and other monocots,compared with Arabidopsis thaliana.Promoter analysis showed a higher abundance of stress-related regulatory elements in Tetep,a well-known blast and abiotic stress-tolerant cultivar,compared with Nipponbare and HP2216.OsDOMON genes displayed differential expression under biotic stress(Magnaporthe oryzae infection)and abiotic stresses(drought,heat,and salinity)in contrasting cultivars.Tetep exhibited significantly higher expression levels of specific OsDOMON genes during early blast infection stages,particularly OsDOMON6.1 and OsDOMON9.2,suggesting their roles in cell wall fortification and reactive oxygen species signaling.Under abiotic stress,genes like OsDOMON3.3,OsDOMON8.1,and OsDOMON9.2 showed higher expression in Tetep,indicating their involvement in stress tolerance mechanisms.This study provides a foundation for future functional studies of OsDOMON genes,paving the way for developing rice cultivars resistant to biotic and abiotic stresses.展开更多
This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key de...This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key design parameters including casing dimensions and detonation positions.The paper details the finite element analysis for fragmentation,the characterizations of the dynamic hardening and fracture models,the generation of comprehensive datasets,and the training of the ANN model.The results show the influence of casing dimensions on fragment velocity distributions,with the tendencies indicating increased resultant velocity with reduced thickness,increased length and diameter.The model's predictive capability is demonstrated through the accurate predictions for both training and testing datasets,showing its potential for the real-time prediction of fragmentation performance.展开更多
STAPHYLOCOCCAL nuclease(SNase A,EC 3.1.4.7),which hydrolyzes the phosphodiesterbond of DNA and RNA,and releases 3’-phosphate mononucleotides and dinucleotides,con-sists of 149 amino acid residues(MW=16 807)without su...STAPHYLOCOCCAL nuclease(SNase A,EC 3.1.4.7),which hydrolyzes the phosphodiesterbond of DNA and RNA,and releases 3’-phosphate mononucleotides and dinucleotides,con-sists of 149 amino acid residues(MW=16 807)without sulfhydryl and disulfide groups.SNase A was originally derived from Staphylococcus aureus.Later the gene of the enzyme wascloned and inserted into several expression systems.Its crystal structure was detected展开更多
Rock fragmentation is an important indicator for assessing the quality of blasting operations.However,accurate prediction of rock fragmentation after blasting is challenging due to the complicated blasting parameters ...Rock fragmentation is an important indicator for assessing the quality of blasting operations.However,accurate prediction of rock fragmentation after blasting is challenging due to the complicated blasting parameters and rock properties.For this reason,optimized by the Bayesian optimization algorithm(BOA),four hybrid machine learning models,including random forest,adaptive boosting,gradient boosting,and extremely randomized trees,were developed in this study.A total of 102 data sets with seven input parameters(spacing-to-burden ratio,hole depth-to-burden ratio,burden-to-hole diameter ratio,stemming length-to-burden ratio,powder factor,in situ block size,and elastic modulus)and one output parameter(rock fragment mean size,X_(50))were adopted to train and validate the predictive models.The root mean square error(RMSE),the mean absolute error(MAE),and the coefficient of determination(R^(2))were used as the evaluation metrics.The evaluation results demonstrated that the hybrid models showed superior performance than the standalone models.The hybrid model consisting of gradient boosting and BOA(GBoost-BOA)achieved the best prediction results compared with the other hybrid models,with the highest R^(2)value of 0.96 and the smallest values of RMSE and MAE of 0.03 and 0.02,respectively.Furthermore,sensitivity analysis was carried out to study the effects of input variables on rock fragmentation.In situ block size(XB),elastic modulus(E),and stemming length-to-burden ratio(T/B)were set as the main influencing factors.The proposed hybrid model provided a reliable prediction result and thus could be considered an alternative approach for rock fragment prediction in mining engineering.展开更多
Phospholipase A1(PLA1)is a kind of specific phospholipid hydrolase widely used in food,medical,textile.However,limitations in its expression and enzymatic activity have prompted the investigation of the phospholipase-...Phospholipase A1(PLA1)is a kind of specific phospholipid hydrolase widely used in food,medical,textile.However,limitations in its expression and enzymatic activity have prompted the investigation of the phospholipase-assisting protein PlaS.In this study,we elucidate the role of PlaS in enhancing the expression and activity of PlaA1 through N-terminal truncation.Our research demonstrates that truncating the N-terminal region of PlaS effectively overcomes its inhibitory effect on host cells,resulting in improved cell growth and increased protein solubility of the protein.The yeast two-hybrid assay confirms the interaction between PlaA1 and N-terminal truncated PlaS(ΔN27 PlaS),highlighting their binding capabilities.Furthermore,in vitro studies using Biacore analysis reveal a concentration-dependent and specific binding between PlaA1 andΔN27 PlaS,exhibiting high affinity.Molecular docking analysis provides insights into the hydrogen bond interactions betweenΔN27 PlaS and PlaA1,identifying key amino acid residues crucial for their binding.Finally,the enzyme activity of PLA1 was boost to 8.4 U/mL by orthogonal test.Study significantly contributes to the understanding of the interaction mechanism between PlaS and PlaA1,offering potential strategies for enhancing PlaA1 activity through protein engineering approaches.展开更多
In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Ther...In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Therefore,the fluid evolution characteristics and rock fracture behavior during jet impingement were studied.The results indicate that the breaking process of high-temperature rock by jet impact can be divided into four stages:initial fluid-solid contact stage,intense thermal exchange stage,perforation and fracturing stage,and crack propagation and penetration stage.With the increase of rock temperature,the jet reflection angles and the time required for complete cooling of the impact surface significantly decrease,while the number of cracks and crack propagation rate significantly increase,and the rock breaking critical time is shortened by up to 34.5%.Based on numerical simulation results,it was found that the center temperature of granite at 400℃ rapidly decreased from 390 to 260℃ within 0.7 s under jet impact.In addition,a critical temperature and critical heat flux prediction model considering the staged breaking of hot rocks was established.These findings provide valuable insights to guide the water jet technology assisted deep ground hot rock excavation project.展开更多
This paper proposes an efficient strategy for resource utilization in Elastic Optical Networks (EONs) to minimize spectrum fragmentation and reduce connection blocking probability during Routing and Spectrum Allocatio...This paper proposes an efficient strategy for resource utilization in Elastic Optical Networks (EONs) to minimize spectrum fragmentation and reduce connection blocking probability during Routing and Spectrum Allocation (RSA). The proposed method, Dynamic Threshold-Based Routing and Spectrum Allocation with Fragmentation Awareness (DT-RSAF), integrates rerouting and spectrum defragmentation as needed. By leveraging Yen’s shortest path algorithm, DT-RSAF enhances resource utilization while ensuring improved service continuity. A dynamic threshold mechanism enables the algorithm to adapt to varying network conditions, while its fragmentation awareness effectively mitigates spectrum fragmentation. Simulation results on NSFNET and COST 239 topologies demonstrate that DT-RSAF significantly outperforms methods such as K-Shortest Path Routing and Spectrum Allocation (KSP-RSA), Load Balanced and Fragmentation-Aware (LBFA), and the Invasive Weed Optimization-based RSA (IWO-RSA). Under heavy traffic, DT-RSAF reduces the blocking probability by up to 15% and achieves lower Bandwidth Fragmentation Ratios (BFR), ranging from 74% to 75%, compared to 77% - 80% for KSP-RSA, 75% - 77% for LBFA, and approximately 76% for IWO-RSA. DT-RSAF also demonstrated reasonable computation times compared to KSP-RSA, LBFA, and IWO-RSA. On a small-sized network, its computation time was 8710 times faster than that of Integer Linear Programming (ILP) on the same network topology. Additionally, it achieved a similar execution time to LBFA and outperformed IWO-RSA in terms of efficiency. These results highlight DT-RSAF’s capability to maintain large contiguous frequency blocks, making it highly effective for accommodating high-bandwidth requests in EONs while maintaining reasonable execution times.展开更多
Recent studies have shown that shorter periods of ejaculatory abstinence may enhance certain sperm parameters,but the molecular mechanisms underlying these improvements are still unclear.This study explored whether re...Recent studies have shown that shorter periods of ejaculatory abstinence may enhance certain sperm parameters,but the molecular mechanisms underlying these improvements are still unclear.This study explored whether reduced abstinence periods could improve semen quality,particularly for use in assisted reproductive technologies(ART).We analyzed semen samples from men with normal sperm counts(n=101)and those with low sperm motility or concentration(n=53)after 3-7 days of abstinence and then after 1-3h of abstinence,obtained from the Reproductive&Genetic Hospital of CITIC-Xiangya(Changsha,China).Physiological and biochemical sperm parameters were evaluated,and the dynamics of transfer RNA(tRNA)-derived fragments(tRFs)were analyzed using deep RNA sequencing in five consecutive samples from men with normal sperm counts.Our results revealed significant improvement in sperm motility and a decrease in the DNA fragmentation index after the 1-to 3-h abstinence period.Additionally,we identified 245 differentially expressed tRFs,and the mitogen-activated protein kinase(MAPK)signaling pathway was the most enriched.Further investigations showed significant changes in tRF-Lys-TTT and its target gene mitogen-activated protein kinase kinase 2(MAP2K2),which indicates a role of tRFs in improving sperm function.These findings provide new insights into how shorter abstinence periods influence sperm quality and suggest that tRFs may serve as biomarkers for male fertility.This research highlights the potential for optimizingART protocols and improving reproductive outcomes through molecular approaches that target sperm function.展开更多
This review examines the processes of laser heating,melting,evaporation,fragmentation,and breakdown of metal nanoparticles,as well as the dependences and values of the threshold laser parameters that initiate these pr...This review examines the processes of laser heating,melting,evaporation,fragmentation,and breakdown of metal nanoparticles,as well as the dependences and values of the threshold laser parameters that initiate these processes.Literature results are analyzed from experimental studies of these processes with gold,silver,and other nanoparticles,including laser surface melting and evaporation of nanoparticles and Coulomb fragmentation of nanoparticles by ultrashort laser pulses.A theoretical model and description of the thermal mechanisms of mentioned processes with metal(solid)nanoparticles in a liquid(solid)medium,initiated by the action of laser pulses with the threshold fluences,are presented.Comparison of the obtained results with experimental data confirms the accuracy of the model and makes it possible to use them to evaluate the parameters of laser thermal processing of nanoparticles.Applications of the processes include the laser melting,reshaping,and fragmentation of nanoparticles,the formation of nanostructures and nanonetworks,the laser processing of nanoparticles located on substrates,and their cladding on surfaces in various laser nanotechnologies.The use of laser ignition,combustion,and incandescence of nanoparticles is discussed,as is the use of nanoparticle-triggered laser breakdown for spectroscopy.These laser processes are used in photothermal nanotechnologies,nanoenergy,laser processing of nanoparticles,nonlinear optical devices,high-temperature material science,etc.In general,this review presents a modern picture of the state of laser technology and high-temperature processes with nanoparticles and their applications,being focused on the latest publications with an emphasis on recent results from 2021-2024.展开更多
We investigate distinct non-Hermitian skin effects(NHSEs)in real and Fock spaces induced by the interplay between the Hilbert space fragmentation and multiple non-Hermitian pumping channels.Using an extended Hatano–N...We investigate distinct non-Hermitian skin effects(NHSEs)in real and Fock spaces induced by the interplay between the Hilbert space fragmentation and multiple non-Hermitian pumping channels.Using an extended Hatano–Nelson model with next-nearest neighbor hopping and strong interaction as an example,we found that two fermions loaded in the lattice exhibit different real-space NHSE depending on the Hilbert space fragments to which they belong.Moreover,in the high-energy sector resulting from fragmentation,the two-particle-bound states form a one-dimensional lattice in Fock space,producing a Fock-space NHSE.At half-filling,richer patterns of Fock-space skin-like localization emerge for the different fragmented energy sectors and subsectors while realspace NHSE is suppressed by many-body effects.This study extends our understanding of the interplay between NHSE and Hilbert space fragmentation and provides detailed insights into their manifestation in interacting non-Hermitian systems.展开更多
Total or severe teratospermia affects the prognosis of fertility and causes serious problems for patients undergoing assisted reproduction[1].The pathophysiological mechanism of teratospermia is unclear.It has been sh...Total or severe teratospermia affects the prognosis of fertility and causes serious problems for patients undergoing assisted reproduction[1].The pathophysiological mechanism of teratospermia is unclear.It has been shown that patients with sperm parameters abnormalities and abnormal morphology have a high rate of fragmentation and sperm DNA decondensation[2,3],and that sperm DNA fragmentation analysis could be used as a predictor factor of fertility potential[4].展开更多
Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains com...Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains complex and not fully understood.This study aims to gain a further understanding of the energy transfer mechanism during rockfall impact and fragmentation by impact tests using a variety of rock-like sphere specimens.The experiments mainly focus on the quantitative correlation between fragmentation degree and influence factors,i.e.impact angle and velocity on steel and granite slabs.The analysis focuses on the energy distribution characteristics,energy dissipation mechanisms,and the energy conversion rate of the fragments during impact and fragmentation.The results show that there is a significant correlation between the energy conversion rate and the fragmentation degree.In normal impact tests,elasto-plastic deformation energy and fracture energy are found to be two primary categories of energy dissipation.The proportion of total kinetic energy after impact is inversely proportional to the initial energy.A comparative analysis between normal and inclined slab impact tests reveals that the impact angle significantly influences the energy conversion rate,which controls the fragmentation degree as well.In addition,the fragmentation degree is inversely proportional to the restitution coefficient.These findings contribute to a better understanding of the energy conversion mechanism during rockfall impact and fragmentation,providing valuable insight for the development of effective strategies to mitigate such rockfall hazards.展开更多
Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves a...Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.展开更多
Fragmentation is a common phenomenon in the runout process of large rockslides.Rocks have different strengths under the influence of the rock type and weathering degree,resulting in varying fragmentation characteristi...Fragmentation is a common phenomenon in the runout process of large rockslides.Rocks have different strengths under the influence of the rock type and weathering degree,resulting in varying fragmentation characteristics.However,the limited understanding of how rock strength influences the postfragmentation kinematic characteristics of rockslides is limited.Taking a natural rockslide as an example,this paper quantitatively analyzes the runout and deposition of the rockslide using the discrete element method(DEM)and examines the impacts of the rock strength on the runout and deposition characteristics of the rockslide.The results reveal that(1)Rock strength significantly influences fragmentation and runout characteristics:medium-to-high strength rocks exhibit two-stage fragmentation(10-20 s and 55-65 s),while weak-strength rocks achieve 98%fragmentation within 20 s.Optimal kinetic energy conversion occurs in medium-strength rocks,with a maximum velocity difference of 39.3 m/s between the anterior and posterior edges.(2)The sudden change in the cross-sectional dimensions of high-strength rocks under a high spreading velocity(>60 m/s)may amplify air blast hazards.(3)Deposition patterns reveal that the spatial distribution of fragments preserves original positional order;high-strength rocks produce larger fragments(nominal fragment size increases from 0.028 of weak-strength rocks to 0.607);and centroid displacement increases from 1907 m to 2117 m with rock strength in open terrains.(4)Energy dissipation analysis shows that frictional dissipation(>60%)>collisional dissipation(~37%)>>fragmentation dissipation(<2%)in the process of rockslide runout.The rock strength induces<5%variation in partitioning of energy dissipation.展开更多
Exploring the limits of neutron binding in atomic nuclei remains a central focus of nuclear physics.However,the experimental determination of the neutron drip line is challenging because of the minuscule production cr...Exploring the limits of neutron binding in atomic nuclei remains a central focus of nuclear physics.However,the experimental determination of the neutron drip line is challenging because of the minuscule production cross sections of the most neutron-rich isotopes.We investigate the effectiveness of multi-step fragmentation for producing extremely neutron-rich nuclides at relativistic energies.We demonstrate that multi-step fragmentation dominates over single-step fragmentation in thick-target experiments and can enhance the yields of drip-line nuclei by several orders of magnitude in a realistic experiment using fragment separators.Such enhancements open new possibilities for locating the drip lines above sodium and thus significantly expand the research horizon.展开更多
Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitat...Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitats by combining niche modeling with ecological trait analysis. We conducted standardized point surveys to examine the habitat preferences of 32 bird species in Inner Mongolia, China, and quantified their habitat niche parameters using the Outlying Mean Index (OMI). Our results reveal distinct habitat preferences among species, with some thriving in intact environments while others are better adapted to fragmented areas. Grassland species showed high specialization along the fragmentation gradient, while others exhibited adaptability to varying levels of fragmentation. Using a Generalized Additive Model (GAM), we identified three key traits influencing habitat occupancy: hand-wing index, body mass, and range size. Specifically, species with medium hand-wing indices, moderate body mass, and larger range sizes were more likely to occupy heavily fragmented habitats. These findings provide empirical evidence on how habitat fragmentation affects bird species in steppe ecosystems. The study highlights the importance of functional traits in understanding avian responses to habitat fragmentation and offers a foundation for developing effective conservation strategies to preserve biodiversity in fragmented landscapes.展开更多
Percussion drilling is a promising approach for hot dry rock(HDR)fragmentation.However,understanding of HDR fragmentation mechanism under multi-dimensional percussion remains limited and hinders the corresponding dril...Percussion drilling is a promising approach for hot dry rock(HDR)fragmentation.However,understanding of HDR fragmentation mechanism under multi-dimensional percussion remains limited and hinders the corresponding drilling performance.Herein,an innovative true triaxial multi-dimensional percussion device was developed for the study of HDR fragmentation mechanism under in-situ temperature and stress conditions.Multi-dimensional percussion,involving both axial and torsional components,was applied to drilling in granite and carbonatite rocks sampled from the typical HDR target areas.Multiscale visualization techniques and a whale optimization-variational mode decomposition algorithm were employed to investigate the rock failure patterns and drilling energy characteristics.Results indicated that multi-dimensional percussion enhances brittle-ductile mixed failure in granite,characterized by transgranular,intergranular,and combined fracture patterns that promote rock cracking.In contrast,carbonatite drillhole displays enhanced brittle fragmentation and tortuous failure surface dominated by transgranular fracture pattern.Frequency-domain characteristics of penetration force signals for multidimensional percussion,especially the significant dominant frequency,amplitude,and high-frequency dissipation,indicate an increase in net energy for drilling into HDR and intensified rock fragmentation.Further,the effect of impact frequency on rock fragmentation performance was emphasized to maximize drilling efficiency.The optimal regulation schemes between axial and torsional impact frequencies are identified as 15 Hz+15 Hz for granite and 30 Hz+15 Hz for carbonatite.The reliability of the optimization approach was validated through a field test that employed a novel impactor in the geothermal well Fushen-1.展开更多
基金Supported by the Major State Basic Research Development Program of China, Program 973, Grant No. 2001CB510001
文摘AIM: Most studies on the immune effect of gp96 were focused on its enhancement of CTLs. It is interesting to know whether gp96 could influence the humoral immune response, and whether the recombinant N-terminal fragment of gp96 could substitute native gp96 to stimulate the immune system.METHODS: gp96 isolated from livers of normal mice and its N-terminal fragment (amino acid 22-355) expressed in E coli were used for immunization of BALb/c mice. Eight groups of mice received one of the following regiments subcutaneously in 100 μL phosphate buffered saline (PBS)at an interval of 3 wk. Group 1: PBS only; group 2:gp96 only; group 3: N-terminal fragment only; group 4: HBsAg only; group 5: HBsAg+gp96; group 6: HBsAg+N-terminalfragment; group 7: HBsAg+incomplete Freud's adjuvant; group 8: HBsAg+N-terminal fragment (95 ℃ heated for 30 min). Serum anti-HBsAg antibody levels were assayed by ELISA. CTL responses in splenocytes were analyzed by ELISPOT after the last vaccination.RESULTS: The average titer of serum anti-HBsAg antibodyin the mice immunized with HBsAg together with gp96 or its N-terminal fragment were much higher than those immunized with HBsAg alone detected by ELISA. The cellular immune response of the mice immunized with HBsAg together with gp96 or its N-terminal fragment was not different with those immunized with HBsAg alone measured by ELISPOT assay.CONCLUSION: gp96 or its N-terminal fragment greatly improved humoral immune response induced by HBsAg, but failed to enhance the CTL response, which demonstrated the potential of using gp96 or its N-terminal fragment as a possible adjuvant to augment humoral immune response against HBV infection.
文摘Our previous results indicated that both the secreted and the intracellular form of full length and 1-97 N-terminal fragment of IGFBP-3 induce apoptosis in PC-3 human prostate cancer cells in an IGF-dependent and independent manner. This study was undertaken to delineate possible down-stream signaling pathways that are involved in this process. Intact IGFBP-3 and its N-terminal 1-97 fragments with or without a signal propeptide were fused to YFP and expressed in PC-3 human prostate cancer cells. In some cases, the putative IGF-binding site was presented in full length IGFBP-3 and its N-terminal fragment was also mutated. Extent of apoptosis was quantified using FACS. Up-regulation of total Stat-1 and activation of phospho-Stat-1 were shown by western blot. TGF-β signal was measured by luciferase reporter assay. Results from inhibitor studies indicated that both the Caspase 8 and caspase 9 pathways are involved in IGFBP-3 (non-secreted form) which induced apoptosis in PC-3 cells. Exogenous addition of IGFBP-3 to PC-3 cells increased Stat-1 protein expression/tyrosine phosphorylation. Interestingly, results also showed that knockdown of Stat-1 by siRNA potentiated the IGFBP-3 induced apoptosis in PC-3 cells. In addition, both full-length IGFBP-3 and its 1-97 Nterminal fragments inhibited TGF-β signaling in these cells. This is the first report that compares the signal transduction pathways involved in apoptotic pathways mediated by IGFBP-3 in PC-3 human prostate cancer cells. Non-secreted form of full length IGFBP-3 and its N-terminal fragments induced apoptosis in PC-3 cells via activation of caspase 8 and caspase 9. Although, only non-secreted form of IGFBP-3 is involved in inducing apoptosis in PC-3 cells via caspase 8 and caspase 9 activation pathways but both secreted and non-secreted forms of IGFBP-3 are involved in modulating Stat-1 and TGF-β pathways to induce apoptotic actions in PC-3 cells. Non-secreted intact IGFBP-3 and its N-terminal fragments induced apoptosis in PC-3 cells via activation of caspase 8 and caspase 9 pathways. Modulation in STAT-1 and TGF-β pathways may also be important for IGFBP-3 induced apoptosis in PC-3 cells in general. These studies clearly demonstrate that secreted and non-secreted FL and 1-97 N-terminal fragments induce apoptosis in PC-3 cells by regulating different mechanistic pathways.
文摘Background Elevated N-terminal pro-brain natriuretic peptide(NT-pro-BNP)is a recognized predictor of poor prognosis in heart failure and infectious diseases.We aimed to investigate its predictive value for short-term mortality in patients with infective endocarditis(IE)complicated by sepsis.Methods A total of 416 consecutive patients diagnosed with IE and sepsis at Guangdong Provincial People's Hospital were enrolled.The patients were divided into three groups according to the tertiles of NT-pro-BNP level of the first blood collection within 24 hours after admission:<2000 pg/mL(n=138),2000-7167 pg/mL(n=140),and>7167 pg/mL(n=138).Univariate and multivariate regression analysis were used to explore the predictive value of NT-pro-BNP for short-term mortality,and the best cut-off value was determined by receiver operating characteristic(ROC)curve.Results In-hospital and 6-month death occurred in 65 and 94 patients,respectively.Higher in-hospital mortality was found in patients with higher serum NT-pro-BNP levels(9.4%vs.13.6%vs.23.9%,P=0.003).ROC curve analysis identified an optimal NT-pro-BNP cutoff level of 1357 pg/mL[area under curve(AUC):0.652,95%CI:0.588-0.717,P<0.001].Multivariate regression analysis showed that both log-transformed NT-pro-BNP(in-hospital mortality:OR:1.987,95%CI:1.045-3.778,P=0.036;6-month mortality:HR:1.714,95%CI:1.072-2.7400,P=0.025)and NT-pro-BNP>1357 pg/mL(in-hospital mortality:OR:8.059,95%CI:1.813-35.818,P=0.006;6-month mortality:HR:5.193,95%CI:1.806-14.938,P=0.002)were both independent risk factors for in-hospital and 6-month mortality.Conclusions Serum NT-pro-BNP could serve as an independent predictor of in-hospital and 6-month mortality in patients with IE complicated with sepsis.
基金supported by the Indian Council of Agricultural Research(ICAR)-Senior Research Fellowship from ICAR,India(Grant No.EDN/1/25/2015-Exam cell)ICAR-Centre for Agricultural Bioinformatics and National Institute for Plant Biotechnology,India(Grant No.1006456).
文摘Dopamine β-monooxygenase N-terminal(DOMON)domain-containing genes are present across all taxa and are critical in cell signaling and redox transport.Despite their significance,these genes remain understudied in plant species.In this study,we identified 15 DOMON genes in rice and analyzed their phylogenetic relationships,conserved motifs,and cis-regulatory elements.Phylogenetic analysis revealed distinct clustering of OsDOMON genes in rice and other monocots,compared with Arabidopsis thaliana.Promoter analysis showed a higher abundance of stress-related regulatory elements in Tetep,a well-known blast and abiotic stress-tolerant cultivar,compared with Nipponbare and HP2216.OsDOMON genes displayed differential expression under biotic stress(Magnaporthe oryzae infection)and abiotic stresses(drought,heat,and salinity)in contrasting cultivars.Tetep exhibited significantly higher expression levels of specific OsDOMON genes during early blast infection stages,particularly OsDOMON6.1 and OsDOMON9.2,suggesting their roles in cell wall fortification and reactive oxygen species signaling.Under abiotic stress,genes like OsDOMON3.3,OsDOMON8.1,and OsDOMON9.2 showed higher expression in Tetep,indicating their involvement in stress tolerance mechanisms.This study provides a foundation for future functional studies of OsDOMON genes,paving the way for developing rice cultivars resistant to biotic and abiotic stresses.
基金supported by Poongsan-KAIST Future Research Center Projectthe fund support provided by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(Grant No.2023R1A2C2005661)。
文摘This study presents a machine learning-based method for predicting fragment velocity distribution in warhead fragmentation under explosive loading condition.The fragment resultant velocities are correlated with key design parameters including casing dimensions and detonation positions.The paper details the finite element analysis for fragmentation,the characterizations of the dynamic hardening and fracture models,the generation of comprehensive datasets,and the training of the ANN model.The results show the influence of casing dimensions on fragment velocity distributions,with the tendencies indicating increased resultant velocity with reduced thickness,increased length and diameter.The model's predictive capability is demonstrated through the accurate predictions for both training and testing datasets,showing its potential for the real-time prediction of fragmentation performance.
文摘STAPHYLOCOCCAL nuclease(SNase A,EC 3.1.4.7),which hydrolyzes the phosphodiesterbond of DNA and RNA,and releases 3’-phosphate mononucleotides and dinucleotides,con-sists of 149 amino acid residues(MW=16 807)without sulfhydryl and disulfide groups.SNase A was originally derived from Staphylococcus aureus.Later the gene of the enzyme wascloned and inserted into several expression systems.Its crystal structure was detected
基金National Natural Science Foundation of China,Grant/Award Number:52374153。
文摘Rock fragmentation is an important indicator for assessing the quality of blasting operations.However,accurate prediction of rock fragmentation after blasting is challenging due to the complicated blasting parameters and rock properties.For this reason,optimized by the Bayesian optimization algorithm(BOA),four hybrid machine learning models,including random forest,adaptive boosting,gradient boosting,and extremely randomized trees,were developed in this study.A total of 102 data sets with seven input parameters(spacing-to-burden ratio,hole depth-to-burden ratio,burden-to-hole diameter ratio,stemming length-to-burden ratio,powder factor,in situ block size,and elastic modulus)and one output parameter(rock fragment mean size,X_(50))were adopted to train and validate the predictive models.The root mean square error(RMSE),the mean absolute error(MAE),and the coefficient of determination(R^(2))were used as the evaluation metrics.The evaluation results demonstrated that the hybrid models showed superior performance than the standalone models.The hybrid model consisting of gradient boosting and BOA(GBoost-BOA)achieved the best prediction results compared with the other hybrid models,with the highest R^(2)value of 0.96 and the smallest values of RMSE and MAE of 0.03 and 0.02,respectively.Furthermore,sensitivity analysis was carried out to study the effects of input variables on rock fragmentation.In situ block size(XB),elastic modulus(E),and stemming length-to-burden ratio(T/B)were set as the main influencing factors.The proposed hybrid model provided a reliable prediction result and thus could be considered an alternative approach for rock fragment prediction in mining engineering.
基金financially supported by National Natural Science Foundations of China(No.31471615)Scientific Research Start-up Fund for Introduced Talents of Anhui Polytechnic University(2022YOO068)Natural Science Research Project of Colleges and Universities in Anhui Province(Grant 2022AH050971).
文摘Phospholipase A1(PLA1)is a kind of specific phospholipid hydrolase widely used in food,medical,textile.However,limitations in its expression and enzymatic activity have prompted the investigation of the phospholipase-assisting protein PlaS.In this study,we elucidate the role of PlaS in enhancing the expression and activity of PlaA1 through N-terminal truncation.Our research demonstrates that truncating the N-terminal region of PlaS effectively overcomes its inhibitory effect on host cells,resulting in improved cell growth and increased protein solubility of the protein.The yeast two-hybrid assay confirms the interaction between PlaA1 and N-terminal truncated PlaS(ΔN27 PlaS),highlighting their binding capabilities.Furthermore,in vitro studies using Biacore analysis reveal a concentration-dependent and specific binding between PlaA1 andΔN27 PlaS,exhibiting high affinity.Molecular docking analysis provides insights into the hydrogen bond interactions betweenΔN27 PlaS and PlaA1,identifying key amino acid residues crucial for their binding.Finally,the enzyme activity of PLA1 was boost to 8.4 U/mL by orthogonal test.Study significantly contributes to the understanding of the interaction mechanism between PlaS and PlaA1,offering potential strategies for enhancing PlaA1 activity through protein engineering approaches.
基金supported by National Natural Science Foundation of China (No.U23A20597)National Major Science and Technology Project of China (No.2024ZD1003803)+1 种基金Chongqing Science Fund for Distinguished Young Scholars of Chongqing Municipality (No.CSTB2022NSCQ-JQX0028)Natural Science Foundation of Chongqing (No.CSTB2024NSCQ-MSX0503)。
文摘In the application of high-pressure water jet assisted breaking of deep underground rock engineering,the influence mechanism of rock temperature on the rock fragmentation process under jet action is still unclear.Therefore,the fluid evolution characteristics and rock fracture behavior during jet impingement were studied.The results indicate that the breaking process of high-temperature rock by jet impact can be divided into four stages:initial fluid-solid contact stage,intense thermal exchange stage,perforation and fracturing stage,and crack propagation and penetration stage.With the increase of rock temperature,the jet reflection angles and the time required for complete cooling of the impact surface significantly decrease,while the number of cracks and crack propagation rate significantly increase,and the rock breaking critical time is shortened by up to 34.5%.Based on numerical simulation results,it was found that the center temperature of granite at 400℃ rapidly decreased from 390 to 260℃ within 0.7 s under jet impact.In addition,a critical temperature and critical heat flux prediction model considering the staged breaking of hot rocks was established.These findings provide valuable insights to guide the water jet technology assisted deep ground hot rock excavation project.
文摘This paper proposes an efficient strategy for resource utilization in Elastic Optical Networks (EONs) to minimize spectrum fragmentation and reduce connection blocking probability during Routing and Spectrum Allocation (RSA). The proposed method, Dynamic Threshold-Based Routing and Spectrum Allocation with Fragmentation Awareness (DT-RSAF), integrates rerouting and spectrum defragmentation as needed. By leveraging Yen’s shortest path algorithm, DT-RSAF enhances resource utilization while ensuring improved service continuity. A dynamic threshold mechanism enables the algorithm to adapt to varying network conditions, while its fragmentation awareness effectively mitigates spectrum fragmentation. Simulation results on NSFNET and COST 239 topologies demonstrate that DT-RSAF significantly outperforms methods such as K-Shortest Path Routing and Spectrum Allocation (KSP-RSA), Load Balanced and Fragmentation-Aware (LBFA), and the Invasive Weed Optimization-based RSA (IWO-RSA). Under heavy traffic, DT-RSAF reduces the blocking probability by up to 15% and achieves lower Bandwidth Fragmentation Ratios (BFR), ranging from 74% to 75%, compared to 77% - 80% for KSP-RSA, 75% - 77% for LBFA, and approximately 76% for IWO-RSA. DT-RSAF also demonstrated reasonable computation times compared to KSP-RSA, LBFA, and IWO-RSA. On a small-sized network, its computation time was 8710 times faster than that of Integer Linear Programming (ILP) on the same network topology. Additionally, it achieved a similar execution time to LBFA and outperformed IWO-RSA in terms of efficiency. These results highlight DT-RSAF’s capability to maintain large contiguous frequency blocks, making it highly effective for accommodating high-bandwidth requests in EONs while maintaining reasonable execution times.
基金supported by grants from the National Key R&D Program of China(2022YFC2702700)Natural Science Foundation of Hunan Province(2024JJ6725 and 2022JJ40657)+1 种基金Hunan Provincial Grant for Innovative Province Construction(2019SK4012)the Reproductive and Genetic Hospital of CITIC-Xiangya Foundation(YNXM-202003).
文摘Recent studies have shown that shorter periods of ejaculatory abstinence may enhance certain sperm parameters,but the molecular mechanisms underlying these improvements are still unclear.This study explored whether reduced abstinence periods could improve semen quality,particularly for use in assisted reproductive technologies(ART).We analyzed semen samples from men with normal sperm counts(n=101)and those with low sperm motility or concentration(n=53)after 3-7 days of abstinence and then after 1-3h of abstinence,obtained from the Reproductive&Genetic Hospital of CITIC-Xiangya(Changsha,China).Physiological and biochemical sperm parameters were evaluated,and the dynamics of transfer RNA(tRNA)-derived fragments(tRFs)were analyzed using deep RNA sequencing in five consecutive samples from men with normal sperm counts.Our results revealed significant improvement in sperm motility and a decrease in the DNA fragmentation index after the 1-to 3-h abstinence period.Additionally,we identified 245 differentially expressed tRFs,and the mitogen-activated protein kinase(MAPK)signaling pathway was the most enriched.Further investigations showed significant changes in tRF-Lys-TTT and its target gene mitogen-activated protein kinase kinase 2(MAP2K2),which indicates a role of tRFs in improving sperm function.These findings provide new insights into how shorter abstinence periods influence sperm quality and suggest that tRFs may serve as biomarkers for male fertility.This research highlights the potential for optimizingART protocols and improving reproductive outcomes through molecular approaches that target sperm function.
文摘This review examines the processes of laser heating,melting,evaporation,fragmentation,and breakdown of metal nanoparticles,as well as the dependences and values of the threshold laser parameters that initiate these processes.Literature results are analyzed from experimental studies of these processes with gold,silver,and other nanoparticles,including laser surface melting and evaporation of nanoparticles and Coulomb fragmentation of nanoparticles by ultrashort laser pulses.A theoretical model and description of the thermal mechanisms of mentioned processes with metal(solid)nanoparticles in a liquid(solid)medium,initiated by the action of laser pulses with the threshold fluences,are presented.Comparison of the obtained results with experimental data confirms the accuracy of the model and makes it possible to use them to evaluate the parameters of laser thermal processing of nanoparticles.Applications of the processes include the laser melting,reshaping,and fragmentation of nanoparticles,the formation of nanostructures and nanonetworks,the laser processing of nanoparticles located on substrates,and their cladding on surfaces in various laser nanotechnologies.The use of laser ignition,combustion,and incandescence of nanoparticles is discussed,as is the use of nanoparticle-triggered laser breakdown for spectroscopy.These laser processes are used in photothermal nanotechnologies,nanoenergy,laser processing of nanoparticles,nonlinear optical devices,high-temperature material science,etc.In general,this review presents a modern picture of the state of laser technology and high-temperature processes with nanoparticles and their applications,being focused on the latest publications with an emphasis on recent results from 2021-2024.
基金supported by the National Natural Science Foundation of China(Grant No.12474159)the Fundamental Research Funds for the Central University,Sun Yat-sen University(Grant No.24qnpy119)the China Postdoctoral Science Foundation(Grant No.2024T171067)。
文摘We investigate distinct non-Hermitian skin effects(NHSEs)in real and Fock spaces induced by the interplay between the Hilbert space fragmentation and multiple non-Hermitian pumping channels.Using an extended Hatano–Nelson model with next-nearest neighbor hopping and strong interaction as an example,we found that two fermions loaded in the lattice exhibit different real-space NHSE depending on the Hilbert space fragments to which they belong.Moreover,in the high-energy sector resulting from fragmentation,the two-particle-bound states form a one-dimensional lattice in Fock space,producing a Fock-space NHSE.At half-filling,richer patterns of Fock-space skin-like localization emerge for the different fragmented energy sectors and subsectors while realspace NHSE is suppressed by many-body effects.This study extends our understanding of the interplay between NHSE and Hilbert space fragmentation and provides detailed insights into their manifestation in interacting non-Hermitian systems.
文摘Total or severe teratospermia affects the prognosis of fertility and causes serious problems for patients undergoing assisted reproduction[1].The pathophysiological mechanism of teratospermia is unclear.It has been shown that patients with sperm parameters abnormalities and abnormal morphology have a high rate of fragmentation and sperm DNA decondensation[2,3],and that sperm DNA fragmentation analysis could be used as a predictor factor of fertility potential[4].
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A2047)the General Project of the Natural Science Foundation of Sichuan Province,China(Grant No.2023NSFSC0264).
文摘Rockfall represents a significant geological hazard in mountainous regions,characterized by a sudden and unpredictable feature.The process of dynamic fragmentation and energy conversion in a rockfall event remains complex and not fully understood.This study aims to gain a further understanding of the energy transfer mechanism during rockfall impact and fragmentation by impact tests using a variety of rock-like sphere specimens.The experiments mainly focus on the quantitative correlation between fragmentation degree and influence factors,i.e.impact angle and velocity on steel and granite slabs.The analysis focuses on the energy distribution characteristics,energy dissipation mechanisms,and the energy conversion rate of the fragments during impact and fragmentation.The results show that there is a significant correlation between the energy conversion rate and the fragmentation degree.In normal impact tests,elasto-plastic deformation energy and fracture energy are found to be two primary categories of energy dissipation.The proportion of total kinetic energy after impact is inversely proportional to the initial energy.A comparative analysis between normal and inclined slab impact tests reveals that the impact angle significantly influences the energy conversion rate,which controls the fragmentation degree as well.In addition,the fragmentation degree is inversely proportional to the restitution coefficient.These findings contribute to a better understanding of the energy conversion mechanism during rockfall impact and fragmentation,providing valuable insight for the development of effective strategies to mitigate such rockfall hazards.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102480,52278543 and 51978660)Natural Science Foundation of Jiangsu Province(Grant No.BK20231489)。
文摘Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.
基金support from the National Natural Science Foundation of China(41977233,U22A20601)Student Research Training Program of Fuzhou University(S202210386061).
文摘Fragmentation is a common phenomenon in the runout process of large rockslides.Rocks have different strengths under the influence of the rock type and weathering degree,resulting in varying fragmentation characteristics.However,the limited understanding of how rock strength influences the postfragmentation kinematic characteristics of rockslides is limited.Taking a natural rockslide as an example,this paper quantitatively analyzes the runout and deposition of the rockslide using the discrete element method(DEM)and examines the impacts of the rock strength on the runout and deposition characteristics of the rockslide.The results reveal that(1)Rock strength significantly influences fragmentation and runout characteristics:medium-to-high strength rocks exhibit two-stage fragmentation(10-20 s and 55-65 s),while weak-strength rocks achieve 98%fragmentation within 20 s.Optimal kinetic energy conversion occurs in medium-strength rocks,with a maximum velocity difference of 39.3 m/s between the anterior and posterior edges.(2)The sudden change in the cross-sectional dimensions of high-strength rocks under a high spreading velocity(>60 m/s)may amplify air blast hazards.(3)Deposition patterns reveal that the spatial distribution of fragments preserves original positional order;high-strength rocks produce larger fragments(nominal fragment size increases from 0.028 of weak-strength rocks to 0.607);and centroid displacement increases from 1907 m to 2117 m with rock strength in open terrains.(4)Energy dissipation analysis shows that frictional dissipation(>60%)>collisional dissipation(~37%)>>fragmentation dissipation(<2%)in the process of rockslide runout.The rock strength induces<5%variation in partitioning of energy dissipation.
基金supported by the National Natural Science Foundation of China(Nos.12325506,11961141004,12335009,12175009).
文摘Exploring the limits of neutron binding in atomic nuclei remains a central focus of nuclear physics.However,the experimental determination of the neutron drip line is challenging because of the minuscule production cross sections of the most neutron-rich isotopes.We investigate the effectiveness of multi-step fragmentation for producing extremely neutron-rich nuclides at relativistic energies.We demonstrate that multi-step fragmentation dominates over single-step fragmentation in thick-target experiments and can enhance the yields of drip-line nuclei by several orders of magnitude in a realistic experiment using fragment separators.Such enhancements open new possibilities for locating the drip lines above sodium and thus significantly expand the research horizon.
基金supported by the National Natural Science Foundation of China(No.32201304)the Fundamental Research Funds for the Central Universities(No.2412022QD026).
文摘Habitat fragmentation poses a significant threat to bird communities, especially those in open and semi-open ecosystems such as steppes. This study investigates how steppe birds adapt to and utilize fragmented habitats by combining niche modeling with ecological trait analysis. We conducted standardized point surveys to examine the habitat preferences of 32 bird species in Inner Mongolia, China, and quantified their habitat niche parameters using the Outlying Mean Index (OMI). Our results reveal distinct habitat preferences among species, with some thriving in intact environments while others are better adapted to fragmented areas. Grassland species showed high specialization along the fragmentation gradient, while others exhibited adaptability to varying levels of fragmentation. Using a Generalized Additive Model (GAM), we identified three key traits influencing habitat occupancy: hand-wing index, body mass, and range size. Specifically, species with medium hand-wing indices, moderate body mass, and larger range sizes were more likely to occupy heavily fragmented habitats. These findings provide empirical evidence on how habitat fragmentation affects bird species in steppe ecosystems. The study highlights the importance of functional traits in understanding avian responses to habitat fragmentation and offers a foundation for developing effective conservation strategies to preserve biodiversity in fragmented landscapes.
基金supported by the Major Program of National Natural Science Foundation of China(No.52192624)the Innovative Research Group Project of National Natural Science Foundation of China(No.52421002)+3 种基金Major Science and Technology Project of Yunnan Province(No.202302AF080001)NSFC Key International(Regional)Cooperative Research Projects(No.52020105001)General Program of National Natural Science Foundation of China(Nos.52204019 and 52274016)the Foundation of State Key Laboratory of Petroleum Resources and Prospecting(No.PRE/DX-2402)。
文摘Percussion drilling is a promising approach for hot dry rock(HDR)fragmentation.However,understanding of HDR fragmentation mechanism under multi-dimensional percussion remains limited and hinders the corresponding drilling performance.Herein,an innovative true triaxial multi-dimensional percussion device was developed for the study of HDR fragmentation mechanism under in-situ temperature and stress conditions.Multi-dimensional percussion,involving both axial and torsional components,was applied to drilling in granite and carbonatite rocks sampled from the typical HDR target areas.Multiscale visualization techniques and a whale optimization-variational mode decomposition algorithm were employed to investigate the rock failure patterns and drilling energy characteristics.Results indicated that multi-dimensional percussion enhances brittle-ductile mixed failure in granite,characterized by transgranular,intergranular,and combined fracture patterns that promote rock cracking.In contrast,carbonatite drillhole displays enhanced brittle fragmentation and tortuous failure surface dominated by transgranular fracture pattern.Frequency-domain characteristics of penetration force signals for multidimensional percussion,especially the significant dominant frequency,amplitude,and high-frequency dissipation,indicate an increase in net energy for drilling into HDR and intensified rock fragmentation.Further,the effect of impact frequency on rock fragmentation performance was emphasized to maximize drilling efficiency.The optimal regulation schemes between axial and torsional impact frequencies are identified as 15 Hz+15 Hz for granite and 30 Hz+15 Hz for carbonatite.The reliability of the optimization approach was validated through a field test that employed a novel impactor in the geothermal well Fushen-1.
