A phase-field model including magnetic field induced dendrite fragmentation was established and applied to the cases with different initial crystal nuclear positions for AA5754 aluminum alloy electromagnetic laser bea...A phase-field model including magnetic field induced dendrite fragmentation was established and applied to the cases with different initial crystal nuclear positions for AA5754 aluminum alloy electromagnetic laser beam welding.Compare the calculated results that include dendrite fragmentation caused by the thermal electromagnetic Lorentz force with the results that consider only the thermal electromagnetic Lorentz force,without fragmentation,at the characteristic time instants.Both in the early and late stages,the small fragmentation at the dendrite tip promotes the number of higher-order branches and their growth,especially in the direction perpendicular to the solidification.The later stage fragmentation has the possibility of breaking one grain into several,which verifies the possibility of grain refinement caused by dendrite fragmentation.The fracture surface caused by fragmentation also makes more solid-liquid interfaces and their growth.In addition,the cases with different initial nuclear positions were compared.The grain growth in the low-temperature zone can be inhibited by the equiaxed grains'fragmentation at the high-temperature area(179.8μm^(2) and 14.7% start at the center,115.4μm^(2) and 9.4% start at the high-temperature corner,134.3μm^(2) and 10.9%start at the low-temperature corner),which is another kind of grain refinement by the dendrite fragmentation.This kind of inhibition effect on grain growth in the low-temperature region will be enhanced with the increasing time interval between the two crystal nuclei’appearance(179.8μm^(2) and 14.7%when virtual grains appear at t=4.3803 s and t=4.3803 s,134.3μm^(2) and 10.9%at t=4.0977 s and t=3.9564 s,and 115.4μm^(2) and 9.4%at t=3.8151 s and t=3.5325 s).展开更多
The global mining industry,particularly deep high-stress hard-rock mining,confronts prominent challenges of massive energy consumption and low crushing/grinding efficiency.Optimized blasting,as an alternative to grind...The global mining industry,particularly deep high-stress hard-rock mining,confronts prominent challenges of massive energy consumption and low crushing/grinding efficiency.Optimized blasting,as an alternative to grinding,effectively reduces energy usage and improves transportation efficiency.Despite extensive research on the effects of confining stress to cut blasting,studies focusing on fragmentation characteristics of deep confined blasting remain scarce.This study integrates theoretical analysis,similarity model tests,and SPH-FEM simulations to investigate fragmentation size distribution and energy dissipation under varying confining stresses.Results show that the Swebrec(SWE)function achieves superior fitting to fragmentation data(goodness-offit>0.95).With increasing confining stress,the fractal dimension of specimens increases(ranging from 2.16 to 2.42 in model tests),while fragmentation energy decreases—55.23% lower under high confining stress than no confining stress in tests,and 50.61%lower at 40 MPa than 0 MPa in simulations.The ratio of fragmentation energy to blasting energy is 2%-10%.Distinct from previous studies emphasizing confining stress macroeffects on cut blasting,this work explores fragmentation distribution functions and energy under biaxial confining stress,providing valuable insights for blasting efficiency evaluation and promoting energy conservation and emission reduction in post-mineral processing.展开更多
Efficient hard-rock fragmentation remains a critical challenge in mechanized mining.This study designed an adjustable-spacing mold and conducted double cutting pick indentation tests on granite.Mechanical responses an...Efficient hard-rock fragmentation remains a critical challenge in mechanized mining.This study designed an adjustable-spacing mold and conducted double cutting pick indentation tests on granite.Mechanical responses and fragmentation characteristics under varying horizontal stresses,pick spacings,and groove depths were systematically analyzed.Unidirectional stress concentration altered the rock fragmentation modes,exhibiting a dual effect on the fragmentation process.The maximum indentation force(F_(max)),indentation hardness index(IHI),indentation modulus(IM),and indentation energy(W)initially increased and then decreased with rising horizontal stress.Appropriate spacing promoted radial crack coalescence,whereas too small a spacing(20 mm)caused repetitive re-fragmentation of rock chips,and too large a spacing(50 mm)resulted in unbroken ridges.Pre-cut grooves weakened the rock,reducing F_(max) and specific energy(SE),thus improving fragmentation efficiency,although the improvement slowed beyond a 10-mm groove depth.Based on the results and rock-mass conditioning assisted fragmentation mechanism,a“stress-structure dual control”assisted fragmentation mechanism was proposed,and a“pre-drilling unloading−alternate stopping”mining scheme was exploratorily designed.This approach creates favorable conditions for rock fragmentation by reducing stress levels and rock mass integrity in target zones,providing theoretical support and an engineering paradigm for mecheanized mining of deep resources.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
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
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
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
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
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
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
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
The formation process of blasting craters and blasting fragments is simulated using the continuumdiscontinuum element method(CDEM),providing a reference for blasting engineering design.The calculation model of the bla...The formation process of blasting craters and blasting fragments is simulated using the continuumdiscontinuum element method(CDEM),providing a reference for blasting engineering design.The calculation model of the blasting funnel is established,and the formation and fragmentation effect of the blasting crater under different explosive burial depths and different explosive package masses are numerically simulated.The propagation law of the explosion stress wave and the formation mechanism of the blasting crater are studied,and the relationship between the rock-crushing effect and blasting design parameters is quantitatively evaluated.Comparing the results of numerical simulation with the results of field tests and theoretical calculations indicated that the three are consistent,which proves the accuracy of numerical simulation.The results showed that the area of the blasting crater rises with the increase of explosive package mass and explosive burial depth.Taking the proportion of broken blocks with particle size ranging from 0.01 to 0.1 m as the research object,it can be found that the proportion of broken blocks with an explosive burial depth of 0.62 to 1.12 m is 0.45 to 0.18 times that with an explosive burial depth of 0.5 m.The proportion of broken blocks with an explosive radius of 4 to 12 cm is 1.14 to 3.29 times that with an explosive radius of 2 cm.The quantitative analysis of the blasting effect and blasting design parameters provides guidance for the design of blasting engineering.展开更多
The fragile and intricate geological environment of the Qinghai-Tibet Plateau gives rise to numerous precarious rocks along the riverbanks,posing significant risks for the upcoming construction of hydropower stations....The fragile and intricate geological environment of the Qinghai-Tibet Plateau gives rise to numerous precarious rocks along the riverbanks,posing significant risks for the upcoming construction of hydropower stations.In order to identify potential rockfalls that could endanger the Zixia hydropower project,a comprehensive analysis employing various methods was conducted to investigate the kinematic characteristics and dynamic fragmentation of such precarious rocks.Initially,UAV oblique photography and field survey were used to create a digital elevation model with a resolution of 0.25 m and map the spatial distribution of precarious rocks.Subsequently,the development characteristics of joints within rock masses were analyzed through an adit investigation.Following these preliminary steps,a transportation simulation utilizing RocPro3D,considering stochastic initiation orientation,was employed to predict the trajectories of 18 precarious rocks.As a result,two hazardous rocks that pose a direct threat to the cofferdam were identified.Finally,considering the influence of internal structure planes,a discrete element method was applied for accurately simulating the kinematic characteristics and dynamic fragmentation of these hazardous rocks.The findings underscore several key observations:(1)Slopeparallel structure planes within these hazardous rocks play a pivotal role in both the progressive failure during initiation and dynamic fragmentation during transportation;(2)Hazardous rocksⅢ-1 andⅣ-1 would pose a direct threat to the cofferdam.Notably,block b4 from hazardous rockⅢ-1,could potentially impact the cofferdam with an energy of 4598.65 kJ and an impact force of 3007.5 kN;and(3)Continuous collisions encountered during transportation facilitate the disintegration of rock masses along structure planes and generate substantial high-velocity fragments.Finally,to cope with the impact risk of collapsing blocks,a reinforced retaining wall as the mitigation measure is recommended.展开更多
Objective:To investigate whether differences exist in DNA fragmentation levels and protamine deficiency in the sperm of obese men compared to those of overweight and proven fertile,normal weight men and evaluate the a...Objective:To investigate whether differences exist in DNA fragmentation levels and protamine deficiency in the sperm of obese men compared to those of overweight and proven fertile,normal weight men and evaluate the alterations related to reproductive hormones,semen parameters and their association with body mass index(BMI).Methods:Participants in this observational study were divided into three groups based on their BMI:proven fertile,normal weight men(n=200);overweight men(n=200);and obese men(n=200).After 3 days of abstinence,seminal fluid was collected from all participants and analyzed.Blood samples were also collected on the same day for hormonal analysis.Sperm DNA fragmentation and protamine deficiency were also assessed.Results:A total of 600 men with a mean age of(34.3±7.9)2 years were included in the study.Obese males(BMI 30 kg/m or higher)exhibited significant reductions in semen volume,sperm concentration,total sperm motility percentage,progressive motility,non-progressive motility,and levels of total testosterone,follicle-stimulating hormone(FSH)and luteinizing hormone(LH)compared to overweight(BMI 25 to 29.9 kg/m2)and normal weight males(BMI 18.5 to 24.9 kg/m2)(P<0.001).Conversely,obese males showed a significant increase in prolactin level,sperm DNA fragmentation,and protamine deficiency compared to overweight and normal weight males(P<0.001).Significant negative correlations were demonstrated between BMI and sperm concentration,motility,total testosterone,FSH and LH(P<0.001),whereas prolactin,sperm DNA fragmentation and protamine deficiency were positively correlated with BMI(P<0.001).Conclusions:This study provides clear evidence that obesity contributes potentially to male infertility by inducing sperm DNA fragmentation and protamine deficiency,as well as negatively impacting reproductive hormones and semen quality.展开更多
Objective:To evaluate how DNA fragmentation index(DFI)and chromatin denaturation index(CDI)relate to semen parameters across different types of male infertility,thereby improving the understanding and assessment of sp...Objective:To evaluate how DNA fragmentation index(DFI)and chromatin denaturation index(CDI)relate to semen parameters across different types of male infertility,thereby improving the understanding and assessment of sperm quality.Methods:A prospective and descriptive cohort study was conducted over two years at the Integrated Physiology Laboratory of the University of Carthage in collaboration with the Alyssa Fertility Group,Tunisia.A total of 163 participants were classified into five groups based on their semen parameters:normozoospermia,oligozoospermia,asthenozoospermia,teratozoospermia,and oligoastheno-teratozoospermia.The normozoospermia group was selected from volunteers who had children.Semen samples were analyzed according to WHO guidelines.DFI was measured using Halosperm®and CDI was tested using aniline blue staining.Results:Both DFI and CDI were significantly higher in all infertility groups,with the oligozoospermia group showing the highest DFI and CDI.Negative correlations were found between DFI/CDI and sperm motility,concentration,and morphology in the affected groups.The normozoospermia group served as a control with the lowest DFI and CDI values.Conclusions:DFI and CDI are increasingly recognized as important biomarkers for evaluating sperm quality in cases of male infertility.Their elevated levels in patients with oligozoospermia,asthenozoospermia,teratozoospermia,and oligo-asthenoteratozoospermia underscore their potential role in not only diagnosing male infertility but also in assessing the overall reproductive outcomes for affected individuals,thus guiding more effective treatment strategies.展开更多
Electronic circular dichroism(ECD)spectrum is an important tool for as-sessing molecular chirality.Tradition-al methods,like linear response time-dependent density functional theory(LR-TDDFT),predict ECD spectra well ...Electronic circular dichroism(ECD)spectrum is an important tool for as-sessing molecular chirality.Tradition-al methods,like linear response time-dependent density functional theory(LR-TDDFT),predict ECD spectra well for small or medium-sized molecules,but struggle with large sys-tems due to high computational costs,making it a significant challenge to ac-curately and efficiently predict the ECD properties of complex systems.Within the framework of the generalized energy-based fragmentation(GEBF)method for localized excited states(ESs)calculation,we propose a combination algorithm for calculating rotatory strengths of ESs in condensed phase systems.This algorithm estimates the rotatory strength of the total system by calculating and combin-ing the transition electric and magnetic dipole moments of subsystems.We have used the GEBF method to calculate the ECD properties of chiral drug molecule derivatives,green fluo-rescent protein,and cyclodextrin derivatives,and compared their results with traditional methods or experimental data.The results show that this method can efficiently and accu-rately predict the ECD spectra of these systems.Thus,the GEBF method for ECD spectra demonstrates great potential in the chiral analysis of complex systems and chiral material design,promising to become a powerful theoretical tool in chiral chemistry.展开更多
To the Editor:Theoretically,autologous liver transplantation is posited as a treatment for patients experiencing traumatic liver rupture.How-ever,the procedural complexity and its infrequent application by the medical...To the Editor:Theoretically,autologous liver transplantation is posited as a treatment for patients experiencing traumatic liver rupture.How-ever,the procedural complexity and its infrequent application by the medical community have resulted in a lack of documented suc-cesses.This report presented the efficacious intervention in a pa-tient presenting with polytraumatic injuries involving the thoracic and abdominal regions,namely right-sided hemothorax,contusion and hematoma of the right lung,splenic rupture,lateral damage to the common bile duct,disruption of the left portal vein branch and left hepatic duct,incisions in the hepatic segments IV,V,VI,VII,and VIII,laceration of the right adrenal gland,rupture of the right hepatic venous trunk and retro-hepatic inferior vena cava(RHIVC),and pancreatic hematoma.展开更多
High levels of sperm DNA fragmentation(SDF)are associated with reduced assisted reproductive technology(ART)outcomes.Currently,SDF is not included in routine clinical assessment of male partners of infertile couples,b...High levels of sperm DNA fragmentation(SDF)are associated with reduced assisted reproductive technology(ART)outcomes.Currently,SDF is not included in routine clinical assessment of male partners of infertile couples,but the 6th edition of the World Health Organization(WHO)manual for semen analysis included the SDF assessment in the chapter on extended semen examinations.展开更多
Heavy crude oils present significant operational challenges due to their high viscosity and low API gravity.Conventional methods are often inefficient and lack scalability.This study evaluates the chemical technology ...Heavy crude oils present significant operational challenges due to their high viscosity and low API gravity.Conventional methods are often inefficient and lack scalability.This study evaluates the chemical technology known as RDV■(dynamic vasoactive reactor),a formulation characterized by threshold-based molecular reconfiguration,validated through field-proven catalytic behavior that induces molecular fragmentation of long-chain fractions(C_(17)+)into medium-chain fractions(C_(13)-C_(16))through protonation and carbocation formation.A field study in Texas was conducted on 160 barrels of heavy crude(19.6°API)treated with an ultra-low dose of 1,486 ppm of RDV■.Results obtained over a 157-day period under seasonal thermal variations showed an increase of+5.4°API,a reduction in water content to 0.1%,and complete elimination of the paraffin bed.Unlike conventional chemical treatments,RDV■operates at ultra-low concentrations and sustains its effect over extended periods without re-dosing,redefining operational paradigms in heavy crude processing.These findings validate the effectiveness of RDV■under uncontrolled field conditions and demonstrate a per-ppm efficiency 21.8 times higher than previously observed in laboratory studies.RDV■technology is established as a scalable and economically efficient solution for upgrading heavy crude oils.These results position RDV■as a transformative technology for sustainable energy operations,with direct implications for heavy crude upgrading strategies in industrial settings.展开更多
Accurate description of noncova-lent interactions in large systems is challenging due to the require-ment of high-level electron corre-lation methods.The generalized energy-based fragmentation(GEBF)approach,in conjunc...Accurate description of noncova-lent interactions in large systems is challenging due to the require-ment of high-level electron corre-lation methods.The generalized energy-based fragmentation(GEBF)approach,in conjunc-tion with the domain-based local pair natural orbital(DLPNO)method,has been applied to assess the average binding energies(ABEs)of large benzene clus-ters,specifically(C6H6)13,at the coupled cluster singles and doubles with perturbative triples correction[CCSD(T)]level and the complete basis set(CBS)limit.Utilizing GEBF-DLPNO-CCSD(T)/CBS ABEs as benchmarks,various DFT functionals were evaluated.It was found that several functionals with empirical dispersion correction,including M06-2X-D3,B3LYP-D3(BJ),and PBE-D3(BJ),provide accurate descriptions of the ABEs for(C6H6)13 clusters.Additionally,the M06-2X-D3 functional was used to calculate the ABEs and relative stabili-ties of(C6H6)n clusters for n=11,12,13,14,and 15 revealing that the(C6H6)13 cluster ex-hibits the highest relative stability.These findings align with experimental evidence suggest-ing that n=13 is one of the magic numbers for benzene clusters(C6H6)n,with n≤30.展开更多
基金supported by the Alexander von Humboldt Foundation,and Deutsche Forschungsgemeinschaft(DFG,German Research Foundation,Project No.506270597 and No.466939224).
文摘A phase-field model including magnetic field induced dendrite fragmentation was established and applied to the cases with different initial crystal nuclear positions for AA5754 aluminum alloy electromagnetic laser beam welding.Compare the calculated results that include dendrite fragmentation caused by the thermal electromagnetic Lorentz force with the results that consider only the thermal electromagnetic Lorentz force,without fragmentation,at the characteristic time instants.Both in the early and late stages,the small fragmentation at the dendrite tip promotes the number of higher-order branches and their growth,especially in the direction perpendicular to the solidification.The later stage fragmentation has the possibility of breaking one grain into several,which verifies the possibility of grain refinement caused by dendrite fragmentation.The fracture surface caused by fragmentation also makes more solid-liquid interfaces and their growth.In addition,the cases with different initial nuclear positions were compared.The grain growth in the low-temperature zone can be inhibited by the equiaxed grains'fragmentation at the high-temperature area(179.8μm^(2) and 14.7% start at the center,115.4μm^(2) and 9.4% start at the high-temperature corner,134.3μm^(2) and 10.9%start at the low-temperature corner),which is another kind of grain refinement by the dendrite fragmentation.This kind of inhibition effect on grain growth in the low-temperature region will be enhanced with the increasing time interval between the two crystal nuclei’appearance(179.8μm^(2) and 14.7%when virtual grains appear at t=4.3803 s and t=4.3803 s,134.3μm^(2) and 10.9%at t=4.0977 s and t=3.9564 s,and 115.4μm^(2) and 9.4%at t=3.8151 s and t=3.5325 s).
基金supported by the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology(No.2024yjrc71)State Key Laboratory of Precision Blasting,Jianghan University(No.PBSKL25B15)+2 种基金Foundation of Anhui Engineering Research Center of New Explosive Materials and Blasting Technology(No.AHBP2024B11)National Natural Science Foundation of China(No.52208384)Auhui Provincial Key Laboratory of Urban Rail Transit Safety and Emergency Management,Hefei University(No.2024GD003)。
文摘The global mining industry,particularly deep high-stress hard-rock mining,confronts prominent challenges of massive energy consumption and low crushing/grinding efficiency.Optimized blasting,as an alternative to grinding,effectively reduces energy usage and improves transportation efficiency.Despite extensive research on the effects of confining stress to cut blasting,studies focusing on fragmentation characteristics of deep confined blasting remain scarce.This study integrates theoretical analysis,similarity model tests,and SPH-FEM simulations to investigate fragmentation size distribution and energy dissipation under varying confining stresses.Results show that the Swebrec(SWE)function achieves superior fitting to fragmentation data(goodness-offit>0.95).With increasing confining stress,the fractal dimension of specimens increases(ranging from 2.16 to 2.42 in model tests),while fragmentation energy decreases—55.23% lower under high confining stress than no confining stress in tests,and 50.61%lower at 40 MPa than 0 MPa in simulations.The ratio of fragmentation energy to blasting energy is 2%-10%.Distinct from previous studies emphasizing confining stress macroeffects on cut blasting,this work explores fragmentation distribution functions and energy under biaxial confining stress,providing valuable insights for blasting efficiency evaluation and promoting energy conservation and emission reduction in post-mineral processing.
基金National Major Science and Technology Project for Deep Earth Exploration(No.2025ZD1008301)National Natural Science Foundation of China(No.52374153)for the financial supportthe support of the China Scholarship Council.
文摘Efficient hard-rock fragmentation remains a critical challenge in mechanized mining.This study designed an adjustable-spacing mold and conducted double cutting pick indentation tests on granite.Mechanical responses and fragmentation characteristics under varying horizontal stresses,pick spacings,and groove depths were systematically analyzed.Unidirectional stress concentration altered the rock fragmentation modes,exhibiting a dual effect on the fragmentation process.The maximum indentation force(F_(max)),indentation hardness index(IHI),indentation modulus(IM),and indentation energy(W)initially increased and then decreased with rising horizontal stress.Appropriate spacing promoted radial crack coalescence,whereas too small a spacing(20 mm)caused repetitive re-fragmentation of rock chips,and too large a spacing(50 mm)resulted in unbroken ridges.Pre-cut grooves weakened the rock,reducing F_(max) and specific energy(SE),thus improving fragmentation efficiency,although the improvement slowed beyond a 10-mm groove depth.Based on the results and rock-mass conditioning assisted fragmentation mechanism,a“stress-structure dual control”assisted fragmentation mechanism was proposed,and a“pre-drilling unloading−alternate stopping”mining scheme was exploratorily designed.This approach creates favorable conditions for rock fragmentation by reducing stress levels and rock mass integrity in target zones,providing theoretical support and an engineering paradigm for mecheanized mining of deep resources.
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.
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.
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.
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(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funded by the National Natural Science Foundation of China(Program Nos.52379128,52209162)Natural Science Foundation of Hubei Province of China(Program Nos.2023AFA048,2023AFB657)+3 种基金Hubei Provincial Key Laboratory of Construction and Management in Hydropower Engineering(Program Nos.2023KSD03,2023KSD04)Natural Science Research of Jiangsu Higher Education Institutions of China(Program No.21KJB580001)Educational Commission of Hubei Province of China(Program No.T2020005)the Young Top-Notch Talent Cultivation Program of Hubei Province.
文摘The formation process of blasting craters and blasting fragments is simulated using the continuumdiscontinuum element method(CDEM),providing a reference for blasting engineering design.The calculation model of the blasting funnel is established,and the formation and fragmentation effect of the blasting crater under different explosive burial depths and different explosive package masses are numerically simulated.The propagation law of the explosion stress wave and the formation mechanism of the blasting crater are studied,and the relationship between the rock-crushing effect and blasting design parameters is quantitatively evaluated.Comparing the results of numerical simulation with the results of field tests and theoretical calculations indicated that the three are consistent,which proves the accuracy of numerical simulation.The results showed that the area of the blasting crater rises with the increase of explosive package mass and explosive burial depth.Taking the proportion of broken blocks with particle size ranging from 0.01 to 0.1 m as the research object,it can be found that the proportion of broken blocks with an explosive burial depth of 0.62 to 1.12 m is 0.45 to 0.18 times that with an explosive burial depth of 0.5 m.The proportion of broken blocks with an explosive radius of 4 to 12 cm is 1.14 to 3.29 times that with an explosive radius of 2 cm.The quantitative analysis of the blasting effect and blasting design parameters provides guidance for the design of blasting engineering.
基金gratefully acknowledge support from the National Key Research and Development Program of China(Grant No.2022YFC3005704)the National Natural Science Foundation of China(Grant No.42277143)the Sichuan Province natural Science Foundation project(Grant No.2024NSFSC0100).
文摘The fragile and intricate geological environment of the Qinghai-Tibet Plateau gives rise to numerous precarious rocks along the riverbanks,posing significant risks for the upcoming construction of hydropower stations.In order to identify potential rockfalls that could endanger the Zixia hydropower project,a comprehensive analysis employing various methods was conducted to investigate the kinematic characteristics and dynamic fragmentation of such precarious rocks.Initially,UAV oblique photography and field survey were used to create a digital elevation model with a resolution of 0.25 m and map the spatial distribution of precarious rocks.Subsequently,the development characteristics of joints within rock masses were analyzed through an adit investigation.Following these preliminary steps,a transportation simulation utilizing RocPro3D,considering stochastic initiation orientation,was employed to predict the trajectories of 18 precarious rocks.As a result,two hazardous rocks that pose a direct threat to the cofferdam were identified.Finally,considering the influence of internal structure planes,a discrete element method was applied for accurately simulating the kinematic characteristics and dynamic fragmentation of these hazardous rocks.The findings underscore several key observations:(1)Slopeparallel structure planes within these hazardous rocks play a pivotal role in both the progressive failure during initiation and dynamic fragmentation during transportation;(2)Hazardous rocksⅢ-1 andⅣ-1 would pose a direct threat to the cofferdam.Notably,block b4 from hazardous rockⅢ-1,could potentially impact the cofferdam with an energy of 4598.65 kJ and an impact force of 3007.5 kN;and(3)Continuous collisions encountered during transportation facilitate the disintegration of rock masses along structure planes and generate substantial high-velocity fragments.Finally,to cope with the impact risk of collapsing blocks,a reinforced retaining wall as the mitigation measure is recommended.
文摘Objective:To investigate whether differences exist in DNA fragmentation levels and protamine deficiency in the sperm of obese men compared to those of overweight and proven fertile,normal weight men and evaluate the alterations related to reproductive hormones,semen parameters and their association with body mass index(BMI).Methods:Participants in this observational study were divided into three groups based on their BMI:proven fertile,normal weight men(n=200);overweight men(n=200);and obese men(n=200).After 3 days of abstinence,seminal fluid was collected from all participants and analyzed.Blood samples were also collected on the same day for hormonal analysis.Sperm DNA fragmentation and protamine deficiency were also assessed.Results:A total of 600 men with a mean age of(34.3±7.9)2 years were included in the study.Obese males(BMI 30 kg/m or higher)exhibited significant reductions in semen volume,sperm concentration,total sperm motility percentage,progressive motility,non-progressive motility,and levels of total testosterone,follicle-stimulating hormone(FSH)and luteinizing hormone(LH)compared to overweight(BMI 25 to 29.9 kg/m2)and normal weight males(BMI 18.5 to 24.9 kg/m2)(P<0.001).Conversely,obese males showed a significant increase in prolactin level,sperm DNA fragmentation,and protamine deficiency compared to overweight and normal weight males(P<0.001).Significant negative correlations were demonstrated between BMI and sperm concentration,motility,total testosterone,FSH and LH(P<0.001),whereas prolactin,sperm DNA fragmentation and protamine deficiency were positively correlated with BMI(P<0.001).Conclusions:This study provides clear evidence that obesity contributes potentially to male infertility by inducing sperm DNA fragmentation and protamine deficiency,as well as negatively impacting reproductive hormones and semen quality.
文摘Objective:To evaluate how DNA fragmentation index(DFI)and chromatin denaturation index(CDI)relate to semen parameters across different types of male infertility,thereby improving the understanding and assessment of sperm quality.Methods:A prospective and descriptive cohort study was conducted over two years at the Integrated Physiology Laboratory of the University of Carthage in collaboration with the Alyssa Fertility Group,Tunisia.A total of 163 participants were classified into five groups based on their semen parameters:normozoospermia,oligozoospermia,asthenozoospermia,teratozoospermia,and oligoastheno-teratozoospermia.The normozoospermia group was selected from volunteers who had children.Semen samples were analyzed according to WHO guidelines.DFI was measured using Halosperm®and CDI was tested using aniline blue staining.Results:Both DFI and CDI were significantly higher in all infertility groups,with the oligozoospermia group showing the highest DFI and CDI.Negative correlations were found between DFI/CDI and sperm motility,concentration,and morphology in the affected groups.The normozoospermia group served as a control with the lowest DFI and CDI values.Conclusions:DFI and CDI are increasingly recognized as important biomarkers for evaluating sperm quality in cases of male infertility.Their elevated levels in patients with oligozoospermia,asthenozoospermia,teratozoospermia,and oligo-asthenoteratozoospermia underscore their potential role in not only diagnosing male infertility but also in assessing the overall reproductive outcomes for affected individuals,thus guiding more effective treatment strategies.
基金supported by the National Natural Science Foundation of China(No.22273038 and No.22033004).
文摘Electronic circular dichroism(ECD)spectrum is an important tool for as-sessing molecular chirality.Tradition-al methods,like linear response time-dependent density functional theory(LR-TDDFT),predict ECD spectra well for small or medium-sized molecules,but struggle with large sys-tems due to high computational costs,making it a significant challenge to ac-curately and efficiently predict the ECD properties of complex systems.Within the framework of the generalized energy-based fragmentation(GEBF)method for localized excited states(ESs)calculation,we propose a combination algorithm for calculating rotatory strengths of ESs in condensed phase systems.This algorithm estimates the rotatory strength of the total system by calculating and combin-ing the transition electric and magnetic dipole moments of subsystems.We have used the GEBF method to calculate the ECD properties of chiral drug molecule derivatives,green fluo-rescent protein,and cyclodextrin derivatives,and compared their results with traditional methods or experimental data.The results show that this method can efficiently and accu-rately predict the ECD spectra of these systems.Thus,the GEBF method for ECD spectra demonstrates great potential in the chiral analysis of complex systems and chiral material design,promising to become a powerful theoretical tool in chiral chemistry.
基金supported by a grant from the Climbing Project for Medical Talent of Zhongnan Hospital,Wuhan University(PDJH202215).
文摘To the Editor:Theoretically,autologous liver transplantation is posited as a treatment for patients experiencing traumatic liver rupture.How-ever,the procedural complexity and its infrequent application by the medical community have resulted in a lack of documented suc-cesses.This report presented the efficacious intervention in a pa-tient presenting with polytraumatic injuries involving the thoracic and abdominal regions,namely right-sided hemothorax,contusion and hematoma of the right lung,splenic rupture,lateral damage to the common bile duct,disruption of the left portal vein branch and left hepatic duct,incisions in the hepatic segments IV,V,VI,VII,and VIII,laceration of the right adrenal gland,rupture of the right hepatic venous trunk and retro-hepatic inferior vena cava(RHIVC),and pancreatic hematoma.
文摘High levels of sperm DNA fragmentation(SDF)are associated with reduced assisted reproductive technology(ART)outcomes.Currently,SDF is not included in routine clinical assessment of male partners of infertile couples,but the 6th edition of the World Health Organization(WHO)manual for semen analysis included the SDF assessment in the chapter on extended semen examinations.
文摘Heavy crude oils present significant operational challenges due to their high viscosity and low API gravity.Conventional methods are often inefficient and lack scalability.This study evaluates the chemical technology known as RDV■(dynamic vasoactive reactor),a formulation characterized by threshold-based molecular reconfiguration,validated through field-proven catalytic behavior that induces molecular fragmentation of long-chain fractions(C_(17)+)into medium-chain fractions(C_(13)-C_(16))through protonation and carbocation formation.A field study in Texas was conducted on 160 barrels of heavy crude(19.6°API)treated with an ultra-low dose of 1,486 ppm of RDV■.Results obtained over a 157-day period under seasonal thermal variations showed an increase of+5.4°API,a reduction in water content to 0.1%,and complete elimination of the paraffin bed.Unlike conventional chemical treatments,RDV■operates at ultra-low concentrations and sustains its effect over extended periods without re-dosing,redefining operational paradigms in heavy crude processing.These findings validate the effectiveness of RDV■under uncontrolled field conditions and demonstrate a per-ppm efficiency 21.8 times higher than previously observed in laboratory studies.RDV■technology is established as a scalable and economically efficient solution for upgrading heavy crude oils.These results position RDV■as a transformative technology for sustainable energy operations,with direct implications for heavy crude upgrading strategies in industrial settings.
基金supported by the National Key R&D Program of China(No.2023YFB3712504)the National Natural Science Foundation of China(Nos.22273038,22073043,and 22033004)。
文摘Accurate description of noncova-lent interactions in large systems is challenging due to the require-ment of high-level electron corre-lation methods.The generalized energy-based fragmentation(GEBF)approach,in conjunc-tion with the domain-based local pair natural orbital(DLPNO)method,has been applied to assess the average binding energies(ABEs)of large benzene clus-ters,specifically(C6H6)13,at the coupled cluster singles and doubles with perturbative triples correction[CCSD(T)]level and the complete basis set(CBS)limit.Utilizing GEBF-DLPNO-CCSD(T)/CBS ABEs as benchmarks,various DFT functionals were evaluated.It was found that several functionals with empirical dispersion correction,including M06-2X-D3,B3LYP-D3(BJ),and PBE-D3(BJ),provide accurate descriptions of the ABEs for(C6H6)13 clusters.Additionally,the M06-2X-D3 functional was used to calculate the ABEs and relative stabili-ties of(C6H6)n clusters for n=11,12,13,14,and 15 revealing that the(C6H6)13 cluster ex-hibits the highest relative stability.These findings align with experimental evidence suggest-ing that n=13 is one of the magic numbers for benzene clusters(C6H6)n,with n≤30.
