The distinct element method(DEM)has been used successfully for the dynamic analysis of rigid block sys- tems.One of many difficulties associated with DEM is modeling of damping.In this paper,new procedures are propose...The distinct element method(DEM)has been used successfully for the dynamic analysis of rigid block sys- tems.One of many difficulties associated with DEM is modeling of damping.In this paper,new procedures are proposed for the damping modeling and its numerical implementation in distinct element analysis of rigid muhi-block systems.The stiff- ness proportional damping is constructed for the prescribed damping ratio,based on the non-zero fundamental frequency ef- fective during the time interval while the boundary conditions remain essentially constant.At this time interval,the funda- mental frequency can be estimated without complete eigenvalue analysis.The damping coefficients will vary while the damp- ing ratio remains the same throughout the entire analysis.A new numerical procedure is developed to prevent unnecessary energy loss that can occur during the separation phases.These procedures were implemented in the development of the dis- tinet element method for the dynamic analyses of piled multi-block systems.The analysis results |or the single-block and two-block systems were in a good agreement with the analytic predictions.Applications to the seismic analyses of piled four- block systems revealed that the new procedures can make a significant difference and may lead to much-improved results.展开更多
Last year, the State Council issued the Several Opinions on Further Strengthening the Management of Urban Planning. The guideline on urban planning has sparked heated debate among Internet users over opening up gated ...Last year, the State Council issued the Several Opinions on Further Strengthening the Management of Urban Planning. The guideline on urban planning has sparked heated debate among Internet users over opening up gated residential communities to public road system. This paper, based on the analysis of the background and contents of block system reform, explored the problems of the implementation of the block system reform and the impact of the block system reform on the real estate in China from 3 aspects, the selling points of the high-end communities, future property management and the community elderly care model.展开更多
In February 2016, the Central Committee of the Communist Party of China and the State Council of China issued the "Several Opinions of the CPC Central Committee and the State Council on Further Strengthening the ...In February 2016, the Central Committee of the Communist Party of China and the State Council of China issued the "Several Opinions of the CPC Central Committee and the State Council on Further Strengthening the Management of Urban Planning and Construction", stating that, in principle, closed residential areas will no longer be constructed and will be replaced by the promotion of the block system. This change in policy has aroused a great deal of controversy in various circles of society in China. In 2017, Chengdu, the capital city of Sichuan province, made an innovative attempt to implement "small block regulations." In 2018, the first "block system" public rental housing district appeared in Beijing, the capital of China. These innovative practices have promoted the pace of block system reform in China, but in general, the implementation of block system reform is difficult. From the perspective of public opinion, it seems that many citizens misunderstand the block system. This may be due to the complex interactions among community environmental management, public security, privacy, and other factors where individual interests and public interests meet. This article, from the perspective of the protection of civil rights, analyses the advantages and disadvantages of the block system at the value level, distinguishes the differences between the block systems of China, the UK and the US and then puts forward the theory that the block system reforms for newly built and existing residences are different and should be implemented independently. Concerning the key point of the block system reforms, the "greater difficulty in the implementation of the block system reform in the existing residential quarters" is the proposal to expropriate the commonly owned internal roads and appropriately compensate the residents. Finally, to cope with the core issues effectively, this article advocates gradual implementation of the block system reforms in China, including legislation, policy transformation, cultural construction, and pilot trials to promote the success of the implementation.展开更多
Mobile block system is a new type of block technology based on the theory of interval block. This article focuses on the analysis of safety key points, the efficient use of emergency time, the maximum efficiency of mo...Mobile block system is a new type of block technology based on the theory of interval block. This article focuses on the analysis of safety key points, the efficient use of emergency time, the maximum efficiency of mobilizers, to reduce the loss of emergency incidents and casualties.展开更多
The development direction of railways is toward the improvement of capacity and service quality, where the service quality includes safety, schedule, high speed, and comfort. In light of the existing cellular automato...The development direction of railways is toward the improvement of capacity and service quality, where the service quality includes safety, schedule, high speed, and comfort. In light of the existing cellular automaton models, in this paper, we develop a model to analyze the mixed running processes of trains with maximal speeds of 500 km/h and 350 km/h respectively in the moving block system. In the proposed model, we establish some sound rules to control the running processes of a train, where the rules include the departure rules in the intermediate stations, the overtaking rules, and the conditions of speed limitation for a train stopping at a station or passing through a station. With the consideration of the mixed ratio and the distance between two adjacent stations, the properties of the train traffic flow （including capacity and average speed） are simulated. The numerical results show that the interactions among different trains will affect the capacity, and a proper increase of the spatial distance between two adjacent stations can enhance the capacity and the average speed under the moving block.展开更多
Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic re...Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic resin and n-octanol were used to synthesize the main agent SCA-2.Hexamethylenetetramine and vinyl carbonate were selected to prepare the curing agent YGA-1,which was then compounded with SCA-2 to develop a sand fixation and water plugging system.Firstly,single-factor experiments were conducted to determine the optimal concentrations of SCA-2 and YGA-1,subsequently,the system’s sand fixation and water blocking performance were evaluated.Finally,a pilot test was carried out in the mining site.Experimental results showed that the optimal formula composition of the system was 10%SCA-2+5%YGA-1.The gelation time of the system was 180 minutes and the viscosity after gelation could reach 108.4 mPa·s.When the dosage of the drug system was 0.6 PV,the sand production rate remained below 0.08%.Dual-tube parallel experiments showed that the sand fixation and water plugging system had a water flow channel plugging rate of 87.5%,while the oil flow channel plugging rate was only 11.3%,indicating minimal damage to the oil-bearing reservoir.The field test showed that after the measures taken in Well M of X oilfield,the sand free oil recovery period exceeded 360 days,the water content decreased by 5.0%and the cumulative oil production increased by 7092 m^(3).This study provides new ideas for efficient development of loose sandstone reservoirs.展开更多
Nanoscale drug delivery systems(nano-DDSs)have attracted intense interest in tumor chemotherapy in the last decades,to improve antitumor efficacy and minimize toxic and side effects.As a versatile supramolecular build...Nanoscale drug delivery systems(nano-DDSs)have attracted intense interest in tumor chemotherapy in the last decades,to improve antitumor efficacy and minimize toxic and side effects.As a versatile supramolecular building block,cyclodextrins(CDs)have been widely used in the fabrication of the smart nano-DDSs.Besides their multifunctionality,which makes them versatile core in the star(co)polymers for micellar nanomedicines,specific host-vip inclusion complexation via their hydrophobic cavities endows them diversified functions:(i)design of amphiphilic copolymers for micellar nanomedicines,(ii)supramolecular hydrogels and poly(pseudo)rotaxane nano-hydrogels as drug carriers,and(iii)recipient for direct and indirect drug-loading.In the present work,the recent progress of CDs in nano-DDSs for tumor chemotherapy was reviewed,classified by the crucial roles of CD units.Based on the structureperformance relationship,the future perspective was also proposed.展开更多
BACKGROUND Laparoscopic nephrectomy is a preferred surgical approach due to its minimally invasive nature and faster recovery times.However,effective management of postoperative pain remains a significant challenge.Se...BACKGROUND Laparoscopic nephrectomy is a preferred surgical approach due to its minimally invasive nature and faster recovery times.However,effective management of postoperative pain remains a significant challenge.Several traditional methods,including opioid-based analgesia,are commonly used but are associated with side effects such as nausea,vomiting,sedation,and delayed recovery.In recent years,the erector spinae plane block(ESPB)has gained attention as an ultrasoundguided regional anesthesia technique offering promising results in various surgical procedures by reducing opioid requirements and enhancing patient comfort.AIM To evaluate the efficacy and safety of ESPB in comparison to conventional pain management strategies in patients undergoing laparoscopic nephrectomy.METHODS Following PRISMA guidelines,we searched PubMed,EMBASE,Web of Science,and the Cochrane Register for randomized controlled trials(RCTs)comparing ESPB with control for laparoscopic nephrectomy.The Cochrane Risk of Bias tool was employed for quality assessment.The primary outcome was total patient-controlled analgesia(PCA)consumption.Secondary outcomes included hospital discharge time and the incidence of postoperative nausea and vomiting.A random-effects meta-analysis was conducted to calculate pooled mean differences(MD)and odds ratios(OR)with 95%CIs.RESULTS Nine RCTs involving a total of 643 patients(ESPB group=320;control group=323)were included in the analysis.ESPB significantly reduced PCA opioid consumption compared to controls(MD:-14.24,95%CI:-20.66 to-7.83,P<0.0001).Subgroup analysis showed reduced PCA use with ESPB vs morphine(MD:-8.78,95%CI:-15.34 to-2.22,P=0.009),and a non-significant effect compared to other analgesics(MD:-48.26,95%CI:-143.60 to 47.09).No statistically significant differences were observed in discharge time or the incidence of nausea and vomiting.CONCLUSION ESPB demonstrates the potential of reducing PCA in laparoscopic nephrectomy patients;however,its impact on secondary outcomes remains inconclusive.Large-scale RCTs are needed to confirm ESPB's benefits and explore long-term effects.展开更多
In this paper,we present a necessary and sufficient condition for hyponormal block Toeplitz operators T on the vector-valued weighted Bergman space with symbolsΦ(z)=G^(*)(z)+F(z),where F(z)=∑^(N)_(i)=1 A_(i)z^(i)and...In this paper,we present a necessary and sufficient condition for hyponormal block Toeplitz operators T on the vector-valued weighted Bergman space with symbolsΦ(z)=G^(*)(z)+F(z),where F(z)=∑^(N)_(i)=1 A_(i)z^(i)and G(z)=∑^(N)_(i)=1 A_(−i)z^(i),A_(i)ae culants.展开更多
When patients initially present with atrial fibrillation along with an enlarged heart and heart failure, followed by atrioventricular block, it's essential to consider genetic factors.^([1])Genetic testing can off...When patients initially present with atrial fibrillation along with an enlarged heart and heart failure, followed by atrioventricular block, it's essential to consider genetic factors.^([1])Genetic testing can offer crucial diagnostic evidence, aiding in prognosis assessment and the adoption of appropriate treatment strategies.展开更多
The diagnostic efficacy of contemporary bioimaging technologies remains constrained by inherent limitations of conventional imaging agents,including suboptimal sensitivity,off-target biodistribution,and inherent cytot...The diagnostic efficacy of contemporary bioimaging technologies remains constrained by inherent limitations of conventional imaging agents,including suboptimal sensitivity,off-target biodistribution,and inherent cytotoxicity.These limitations have catalyzed the development of intelligent stimuli-responsive block copolymers-based bioimaging agents,which was engineered to dynamically respond to endogenous biochemical cues(e.g.,p H gradients,redox potential,enzyme activity,hypoxia environment) or exogenous physical triggers(e.g.,photoirradiation,thermal gradients,ultrasound(US)/magnetic stimuli).Through spatiotemporally controlled structural transformations,stimuli-responsive block copolymers enable precise contrast targeting,activatable signal amplification,and theranostic integration,thereby substantially enhancing signal-to-noise ratios of bioimaging and diagnostic specificity.Hence,this mini-review systematically examines molecular engineering principles for designing p H-,redox-,enzyme-,light-,thermo-,and US/magnetic-responsive polymers,with emphasis on structure-property relationships governing imaging performance modulation.Furthermore,we critically analyze emerging strategies for optical imaging,US synergies,and magnetic resonance imaging(MRI).Multimodal bioimaging has also been elaborated,which could overcome the inherent trade-offs between resolution,penetration depth,and functional specificity in single-modal approaches.By elucidating mechanistic insights and translational challenges,this mini-review aims to establish a design framework of stimuli-responsive block copolymersbased for high fidelity bioimaging agents and accelerate their clinical translation in precise diagnosis and therapy.展开更多
Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford prod...Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.展开更多
This paper presents a novel artificial intelligence(AI)-assisted two-stage method for optimising rock slope stability by integrating advanced 3D modelling with rock support design,aiming at minimising risks,material u...This paper presents a novel artificial intelligence(AI)-assisted two-stage method for optimising rock slope stability by integrating advanced 3D modelling with rock support design,aiming at minimising risks,material usage,and costs.In the first stage,an extended key block analysis identifies key blocks and key block groups,accounting for progressive failure and force interactions.The second stage uses AI algorithms to optimise rockbolting design,balancing stability,cost,and material use.The most efficient algorithms include the multi-objective tree-structured Parzen estimator(MOTPE)and non-dominated sorting genetic algorithms(NSGA-II and NSGA-III).Applied to the Larvik rock slope,the optimised solution uses 18 pre-tensioned cablebolts,providing 13.2 MN of active force and achieving a factor of safety of 1.31 while reducing the average anchorage length by approximately 16%compared to traditional design.The AI-assisted approach also reduces computation time by over 90%compared to Quasi-Monte Carlo(QMC)methods,demonstrating its efficiency for small-scale civil engineering projects and large-scale mining operations.The developed tool is practical,compatible with Building Information Modelling(BIM),and ready for engineering implementation,supporting sustainable and cost-effective rock slope stabilisation.While the method is largely automated,professional judgement remains crucial for verifying ground conditions and selecting the final solution.Future work will focus on integrating data uncertainties,addressing complex block deformation mechanisms,refining optimisation objectives,and improving the performance of multi-objective optimisation for slope rockboling applications to further enhance the method's versatility.展开更多
Waste graphitization cathode carbon blocks are a type of hazardous solid waste generated during the aluminum electrolysis process,and their proper disposal is a key step in the resource utilization of discarded graphi...Waste graphitization cathode carbon blocks are a type of hazardous solid waste generated during the aluminum electrolysis process,and their proper disposal is a key step in the resource utilization of discarded graphite.This study utilizes the porous“defect advantage”of a cathode carbon block matrix to prepare silicon-doped and asphalt-coated detoxified and purified waste graphitization cathode carbon blocks for use as high-performance silicon/carbon composite anode materials.The results show that the uniformly silicondoped silicon/carbon composite material features a unique amorphous carbon-encapsulated“locked silicon”structure,which effectively addresses issues such as cathode volume expansion,excessive growth of the solid electrolyte interphase(SEI)film,and poor electrical contact between active materials.Consequently,electrochemical performance is enhanced.After assembly in a half-cell,the PSCC/10%Si@C(purified waste graphitization cathode carbon/10%Si@C)material exhibits optimal electrochemical stability,with an initial charging specific capacity of 514.5 mAh/g at 0.1 C(1 C=170 mA/g)and a capacity retention rate of 95.1%after 100 cycles.At a charge rate of 2.0 C,a specific capacity of 216.9 mAh/g is achieved.This technology provides a new pathway for the economical and high-value utilization of waste cathode carbon blocks and the development of low-cost,high-performance anode materials.展开更多
Star-shaped six-arm polymers with hexaaza[2_(6)]orthoparacyclophane core and arms of block copolymers of poly-2-ethyl-5,6-dihydrooxazine with poly-2-isopropyl-5,6-dihydrooxazine were synthesized successfully using cat...Star-shaped six-arm polymers with hexaaza[2_(6)]orthoparacyclophane core and arms of block copolymers of poly-2-ethyl-5,6-dihydrooxazine with poly-2-isopropyl-5,6-dihydrooxazine were synthesized successfully using cationic ring-opening polymerization.The ratio of blocks,the order of their attachment to the core,and arm length were varied.Conformation of synthesized stars was determined by methods of molecular hydrodynamics and optics.It has been shown that star-shaped molecules were characterized by high intramolecular density,and the arm folding increased with their lengthening.The influence of the structure of block copolymers and their molar mass on the critical micelle concentration has been established.Complexes of synthesized star-shaped block copolymers with curcumin were obtained and the efficient binding of curcumin to polymer molecules was demonstrated.The behavior of the aqueous solutions of the prepared polymer stars and their complexes with curcumin was investigated by light scattering and turbidimetry methods.The influence of the structure and molar mass of star polymers on their thermoresponsiveness and the phase separation temperatures in aqueous solutions was analyzed.A slight increase in the phase separation temperature was found on passage from polymer solutions to solutions of polymer complexes with hydrophobic curcumin.展开更多
For simulating real pasteurization treatments using hot air,hot water,radio frequency and microwave heating,a unique experimental heating block system(HBS)was developed.The stability and uniformity of sample temperatu...For simulating real pasteurization treatments using hot air,hot water,radio frequency and microwave heating,a unique experimental heating block system(HBS)was developed.The stability and uniformity of sample temperatures and heating rates in HBS were determined for studying the thermal resistance of food-borne pathogens.A computer simulation model was also developed to analyze the behavior of thermal process in HBS.The results showed that the required heating rates with various set-temperatures and holding times could be easily and precisely achieved in eight selected food materials.Thermocouple and thermal imaging data showed that the good sample heating uniformity in six cells of HBS was achieved.The real temperature-time histories obtained by radio frequency energy could be approximately done in HBS by setting a number of linear regression curves.The HBS can help in more precisely characterizing the heat resistance of pathogens in foods to further develop pasteurization processes.展开更多
With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided m...With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.展开更多
The paleocontinental margins have frequent and intensive tectonic movement and various ore forming processes. According to their tectono dynamic characteristics, the paleocontinental margins can be classified into t...The paleocontinental margins have frequent and intensive tectonic movement and various ore forming processes. According to their tectono dynamic characteristics, the paleocontinental margins can be classified into three types: the divergent, the convergent and the transformational. Each type has its specific geological geochemical processes and metallogenic system. The paper discusses the tectonic evolution and ore forming features of the North China block margins, puts forward conceptions such as complexity, variety and multi stage development of metallogenic evolution in the paleocontinental margins, and expounds five factors controlling the formation of large superlarge ore deposits in the paleocontinental margins: (1) channelway, (2) rendezvous of fluids, (3) abundance of ore source, (4) thermo dynamic anomaly, (5) long duration of structural activities.展开更多
This feature article summarizes the synthesis of novel olefin block copolymers using fast syndiospecific living homo- and copolymerization of propylene, higher 1-alkene, and norbornene with ansa-fluorenylamidodimethyl...This feature article summarizes the synthesis of novel olefin block copolymers using fast syndiospecific living homo- and copolymerization of propylene, higher 1-alkene, and norbornene with ansa-fluorenylamidodimethyltitanium- based catalyst according to the authors＇ recent results. The catalytic synthesis of monodisperse polyolefin and olefin block copolymer was also described using this living system.展开更多
To date, the high power arc plasma technology is widely used. A next generation high power arc plasma system based on building block structure is presented. The whole arc plasma inverter system is composed of 12 paral...To date, the high power arc plasma technology is widely used. A next generation high power arc plasma system based on building block structure is presented. The whole arc plasma inverter system is composed of 12 paralleled units to increase the system output capability. The hierarchical control system is adopted to improve the reliability and flexibility of the high power arc plasma inverter. To ensure the reliable turn on and off of the IGBT module in each building block unit, a special pulse drive circuit is designed by using pulse transformer. The experimental result indicates that the high power arc plasma inverter system can transfer 300 kW arc plasma energy reliably with high efficiency.展开更多
文摘The distinct element method(DEM)has been used successfully for the dynamic analysis of rigid block sys- tems.One of many difficulties associated with DEM is modeling of damping.In this paper,new procedures are proposed for the damping modeling and its numerical implementation in distinct element analysis of rigid muhi-block systems.The stiff- ness proportional damping is constructed for the prescribed damping ratio,based on the non-zero fundamental frequency ef- fective during the time interval while the boundary conditions remain essentially constant.At this time interval,the funda- mental frequency can be estimated without complete eigenvalue analysis.The damping coefficients will vary while the damp- ing ratio remains the same throughout the entire analysis.A new numerical procedure is developed to prevent unnecessary energy loss that can occur during the separation phases.These procedures were implemented in the development of the dis- tinet element method for the dynamic analyses of piled multi-block systems.The analysis results |or the single-block and two-block systems were in a good agreement with the analytic predictions.Applications to the seismic analyses of piled four- block systems revealed that the new procedures can make a significant difference and may lead to much-improved results.
文摘Last year, the State Council issued the Several Opinions on Further Strengthening the Management of Urban Planning. The guideline on urban planning has sparked heated debate among Internet users over opening up gated residential communities to public road system. This paper, based on the analysis of the background and contents of block system reform, explored the problems of the implementation of the block system reform and the impact of the block system reform on the real estate in China from 3 aspects, the selling points of the high-end communities, future property management and the community elderly care model.
文摘In February 2016, the Central Committee of the Communist Party of China and the State Council of China issued the "Several Opinions of the CPC Central Committee and the State Council on Further Strengthening the Management of Urban Planning and Construction", stating that, in principle, closed residential areas will no longer be constructed and will be replaced by the promotion of the block system. This change in policy has aroused a great deal of controversy in various circles of society in China. In 2017, Chengdu, the capital city of Sichuan province, made an innovative attempt to implement "small block regulations." In 2018, the first "block system" public rental housing district appeared in Beijing, the capital of China. These innovative practices have promoted the pace of block system reform in China, but in general, the implementation of block system reform is difficult. From the perspective of public opinion, it seems that many citizens misunderstand the block system. This may be due to the complex interactions among community environmental management, public security, privacy, and other factors where individual interests and public interests meet. This article, from the perspective of the protection of civil rights, analyses the advantages and disadvantages of the block system at the value level, distinguishes the differences between the block systems of China, the UK and the US and then puts forward the theory that the block system reforms for newly built and existing residences are different and should be implemented independently. Concerning the key point of the block system reforms, the "greater difficulty in the implementation of the block system reform in the existing residential quarters" is the proposal to expropriate the commonly owned internal roads and appropriately compensate the residents. Finally, to cope with the core issues effectively, this article advocates gradual implementation of the block system reforms in China, including legislation, policy transformation, cultural construction, and pilot trials to promote the success of the implementation.
文摘Mobile block system is a new type of block technology based on the theory of interval block. This article focuses on the analysis of safety key points, the efficient use of emergency time, the maximum efficiency of mobilizers, to reduce the loss of emergency incidents and casualties.
基金Project supported by the State Social Science Fund Project, China (Grant No. 11CJY067)the Natural Science Foundation of Gansu Province, China (Grant No. 1107RJYA070)
文摘The development direction of railways is toward the improvement of capacity and service quality, where the service quality includes safety, schedule, high speed, and comfort. In light of the existing cellular automaton models, in this paper, we develop a model to analyze the mixed running processes of trains with maximal speeds of 500 km/h and 350 km/h respectively in the moving block system. In the proposed model, we establish some sound rules to control the running processes of a train, where the rules include the departure rules in the intermediate stations, the overtaking rules, and the conditions of speed limitation for a train stopping at a station or passing through a station. With the consideration of the mixed ratio and the distance between two adjacent stations, the properties of the train traffic flow （including capacity and average speed） are simulated. The numerical results show that the interactions among different trains will affect the capacity, and a proper increase of the spatial distance between two adjacent stations can enhance the capacity and the average speed under the moving block.
文摘Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic resin and n-octanol were used to synthesize the main agent SCA-2.Hexamethylenetetramine and vinyl carbonate were selected to prepare the curing agent YGA-1,which was then compounded with SCA-2 to develop a sand fixation and water plugging system.Firstly,single-factor experiments were conducted to determine the optimal concentrations of SCA-2 and YGA-1,subsequently,the system’s sand fixation and water blocking performance were evaluated.Finally,a pilot test was carried out in the mining site.Experimental results showed that the optimal formula composition of the system was 10%SCA-2+5%YGA-1.The gelation time of the system was 180 minutes and the viscosity after gelation could reach 108.4 mPa·s.When the dosage of the drug system was 0.6 PV,the sand production rate remained below 0.08%.Dual-tube parallel experiments showed that the sand fixation and water plugging system had a water flow channel plugging rate of 87.5%,while the oil flow channel plugging rate was only 11.3%,indicating minimal damage to the oil-bearing reservoir.The field test showed that after the measures taken in Well M of X oilfield,the sand free oil recovery period exceeded 360 days,the water content decreased by 5.0%and the cumulative oil production increased by 7092 m^(3).This study provides new ideas for efficient development of loose sandstone reservoirs.
文摘Nanoscale drug delivery systems(nano-DDSs)have attracted intense interest in tumor chemotherapy in the last decades,to improve antitumor efficacy and minimize toxic and side effects.As a versatile supramolecular building block,cyclodextrins(CDs)have been widely used in the fabrication of the smart nano-DDSs.Besides their multifunctionality,which makes them versatile core in the star(co)polymers for micellar nanomedicines,specific host-vip inclusion complexation via their hydrophobic cavities endows them diversified functions:(i)design of amphiphilic copolymers for micellar nanomedicines,(ii)supramolecular hydrogels and poly(pseudo)rotaxane nano-hydrogels as drug carriers,and(iii)recipient for direct and indirect drug-loading.In the present work,the recent progress of CDs in nano-DDSs for tumor chemotherapy was reviewed,classified by the crucial roles of CD units.Based on the structureperformance relationship,the future perspective was also proposed.
文摘BACKGROUND Laparoscopic nephrectomy is a preferred surgical approach due to its minimally invasive nature and faster recovery times.However,effective management of postoperative pain remains a significant challenge.Several traditional methods,including opioid-based analgesia,are commonly used but are associated with side effects such as nausea,vomiting,sedation,and delayed recovery.In recent years,the erector spinae plane block(ESPB)has gained attention as an ultrasoundguided regional anesthesia technique offering promising results in various surgical procedures by reducing opioid requirements and enhancing patient comfort.AIM To evaluate the efficacy and safety of ESPB in comparison to conventional pain management strategies in patients undergoing laparoscopic nephrectomy.METHODS Following PRISMA guidelines,we searched PubMed,EMBASE,Web of Science,and the Cochrane Register for randomized controlled trials(RCTs)comparing ESPB with control for laparoscopic nephrectomy.The Cochrane Risk of Bias tool was employed for quality assessment.The primary outcome was total patient-controlled analgesia(PCA)consumption.Secondary outcomes included hospital discharge time and the incidence of postoperative nausea and vomiting.A random-effects meta-analysis was conducted to calculate pooled mean differences(MD)and odds ratios(OR)with 95%CIs.RESULTS Nine RCTs involving a total of 643 patients(ESPB group=320;control group=323)were included in the analysis.ESPB significantly reduced PCA opioid consumption compared to controls(MD:-14.24,95%CI:-20.66 to-7.83,P<0.0001).Subgroup analysis showed reduced PCA use with ESPB vs morphine(MD:-8.78,95%CI:-15.34 to-2.22,P=0.009),and a non-significant effect compared to other analgesics(MD:-48.26,95%CI:-143.60 to 47.09).No statistically significant differences were observed in discharge time or the incidence of nausea and vomiting.CONCLUSION ESPB demonstrates the potential of reducing PCA in laparoscopic nephrectomy patients;however,its impact on secondary outcomes remains inconclusive.Large-scale RCTs are needed to confirm ESPB's benefits and explore long-term effects.
文摘In this paper,we present a necessary and sufficient condition for hyponormal block Toeplitz operators T on the vector-valued weighted Bergman space with symbolsΦ(z)=G^(*)(z)+F(z),where F(z)=∑^(N)_(i)=1 A_(i)z^(i)and G(z)=∑^(N)_(i)=1 A_(−i)z^(i),A_(i)ae culants.
基金Military Healthcare Special Scientific Research Project(25BJZ31, awarded to SHI XM)。
文摘When patients initially present with atrial fibrillation along with an enlarged heart and heart failure, followed by atrioventricular block, it's essential to consider genetic factors.^([1])Genetic testing can offer crucial diagnostic evidence, aiding in prognosis assessment and the adoption of appropriate treatment strategies.
基金supported by the National Natural Science Foundation of China (Nos.22208218,22078196,and 22278268)the Natural Science Foundation of Shanghai (No.22ZR1460400)Collaborative Innovation Center of Fragrance Flavour and Cosmetics,and Collaborative Innovation Project of Shanghai Institute of Technology (No.XTCX2023-07)。
文摘The diagnostic efficacy of contemporary bioimaging technologies remains constrained by inherent limitations of conventional imaging agents,including suboptimal sensitivity,off-target biodistribution,and inherent cytotoxicity.These limitations have catalyzed the development of intelligent stimuli-responsive block copolymers-based bioimaging agents,which was engineered to dynamically respond to endogenous biochemical cues(e.g.,p H gradients,redox potential,enzyme activity,hypoxia environment) or exogenous physical triggers(e.g.,photoirradiation,thermal gradients,ultrasound(US)/magnetic stimuli).Through spatiotemporally controlled structural transformations,stimuli-responsive block copolymers enable precise contrast targeting,activatable signal amplification,and theranostic integration,thereby substantially enhancing signal-to-noise ratios of bioimaging and diagnostic specificity.Hence,this mini-review systematically examines molecular engineering principles for designing p H-,redox-,enzyme-,light-,thermo-,and US/magnetic-responsive polymers,with emphasis on structure-property relationships governing imaging performance modulation.Furthermore,we critically analyze emerging strategies for optical imaging,US synergies,and magnetic resonance imaging(MRI).Multimodal bioimaging has also been elaborated,which could overcome the inherent trade-offs between resolution,penetration depth,and functional specificity in single-modal approaches.By elucidating mechanistic insights and translational challenges,this mini-review aims to establish a design framework of stimuli-responsive block copolymersbased for high fidelity bioimaging agents and accelerate their clinical translation in precise diagnosis and therapy.
基金financially supported by National Key R&D Program Young Scientists Project(No.2023YFC3903100)the National Natural Science Foundation of China(No.22322503)analytical and testing assistance from the Analysis and Testing Center of HUST。
文摘Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.
基金support from Research Council of Norway via STIPINST PhD grant(Grant No.323307),Bever Control AS,and Bane NOR.
文摘This paper presents a novel artificial intelligence(AI)-assisted two-stage method for optimising rock slope stability by integrating advanced 3D modelling with rock support design,aiming at minimising risks,material usage,and costs.In the first stage,an extended key block analysis identifies key blocks and key block groups,accounting for progressive failure and force interactions.The second stage uses AI algorithms to optimise rockbolting design,balancing stability,cost,and material use.The most efficient algorithms include the multi-objective tree-structured Parzen estimator(MOTPE)and non-dominated sorting genetic algorithms(NSGA-II and NSGA-III).Applied to the Larvik rock slope,the optimised solution uses 18 pre-tensioned cablebolts,providing 13.2 MN of active force and achieving a factor of safety of 1.31 while reducing the average anchorage length by approximately 16%compared to traditional design.The AI-assisted approach also reduces computation time by over 90%compared to Quasi-Monte Carlo(QMC)methods,demonstrating its efficiency for small-scale civil engineering projects and large-scale mining operations.The developed tool is practical,compatible with Building Information Modelling(BIM),and ready for engineering implementation,supporting sustainable and cost-effective rock slope stabilisation.While the method is largely automated,professional judgement remains crucial for verifying ground conditions and selecting the final solution.Future work will focus on integrating data uncertainties,addressing complex block deformation mechanisms,refining optimisation objectives,and improving the performance of multi-objective optimisation for slope rockboling applications to further enhance the method's versatility.
基金supported by the National Natural Science Foundation of China(No.52274346).
文摘Waste graphitization cathode carbon blocks are a type of hazardous solid waste generated during the aluminum electrolysis process,and their proper disposal is a key step in the resource utilization of discarded graphite.This study utilizes the porous“defect advantage”of a cathode carbon block matrix to prepare silicon-doped and asphalt-coated detoxified and purified waste graphitization cathode carbon blocks for use as high-performance silicon/carbon composite anode materials.The results show that the uniformly silicondoped silicon/carbon composite material features a unique amorphous carbon-encapsulated“locked silicon”structure,which effectively addresses issues such as cathode volume expansion,excessive growth of the solid electrolyte interphase(SEI)film,and poor electrical contact between active materials.Consequently,electrochemical performance is enhanced.After assembly in a half-cell,the PSCC/10%Si@C(purified waste graphitization cathode carbon/10%Si@C)material exhibits optimal electrochemical stability,with an initial charging specific capacity of 514.5 mAh/g at 0.1 C(1 C=170 mA/g)and a capacity retention rate of 95.1%after 100 cycles.At a charge rate of 2.0 C,a specific capacity of 216.9 mAh/g is achieved.This technology provides a new pathway for the economical and high-value utilization of waste cathode carbon blocks and the development of low-cost,high-performance anode materials.
基金financially supported by the Russian Science Foundation(No.23-13-00205)。
文摘Star-shaped six-arm polymers with hexaaza[2_(6)]orthoparacyclophane core and arms of block copolymers of poly-2-ethyl-5,6-dihydrooxazine with poly-2-isopropyl-5,6-dihydrooxazine were synthesized successfully using cationic ring-opening polymerization.The ratio of blocks,the order of their attachment to the core,and arm length were varied.Conformation of synthesized stars was determined by methods of molecular hydrodynamics and optics.It has been shown that star-shaped molecules were characterized by high intramolecular density,and the arm folding increased with their lengthening.The influence of the structure of block copolymers and their molar mass on the critical micelle concentration has been established.Complexes of synthesized star-shaped block copolymers with curcumin were obtained and the efficient binding of curcumin to polymer molecules was demonstrated.The behavior of the aqueous solutions of the prepared polymer stars and their complexes with curcumin was investigated by light scattering and turbidimetry methods.The influence of the structure and molar mass of star polymers on their thermoresponsiveness and the phase separation temperatures in aqueous solutions was analyzed.A slight increase in the phase separation temperature was found on passage from polymer solutions to solutions of polymer complexes with hydrophobic curcumin.
基金This research was conducted in the College of Mechanical and Electronic Engineering,Northwest A&F Universitysupported by research grants from General Program of National Natural Science Foundation of China(31371853)National Key Research and Development Program of China(2016YFD0401000).
文摘For simulating real pasteurization treatments using hot air,hot water,radio frequency and microwave heating,a unique experimental heating block system(HBS)was developed.The stability and uniformity of sample temperatures and heating rates in HBS were determined for studying the thermal resistance of food-borne pathogens.A computer simulation model was also developed to analyze the behavior of thermal process in HBS.The results showed that the required heating rates with various set-temperatures and holding times could be easily and precisely achieved in eight selected food materials.Thermocouple and thermal imaging data showed that the good sample heating uniformity in six cells of HBS was achieved.The real temperature-time histories obtained by radio frequency energy could be approximately done in HBS by setting a number of linear regression curves.The HBS can help in more precisely characterizing the heat resistance of pathogens in foods to further develop pasteurization processes.
基金the Indian Institute of Technology Bombay’s Post-Doctoral Research Program, vide appointment no. AO/Admn1/33/2018 dated 10.Aug’2018 for providing funding
文摘With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.
文摘The paleocontinental margins have frequent and intensive tectonic movement and various ore forming processes. According to their tectono dynamic characteristics, the paleocontinental margins can be classified into three types: the divergent, the convergent and the transformational. Each type has its specific geological geochemical processes and metallogenic system. The paper discusses the tectonic evolution and ore forming features of the North China block margins, puts forward conceptions such as complexity, variety and multi stage development of metallogenic evolution in the paleocontinental margins, and expounds five factors controlling the formation of large superlarge ore deposits in the paleocontinental margins: (1) channelway, (2) rendezvous of fluids, (3) abundance of ore source, (4) thermo dynamic anomaly, (5) long duration of structural activities.
文摘This feature article summarizes the synthesis of novel olefin block copolymers using fast syndiospecific living homo- and copolymerization of propylene, higher 1-alkene, and norbornene with ansa-fluorenylamidodimethyltitanium- based catalyst according to the authors＇ recent results. The catalytic synthesis of monodisperse polyolefin and olefin block copolymer was also described using this living system.
基金supported by National Natural Science Foundation of China (50805051)Guangdong Provincial Science and Technology Project (2008B010400041)
文摘To date, the high power arc plasma technology is widely used. A next generation high power arc plasma system based on building block structure is presented. The whole arc plasma inverter system is composed of 12 paralleled units to increase the system output capability. The hierarchical control system is adopted to improve the reliability and flexibility of the high power arc plasma inverter. To ensure the reliable turn on and off of the IGBT module in each building block unit, a special pulse drive circuit is designed by using pulse transformer. The experimental result indicates that the high power arc plasma inverter system can transfer 300 kW arc plasma energy reliably with high efficiency.
