AIM: Gastrointestinal dysfunction is a common complication in patients with traumatic brain injury (TBI). However, the effect of traumatic brain injury on intestinal mucosa has not been studied previously. The aim of ...AIM: Gastrointestinal dysfunction is a common complication in patients with traumatic brain injury (TBI). However, the effect of traumatic brain injury on intestinal mucosa has not been studied previously. The aim of the current study was to explore the alterations of intestinal mucosa morphology and barrier function, and to determine how rapidly the impairment of gut barrier function occurs and how long it persists following traumatic brain injury.METHODS: Male Wistar rats were randomly divided into six groups (6 rats each group) including controls without brain injury and traumatic brain injury groups at hours 3,12, 24, and 72, and on day 7. The intestinal mucosa structure was detected by histopathological examination and electron microscopy. Gut barrier dysfunction was evaluated by detecting serum endotoxin and intestinal permeability. The level of serum endotoxin and intestinal permeability was measured by using chromogenic limulus amebocyte lysate and lactulose/mannitol (L/M) ratio, respectively.RESULTS: After traumatic brain injury, the histopathological alterations of gut mucosa occurred rapidly as early as 3 hours and progressed to a serious state, including shedding of epithelial cells, fracture of villi, focal ulcer, fusion of adjacent villi, dilation of central chyle duct, mucosal atrophy,and vascular dilation, congestion and edema in the villous interstitium and lamina propria. Apoptosis of epithelial cells,fracture and sparseness of microvilli, loss of tight junction between enterocytes, damage of mitochondria and endoplasm, were found by electron microscopy. The villous height, crypt depth and surface area in jejunum decreased progressively with the time of brain injury. As compared with that of control group (183.7±41.8 EU/L), serum endotoxin level was signnificantly increased at 3, 12, and 24 hours following TBI (434.8±54.9 EU/L, 324.2±61.7 EU/L and 303.3±60.2 EU/L, respectively), and peaked at 72 hours (560.5±76.2 EU/L), then declined on day 7 (306.7±62.4 EU/L,P＜0.0L). Two peaks of serum 展开更多
AIM:To study the alterations of brain-gut peptides following traumatic brain injury (TBI) and to explore the underlying significance of these peptides in the complicated gastrointestinal dysfunction.METHODS:Rat models...AIM:To study the alterations of brain-gut peptides following traumatic brain injury (TBI) and to explore the underlying significance of these peptides in the complicated gastrointestinal dysfunction.METHODS:Rat models of focal traumatic brain injury were established by impact insult method,and divided into 6 groups (6 rats each group) including control group with sham operation and TBI groups at postinjury 3,12,24,72h,and d 7.Blood and proximal jejunum samples were taken at time point of each group and gross observations of gastrointestinal pathology were recorded simultaneously.The levels of vasoactive intestinal peptide (VIP) in plasma,calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in both plasma and jejunum were measured by enzyme immunoassay (EIA). Radioimmunoassay (RIA) was used to determine the levels of VIP in jejunum.RESULTS:Gastric distension,delayed gastric emptying and intestinal dilatation with a large amount of yellowish effusion and thin edematous wall were found in TBI rats through 12h and 72h, which peaked at postinjury 72h. As compared with that of control group (247.8±29.5ng/L), plasma VIP levels were significantly decreased at postinjury 3,12 and 24h (106.7±34.1ng/L, 148.7±22.8ng/L,132.8±21.6ng/L,respectively),but significantly increased at 72h (405.0±29.8ng/L) and markedly declined on d 7 (130.7±19.3ng/L).However,Plasma levels CCK and CGRP were significantly increased through 3h and 7d following TBI (126-691% increases),with the peak at 72 h.Compared with control (VIP, 13.6±1.4ng/g;CGRP,70.6±17.7ng/g);VIP and CGRP levels in jejunum were significantly increased at 3h after TBI (VIP,35.4±5.0ng/g;CGRP,103.8±22.1ng/g),and declined gradually at 12 h and 2d h (VIP,16.5±1.8ng/g,5.5±1.4ng/g;CGRP,34.9±9.7ng/g, 18.5±7.7ng/g),but were significantly increased again at 72 h (VIP, 48.7±9.5ng/g; CGRP,142.1±24.3ng/g),then declined in various degrees on d 7 (VIP, 3.8±1.1ng/g; CGRP, 102.5±18.1ng/g).The CCK levels in jejunum were found to change in a similar trend as that in p展开更多
In the industrial process situation, principal component analysis (PCA) is ageneral method in data reconciliation. However, PCA sometime is unfeasible to nonlinear featureanalysis and limited in application to nonline...In the industrial process situation, principal component analysis (PCA) is ageneral method in data reconciliation. However, PCA sometime is unfeasible to nonlinear featureanalysis and limited in application to nonlinear industrial process. Kernel PCA (KPCA) is extensionof PCA and can be used for nonlinear feature analysis. A nonlinear data reconciliation method basedon KPCA is proposed. The basic idea of this method is that firstly original data are mapped to highdimensional feature space by nonlinear function, and PCA is implemented in the feature space. Thennonlinear feature analysis is implemented and data are reconstructed by using the kernel. The datareconciliation method based on KPCA is applied to ternary distillation column. Simulation resultsshow that this method can filter the noise in measurements of nonlinear process and reconciliateddata can represent the true information of nonlinear process.展开更多
Based on the composite modification technology of the surface of nano Silicondioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on thesurface of nano silicon dioxide. The modifi...Based on the composite modification technology of the surface of nano Silicondioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on thesurface of nano silicon dioxide. The modification mechanism and the bonding status on the surface ofnano silicon dioxide after modification were suggested via the results of the infrared spectrum,transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formedby hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxideto form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto thesurface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer throughfree radical polymerization between the double bonds on the surface of nano silicon dioxide andstyrene under the action of initiating agent. The dispersibility of nano silicon dioxide and thecontrollability of surface modification of nano silicon dioxide can be greatly improved by themodification process.展开更多
To get the influence of the randomness of longitudinal resistance of ballast bed (LRBB) on track-bridge interaction, the statistical law of LRBB was studied with existing test data and the Shapiro-Wilk test. Based on ...To get the influence of the randomness of longitudinal resistance of ballast bed (LRBB) on track-bridge interaction, the statistical law of LRBB was studied with existing test data and the Shapiro-Wilk test. Based on the principle of track-bridge interaction, a rail-sleeper-bridge-pier integrated simulation model that could consider the randomness of LRBB was established. Taking a continuous beam bridge for the heavy-haul railway as an example, the effect of the randomness of LRBB on the mechanical behavior of continuous welded rail (CWR) on bridges under typical conditions was carefully examined with a random sampling method and the simulation model. The results show that the LRBB corresponding sleeper displacement of 2 mm obeys a normal distribution. When the randomness of LRBB is considered, the amplitudes of rail expansion force, rail bending force, rail braking force and rail broken gap all follow normal distribution. As the standard deviations of the four indexes are small, which indicates the randomness of LRBB has little effect on track-bridge interaction. The distributions of the four indexes make it possible to design CWR on bridges with the limit state method.展开更多
A catalyst-free and atom-economical[4+3]cycloaddition of azadienes with C,N-cyclic azomethine imines has been developed,providing an efficient and environmentally benign access to 1,2,4-triazepines with high diastereo...A catalyst-free and atom-economical[4+3]cycloaddition of azadienes with C,N-cyclic azomethine imines has been developed,providing an efficient and environmentally benign access to 1,2,4-triazepines with high diastereoselectivities and yields.This reaction can be performed in 2-methyltetrahydrofuran under mild conditions smoothly.展开更多
The collocation method is a widely used numerical method for science and engineering problems governed by partial differential equations.This paper provides a comprehensive review of collocation methods and their appl...The collocation method is a widely used numerical method for science and engineering problems governed by partial differential equations.This paper provides a comprehensive review of collocation methods and their applications,focused on elasticity,heat conduction,electromagnetic field analysis,and fluid dynamics.The merits of the collocation method can be attributed to the need for element mesh,simple implementation,high computational efficiency,and ease in handling irregular domain problems since the collocation method is a type of node-based numerical method.Beginning with the fundamental principles of the collocation method,the discretization process in the continuous domain is elucidated,and how the collocation method approximation solutions for solving differential equations are explained.Delving into the historical development of the collocation methods,their earliest applications and key milestones are traced,thereby demonstrating their evolution within the realm of numerical computation.The mathematical foundations of collocation methods,encompassing the selection of interpolation functions,definition of weighting functions,and derivation of integration rules,are examined in detail,emphasizing their significance in comprehending the method’s effectiveness and stability.At last,the practical application of the collocation methods in engineering contexts is emphasized,including heat conduction simulations,electromagnetic coupled field analysis,and fluid dynamics simulations.These specific case studies can underscore collocation method’s broad applicability and effectiveness in addressing complex engineering challenges.In conclusion,this paper puts forward the future development trend of the collocation method through rigorous analysis and discussion,thereby facilitating further advancements in research and practical applications within these fields.展开更多
We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on t...We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on thepoint-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peakcompression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metalmicrowire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamicsimulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, arealdensities of the targets were evaluated.展开更多
AIM：To study the operativ injury,post-operative complications,the hospitalization time,the post-operative survival rate of ultrasonic aspiration hepatectomy with a domestic new type of ultrasonic surgical device in c...AIM：To study the operativ injury,post-operative complications,the hospitalization time,the post-operative survival rate of ultrasonic aspiration hepatectomy with a domestic new type of ultrasonic surgical device in comparison with that of conventional techniques of hepatectomy.METHODS:A total136patients with hepatocellular carcinoma(HCC,including 13patinents in 1991and 124consecutive patients from July1995to December2000)underwent ultrasonic aspiration in liver resection(groupT)and 179 HCCpatients received conventional hepatectomy during the corresponding period(groupC).The results of the two groups were compared statistically.RESULTS:There was no significant difference in the mean operation time between groupT(152±11min)and C(144±11min).No operation or hospital edath occurred in both groups.In groupT,the mean volumes of bleeding(463±15ml)and bolld transfusion(381±12ml)were markedly less than those in groupC(557±20ml,and507±18ml,respectively,P<0.05).The mean hospitalization time of groupT(8.9±0.6d)was markedly shorter than that of groupC(11.7d±0.6d)(P<0.05).The incidence of complications in groupTwas markedly lower than in groupC,post-operative jaundice occurred in4/136and31/179,respectively(P<0.05).liver failurein0/136and2/179,cholorrhea in0/136and6/179,hydrothoraxin21/136and39/179(P<0.05).ascices in9/136and2/179,cholrrheain0/136and6/179,hydrothorax in21/136and 39/179(P<0.05),ascices in 9/136and 54/179,respectively(P<0.05),while the 3-year survival rate of groupT(64.2%)increased markedly as compared with that of groupC(55.7%)(P<0.01).CONCLUSION:The ultrasonic aspiration hepatectomy with a domestic new type of ultrasonic surgical device could evidently reduce the operative injury and post-operative complications,shorten the hospitalization,time and prolong the survivals of HCC,patients.展开更多
Alzheimer’s disease(AD)is a complex,progressive neurodegenerative disorder.The subtle and insidious onset of its pathogenesis makes early detection of a formidable challenge in both contemporary neuroscience and clin...Alzheimer’s disease(AD)is a complex,progressive neurodegenerative disorder.The subtle and insidious onset of its pathogenesis makes early detection of a formidable challenge in both contemporary neuroscience and clinical practice.In this study,we introduce an advanced diagnostic methodology rooted in theMed-3D transfermodel and enhanced with an attention mechanism.We aim to improve the precision of AD diagnosis and facilitate its early identification.Initially,we employ a spatial normalization technique to address challenges like clarity degradation and unsaturation,which are commonly observed in imaging datasets.Subsequently,an attention mechanism is incorporated to selectively focus on the salient features within the imaging data.Building upon this foundation,we present the novelMed-3D transfermodel,designed to further elucidate and amplify the intricate features associated withADpathogenesis.Our proposedmodel has demonstrated promising results,achieving a classification accuracy of 92%.To emphasize the robustness and practicality of our approach,we introduce an adaptive‘hot-updating’auxiliary diagnostic system.This system not only enables continuous model training and optimization but also provides a dynamic platform to meet the real-time diagnostic and therapeutic demands of AD.展开更多
Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performa...Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.展开更多
This paper presents a combined method to model grain crushing effects with discrete element method.This method combines the two most commonly used concepts to model grain crushing in DEM,i.e.the replacement method and...This paper presents a combined method to model grain crushing effects with discrete element method.This method combines the two most commonly used concepts to model grain crushing in DEM,i.e.the replacement method and the agglomerate method,so that it is both accurate and efficient.The method can be easily implemented.The performance is shown by several DEM simulations of biaxial tests.Particles with different crush-abilities are modeled.DEM simulation results with and without grain crushing are compared and discussed.The change of grain size distribution due to grain crushing is also investigated.展开更多
Dear Editor,This letter proposes a process-monitoring method based on temporal feature agglomeration and enhancement,in which a novel feature extractor called contrastive feature extractor(CFE)extracts the temporal an...Dear Editor,This letter proposes a process-monitoring method based on temporal feature agglomeration and enhancement,in which a novel feature extractor called contrastive feature extractor(CFE)extracts the temporal and relational features among process parameters.Then the feature representations are enhanced by maximizing the separation among different classes while minimizing the scatter within each class.展开更多
The basie idea and method about determination of the feature line equations and how to apply them to the numerical control of the press bending of panei skins were introduced. Research indicates that it is feasible to...The basie idea and method about determination of the feature line equations and how to apply them to the numerical control of the press bending of panei skins were introduced. Research indicates that it is feasible to realize the self adapting incremental press bending by adopting the feature line equation. The feature line equation, which is based on the database of the status of practical processes, can be adjusted in time, and the forming precision can be improved. It is important to correctly select and reasonably predict the feature line equations to enhance the accuracy of the incremental press bending based on the feature line database and algorithm. The determination of the feature line equation settles necessary data foundation for further research on the database of self-adapting incremental press bending, and it supplies a new clue for the development of self-adapting incremental press bending.展开更多
PREPARATION of HMW DNA (Megabase-size) is the basis for construction of genomic library with large DNA inserts such as bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC), and for long-range ph...PREPARATION of HMW DNA (Megabase-size) is the basis for construction of genomic library with large DNA inserts such as bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC), and for long-range physical mapping. It can also be used for the macro-study of repeat sequences. Since HMW DNA during preparation is inclined to be sheared physically and digested by internal nucleases, it is very difficult to prepare the HMW DNA. Initially, plant HMW DNA was prepared by embedding protoplasts in the low melting-point (LMP) agarose; however, it had several disadvantages: (ⅰ) Culture of protoplasts was time-consuming, costly and tedious. ( ⅱ ) It was only used successfully for limited展开更多
The discharge of slaughterhouse wastewater(SWW)is increasing and its wastewater has to be treated thoroughly to avoid the eutrophication.The hybrid zeolite-based ion-exchange and sulfur autotrophic denitrification(IX-...The discharge of slaughterhouse wastewater(SWW)is increasing and its wastewater has to be treated thoroughly to avoid the eutrophication.The hybrid zeolite-based ion-exchange and sulfur autotrophic denitrification(IX-AD)process was developed to advanced treat SWW after traditional secondary biological process.Compared with traditional sulfur oxidizing denitrification(SOD),this study found that IX-AD column showed:(1)stronger ability to resist NO_(3)^(-) pollution load,(2)lower SO_(4)^(2-) productivity,and(3)higher microbial diversity and richness.Liaoning zeolites addition guaranteed not only the standard discharge of NH_(4)^(+)-N,but also the denitrification performance and effluent TN.Especially,when the ahead secondary biological treatment process run at the ultra-high load,NO_(3)-N removal efficiency for IX-AD column was still~100%,whereas only 64.2%for control SOD column.The corresponding average effluent TN concentrations for IX-AD and SOD columns were 5.89 and 65.55 mg/L,respectively.Therefore,IX-AD is a promising technology for advanced SWW treatment and should be widely researched and popularized.展开更多
Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling...Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling among inputs and outputs. In this paper, model predictive control(MPC) method based on multi-model and double layered optimization is introduced for coordinated control of USC unit running in sliding pressure mode and fixed pressure mode. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. output power, main steam temperature and main steam pressure). The step responses for the dynamic matrix control(DMC) are constructed using the three inputs by the three outputs under both pressure control mode. Piecewise models are built at selected operation points. In simulation, the output power follows load demand quickly and main steam temperature can be controlled around the setpoint closely in load tracking control. The simulation results show the effectiveness of the proposed methods.展开更多
基金the Scientific Research Foundation of the Chinese PLA Key Medical Programs during the 10th Five-Year Plan Period,No.01Z011
文摘AIM: Gastrointestinal dysfunction is a common complication in patients with traumatic brain injury (TBI). However, the effect of traumatic brain injury on intestinal mucosa has not been studied previously. The aim of the current study was to explore the alterations of intestinal mucosa morphology and barrier function, and to determine how rapidly the impairment of gut barrier function occurs and how long it persists following traumatic brain injury.METHODS: Male Wistar rats were randomly divided into six groups (6 rats each group) including controls without brain injury and traumatic brain injury groups at hours 3,12, 24, and 72, and on day 7. The intestinal mucosa structure was detected by histopathological examination and electron microscopy. Gut barrier dysfunction was evaluated by detecting serum endotoxin and intestinal permeability. The level of serum endotoxin and intestinal permeability was measured by using chromogenic limulus amebocyte lysate and lactulose/mannitol (L/M) ratio, respectively.RESULTS: After traumatic brain injury, the histopathological alterations of gut mucosa occurred rapidly as early as 3 hours and progressed to a serious state, including shedding of epithelial cells, fracture of villi, focal ulcer, fusion of adjacent villi, dilation of central chyle duct, mucosal atrophy,and vascular dilation, congestion and edema in the villous interstitium and lamina propria. Apoptosis of epithelial cells,fracture and sparseness of microvilli, loss of tight junction between enterocytes, damage of mitochondria and endoplasm, were found by electron microscopy. The villous height, crypt depth and surface area in jejunum decreased progressively with the time of brain injury. As compared with that of control group (183.7±41.8 EU/L), serum endotoxin level was signnificantly increased at 3, 12, and 24 hours following TBI (434.8±54.9 EU/L, 324.2±61.7 EU/L and 303.3±60.2 EU/L, respectively), and peaked at 72 hours (560.5±76.2 EU/L), then declined on day 7 (306.7±62.4 EU/L,P＜0.0L). Two peaks of serum
基金Supported by the Scientific Research Foundation of the Chinese PLA Key Medical Programs during the 10~(th) Five-Year Plan Period,No.01Z011
文摘AIM:To study the alterations of brain-gut peptides following traumatic brain injury (TBI) and to explore the underlying significance of these peptides in the complicated gastrointestinal dysfunction.METHODS:Rat models of focal traumatic brain injury were established by impact insult method,and divided into 6 groups (6 rats each group) including control group with sham operation and TBI groups at postinjury 3,12,24,72h,and d 7.Blood and proximal jejunum samples were taken at time point of each group and gross observations of gastrointestinal pathology were recorded simultaneously.The levels of vasoactive intestinal peptide (VIP) in plasma,calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in both plasma and jejunum were measured by enzyme immunoassay (EIA). Radioimmunoassay (RIA) was used to determine the levels of VIP in jejunum.RESULTS:Gastric distension,delayed gastric emptying and intestinal dilatation with a large amount of yellowish effusion and thin edematous wall were found in TBI rats through 12h and 72h, which peaked at postinjury 72h. As compared with that of control group (247.8±29.5ng/L), plasma VIP levels were significantly decreased at postinjury 3,12 and 24h (106.7±34.1ng/L, 148.7±22.8ng/L,132.8±21.6ng/L,respectively),but significantly increased at 72h (405.0±29.8ng/L) and markedly declined on d 7 (130.7±19.3ng/L).However,Plasma levels CCK and CGRP were significantly increased through 3h and 7d following TBI (126-691% increases),with the peak at 72 h.Compared with control (VIP, 13.6±1.4ng/g;CGRP,70.6±17.7ng/g);VIP and CGRP levels in jejunum were significantly increased at 3h after TBI (VIP,35.4±5.0ng/g;CGRP,103.8±22.1ng/g),and declined gradually at 12 h and 2d h (VIP,16.5±1.8ng/g,5.5±1.4ng/g;CGRP,34.9±9.7ng/g, 18.5±7.7ng/g),but were significantly increased again at 72 h (VIP, 48.7±9.5ng/g; CGRP,142.1±24.3ng/g),then declined in various degrees on d 7 (VIP, 3.8±1.1ng/g; CGRP, 102.5±18.1ng/g).The CCK levels in jejunum were found to change in a similar trend as that in p
基金This project is supported by Special Foundation for Major State Basic Research of China (Project 973, No.G1998030415)
文摘In the industrial process situation, principal component analysis (PCA) is ageneral method in data reconciliation. However, PCA sometime is unfeasible to nonlinear featureanalysis and limited in application to nonlinear industrial process. Kernel PCA (KPCA) is extensionof PCA and can be used for nonlinear feature analysis. A nonlinear data reconciliation method basedon KPCA is proposed. The basic idea of this method is that firstly original data are mapped to highdimensional feature space by nonlinear function, and PCA is implemented in the feature space. Thennonlinear feature analysis is implemented and data are reconstructed by using the kernel. The datareconciliation method based on KPCA is applied to ternary distillation column. Simulation resultsshow that this method can filter the noise in measurements of nonlinear process and reconciliateddata can represent the true information of nonlinear process.
文摘Based on the composite modification technology of the surface of nano Silicondioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on thesurface of nano silicon dioxide. The modification mechanism and the bonding status on the surface ofnano silicon dioxide after modification were suggested via the results of the infrared spectrum,transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formedby hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxideto form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto thesurface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer throughfree radical polymerization between the double bonds on the surface of nano silicon dioxide andstyrene under the action of initiating agent. The dispersibility of nano silicon dioxide and thecontrollability of surface modification of nano silicon dioxide can be greatly improved by themodification process.
文摘To get the influence of the randomness of longitudinal resistance of ballast bed (LRBB) on track-bridge interaction, the statistical law of LRBB was studied with existing test data and the Shapiro-Wilk test. Based on the principle of track-bridge interaction, a rail-sleeper-bridge-pier integrated simulation model that could consider the randomness of LRBB was established. Taking a continuous beam bridge for the heavy-haul railway as an example, the effect of the randomness of LRBB on the mechanical behavior of continuous welded rail (CWR) on bridges under typical conditions was carefully examined with a random sampling method and the simulation model. The results show that the LRBB corresponding sleeper displacement of 2 mm obeys a normal distribution. When the randomness of LRBB is considered, the amplitudes of rail expansion force, rail bending force, rail braking force and rail broken gap all follow normal distribution. As the standard deviations of the four indexes are small, which indicates the randomness of LRBB has little effect on track-bridge interaction. The distributions of the four indexes make it possible to design CWR on bridges with the limit state method.
基金We thank the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(QNLM)(No.2022QNLM030003-2)the Fundamental Research Funds for the Central Universities,Ocean University of China,Qingdao National Laboratory for Marine Science and Technology(Nos.LMDBCXRC201902 and LMDBCXRC201903)+2 种基金Taishan Scholar Program of Shandong Province(Nos.tsqn201909056 and tsqn202103152)National Natural Science Foundation of China(No.22171251)Natural Science Foundation of Shandong Province(No.ZR2021QB033)for financial support.
文摘A catalyst-free and atom-economical[4+3]cycloaddition of azadienes with C,N-cyclic azomethine imines has been developed,providing an efficient and environmentally benign access to 1,2,4-triazepines with high diastereoselectivities and yields.This reaction can be performed in 2-methyltetrahydrofuran under mild conditions smoothly.
基金the National Natural Science Foundation of China for financial support to this work under Grant NSFC No.12072064.
文摘The collocation method is a widely used numerical method for science and engineering problems governed by partial differential equations.This paper provides a comprehensive review of collocation methods and their applications,focused on elasticity,heat conduction,electromagnetic field analysis,and fluid dynamics.The merits of the collocation method can be attributed to the need for element mesh,simple implementation,high computational efficiency,and ease in handling irregular domain problems since the collocation method is a type of node-based numerical method.Beginning with the fundamental principles of the collocation method,the discretization process in the continuous domain is elucidated,and how the collocation method approximation solutions for solving differential equations are explained.Delving into the historical development of the collocation methods,their earliest applications and key milestones are traced,thereby demonstrating their evolution within the realm of numerical computation.The mathematical foundations of collocation methods,encompassing the selection of interpolation functions,definition of weighting functions,and derivation of integration rules,are examined in detail,emphasizing their significance in comprehending the method’s effectiveness and stability.At last,the practical application of the collocation methods in engineering contexts is emphasized,including heat conduction simulations,electromagnetic coupled field analysis,and fluid dynamics simulations.These specific case studies can underscore collocation method’s broad applicability and effectiveness in addressing complex engineering challenges.In conclusion,this paper puts forward the future development trend of the collocation method through rigorous analysis and discussion,thereby facilitating further advancements in research and practical applications within these fields.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1603300 and 2022YFA1603200)the Science Challenge Project(Grant No.TZ2018005)in China+1 种基金the National Natural Science Foundation of China(Grant Nos.11805188 and 12175209)the Laser Fusion Research Center Funds for Young Talents(Grant No.RCFPD6-2022-1).
文摘We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on thepoint-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peakcompression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metalmicrowire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamicsimulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, arealdensities of the targets were evaluated.
文摘AIM：To study the operativ injury,post-operative complications,the hospitalization time,the post-operative survival rate of ultrasonic aspiration hepatectomy with a domestic new type of ultrasonic surgical device in comparison with that of conventional techniques of hepatectomy.METHODS:A total136patients with hepatocellular carcinoma(HCC,including 13patinents in 1991and 124consecutive patients from July1995to December2000)underwent ultrasonic aspiration in liver resection(groupT)and 179 HCCpatients received conventional hepatectomy during the corresponding period(groupC).The results of the two groups were compared statistically.RESULTS:There was no significant difference in the mean operation time between groupT(152±11min)and C(144±11min).No operation or hospital edath occurred in both groups.In groupT,the mean volumes of bleeding(463±15ml)and bolld transfusion(381±12ml)were markedly less than those in groupC(557±20ml,and507±18ml,respectively,P<0.05).The mean hospitalization time of groupT(8.9±0.6d)was markedly shorter than that of groupC(11.7d±0.6d)(P<0.05).The incidence of complications in groupTwas markedly lower than in groupC,post-operative jaundice occurred in4/136and31/179,respectively(P<0.05).liver failurein0/136and2/179,cholorrhea in0/136and6/179,hydrothoraxin21/136and39/179(P<0.05).ascices in9/136and2/179,cholrrheain0/136and6/179,hydrothorax in21/136and 39/179(P<0.05),ascices in 9/136and 54/179,respectively(P<0.05),while the 3-year survival rate of groupT(64.2%)increased markedly as compared with that of groupC(55.7%)(P<0.01).CONCLUSION:The ultrasonic aspiration hepatectomy with a domestic new type of ultrasonic surgical device could evidently reduce the operative injury and post-operative complications,shorten the hospitalization,time and prolong the survivals of HCC,patients.
基金funded by the National Natural Science Foundation of China(No.62076044)Scientific Research Foundation of Chongqing University of Technology(No.2020ZDZ015).
文摘Alzheimer’s disease(AD)is a complex,progressive neurodegenerative disorder.The subtle and insidious onset of its pathogenesis makes early detection of a formidable challenge in both contemporary neuroscience and clinical practice.In this study,we introduce an advanced diagnostic methodology rooted in theMed-3D transfermodel and enhanced with an attention mechanism.We aim to improve the precision of AD diagnosis and facilitate its early identification.Initially,we employ a spatial normalization technique to address challenges like clarity degradation and unsaturation,which are commonly observed in imaging datasets.Subsequently,an attention mechanism is incorporated to selectively focus on the salient features within the imaging data.Building upon this foundation,we present the novelMed-3D transfermodel,designed to further elucidate and amplify the intricate features associated withADpathogenesis.Our proposedmodel has demonstrated promising results,achieving a classification accuracy of 92%.To emphasize the robustness and practicality of our approach,we introduce an adaptive‘hot-updating’auxiliary diagnostic system.This system not only enables continuous model training and optimization but also provides a dynamic platform to meet the real-time diagnostic and therapeutic demands of AD.
基金supported by the National Natural Science Foundation of China(Nos.52222403,52074333,52120105007)Taishan Scholar Young Expert(No.tsqn202211079)。
文摘Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.
文摘This paper presents a combined method to model grain crushing effects with discrete element method.This method combines the two most commonly used concepts to model grain crushing in DEM,i.e.the replacement method and the agglomerate method,so that it is both accurate and efficient.The method can be easily implemented.The performance is shown by several DEM simulations of biaxial tests.Particles with different crush-abilities are modeled.DEM simulation results with and without grain crushing are compared and discussed.The change of grain size distribution due to grain crushing is also investigated.
基金partially supported by the China national R&D Key Research Program(2019YFB1705702)the National Natural Science Foundation of China(62273233)。
文摘Dear Editor,This letter proposes a process-monitoring method based on temporal feature agglomeration and enhancement,in which a novel feature extractor called contrastive feature extractor(CFE)extracts the temporal and relational features among process parameters.Then the feature representations are enhanced by maximizing the separation among different classes while minimizing the scatter within each class.
文摘The basie idea and method about determination of the feature line equations and how to apply them to the numerical control of the press bending of panei skins were introduced. Research indicates that it is feasible to realize the self adapting incremental press bending by adopting the feature line equation. The feature line equation, which is based on the database of the status of practical processes, can be adjusted in time, and the forming precision can be improved. It is important to correctly select and reasonably predict the feature line equations to enhance the accuracy of the incremental press bending based on the feature line database and algorithm. The determination of the feature line equation settles necessary data foundation for further research on the database of self-adapting incremental press bending, and it supplies a new clue for the development of self-adapting incremental press bending.
文摘PREPARATION of HMW DNA (Megabase-size) is the basis for construction of genomic library with large DNA inserts such as bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC), and for long-range physical mapping. It can also be used for the macro-study of repeat sequences. Since HMW DNA during preparation is inclined to be sheared physically and digested by internal nucleases, it is very difficult to prepare the HMW DNA. Initially, plant HMW DNA was prepared by embedding protoplasts in the low melting-point (LMP) agarose; however, it had several disadvantages: (ⅰ) Culture of protoplasts was time-consuming, costly and tedious. ( ⅱ ) It was only used successfully for limited
基金supported by the National Key Research and Development Program of China (No.2016YFD0501405)the China Postdoctoral Science Foundation (No.2018M630245)the Beijing Postdoctoral Research Foundation (No.2017-ZZ-137).
文摘The discharge of slaughterhouse wastewater(SWW)is increasing and its wastewater has to be treated thoroughly to avoid the eutrophication.The hybrid zeolite-based ion-exchange and sulfur autotrophic denitrification(IX-AD)process was developed to advanced treat SWW after traditional secondary biological process.Compared with traditional sulfur oxidizing denitrification(SOD),this study found that IX-AD column showed:(1)stronger ability to resist NO_(3)^(-) pollution load,(2)lower SO_(4)^(2-) productivity,and(3)higher microbial diversity and richness.Liaoning zeolites addition guaranteed not only the standard discharge of NH_(4)^(+)-N,but also the denitrification performance and effluent TN.Especially,when the ahead secondary biological treatment process run at the ultra-high load,NO_(3)-N removal efficiency for IX-AD column was still~100%,whereas only 64.2%for control SOD column.The corresponding average effluent TN concentrations for IX-AD and SOD columns were 5.89 and 65.55 mg/L,respectively.Therefore,IX-AD is a promising technology for advanced SWW treatment and should be widely researched and popularized.
基金the National Nature Science Foundation of China(No.60974119)the Subject Construction of Shanghai University of Engineering Science(No.2018xk-B-09)the Young Teacher Training Scheme of Shanghai Universities(No.ZZGCD15007)
文摘Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling among inputs and outputs. In this paper, model predictive control(MPC) method based on multi-model and double layered optimization is introduced for coordinated control of USC unit running in sliding pressure mode and fixed pressure mode. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. output power, main steam temperature and main steam pressure). The step responses for the dynamic matrix control(DMC) are constructed using the three inputs by the three outputs under both pressure control mode. Piecewise models are built at selected operation points. In simulation, the output power follows load demand quickly and main steam temperature can be controlled around the setpoint closely in load tracking control. The simulation results show the effectiveness of the proposed methods.
