Since the plasticity of soil and the irregular shape of the excavation,the efficiency and stability of the traditional local radial basis function(RBF)collocation method(LRBFCM)are inadequate for analyzing three-dimen...Since the plasticity of soil and the irregular shape of the excavation,the efficiency and stability of the traditional local radial basis function(RBF)collocation method(LRBFCM)are inadequate for analyzing three-dimensional(3D)deformation of deep excavation.In this work,the technique known as the direct method,where the local influence nodes are collocated on a straight line,is introduced to optimize the LRBFCM.The direct method can improve the accuracy of the partial derivative,reduce the size effect caused by the large length-width ratio,and weaken the influence of the shape parameters on the LRBFCM.The mapping technique is adopted to transform the physical coordinates of a quadratic-type block to normalized coordinates,in which the deformation problem can easily be solved using the direct method.The stability of the LRBFCM is further modified by considering the irregular shape of 3D excavation,which is divided into several quadratic-type blocks.The soil’s plasticity is described by the Drucker-Prager(D-P)model.The improved LRBFCM is integrated with the incremental method to analyze the plasticity.Five different examples,including strip excavations and circular excavations,are presented to validate the proposed approach’s efficiency.展开更多
Bio-inspired porous metallic scaffolds have tremendous potential to be used as artificial bone substitutes.In this work,a radially graded lattice structure (RGLS),which mimics the structures of natural human bones,was...Bio-inspired porous metallic scaffolds have tremendous potential to be used as artificial bone substitutes.In this work,a radially graded lattice structure (RGLS),which mimics the structures of natural human bones,was designed and processed by laser powder bed fusion of martensitic Ti-rich TiNi powder.The asymmetric tension-compression behaviour,where the compressive strength is significantly higher than the tensile strength,is observed in this Ti-rich TiNi material,which echoes the mechanical behaviour of bones.The morphologies,mechanical properties,deformation behaviour,and biological compatibility of RGLS samples were characterised and compared with those in the uniform lattice structure.Both the uniform and RGLS samples achieve a relative density higher than 99%.The graded porosities and pore sizes in the RGLS range from 40%-80% and 330-805 µm,respectively,from the centre to the edge.The chemical etching has significantly removed the harmful partially-melted residual powder particles on the lattice struts.The compressive yield strength of RGLS is 71.5 MPa,much higher than that of the uniform sample (46.5 MPa),despite having a similar relative density of about 46%.The calculated Gibson-Ashby equation and the deformation behaviour simulation by finite element suggest that the dense outer regions with high load-bearing capability could sustain high applied stress,improving the overall strength of RGLS significantly.The cell proliferation study suggests better biological compatibility of the RGLS than the uniform structures.The findings highlight a novel strategy to improve the performance of additively manufactured artificial implants by bio-inspiration.展开更多
Coronavirus disease 2019(COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2(SARS-Co V-2), has spread rapidly worldwide with high rates of transmission and substantial mortality. To date, how...Coronavirus disease 2019(COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2(SARS-Co V-2), has spread rapidly worldwide with high rates of transmission and substantial mortality. To date, however, no effective treatments or enough vaccines for COVID-19 are available. The roles of angiotensin converting enzyme 2(ACE2) and spike protein in the treatment of COVID-19 are major areas of research. In this study, we explored the potential of ACE2 and spike protein as targets for the development of antiviral agents against SARS-Co V-2. We analyzed clinical data, genetic data, and receptor binding capability.Clinical data revealed that COVID-19 patients with comorbidities related to an abnormal reninangiotensin system exhibited more early symptoms and poorer prognoses. However, the relationship between ACE2 expression and COVID-19progression is still not clear. Furthermore, if ACE2 is not a good targetable protein, it would not be applicable across a wide range of populations. The spike-S1 receptor-binding domain that interacts with ACE2 showed various amino acid mutations based on sequence analysis. We identified two spike-S1 point mutations(V354 F and V470 A) by receptorligand docking and binding enzyme-linked immunosorbent assays. These variants enhanced the binding of the spike protein to ACE2 receptors and were potentially associated with increased infectivity. Importantly, the number of patients infected with the V354 F and V470 A mutants has increased with the development of the SARS-Co V-2 pandemic. These results suggest that ACE2 and spike-S1 are likely not ideal targets for the design of peptide drugs to treat COVID-19 in different populations.展开更多
To develop a depth filter based on the electrostatic adsorption principle, positively charged microporous ceramic membrane was prepared from a diatomaceous earth ceramic membrane.The internal surface of the highly por...To develop a depth filter based on the electrostatic adsorption principle, positively charged microporous ceramic membrane was prepared from a diatomaceous earth ceramic membrane.The internal surface of the highly porous ceramic membrane was coated with uniformly distributed electropositive nano-Y2O3 coating. The dye removal performance was evaluated through pressurized filtration tests using Titan Yellow aqueous solution. It showed that positively charged microporous ceramic membrane exhibited a flow rate of 421 L/（m^2·hr） under the trans-membrane pressure of 0.03 bar. Moreover it could effectively remove Titan Yellow with feed concentration of 10 mg/L between pH 3 to 8. The removal rate increased with the enhancement of the surface charge properties with a maximum rejection of 99.6%. This study provides a new and feasible method of removing organic dyes in wastewater. It is convinced that there will be a broad market for the application of charged ceramic membrane in the field of dye removal or recovery from industry wastewater.展开更多
A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis（methylamino）borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine（PBN）.This asymmetric alkyl...A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis（methylamino）borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine（PBN）.This asymmetric alkylaminoborazine was synthesized by an aminolysis reaction of 2,4,6-trichloroborazine（TCB） with different amines under mild conditions.This route turns out to be much cheaper and simpler than the conventional routes.The chemical composition,structure,molecular weights and ceramic yield were investigated by EA,FTIR,NMR,GPC and TG analysis.The PBN exhibits suitable rheological property for melt-spinning, which suggests that it is a potential precursor for BN fibers.展开更多
BACKGROUND Drain-site hernia(DSH)has an extremely low morbidity and has rarely been reported.Small bowel obstruction is a frequent concurrent condition in most cases of DSH,which commonly occurs at the≥10 mm drain-si...BACKGROUND Drain-site hernia(DSH)has an extremely low morbidity and has rarely been reported.Small bowel obstruction is a frequent concurrent condition in most cases of DSH,which commonly occurs at the≥10 mm drain-site.Here we report a rare case of DSH at the lateral 5 mm port site one month postoperatively without visceral incarceration.Simultaneously,a brief review of the literature was conducted focusing on the risk factors,diagnosis,and prevention strategies for DSH.CASE SUMMARY A 76-year-old male patient was admitted to our institution with intermittent abdominal pain and a local abdominal mass which occurred one month after laparoscopic radical resection of rectal cancer one year ago.A computed tomography scan showed an abdominal wall hernia at the 5 mm former drain-site in the left lower quadrant,and that the content consisted of the large omentum.An elective herniorrhaphy was performed by closing the fascial defect and reinforcing the abdominal wall with a synthetic mesh simultaneously.The postoperative period was uneventful.The patient was discharged seven days after the operation without surgery-related complications at the 1-mo follow-up visit.CONCLUSION Emphasis should be placed on DSH despite the decreased use of intra-abdominal drainage.It is recommended that placement of a surgical drainage tube at the≥10 mm trocar site should be avoided.Moreover,it is advisable to have a comprehensive understanding of the risk factors for DSH and complete closure of the fascial defect at the drainage site for high-risk patients.展开更多
The unique deposition manner of additive manufacturing(AM)allows the near-net-shaping of components with multiple materials configurations and complex geometries,which sheds light on the process of high-performance me...The unique deposition manner of additive manufacturing(AM)allows the near-net-shaping of components with multiple materials configurations and complex geometries,which sheds light on the process of high-performance metal matrix composites(MMCs).This work explores laser powder bed fusion(LPBF)AM of SiC-reinforced maraging steel MMCs to consolidate the merits of both ceramics and metal matrix for improving overall properties.The laser processing parameters were systematically optimised based on the density,roughness and hardness of the deposited samples.The effects of SiC content on the microstructures,mechanical properties,tribological performance,and wear resistance are elucidated.SiC particles are refined with uniform distribution in the metal matrix after laser processing.The highest tensile strength reaches 1611 MPa together with an elongation of about 10.1%with 3 vol%SiC addition.The tribological performance of MMCs is investigated by studying the coefficient of friction(COF),wear rate,and worn morphology.The COF has been slightly reduced with the SiC addition,and the wear rate of MS reduced from 3.25×10^(-5) to 1.72×10^(-5)mm^(3)/Nm with the 12 vol% SiC addition.The underlying wear mechanisms are also investigated.Besides,the corrosion behaviour of MMCs is also investigated;the addition of SiC(≥6 vol%)has improved the corrosion properties of the matrix.展开更多
基金supported by grants from the National Natural Science Foundation of China(Nos.12172159 and 12362019).
文摘Since the plasticity of soil and the irregular shape of the excavation,the efficiency and stability of the traditional local radial basis function(RBF)collocation method(LRBFCM)are inadequate for analyzing three-dimensional(3D)deformation of deep excavation.In this work,the technique known as the direct method,where the local influence nodes are collocated on a straight line,is introduced to optimize the LRBFCM.The direct method can improve the accuracy of the partial derivative,reduce the size effect caused by the large length-width ratio,and weaken the influence of the shape parameters on the LRBFCM.The mapping technique is adopted to transform the physical coordinates of a quadratic-type block to normalized coordinates,in which the deformation problem can easily be solved using the direct method.The stability of the LRBFCM is further modified by considering the irregular shape of 3D excavation,which is divided into several quadratic-type blocks.The soil’s plasticity is described by the Drucker-Prager(D-P)model.The improved LRBFCM is integrated with the incremental method to analyze the plasticity.Five different examples,including strip excavations and circular excavations,are presented to validate the proposed approach’s efficiency.
基金financially supported by the National Natural Science Foundation of China(52005189)Guangdong Basic and Applied Basic Research Foundation(2019A1515110542 and 2020A1515110699)+1 种基金Guangzhou Foreign Cooperation Projects(2020B1212060049 and 201704030067)Guangdong Academy of Sciences and the University of Birmingham(Contract 17-0551).
文摘Bio-inspired porous metallic scaffolds have tremendous potential to be used as artificial bone substitutes.In this work,a radially graded lattice structure (RGLS),which mimics the structures of natural human bones,was designed and processed by laser powder bed fusion of martensitic Ti-rich TiNi powder.The asymmetric tension-compression behaviour,where the compressive strength is significantly higher than the tensile strength,is observed in this Ti-rich TiNi material,which echoes the mechanical behaviour of bones.The morphologies,mechanical properties,deformation behaviour,and biological compatibility of RGLS samples were characterised and compared with those in the uniform lattice structure.Both the uniform and RGLS samples achieve a relative density higher than 99%.The graded porosities and pore sizes in the RGLS range from 40%-80% and 330-805 µm,respectively,from the centre to the edge.The chemical etching has significantly removed the harmful partially-melted residual powder particles on the lattice struts.The compressive yield strength of RGLS is 71.5 MPa,much higher than that of the uniform sample (46.5 MPa),despite having a similar relative density of about 46%.The calculated Gibson-Ashby equation and the deformation behaviour simulation by finite element suggest that the dense outer regions with high load-bearing capability could sustain high applied stress,improving the overall strength of RGLS significantly.The cell proliferation study suggests better biological compatibility of the RGLS than the uniform structures.The findings highlight a novel strategy to improve the performance of additively manufactured artificial implants by bio-inspiration.
基金supported by the National Key Research and Development Program of China (2018YFD0900602)National Natural Science Foundation of China (31970388, 31701234)+3 种基金Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)Natural Science Foundation of the Jiangsu Higher Education Institutions (17KJB180006)Natural Science Foundation from Jiangsu Province (BK20160043, BK20151546, 15KJA180004and BK20171035)Jiangsu Distinguished Professor Funding。
文摘Coronavirus disease 2019(COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2(SARS-Co V-2), has spread rapidly worldwide with high rates of transmission and substantial mortality. To date, however, no effective treatments or enough vaccines for COVID-19 are available. The roles of angiotensin converting enzyme 2(ACE2) and spike protein in the treatment of COVID-19 are major areas of research. In this study, we explored the potential of ACE2 and spike protein as targets for the development of antiviral agents against SARS-Co V-2. We analyzed clinical data, genetic data, and receptor binding capability.Clinical data revealed that COVID-19 patients with comorbidities related to an abnormal reninangiotensin system exhibited more early symptoms and poorer prognoses. However, the relationship between ACE2 expression and COVID-19progression is still not clear. Furthermore, if ACE2 is not a good targetable protein, it would not be applicable across a wide range of populations. The spike-S1 receptor-binding domain that interacts with ACE2 showed various amino acid mutations based on sequence analysis. We identified two spike-S1 point mutations(V354 F and V470 A) by receptorligand docking and binding enzyme-linked immunosorbent assays. These variants enhanced the binding of the spike protein to ACE2 receptors and were potentially associated with increased infectivity. Importantly, the number of patients infected with the V354 F and V470 A mutants has increased with the development of the SARS-Co V-2 pandemic. These results suggest that ACE2 and spike-S1 are likely not ideal targets for the design of peptide drugs to treat COVID-19 in different populations.
基金supported by the National Natural Science Foundation of China (No. 51202292)
文摘To develop a depth filter based on the electrostatic adsorption principle, positively charged microporous ceramic membrane was prepared from a diatomaceous earth ceramic membrane.The internal surface of the highly porous ceramic membrane was coated with uniformly distributed electropositive nano-Y2O3 coating. The dye removal performance was evaluated through pressurized filtration tests using Titan Yellow aqueous solution. It showed that positively charged microporous ceramic membrane exhibited a flow rate of 421 L/（m^2·hr） under the trans-membrane pressure of 0.03 bar. Moreover it could effectively remove Titan Yellow with feed concentration of 10 mg/L between pH 3 to 8. The removal rate increased with the enhancement of the surface charge properties with a maximum rejection of 99.6%. This study provides a new and feasible method of removing organic dyes in wastewater. It is convinced that there will be a broad market for the application of charged ceramic membrane in the field of dye removal or recovery from industry wastewater.
基金support from the National 863 Program(No.2006AA03A217)
文摘A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis（methylamino）borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine（PBN）.This asymmetric alkylaminoborazine was synthesized by an aminolysis reaction of 2,4,6-trichloroborazine（TCB） with different amines under mild conditions.This route turns out to be much cheaper and simpler than the conventional routes.The chemical composition,structure,molecular weights and ceramic yield were investigated by EA,FTIR,NMR,GPC and TG analysis.The PBN exhibits suitable rheological property for melt-spinning, which suggests that it is a potential precursor for BN fibers.
基金Supported by the Project of Health Commission of Hunan Province of ChinaNO. 20201853
文摘BACKGROUND Drain-site hernia(DSH)has an extremely low morbidity and has rarely been reported.Small bowel obstruction is a frequent concurrent condition in most cases of DSH,which commonly occurs at the≥10 mm drain-site.Here we report a rare case of DSH at the lateral 5 mm port site one month postoperatively without visceral incarceration.Simultaneously,a brief review of the literature was conducted focusing on the risk factors,diagnosis,and prevention strategies for DSH.CASE SUMMARY A 76-year-old male patient was admitted to our institution with intermittent abdominal pain and a local abdominal mass which occurred one month after laparoscopic radical resection of rectal cancer one year ago.A computed tomography scan showed an abdominal wall hernia at the 5 mm former drain-site in the left lower quadrant,and that the content consisted of the large omentum.An elective herniorrhaphy was performed by closing the fascial defect and reinforcing the abdominal wall with a synthetic mesh simultaneously.The postoperative period was uneventful.The patient was discharged seven days after the operation without surgery-related complications at the 1-mo follow-up visit.CONCLUSION Emphasis should be placed on DSH despite the decreased use of intra-abdominal drainage.It is recommended that placement of a surgical drainage tube at the≥10 mm trocar site should be avoided.Moreover,it is advisable to have a comprehensive understanding of the risk factors for DSH and complete closure of the fascial defect at the drainage site for high-risk patients.
基金This work was supported by the National Natural Science Foundation of China(52005189)Guangdong Basic and Applied Basic Research Foundation(2019A1515110542)Guangdong Special Support Program(2019BT02C629).
文摘The unique deposition manner of additive manufacturing(AM)allows the near-net-shaping of components with multiple materials configurations and complex geometries,which sheds light on the process of high-performance metal matrix composites(MMCs).This work explores laser powder bed fusion(LPBF)AM of SiC-reinforced maraging steel MMCs to consolidate the merits of both ceramics and metal matrix for improving overall properties.The laser processing parameters were systematically optimised based on the density,roughness and hardness of the deposited samples.The effects of SiC content on the microstructures,mechanical properties,tribological performance,and wear resistance are elucidated.SiC particles are refined with uniform distribution in the metal matrix after laser processing.The highest tensile strength reaches 1611 MPa together with an elongation of about 10.1%with 3 vol%SiC addition.The tribological performance of MMCs is investigated by studying the coefficient of friction(COF),wear rate,and worn morphology.The COF has been slightly reduced with the SiC addition,and the wear rate of MS reduced from 3.25×10^(-5) to 1.72×10^(-5)mm^(3)/Nm with the 12 vol% SiC addition.The underlying wear mechanisms are also investigated.Besides,the corrosion behaviour of MMCs is also investigated;the addition of SiC(≥6 vol%)has improved the corrosion properties of the matrix.
