Using panel data for 29 provinces in China during 1990-2004, the present paper attempts to explore a possible link between financial development and China＇s foreign trade. Three measures of comparative advantage in m...Using panel data for 29 provinces in China during 1990-2004, the present paper attempts to explore a possible link between financial development and China＇s foreign trade. Three measures of comparative advantage in manufactured goods have been applied in our study, including Balassa＇s revealed comparative advantage, the net manufactured export index, and the Michaely index. We also use four indicators of financial development to identify the different functions of regional financial development, and to determine both size and efficiency features of financial institutions. The estimation results suggest that besides factor endowments, foreign firms and infrastructure, financial development has a quantitatively large and robust effect on China ＇ s manufactured goods trade. Therefore, further reform of China＇s financial system should be encouraged to fully exploit the comparative advantage of China＇s foreign trade.展开更多
Six representative parent rocks of sand, including limestone, quartzite, gneisses, granite, Basalt and Marble were selected to conduct a systematical research on the effects of various lithologies of manufactured sand...Six representative parent rocks of sand, including limestone, quartzite, gneisses, granite, Basalt and Marble were selected to conduct a systematical research on the effects of various lithologies of manufactured sand on the workability, mechanism properties, volume stability and durability of manufacturedsand concrete. The experimental results show that the strength of manufactured-sand concrete is slightly higher than that of natural-sand concrete. Furthermore, substituting 15% cement of the concrete mixture with equal quantity of the six different lithology stone powder respectively, the data indicated that they can improve the concrete’s workability, postpone the plastic cracking time, enhance the anti-cracking grade, and have no obvious effect on the properties of antifreeze and sulfate attack resistance but reduce the capability to resist chloride ion penetration. Moreover, the differences in concrete’s workability, mechanism properties, volume stability and durability caused by various lithologies of manufactured sand and stone powder were not significant and the influence of lithology variety on the macro properties of concrete could be neglected eventually.展开更多
The relation between the methylene blue （MB） value of MS and its limestone powder content and clay content was investigated. The effects of MB values ranging from 0.35 to 2.5 on the workability of fresh concrete, th...The relation between the methylene blue （MB） value of MS and its limestone powder content and clay content was investigated. The effects of MB values ranging from 0.35 to 2.5 on the workability of fresh concrete, the mechanical properties, the resistance to freezing as well as the resistance to chlorine ion permeation of the hardened concrete were all investigated. The experimental results showed that the MB value had no correlation with the limestone powder content of MS, while it was directly related to the clay content. With an increase of MB value, concrete workability decreased, as did the flexural and 7-day compressive strengths, however, the 28-day compressive strength was not affected. Furthermore, influence of MB value on concretes of different strength levels was different. For low-strength concretes, an increase of MB value could improve its impermeability, but this was not the case for high-strength concretes. Instead, their resistance to chloride ion permeability decreased slightly. However, even a slight increase in MB value remarkably accelerated freeze-thaw damage of MS concrete. It was thus concluded that the critical MB value of 1.4 would not cause significant deterioration in the performance of MS concretes.展开更多
River sand is an essential component used as a fine aggregate in mortar and concrete.Due to unrestrained exploitation,river sand resources are gradually being exhausted.This requires alternative solutions.This study d...River sand is an essential component used as a fine aggregate in mortar and concrete.Due to unrestrained exploitation,river sand resources are gradually being exhausted.This requires alternative solutions.This study deals with the properties of cement mortar containing different levels of manufactured sand(MS)based on quartzite,used to replace river sand.The river sand was replaced at 20%,40%,60%and 80%with MS(by weight or volume).The mechanical properties,transfer properties,and microstructure were examined and compared to a control group to study the impact of the replacement level.The results indicate that the compressive strength can be improved by increasing such a level.The strength was improved by 35.1%and 45.5%over that of the control mortar at replacement levels of 60%and 80%,respectively.Although there was a weak link between porosity and gas permeability in the mortars with manufactured sand,the gas permeability decreased with growing the replacement level.The microstructure of the MS mortar was denser,and the cement paste had fewer microcracks with increasing the replacement level.展开更多
The relation between methylene blue （MB） value of MS and its limestone dust content and clay content was investigated. The effects of MB value ranging from 0.35 to 2.5 on the workability of fresh concrete and crack ...The relation between methylene blue （MB） value of MS and its limestone dust content and clay content was investigated. The effects of MB value ranging from 0.35 to 2.5 on the workability of fresh concrete and crack propagation characteristics at the age of 24 hours, and effects on the mechanical properties, dry shrinkage of the harden concrete were tested. The experimental results show that the MB value is not related with the limestone dust content of MS, but in direct proportion to clay content. With the increase of MB value, the concrete workability decreases, and the flexural strength and 7 d compressive strength reduce markedly, whearas the 28 d compressive strength is not affected. When the MB-value is less than or equal to 1.35, the change of the MB-value has a little influence on early plastic cracking and dry shrinkage property of concrete, but when the MB-value is more than 1.35, the tendency of plastic cracking and dry shrinkage is remarkable.展开更多
Manufactured nanomaterials with unique properties have been extensively applied in various indus-trial,agricultural or medical fields.However,some of the properties have been identified to be closely related to nanoma...Manufactured nanomaterials with unique properties have been extensively applied in various indus-trial,agricultural or medical fields.However,some of the properties have been identified to be closely related to nanomaterial toxicity.The"nano-paradox"has aroused concerns over the use and develop-ment of nanotechnology,which makes it difficult for regulatory agencies to regulate nanomaterials.The key to fulfilling proper nanomaterial regulation lies in the adequate understanding of the impact of nanomaterial properties on nano-bio interactions.To this end,we start the present work with a brief intro-duction to nano-bio interactions at different levels.Based on that,how key toxicity-associated properties of manufactured nanomaterials(i.e.,size,shape,chemical composition,surface properties,biocorona formation,agglomeration and/or aggregation state,and biodegradability)impact their toxicokinetics,cel-lular uptake,trafficking and responses,and toxicity mechanisms is deeply explored.Moreover,advanced analytical methods for studying nano-bio interactions are introduced.Furthermore,the current reg-ulatory and legislative frameworks for nanomaterial-containing products in different regions and/or countries are presented.Finally,we propose several challenges facing the nanotoxicology field and their possible solutions to shed light on the safety evaluation of nanomaterials.展开更多
Compared with bar code and quick response( QR) code in the storage and retailing management of textiles, the ultra-high frequency( UHF) radio frequency identification( RFID) tags have high information capacity as well...Compared with bar code and quick response( QR) code in the storage and retailing management of textiles, the ultra-high frequency( UHF) radio frequency identification( RFID) tags have high information capacity as well as reliability in complex environmental conditions. In this study,the UHF RFID tags with perfect integration with textiles are assembled with screen-printed antenna on woven water-mark nylon fabric and Alien UHF integrated circuit( IC), and their reading performance under various washing and bending conditions is evaluated by an RFID reader. The results show that the tags after fifty bending( both arch and sink) cycles of screen-printed antenna still have reading distance more than 5.5 m,and an average reading distance is over 4.0 m after five washing cycles. The experimental results demonstrate that the tag antenna on the water-mark fabric can be manufactured by the screen-printing technology,and a coating process on this fabric facilitates the reading performance and the resistance against complex mechanical impact.展开更多
By the addition of superplasticizer and air entraining agent,manufactured sand selfcompacting concrete(MS SCC)with slump flow varying from 500 to 700 mm and air content varying from 2.0%to 9.0%were prepared and the pu...By the addition of superplasticizer and air entraining agent,manufactured sand selfcompacting concrete(MS SCC)with slump flow varying from 500 to 700 mm and air content varying from 2.0%to 9.0%were prepared and the pumpability of MS SCC was studied by a sliding pipe rheometer(Sliper).According to the Kaplan’s model,the initial pump pressure and the pump resistance of MS SCC were obtained.Meanwhile,rheological properties including the yield stress and the plastic viscosity of MS SCC were measured by a rheometer.The experimental results show that the increase of slump flow contributes to a higher pumpability and a proper air content,i e,6%is beneficial for the pumpability of MS SCC.Due to the existence of stone powder and stronger angularity of MS,the initial pump pressure of MS SCC is only about 60%-88%that of river sand(RS)SCC with the same slump flow and air content,indicating that MS SCC possesses a higher pumpability than RS SCC.展开更多
A tremendous amount of non-biodegradable waste is created during mining and processing tasks of layered stones like marble.Over time,this has become a global problem because it harms the environment in multiple ways.H...A tremendous amount of non-biodegradable waste is created during mining and processing tasks of layered stones like marble.Over time,this has become a global problem because it harms the environment in multiple ways.Hence,it is necessary to find an alternate way to securely dispose and reuse marble wastes.The construction sector is one of the significant consumers of natural resources for the production of material binders and aggregates.As a result,in recent years,number of researchers have carried out studies in which various kinds of marble waste have been incorporated into concrete with the intention of substituting either cement or aggregates or both.This paper presents the effect of two locally sourced waste marble powders Kadapa marble powder(KMP)and Bethamcherla marble powder(BMP)as partial replacement of cement on mechanical and durability properties of high strength concrete(HSC).Their effect at different replacement levels in HSC is evaluated in compressive,indirect tensile and flexural strengths,elastic modulus,chloride penetration resistance and freeze-thaw durability properties.Micro-structural investigation is also conducted to evaluate their impact on the matrix of HSC containing waste marble powders as additional cementitious materials.Results show that the HSC consisting of KMP and BMP content of 10%and 15%,respectively exhibited higher mechanical and durability properties than the control HSC.Micro-structural investigation also supports this finding.It can be concluded that the use of marble powders as partial replacement of cement does not have any adverse impact on the properties of concrete.The use of KMP and BMP reduces the vast amount of energy required to produce cement,cost and time with reduction in environmental hazards.展开更多
To better understand and assess the effect of microfines on concrete properties, the synergetic effect of methylene blue value and content of microfines on properties of low and high strength concrete was studied and ...To better understand and assess the effect of microfines on concrete properties, the synergetic effect of methylene blue value and content of microfines on properties of low and high strength concrete was studied and then the relationships between the index of modified methylene blue value （MMBV） and concrete properties were investigated. The results show that relationships between MMBV and fresh and hardened properties of concrete can be fully established, and the correlation between MMBV and C60 concrete property is higher than the correlation between MMBV and C30 concrete. With the increase of MMBV, concrete workability and frost resistance decrease while drying shrinkage decreases; however, compressive strength and chloride-ion penetration resistance of C30 concrete have not been negatively affected whereas those of C60 concrete are significantly deteriorated when MMBV exceeds 100. To make use of microfines without remarkably damaging concrete quality, it is suggested that MMBV of microfines in MS used in C30 and C60 concrete be no more than 100.展开更多
To further improve the luminous efficiency of LED lightings,this Letter proposes a chip-on-board（COB）device by combining diced staggered V-shaped patterns and remote phosphors.The results show that the V-shaped patt...To further improve the luminous efficiency of LED lightings,this Letter proposes a chip-on-board（COB）device by combining diced staggered V-shaped patterns and remote phosphors.The results show that the V-shaped patterned COB（V-COB）with vertex angles from 120o to 150o can achieve a～17%output power increase（OPI）compared to the conventional COB.V-COB remote phosphor devices（RPDs）are then manufactured and tested.The luminous efficiency of the proposed RPD represents an 11.6%increase at the correlated color temperature of～3000 K.Such an improvement can be attributed to both the decreases of total internal reflections and phosphor backscatterings.展开更多
Recent Euro 5 and Euro 6 vehicle emission standards are the first ever initiative to control particles on a number basis at the source. Related standards are also desirable for ambient nanoparticles （taken in this ar...Recent Euro 5 and Euro 6 vehicle emission standards are the first ever initiative to control particles on a number basis at the source. Related standards are also desirable for ambient nanoparticles （taken in this article to be those below 300 rim） to protect against possible adverse effects on public health and the environment. However, there are a number of technical challenges that need to be tackled before developing a regulatory framework for atmospheric nanoparticles. Some of the challenges derive from a lack of standardisation of the key measurement parameters, including sampling, necessary for robust evaluation of particle number concentrations, especially in the context of insufficient knowledge of the physicochemical characteristics of emerging sources （i.e. bio-fuel derived and manufactured nanoparti- cles）. Ideally, ambient concentrations of primary particles could be linked to primary particle emissions by use of nanoparticle dispersion models, and secondary nanoparticles using photochemical modeling tools. The limitations in these areas are discussed. Although there is inadequate information on the exact biological mechanism through which these particles cause harm, it is argued that this should not in itself delay the introduction of regulation. This article reviews the missing links between the existing knowledge of nanoparticle number concentrations and the advances required to tackle the technical challenges implied in developing regulations.展开更多
To meet the requirements of construction of concretes filled in the steel tube arches,a C60 grade micro-expansive self-compacting concrete （SCC） was prepared from manufactured sand （MS）.The utilization of MS with ...To meet the requirements of construction of concretes filled in the steel tube arches,a C60 grade micro-expansive self-compacting concrete （SCC） was prepared from manufactured sand （MS）.The utilization of MS with a high content of quarry limestone fines was dealed for SCC applications.The workability,compressive and splitting strength,modulus of elasticity,restrained expansion and chloride ion permeability as well as freeze-thaw resistance of three MS-SCC mixes with fines content of 3%,7% and 10% were tested and compared with those of the natural sand （NS）-SCC mix.The experimental results indicate that the performances of the C60 MS-SCC with fines content of 7% are excellent and compared favorably with those of C60 NS-SCC.展开更多
Self-consolidating concrete(SCC)with manufactured sand(MSCC)is crucial to guarantee the quality of concrete construction technology and the associated property.The properties of MSCC with different microlimestone powd...Self-consolidating concrete(SCC)with manufactured sand(MSCC)is crucial to guarantee the quality of concrete construction technology and the associated property.The properties of MSCC with different microlimestone powder(MLS)replacements of retreated manufactured sand(TMsand)are investigated in this study.The result indicates that high-performance SCC,made using TMsand(TMSCC),achieved high workability,good mechanical properties,and durability by optimizing MLS content and adding fy ash and silica fume.In particular,the TMSCC with 12%MLS content exhibits the best workability,and the TMSCC with 4%MLS content has the highest strength in the late age,which is even better than that of SCC made with the river sand(R sand).Though MLS content slightly affects the hydration reaction of cement and mainly plays a role in the nucleation process in concrete structures compared to silica fume and fly ash,increasing MLS content can evidently have a significant impact on the early age hydration progress.TMsand with MLS content ranging from 8%to 12%may be a suitable alternative for the Rsand used in the SCC as fine aggregate.The obtained results can be used to promote the application of SCC made with manufactured sand and mineral admixtures for concrete-based infrastructure.展开更多
Introduction: Diabetic ulcers are one of the main causes of morbidity and hospitalisation and thereby affecting the quality of life of persons suffering from the condition. The aim of the study was to assess the level...Introduction: Diabetic ulcers are one of the main causes of morbidity and hospitalisation and thereby affecting the quality of life of persons suffering from the condition. The aim of the study was to assess the level of satisfaction of persons who underwent treatment for diabetic ulcers using negative pressure produced from locally available materials. Materials and Methods: Creating negative pressure using locally available materials such as sterilized foam, tubes with diameter between 0.5 and 0.8 cm, transparent adhesive plaster and a suction machine. Results: Thirty-seven patients were enrolled in the current study;70.3% (n = 26) were known diabetic patients on regular treatment while 29.7% (n = 11) were diagnosed when they presented for the first time with ulcers. Patients were made to grade their level of satisfaction with therapy involving these locally used materials. Out of the 37 patients, 35 (94.6%) stated their therapy was excellent while 1 (2.7%) said the therapy was good;therapy was discontinued in one patient (2.7%) who had some complication. Conclusion: Desirable outcomes were obtained when patients were treated using negative pressure wound therapy (NPWT) produced using locally manufactured materials. Patients were able to pay for the therapy since the cost was reasonably low.展开更多
A Raoult’s law-based screening-level assessment methodology was developed to calculate the carcinogenic and non-carcinogenic risks from ingestion of coal tar-contaminated water and it was applied to ten coal tars obt...A Raoult’s law-based screening-level assessment methodology was developed to calculate the carcinogenic and non-carcinogenic risks from ingestion of coal tar-contaminated water and it was applied to ten coal tars obtained from sites in the eastern United States. This approach provides a simple risk screening based on the conservative assumptions of Tier 1 in both the ASTM RBCA methodology and the USEPA Soil Screening Guidance. Results across the ten tars exhibited similar patterns, even though the coal tars had significantly different chemical compositions, and in all cases the screening-level risks were above the USEPA thresholds. There was no appreciable difference in the total risks when using either the current USEPA 1993 PAH risk assessment guidance or the proposed 2010 guidance. Benzene, while present at low concentrations within the coal tars, posed the dominant risk and strong correlations were observed with the benzene mole fraction.展开更多
The immersed boundary method is an effective technique for modeling and simulating fluid-structure interactions especially in the area of biomechanics.This paper analyzes the accuracy of the immersed boundary method.T...The immersed boundary method is an effective technique for modeling and simulating fluid-structure interactions especially in the area of biomechanics.This paper analyzes the accuracy of the immersed boundary method.The procedure contains two parts,i.e.,the code verification and the accuracy analysis.The code verification provides the confidence that the code used is free of mistakes,and the accuracy analysis gives the order of accuracy of the immersed boundary method.The method of manufactured solutions is taken as a means for both parts.In the first part,the numerical code employs a second-order discretization scheme,i.e.,it has second-order accuracy in theory.It matches the calculated order of accuracy obtained in the numerical calculation for all variables.This means that the code contains no mistake,which is a premise of the subsequent work.The second part introduces a jump in the manufactured solution for the pressure and adds the corresponding singular forcing terms in the momentum equations.By analyzing the discretization errors,the accuracy of the immersed boundary method is proven to be first order even though the discretization scheme is second order.It has been found that the coarser mesh may not be sensitive enough to capture the influence of the immersed boundary,and the refinement on the Lagrangian markers barely has any effect on the numerical calculation.展开更多
The accuracy of gradient reconstruction methods on unstructured meshes is analyzed both mathematically and numerically.Mathematical derivations reveal that,for gradient reconstruction based on the Green-Gauss theorem(...The accuracy of gradient reconstruction methods on unstructured meshes is analyzed both mathematically and numerically.Mathematical derivations reveal that,for gradient reconstruction based on the Green-Gauss theorem(the GG methods),if the summation of first-and-lower-order terms does not counterbalance in the discretized integral process,which rarely occurs,second-order accurate approximation of face midpoint value is necessary to produce at least first-order accurate gradient.However,gradient reconstruction based on the least-squares approach(the LSQ methods)is at least first-order on arbitrary unstructured grids.Verifications are performed on typical isotropic grid stencils by analyzing the relationship between the discretization error of gradient reconstruction and the discretization error of the face midpoint value approximation of a given analytic function.Meanwhile,the numerical accuracy of gradient reconstruction methods is examined with grid convergence study on typical isotropic grids.Results verify the phenomenon of accuracy degradation for the GG methods when the face midpoint value condition is not satisfied.The LSQ methods are proved to be at least first-order on all tested isotropic grids.To study gradient accuracy effects on inviscid flow simulation,solution errors are quantified using the Method of Manufactured Solutions(MMS)which was validated before adoption by comparing with an exact solution case,i.e.,the 2-dimensional(2D)inviscid isentropic vortex.Numerical results demonstrate that the order of accuracy(OOA)of gradient reconstruction is crucial in determining the OOA of numerical solutions.Solution accuracy deteriorates seriously if gradient reconstruction does not reach first-order.展开更多
A siliconizing process to manufacture 6.5% Si steel sheet has been developed. Electric components, such as transformers and reactors are made easily from 6.5% Si steel sheet. However, improved workability is desirable...A siliconizing process to manufacture 6.5% Si steel sheet has been developed. Electric components, such as transformers and reactors are made easily from 6.5% Si steel sheet. However, improved workability is desirable to increase the applications. Therefore the improvement of workability of 6.5% Si steel sheet was investigated, and the results were obtained as follows: (a) workability of 6.5% Si steel sheet is deteriorated by grain boundary oxidization, (b) grain boundary oxidization can be restrained by the addition of C. Workability and magnetic properties of 6.5% Si steel sheet with C addition are discussed. Furthermore, it was found that the workability of high Si steel sheet was improved remarkably by varying the Si content gradient along the thickness without deterioration of high frequency magnetic properties. This newly developed magnetic gradient high Si steel sheet is also discussed.展开更多
基金the financial support from China's Social Science Research Project(No.06CJL010 and No.08CJL025)Nankai University's 985 Research Innovation Project(No.985TNC20070202)the Social Science Large Grant Project(No.07JJD790137)supported by the Ministry of Education
文摘Using panel data for 29 provinces in China during 1990-2004, the present paper attempts to explore a possible link between financial development and China＇s foreign trade. Three measures of comparative advantage in manufactured goods have been applied in our study, including Balassa＇s revealed comparative advantage, the net manufactured export index, and the Michaely index. We also use four indicators of financial development to identify the different functions of regional financial development, and to determine both size and efficiency features of financial institutions. The estimation results suggest that besides factor endowments, foreign firms and infrastructure, financial development has a quantitatively large and robust effect on China ＇ s manufactured goods trade. Therefore, further reform of China＇s financial system should be encouraged to fully exploit the comparative advantage of China＇s foreign trade.
基金Funded by the National West Communication Construction Technology Project(No.2013 318 354 190)
文摘Six representative parent rocks of sand, including limestone, quartzite, gneisses, granite, Basalt and Marble were selected to conduct a systematical research on the effects of various lithologies of manufactured sand on the workability, mechanism properties, volume stability and durability of manufacturedsand concrete. The experimental results show that the strength of manufactured-sand concrete is slightly higher than that of natural-sand concrete. Furthermore, substituting 15% cement of the concrete mixture with equal quantity of the six different lithology stone powder respectively, the data indicated that they can improve the concrete’s workability, postpone the plastic cracking time, enhance the anti-cracking grade, and have no obvious effect on the properties of antifreeze and sulfate attack resistance but reduce the capability to resist chloride ion penetration. Moreover, the differences in concrete’s workability, mechanism properties, volume stability and durability caused by various lithologies of manufactured sand and stone powder were not significant and the influence of lithology variety on the macro properties of concrete could be neglected eventually.
基金Funded by the National West Communication Construction Technology Project(No.200731822301-6)
文摘The relation between the methylene blue （MB） value of MS and its limestone powder content and clay content was investigated. The effects of MB values ranging from 0.35 to 2.5 on the workability of fresh concrete, the mechanical properties, the resistance to freezing as well as the resistance to chlorine ion permeation of the hardened concrete were all investigated. The experimental results showed that the MB value had no correlation with the limestone powder content of MS, while it was directly related to the clay content. With an increase of MB value, concrete workability decreased, as did the flexural and 7-day compressive strengths, however, the 28-day compressive strength was not affected. Furthermore, influence of MB value on concretes of different strength levels was different. For low-strength concretes, an increase of MB value could improve its impermeability, but this was not the case for high-strength concretes. Instead, their resistance to chloride ion permeability decreased slightly. However, even a slight increase in MB value remarkably accelerated freeze-thaw damage of MS concrete. It was thus concluded that the critical MB value of 1.4 would not cause significant deterioration in the performance of MS concretes.
基金supported by the National Natural Science Foundation of China(No.51709097).
文摘River sand is an essential component used as a fine aggregate in mortar and concrete.Due to unrestrained exploitation,river sand resources are gradually being exhausted.This requires alternative solutions.This study deals with the properties of cement mortar containing different levels of manufactured sand(MS)based on quartzite,used to replace river sand.The river sand was replaced at 20%,40%,60%and 80%with MS(by weight or volume).The mechanical properties,transfer properties,and microstructure were examined and compared to a control group to study the impact of the replacement level.The results indicate that the compressive strength can be improved by increasing such a level.The strength was improved by 35.1%and 45.5%over that of the control mortar at replacement levels of 60%and 80%,respectively.Although there was a weak link between porosity and gas permeability in the mortars with manufactured sand,the gas permeability decreased with growing the replacement level.The microstructure of the MS mortar was denser,and the cement paste had fewer microcracks with increasing the replacement level.
基金Funded by the Nationd West Communication Construction Technology Project(No.200331881106)
文摘The relation between methylene blue （MB） value of MS and its limestone dust content and clay content was investigated. The effects of MB value ranging from 0.35 to 2.5 on the workability of fresh concrete and crack propagation characteristics at the age of 24 hours, and effects on the mechanical properties, dry shrinkage of the harden concrete were tested. The experimental results show that the MB value is not related with the limestone dust content of MS, but in direct proportion to clay content. With the increase of MB value, the concrete workability decreases, and the flexural strength and 7 d compressive strength reduce markedly, whearas the 28 d compressive strength is not affected. When the MB-value is less than or equal to 1.35, the change of the MB-value has a little influence on early plastic cracking and dry shrinkage property of concrete, but when the MB-value is more than 1.35, the tendency of plastic cracking and dry shrinkage is remarkable.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(grant No.XDB36000000)the National Basic Research Program of China(grant No.2020YFA0710702)the National Natural Science Foundation of China(grant Nos.51822207 and 51772292).
文摘Manufactured nanomaterials with unique properties have been extensively applied in various indus-trial,agricultural or medical fields.However,some of the properties have been identified to be closely related to nanomaterial toxicity.The"nano-paradox"has aroused concerns over the use and develop-ment of nanotechnology,which makes it difficult for regulatory agencies to regulate nanomaterials.The key to fulfilling proper nanomaterial regulation lies in the adequate understanding of the impact of nanomaterial properties on nano-bio interactions.To this end,we start the present work with a brief intro-duction to nano-bio interactions at different levels.Based on that,how key toxicity-associated properties of manufactured nanomaterials(i.e.,size,shape,chemical composition,surface properties,biocorona formation,agglomeration and/or aggregation state,and biodegradability)impact their toxicokinetics,cel-lular uptake,trafficking and responses,and toxicity mechanisms is deeply explored.Moreover,advanced analytical methods for studying nano-bio interactions are introduced.Furthermore,the current reg-ulatory and legislative frameworks for nanomaterial-containing products in different regions and/or countries are presented.Finally,we propose several challenges facing the nanotoxicology field and their possible solutions to shed light on the safety evaluation of nanomaterials.
基金National Natural Science Foundation of China(Nos.51405079)China Postdoctoral Science Foundation of China(No.2015M570307)+1 种基金the Fundamental Research Funds for the Central Universities,Chinathe Jiangsu Planned Projects for Postdoctoral Research Funds,China
文摘Compared with bar code and quick response( QR) code in the storage and retailing management of textiles, the ultra-high frequency( UHF) radio frequency identification( RFID) tags have high information capacity as well as reliability in complex environmental conditions. In this study,the UHF RFID tags with perfect integration with textiles are assembled with screen-printed antenna on woven water-mark nylon fabric and Alien UHF integrated circuit( IC), and their reading performance under various washing and bending conditions is evaluated by an RFID reader. The results show that the tags after fifty bending( both arch and sink) cycles of screen-printed antenna still have reading distance more than 5.5 m,and an average reading distance is over 4.0 m after five washing cycles. The experimental results demonstrate that the tag antenna on the water-mark fabric can be manufactured by the screen-printing technology,and a coating process on this fabric facilitates the reading performance and the resistance against complex mechanical impact.
基金Funded by the National Natural Science Foundation of China(Nos.U1934206 and 52108260)the Foundation of China Academy of Railway Science Corporation Limited(No.2020YJ049)。
文摘By the addition of superplasticizer and air entraining agent,manufactured sand selfcompacting concrete(MS SCC)with slump flow varying from 500 to 700 mm and air content varying from 2.0%to 9.0%were prepared and the pumpability of MS SCC was studied by a sliding pipe rheometer(Sliper).According to the Kaplan’s model,the initial pump pressure and the pump resistance of MS SCC were obtained.Meanwhile,rheological properties including the yield stress and the plastic viscosity of MS SCC were measured by a rheometer.The experimental results show that the increase of slump flow contributes to a higher pumpability and a proper air content,i e,6%is beneficial for the pumpability of MS SCC.Due to the existence of stone powder and stronger angularity of MS,the initial pump pressure of MS SCC is only about 60%-88%that of river sand(RS)SCC with the same slump flow and air content,indicating that MS SCC possesses a higher pumpability than RS SCC.
文摘A tremendous amount of non-biodegradable waste is created during mining and processing tasks of layered stones like marble.Over time,this has become a global problem because it harms the environment in multiple ways.Hence,it is necessary to find an alternate way to securely dispose and reuse marble wastes.The construction sector is one of the significant consumers of natural resources for the production of material binders and aggregates.As a result,in recent years,number of researchers have carried out studies in which various kinds of marble waste have been incorporated into concrete with the intention of substituting either cement or aggregates or both.This paper presents the effect of two locally sourced waste marble powders Kadapa marble powder(KMP)and Bethamcherla marble powder(BMP)as partial replacement of cement on mechanical and durability properties of high strength concrete(HSC).Their effect at different replacement levels in HSC is evaluated in compressive,indirect tensile and flexural strengths,elastic modulus,chloride penetration resistance and freeze-thaw durability properties.Micro-structural investigation is also conducted to evaluate their impact on the matrix of HSC containing waste marble powders as additional cementitious materials.Results show that the HSC consisting of KMP and BMP content of 10%and 15%,respectively exhibited higher mechanical and durability properties than the control HSC.Micro-structural investigation also supports this finding.It can be concluded that the use of marble powders as partial replacement of cement does not have any adverse impact on the properties of concrete.The use of KMP and BMP reduces the vast amount of energy required to produce cement,cost and time with reduction in environmental hazards.
基金Funded by National Natural Science Foundation of China(No.51372185)
文摘To better understand and assess the effect of microfines on concrete properties, the synergetic effect of methylene blue value and content of microfines on properties of low and high strength concrete was studied and then the relationships between the index of modified methylene blue value （MMBV） and concrete properties were investigated. The results show that relationships between MMBV and fresh and hardened properties of concrete can be fully established, and the correlation between MMBV and C60 concrete property is higher than the correlation between MMBV and C30 concrete. With the increase of MMBV, concrete workability and frost resistance decrease while drying shrinkage decreases; however, compressive strength and chloride-ion penetration resistance of C30 concrete have not been negatively affected whereas those of C60 concrete are significantly deteriorated when MMBV exceeds 100. To make use of microfines without remarkably damaging concrete quality, it is suggested that MMBV of microfines in MS used in C30 and C60 concrete be no more than 100.
基金supported by the National Natural Science Foundation of China(Nos.U1401249 and51375177)the Postdoctoral Science Foundation of China(Nos.2015T80904 and 2014M560659)the Fundamental Research Funds for the Central Universities
文摘To further improve the luminous efficiency of LED lightings,this Letter proposes a chip-on-board（COB）device by combining diced staggered V-shaped patterns and remote phosphors.The results show that the V-shaped patterned COB（V-COB）with vertex angles from 120o to 150o can achieve a～17%output power increase（OPI）compared to the conventional COB.V-COB remote phosphor devices（RPDs）are then manufactured and tested.The luminous efficiency of the proposed RPD represents an 11.6%increase at the correlated color temperature of～3000 K.Such an improvement can be attributed to both the decreases of total internal reflections and phosphor backscatterings.
基金an EPSRC grant(EP/H026290/1),awarded to PK,on nanoparticles dispersion invehicle wakes
文摘Recent Euro 5 and Euro 6 vehicle emission standards are the first ever initiative to control particles on a number basis at the source. Related standards are also desirable for ambient nanoparticles （taken in this article to be those below 300 rim） to protect against possible adverse effects on public health and the environment. However, there are a number of technical challenges that need to be tackled before developing a regulatory framework for atmospheric nanoparticles. Some of the challenges derive from a lack of standardisation of the key measurement parameters, including sampling, necessary for robust evaluation of particle number concentrations, especially in the context of insufficient knowledge of the physicochemical characteristics of emerging sources （i.e. bio-fuel derived and manufactured nanoparti- cles）. Ideally, ambient concentrations of primary particles could be linked to primary particle emissions by use of nanoparticle dispersion models, and secondary nanoparticles using photochemical modeling tools. The limitations in these areas are discussed. Although there is inadequate information on the exact biological mechanism through which these particles cause harm, it is argued that this should not in itself delay the introduction of regulation. This article reviews the missing links between the existing knowledge of nanoparticle number concentrations and the advances required to tackle the technical challenges implied in developing regulations.
基金Funded by the Science and Technology Item of Communication Construction for West China (No.2009318811082)
文摘To meet the requirements of construction of concretes filled in the steel tube arches,a C60 grade micro-expansive self-compacting concrete （SCC） was prepared from manufactured sand （MS）.The utilization of MS with a high content of quarry limestone fines was dealed for SCC applications.The workability,compressive and splitting strength,modulus of elasticity,restrained expansion and chloride ion permeability as well as freeze-thaw resistance of three MS-SCC mixes with fines content of 3%,7% and 10% were tested and compared with those of the natural sand （NS）-SCC mix.The experimental results indicate that the performances of the C60 MS-SCC with fines content of 7% are excellent and compared favorably with those of C60 NS-SCC.
基金All the authors appreciate the supports from the Australian Research Council(DEI50101751,IH150100006)University of Technology Sydney Research Academic Program at Tech Lab(UTS RAPT),University of Technology Sydney Tech Lab Blue Sky Research Scheme.
文摘Self-consolidating concrete(SCC)with manufactured sand(MSCC)is crucial to guarantee the quality of concrete construction technology and the associated property.The properties of MSCC with different microlimestone powder(MLS)replacements of retreated manufactured sand(TMsand)are investigated in this study.The result indicates that high-performance SCC,made using TMsand(TMSCC),achieved high workability,good mechanical properties,and durability by optimizing MLS content and adding fy ash and silica fume.In particular,the TMSCC with 12%MLS content exhibits the best workability,and the TMSCC with 4%MLS content has the highest strength in the late age,which is even better than that of SCC made with the river sand(R sand).Though MLS content slightly affects the hydration reaction of cement and mainly plays a role in the nucleation process in concrete structures compared to silica fume and fly ash,increasing MLS content can evidently have a significant impact on the early age hydration progress.TMsand with MLS content ranging from 8%to 12%may be a suitable alternative for the Rsand used in the SCC as fine aggregate.The obtained results can be used to promote the application of SCC made with manufactured sand and mineral admixtures for concrete-based infrastructure.
文摘Introduction: Diabetic ulcers are one of the main causes of morbidity and hospitalisation and thereby affecting the quality of life of persons suffering from the condition. The aim of the study was to assess the level of satisfaction of persons who underwent treatment for diabetic ulcers using negative pressure produced from locally available materials. Materials and Methods: Creating negative pressure using locally available materials such as sterilized foam, tubes with diameter between 0.5 and 0.8 cm, transparent adhesive plaster and a suction machine. Results: Thirty-seven patients were enrolled in the current study;70.3% (n = 26) were known diabetic patients on regular treatment while 29.7% (n = 11) were diagnosed when they presented for the first time with ulcers. Patients were made to grade their level of satisfaction with therapy involving these locally used materials. Out of the 37 patients, 35 (94.6%) stated their therapy was excellent while 1 (2.7%) said the therapy was good;therapy was discontinued in one patient (2.7%) who had some complication. Conclusion: Desirable outcomes were obtained when patients were treated using negative pressure wound therapy (NPWT) produced using locally manufactured materials. Patients were able to pay for the therapy since the cost was reasonably low.
文摘A Raoult’s law-based screening-level assessment methodology was developed to calculate the carcinogenic and non-carcinogenic risks from ingestion of coal tar-contaminated water and it was applied to ten coal tars obtained from sites in the eastern United States. This approach provides a simple risk screening based on the conservative assumptions of Tier 1 in both the ASTM RBCA methodology and the USEPA Soil Screening Guidance. Results across the ten tars exhibited similar patterns, even though the coal tars had significantly different chemical compositions, and in all cases the screening-level risks were above the USEPA thresholds. There was no appreciable difference in the total risks when using either the current USEPA 1993 PAH risk assessment guidance or the proposed 2010 guidance. Benzene, while present at low concentrations within the coal tars, posed the dominant risk and strong correlations were observed with the benzene mole fraction.
基金supported by the National Natural Science Foundation of China (No 10472070)
文摘The immersed boundary method is an effective technique for modeling and simulating fluid-structure interactions especially in the area of biomechanics.This paper analyzes the accuracy of the immersed boundary method.The procedure contains two parts,i.e.,the code verification and the accuracy analysis.The code verification provides the confidence that the code used is free of mistakes,and the accuracy analysis gives the order of accuracy of the immersed boundary method.The method of manufactured solutions is taken as a means for both parts.In the first part,the numerical code employs a second-order discretization scheme,i.e.,it has second-order accuracy in theory.It matches the calculated order of accuracy obtained in the numerical calculation for all variables.This means that the code contains no mistake,which is a premise of the subsequent work.The second part introduces a jump in the manufactured solution for the pressure and adds the corresponding singular forcing terms in the momentum equations.By analyzing the discretization errors,the accuracy of the immersed boundary method is proven to be first order even though the discretization scheme is second order.It has been found that the coarser mesh may not be sensitive enough to capture the influence of the immersed boundary,and the refinement on the Lagrangian markers barely has any effect on the numerical calculation.
基金National Natural Science Foundation of China[grant numbers 11532016,91530325].
文摘The accuracy of gradient reconstruction methods on unstructured meshes is analyzed both mathematically and numerically.Mathematical derivations reveal that,for gradient reconstruction based on the Green-Gauss theorem(the GG methods),if the summation of first-and-lower-order terms does not counterbalance in the discretized integral process,which rarely occurs,second-order accurate approximation of face midpoint value is necessary to produce at least first-order accurate gradient.However,gradient reconstruction based on the least-squares approach(the LSQ methods)is at least first-order on arbitrary unstructured grids.Verifications are performed on typical isotropic grid stencils by analyzing the relationship between the discretization error of gradient reconstruction and the discretization error of the face midpoint value approximation of a given analytic function.Meanwhile,the numerical accuracy of gradient reconstruction methods is examined with grid convergence study on typical isotropic grids.Results verify the phenomenon of accuracy degradation for the GG methods when the face midpoint value condition is not satisfied.The LSQ methods are proved to be at least first-order on all tested isotropic grids.To study gradient accuracy effects on inviscid flow simulation,solution errors are quantified using the Method of Manufactured Solutions(MMS)which was validated before adoption by comparing with an exact solution case,i.e.,the 2-dimensional(2D)inviscid isentropic vortex.Numerical results demonstrate that the order of accuracy(OOA)of gradient reconstruction is crucial in determining the OOA of numerical solutions.Solution accuracy deteriorates seriously if gradient reconstruction does not reach first-order.
文摘A siliconizing process to manufacture 6.5% Si steel sheet has been developed. Electric components, such as transformers and reactors are made easily from 6.5% Si steel sheet. However, improved workability is desirable to increase the applications. Therefore the improvement of workability of 6.5% Si steel sheet was investigated, and the results were obtained as follows: (a) workability of 6.5% Si steel sheet is deteriorated by grain boundary oxidization, (b) grain boundary oxidization can be restrained by the addition of C. Workability and magnetic properties of 6.5% Si steel sheet with C addition are discussed. Furthermore, it was found that the workability of high Si steel sheet was improved remarkably by varying the Si content gradient along the thickness without deterioration of high frequency magnetic properties. This newly developed magnetic gradient high Si steel sheet is also discussed.
