Interactions between different components in α-starch based composite binder for green sand mould/core were investigated by using XRD, IR spectra, 1H NMR spectra and SEM. Several adhesive hardening structures and the...Interactions between different components in α-starch based composite binder for green sand mould/core were investigated by using XRD, IR spectra, 1H NMR spectra and SEM. Several adhesive hardening structures and theories of the binder at room temperature were proposed according to the interactions between various compositions. Thus, the reasons for the binder to have excellent combination properties and unique adhesive bonding and self-curing characteristics were explained by these theories successfully. And the theories are of great directive importance to design and development of composite binder for green sand mould/core.展开更多
In the measurement of damping material's dynamic mechanical performance(DMP) using flexural resonating cantilever beam method,the specimen's adhesive characteristic influences the test precision and accuracy. ...In the measurement of damping material's dynamic mechanical performance(DMP) using flexural resonating cantilever beam method,the specimen's adhesive characteristic influences the test precision and accuracy. Taking its effect into account,the improved measurement equations based on the resonance method are presented. The simulated results show that,for the sake of weakening the adhesive's influence on the measured results,the adhesive should be spreaded as thin as possible when specimen is prepared,the adhesive's density and loss factor should be selected as small as possible also,and its Young's modulus should be selected according to the damping material being measured;the same adhesion condition effects differently on the test results of different damping materials,i.e. the error due to the adhesive is more inconspicuous if the damping layer has bigger thickness,modulus,loss factor and a certain density according to the damping material being measured. These conclusions provide theoretical basis for selecting adhesive,improving adhesion technology,and designing specimen.展开更多
The surface energy characteristics of uncoated (clean) and coated stainless steel with UHT milk at various contact time (5 min, 30 min, 1 hours, 3 hours, 6 hours, 24 hours) were determined using contact angle measurem...The surface energy characteristics of uncoated (clean) and coated stainless steel with UHT milk at various contact time (5 min, 30 min, 1 hours, 3 hours, 6 hours, 24 hours) were determined using contact angle measurement. Whatever the contact time, the clean stainless steel coupons became more hydrophobic and more electron acceptor when they are coated by milk. Inversely, the electron donor character seems to decreasing in this condition. The calculated surface energy component of coated stainless steel was found to vary with contact time. Its hydrophobicity and its electron acceptor were minimal after 3 hours of contact, but its electron donor was minimal after 1 hours of contact. Adhesion experiments of Staphylococcus aureus were carried out on uncoated and coated stainless steels at various contact times. For all contact times, the adhesion results show that milk reduce S. aureus adhesion, and the level of this reduction depend on contact time. This reduction was lower and higher after 1 hours, 5 min and 30 min of contact respectively.展开更多
Initial bacterial adhesion on dental implant abutment is related to its surface chemical composition and physical characteristics.Selection of appropriate abutment materials resistant to bacterial adhesion is importan...Initial bacterial adhesion on dental implant abutment is related to its surface chemical composition and physical characteristics.Selection of appropriate abutment materials resistant to bacterial adhesion is important for dental implant maintenance.The aim of present study was to evaluate the effect of different properties of abutment materials on initial bacterial adhesion in vitro.Polished zirconia(PZ group), polished titanium(PT group) and ground titanium(GT group) samples were prepared to simulate clinical dental implant abutments.Chemical compositions, morphology, roughness, hydrophilicity and surface free energy of materials were analyzed.Oral commensal bacterium Streptococcus mitis was used to evaluate initial bacterial adhesion via turbidity test and colony-forming unit counting.The results showed that GT group presented the highest roughness, hydrophilicity and surface free energy.After 6-h incubation, GT group showed the significantly highest adhered bacteria counts;while non-significant difference existed between PT and PZ groups.Within the clinically applicable range used in present study, the surface physical characteristics, instead of surface chemical composition, of dental abutment material have the pronounced influence on initial 6-h bacterial adhesion.展开更多
Aluminum foam is widely used in diverse areas to minimize the weight and maximize the absorption of shock energy in lightweight structures and various bio-materials.It presents a number of advantages,such as low densi...Aluminum foam is widely used in diverse areas to minimize the weight and maximize the absorption of shock energy in lightweight structures and various bio-materials.It presents a number of advantages,such as low density,incombustibility,non-rigidity,excellent energy absorptivity,sound absorptivity and low heat conductivity.The aluminum foam with an air cell structure was placed under the TDCB Mode II tensile load by using Landmark equipment manufactured by MTS to examine the shear failure behavior.The angle of the tapered adhesively-bonded surfaces of specimens was designated as a variable,and three models were developed with the inclined angles differing from one another at 6°,8° and 10°.The specimens with the inclined angles of 6°,8° and 10° have the maximum reaction forces of 168 N,194 N when the forced displacements are 6,5 and 4.2 mm respectively.There are three specimens with the inclined angles of 10°,8° and 6° in the order of maximum reaction force.As the analysis result,the maximum equivalent stresses of 0.813 MPa and 0.895 MPa happened when the forced displacements of 6 mm and 5 mm proceeded at the models of 6° and 8°,respectively.A simulation was carried out on the basis of finite element method and the experimental design.The results of the experiment and the simulation analysis are shown not different from each other significantly.Thus,only a simulation could be confirmed to be performed in substitution of an experiment,which is costly and time-consuming in order to determine the shearing properties of materials made of aluminum foam with artificial data.展开更多
基金This work was supported by the China Postdoctoral Science Foundation(China Fund[1998]6)that was entitled“Synthesis of Modified Starch Binder and Its Application in Foundry”.Authors would like to thank academician Jinzong YANG and lecturer Hua ZHANG for the kind analyses and discussions.
文摘Interactions between different components in α-starch based composite binder for green sand mould/core were investigated by using XRD, IR spectra, 1H NMR spectra and SEM. Several adhesive hardening structures and theories of the binder at room temperature were proposed according to the interactions between various compositions. Thus, the reasons for the binder to have excellent combination properties and unique adhesive bonding and self-curing characteristics were explained by these theories successfully. And the theories are of great directive importance to design and development of composite binder for green sand mould/core.
基金Sponsored by the New Century Excellent Talent Project(NCET-06-0883)
文摘In the measurement of damping material's dynamic mechanical performance(DMP) using flexural resonating cantilever beam method,the specimen's adhesive characteristic influences the test precision and accuracy. Taking its effect into account,the improved measurement equations based on the resonance method are presented. The simulated results show that,for the sake of weakening the adhesive's influence on the measured results,the adhesive should be spreaded as thin as possible when specimen is prepared,the adhesive's density and loss factor should be selected as small as possible also,and its Young's modulus should be selected according to the damping material being measured;the same adhesion condition effects differently on the test results of different damping materials,i.e. the error due to the adhesive is more inconspicuous if the damping layer has bigger thickness,modulus,loss factor and a certain density according to the damping material being measured. These conclusions provide theoretical basis for selecting adhesive,improving adhesion technology,and designing specimen.
文摘The surface energy characteristics of uncoated (clean) and coated stainless steel with UHT milk at various contact time (5 min, 30 min, 1 hours, 3 hours, 6 hours, 24 hours) were determined using contact angle measurement. Whatever the contact time, the clean stainless steel coupons became more hydrophobic and more electron acceptor when they are coated by milk. Inversely, the electron donor character seems to decreasing in this condition. The calculated surface energy component of coated stainless steel was found to vary with contact time. Its hydrophobicity and its electron acceptor were minimal after 3 hours of contact, but its electron donor was minimal after 1 hours of contact. Adhesion experiments of Staphylococcus aureus were carried out on uncoated and coated stainless steels at various contact times. For all contact times, the adhesion results show that milk reduce S. aureus adhesion, and the level of this reduction depend on contact time. This reduction was lower and higher after 1 hours, 5 min and 30 min of contact respectively.
基金financially supported by the National Yang-Ming University Hospital (Nos.RD 2011-009, RD 2012-021 and RD 2013-013), Taiwan
文摘Initial bacterial adhesion on dental implant abutment is related to its surface chemical composition and physical characteristics.Selection of appropriate abutment materials resistant to bacterial adhesion is important for dental implant maintenance.The aim of present study was to evaluate the effect of different properties of abutment materials on initial bacterial adhesion in vitro.Polished zirconia(PZ group), polished titanium(PT group) and ground titanium(GT group) samples were prepared to simulate clinical dental implant abutments.Chemical compositions, morphology, roughness, hydrophilicity and surface free energy of materials were analyzed.Oral commensal bacterium Streptococcus mitis was used to evaluate initial bacterial adhesion via turbidity test and colony-forming unit counting.The results showed that GT group presented the highest roughness, hydrophilicity and surface free energy.After 6-h incubation, GT group showed the significantly highest adhered bacteria counts;while non-significant difference existed between PT and PZ groups.Within the clinically applicable range used in present study, the surface physical characteristics, instead of surface chemical composition, of dental abutment material have the pronounced influence on initial 6-h bacterial adhesion.
基金Project(2011-0006548)supported by Basic Science Research Program through the National Research Foundation of Korea
文摘Aluminum foam is widely used in diverse areas to minimize the weight and maximize the absorption of shock energy in lightweight structures and various bio-materials.It presents a number of advantages,such as low density,incombustibility,non-rigidity,excellent energy absorptivity,sound absorptivity and low heat conductivity.The aluminum foam with an air cell structure was placed under the TDCB Mode II tensile load by using Landmark equipment manufactured by MTS to examine the shear failure behavior.The angle of the tapered adhesively-bonded surfaces of specimens was designated as a variable,and three models were developed with the inclined angles differing from one another at 6°,8° and 10°.The specimens with the inclined angles of 6°,8° and 10° have the maximum reaction forces of 168 N,194 N when the forced displacements are 6,5 and 4.2 mm respectively.There are three specimens with the inclined angles of 10°,8° and 6° in the order of maximum reaction force.As the analysis result,the maximum equivalent stresses of 0.813 MPa and 0.895 MPa happened when the forced displacements of 6 mm and 5 mm proceeded at the models of 6° and 8°,respectively.A simulation was carried out on the basis of finite element method and the experimental design.The results of the experiment and the simulation analysis are shown not different from each other significantly.Thus,only a simulation could be confirmed to be performed in substitution of an experiment,which is costly and time-consuming in order to determine the shearing properties of materials made of aluminum foam with artificial data.
