To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release...To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment,which increased their warpage.TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature.The warpage of Type E increased by 155.88%and 66.67%in the width and diagonal directions,respectively,when the temperature increased from 25C to 100C.The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability.We revealed that the deformation of the TBLCs could be regulated under the synergistic effect of water and temperature.These results provide a scientific basis for improving the uniformity of bamboo bundle composite materials and for developing thin bamboo bundle fiber composite materials with designable structures and controllable performance.展开更多
Equilibrium isotope fractionation of thallium(Tl) includes the traditional mass-dependent isotope fractionation effect and the nuclear volume effect(NVE). The NVE dominates the overall isotope fractionation, especiall...Equilibrium isotope fractionation of thallium(Tl) includes the traditional mass-dependent isotope fractionation effect and the nuclear volume effect(NVE). The NVE dominates the overall isotope fractionation, especially at high temperatures. Heavy Tl isotopes tend to be enriched in oxidized Tl^3+-bearing species. Our NVE fractionation results of oxidizing Tl^+ to Tl^3+ can explain the positive enrichments observed in ferromanganese sediments. Experimental results indicate that there could be0.2–0.3 e-unit fractionation between sulfides and silicates at 1650 ℃. It is consistent with our calculation results,which are in the range of 0.17–0.38 e-unit. Importantly,Tl’s concentration in the bulk silicate Earth(BSE) can be used to constrain the amount of materials delivered to Earth during the late veneer accretion stage. Because the Tl concentration in BSE is very low and its Tl isotope composition is similar with that of chondrites, suggesting either no Tl isotope fractionation occurred during numerous evaporation events, or the Tl in current BSE was totally delivered by late veneer. If it is the latter, the Tl-contentbased estimation could challenge the magnitude of late veneer which had been constrained by the amount of highly siderophile elements in BSE. Our results show that the lateaccreted mass is at least five-times larger than the previously suggested magnitude, i.e., 0.5 wt% of current Earth’s mass. The slightly lighter 205 Tl composition of BSE relative to chondrites is probable a sign of occurrence of Tlbearing sulfides, which probably were removed from the mantle in the last accretion stage of the Earth.展开更多
Porcelain laminate veneers have been a common treatment strategy in dental clinics. It is a conservative method for treatment of esthetic and functional problems in anterior region of oral cavity. Wide range of dental...Porcelain laminate veneers have been a common treatment strategy in dental clinics. It is a conservative method for treatment of esthetic and functional problems in anterior region of oral cavity. Wide range of dental ceramics is now available on market for fabrication of laminate veneers. Clinician should have enough knowledge regarding the composition and properties of these materials in order to be able to choose the appropriate one according to clinical situations.展开更多
Objective:To evaluate the shear bond strength(SBS) between alumina-toughened zirconia (ATZ) cores and veneering ceramics,investigate the effect of aging in artificial saliva on SBS and compare it with that of yttria-s...Objective:To evaluate the shear bond strength(SBS) between alumina-toughened zirconia (ATZ) cores and veneering ceramics,investigate the effect of aging in artificial saliva on SBS and compare it with that of yttria-stabilized tetragonal zirconia polycrystals(Y-TZP).Methods:Bars of ATZ and Y-TZP were layered with veneering ceramics in accordance to the recommendation of the manufacturer.Half of each group(n = 10) was aged at 134℃.(under 2 bar pressure) in an autoclave for 48 h.Subsequently,all specimens were subjected to shear force in a universal testing machine.The interface and fractured surface of the specimens were evaluated using scanning electron microscopy and X-ray energy dispersive spectroscopy.Results:The initial mean SBS values in MPa±SD were 28.9±8.0 for ATZ and 26.2±7.6 for Y-TZP.After aging,the mean SBS values for ATZ and Y-TZP were 22.9±4.9 MPa and 22.8±6.9 MPa,respectively.Neither the differences between the SBS values of the ATZ and Y-TZP groups nor the influence of aging on all groups were statistically significant.Conclusions:The SBS between the ATZ core and the veneering ceramics was not affected by aging.The SBS of ATZ to veneering ceramics was not significantly different compared with that of Y-TZP.展开更多
This paper, with veneer as a particularly detected target, deals with a new method for detecting veneer moisture content. Surface resistance is measured by the fixed pressure, circle-shaped point and surface-touched d...This paper, with veneer as a particularly detected target, deals with a new method for detecting veneer moisture content. Surface resistance is measured by the fixed pressure, circle-shaped point and surface-touched detector. With the help of the computer, the veneer moisture and its distribution will be detected in a faster way with no harm to the veneer surface.展开更多
Late veneer is an important paradigm in early Earth and planetary studies.It refers to the late addition of extraterrestrial materials to the Earth’s mantle after the core formation,which leads to the overabundances ...Late veneer is an important paradigm in early Earth and planetary studies.It refers to the late addition of extraterrestrial materials to the Earth’s mantle after the core formation,which leads to the overabundances of highly siderophile elements in the primitive upper mantle.In this review,the origin,evolution,and expansion of the late veneer hypothesis are summarized,including some unresolved problems.I hope this review would be helpful for the new entrants to this field.展开更多
Based on the LOM(Laminated Object Manufacturing)process,an inert gas-assisted laser method for wood cutting was proposed.The carbonization degree of wood surface was improved by the introduction of helium(He)gas,and t...Based on the LOM(Laminated Object Manufacturing)process,an inert gas-assisted laser method for wood cutting was proposed.The carbonization degree of wood surface was improved by the introduction of helium(He)gas,and the influence of process parameters on the carbonization layer of wood surface was solved,it was significance to reduce the post-processing of LOM and improve the quality of forming workpiece.The cherry wood veneer was used as the experimental material,under the condition of the same process parameters,the wood was cut with or without inert gas-assisted,and the influence factors of kerf quality were studied by variance analysis.The results showed that under the same condition,compared with traditional laser processing,the kerf width was obviously reduced in the inert gas-assisted cutting.Because the He gas had oxygen-isolation and flame retardant effect,which prevented heat accumulation and conduction.The micro morphology of the kerf surface showed that the flatness was better in the inert gas-assisted cutting.As the excess heat was blown out by the cooling and purging of the gas,the phenomenon of oxidation and burning was reduced,the range of HAZ(heat affected zone)was reduced,and the carbonization phenomenon was obviously improved.The surface quality of kerf was improved effectively.According to the analysis of variance,in addition to the effect of laser power,cutting speed and inert gas flow on the cutting width,the interaction between inert gas flow and laser power,laser power and cutting speed were also the main factors which affected the cutting width.The feasibility of the combined inert gas and laser processing to improve wood cutting quality has been verified through experimental research,which provided a certain reference for the followup research on improving the wood processing quality.展开更多
A system of finished Componeer composite veneers is a unique and having no analogy in the world elaboration of the Swisscompany Coltene/Whaledent, an outcome of almost halfa century experience of the company working i...A system of finished Componeer composite veneers is a unique and having no analogy in the world elaboration of the Swisscompany Coltene/Whaledent, an outcome of almost halfa century experience of the company working in a field of composite materials.It combines the best features of direct and indirect restoration methods. The system is fulfilled of nanocomposite Synergy D6 that hashigh mechanical strength, convenience for workable consistency, color stability and a system of halftone shades, which facilitates colormatching. All this allows achieving excellent aesthetic results in minimal time. Application of an original standard scale givespossibility effectively assess optical properties of dental hard tissues and develop an implementation strategy of restoration before workstarted. Formation of Componeer form, polymerization and polishing at factory allow a practitioner fully utilize effect of＂fluorescence＂ inherent to the material. All this allows us to position the Componeer system as a serious alternative to non-directmethods of restoration with the possibility of both high aesthetic and cosmetic reconstruction reliability.展开更多
This paper discusses the performance of a proposed panelized brick veneer over steel stud backup wall system and seismic isolation connections under lateral loads. The panelized wall system was developed to address so...This paper discusses the performance of a proposed panelized brick veneer over steel stud backup wall system and seismic isolation connections under lateral loads. The panelized wall system was developed to address some shortcomings of the conventional brick veneer wall type. The details of the system are briefly introduced. The study evaluated the performance of the system under out-of-plane simulated wind loads and in-plane cyclic loads using full-scale laboratory experiments. The test setup, test specimen, test procedure, and test results are presented and the performance of the system is evaluated accordingly.展开更多
A newly drying technology, intermittent-contact drying of veneer with flexible screen belt (ICD-fbs), was invented and used in poplar veneer drying. Productive test was carried out for validating the practical use of ...A newly drying technology, intermittent-contact drying of veneer with flexible screen belt (ICD-fbs), was invented and used in poplar veneer drying. Productive test was carried out for validating the practical use of this drying method. The test result shows that to dispose flexible screen belts on the two sides of hot board could help steam discharge remarkably. The veneer dried using ICD-fsb method had smooth and level surface, less deformation and warping, even moisture content, and high utilization rate. The time for opening hot board to discharge steam,which, early or late, is a key to obtain good drying result, was determined at the time when the core's temperature of veneer reaches 100℃ (vaporization). Using ICD-fsb method, the shrinking rates in tangent of veneer were from 1.90% to 2.26% for veneer of 0.4 mm in thickness,2.49% to 4.50% for veneer of 1 mm in thickness and 1.34% to 3.30% for veneer of 1.7 mm in thickness, which are much lower than the results obtained by other drying methods. The method of ICD-fsb offers a reliable technological guarantee for solving the deformation problem of veneer drying, especially the deformation of wood from quick-growing plantation.展开更多
In an effort to find suitable wood from natural forest to meet the demand for veneer products, the yield and tensile strength of veneers produced from Brachystegia nigerica were investigated. Two trees of B. nigerica ...In an effort to find suitable wood from natural forest to meet the demand for veneer products, the yield and tensile strength of veneers produced from Brachystegia nigerica were investigated. Two trees of B. nigerica were separately selected from 10 different natural forest zones while two logs were obtained from each tree. The logs were debarked and steamed in a vat prior to rotary peeling and slicing for veneer production. The optimum steam temperature was determined by considering different temperatures: 50°C, 60°C, 70°C, 80°C and 90°C for 24 h. Thereafter, optimum steam time was determined at the optimum temperature by considering durations of 24, 48, 72 and 96 h. The average taper of 0.75 mm per 1.0 m length was recorded for B. nigerica, indicating that the logs were reasonably cylindrical; thereby its logs are good for the production of veneer. The yield ranged from 44% to 61% with an average of 52% of the log input. The tensile strength of the veneer was tested perpendicular to grain and both peeled and sliced veneers had the highest tensile strength between 70°C and 90°C, suggesting that softening of wood polymers, especially lignin, is between 70°C and 90°C. The optimum temperature and time for veneer production are 70°C and 48 h, respectively. Commercial production of veneer from B. nigerica is feasible based on the yield and mechanical properties of the obtained veneer, thereby encouraging the expansion of the scope ofits utilization.展开更多
Objective :To evaluale the color change of the two-layer porcelain laminate veneer after adding veneering porcelain of differeat thickness to the 0.2mm thick aluminum oxide.Methods:Ten alumium axide disks were randomi...Objective :To evaluale the color change of the two-layer porcelain laminate veneer after adding veneering porcelain of differeat thickness to the 0.2mm thick aluminum oxide.Methods:Ten alumium axide disks were randomized into 2 groups.Each of five disks was veneered with Vita Lumin Shade B4 porcelain of thickness of 0.4mm and 0.6mm respectively.The L*a*b* color notations of the substrate covered with non-veneered disks and 2 thickness porcelain veneered disks were measured separtely and the color differences(ΔE) were calculated.Results:Statistically significant differences in color coordinates of dark substrates were recorded after the sustrate was covered by an aluminum oxide disk and also after the addition of veneering porcelain to the alumimum axide disks in group 1(P=0.0002) and group 2(P=0.0075) and between 2 groups(P=0.0001).Conclusion:The ability of masking underlying discoloration was increased and shifted to gray when the thickness of veneering porcelain increased.展开更多
The discoloration of Scot pine （Pinus sylvestris var. Mongolica） veneers caused by resin-eliminated treatment and the reversion of the color were studied. The result showed that the color of the veneers changed from...The discoloration of Scot pine （Pinus sylvestris var. Mongolica） veneers caused by resin-eliminated treatment and the reversion of the color were studied. The result showed that the color of the veneers changed from buff to yellowish brown after the treatment of resin elimination and the discoloration of heartwood was more severe than that of sapwood; the degree of discoloration was significantly positively correlated with the medicament strength, temperature and resin-eliminated duration. The variance analysis showed the effects of those three factors on the discoloration were significant. With hydrogen peroxide （H2O2） as color reversion medicament and inorganic compound as medium of the reaction, the reversion of the color of heartwood was more inaccessible than that of sapwood; the degree of the color’s reversion was positively correlated with the H2O2 strength, temperature and treating time; the H2O2 concentration has significant effects on the discoloration. In order to reduce discoloration of Scot pine veneers, medicament of resin-eliminated used have to be at some low concentration, and the optimal concentration of H2O2 is 0.35% during the process of color’s reversion.展开更多
The stress-strain relation of laminated veneer lumber (LVL) was established by the method of regression, and its constitutive equation at large deformation and constant loading conditions was given to predict the stat...The stress-strain relation of laminated veneer lumber (LVL) was established by the method of regression, and its constitutive equation at large deformation and constant loading conditions was given to predict the static mechanical behaviors of LVL.展开更多
基金supported by the Youth Top-notch Talent Program of Science and Technology Innovation for Forestry and Grassland(2019132606).
文摘To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment,which increased their warpage.TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature.The warpage of Type E increased by 155.88%and 66.67%in the width and diagonal directions,respectively,when the temperature increased from 25C to 100C.The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability.We revealed that the deformation of the TBLCs could be regulated under the synergistic effect of water and temperature.These results provide a scientific basis for improving the uniformity of bamboo bundle composite materials and for developing thin bamboo bundle fiber composite materials with designable structures and controllable performance.
基金the funding supports from the strategic priority research program (B) of CAS (XDB18010100)Chinese NSF projects (Nos. 41530210, 41490635)
文摘Equilibrium isotope fractionation of thallium(Tl) includes the traditional mass-dependent isotope fractionation effect and the nuclear volume effect(NVE). The NVE dominates the overall isotope fractionation, especially at high temperatures. Heavy Tl isotopes tend to be enriched in oxidized Tl^3+-bearing species. Our NVE fractionation results of oxidizing Tl^+ to Tl^3+ can explain the positive enrichments observed in ferromanganese sediments. Experimental results indicate that there could be0.2–0.3 e-unit fractionation between sulfides and silicates at 1650 ℃. It is consistent with our calculation results,which are in the range of 0.17–0.38 e-unit. Importantly,Tl’s concentration in the bulk silicate Earth(BSE) can be used to constrain the amount of materials delivered to Earth during the late veneer accretion stage. Because the Tl concentration in BSE is very low and its Tl isotope composition is similar with that of chondrites, suggesting either no Tl isotope fractionation occurred during numerous evaporation events, or the Tl in current BSE was totally delivered by late veneer. If it is the latter, the Tl-contentbased estimation could challenge the magnitude of late veneer which had been constrained by the amount of highly siderophile elements in BSE. Our results show that the lateaccreted mass is at least five-times larger than the previously suggested magnitude, i.e., 0.5 wt% of current Earth’s mass. The slightly lighter 205 Tl composition of BSE relative to chondrites is probable a sign of occurrence of Tlbearing sulfides, which probably were removed from the mantle in the last accretion stage of the Earth.
文摘Porcelain laminate veneers have been a common treatment strategy in dental clinics. It is a conservative method for treatment of esthetic and functional problems in anterior region of oral cavity. Wide range of dental ceramics is now available on market for fabrication of laminate veneers. Clinician should have enough knowledge regarding the composition and properties of these materials in order to be able to choose the appropriate one according to clinical situations.
基金supported by National High-Tech Research and Development Program of China(863 Program)(No.2006AA03Z440)
文摘Objective:To evaluate the shear bond strength(SBS) between alumina-toughened zirconia (ATZ) cores and veneering ceramics,investigate the effect of aging in artificial saliva on SBS and compare it with that of yttria-stabilized tetragonal zirconia polycrystals(Y-TZP).Methods:Bars of ATZ and Y-TZP were layered with veneering ceramics in accordance to the recommendation of the manufacturer.Half of each group(n = 10) was aged at 134℃.(under 2 bar pressure) in an autoclave for 48 h.Subsequently,all specimens were subjected to shear force in a universal testing machine.The interface and fractured surface of the specimens were evaluated using scanning electron microscopy and X-ray energy dispersive spectroscopy.Results:The initial mean SBS values in MPa±SD were 28.9±8.0 for ATZ and 26.2±7.6 for Y-TZP.After aging,the mean SBS values for ATZ and Y-TZP were 22.9±4.9 MPa and 22.8±6.9 MPa,respectively.Neither the differences between the SBS values of the ATZ and Y-TZP groups nor the influence of aging on all groups were statistically significant.Conclusions:The SBS between the ATZ core and the veneering ceramics was not affected by aging.The SBS of ATZ to veneering ceramics was not significantly different compared with that of Y-TZP.
文摘This paper, with veneer as a particularly detected target, deals with a new method for detecting veneer moisture content. Surface resistance is measured by the fixed pressure, circle-shaped point and surface-touched detector. With the help of the computer, the veneer moisture and its distribution will be detected in a faster way with no harm to the veneer surface.
基金supported by NSFC 41703019Strategic Priority ResearchProgram(B)(XDB41000000)CDUT 10912-KYQD2020-08294。
文摘Late veneer is an important paradigm in early Earth and planetary studies.It refers to the late addition of extraterrestrial materials to the Earth’s mantle after the core formation,which leads to the overabundances of highly siderophile elements in the primitive upper mantle.In this review,the origin,evolution,and expansion of the late veneer hypothesis are summarized,including some unresolved problems.I hope this review would be helpful for the new entrants to this field.
基金The research was supported by Significant special research and development project of Guangdong province(2020B020216001)Fundamental Research Funds for the Central Universities(2572018CG06).
文摘Based on the LOM(Laminated Object Manufacturing)process,an inert gas-assisted laser method for wood cutting was proposed.The carbonization degree of wood surface was improved by the introduction of helium(He)gas,and the influence of process parameters on the carbonization layer of wood surface was solved,it was significance to reduce the post-processing of LOM and improve the quality of forming workpiece.The cherry wood veneer was used as the experimental material,under the condition of the same process parameters,the wood was cut with or without inert gas-assisted,and the influence factors of kerf quality were studied by variance analysis.The results showed that under the same condition,compared with traditional laser processing,the kerf width was obviously reduced in the inert gas-assisted cutting.Because the He gas had oxygen-isolation and flame retardant effect,which prevented heat accumulation and conduction.The micro morphology of the kerf surface showed that the flatness was better in the inert gas-assisted cutting.As the excess heat was blown out by the cooling and purging of the gas,the phenomenon of oxidation and burning was reduced,the range of HAZ(heat affected zone)was reduced,and the carbonization phenomenon was obviously improved.The surface quality of kerf was improved effectively.According to the analysis of variance,in addition to the effect of laser power,cutting speed and inert gas flow on the cutting width,the interaction between inert gas flow and laser power,laser power and cutting speed were also the main factors which affected the cutting width.The feasibility of the combined inert gas and laser processing to improve wood cutting quality has been verified through experimental research,which provided a certain reference for the followup research on improving the wood processing quality.
文摘A system of finished Componeer composite veneers is a unique and having no analogy in the world elaboration of the Swisscompany Coltene/Whaledent, an outcome of almost halfa century experience of the company working in a field of composite materials.It combines the best features of direct and indirect restoration methods. The system is fulfilled of nanocomposite Synergy D6 that hashigh mechanical strength, convenience for workable consistency, color stability and a system of halftone shades, which facilitates colormatching. All this allows achieving excellent aesthetic results in minimal time. Application of an original standard scale givespossibility effectively assess optical properties of dental hard tissues and develop an implementation strategy of restoration before workstarted. Formation of Componeer form, polymerization and polishing at factory allow a practitioner fully utilize effect of＂fluorescence＂ inherent to the material. All this allows us to position the Componeer system as a serious alternative to non-directmethods of restoration with the possibility of both high aesthetic and cosmetic reconstruction reliability.
文摘This paper discusses the performance of a proposed panelized brick veneer over steel stud backup wall system and seismic isolation connections under lateral loads. The panelized wall system was developed to address some shortcomings of the conventional brick veneer wall type. The details of the system are briefly introduced. The study evaluated the performance of the system under out-of-plane simulated wind loads and in-plane cyclic loads using full-scale laboratory experiments. The test setup, test specimen, test procedure, and test results are presented and the performance of the system is evaluated accordingly.
基金This work is supported by "Xing Huo" Program of the Ministry of Agriculture, P. R. China.
文摘A newly drying technology, intermittent-contact drying of veneer with flexible screen belt (ICD-fbs), was invented and used in poplar veneer drying. Productive test was carried out for validating the practical use of this drying method. The test result shows that to dispose flexible screen belts on the two sides of hot board could help steam discharge remarkably. The veneer dried using ICD-fsb method had smooth and level surface, less deformation and warping, even moisture content, and high utilization rate. The time for opening hot board to discharge steam,which, early or late, is a key to obtain good drying result, was determined at the time when the core's temperature of veneer reaches 100℃ (vaporization). Using ICD-fsb method, the shrinking rates in tangent of veneer were from 1.90% to 2.26% for veneer of 0.4 mm in thickness,2.49% to 4.50% for veneer of 1 mm in thickness and 1.34% to 3.30% for veneer of 1.7 mm in thickness, which are much lower than the results obtained by other drying methods. The method of ICD-fsb offers a reliable technological guarantee for solving the deformation problem of veneer drying, especially the deformation of wood from quick-growing plantation.
基金The research was supported by the National Hi-Tech R ＆ D Program （863） of China （2002AA24515）. Natural Science Foundation of Heilonjiang Province （C0210） and Harbin City Youth Science Fund （2004AFQXJ027）.
文摘In an effort to find suitable wood from natural forest to meet the demand for veneer products, the yield and tensile strength of veneers produced from Brachystegia nigerica were investigated. Two trees of B. nigerica were separately selected from 10 different natural forest zones while two logs were obtained from each tree. The logs were debarked and steamed in a vat prior to rotary peeling and slicing for veneer production. The optimum steam temperature was determined by considering different temperatures: 50°C, 60°C, 70°C, 80°C and 90°C for 24 h. Thereafter, optimum steam time was determined at the optimum temperature by considering durations of 24, 48, 72 and 96 h. The average taper of 0.75 mm per 1.0 m length was recorded for B. nigerica, indicating that the logs were reasonably cylindrical; thereby its logs are good for the production of veneer. The yield ranged from 44% to 61% with an average of 52% of the log input. The tensile strength of the veneer was tested perpendicular to grain and both peeled and sliced veneers had the highest tensile strength between 70°C and 90°C, suggesting that softening of wood polymers, especially lignin, is between 70°C and 90°C. The optimum temperature and time for veneer production are 70°C and 48 h, respectively. Commercial production of veneer from B. nigerica is feasible based on the yield and mechanical properties of the obtained veneer, thereby encouraging the expansion of the scope ofits utilization.
文摘Objective :To evaluale the color change of the two-layer porcelain laminate veneer after adding veneering porcelain of differeat thickness to the 0.2mm thick aluminum oxide.Methods:Ten alumium axide disks were randomized into 2 groups.Each of five disks was veneered with Vita Lumin Shade B4 porcelain of thickness of 0.4mm and 0.6mm respectively.The L*a*b* color notations of the substrate covered with non-veneered disks and 2 thickness porcelain veneered disks were measured separtely and the color differences(ΔE) were calculated.Results:Statistically significant differences in color coordinates of dark substrates were recorded after the sustrate was covered by an aluminum oxide disk and also after the addition of veneering porcelain to the alumimum axide disks in group 1(P=0.0002) and group 2(P=0.0075) and between 2 groups(P=0.0001).Conclusion:The ability of masking underlying discoloration was increased and shifted to gray when the thickness of veneering porcelain increased.
基金Sponsored by the Science Fund of Harbin City(Grant No.2005AA6CN080) and Science Found of Heilongjiang Province(Grant No.GB06B303 -3).
文摘The discoloration of Scot pine （Pinus sylvestris var. Mongolica） veneers caused by resin-eliminated treatment and the reversion of the color were studied. The result showed that the color of the veneers changed from buff to yellowish brown after the treatment of resin elimination and the discoloration of heartwood was more severe than that of sapwood; the degree of discoloration was significantly positively correlated with the medicament strength, temperature and resin-eliminated duration. The variance analysis showed the effects of those three factors on the discoloration were significant. With hydrogen peroxide （H2O2） as color reversion medicament and inorganic compound as medium of the reaction, the reversion of the color of heartwood was more inaccessible than that of sapwood; the degree of the color’s reversion was positively correlated with the H2O2 strength, temperature and treating time; the H2O2 concentration has significant effects on the discoloration. In order to reduce discoloration of Scot pine veneers, medicament of resin-eliminated used have to be at some low concentration, and the optimal concentration of H2O2 is 0.35% during the process of color’s reversion.
文摘The stress-strain relation of laminated veneer lumber (LVL) was established by the method of regression, and its constitutive equation at large deformation and constant loading conditions was given to predict the static mechanical behaviors of LVL.
