This study carried out the underwater and in-air wire-feed laser deposition of an aluminium alloy with a thin-walled tubular structure. For both the underwater and in-air deposition layers, both were well-formed and i...This study carried out the underwater and in-air wire-feed laser deposition of an aluminium alloy with a thin-walled tubular structure. For both the underwater and in-air deposition layers, both were well-formed and incomplete fusion, cracks, or other defects did not exist.Compared with the single-track deposition layer in air, the oxidation degree of the underwater single-track deposition layer was slightly higher.In both the underwater and in-air deposition layers, columnar dendrites nucleated close to the fusion line and grew along the direction of the maximum cooling rate in the fusion region(FR), while equiaxed grains formed in the deposited region(DR). As the environment changed from air to water, the width of DR and height of FR decreased, but the deposition angle and height of DR increased. The grain size and ratio of the high-angle boundaries also decreased due to the large cooling rate and low peak temperature in the water environment.Besides, the existence of a water environment benefitted the reduction of magnesium element burning loss in the DR. The microhardness values of the underwater deposition layer were much larger than those of the in-air layer, owing to the fine grains and high magnesium content.展开更多
Direct synthesis of liquefied petroleum gas （LPG） from syngas was carried out over hybrid catalyst consisting of methanol synthesis catalyst and modified Y zeolite with Pd and Ca by different methods. The decrease o...Direct synthesis of liquefied petroleum gas （LPG） from syngas was carried out over hybrid catalyst consisting of methanol synthesis catalyst and modified Y zeolite with Pd and Ca by different methods. The decrease of CO conversion was mostly attributable to the sintering of Cu in methanol synthesis catalyst. On the other hand, coke deposition on Y zeolite was the reason for the decrease of LPG selectivity. The introduction of Ca decreased the strong acid sites of Y zeolite, suppressed coke formation, and thus improved the stability of hybrid catalyst.展开更多
Spur dykes are the structures which are used to protect the eroding bank of rivers.They are sometimes also used to safeguard the life of many structures such as bridge piers,abutments etc.The efficiency of spur ...Spur dykes are the structures which are used to protect the eroding bank of rivers.They are sometimes also used to safeguard the life of many structures such as bridge piers,abutments etc.The efficiency of spur dykes has been checked in straight channels by conducting model tests in laboratories by many investigators.Very few studies were done in curved channels.In present work an attempt has been made to study the effect of location of spur dyke on bed and scour around bridge pier in curved open channel(bend angle=80o)with time.Experiment has been carried out in 80o channel bend at constant discharge(3.5×10^(-3) m^(3)/s)and bridge pier is located at angular displacementϴ=60o.Hereϴis the angle the line drawn at the inlet of any bend to the line joining the centre of curvature and any point on the outer portion of the bend.It is found that maximum scouring occurs atϴ=0o and 20oalong inner wall and atϴ=60o and 80o along outer wall.It is also found that scouring around bridge pier is more in the vicinity of pier and decreases with increase in distance from pier.The most suitable location for spur dyke to protect bridge pier is at angular displacementϴ=20o.Scour developed rapidly during initial time and then rate of scouring decreases with elapse of time.展开更多
have been done in the past by many researchers.Many factors which affect scour around piers such as shape of piers,size,positioning and orientation etc.have been studied in detail by them.However,similar studies in me...have been done in the past by many researchers.Many factors which affect scour around piers such as shape of piers,size,positioning and orientation etc.have been studied in detail by them.However,similar studies in meandering channels are scanty.Very few researchers have studied the effect of angular displacement which has considerable effects of scour around bridge piers.In this paper an attempt has been made to carry out a detailed study of angular displacement on scour.A constant diameter bridge pier of circular shape has been tested in a meandering channel bend with bend angle as 800.The test bed was prepared by using uniform sand having d50 as 0.27 mm and run was taken for a discharge of 2.5 l/s.展开更多
Detailed studies on geophysical data and metallogeny of the Qinling region reveal the relationship between the deep crust-mantle structure and the distribution of mineral deposits. In the East Qinling, the Mesoznic mi...Detailed studies on geophysical data and metallogeny of the Qinling region reveal the relationship between the deep crust-mantle structure and the distribution of mineral deposits. In the East Qinling, the Mesoznic mineralization intensity is mainly controlled by the Lushan deep fault zone. The differences of mineral deposit types between the East and West Qinling are related to the distinction of rheological adjusting actions of the crust-mantle. The three-dimensional structure of grade separation bridge pattern controls the distribution of mineral deposits, especially to the distribution of Mesozoic large deposits.展开更多
The objective of this study was to determine the role of functional groups of silane coupling on bioactive titanium （Ti） surface by electrochemical deposition, and calcium phosphate （CAP） coating, as well as bone ...The objective of this study was to determine the role of functional groups of silane coupling on bioactive titanium （Ti） surface by electrochemical deposition, and calcium phosphate （CAP） coating, as well as bone cell adhesion and proliferation. Methyl group （-CH3）, amino group （-NH2）, and epoxy group （-glyph name--C（O）C） were introduced onto the bioactive Ti surface using self-assembled monolayers （SAMs） with different silane coupling agents as molecular bridges. The effect of the surface functional groups on the growth features of the CaP crystals was analyzed （including chemical compositions, element content, minerals morphology and crystal structure etc.）. CH3-terminated SAMs showed a hydrophobic surface and others were hydrophilic by contact angle measurement; NH2-terminated SAMs showed a positive charge and others were negatively charged using zeta-potential measurement. Scanning electron microscopy results confirmed that flower-like structure coatings consisting of various pinpoint-like crystals were formatted by different functional groups of silane coupling, and the CaP coatings were multicrystalline consisting of hydroxyapatite （HA） and precursors. CaP coating of CH3-terminated SAMs exhibited more excellent crystallization property as compared to coatings of --NH2 and -C（O）C groups. In vitro MC3T3- El cells adhesion and proliferation were performed. The results showed that CaP coatings on silane coupling functionalized surfaces supported cell adhesion and proliferation. Thus, these functional groups of silane coupling on Ti can form homogeneous and oriented nano-CaP coatings and provide a more biocompatible surface for bone regeneration and biomedical applications.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities (No. HIT.OCEF.2021036)。
文摘This study carried out the underwater and in-air wire-feed laser deposition of an aluminium alloy with a thin-walled tubular structure. For both the underwater and in-air deposition layers, both were well-formed and incomplete fusion, cracks, or other defects did not exist.Compared with the single-track deposition layer in air, the oxidation degree of the underwater single-track deposition layer was slightly higher.In both the underwater and in-air deposition layers, columnar dendrites nucleated close to the fusion line and grew along the direction of the maximum cooling rate in the fusion region(FR), while equiaxed grains formed in the deposited region(DR). As the environment changed from air to water, the width of DR and height of FR decreased, but the deposition angle and height of DR increased. The grain size and ratio of the high-angle boundaries also decreased due to the large cooling rate and low peak temperature in the water environment.Besides, the existence of a water environment benefitted the reduction of magnesium element burning loss in the DR. The microhardness values of the underwater deposition layer were much larger than those of the in-air layer, owing to the fine grains and high magnesium content.
基金supported by the National Key Technology R & D Program of China(No.2011BAD22B06)BP Company through the Clean Energy Facing the Future Program at Dalian Institute of Chemical Physics
文摘Direct synthesis of liquefied petroleum gas （LPG） from syngas was carried out over hybrid catalyst consisting of methanol synthesis catalyst and modified Y zeolite with Pd and Ca by different methods. The decrease of CO conversion was mostly attributable to the sintering of Cu in methanol synthesis catalyst. On the other hand, coke deposition on Y zeolite was the reason for the decrease of LPG selectivity. The introduction of Ca decreased the strong acid sites of Y zeolite, suppressed coke formation, and thus improved the stability of hybrid catalyst.
文摘Spur dykes are the structures which are used to protect the eroding bank of rivers.They are sometimes also used to safeguard the life of many structures such as bridge piers,abutments etc.The efficiency of spur dykes has been checked in straight channels by conducting model tests in laboratories by many investigators.Very few studies were done in curved channels.In present work an attempt has been made to study the effect of location of spur dyke on bed and scour around bridge pier in curved open channel(bend angle=80o)with time.Experiment has been carried out in 80o channel bend at constant discharge(3.5×10^(-3) m^(3)/s)and bridge pier is located at angular displacementϴ=60o.Hereϴis the angle the line drawn at the inlet of any bend to the line joining the centre of curvature and any point on the outer portion of the bend.It is found that maximum scouring occurs atϴ=0o and 20oalong inner wall and atϴ=60o and 80o along outer wall.It is also found that scouring around bridge pier is more in the vicinity of pier and decreases with increase in distance from pier.The most suitable location for spur dyke to protect bridge pier is at angular displacementϴ=20o.Scour developed rapidly during initial time and then rate of scouring decreases with elapse of time.
文摘have been done in the past by many researchers.Many factors which affect scour around piers such as shape of piers,size,positioning and orientation etc.have been studied in detail by them.However,similar studies in meandering channels are scanty.Very few researchers have studied the effect of angular displacement which has considerable effects of scour around bridge piers.In this paper an attempt has been made to carry out a detailed study of angular displacement on scour.A constant diameter bridge pier of circular shape has been tested in a meandering channel bend with bend angle as 800.The test bed was prepared by using uniform sand having d50 as 0.27 mm and run was taken for a discharge of 2.5 l/s.
文摘Detailed studies on geophysical data and metallogeny of the Qinling region reveal the relationship between the deep crust-mantle structure and the distribution of mineral deposits. In the East Qinling, the Mesoznic mineralization intensity is mainly controlled by the Lushan deep fault zone. The differences of mineral deposit types between the East and West Qinling are related to the distinction of rheological adjusting actions of the crust-mantle. The three-dimensional structure of grade separation bridge pattern controls the distribution of mineral deposits, especially to the distribution of Mesozoic large deposits.
基金supported by the National Key Basic Research Program of China (No. 2012CB619100)the National Natural Science Foundation of China (No. 51541201, 51372087)+2 种基金the Science and Technology Planning Project of Guangdong Province, China (No. 2014A010105048)the Natural Science Foundation of Guangdong Province, China (No. 2015A030313493)the State Key Laboratory for Mechanical Behavior of Materials, China (No. 20141607)
文摘The objective of this study was to determine the role of functional groups of silane coupling on bioactive titanium （Ti） surface by electrochemical deposition, and calcium phosphate （CAP） coating, as well as bone cell adhesion and proliferation. Methyl group （-CH3）, amino group （-NH2）, and epoxy group （-glyph name--C（O）C） were introduced onto the bioactive Ti surface using self-assembled monolayers （SAMs） with different silane coupling agents as molecular bridges. The effect of the surface functional groups on the growth features of the CaP crystals was analyzed （including chemical compositions, element content, minerals morphology and crystal structure etc.）. CH3-terminated SAMs showed a hydrophobic surface and others were hydrophilic by contact angle measurement; NH2-terminated SAMs showed a positive charge and others were negatively charged using zeta-potential measurement. Scanning electron microscopy results confirmed that flower-like structure coatings consisting of various pinpoint-like crystals were formatted by different functional groups of silane coupling, and the CaP coatings were multicrystalline consisting of hydroxyapatite （HA） and precursors. CaP coating of CH3-terminated SAMs exhibited more excellent crystallization property as compared to coatings of --NH2 and -C（O）C groups. In vitro MC3T3- El cells adhesion and proliferation were performed. The results showed that CaP coatings on silane coupling functionalized surfaces supported cell adhesion and proliferation. Thus, these functional groups of silane coupling on Ti can form homogeneous and oriented nano-CaP coatings and provide a more biocompatible surface for bone regeneration and biomedical applications.
