In order to study the relationship between biological and pharmacological activities with their structures, a series of tri- and tetra-oxygenated xanthones including 1-hydroxyl-2,3,4,7- tetramethoxy xanthone 1, 1-hydr...In order to study the relationship between biological and pharmacological activities with their structures, a series of tri- and tetra-oxygenated xanthones including 1-hydroxyl-2,3,4,7- tetramethoxy xanthone 1, 1-hydroxyl-2,3,4,5-tetramethoxyl xanthone 2, 1-hydroxyl-3,5-dimethoxy- xanthone 3, 1,8-dihydroxyl-3,5-dimethoxyl xanthone 4 and 1,5,8-trihydroxyl-3-methoxy xanthone 5 have been isolated from Swertia chirayita. Their structures were established on the basis of spectral and chemical evidences. The crystal structure of 5 was also investigated by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic system, space group P?with a = 7.1540(10), b = 7.520(2), c = 10.671(2) , V = 562.7(2) 3 , α = 86.50(3), β = 80.06(3) , γ = 85.00(3), Z = 2, Dc = 1.618 g/m3, R = 0.0405, wR = 0.1028 and F(000) = 284. The molecular structure of 5 is nearly planar and four substituents are much closer to the plane. Compound 5 contains three intermolecular hydro- gen bonds. A recent study shows that phenolic hydroxyls in xanthones are the main active groups capable of scavenging OH and O2.展开更多
The electrocatalytic synthesis of propylene carbonate（PC） from CO2 and propylene oxide（PO） was studied under mild conditions（PCO2=1.01×105 Pa, t=25 ℃）. Influences of solvents, supporting electrolytes, the ...The electrocatalytic synthesis of propylene carbonate（PC） from CO2 and propylene oxide（PO） was studied under mild conditions（PCO2=1.01×105 Pa, t=25 ℃）. Influences of solvents, supporting electrolytes, the passed charge, the nature of electrodes and the current density（j） on the yield of PC were investigated to optimize the electrolytic conditions, with the maximal yield to be 46.2%, the selectivity of propylene carbonate is 100%. The reduction of propylene oxide in the absence and presence of CO2 was examined by cyclic voltammetry. The mechanism of the reaction initiated by the synergistic effect of halides ions of supporting electrolytes with nucleophilicity and the metal ions from scarification anode with Lewis acid acidity was proposed on the basis of our results.展开更多
The influence of coarse Cu-bearing particles, matrix and subgrain boundary precipitates on the stress corrosion susceptibility of the Al-Zn-Mg-Cu alloys was investigated. The strength of 7150 alloy is about 15 MPa hig...The influence of coarse Cu-bearing particles, matrix and subgrain boundary precipitates on the stress corrosion susceptibility of the Al-Zn-Mg-Cu alloys was investigated. The strength of 7150 alloy is about 15 MPa higher than that of 7010 alloy. The 7010 alloy exhibits higher resistance to stress corrosion cracking as compared with the 7150 alloy. The coarse Cu-bearing particles are detrimental to the resistance to stress corrosion cracking. The increase of size of matrix and subgrain boundary precipitates decreases the susceptibility of stress corrosion. The anodic dissolution and hydrogen embrittlement govern the cracking process. The severity of stress corrosion cracking is shown to be related to the coarse Cu-bearing particles, matrix and subgrain precipitates in Al-Zn-Mg-Cu alloys.展开更多
Fluorescence material of Sm doped Si-Ca-Mg system was synthesized by using the method of solid phase reaction at high temperature. The phase composition and crystal structure of this material were analyzed with XRD me...Fluorescence material of Sm doped Si-Ca-Mg system was synthesized by using the method of solid phase reaction at high temperature. The phase composition and crystal structure of this material were analyzed with XRD method for its composition and the existence form of Sm atom. We aimed to exactly determine the phase composition of this fluorescence material and the doping position and environment of rare-earth Sm atom in the system because these factors have significant effects on the properties. The analytical results show that the Sm atoms dope in Ca2O26Si6Sm8 lattice in the form of atomic site-occupation in three different space positions with different occupancy rates. Therefore, based on the XRD analytical results, the fluorescence material of Sm doped Si-Ca-Mg system with high performance can be synthesized.展开更多
The technology of Intelligent cure operation is set forth according to developing tendency of smart material and structure. Intelligent-system-based tool was developed in order to operate the autoclave cure of a fiber...The technology of Intelligent cure operation is set forth according to developing tendency of smart material and structure. Intelligent-system-based tool was developed in order to operate the autoclave cure of a fiber reinforced thermosetting matrix composite laminate in an optimal manner. The objective function is comforts for minimizing the total cure time, uniforming the temperature distribution, controling exothermal and minimizing the process-induced residual stresses in the laminate. Data is analyzed on-line to determine the trends in real-time. The results from application of this overall strategy for the curing of composites are presented.展开更多
The occurrence and fate of hydroxylated polybrominated diphenyl ethers（OH-PBDEs） and methoxylated polybrominated diphenyl ethers（Me O-PBDEs） have received significant attention. However, there is limited informati...The occurrence and fate of hydroxylated polybrominated diphenyl ethers（OH-PBDEs） and methoxylated polybrominated diphenyl ethers（Me O-PBDEs） have received significant attention. However, there is limited information on the metabolism relationship between OH-pentaB DEs and MeO-pentaB DEs that were frequently detected with relatively high concentrations in the environment. In this study, the biotransformation between OH-BDE-99 and MeO-BDE-99 was investigated in rice, wheat, and soybean plants. All the three plants can metabolize OH-BDE-99 to corresponding homologous methoxylated metabolites, while the transformation from MeO-BDE-99 to OH-BDE-99 could only be found in soybean. The conversion of parent compounds was the highest in soybean, followed by wheat and rice. Transformation products were found mainly in the roots, with few metabolites being translocated to the shoots and solution after exposure. The results of this study provide valuable information for a better understanding of the accumulation and transformation of OH-PBDEs and MeO-PBDEs in different plants.展开更多
Titanium slag in this study was produced by subjecting titanomagnetite concentrate to direct reductionelectric furnace smelting. Processing mineralogy and mineral phase reconstruction behavior at high temperature and ...Titanium slag in this study was produced by subjecting titanomagnetite concentrate to direct reductionelectric furnace smelting. Processing mineralogy and mineral phase reconstruction behavior at high temperature and slow cooling treatment were examined by chemical analysis, X-ray diffraction （XRD）, optical microscopy （OM）, scanning electron microscopy （SEM）, and energydispersive spectroscopy （EDS）. Anosovite solid solution is the main titanium product by the direct reduction and smelting process. Results of slow-cooling experiments show that crystal volume and size increase as cooling rate decreases. Anosovite and gangue mineral crystals develop fully with large crystal volume and size at a cooling rate of 2 K.min-1. Moreover, the growth of anosovite crystal was characterized by crystal nucleation and growth theory. These results provide further insights into the separation of anosovite from gangue by mineral processing.展开更多
A new tripodal ligand, N, N, N′, N′, N″, N″ hexaisopropyl 2, 2′, 2″ nitrilotris (2,1 ethoxy) triacetamide (L) and its new erbium picrate complex were prepared. The structure of the complex was determined by...A new tripodal ligand, N, N, N′, N′, N″, N″ hexaisopropyl 2, 2′, 2″ nitrilotris (2,1 ethoxy) triacetamide (L) and its new erbium picrate complex were prepared. The structure of the complex was determined by X ray crystal structure analysis. The result reveals that the Er 3+ is encapsulated by the three arms of the tripodal ligand, and nine coordinated by the bridged head nitrogen atom, all ether oxygen atoms and carbonyl oxygen atoms of the ligand, and two oxygen atoms of the bidentate picrate. The coordination polyhedron is a distorted mono-capped square antiprism.展开更多
The effect of quench rate and transfer time on the precipitation sequence and mechanical properties of an Al-Zn-Mg-Cu-Zr alloy was investigated. A consistent trend of the decrease of ductility with the decrease of que...The effect of quench rate and transfer time on the precipitation sequence and mechanical properties of an Al-Zn-Mg-Cu-Zr alloy was investigated. A consistent trend of the decrease of ductility with the decrease of quench rate and the increase of transfer time was observed. This is attributed to the quench-induced precipitates of equilibrium MgZn2 phase formed along subgrain and grain boundaries, which promotes the intergranular fracture. The strength decreases greatly when the transfer time is over 90s, resulting from the heterogeneous precipitation on dispersoids or dislocations. The quench water temperature has a little influence on the evolution of matrix precipitates and strength. This alloy exhibits less quench sensitivity.展开更多
An attempt to grow single crystalline thin films of body-centered-cubic(bcc)Mn on InP(001)has been carried out by molecular beam epitaxy.In situ reflection high energy electron diffraction and ex situ x-ray diffractio...An attempt to grow single crystalline thin films of body-centered-cubic(bcc)Mn on InP(001)has been carried out by molecular beam epitaxy.In situ reflection high energy electron diffraction and ex situ x-ray diffraction are used to characterize the film and interface structures.It is found that the metastable phase of bcc Mn fails to stabilize on the substrate despite of their perfect lattice-match.This result suggests again the importance of interface structure in the epitaxy of 3d metals on semiconductors.展开更多
The evolution of the eutectic structures in the alloys with different copper contents during heat treatment was studied by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS), and differential...The evolution of the eutectic structures in the alloys with different copper contents during heat treatment was studied by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS), and differential scanning calorimetry(DSC). The as cast microstructures involve α(Al), eutectic(α(Al) + Mg(Al, Cu, Zn)2) and Al7Cu2Fe. The Al2CuMg particles form during heat treatment. The volume of coarse phases decreases quickly in the initial 12 h during heat treatment. The volume of coarse phases change a little at 400 and 420 ℃. Copper content has a great influence on the evolution of the eutectic. The coarse phases dissolve slowly in alloy with higher copper content.展开更多
Supercooling of the microencapsulated phase change materials（PCMs） during cooling usually happens. This phenomenon can interfere with heat transfer and is necessary to further overcome. In this study, mela- mine-for...Supercooling of the microencapsulated phase change materials（PCMs） during cooling usually happens. This phenomenon can interfere with heat transfer and is necessary to further overcome. In this study, mela- mine-formaldehyde microcapsules containing two n-alkane PCMs, namely, n-dodecane（Cl2） or n-tetradecane（C14） were prepared by in situ polymerization. A small amount of n-hexatriacontane（C36） was introduced as an organic ge- lator into the core of microcapsules to cope with the supercooling problem. Analyses demonstrate that supercooling of the microencapsulated C12 or C14 was significantly suppressed by adding 3%（mass fraction） C36, without changing the spherical morphology and dispersibility. It could be also found that the enthalpy of microencapsulated CI2 or C14 containing C36 was similar to that of microencapsulated n-alkanes without C36, whereas the difference between onsets of crystallization and melting（degree of supercooling） is similar to that of those of pure n-alkanes, suggesting the re- markable suppression ability of the organic gelator on supercooling.展开更多
Vacuum ultraviolet radiation of Upilex-S polyimide film 25μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on th...Vacuum ultraviolet radiation of Upilex-S polyimide film 25μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on the films were observed and the nanoparticles formed on the surface consist mainly of carbon clusters.Changes in the composition and the chemical characteristics of film surface after radiation were identified by X-ray photoelectron spectroscopy(XPS).Relative O content in the radiated area was found to be higher,while N content was lower than in the pristine area.This indicates that Upilex-S polyimide film releases N atoms as volatile species.And the C1s,O1s envelopes were fitted using Multipak Spectrum software.The surface morphologies on iradiated area were examined by Atomic Force Microscope(AFM).Pieces of radiant products protrude from the eradiated surface,leading to considerable roughness for the iradiated area.And the surface transmittance of Upilex-S film after radiation reduces.展开更多
Electrocarboxylation of anthrone in the presence of CO2 to anthrance-9-carboxylic acid directly was carried out. The electroreduction behavior of anthrone was examined by cyclic voltammetry in the absence and presence...Electrocarboxylation of anthrone in the presence of CO2 to anthrance-9-carboxylic acid directly was carried out. The electroreduction behavior of anthrone was examined by cyclic voltammetry in the absence and presence of CO2. Then the influences of the supporting electrolytes, temperature, electrode material and anthrone concentration on the carboxylation yield were investigated. Under the optimized conditions, anthrancene-9-carboxylic acid was obtained in a good yield（96.1%）.展开更多
This paper focused on the folding damage behavior of the space rigidizable materials in terms of 3-1ayer composite membranes. An experimental scheme was presented. The composite membranes were folded between the two p...This paper focused on the folding damage behavior of the space rigidizable materials in terms of 3-1ayer composite membranes. An experimental scheme was presented. The composite membranes were folded between the two plates for a short time, and then the unfolded composite membranes were compressively cured in an oven. By adjusting the displacement of one plate, the folding radius was changed. As expected, the strength and effective modulus of the cured composite membranes drop with decreasing the folding radius. When the strain controlled failure rule is appliedto the composite membranes, a minimal folding radius can be reached, beyond which the membranes will keep intact.Furthermore, folding damage due to folding and unfolding processes was evaluated by a simplified model. Compared with the measured residual strength and effective modulus, calculated results have the same trend. A discrepancy is attributed to neglecting the effects of the transverse fibers and the matrix.展开更多
Infiltration-in situ reaction synthesis of Cf/TiAl3 composite was investigated. The as-cast material was obtained by titanium particles, carbon fibers and pure aluminum. Titanium particles and carbon fibers were mixed...Infiltration-in situ reaction synthesis of Cf/TiAl3 composite was investigated. The as-cast material was obtained by titanium particles, carbon fibers and pure aluminum. Titanium particles and carbon fibers were mixed and pressed to form a preform firstly, and then molten pure aluminum was pressed into the preform, subsequently, cooled rapidly. In situ reaction samples were obtained by heating the as-cast material from 600 to 1000℃ for I h. The microstructural evolution of in situ reaction samples was analyzed by scanning electron microscopy and energy dispersive X-ray. In addition, the phase composition of products was inspected by X-ray diffraction. Experimental results showed that the dominant product of TiAl3 and a small amount of Al4C3 were formed at low temperature. While TiAl3 was not stable at high temperature, along with its decrease, TiC phase became favorable. In the final products, TiAl3, TiC and Al4C3 were detected. Thus, the in situ reaction for Ti-Al-C system composite proceeded a formed-decomposed-precipitated mechanism.展开更多
Al-Zn-Mg-Cu alloy is a favorable choice for aerospace applications requiring good combination of strength and toughness, which is greatly influenced by the coarse intermetallic particles. The evolution of intermetalli...Al-Zn-Mg-Cu alloy is a favorable choice for aerospace applications requiring good combination of strength and toughness, which is greatly influenced by the coarse intermetallic particles. The evolution of intermetallic particles in an Al-Zn-Mg-Cu alloy during heat treatment was studied by field emission gun scanning electron microscopy (FEG-SEM) and X-ray diffractometry(XRD). The results show that there are lamellar eutectic structure (α(Al)+Mg(Zn,Al,Cu)2) and Al7Cu2Fe particles in the solidified structure. The Al7Cu2Fe particles are embedded in the eutectic structure. The content of eutectic structure decreases with the increase of holding time and disappears after 24 h. The size and morphology of Al7Cu2Fe particles exhibit no change during the heat treatment. It is found that the Al2CuMg phase is formed during the treatment at 460℃. A transformation process from the primary eutectic phase Mg(Zn,Al,Cu)2 to Al2CuMg is observed, and the transformation mechanism and kinetics are analyzed. The Al2CuMg constituents form in the primary Mg(Zn,Al,Cu)2 phase, and grow along the eutectic microstructure.展开更多
Crystalline AusSi2/Si heterojunetion nanowires （AusSi2/SiNWs） are obtained by thermal evaporating SiO pow- ders on thick gold-coated silicon substrates in a low vacuum system. Structure analysis of the produced AusS...Crystalline AusSi2/Si heterojunetion nanowires （AusSi2/SiNWs） are obtained by thermal evaporating SiO pow- ders on thick gold-coated silicon substrates in a low vacuum system. Structure analysis of the produced AusSh/Si heterojunetions is performed by employing a transmission electron microscope （TEM） and a selected area electric diffraetometer. The chemical compositions axe studied by a energy-dispersive x-ray spectroscope attached to the TEM. A two-step growth model is proposed to describe the formation of the AusSi2/SiNWs. During the first step, crystalline SiNWs are formed via a growth mechanism combining the oxide-assisted growth process with the vapour-liquid-solid model at relatively high temperature. In the second step, the temperature decreases and one segment of the preformed SiNWs reacts with the remnant Au to form single crystalline AusSi2 nanowires by a solid-liquid-solid process. The present work should be useful for the future synthesis and research of high-quality gold silicide nanowires and microelectronic devices based on the nanowires.展开更多
Tackling fogging and microbial infection problems related to the endoscope lens remain challenges due to visual disturbances and bacterial threats to human health.Herein,highly transparent antifogging and antibacteria...Tackling fogging and microbial infection problems related to the endoscope lens remain challenges due to visual disturbances and bacterial threats to human health.Herein,highly transparent antifogging and antibacterial coatings were developed in a facile way by thermal curing of zwitterionic copolymers poly(n-butyl methacrylate-co-2-aminoethyl methacrylate-co-sulfobetaine methacrylate)s with 1,3,5-triformylbenzene.Characterizations of surface chemical composition and wettability suggested that the copolymer coatings exhibited amphiphilicity with a hydrophobic surface and internal hydrophilicity.The prepared amphiphilic coating exhibited excellent antifogging properties both in vivo and in vitro.The introduction of hydrophobic n-butyl methacrylate and cationic aminoethylmethacrylate could improve the stability and antibacterial capability of the coating.The growth inhibition rates of the coatings against Staphylococcus aureus and Escherichia coli were up to 99%and the copolymer coatings with the zwitterionic groups had low hemolytic rates less than 3%.The amphiphilic copolymer coatings combined antifogging and antibacterial properties may have a promising potential for applications in biomedical devices.展开更多
The La(III) complex with a new amide-type tripodal ligand, 2,2,2-nitrilotris{[(2-benzylaminoformyl)- phenoxy]ethyl}amine (L), was synthesized and characterized by X-ray crystallographic analysis. Crystal data: C48H55....The La(III) complex with a new amide-type tripodal ligand, 2,2,2-nitrilotris{[(2-benzylaminoformyl)- phenoxy]ethyl}amine (L), was synthesized and characterized by X-ray crystallographic analysis. Crystal data: C48H55.50LaN7O18.75, Mr=1169.40, monoclinic, space group, P21/n, a=1.0644(3) nm, b=2.3889(5) nm, c=2.1917(5) nm, b=90.65, V=5.573(2) nm3, Z=1, Dc=1.394 gcm-3, R1=0.0487, wR [I>2s(I)]=0.1266. The results reveal that each La(III) ion binds to 9 oxygen atoms, three of which belong to carbonyl groups from three tripodal ligands and six to three bidentate nitrate groups and a two-dimensional sheet of 4.82 networks is assembled by metal-ligand coordination interaction. L, a heptadentate compound, merely acts as a tridentate bridging spacer due to its steric hindrance and links the La(III) ions as three-connected nodes.展开更多
基金The project was supported by the Key Laboratory for Natural Medicine of Gansu Province and Foundation of Lanzhou University of Technology
文摘In order to study the relationship between biological and pharmacological activities with their structures, a series of tri- and tetra-oxygenated xanthones including 1-hydroxyl-2,3,4,7- tetramethoxy xanthone 1, 1-hydroxyl-2,3,4,5-tetramethoxyl xanthone 2, 1-hydroxyl-3,5-dimethoxy- xanthone 3, 1,8-dihydroxyl-3,5-dimethoxyl xanthone 4 and 1,5,8-trihydroxyl-3-methoxy xanthone 5 have been isolated from Swertia chirayita. Their structures were established on the basis of spectral and chemical evidences. The crystal structure of 5 was also investigated by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic system, space group P?with a = 7.1540(10), b = 7.520(2), c = 10.671(2) , V = 562.7(2) 3 , α = 86.50(3), β = 80.06(3) , γ = 85.00(3), Z = 2, Dc = 1.618 g/m3, R = 0.0405, wR = 0.1028 and F(000) = 284. The molecular structure of 5 is nearly planar and four substituents are much closer to the plane. Compound 5 contains three intermolecular hydro- gen bonds. A recent study shows that phenolic hydroxyls in xanthones are the main active groups capable of scavenging OH and O2.
基金Supported by the National Natural Science Foundation of China(No.20973065)the Fund of Basic Research in Natural Science Issued by Shanghai Municipal Committee of Science+4 种基金 China(No.08dj1400100)the Shanghai Leading Project China (No.B409)the Foundation of Outstanding Young Talent in University of Anhui Province China No.2010SQRL042)
文摘The electrocatalytic synthesis of propylene carbonate（PC） from CO2 and propylene oxide（PO） was studied under mild conditions（PCO2=1.01×105 Pa, t=25 ℃）. Influences of solvents, supporting electrolytes, the passed charge, the nature of electrodes and the current density（j） on the yield of PC were investigated to optimize the electrolytic conditions, with the maximal yield to be 46.2%, the selectivity of propylene carbonate is 100%. The reduction of propylene oxide in the absence and presence of CO2 was examined by cyclic voltammetry. The mechanism of the reaction initiated by the synergistic effect of halides ions of supporting electrolytes with nucleophilicity and the metal ions from scarification anode with Lewis acid acidity was proposed on the basis of our results.
基金Project(2004AA5BG018) supported by the Science and Technology Development Fund of Harbin, China
文摘The influence of coarse Cu-bearing particles, matrix and subgrain boundary precipitates on the stress corrosion susceptibility of the Al-Zn-Mg-Cu alloys was investigated. The strength of 7150 alloy is about 15 MPa higher than that of 7010 alloy. The 7010 alloy exhibits higher resistance to stress corrosion cracking as compared with the 7150 alloy. The coarse Cu-bearing particles are detrimental to the resistance to stress corrosion cracking. The increase of size of matrix and subgrain boundary precipitates decreases the susceptibility of stress corrosion. The anodic dissolution and hydrogen embrittlement govern the cracking process. The severity of stress corrosion cracking is shown to be related to the coarse Cu-bearing particles, matrix and subgrain precipitates in Al-Zn-Mg-Cu alloys.
基金National Natural Science Foundation of China 20671020
文摘Fluorescence material of Sm doped Si-Ca-Mg system was synthesized by using the method of solid phase reaction at high temperature. The phase composition and crystal structure of this material were analyzed with XRD method for its composition and the existence form of Sm atom. We aimed to exactly determine the phase composition of this fluorescence material and the doping position and environment of rare-earth Sm atom in the system because these factors have significant effects on the properties. The analytical results show that the Sm atoms dope in Ca2O26Si6Sm8 lattice in the form of atomic site-occupation in three different space positions with different occupancy rates. Therefore, based on the XRD analytical results, the fluorescence material of Sm doped Si-Ca-Mg system with high performance can be synthesized.
文摘The technology of Intelligent cure operation is set forth according to developing tendency of smart material and structure. Intelligent-system-based tool was developed in order to operate the autoclave cure of a fiber reinforced thermosetting matrix composite laminate in an optimal manner. The objective function is comforts for minimizing the total cure time, uniforming the temperature distribution, controling exothermal and minimizing the process-induced residual stresses in the laminate. Data is analyzed on-line to determine the trends in real-time. The results from application of this overall strategy for the curing of composites are presented.
基金supported by the National Basic Research Program (973) of China (No. 2014CB441104)National Natural Science Foundation of China (Nos. 21520102009 and 21137003)the Zhejiang Provincial Natural Science Foundation of China (LY14B070009)
文摘The occurrence and fate of hydroxylated polybrominated diphenyl ethers（OH-PBDEs） and methoxylated polybrominated diphenyl ethers（Me O-PBDEs） have received significant attention. However, there is limited information on the metabolism relationship between OH-pentaB DEs and MeO-pentaB DEs that were frequently detected with relatively high concentrations in the environment. In this study, the biotransformation between OH-BDE-99 and MeO-BDE-99 was investigated in rice, wheat, and soybean plants. All the three plants can metabolize OH-BDE-99 to corresponding homologous methoxylated metabolites, while the transformation from MeO-BDE-99 to OH-BDE-99 could only be found in soybean. The conversion of parent compounds was the highest in soybean, followed by wheat and rice. Transformation products were found mainly in the roots, with few metabolites being translocated to the shoots and solution after exposure. The results of this study provide valuable information for a better understanding of the accumulation and transformation of OH-PBDEs and MeO-PBDEs in different plants.
基金financially supported by the Major Program of the National Natural Science Foundation of China(No.51090385)
文摘Titanium slag in this study was produced by subjecting titanomagnetite concentrate to direct reductionelectric furnace smelting. Processing mineralogy and mineral phase reconstruction behavior at high temperature and slow cooling treatment were examined by chemical analysis, X-ray diffraction （XRD）, optical microscopy （OM）, scanning electron microscopy （SEM）, and energydispersive spectroscopy （EDS）. Anosovite solid solution is the main titanium product by the direct reduction and smelting process. Results of slow-cooling experiments show that crystal volume and size increase as cooling rate decreases. Anosovite and gangue mineral crystals develop fully with large crystal volume and size at a cooling rate of 2 K.min-1. Moreover, the growth of anosovite crystal was characterized by crystal nucleation and growth theory. These results provide further insights into the separation of anosovite from gangue by mineral processing.
文摘A new tripodal ligand, N, N, N′, N′, N″, N″ hexaisopropyl 2, 2′, 2″ nitrilotris (2,1 ethoxy) triacetamide (L) and its new erbium picrate complex were prepared. The structure of the complex was determined by X ray crystal structure analysis. The result reveals that the Er 3+ is encapsulated by the three arms of the tripodal ligand, and nine coordinated by the bridged head nitrogen atom, all ether oxygen atoms and carbonyl oxygen atoms of the ligand, and two oxygen atoms of the bidentate picrate. The coordination polyhedron is a distorted mono-capped square antiprism.
文摘The effect of quench rate and transfer time on the precipitation sequence and mechanical properties of an Al-Zn-Mg-Cu-Zr alloy was investigated. A consistent trend of the decrease of ductility with the decrease of quench rate and the increase of transfer time was observed. This is attributed to the quench-induced precipitates of equilibrium MgZn2 phase formed along subgrain and grain boundaries, which promotes the intergranular fracture. The strength decreases greatly when the transfer time is over 90s, resulting from the heterogeneous precipitation on dispersoids or dislocations. The quench water temperature has a little influence on the evolution of matrix precipitates and strength. This alloy exhibits less quench sensitivity.
基金Supported by the National Natural Science Foundation of China under Grant Nos.19625410 and 19730004,Huo Ying-dong Foundation for Young Faculties in Chinese Universities,State Education Commission Foundation for Ph.D.Training,Shanghai Applied Physics CenterShanghai Venus Project for Young Scientist and Technicians.
文摘An attempt to grow single crystalline thin films of body-centered-cubic(bcc)Mn on InP(001)has been carried out by molecular beam epitaxy.In situ reflection high energy electron diffraction and ex situ x-ray diffraction are used to characterize the film and interface structures.It is found that the metastable phase of bcc Mn fails to stabilize on the substrate despite of their perfect lattice-match.This result suggests again the importance of interface structure in the epitaxy of 3d metals on semiconductors.
基金Project(2004AA5BG018) supported by the Science and Technology Development Fund of Harbin, China
文摘The evolution of the eutectic structures in the alloys with different copper contents during heat treatment was studied by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS), and differential scanning calorimetry(DSC). The as cast microstructures involve α(Al), eutectic(α(Al) + Mg(Al, Cu, Zn)2) and Al7Cu2Fe. The Al2CuMg particles form during heat treatment. The volume of coarse phases decreases quickly in the initial 12 h during heat treatment. The volume of coarse phases change a little at 400 and 420 ℃. Copper content has a great influence on the evolution of the eutectic. The coarse phases dissolve slowly in alloy with higher copper content.
文摘Supercooling of the microencapsulated phase change materials（PCMs） during cooling usually happens. This phenomenon can interfere with heat transfer and is necessary to further overcome. In this study, mela- mine-formaldehyde microcapsules containing two n-alkane PCMs, namely, n-dodecane（Cl2） or n-tetradecane（C14） were prepared by in situ polymerization. A small amount of n-hexatriacontane（C36） was introduced as an organic ge- lator into the core of microcapsules to cope with the supercooling problem. Analyses demonstrate that supercooling of the microencapsulated C12 or C14 was significantly suppressed by adding 3%（mass fraction） C36, without changing the spherical morphology and dispersibility. It could be also found that the enthalpy of microencapsulated CI2 or C14 containing C36 was similar to that of microencapsulated n-alkanes without C36, whereas the difference between onsets of crystallization and melting（degree of supercooling） is similar to that of those of pure n-alkanes, suggesting the re- markable suppression ability of the organic gelator on supercooling.
基金This work is financially supported by Development Program for Outstanding Young Teachers in Harbin Institute of Technology(No HIT200632)
文摘Vacuum ultraviolet radiation of Upilex-S polyimide film 25μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on the films were observed and the nanoparticles formed on the surface consist mainly of carbon clusters.Changes in the composition and the chemical characteristics of film surface after radiation were identified by X-ray photoelectron spectroscopy(XPS).Relative O content in the radiated area was found to be higher,while N content was lower than in the pristine area.This indicates that Upilex-S polyimide film releases N atoms as volatile species.And the C1s,O1s envelopes were fitted using Multipak Spectrum software.The surface morphologies on iradiated area were examined by Atomic Force Microscope(AFM).Pieces of radiant products protrude from the eradiated surface,leading to considerable roughness for the iradiated area.And the surface transmittance of Upilex-S film after radiation reduces.
基金Supported by the National Natural Science Foundation of China(No.20973065)the"Chen Guang"Project Supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation,China(No.10CG26)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20100076120020)the Foundation of Outstanding Yong Talent in University of Anhui Province,China(No.2010SQRL042)
文摘Electrocarboxylation of anthrone in the presence of CO2 to anthrance-9-carboxylic acid directly was carried out. The electroreduction behavior of anthrone was examined by cyclic voltammetry in the absence and presence of CO2. Then the influences of the supporting electrolytes, temperature, electrode material and anthrone concentration on the carboxylation yield were investigated. Under the optimized conditions, anthrancene-9-carboxylic acid was obtained in a good yield（96.1%）.
文摘This paper focused on the folding damage behavior of the space rigidizable materials in terms of 3-1ayer composite membranes. An experimental scheme was presented. The composite membranes were folded between the two plates for a short time, and then the unfolded composite membranes were compressively cured in an oven. By adjusting the displacement of one plate, the folding radius was changed. As expected, the strength and effective modulus of the cured composite membranes drop with decreasing the folding radius. When the strain controlled failure rule is appliedto the composite membranes, a minimal folding radius can be reached, beyond which the membranes will keep intact.Furthermore, folding damage due to folding and unfolding processes was evaluated by a simplified model. Compared with the measured residual strength and effective modulus, calculated results have the same trend. A discrepancy is attributed to neglecting the effects of the transverse fibers and the matrix.
文摘Infiltration-in situ reaction synthesis of Cf/TiAl3 composite was investigated. The as-cast material was obtained by titanium particles, carbon fibers and pure aluminum. Titanium particles and carbon fibers were mixed and pressed to form a preform firstly, and then molten pure aluminum was pressed into the preform, subsequently, cooled rapidly. In situ reaction samples were obtained by heating the as-cast material from 600 to 1000℃ for I h. The microstructural evolution of in situ reaction samples was analyzed by scanning electron microscopy and energy dispersive X-ray. In addition, the phase composition of products was inspected by X-ray diffraction. Experimental results showed that the dominant product of TiAl3 and a small amount of Al4C3 were formed at low temperature. While TiAl3 was not stable at high temperature, along with its decrease, TiC phase became favorable. In the final products, TiAl3, TiC and Al4C3 were detected. Thus, the in situ reaction for Ti-Al-C system composite proceeded a formed-decomposed-precipitated mechanism.
基金Project(2004AA5BG018) supported by the Science and Technology Development Fund of Harbin, China
文摘Al-Zn-Mg-Cu alloy is a favorable choice for aerospace applications requiring good combination of strength and toughness, which is greatly influenced by the coarse intermetallic particles. The evolution of intermetallic particles in an Al-Zn-Mg-Cu alloy during heat treatment was studied by field emission gun scanning electron microscopy (FEG-SEM) and X-ray diffractometry(XRD). The results show that there are lamellar eutectic structure (α(Al)+Mg(Zn,Al,Cu)2) and Al7Cu2Fe particles in the solidified structure. The Al7Cu2Fe particles are embedded in the eutectic structure. The content of eutectic structure decreases with the increase of holding time and disappears after 24 h. The size and morphology of Al7Cu2Fe particles exhibit no change during the heat treatment. It is found that the Al2CuMg phase is formed during the treatment at 460℃. A transformation process from the primary eutectic phase Mg(Zn,Al,Cu)2 to Al2CuMg is observed, and the transformation mechanism and kinetics are analyzed. The Al2CuMg constituents form in the primary Mg(Zn,Al,Cu)2 phase, and grow along the eutectic microstructure.
基金Supported by the National Natural Science Foundation of China under Grant No 50272057.
文摘Crystalline AusSi2/Si heterojunetion nanowires （AusSi2/SiNWs） are obtained by thermal evaporating SiO pow- ders on thick gold-coated silicon substrates in a low vacuum system. Structure analysis of the produced AusSh/Si heterojunetions is performed by employing a transmission electron microscope （TEM） and a selected area electric diffraetometer. The chemical compositions axe studied by a energy-dispersive x-ray spectroscope attached to the TEM. A two-step growth model is proposed to describe the formation of the AusSi2/SiNWs. During the first step, crystalline SiNWs are formed via a growth mechanism combining the oxide-assisted growth process with the vapour-liquid-solid model at relatively high temperature. In the second step, the temperature decreases and one segment of the preformed SiNWs reacts with the remnant Au to form single crystalline AusSi2 nanowires by a solid-liquid-solid process. The present work should be useful for the future synthesis and research of high-quality gold silicide nanowires and microelectronic devices based on the nanowires.
基金supported by the National Natural Science Foundation of China(Grant No.51603143)the Natural Science Foundation of Tianjin(Grant Nos.18JCQNJC03800&17JCZDJC37500)。
文摘Tackling fogging and microbial infection problems related to the endoscope lens remain challenges due to visual disturbances and bacterial threats to human health.Herein,highly transparent antifogging and antibacterial coatings were developed in a facile way by thermal curing of zwitterionic copolymers poly(n-butyl methacrylate-co-2-aminoethyl methacrylate-co-sulfobetaine methacrylate)s with 1,3,5-triformylbenzene.Characterizations of surface chemical composition and wettability suggested that the copolymer coatings exhibited amphiphilicity with a hydrophobic surface and internal hydrophilicity.The prepared amphiphilic coating exhibited excellent antifogging properties both in vivo and in vitro.The introduction of hydrophobic n-butyl methacrylate and cationic aminoethylmethacrylate could improve the stability and antibacterial capability of the coating.The growth inhibition rates of the coatings against Staphylococcus aureus and Escherichia coli were up to 99%and the copolymer coatings with the zwitterionic groups had low hemolytic rates less than 3%.The amphiphilic copolymer coatings combined antifogging and antibacterial properties may have a promising potential for applications in biomedical devices.
基金Project Supported by the National Natural Science Foundation of China (No. 29871014).
文摘The La(III) complex with a new amide-type tripodal ligand, 2,2,2-nitrilotris{[(2-benzylaminoformyl)- phenoxy]ethyl}amine (L), was synthesized and characterized by X-ray crystallographic analysis. Crystal data: C48H55.50LaN7O18.75, Mr=1169.40, monoclinic, space group, P21/n, a=1.0644(3) nm, b=2.3889(5) nm, c=2.1917(5) nm, b=90.65, V=5.573(2) nm3, Z=1, Dc=1.394 gcm-3, R1=0.0487, wR [I>2s(I)]=0.1266. The results reveal that each La(III) ion binds to 9 oxygen atoms, three of which belong to carbonyl groups from three tripodal ligands and six to three bidentate nitrate groups and a two-dimensional sheet of 4.82 networks is assembled by metal-ligand coordination interaction. L, a heptadentate compound, merely acts as a tridentate bridging spacer due to its steric hindrance and links the La(III) ions as three-connected nodes.
