The CuZrAl bulk metallic glass with minor-addition of Fe was prepared by rapid quenching method. The structures were examined by X-ray diffraction (XRD). The effect of Fe on the glass-forming ability was studied by ...The CuZrAl bulk metallic glass with minor-addition of Fe was prepared by rapid quenching method. The structures were examined by X-ray diffraction (XRD). The effect of Fe on the glass-forming ability was studied by differential scanning calorimetry (DSC). The minor-addition of Fe obviously extends the supercooled liquid region ΔTx. The plastic strain of the Cu44Zr48Al7Fe bulk metallic glass is about 1.5%. The microstructures were examined by transmission electron microscopy (TEM). It is found that when 1%-2% Fe (mole fraction) were introduced into the CuZrAl alloy matrix, nanoscale phase separation occurs in the as-prepared Cu44Zr48Al7Fe bulk metallic glass.展开更多
The Aronia melanocarpa El oit was used as test material. The microstruc-ture of normal and vitrified shoots and the characteristics of their stomas on leaf surface were compared by paraffin section and leaf epidermis-...The Aronia melanocarpa El oit was used as test material. The microstruc-ture of normal and vitrified shoots and the characteristics of their stomas on leaf surface were compared by paraffin section and leaf epidermis-tearing method. The results showed the palisade tissue of Aronia melanocarpa El oit consists of 2-3 lay-ers of cells. The stomas on lower epidermis cave in, and are smal and dense. There are abundant vessels and sieve tubes in stems. ln contrast, the main veins of vitrified shoots are unobvious, messy and irregular. The boundary between pal-isade tissue and spongy tissue is not obvious. The stomas open circularly and bigly. The stems are swel ing and thick, but the pith parenchyma cells are broken.展开更多
Mechanical properties of (Cu50Zr43Al7)100 Nbx (x=0,1,3,6,9) bulk metallic glasses rods with a diameter of 2.5 mm prepared by suction casting method were studied. The results of uniaxial compression tests at room t...Mechanical properties of (Cu50Zr43Al7)100 Nbx (x=0,1,3,6,9) bulk metallic glasses rods with a diameter of 2.5 mm prepared by suction casting method were studied. The results of uniaxial compression tests at room temperture show that the best mechanical properties of 2.8% and 1.98 GPa for plastic strain and fracture strength, respectively, in the sample with x=3. Microstructure, fracture surface and shear bands of the samples were observed by SEM and XRD methods.展开更多
The effects of Al2O3 addition on both the sintering behavior and microwave dielectric properties of PbO-B203-SiO2 glass ceramics were investigated by Fourier transform infrared spectroscope (FTIR), differential ther...The effects of Al2O3 addition on both the sintering behavior and microwave dielectric properties of PbO-B203-SiO2 glass ceramics were investigated by Fourier transform infrared spectroscope (FTIR), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that with the increase of Al2O3 content the bands assigned to [SiO4] nearly disappear. Aluminum replaces silicon in the glass network, which is helpful for the formation of boron-oxygen rings. The increase of the transition temperature Tg and softening temperature Tf of PbO-B2O3-SiO2 glass ceramics leads to the increase of liquid phase precipitation temperature and promotes the structure stability in the glasses, and consequently contributes to the decreasing trend of crystallization. Densification and dielectric constants increase with the increase of Al2O3 content, but the dielectric loss is worsened. By contrast, the 3% (mass fraction) Al2O3-doped glass ceramics sintered at 725℃ have better properties of density p=2.72 g/cm3, dielectric constant Er=6.78, dielectric loss tan8=2.6×10^-3 (measured at 9.8 GHz), which suggest that the glass ceramics can be applied in multilayer microwave devices requiring low sintering temperatures.展开更多
Based on the harmonic vibration equation, the relationship between IR characteristic peak of fiberglass and Si-O-Si bond angle was deduced, and 1 100 cm^-1 characteristic peak was specifically studied. It is found tha...Based on the harmonic vibration equation, the relationship between IR characteristic peak of fiberglass and Si-O-Si bond angle was deduced, and 1 100 cm^-1 characteristic peak was specifically studied. It is found that 1 100 cm^-1 characteristic peak shifts to higher wave number when Si-O-Si bond angle increases. Taking fused biconical taper (FBT) coupler as an example, the microstructures of the fiber coupler manufactured at different draw- ing speeds were tested with micro infrared spectrum. According to the test results, it is found that the bond angle at the taper region is the largest, the one at the fused region is the second largest, and the one of bare fiber is the smal- lest. The characteristic peaks of fused-taper region shift to higher wave number when drawing speed increases.展开更多
SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investiga...SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investigated by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction and three-point bending method. The results show that ZrO2 is not an effective nucleating agent in SiO2-Al2O3-ZrO2 system, while TiO2 is effective for the separation of spinel, and P2O5 facilitates solubility of ZrO2 in glass and crystallization. The main crystalline phases of the glass-ceramics are spinel, anorthite and tetragonal zirconia. With the increase of ZrO2 content in the glass, glass-ceramics show higher bending strength (120MPa) than others.展开更多
The effects of B2O3 addition on both the sintering behavior and microwave dielectric properties of CaO-B2O3-SiO2 (CBS) glass ceramics were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diff...The effects of B2O3 addition on both the sintering behavior and microwave dielectric properties of CaO-B2O3-SiO2 (CBS) glass ceramics were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results show that the increasing amount of B203 causes the increase of the contents of [BO3], [BO4] and [SiO4], which deduces the increase of CaB204 and a-SiO2 and the decrease of CaSiO3 correspondingly. No new phase is observed throughout the entire experiments. A bulk density of 2.54 g/cm3, a thermal expansion coefficient value of 11.95× 10-6 ℃-1 (20-500℃), a dielectric constant er value of 6.42 and a dielectric loss tanδ value of 0.000 9 (measured at 9.7 GHz) are obtained for CBS glass ceramics containing 35%-B203 (mass fraction) sintered at 850 ℃ for 15 min.展开更多
The effects of ZrO2 on the crystallinity of mica and microstructure of a machina- ble glassceramic were studied. It was found that ZrO2 is an effective nucleation agent in mica glass- ceramics. Stabilized by Ca2+, a l...The effects of ZrO2 on the crystallinity of mica and microstructure of a machina- ble glassceramic were studied. It was found that ZrO2 is an effective nucleation agent in mica glass- ceramics. Stabilized by Ca2+, a lot of t--ZrO2 particles precipitate from ZrO2-mica glass-ceramics. The ZrO2 particles can effectively limit the growth of mica crystal and benefit the mechanical properties of glass-ceramics.展开更多
The structure and dielectric properties of (Pb,Sr)Nb2O6-NaNbO3-SiO2 glass-ceramics with different Pb and Sr contents were investigated. The XRD pattern of glass-ceramics without Sr substitution is different from tha...The structure and dielectric properties of (Pb,Sr)Nb2O6-NaNbO3-SiO2 glass-ceramics with different Pb and Sr contents were investigated. The XRD pattern of glass-ceramics without Sr substitution is different from that with Sr substitution, which indicates the existence of orthorhombic phase in the latter ones. TEM bright field observation shows nanosized microstructures, while for samples with Sr, typical eutectic microstrncture with separated crystallized bands is found in the glass matrix. Dielectric properties measurement of the samples indicates an obvious improvement of dielectric constant, dielectric loss, DC field and temperature dependence of dielectric constant when the molar ratio of Sr to Pb is 4:6.展开更多
Low-temperature sintering and properties of LTCC (low temperature co-fired ceramics) materials based on CaO-BaO-Al2O3-B2O3-SiO2 glass and various fillers such as Al2O3, silica glass, christobalite, AlN, ZrO2, MgO-Si...Low-temperature sintering and properties of LTCC (low temperature co-fired ceramics) materials based on CaO-BaO-Al2O3-B2O3-SiO2 glass and various fillers such as Al2O3, silica glass, christobalite, AlN, ZrO2, MgO-SiO2, TiO2 were investigated. The results show that densification, crystallization, microstructures and dielectric properties of the composites are found to strongly depend on the type of filler. The densification process of glass/ceramic composites with various fillers is mainly from 600 ℃ to 925 ℃, and the initial compacting temperature of samples is 600 ℃. The initial rapid densification of samples starts at its glass softening temperature. LTCC compositions containing Al2O3, silica glass, AlN and MgO-SiO2 fillers start to have the crystallization peaks at 890, 903, 869 and 844 ℃, respectively. The crystallization peaks are believed as correlated to the crystallization of CaAl2SiO8, β-SiO2, Ca2Al2SiO7 and β-SiO2. The composite ceramic with Al2O3, silica glass and TiO2 ceramic have a better dense structure and better smooth fracture surface. Sample for Al2O3 has the lowest dielectric loss tanδ value of 0.00091, whereas the sample for MgO.SiO, has the highest dielectric loss tanδ value of 0.02576. The sample for TiO2 has the highest dielectric constant value of 14.46, whereas the sample for AIN has the lowest dielectric constant value of 4.61.展开更多
Molecular dynamics(MD) simulations were performed to investigate the glass forming ability(GFA) and microscopic structural properties of liquid Cu-Zr alloys.Based on the analysis of composition dependences of the redu...Molecular dynamics(MD) simulations were performed to investigate the glass forming ability(GFA) and microscopic structural properties of liquid Cu-Zr alloys.Based on the analysis of composition dependences of the reduced glass transition temperatures and the excess volume,we found that the Cu-Zr glasses have the largest GFA at Cu65Zr35 composition.To get more detailed information of local structure,we calculated the pair correlation functions,partial pair correlation functions,the excess entropy,chemical order parameter,coordination number,and Voronoi index of Cu-Zr liquids.We found that there exists an obvious and close relationship among the GFA,the excess entropy calculated using the total pair correlation functions,chemical order parameters,and some Cu centered cluster with Voronoi index <0,2,8,1> and Zr centered cluster with Voronoi index <0,3,6,4>,which all have nonlinear dependences on Cu/Zr concentration and have extreme values at liquid Cu65Zr35 composition.展开更多
Co5 Sm/Cr bilayer films were deposited on Si and glass slides by means of a Direct-Current (DC) magnetron sputtering system with substrate heating. Magnetic properties measurements show that the sample with glass su...Co5 Sm/Cr bilayer films were deposited on Si and glass slides by means of a Direct-Current (DC) magnetron sputtering system with substrate heating. Magnetic properties measurements show that the sample with glass substrate has a comparatively large coercivity (He = 2 141.20e) with a rela- tively low optimal temperature ( Ts =350 ℃ ). X-ray diffraction patterns indicate that Cr presents a hexagonal-close-packed (hcp) texture on Si, while a body-centered-cubic (bcc) struc- ture on glass substrate, which leads to Cos Sm films having dif- ferent lattice constants on Si and glass substrates. At their opti- mal temperature, the grain size of the sample on glass slide is smaller with its size distribution more uniform. Concurrently, the shape of magnetic domain is more regular and ordered. The value of magnetic switching volume ( V ) for the film on glass is 1.65×10-18 cm3 , smaller than that for films on Si. For the film on glass, the magnetization reversal mechanism is mainly influenced by magnetocrystalline anisotropy, the shape of the crystal grain and the stress in the film.展开更多
Objective: The aim of the study was to observe and compare the effects of cryopreservation and thawing meth- ods on rat ovarian tissues. Methods: Twenty 5-6 weeks old SPF-SD female rats were randomly divided into two ...Objective: The aim of the study was to observe and compare the effects of cryopreservation and thawing meth- ods on rat ovarian tissues. Methods: Twenty 5-6 weeks old SPF-SD female rats were randomly divided into two groups, with ten rats in each group. Freshly isolated ovaries saved as a control (group 1: fresh ovaries) in formalin-fixed or vitrified immediately after dissection (group 2: vitrified ovaries). Ovaries in vitrified group were processed into thin slices then cryo- preserved, stored in liquid nitrogen for 21 days, rapidly thawed and grossly examined. All of the collected ovaries underwent hematoxylin and eosin-stained paraffin serial sections and observed the microscopic evaluation in vitrified ovaries. Results: Grossly the vitrified ovaries turned pale color and the size was same as before freeze. The vitrified ovarian tissue had normal anatomical structures of cortex and medulla under the microscope and had no difference with the fresh control ovarian tis- sue. The number and distribution of the follicles were similar with the fresh ovarian tissue, but had smaller size and the gap between oocyte and the surrounding granulosa cells was increased. Few ooctyes were in irregular appearance however the morphology of follicular cells did not give a different appearance as compared to the fresh control ovarian tissue. Conclusion: Cryopreservation of ovarian tissues by vitrification method has some detrimental effect on the morphology of follicles but does not induce negative impact on the number, density and survival of the primordial ovarian follicles. However the whole follicle anatomical structures also had no significant changes.展开更多
Gas-atomized powders of three Fe-based glass-forming alloys were sprayed on mild steel substrates by atmospheric plasma spaying using the same spaying parameters. Microstructures, thermal stabilities and tribological ...Gas-atomized powders of three Fe-based glass-forming alloys were sprayed on mild steel substrates by atmospheric plasma spaying using the same spaying parameters. Microstructures, thermal stabilities and tribological properties of the sprayed coatings were analyzed. The coating performances showed a strong dependence on the intrinsic characters of the compositions, i.e., glass-forming ability (GFA) and supercooled liquid region (ATx). The coatings tended to exhibit higher amorphous phase fraction for the composition with higher GFA and lower porosity for that with larger ATX. All the coatings exhibited superior wear resistance compared with the substrate. Higher wear resistance could be obtained in coatings with higher amorphous phase fraction, i.e. higher GFA of the composition. This study has important implications for composition selecting and optimizing in the fabrication of metallic glass coatings.展开更多
A facile,precise,and controllable manufacturing technology is desired for hierarchical functional surfaces.In this work,we successfully manufactured porous metallic glass using a water-dissolution material as template...A facile,precise,and controllable manufacturing technology is desired for hierarchical functional surfaces.In this work,we successfully manufactured porous metallic glass using a water-dissolution material as template and the excellent thermoplastic property of metallic glass.The prepared micro/nanostructures have excellent tunability,and the proposed approach can be used to prepare large-area disordered porous structures and ordered regular arrays with nanoscale replication accuracy.In particular,the disordered porous structure prepared by the dissolvable template strategy exhibits a water contact angle of~140°and an oil contact angle of~0°,making it suitable for oil/water separation.It also shows stable wettability after being soaked in strong acid or alkali environments and maintains a~130°water contact angle and a~4°oil contact angle even after severe wear.The proposed strategy also possesses excellent recycling properties.We reconstructed porous structures on the same surface three times and found no significant change in wettability for each reconstructed porous structure.Our research provides a facile and controllable approach for the preparation of hierarchical porous structures and paves the way for the design of other functional surfaces.展开更多
基金Project (2010ZDJH10) supported by the Nanjing University of Science and Technology Research Funding, ChinaProject (BK2007213) supported by the Natural Science Foundation of Jiangsu Province, China
文摘The CuZrAl bulk metallic glass with minor-addition of Fe was prepared by rapid quenching method. The structures were examined by X-ray diffraction (XRD). The effect of Fe on the glass-forming ability was studied by differential scanning calorimetry (DSC). The minor-addition of Fe obviously extends the supercooled liquid region ΔTx. The plastic strain of the Cu44Zr48Al7Fe bulk metallic glass is about 1.5%. The microstructures were examined by transmission electron microscopy (TEM). It is found that when 1%-2% Fe (mole fraction) were introduced into the CuZrAl alloy matrix, nanoscale phase separation occurs in the as-prepared Cu44Zr48Al7Fe bulk metallic glass.
文摘The Aronia melanocarpa El oit was used as test material. The microstruc-ture of normal and vitrified shoots and the characteristics of their stomas on leaf surface were compared by paraffin section and leaf epidermis-tearing method. The results showed the palisade tissue of Aronia melanocarpa El oit consists of 2-3 lay-ers of cells. The stomas on lower epidermis cave in, and are smal and dense. There are abundant vessels and sieve tubes in stems. ln contrast, the main veins of vitrified shoots are unobvious, messy and irregular. The boundary between pal-isade tissue and spongy tissue is not obvious. The stomas open circularly and bigly. The stems are swel ing and thick, but the pith parenchyma cells are broken.
文摘Mechanical properties of (Cu50Zr43Al7)100 Nbx (x=0,1,3,6,9) bulk metallic glasses rods with a diameter of 2.5 mm prepared by suction casting method were studied. The results of uniaxial compression tests at room temperture show that the best mechanical properties of 2.8% and 1.98 GPa for plastic strain and fracture strength, respectively, in the sample with x=3. Microstructure, fracture surface and shear bands of the samples were observed by SEM and XRD methods.
基金Project(2007AA03Z0455) supported by the National High Technology Research and Development Program of ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institution, China
文摘The effects of Al2O3 addition on both the sintering behavior and microwave dielectric properties of PbO-B203-SiO2 glass ceramics were investigated by Fourier transform infrared spectroscope (FTIR), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that with the increase of Al2O3 content the bands assigned to [SiO4] nearly disappear. Aluminum replaces silicon in the glass network, which is helpful for the formation of boron-oxygen rings. The increase of the transition temperature Tg and softening temperature Tf of PbO-B2O3-SiO2 glass ceramics leads to the increase of liquid phase precipitation temperature and promotes the structure stability in the glasses, and consequently contributes to the decreasing trend of crystallization. Densification and dielectric constants increase with the increase of Al2O3 content, but the dielectric loss is worsened. By contrast, the 3% (mass fraction) Al2O3-doped glass ceramics sintered at 725℃ have better properties of density p=2.72 g/cm3, dielectric constant Er=6.78, dielectric loss tan8=2.6×10^-3 (measured at 9.8 GHz), which suggest that the glass ceramics can be applied in multilayer microwave devices requiring low sintering temperatures.
基金Project(50235040) supported bythe National Natural Science Foundation of China project(NCET-040753) supported bythe New Century Excellent Talents in University project(20050533037) supported by the research fund for the Doctoral Program ofHigher Education
文摘Based on the harmonic vibration equation, the relationship between IR characteristic peak of fiberglass and Si-O-Si bond angle was deduced, and 1 100 cm^-1 characteristic peak was specifically studied. It is found that 1 100 cm^-1 characteristic peak shifts to higher wave number when Si-O-Si bond angle increases. Taking fused biconical taper (FBT) coupler as an example, the microstructures of the fiber coupler manufactured at different draw- ing speeds were tested with micro infrared spectrum. According to the test results, it is found that the bond angle at the taper region is the largest, the one at the fused region is the second largest, and the one of bare fiber is the smal- lest. The characteristic peaks of fused-taper region shift to higher wave number when drawing speed increases.
文摘SiO2-Al2O3-ZrO2 glasses with different nucleating agents were crystallized under special processing schedule. The microstructure and mechanical properties of the glass-ceramics in SiO2-Al2O3-ZrO2 system were investigated by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction and three-point bending method. The results show that ZrO2 is not an effective nucleating agent in SiO2-Al2O3-ZrO2 system, while TiO2 is effective for the separation of spinel, and P2O5 facilitates solubility of ZrO2 in glass and crystallization. The main crystalline phases of the glass-ceramics are spinel, anorthite and tetragonal zirconia. With the increase of ZrO2 content in the glass, glass-ceramics show higher bending strength (120MPa) than others.
基金Project(2007AA03Z0455) supported by the National High-Technology Research and Development Program of ChinaProject(BE2009168) supported by the Natural Science Foundation of Jiangsu Province in ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institution,China
文摘The effects of B2O3 addition on both the sintering behavior and microwave dielectric properties of CaO-B2O3-SiO2 (CBS) glass ceramics were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results show that the increasing amount of B203 causes the increase of the contents of [BO3], [BO4] and [SiO4], which deduces the increase of CaB204 and a-SiO2 and the decrease of CaSiO3 correspondingly. No new phase is observed throughout the entire experiments. A bulk density of 2.54 g/cm3, a thermal expansion coefficient value of 11.95× 10-6 ℃-1 (20-500℃), a dielectric constant er value of 6.42 and a dielectric loss tanδ value of 0.000 9 (measured at 9.7 GHz) are obtained for CBS glass ceramics containing 35%-B203 (mass fraction) sintered at 850 ℃ for 15 min.
基金the Trans-Century Training Program Foundation for the Talents by the Ministry of Education of China the National Natural Science Foundation of China (No. 50172010) and Natural Science Foundation of Liaoning Province (No. 20
文摘The effects of ZrO2 on the crystallinity of mica and microstructure of a machina- ble glassceramic were studied. It was found that ZrO2 is an effective nucleation agent in mica glass- ceramics. Stabilized by Ca2+, a lot of t--ZrO2 particles precipitate from ZrO2-mica glass-ceramics. The ZrO2 particles can effectively limit the growth of mica crystal and benefit the mechanical properties of glass-ceramics.
文摘The structure and dielectric properties of (Pb,Sr)Nb2O6-NaNbO3-SiO2 glass-ceramics with different Pb and Sr contents were investigated. The XRD pattern of glass-ceramics without Sr substitution is different from that with Sr substitution, which indicates the existence of orthorhombic phase in the latter ones. TEM bright field observation shows nanosized microstructures, while for samples with Sr, typical eutectic microstrncture with separated crystallized bands is found in the glass matrix. Dielectric properties measurement of the samples indicates an obvious improvement of dielectric constant, dielectric loss, DC field and temperature dependence of dielectric constant when the molar ratio of Sr to Pb is 4:6.
基金Project supported by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions ChinaProject(CXZZ12_0415) supported by Innovation Foundation for Graduate Students of Jiangsu Province ChinaProject(IRT1146) supported by Changjiang Scholars and Innovative Research Team in University(PCSIRT),China
文摘Low-temperature sintering and properties of LTCC (low temperature co-fired ceramics) materials based on CaO-BaO-Al2O3-B2O3-SiO2 glass and various fillers such as Al2O3, silica glass, christobalite, AlN, ZrO2, MgO-SiO2, TiO2 were investigated. The results show that densification, crystallization, microstructures and dielectric properties of the composites are found to strongly depend on the type of filler. The densification process of glass/ceramic composites with various fillers is mainly from 600 ℃ to 925 ℃, and the initial compacting temperature of samples is 600 ℃. The initial rapid densification of samples starts at its glass softening temperature. LTCC compositions containing Al2O3, silica glass, AlN and MgO-SiO2 fillers start to have the crystallization peaks at 890, 903, 869 and 844 ℃, respectively. The crystallization peaks are believed as correlated to the crystallization of CaAl2SiO8, β-SiO2, Ca2Al2SiO7 and β-SiO2. The composite ceramic with Al2O3, silica glass and TiO2 ceramic have a better dense structure and better smooth fracture surface. Sample for Al2O3 has the lowest dielectric loss tanδ value of 0.00091, whereas the sample for MgO.SiO, has the highest dielectric loss tanδ value of 0.02576. The sample for TiO2 has the highest dielectric constant value of 14.46, whereas the sample for AIN has the lowest dielectric constant value of 4.61.
基金Funded by the National Natural Science Foundation of China (Grant Nos. 11074253,10874182 and 50803066)the Foundation of the Education Committee of Anhui Province,China (Grant Nos. KJ2010A031 and KJ2010A012)
文摘Molecular dynamics(MD) simulations were performed to investigate the glass forming ability(GFA) and microscopic structural properties of liquid Cu-Zr alloys.Based on the analysis of composition dependences of the reduced glass transition temperatures and the excess volume,we found that the Cu-Zr glasses have the largest GFA at Cu65Zr35 composition.To get more detailed information of local structure,we calculated the pair correlation functions,partial pair correlation functions,the excess entropy,chemical order parameter,coordination number,and Voronoi index of Cu-Zr liquids.We found that there exists an obvious and close relationship among the GFA,the excess entropy calculated using the total pair correlation functions,chemical order parameters,and some Cu centered cluster with Voronoi index <0,2,8,1> and Zr centered cluster with Voronoi index <0,3,6,4>,which all have nonlinear dependences on Cu/Zr concentration and have extreme values at liquid Cu65Zr35 composition.
基金supported by National Science Foundation of China(10804026)Natural Science Foundation of Hebei Province(E2010000429)Foundation of Hebei Educational Committee(2006123)
文摘Co5 Sm/Cr bilayer films were deposited on Si and glass slides by means of a Direct-Current (DC) magnetron sputtering system with substrate heating. Magnetic properties measurements show that the sample with glass substrate has a comparatively large coercivity (He = 2 141.20e) with a rela- tively low optimal temperature ( Ts =350 ℃ ). X-ray diffraction patterns indicate that Cr presents a hexagonal-close-packed (hcp) texture on Si, while a body-centered-cubic (bcc) struc- ture on glass substrate, which leads to Cos Sm films having dif- ferent lattice constants on Si and glass substrates. At their opti- mal temperature, the grain size of the sample on glass slide is smaller with its size distribution more uniform. Concurrently, the shape of magnetic domain is more regular and ordered. The value of magnetic switching volume ( V ) for the film on glass is 1.65×10-18 cm3 , smaller than that for films on Si. For the film on glass, the magnetization reversal mechanism is mainly influenced by magnetocrystalline anisotropy, the shape of the crystal grain and the stress in the film.
文摘Objective: The aim of the study was to observe and compare the effects of cryopreservation and thawing meth- ods on rat ovarian tissues. Methods: Twenty 5-6 weeks old SPF-SD female rats were randomly divided into two groups, with ten rats in each group. Freshly isolated ovaries saved as a control (group 1: fresh ovaries) in formalin-fixed or vitrified immediately after dissection (group 2: vitrified ovaries). Ovaries in vitrified group were processed into thin slices then cryo- preserved, stored in liquid nitrogen for 21 days, rapidly thawed and grossly examined. All of the collected ovaries underwent hematoxylin and eosin-stained paraffin serial sections and observed the microscopic evaluation in vitrified ovaries. Results: Grossly the vitrified ovaries turned pale color and the size was same as before freeze. The vitrified ovarian tissue had normal anatomical structures of cortex and medulla under the microscope and had no difference with the fresh control ovarian tis- sue. The number and distribution of the follicles were similar with the fresh ovarian tissue, but had smaller size and the gap between oocyte and the surrounding granulosa cells was increased. Few ooctyes were in irregular appearance however the morphology of follicular cells did not give a different appearance as compared to the fresh control ovarian tissue. Conclusion: Cryopreservation of ovarian tissues by vitrification method has some detrimental effect on the morphology of follicles but does not induce negative impact on the number, density and survival of the primordial ovarian follicles. However the whole follicle anatomical structures also had no significant changes.
基金supported by the National Basic Research Program of China (Grant No. 2007CB613900)the National Natural Science Foundation of China (Grant No. 51071008)the Fundamental Research Funds for the Central Universities
文摘Gas-atomized powders of three Fe-based glass-forming alloys were sprayed on mild steel substrates by atmospheric plasma spaying using the same spaying parameters. Microstructures, thermal stabilities and tribological properties of the sprayed coatings were analyzed. The coating performances showed a strong dependence on the intrinsic characters of the compositions, i.e., glass-forming ability (GFA) and supercooled liquid region (ATx). The coatings tended to exhibit higher amorphous phase fraction for the composition with higher GFA and lower porosity for that with larger ATX. All the coatings exhibited superior wear resistance compared with the substrate. Higher wear resistance could be obtained in coatings with higher amorphous phase fraction, i.e. higher GFA of the composition. This study has important implications for composition selecting and optimizing in the fabrication of metallic glass coatings.
基金supported by the Key Basic and Applied Research Program of Guangdong Province,China(2019B030302010)the National Natural Science Foundation of China(52122105,51871157,and 51971150)the National Key Research and Development Program of China(2018YFA0703604)。
文摘A facile,precise,and controllable manufacturing technology is desired for hierarchical functional surfaces.In this work,we successfully manufactured porous metallic glass using a water-dissolution material as template and the excellent thermoplastic property of metallic glass.The prepared micro/nanostructures have excellent tunability,and the proposed approach can be used to prepare large-area disordered porous structures and ordered regular arrays with nanoscale replication accuracy.In particular,the disordered porous structure prepared by the dissolvable template strategy exhibits a water contact angle of~140°and an oil contact angle of~0°,making it suitable for oil/water separation.It also shows stable wettability after being soaked in strong acid or alkali environments and maintains a~130°water contact angle and a~4°oil contact angle even after severe wear.The proposed strategy also possesses excellent recycling properties.We reconstructed porous structures on the same surface three times and found no significant change in wettability for each reconstructed porous structure.Our research provides a facile and controllable approach for the preparation of hierarchical porous structures and paves the way for the design of other functional surfaces.