By the minor addition of Nb to a Mg-Cu-Ag-Gd alloy,a Mg-Cu-Ag-Gd-Nb bulk metallic glass （BMG） with improved thermal stability and corrosion resistance as well as good mechanical properties was developed.Mg54Cu26.5Ag...By the minor addition of Nb to a Mg-Cu-Ag-Gd alloy,a Mg-Cu-Ag-Gd-Nb bulk metallic glass （BMG） with improved thermal stability and corrosion resistance as well as good mechanical properties was developed.Mg54Cu26.5Ag8.5Gd11-xNbx （x=0,1） BMGs with a diameter of 2 mm were fabricated by copper-mold casting.The Mg54Cu26.5Ag8.5Gd10Nb1 BMG exhibits enlarged supercooled liquid region of 58 K.Electrochemical measurements indicate that the addition of Nb improves the corrosion resistance of the Mg-based BMG in NaCl solution evidenced by the increased corrosion potential,though no significant effect of Nb on the corrosion behavior of the BMG in NaOH solution is observed.The Mg-Cu-Ag-Gd-Nb BMG also shows high compressive strength up to 890 MPa and elastic strain of about 1.9%.展开更多
Bulk metallic glass composites （BMGCs） reinforced by micro- （spherical size of about 10 gin） and nano-sized （20-50 nm） A13Zr crystals were synthesized by copper mold suction casting method. The isothermal crysta...Bulk metallic glass composites （BMGCs） reinforced by micro- （spherical size of about 10 gin） and nano-sized （20-50 nm） A13Zr crystals were synthesized by copper mold suction casting method. The isothermal crystallization of Cu4oZr44AgsAls BMGCs in the super- cooled liquid region was studied by differential scanning calorimeter （DSC）, X-ray diffractometer （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The mechanisms for nucleation and growth of the crystalline phases precipitated in two-stage crystallization process and the effect of the isothermal treatment on the in situ crystalline phases were discussed. Results show that the BMGCs experience a primary crys- tallization process. Nano-sized A13Zr and Cul0Zr7 phases precipitate from the amorphous matrix successively. Fur- thermore, isothermal annealing has no effect on the pre- existing particles in the as-cast sample, which creates a new method to synthesize BMGCs strengthened by duplex crystalline phases with a large size difference. And the reinforced phase could also be dominated with intention if the as-cast BMGCs preparation and isothermal treatment process can be controlled more accurately.展开更多
A novel open-framework vanadium(W) phosphate(H_3NCH_2CH_2NH_3)_3[(VO)_4(PP_4)_2(HPO_4)_4] (short for V_2P_3-en) has been prepared. It issynthesized hydrothermally in the presence of ethylenediamine (en) at 170 deg C f...A novel open-framework vanadium(W) phosphate(H_3NCH_2CH_2NH_3)_3[(VO)_4(PP_4)_2(HPO_4)_4] (short for V_2P_3-en) has been prepared. It issynthesized hydrothermally in the presence of ethylenediamine (en) at 170 deg C for 5 days byself-assembly from structurally simple precursors V_2O_5, H_3PO_4 and H_2O. The compound ischaracterized by means of Fourier transform-infrared spectroscopy (FT-IR),Thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction analysis (XRD) andScanning electron microscopy (SEM). Furthermore, the composition-structure-thermal stabilityrelation of V_2P_3-en is explored in terms of crystal chemistry, and the potential approach to theenhancement of its thermal stability is proposed.展开更多
Nd60All0Co30-xNix （x=0, 5, 10 and 15 at. pct） metallic glasses have been prepared using single-spinner and suck-casting method, and characterized using X-ray diffrac- tion （XRD） and non-isothermal differential sca...Nd60All0Co30-xNix （x=0, 5, 10 and 15 at. pct） metallic glasses have been prepared using single-spinner and suck-casting method, and characterized using X-ray diffrac- tion （XRD） and non-isothermal differential scanning calorimetric technique. It has been found that the Mloy with 15 at. pct Ni has the strongest glass forming ability, and can be fabricated to a rod with 5 mm in diameter using suck-casting. The addition of Ni has an obvious effect on the thermal behavior of the metallic glasses, especially on the position of the second and third crystallization peaks. The crystallization ki- netics and activation energies of the four metallic glasses have been elaborated using the Kissinger equation. The continuous heating transformation curves of the T~ and Tpl have been constructed by applying the extension of the Vogel-Fulcher-Tammann （VFT） nonlinear equations, which are derived from the experimental data in the heat- ing rate range of 5-80 K/min. The effect of Ni on the formation and thermal stability of the Nd-based metallic glasses has been discussed.展开更多
Using the entangled state representation, we convert a two-mode squeezed number state to a Hermite polynomial excited squeezed vacuum state. We first analytically derive the photon number distribution of the two-mode ...Using the entangled state representation, we convert a two-mode squeezed number state to a Hermite polynomial excited squeezed vacuum state. We first analytically derive the photon number distribution of the two-mode squeezed thermal states. It is found that it is a Jacobi polynomial; a remarkable result. This result can be directly applied to obtaining the photon number distribution of non-Gaussian states generated by subtracting from （adding to） two-mode squeezed thermal states.展开更多
Trehalose is a widely used and safe natural disaccharide.Maltooligosyl trehalose hydrolase(MTHase)is one of the key enzymes for trehalose preparation by double enzyme method using starch or dextrin as substrate.In ind...Trehalose is a widely used and safe natural disaccharide.Maltooligosyl trehalose hydrolase(MTHase)is one of the key enzymes for trehalose preparation by double enzyme method using starch or dextrin as substrate.In industrial production,the thermalstability of MTHase is of great significance.We first heterogeneously expressed MTHase from Arthrobacter in E.coli strains BL21(DE3).Based on the overall stability of the protein after virtual saturation mutation predicted by FoldX and the evolutionary information from PSSM,15 mutations were selected and combined.Finally,the combinatorial mutant G589P/A57P was obtained.At 60℃,the t_(1/2)of G589P/A57P and wild type are 37 min and 19 min,respectively,which is 1.9 times higher than that of wild type.The enzyme kinetic parameters of G589P/A57P were analyzed.The K_(M)and k_(cat)are 4.82 mM and 1136 s^(−1),respectively,and the results were close to the wild type,indicating that the mutation did not reduce the catalytic efficiency of the enzyme.The molecular dynamics simulation results show that the rigidity and thermal stability of G589P/A57P protein increase in the range of residues 50-100 and 400-500,which may be due to the proline effect caused by the introduction of proline.展开更多
基金financially supported by the Natural Science Foundation of Beijing(No.2132045)
文摘By the minor addition of Nb to a Mg-Cu-Ag-Gd alloy,a Mg-Cu-Ag-Gd-Nb bulk metallic glass （BMG） with improved thermal stability and corrosion resistance as well as good mechanical properties was developed.Mg54Cu26.5Ag8.5Gd11-xNbx （x=0,1） BMGs with a diameter of 2 mm were fabricated by copper-mold casting.The Mg54Cu26.5Ag8.5Gd10Nb1 BMG exhibits enlarged supercooled liquid region of 58 K.Electrochemical measurements indicate that the addition of Nb improves the corrosion resistance of the Mg-based BMG in NaCl solution evidenced by the increased corrosion potential,though no significant effect of Nb on the corrosion behavior of the BMG in NaOH solution is observed.The Mg-Cu-Ag-Gd-Nb BMG also shows high compressive strength up to 890 MPa and elastic strain of about 1.9%.
基金financially supported by the National Natural Science Foundation of China (Nos.51061008 and 50961008)
文摘Bulk metallic glass composites （BMGCs） reinforced by micro- （spherical size of about 10 gin） and nano-sized （20-50 nm） A13Zr crystals were synthesized by copper mold suction casting method. The isothermal crystallization of Cu4oZr44AgsAls BMGCs in the super- cooled liquid region was studied by differential scanning calorimeter （DSC）, X-ray diffractometer （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The mechanisms for nucleation and growth of the crystalline phases precipitated in two-stage crystallization process and the effect of the isothermal treatment on the in situ crystalline phases were discussed. Results show that the BMGCs experience a primary crys- tallization process. Nano-sized A13Zr and Cul0Zr7 phases precipitate from the amorphous matrix successively. Fur- thermore, isothermal annealing has no effect on the pre- existing particles in the as-cast sample, which creates a new method to synthesize BMGCs strengthened by duplex crystalline phases with a large size difference. And the reinforced phase could also be dominated with intention if the as-cast BMGCs preparation and isothermal treatment process can be controlled more accurately.
基金This research was kindly supported by the Research Fund for the Doctoral Program of Higher Education (RFDP) and the OpeningFou
文摘A novel open-framework vanadium(W) phosphate(H_3NCH_2CH_2NH_3)_3[(VO)_4(PP_4)_2(HPO_4)_4] (short for V_2P_3-en) has been prepared. It issynthesized hydrothermally in the presence of ethylenediamine (en) at 170 deg C for 5 days byself-assembly from structurally simple precursors V_2O_5, H_3PO_4 and H_2O. The compound ischaracterized by means of Fourier transform-infrared spectroscopy (FT-IR),Thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction analysis (XRD) andScanning electron microscopy (SEM). Furthermore, the composition-structure-thermal stabilityrelation of V_2P_3-en is explored in terms of crystal chemistry, and the potential approach to theenhancement of its thermal stability is proposed.
基金supported by the SRF for ROCS(State Education Ministry)the Fundamental Research Funds for the Central University,P.R.China(Grant Nos.N100409001 and N090209001)
文摘Nd60All0Co30-xNix （x=0, 5, 10 and 15 at. pct） metallic glasses have been prepared using single-spinner and suck-casting method, and characterized using X-ray diffrac- tion （XRD） and non-isothermal differential scanning calorimetric technique. It has been found that the Mloy with 15 at. pct Ni has the strongest glass forming ability, and can be fabricated to a rod with 5 mm in diameter using suck-casting. The addition of Ni has an obvious effect on the thermal behavior of the metallic glasses, especially on the position of the second and third crystallization peaks. The crystallization ki- netics and activation energies of the four metallic glasses have been elaborated using the Kissinger equation. The continuous heating transformation curves of the T~ and Tpl have been constructed by applying the extension of the Vogel-Fulcher-Tammann （VFT） nonlinear equations, which are derived from the experimental data in the heat- ing rate range of 5-80 K/min. The effect of Ni on the formation and thermal stability of the Nd-based metallic glasses has been discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11047133, 60978009, and 10774088)the Major Research Plan of the National Natural Science Foundation of China (Grant No. 91121023)+2 种基金the "973" Project (Grant No. 2011CBA00200)the Natural Science Foundation of Jiangxi Province of China (No. 2010GQW0027)the Sponsored Program for Cultivating Youths of Outstanding Ability in Jiangxi Normal University
文摘Using the entangled state representation, we convert a two-mode squeezed number state to a Hermite polynomial excited squeezed vacuum state. We first analytically derive the photon number distribution of the two-mode squeezed thermal states. It is found that it is a Jacobi polynomial; a remarkable result. This result can be directly applied to obtaining the photon number distribution of non-Gaussian states generated by subtracting from （adding to） two-mode squeezed thermal states.
基金supported by the National Natural Science Foundation of China(No.32171471)Key Research and Development Project of Shandong Province,China(2019JZZY020605)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,Top-notch Academic Programs Project of Jiangsu Higher Education Institutions.
文摘Trehalose is a widely used and safe natural disaccharide.Maltooligosyl trehalose hydrolase(MTHase)is one of the key enzymes for trehalose preparation by double enzyme method using starch or dextrin as substrate.In industrial production,the thermalstability of MTHase is of great significance.We first heterogeneously expressed MTHase from Arthrobacter in E.coli strains BL21(DE3).Based on the overall stability of the protein after virtual saturation mutation predicted by FoldX and the evolutionary information from PSSM,15 mutations were selected and combined.Finally,the combinatorial mutant G589P/A57P was obtained.At 60℃,the t_(1/2)of G589P/A57P and wild type are 37 min and 19 min,respectively,which is 1.9 times higher than that of wild type.The enzyme kinetic parameters of G589P/A57P were analyzed.The K_(M)and k_(cat)are 4.82 mM and 1136 s^(−1),respectively,and the results were close to the wild type,indicating that the mutation did not reduce the catalytic efficiency of the enzyme.The molecular dynamics simulation results show that the rigidity and thermal stability of G589P/A57P protein increase in the range of residues 50-100 and 400-500,which may be due to the proline effect caused by the introduction of proline.
