The sodium potassium citrato oxotungstate(VI) dimer, Na 4K 2〔W 2O 5\|(cit) 2〕·11H 2O (H 4cit = citric acid) was obtained by the reaction of sodium tungstate(VI) and excess potassium citrate monobasic (KH 3cit) ...The sodium potassium citrato oxotungstate(VI) dimer, Na 4K 2〔W 2O 5\|(cit) 2〕·11H 2O (H 4cit = citric acid) was obtained by the reaction of sodium tungstate(VI) and excess potassium citrate monobasic (KH 3cit) in neutral solution. The crystal data for the title compound: monoclinic, C 12 H 30 K 2Na 4W 2O 30 , M r =1192.21, space group P2 1/n, a=17.427(4), b=10.022(2), c=18.637(3) , β=92.62(1)°, V=3252(2) 3, Z=4, D c =2.435 g/cm 3, μ( Mo Kα )=76.38 cm -1 , F( 000)=2288. The structure was refined to R =0.0434 for 6327 independent observed reflections with I>3σ(I) . The complex anion contains a quasi centrosymmetric (O 2W)O b(WO 2) core with a bent bridging oxo group 〔W-O b-W 175.0(4)°〕. Each citrate as tridentate ligand coordinates to a tungsten atom through the alkoxy, α carboxyl, and one β carboxyl group, while the other β carboxyl group remains uncoordinated. Principal dimensions are: W-O b 1.883(6) , (W=O t)av 1.715(6) , W-O (alkoxy) 1.959(6) , W-O ( α carboxy) 2.176(6) and W-O ( β carboxy) 2.231(6) . The tungsten atom is located in a distorted octahedron environment.展开更多
The doping of the spinel ferrites with selective cations usually improves the properties of the parent ferrite.The effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-...The doping of the spinel ferrites with selective cations usually improves the properties of the parent ferrite.The effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-xCoxFe2-xGdxO4 prepared by the citrate-nitrate auto-combustion synthesis was investigated.Characterization of the samples was performed with powder X-ray diffraction(XRD),Raman and Fouriertransform infrared(FTIR)spectroscopy,field-emission scanning electron microscopy,X-ray energydispersive spectroscopy,UV-Vis spectroscopy,and a vibrating sample magnetometer.The results of XRD,Raman,and FTIR analysis show a gradual structural phase transition from a tetragonal(I41/amd)structure to a cubic(Fd3m)structure.The bandgap energy of the studied samples is in a range of 1.57-1.75 eV with a minimum in sample x=0.06 and then increases.Magnetic investigations show that the presence of Co^(2+)/Gd^(3+)cations in an octahedral site of the copper ferrite structure could increase saturation magnetization and coercive field from 567.9 Oe and 23.62 emu/g to 929.4 Oe and 28.27 emu/g,respectively.展开更多
背景:柠檬酸钙作为补钙剂、抗凝剂、抗炎剂、骨修复材料等在生物医用相关领域均有良好应用。目的:描述柠檬酸钙的基本性质,总结探讨其种制备工艺方法及在生物医用领域的主要应用。方法:通过计算机在Web of science、CNKI及Medline等数...背景:柠檬酸钙作为补钙剂、抗凝剂、抗炎剂、骨修复材料等在生物医用相关领域均有良好应用。目的:描述柠檬酸钙的基本性质,总结探讨其种制备工艺方法及在生物医用领域的主要应用。方法:通过计算机在Web of science、CNKI及Medline等数据库检索与柠檬酸钙相关的研究文献,主要的检索词有"Calcium citrate,bone repairing material,Citrate and calcium phosphate,柠檬酸钙,骨修复材料",设置发表时间为1920年2月至2020年2月。结果与结论:随着医用材料的发展和探索,因性能需求而改变原来的工艺方法以提高医用柠檬酸钙的生物活性,利用条件可控的合成制备方法得到多种微观形貌、生物活性高的柠檬酸钙是一种必然趋势。柠檬酸钙的应用较广泛,例如作为补钙剂、抗炎剂、抗凝剂、骨修复材料及在一些其他非医用领域的应用,其优点正在被研究者们慢慢发掘。制备方法对于柠檬酸钙的应用领域起决定性作用,不同的内部结构和尺寸大小都会带来不一样的应用领域,从最小的化学键连接不同到宏观的形貌或者力学性能,这些因素或许正是研究者所潜心探索的结果。展开更多
This study explored the superior citrate method(CM)to synthesize Mn-Ce bi-oxides on 3 D monolithic Ni-foam(NF)catalysts for the selective catalytic reduction of NO by NH_(3)(NH_(3)-SCR).The 17 wt%Mn(7)Ce(3)O_(x)/NF(CM...This study explored the superior citrate method(CM)to synthesize Mn-Ce bi-oxides on 3 D monolithic Ni-foam(NF)catalysts for the selective catalytic reduction of NO by NH_(3)(NH_(3)-SCR).The 17 wt%Mn(7)Ce(3)O_(x)/NF(CM-17)catalyst shows the NO_(x)conversion of 98.7%at 175℃and 90%in the presence of 10 vol%H2 O.It is revealed that the combination of surface-active oxygen(formed by high-level oxygen vacancies)and strongly oxidized Mn4+species promots the Fast-SCR reactions,in which Mn4+species play a leading role in NH_(3)-SCR reaction,and the unsaturated Ni atoms and also Ce3+species promote electron exchange and thus improve the redox performance.The coexistence mechanisms of Fast-SCR reactions and E-R pathways are observed over Mn-CeO_(x)/NF catalyst,which may be promoted by the Br?nsted sites at low temperature.In addition,the heat resistance,stability,3 D monolithic porous structure and excellent physical properties of foam nickel provide a unique growth substrates for catalysts preparation and reaction sites for NO_(x)purification.Therefore,industrial application of Mn-Ce bioxides loaded on 3 D monolithic is proposed to be achieved through reasonable preparation methods.展开更多
文摘The sodium potassium citrato oxotungstate(VI) dimer, Na 4K 2〔W 2O 5\|(cit) 2〕·11H 2O (H 4cit = citric acid) was obtained by the reaction of sodium tungstate(VI) and excess potassium citrate monobasic (KH 3cit) in neutral solution. The crystal data for the title compound: monoclinic, C 12 H 30 K 2Na 4W 2O 30 , M r =1192.21, space group P2 1/n, a=17.427(4), b=10.022(2), c=18.637(3) , β=92.62(1)°, V=3252(2) 3, Z=4, D c =2.435 g/cm 3, μ( Mo Kα )=76.38 cm -1 , F( 000)=2288. The structure was refined to R =0.0434 for 6327 independent observed reflections with I>3σ(I) . The complex anion contains a quasi centrosymmetric (O 2W)O b(WO 2) core with a bent bridging oxo group 〔W-O b-W 175.0(4)°〕. Each citrate as tridentate ligand coordinates to a tungsten atom through the alkoxy, α carboxyl, and one β carboxyl group, while the other β carboxyl group remains uncoordinated. Principal dimensions are: W-O b 1.883(6) , (W=O t)av 1.715(6) , W-O (alkoxy) 1.959(6) , W-O ( α carboxy) 2.176(6) and W-O ( β carboxy) 2.231(6) . The tungsten atom is located in a distorted octahedron environment.
文摘The doping of the spinel ferrites with selective cations usually improves the properties of the parent ferrite.The effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-xCoxFe2-xGdxO4 prepared by the citrate-nitrate auto-combustion synthesis was investigated.Characterization of the samples was performed with powder X-ray diffraction(XRD),Raman and Fouriertransform infrared(FTIR)spectroscopy,field-emission scanning electron microscopy,X-ray energydispersive spectroscopy,UV-Vis spectroscopy,and a vibrating sample magnetometer.The results of XRD,Raman,and FTIR analysis show a gradual structural phase transition from a tetragonal(I41/amd)structure to a cubic(Fd3m)structure.The bandgap energy of the studied samples is in a range of 1.57-1.75 eV with a minimum in sample x=0.06 and then increases.Magnetic investigations show that the presence of Co^(2+)/Gd^(3+)cations in an octahedral site of the copper ferrite structure could increase saturation magnetization and coercive field from 567.9 Oe and 23.62 emu/g to 929.4 Oe and 28.27 emu/g,respectively.
文摘背景:柠檬酸钙作为补钙剂、抗凝剂、抗炎剂、骨修复材料等在生物医用相关领域均有良好应用。目的:描述柠檬酸钙的基本性质,总结探讨其种制备工艺方法及在生物医用领域的主要应用。方法:通过计算机在Web of science、CNKI及Medline等数据库检索与柠檬酸钙相关的研究文献,主要的检索词有"Calcium citrate,bone repairing material,Citrate and calcium phosphate,柠檬酸钙,骨修复材料",设置发表时间为1920年2月至2020年2月。结果与结论:随着医用材料的发展和探索,因性能需求而改变原来的工艺方法以提高医用柠檬酸钙的生物活性,利用条件可控的合成制备方法得到多种微观形貌、生物活性高的柠檬酸钙是一种必然趋势。柠檬酸钙的应用较广泛,例如作为补钙剂、抗炎剂、抗凝剂、骨修复材料及在一些其他非医用领域的应用,其优点正在被研究者们慢慢发掘。制备方法对于柠檬酸钙的应用领域起决定性作用,不同的内部结构和尺寸大小都会带来不一样的应用领域,从最小的化学键连接不同到宏观的形貌或者力学性能,这些因素或许正是研究者所潜心探索的结果。
基金Project supported by the National Key R&D Program of China(2017YFC0210303)National Natural Science Foundation of China(21806009)+1 种基金China Postdoctoral Science Foundation(2019T120049)Fundamental Research Funds for the Central Universities(06500152,FRF-TP-18-019A1)。
文摘This study explored the superior citrate method(CM)to synthesize Mn-Ce bi-oxides on 3 D monolithic Ni-foam(NF)catalysts for the selective catalytic reduction of NO by NH_(3)(NH_(3)-SCR).The 17 wt%Mn(7)Ce(3)O_(x)/NF(CM-17)catalyst shows the NO_(x)conversion of 98.7%at 175℃and 90%in the presence of 10 vol%H2 O.It is revealed that the combination of surface-active oxygen(formed by high-level oxygen vacancies)and strongly oxidized Mn4+species promots the Fast-SCR reactions,in which Mn4+species play a leading role in NH_(3)-SCR reaction,and the unsaturated Ni atoms and also Ce3+species promote electron exchange and thus improve the redox performance.The coexistence mechanisms of Fast-SCR reactions and E-R pathways are observed over Mn-CeO_(x)/NF catalyst,which may be promoted by the Br?nsted sites at low temperature.In addition,the heat resistance,stability,3 D monolithic porous structure and excellent physical properties of foam nickel provide a unique growth substrates for catalysts preparation and reaction sites for NO_(x)purification.Therefore,industrial application of Mn-Ce bioxides loaded on 3 D monolithic is proposed to be achieved through reasonable preparation methods.
