Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the r...Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization.Here,we developed a solution inverse temperature crystal growth(ITCG)method to bring-up high quality Cs_(3)Cu_(2)I_(5)crystals with large size of centimeter order,in which the oleic acid(OA)is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently,as well as to decelerate the crystallization rate remarkalby.Based on these fine crystals,the vapor deposition technique is empolyed to prepare high quality Cs_(3)Cu_(2)I_(5)films for efficient X-ray imaging.Smooth surface morphology,high light yields and short decay time endow the Cs_(3)Cu_(2)I_(5)films with strong radioluminescence,high resolution(12 lp/mm),low detection limits(53 nGyair/s)and desirable stability.Subsequently,the Cs_(3)Cu_(2)I_(5)films have been applied to the practical radiography which exhibit superior X-ray imaging performance.Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.展开更多
Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6...Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6-anhydro-β-maltoses, a thiocyanate ion and a sodium ion, was identified in the crystal of the complex, where a sodium ion was positioned in the center of the pentagon. In the NMR study, the line broadening of 23Na signals and the decrease of the spin-lattice relaxation times (T1) of 23Na were observed in CD3OD in the presence of 1,6-anhydro-β-maltose, indicating complex formation.展开更多
To clarify the correlation of single-crystalline structure with corrosion performance in high-strength TiAl alloys, electrochemical and surface characterization was performed by comparing Ti–45Al–8Nb dual-phase sing...To clarify the correlation of single-crystalline structure with corrosion performance in high-strength TiAl alloys, electrochemical and surface characterization was performed by comparing Ti–45Al–8Nb dual-phase single crystals with their polycrystalline counterparts in NaCl solution. Polarization curves show a lower corrosion rate and a higher pitting potential of ~280 mV for the dual-phase single crystals. Electrochemical impedance spectroscopy and potentiostatic polarization plots revealed a higher impedance of the charge transfer through the compact passive film. Surface composition analysis indicated a compact film with more content of Nb, as twice as that in the film on the polycrystals.Our results reflect that the dual-phase Ti–45Al–8Nb single crystals possess a higher corrosion resistance in NaCl solution, compared with their polycrystalline counterpart, arising from a more homogeneous microstructure and composition distribution.展开更多
Based on the relief of interfacial energy density by dislocation generation at the gamma - gamma ' interfaces, a rafting prediction criterion has been developed for nickel-base single crystals under multiaxial str...Based on the relief of interfacial energy density by dislocation generation at the gamma - gamma ' interfaces, a rafting prediction criterion has been developed for nickel-base single crystals under multiaxial stresses. The diagrams of rafting have been presented, and confirmed by experimental results. The rafting process have been analyzed quantitatively by the relief of interfacial energy. The criterion has been applied to study the creep behavior. The example of creep life analysis shows that the criterion can be correlated greatly to the crystallographic orientation dependence of creep behavior. (Author abstract) 11 Refs.展开更多
The high quality single crystals of Yb5Co4Ge10 have been grown by the indium metal flux method and characterized by means of single crystal X-ray diffraction data. Yb5Co4Ge10 crystallizes in the Sc5Co4Si10 structure t...The high quality single crystals of Yb5Co4Ge10 have been grown by the indium metal flux method and characterized by means of single crystal X-ray diffraction data. Yb5Co4Ge10 crystallizes in the Sc5Co4Si10 structure type, tetragonal space group P4/mbm and lattice constants are a = b = 12.6369(18) ? and c = 4.1378(8) ?. Crystal structure of Yb5Co4Ge10 composed of three-dimensional [Co4Ge12] network having five, six and eight membered rings. The three non-equivalent Yb atoms are sandwiched in three different channels created by the [Co4Ge12] network. Based on the bond length analysis from the crystallographic information, we confirmed that Yb1 and Yb2 atoms are in the trivalent magnetic state and Yb3 is in the divalent non-magnetic state.展开更多
In this research KCl, KCl:Mn, KCl:Ag and KCl:In single crystals have been grown by Czochralski method. X-ray diffraction confirms KCl single crystal formation. In this work also influence of mentioned impurities on th...In this research KCl, KCl:Mn, KCl:Ag and KCl:In single crystals have been grown by Czochralski method. X-ray diffraction confirms KCl single crystal formation. In this work also influence of mentioned impurities on the optical property of KCl single crystal has been studied by chemical etching. Then the hardness of these crystals have been measured by Vickers micro hardness. The result indicate the positive effect of the impurity on optical and mechanical properties.展开更多
Single crystals of undoped and nickel-doped BaFe2-xNixAs2 (x = 0, 0.04) have been grown by FeAs self-flux method. The maximum dimension of the crystal is as large as - 1 cm along ab plane. The crystalline topography...Single crystals of undoped and nickel-doped BaFe2-xNixAs2 (x = 0, 0.04) have been grown by FeAs self-flux method. The maximum dimension of the crystal is as large as - 1 cm along ab plane. The crystalline topography of a cleaved crystal surface is examined by scanning electron microscope (SEM). By x-ray powder diffraction (XRD) experiments using pure silicon as an internal standard, precise unit cell parameters (tetragonal at room temperature) are determined: a = 3.9606(4) A^°. (1 A^°=0.1 nm), c = 13.015(2) A^°. for BaFe1.96Ni0.04As2 and a = 3.9590(5) A^°, c = 13.024(1) A^°for BaFe2As2. DC magnetization and transport measurements are performed to check superconducting transition (Tc = 15 K for x = 0.04) and other subtle anomalies. For BaFe1.96Ni0.04As2 crystal, the resistance curve at normal state shows two distinct anomalies associated with spin and structure transitions, and its magnetization data above - 91 K exhibit a linear temperature dependence due to spin density wave (SDW) instability.展开更多
Non-linear optical materials find wide range of applications in the fields of opto-electronics, fiber optic communication, computer memory devices etc. Tris-Glycine Zinc Chloride (TGZC) is one of the NLO materials exh...Non-linear optical materials find wide range of applications in the fields of opto-electronics, fiber optic communication, computer memory devices etc. Tris-Glycine Zinc Chloride (TGZC) is one of the NLO materials exhibiting more efficiency. In the present study Tris-Glycine Zinc Chloride were grown is single crystal form using slow evaporation technique. Single crystal X-ray diffraction analysis reveals that the crystal belongs to orthorhombic system with the space group Pbn21. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut off wavelength of 250 nm. The optical band gap is found to be 4.60 eV. The dependence of extinction coefficient (K) and refractive index (n) on the wavelength has also been reported. Force constants (k) were calculated using FTIR spectral analysis which shows higher values of k for COO and C=O stretching vibrations. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures (35℃, 55℃, 75℃ and 95℃).展开更多
A new alkali metallo-organic single crystal of Lithium Sodium Acid Phthlate (LiNaP) complex has been synthesized from aqueous solution in the equimolar ratio 3:1:2. Transparent and bulk single crystals of dimension 9 ...A new alkali metallo-organic single crystal of Lithium Sodium Acid Phthlate (LiNaP) complex has been synthesized from aqueous solution in the equimolar ratio 3:1:2. Transparent and bulk single crystals of dimension 9 × 4 ×2 mm3 have been grown from the conventional slow-cooling technique. The crystal structure of the compound has been solved from single crystal X-ray diffraction. The compound 2[C8H4O3]4-Li3+Na+ crystallizes in triclinic system with a space group of Pī having cell dimensions a = 7.5451(2) ? b = 9.8422(3) ? c = 25.2209(7) ? α = 80.299(2);β = 89.204(2);γ = 82.7770(10). FTIR measurement was carried out fo? LiNaP to study the vibrational structure of the compound. The various functional groups present in the molecule and the role of H-bonds in stabilizing the crystal structure of the compound have been explained. Optical absorption properties were studied for the grown crystal using UV-Vis-NIR spectrum. Thermal measurements were carried out for LiNaP to determine the thermal strength as well as to ascertain the hydrated nature of the crystal. Third order nonliner optical studies have also studied by Z-scan techniques. Nonlinear absorption and nonlinear refractive index were found out and the third order bulk susceptibility of compound was also estimated. The results of all studies have been discussed in detail.展开更多
New metal complexes of N-benzyl-N-nitrosohy-droxylamine (BNHA) are isolated and characterized by elemental analysis, IR and UV-VIS spectroscopy. Spectrophotometric titration of aqueous solutions of BNHА by salts of s...New metal complexes of N-benzyl-N-nitrosohy-droxylamine (BNHA) are isolated and characterized by elemental analysis, IR and UV-VIS spectroscopy. Spectrophotometric titration of aqueous solutions of BNHА by salts of some transition metals allowed to calculate the composition and formation constants of the metal complexes. The crystal structure of Cu (BNHА)2 is studied by X-ray diffraction. The Cu atom is coordinated by four O atoms of two bidentate ligands, which close 5-membered chelate rings. The N-O (1.306 ? - 1.320 ?) and N-N (1.274?? and 1.275? ) bond lengths indicate that π electrons are delocalized over the chelating groups. Complexes form stacks with intermolecular Cu…N contacts equal to 3.118?? and 3.306 ?.展开更多
New transition metal complex of Cobalt(III) of the ligand (E)-3-(1-(2-aminoethylimino)ethyl)-4-hydroxy-2H-chromen-2-one, derived from condensation of ethylene diamine with 3-acetyl-4-hydroxy-chromene-2-one have been s...New transition metal complex of Cobalt(III) of the ligand (E)-3-(1-(2-aminoethylimino)ethyl)-4-hydroxy-2H-chromen-2-one, derived from condensation of ethylene diamine with 3-acetyl-4-hydroxy-chromene-2-one have been synthesized by reaction of cobalt(III) salt and the ligand, in amounts equal to metal-ligand molar ratio of 1:2. Both the Schiff base and the complex of Co(III) were characterized by IR, UV-Vis, 1H NMR- and 13C NMR-spectroscopy techniques. Single crystal X-ray diffraction investigation, at low temperature T = 120 K, shows that the cobalt complex is triclinic P-1, a = 10.426(5) ?, b = 11.3234(2) ?, c = 15.729(5) ?, α(°) = 70.102(4), β(°) = 86.049(4), γ(°) = 82.497(4), Z = 2, and its structure consists of isolated [Co(III)(C13H13N2O3)2]+ complex cations with distorted octahedral geometry, ClO-4 counter anions, acetone solvent and water molecules. The crystal cohesion is stabilized by hydrogen bonds between ligands and water molecules, and ionic interactions between complex cations and counter anions.展开更多
A new family of photochromic diarylethene compounds, 1-(2-methyl-5-formyl-3- thienyl)-2-(2-methoxylphenyl)perfluorocyclopentene (1o) having an unsymmetrically substituted hexafluorocyclopentene unit, was synthes...A new family of photochromic diarylethene compounds, 1-(2-methyl-5-formyl-3- thienyl)-2-(2-methoxylphenyl)perfluorocyclopentene (1o) having an unsymmetrically substituted hexafluorocyclopentene unit, was synthesized and its structure was determined. The crystal belongs to the monoclinic system, space group P21/c with a = 15.4866(5), b = 9.0744(9), c = 12.6906(3), β = 90.1480(10)°, Z = 4, V = 1783.4(3)3, Dc = 1.513 mg/m3, μ = 0.25, F(000) = 824, the final R = 0.0579 and wR = 0.1566 for 2584 observed reflections (I 2σ(I)). Interestingly, a colorless compound 1o undergoes photocyclization upon irradiation of UV light to give the blue isomer diarylethene. Upon irradiation with visible light with wavelength greater than 510 nm, the blue compound can return to its initial colorless state.展开更多
Structural genomics (SG) is an international effort that aims at solving three-dimensional shapes of important biological macro-molecules with primary focus on proteins. One of the main bottlenecks in SG is the abilit...Structural genomics (SG) is an international effort that aims at solving three-dimensional shapes of important biological macro-molecules with primary focus on proteins. One of the main bottlenecks in SG is the ability to produce dif-fraction quality crystals for X-ray crystallogra-phy based protein structure determination. SG pipelines allow for certain flexibility in target selection which motivates development of in- silico methods for sequence-based prediction/ assessment of the protein crystallization pro-pensity. We overview existing SG databanks that are used to derive these predictive models and we discuss analytical results concerning protein sequence properties that were discov-ered to correlate with the ability to form crystals. We also contrast and empirically compare mo- dern sequence-based predictors of crystalliza-tion propensity including OB-Score, ParCrys, XtalPred and CRYSTALP2. Our analysis shows that these methods provide useful and compli-mentary predictions. Although their average ac- curacy is similar at around 70%, we show that application of a simple majority-vote based en-semble improves accuracy to almost 74%. The best improvements are achieved by combining XtalPred with CRYSTALP2 while OB-Score and ParCrys methods overlap to a larger extend, although they still complement the other two predictors. We also demonstrate that 90% of the protein chains can be correctly predicted by at least one of these methods, which suggests that more accurate ensembles could be built in the future. We believe that current protein crystalli-zation propensity predictors could provide useful input for the target selection procedures utilized by the SG centers.展开更多
A new family of photochromic diarylethene compounds, 1-(2-cyano-l,5-dimethyl- 4-pyrryl)-2-[2-methyl-5-(3-pyridyl)-3-thienyl]perfluorocyclopentene (lo) having an unsymmetrical pyrryl and thienyl substituted hexaf...A new family of photochromic diarylethene compounds, 1-(2-cyano-l,5-dimethyl- 4-pyrryl)-2-[2-methyl-5-(3-pyridyl)-3-thienyl]perfluorocyclopentene (lo) having an unsymmetrical pyrryl and thienyl substituted hexafluorocyclopentene unit, was synthesized and its structure was determined by X-ray analysis. The crystal belongs to triclinic system, space group PI with a = 8.897(7), b = 10.139(8), c = 12.361(9) A, α = 85.222(7), ρ = 75.439(7), γ = 78.736(8)°, Z = 2, V= 1057.8(14) A3, D,.= 1.468 mg/m3, p = 0.220 mm-1, F(000) = 476, the final R = 0.0608 and wR = 0.1754 for 3199 observed reflections (1 〉20(/)). Interestingly, compound 1 exhibits good photochromic properties with alternate irradiation of UV light and visible light (〉 510 nm) to form two photoisomers in hexane solution and crystal phase.展开更多
1-Phenyl-2-acetoxy-2-methyl-propanone, a new a-hydroxy ketone derivative, was synthesized by Friedel-Crafts acylation and characterized by FT-IR, 1H NMR, MS spectra and single-crystal X-ray diffraction measurements. T...1-Phenyl-2-acetoxy-2-methyl-propanone, a new a-hydroxy ketone derivative, was synthesized by Friedel-Crafts acylation and characterized by FT-IR, 1H NMR, MS spectra and single-crystal X-ray diffraction measurements. The data are as follows: monoclinic, space group P21/c, Z = 4, C12H1403, Mr = 206.24, a = 8.9430(2), b =15.2680(4), c = 8.2550(2) A, β = 91.9650(5)°, V = 1126.60(5)A^3, Dc = 1.216 g/cm^3, μ(MoKα) = 0.087 mm^-1, F(000) = 440, R = 0.0725 and wR = 0.1379 for 1282 observed reflections with I〉 2σ(I). The structure was solved by direct methods and refined by full-matrix least-squares refinement on F2 methods. The benzene ring in the structure is almost coplanar with the adjacent carbonyl groups and t-carbonyl atom. Meanwhile, the long chain is approximately perpendicular to the plane. X-ray analysis reveals that the crystal structure involves two weak intramolecular C-H…O hydrogen bonds.展开更多
Four cytotoxic oxazolidin-2-one derivatives were prepared from alkynyl alcohol and isocynate with high yields of 83~95%, and their structures were characterized by IR, H-RESI-MS and NMR analysis. Meanwhile, the cryst...Four cytotoxic oxazolidin-2-one derivatives were prepared from alkynyl alcohol and isocynate with high yields of 83~95%, and their structures were characterized by IR, H-RESI-MS and NMR analysis. Meanwhile, the crystal of (Z)-4-benzylidene-3-ethyl-1-oxa-3-azaspiro[4.4] nonan-2-one (5a) was obtained and determined by X-ray single-crystal diffraction. Crystal data: monoclinic system, space group P121/c1, a = 10.9284(2), b = 9.47510(10), c = 14.2510(2) ?, β = 111.917(2)o, V = 1369.01(3) ?3, Z = 4, F(000) = 552.0, Dc = 1.248 Mg/m3, μ = 0.652 mm-1, R = 0.0473 and wR = 0.1207 for 2699 independent reflections (Rint = 0.0206) and 2581 observed ones (I 〉 2σ(I)).展开更多
A new photochromic diarylethene, [1-(2-methyl-5-(4-cyanophenyl)-3-thienyl-2- (2-methyl-5-phenyl-3-thienyl)]perfluorocyclopentene (lo, C28H17F6NS2), was synthesized and its structure was determined by single-cry...A new photochromic diarylethene, [1-(2-methyl-5-(4-cyanophenyl)-3-thienyl-2- (2-methyl-5-phenyl-3-thienyl)]perfluorocyclopentene (lo, C28H17F6NS2), was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. Its crystal belongs to the monoclinic system, space group P21/c with a = 24.1381(5), b = 9.3834(6), c = 11.1073(8), fl = 94.477(4)°, Z = 4, V= 2508.1(3) A3, Dc = 1.445 mg/m3, μ = 0.275, F(000) = 1112, the final R = 0.0482 and wR = 0.1429 for 5834 observed reflections (I 〉 2σ(I)). Further study demonstrated the diarylethene underwent reversible photochromism, changing between colorless and blue in hexane solution, crystalline phase and PMMA films, respectively.展开更多
In the Bi-Sr-Ca-Cu-O superconductor system, two superconducting phases (85K and 105K) were found by Maeda et al. By substituting Pb, enhanced superconducting properties and structure stabilization in these compounds h...In the Bi-Sr-Ca-Cu-O superconductor system, two superconducting phases (85K and 105K) were found by Maeda et al. By substituting Pb, enhanced superconducting properties and structure stabilization in these compounds have been reported. Recently, the展开更多
8,9,12-Trihydro-9,9-pentamethylene- 12-(3-nitrophenyl)- 11H-naphtho[ 1',25,6]- pyrano[2,3-d]pyfimidin- 11 (10H)-one 1, another conversion product of Ffiedlandler reaction, has been synthesized by the reaction of ...8,9,12-Trihydro-9,9-pentamethylene- 12-(3-nitrophenyl)- 11H-naphtho[ 1',25,6]- pyrano[2,3-d]pyfimidin- 11 (10H)-one 1, another conversion product of Ffiedlandler reaction, has been synthesized by the reaction of 2-amino-4-(3-nitrophenyl)-4H-benzo[f]chromene-3-carbonitrile 2 with cyclohexanone in the presence of Lewis acid catalysts. The crystal of the title compound 1 THF solvate, C60H62N6O10, was obtained and determined by X-ray diffraction method. The crystal is of triclinic, space group P1 with a = 11.4633(11), b = 12.6247(12), c = 19.658(2)A, α = 72.642(8), β = 89.045(9), γ = 68.340(5)°, V = 2509.6(4), Z = 2, De = 1.359 g/cm^3, F(000) = 1088, Mr = 1027.16, the final R = 0.0674 and wR = 0.1869 with Ⅰ 〉 2σ(Ⅰ) and the goodness-of-fit S = 1.045 on F^2. The pyrimidine ring has an envelope conformation, linked with a six-membered ring through a spiro C atom. The crystal packing of 1 THF solvate is stabilized by N-H…O hydrogen bonds, and π-π stacking interaction occurs between two adjacent nearly planar molecules of 1.展开更多
The crystal structure of fused photochromic diarylethene dimer, 1,4-bis-[4-(4-{2-(5-phenyl)-2-methyl-thiophen-3-yl]-3,3,4,4,5,5-hexafluoro-cyclopent-1-enyl}-5-methyl-thiophen-2-yl) buta-1,3-diyne(1 oo, C46 H23 F12 S4)...The crystal structure of fused photochromic diarylethene dimer, 1,4-bis-[4-(4-{2-(5-phenyl)-2-methyl-thiophen-3-yl]-3,3,4,4,5,5-hexafluoro-cyclopent-1-enyl}-5-methyl-thiophen-2-yl) buta-1,3-diyne(1 oo, C46 H23 F12 S4) was determined by single-crystal X-ray diffraction analysis. This crystal belongs to the triclinic system, space group P1 with a = 7.546(3), b = 8.869(3), c = 16.196(5), α = 98.000(4)°, β = 100.803(4)°, γ = 98.449(4)°, Z = 2, V = 1037.6(6) ?~3, Dc = 1.496 mg/m^3, μ = 0.317, F(000) = 474, the final R = 0.0428 and wR = 0.1199 for 4115 observed reflections(I > 2σ(I)). Further study demonstrated this compound underwent reversible photochromism with color-switching between colorlessness and green in crystalline state. Upon 365 nm irradiation, the diarylethene shows one step photochromism to form isomer 1 oc. When irradiated with 312 nm, the stepwise photocyclization reactions occurred in diarylethene dimer through the line of 1 oo to 1 oc to 1 cc.展开更多
基金the financially support of the National Natural Science Foundation of China(12164051)the Joint Foundation of Provincial Science and Technology Department-Double First-class Construction of Yunnan University(2019FY003016)+4 种基金the Young Top Talent Project of Yunnan Province(YNWR-QNBJ-2018-229)the financially support by Yunnan Major Scientific and Technological Projects(202202AG050016)Advanced Analysis and Measurement Center of Yunnan University for the sample characterization service and the Postgraduate Research and Innovation Foundation of Yunnan University(2021Y036)the financially support of the National Natural Science Foundation of China(62064013)the Application Basic Research Project of Yunnan Province[2019FB130]。
文摘Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization.Here,we developed a solution inverse temperature crystal growth(ITCG)method to bring-up high quality Cs_(3)Cu_(2)I_(5)crystals with large size of centimeter order,in which the oleic acid(OA)is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently,as well as to decelerate the crystallization rate remarkalby.Based on these fine crystals,the vapor deposition technique is empolyed to prepare high quality Cs_(3)Cu_(2)I_(5)films for efficient X-ray imaging.Smooth surface morphology,high light yields and short decay time endow the Cs_(3)Cu_(2)I_(5)films with strong radioluminescence,high resolution(12 lp/mm),low detection limits(53 nGyair/s)and desirable stability.Subsequently,the Cs_(3)Cu_(2)I_(5)films have been applied to the practical radiography which exhibit superior X-ray imaging performance.Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.
文摘Complex formation of 1,6-anhydro-β-maltose and sodium ions was characterized using single-crystal X-ray crystallography and solution- and solid-state NMR spectroscopy. The 7-coordination structure, comprising two 1,6-anhydro-β-maltoses, a thiocyanate ion and a sodium ion, was identified in the crystal of the complex, where a sodium ion was positioned in the center of the pentagon. In the NMR study, the line broadening of 23Na signals and the decrease of the spin-lattice relaxation times (T1) of 23Na were observed in CD3OD in the presence of 1,6-anhydro-β-maltose, indicating complex formation.
基金financially supported by the CityU internal supports under “The Structural Material Development Funding” program (No. CityU 7004894)National Natural Science Foundation of China (Nos. 51901086 and 51731006)Natural Science Foundation of Jiangsu Province, China (Nos. BK20190977 and BK 20180984)。
文摘To clarify the correlation of single-crystalline structure with corrosion performance in high-strength TiAl alloys, electrochemical and surface characterization was performed by comparing Ti–45Al–8Nb dual-phase single crystals with their polycrystalline counterparts in NaCl solution. Polarization curves show a lower corrosion rate and a higher pitting potential of ~280 mV for the dual-phase single crystals. Electrochemical impedance spectroscopy and potentiostatic polarization plots revealed a higher impedance of the charge transfer through the compact passive film. Surface composition analysis indicated a compact film with more content of Nb, as twice as that in the film on the polycrystals.Our results reflect that the dual-phase Ti–45Al–8Nb single crystals possess a higher corrosion resistance in NaCl solution, compared with their polycrystalline counterpart, arising from a more homogeneous microstructure and composition distribution.
文摘Based on the relief of interfacial energy density by dislocation generation at the gamma - gamma ' interfaces, a rafting prediction criterion has been developed for nickel-base single crystals under multiaxial stresses. The diagrams of rafting have been presented, and confirmed by experimental results. The rafting process have been analyzed quantitatively by the relief of interfacial energy. The criterion has been applied to study the creep behavior. The example of creep life analysis shows that the criterion can be correlated greatly to the crystallographic orientation dependence of creep behavior. (Author abstract) 11 Refs.
文摘The high quality single crystals of Yb5Co4Ge10 have been grown by the indium metal flux method and characterized by means of single crystal X-ray diffraction data. Yb5Co4Ge10 crystallizes in the Sc5Co4Si10 structure type, tetragonal space group P4/mbm and lattice constants are a = b = 12.6369(18) ? and c = 4.1378(8) ?. Crystal structure of Yb5Co4Ge10 composed of three-dimensional [Co4Ge12] network having five, six and eight membered rings. The three non-equivalent Yb atoms are sandwiched in three different channels created by the [Co4Ge12] network. Based on the bond length analysis from the crystallographic information, we confirmed that Yb1 and Yb2 atoms are in the trivalent magnetic state and Yb3 is in the divalent non-magnetic state.
文摘In this research KCl, KCl:Mn, KCl:Ag and KCl:In single crystals have been grown by Czochralski method. X-ray diffraction confirms KCl single crystal formation. In this work also influence of mentioned impurities on the optical property of KCl single crystal has been studied by chemical etching. Then the hardness of these crystals have been measured by Vickers micro hardness. The result indicate the positive effect of the impurity on optical and mechanical properties.
基金Project supported by the State Key Development Program for Basic Research of China(Grant No.2006CB601002)the National Natural Science Foundation of China(Grant Nos.10734120 and 10874211)
文摘Single crystals of undoped and nickel-doped BaFe2-xNixAs2 (x = 0, 0.04) have been grown by FeAs self-flux method. The maximum dimension of the crystal is as large as - 1 cm along ab plane. The crystalline topography of a cleaved crystal surface is examined by scanning electron microscope (SEM). By x-ray powder diffraction (XRD) experiments using pure silicon as an internal standard, precise unit cell parameters (tetragonal at room temperature) are determined: a = 3.9606(4) A^°. (1 A^°=0.1 nm), c = 13.015(2) A^°. for BaFe1.96Ni0.04As2 and a = 3.9590(5) A^°, c = 13.024(1) A^°for BaFe2As2. DC magnetization and transport measurements are performed to check superconducting transition (Tc = 15 K for x = 0.04) and other subtle anomalies. For BaFe1.96Ni0.04As2 crystal, the resistance curve at normal state shows two distinct anomalies associated with spin and structure transitions, and its magnetization data above - 91 K exhibit a linear temperature dependence due to spin density wave (SDW) instability.
文摘Non-linear optical materials find wide range of applications in the fields of opto-electronics, fiber optic communication, computer memory devices etc. Tris-Glycine Zinc Chloride (TGZC) is one of the NLO materials exhibiting more efficiency. In the present study Tris-Glycine Zinc Chloride were grown is single crystal form using slow evaporation technique. Single crystal X-ray diffraction analysis reveals that the crystal belongs to orthorhombic system with the space group Pbn21. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut off wavelength of 250 nm. The optical band gap is found to be 4.60 eV. The dependence of extinction coefficient (K) and refractive index (n) on the wavelength has also been reported. Force constants (k) were calculated using FTIR spectral analysis which shows higher values of k for COO and C=O stretching vibrations. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures (35℃, 55℃, 75℃ and 95℃).
文摘A new alkali metallo-organic single crystal of Lithium Sodium Acid Phthlate (LiNaP) complex has been synthesized from aqueous solution in the equimolar ratio 3:1:2. Transparent and bulk single crystals of dimension 9 × 4 ×2 mm3 have been grown from the conventional slow-cooling technique. The crystal structure of the compound has been solved from single crystal X-ray diffraction. The compound 2[C8H4O3]4-Li3+Na+ crystallizes in triclinic system with a space group of Pī having cell dimensions a = 7.5451(2) ? b = 9.8422(3) ? c = 25.2209(7) ? α = 80.299(2);β = 89.204(2);γ = 82.7770(10). FTIR measurement was carried out fo? LiNaP to study the vibrational structure of the compound. The various functional groups present in the molecule and the role of H-bonds in stabilizing the crystal structure of the compound have been explained. Optical absorption properties were studied for the grown crystal using UV-Vis-NIR spectrum. Thermal measurements were carried out for LiNaP to determine the thermal strength as well as to ascertain the hydrated nature of the crystal. Third order nonliner optical studies have also studied by Z-scan techniques. Nonlinear absorption and nonlinear refractive index were found out and the third order bulk susceptibility of compound was also estimated. The results of all studies have been discussed in detail.
文摘New metal complexes of N-benzyl-N-nitrosohy-droxylamine (BNHA) are isolated and characterized by elemental analysis, IR and UV-VIS spectroscopy. Spectrophotometric titration of aqueous solutions of BNHА by salts of some transition metals allowed to calculate the composition and formation constants of the metal complexes. The crystal structure of Cu (BNHА)2 is studied by X-ray diffraction. The Cu atom is coordinated by four O atoms of two bidentate ligands, which close 5-membered chelate rings. The N-O (1.306 ? - 1.320 ?) and N-N (1.274?? and 1.275? ) bond lengths indicate that π electrons are delocalized over the chelating groups. Complexes form stacks with intermolecular Cu…N contacts equal to 3.118?? and 3.306 ?.
文摘New transition metal complex of Cobalt(III) of the ligand (E)-3-(1-(2-aminoethylimino)ethyl)-4-hydroxy-2H-chromen-2-one, derived from condensation of ethylene diamine with 3-acetyl-4-hydroxy-chromene-2-one have been synthesized by reaction of cobalt(III) salt and the ligand, in amounts equal to metal-ligand molar ratio of 1:2. Both the Schiff base and the complex of Co(III) were characterized by IR, UV-Vis, 1H NMR- and 13C NMR-spectroscopy techniques. Single crystal X-ray diffraction investigation, at low temperature T = 120 K, shows that the cobalt complex is triclinic P-1, a = 10.426(5) ?, b = 11.3234(2) ?, c = 15.729(5) ?, α(°) = 70.102(4), β(°) = 86.049(4), γ(°) = 82.497(4), Z = 2, and its structure consists of isolated [Co(III)(C13H13N2O3)2]+ complex cations with distorted octahedral geometry, ClO-4 counter anions, acetone solvent and water molecules. The crystal cohesion is stabilized by hydrogen bonds between ligands and water molecules, and ionic interactions between complex cations and counter anions.
基金Supported by the Project of Natural Science Foundation of Jiangxi Province(2010GZH0040,2010GQH0039)the Project of Jiangxi Youth Scientist,and Science Funds of the Education Office of Jiangxi Province(2010DQ00200,GJJ1067,GJJ11690)
文摘A new family of photochromic diarylethene compounds, 1-(2-methyl-5-formyl-3- thienyl)-2-(2-methoxylphenyl)perfluorocyclopentene (1o) having an unsymmetrically substituted hexafluorocyclopentene unit, was synthesized and its structure was determined. The crystal belongs to the monoclinic system, space group P21/c with a = 15.4866(5), b = 9.0744(9), c = 12.6906(3), β = 90.1480(10)°, Z = 4, V = 1783.4(3)3, Dc = 1.513 mg/m3, μ = 0.25, F(000) = 824, the final R = 0.0579 and wR = 0.1566 for 2584 observed reflections (I 2σ(I)). Interestingly, a colorless compound 1o undergoes photocyclization upon irradiation of UV light to give the blue isomer diarylethene. Upon irradiation with visible light with wavelength greater than 510 nm, the blue compound can return to its initial colorless state.
文摘Structural genomics (SG) is an international effort that aims at solving three-dimensional shapes of important biological macro-molecules with primary focus on proteins. One of the main bottlenecks in SG is the ability to produce dif-fraction quality crystals for X-ray crystallogra-phy based protein structure determination. SG pipelines allow for certain flexibility in target selection which motivates development of in- silico methods for sequence-based prediction/ assessment of the protein crystallization pro-pensity. We overview existing SG databanks that are used to derive these predictive models and we discuss analytical results concerning protein sequence properties that were discov-ered to correlate with the ability to form crystals. We also contrast and empirically compare mo- dern sequence-based predictors of crystalliza-tion propensity including OB-Score, ParCrys, XtalPred and CRYSTALP2. Our analysis shows that these methods provide useful and compli-mentary predictions. Although their average ac- curacy is similar at around 70%, we show that application of a simple majority-vote based en-semble improves accuracy to almost 74%. The best improvements are achieved by combining XtalPred with CRYSTALP2 while OB-Score and ParCrys methods overlap to a larger extend, although they still complement the other two predictors. We also demonstrate that 90% of the protein chains can be correctly predicted by at least one of these methods, which suggests that more accurate ensembles could be built in the future. We believe that current protein crystalli-zation propensity predictors could provide useful input for the target selection procedures utilized by the SG centers.
基金Supported by the NNSFC(21262015,21162011)Science Funds of the Education Office of Jiangxi Province(GJJ11690,GJJ13577)
文摘A new family of photochromic diarylethene compounds, 1-(2-cyano-l,5-dimethyl- 4-pyrryl)-2-[2-methyl-5-(3-pyridyl)-3-thienyl]perfluorocyclopentene (lo) having an unsymmetrical pyrryl and thienyl substituted hexafluorocyclopentene unit, was synthesized and its structure was determined by X-ray analysis. The crystal belongs to triclinic system, space group PI with a = 8.897(7), b = 10.139(8), c = 12.361(9) A, α = 85.222(7), ρ = 75.439(7), γ = 78.736(8)°, Z = 2, V= 1057.8(14) A3, D,.= 1.468 mg/m3, p = 0.220 mm-1, F(000) = 476, the final R = 0.0608 and wR = 0.1754 for 3199 observed reflections (1 〉20(/)). Interestingly, compound 1 exhibits good photochromic properties with alternate irradiation of UV light and visible light (〉 510 nm) to form two photoisomers in hexane solution and crystal phase.
基金Supported by the Scientific and Technical Personnel Service Enterprise Foundation of State Ministry of Science and Technology (2009GJD10016)The Major Production-Study-Research Foundation of Education Department of Hubei Province (CXY2009A010)the Natural Science Foundation of Hubei Province (2010CDA020)
文摘1-Phenyl-2-acetoxy-2-methyl-propanone, a new a-hydroxy ketone derivative, was synthesized by Friedel-Crafts acylation and characterized by FT-IR, 1H NMR, MS spectra and single-crystal X-ray diffraction measurements. The data are as follows: monoclinic, space group P21/c, Z = 4, C12H1403, Mr = 206.24, a = 8.9430(2), b =15.2680(4), c = 8.2550(2) A, β = 91.9650(5)°, V = 1126.60(5)A^3, Dc = 1.216 g/cm^3, μ(MoKα) = 0.087 mm^-1, F(000) = 440, R = 0.0725 and wR = 0.1379 for 1282 observed reflections with I〉 2σ(I). The structure was solved by direct methods and refined by full-matrix least-squares refinement on F2 methods. The benzene ring in the structure is almost coplanar with the adjacent carbonyl groups and t-carbonyl atom. Meanwhile, the long chain is approximately perpendicular to the plane. X-ray analysis reveals that the crystal structure involves two weak intramolecular C-H…O hydrogen bonds.
基金Financially supported by the National Natural Science Foundation of China(21602123)Scientific Foundation from graduate school of China Three Gorges University(SDYC2016121)
文摘Four cytotoxic oxazolidin-2-one derivatives were prepared from alkynyl alcohol and isocynate with high yields of 83~95%, and their structures were characterized by IR, H-RESI-MS and NMR analysis. Meanwhile, the crystal of (Z)-4-benzylidene-3-ethyl-1-oxa-3-azaspiro[4.4] nonan-2-one (5a) was obtained and determined by X-ray single-crystal diffraction. Crystal data: monoclinic system, space group P121/c1, a = 10.9284(2), b = 9.47510(10), c = 14.2510(2) ?, β = 111.917(2)o, V = 1369.01(3) ?3, Z = 4, F(000) = 552.0, Dc = 1.248 Mg/m3, μ = 0.652 mm-1, R = 0.0473 and wR = 0.1207 for 2699 independent reflections (Rint = 0.0206) and 2581 observed ones (I 〉 2σ(I)).
基金Supported by the National Natural Science Foundation of China(5137307221363009)+3 种基金the Project of Natural Science Foundation of Jiangxi Province(20142BAB203005)the Project of Science Funds of Jiangxi Education Office(KJLD12035GJJ13577)the PhD start-up fund of Jiangxi Science&Technology Normal University
文摘A new photochromic diarylethene, [1-(2-methyl-5-(4-cyanophenyl)-3-thienyl-2- (2-methyl-5-phenyl-3-thienyl)]perfluorocyclopentene (lo, C28H17F6NS2), was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. Its crystal belongs to the monoclinic system, space group P21/c with a = 24.1381(5), b = 9.3834(6), c = 11.1073(8), fl = 94.477(4)°, Z = 4, V= 2508.1(3) A3, Dc = 1.445 mg/m3, μ = 0.275, F(000) = 1112, the final R = 0.0482 and wR = 0.1429 for 5834 observed reflections (I 〉 2σ(I)). Further study demonstrated the diarylethene underwent reversible photochromism, changing between colorless and blue in hexane solution, crystalline phase and PMMA films, respectively.
文摘In the Bi-Sr-Ca-Cu-O superconductor system, two superconducting phases (85K and 105K) were found by Maeda et al. By substituting Pb, enhanced superconducting properties and structure stabilization in these compounds have been reported. Recently, the
基金supported by the Beijing Institute of Technology (No.20060542021)
文摘8,9,12-Trihydro-9,9-pentamethylene- 12-(3-nitrophenyl)- 11H-naphtho[ 1',25,6]- pyrano[2,3-d]pyfimidin- 11 (10H)-one 1, another conversion product of Ffiedlandler reaction, has been synthesized by the reaction of 2-amino-4-(3-nitrophenyl)-4H-benzo[f]chromene-3-carbonitrile 2 with cyclohexanone in the presence of Lewis acid catalysts. The crystal of the title compound 1 THF solvate, C60H62N6O10, was obtained and determined by X-ray diffraction method. The crystal is of triclinic, space group P1 with a = 11.4633(11), b = 12.6247(12), c = 19.658(2)A, α = 72.642(8), β = 89.045(9), γ = 68.340(5)°, V = 2509.6(4), Z = 2, De = 1.359 g/cm^3, F(000) = 1088, Mr = 1027.16, the final R = 0.0674 and wR = 0.1869 with Ⅰ 〉 2σ(Ⅰ) and the goodness-of-fit S = 1.045 on F^2. The pyrimidine ring has an envelope conformation, linked with a six-membered ring through a spiro C atom. The crystal packing of 1 THF solvate is stabilized by N-H…O hydrogen bonds, and π-π stacking interaction occurs between two adjacent nearly planar molecules of 1.
基金Supported by the National Natural Science Foundation of China(21701065)"5511" Science and Technology Innovation Talent Project of Jiangxi Province(20165BCB18015)+2 种基金the Project of Natural Science Foundation of Jiangxi Province(20171ACB20025,20171BAB203011)the Project of the Science Funds of Jiangxi Education Office(GJJ170659)the Project of Jiangxi Advantage Sci-Tech Innovative Team(20142BCB24012)
文摘The crystal structure of fused photochromic diarylethene dimer, 1,4-bis-[4-(4-{2-(5-phenyl)-2-methyl-thiophen-3-yl]-3,3,4,4,5,5-hexafluoro-cyclopent-1-enyl}-5-methyl-thiophen-2-yl) buta-1,3-diyne(1 oo, C46 H23 F12 S4) was determined by single-crystal X-ray diffraction analysis. This crystal belongs to the triclinic system, space group P1 with a = 7.546(3), b = 8.869(3), c = 16.196(5), α = 98.000(4)°, β = 100.803(4)°, γ = 98.449(4)°, Z = 2, V = 1037.6(6) ?~3, Dc = 1.496 mg/m^3, μ = 0.317, F(000) = 474, the final R = 0.0428 and wR = 0.1199 for 4115 observed reflections(I > 2σ(I)). Further study demonstrated this compound underwent reversible photochromism with color-switching between colorlessness and green in crystalline state. Upon 365 nm irradiation, the diarylethene shows one step photochromism to form isomer 1 oc. When irradiated with 312 nm, the stepwise photocyclization reactions occurred in diarylethene dimer through the line of 1 oo to 1 oc to 1 cc.