Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ra...Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.展开更多
We report the detailed crystal structures and physical properties of Ru_(1-x)Mo_(x)alloys in the solid solution range of x=0.1-0.9.Structure characterizations indicate that the crystal structure changes from the hcp-M...We report the detailed crystal structures and physical properties of Ru_(1-x)Mo_(x)alloys in the solid solution range of x=0.1-0.9.Structure characterizations indicate that the crystal structure changes from the hcp-Mg-type,toβ-CrFe-type,and then bcc-W-type.The measurements of physical properties show that the Ru_(1-x)Mo_(x)samples with x≥0.2are superconductors and the superconducting transition temperature T_c as a function of Mo content exhibits a dome-like behavior.展开更多
In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visibl...In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.展开更多
为了利用X射线吸收精细结构(X-ray absorption fine structure,XAFS)谱学技术开展热化学反应动力学研究,在上海光源X射线吸收精细结构谱学线站(BL14W1)开展了时间分辨热化学原位XAFS方法的研究。采用自主研制的数据采集设备解决了时间分...为了利用X射线吸收精细结构(X-ray absorption fine structure,XAFS)谱学技术开展热化学反应动力学研究,在上海光源X射线吸收精细结构谱学线站(BL14W1)开展了时间分辨热化学原位XAFS方法的研究。采用自主研制的数据采集设备解决了时间分辨XAFS技术中不同类型信号同步触发和同步采集的问题,实现了数据间的精准匹配。在单色器转速为720"/s、数据采集设备采样率为2MS/s、数据长度为1200eV的条件下,获得了一个9.6s的Cu标样的数据谱,通过与常规XAFS数据和标准XAFS数据进行对比,结果表明本文得到的时间分辨XAFS实验系统具有良好的准确性、分辨率和信噪比。在此基础上,进一步结合线站自主研制的原位装置开展了时间分辨热化学原位XAFS方法,并利用高温常压原位装置开展了CuO还原为金属Cu的验证性实验。在230℃恒温氢气气氛下30min内观测到Cu吸收边能量逐渐向低能量处偏移,同时它位于8998eV的主峰强度逐渐减弱并且劈裂为双峰结构,出现明显的金属Cu的特征。实验结果表明此方法达到了捕获物质动态演化过程的预期目的,在拓展XAFS谱学实验平台的同时,为热化学反应的动力学过程研究提供了一种强大的实验手段。展开更多
To compare with the predictions of the transitional dynamical symmetry X(5) proposed by Iachello (2001 Phys. Rev. Lett. 87 052502), the critical behaviours of U(5) SU(3) are studied in the space of two control...To compare with the predictions of the transitional dynamical symmetry X(5) proposed by Iachello (2001 Phys. Rev. Lett. 87 052502), the critical behaviours of U(5) SU(3) are studied in the space of two control parameters in the interacting boson model (IBM). A simple-shaped phased diagram has been presented. It is found that X(5) predictions cannot be exactly reproduced by our calculations and that the best agreement is close to the calculations with boson numbers N = 11 and 12. By comparing with experimental data on X(5)-like nuclei, we find that X(5) predictions and IBM calculations can reproduce the energy ratios and E2 transition ones.展开更多
We derive explicit expressions for quantum discord and classical correlation for an X structure density matrix. Based on the characteristics of the expressions, the quantum discord and the classical correlation are ea...We derive explicit expressions for quantum discord and classical correlation for an X structure density matrix. Based on the characteristics of the expressions, the quantum discord and the classical correlation are easily obtained and compared under different initial conditions using a novel analytical method. We explain the relationships among quantum discord, classical correlation, and entanglement, and further find that the quantum discord is not always larger than the entanglement measured by concurrence in a general two-qubit X state. The new method, which is different from previous approaches, has certain guiding significance for analysing quantum discord and classical correlation of a two-qubit X state, such as a mixed state.展开更多
The forms and structures of the phases in Fe-Ni-Co-Nb-Ti-Si low expansion superal-loys have been studied using analytical electron microscopy, high resolution electron microscopy, chemical phase analysis, X-ray diffra...The forms and structures of the phases in Fe-Ni-Co-Nb-Ti-Si low expansion superal-loys have been studied using analytical electron microscopy, high resolution electron microscopy, chemical phase analysis, X-ray diffraction, etc. The effects of yttrium on the microstructures and properties in the superalloys have also been investigated. The results reveal that trace yttrium mainly located in the platelet precipitates makes the crystal structure changed. The platelet precipitates become smaller, denser and rather homogeneous with appropriate yttrium addition. Compared with the conventional low expansion superalloy, the misfit of the platelet phase with the matrix in the yttrium-containing low expansion superalloy decreases from 0.7% to 0.07%, which indicates very low stress at the interface.展开更多
Catalysis has been regarded as an effective strategy to mitigate sluggish reaction kinetics and serious shuttle effect of Li-S batteries.Herein,a spherical structure consists of ultrathin layered Ti_(3)C_(2)T_(x)-TiN ...Catalysis has been regarded as an effective strategy to mitigate sluggish reaction kinetics and serious shuttle effect of Li-S batteries.Herein,a spherical structure consists of ultrathin layered Ti_(3)C_(2)T_(x)-TiN heterostructures(MX-TiN)through in-situ nitridation method is reported.Through controllable nitridation,highly conductive TiN layer grew on the surface and close coupled with interior MXene to form unique 2D heterostructures.The ultrathin heterostructure with only several nanometers in thickness enables outstanding ability to shorten electrons diffusion distance during electrochemical reactions and enlarge active surface with abundant adsorptive and catalytic sites.Moreover,the(001)surface of TiN is dominated by metallic Ti-3d states,which ensures fast transmitting electrons from high conductive MX-TiN matrix and thus guarantees efficient catalytic performance.Calculations and experiments demonstrate that polysulfides are strongly immobilized on MX-TiN,meanwhile the bidirectional reaction kinetics are catalytically enhanced by reducing the conversion barrier between liquid LiPSs and solid Li_(2)S_(2)/Li_(2)S.As a result,the S/MX-TiN cathode achieves excellent long-term cyclability with extremely low-capacity fading rate of 0.022%over 1000 cycles and remarkable areal capacity of 8.27 mAh cm^(−2) at high sulfur loading and lean electrolytes.展开更多
Sentence“bei”(“被”字句)and“bei xx”(被xx)provide syntactic and semantic basis for the generation of the construction“You Bei X Dao(有被x到)”.They are in a continuum and have family similarity.The sentence“bei...Sentence“bei”(“被”字句)and“bei xx”(被xx)provide syntactic and semantic basis for the generation of the construction“You Bei X Dao(有被x到)”.They are in a continuum and have family similarity.The sentence“bei”is a typical member,while“bei xx”is an atypical member.Because the construction“You Bei X Dao”has a single function and less attention,it is at the edge of the continuum and is a marginal member.However,it has certain research value in the inheritance and innovation of“bei”and“bei xx”.展开更多
The title compound stachyose (C24H42021), a biologicaly active tetrasaccharide, was characterized by X-ray diffraction analysis. It crystallizes in the orthorhombic system, space group P21212 with C24H42021, a = 23....The title compound stachyose (C24H42021), a biologicaly active tetrasaccharide, was characterized by X-ray diffraction analysis. It crystallizes in the orthorhombic system, space group P21212 with C24H42021, a = 23.8760(3), b = 12.71028(I2), c = 10.81279(11) A, V = 3281.36(6) A3, Z = 4, Dc= 1.511 g/cm3, Mr = 746.58, F(000) = 1576, and μ = 1.230 mm^-1. The final R = 0.0666 and wR = 0.1797 for 6298 observed reflections (I 〉 2σ(I)). The molecular crystal structure of stachyose shows absolute stereochemistry of fl-D-fructofuranosyl a-D-galactopyranosyl- (1→6)-a-D-galactopyranosyl-(1→6)-a-D-glucopyranoside. The molecule is composed of two a-D-galactoses, one a-D-glucose, and one r-D-fructose and sequentially linked as a-Gal (1 →6) a-Gal (1→6) a-Glc (1→2) fl-Fru. The title compound is stacked into a 3D layer structure through hydrogen bonds. NMR spectra data are also assigned. In the crystal packing, X-ray analysis indicates that there are two intramolecular and eleven intermolecular hydrogen bonds in this compound.展开更多
The synthesis and X-ray crystal structure of a new molecular clip 2 was reported. It (C24H24N4O2, Mr = 400.47) crystallizes in the space group C2/c with a = 15.587(2), b = 8.5805(12), c = 15.259(2) A, β = 102...The synthesis and X-ray crystal structure of a new molecular clip 2 was reported. It (C24H24N4O2, Mr = 400.47) crystallizes in the space group C2/c with a = 15.587(2), b = 8.5805(12), c = 15.259(2) A, β = 102.448(3)°, V= 1992.9 (5)A63, Z = 4, Dc = 1.335 g/cm63,μ = 0.087 mm^-1 and F(000) = 848. It remains monomeric in the crystal and a tape-like structure is formed in the crystal structure of molecular clip. The most unusual structural feature of 2 is the boat conformation of its cyclohexyl ring imposed by the ring fusion at C(9)-C(9a).展开更多
The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires (NWs) passivated with different functional groups (-H, -F and-OH) are investigated by using first-principles calculations. ...The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires (NWs) passivated with different functional groups (-H, -F and-OH) are investigated by using first-principles calculations. The results show that surface passivation influences the characteristics of electronic band structures significantly: the band gap widths and types (direct or indirect) of the Si1-xGe, NWs with different terminators show complex and robust variations, and the effective masses of the electrons in the NWs can be modulated dramatically by the terminators. The study of optical absorption shows that the main peaks of the parallel polarization component of Si1-x Gex NWs passivated with the functional groups exhibit prominent changes both in height and position, and are red-shifted with respect to those of corresponding pure Si NWs, indicating the importance of both the terminators and Ge concentrations. Our results demonstrate that the electronic and optical properties of Si1-xGex NWs can be tuned by utilizing selected functional groups as well as particular Ge concentrations for customizing purposes.展开更多
The title compound 1,5-bis(4-methoxyphenyl)-3-(4-methyl-1,2,3-thiadiazol-5-yl)-pentane-1,5-dione (C22H22N2O4S, Mr=410.49) has been synthesized by the reaction of 4-methyl-1,2,3-thiadiazole-5-carbaldehyde with 4-...The title compound 1,5-bis(4-methoxyphenyl)-3-(4-methyl-1,2,3-thiadiazol-5-yl)-pentane-1,5-dione (C22H22N2O4S, Mr=410.49) has been synthesized by the reaction of 4-methyl-1,2,3-thiadiazole-5-carbaldehyde with 4-methoxyacetophenone, and its structure was characterized by IR, 1H NMR, H RMS, elemental analysis and single-crystal X-ray diffraction. The crystal of the title compound belongs to monoclinic, space group P21/c with a=11.159(3), b=9.002(3), c=20.192(6), β=93.393(5)°, Z=4, V=2024.6(10) 3 , Dc=1.347 g/cm3 , μ=0.191 mm-1 , F(000)=864, R=0.0333 and wR (I〉2σ (I))=0.0840. In this molecule, the 1,2,3-thiadiazol ring is nearly vertical with both phenyl rings, and intermolecular weak hydrogen bonds of C-H…O and C-H…N types together with π-π stacking interactions and interactions between S(1)…N(2) are observed. The above three kinds of interactions extend the molecules into a two-dimensional layer framework. The preliminary biological test showed that the title compound had fungicidal activity.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No.51802025)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No.2020JQ-384)。
文摘Different bilayer structures of HfO_(x)/Ti(TiO_(x)) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy,and the oxygen vacancies are analyzed. Highly improved on/off ratio(~104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfO_(x) sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfO_(x)-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure.
基金Project supported by Beijing Natural Science Foundation (Grant No.Z200005)the National Key R&D Program of China (Grant Nos.2018YFE0202600 and 2022YFA1403800)+1 种基金the National Natural Science Foundation of China (Grant No.12274459)Beijing National Laboratory for Condensed Matter Physics,and Collaborative Research Project of Laboratory for Materials and Structures,Institute of Innovative Research,Tokyo Institute of Technology。
文摘We report the detailed crystal structures and physical properties of Ru_(1-x)Mo_(x)alloys in the solid solution range of x=0.1-0.9.Structure characterizations indicate that the crystal structure changes from the hcp-Mg-type,toβ-CrFe-type,and then bcc-W-type.The measurements of physical properties show that the Ru_(1-x)Mo_(x)samples with x≥0.2are superconductors and the superconducting transition temperature T_c as a function of Mo content exhibits a dome-like behavior.
基金supported by National Natural Science Foundation of China(Nos.62027818,61874034,and 51861135105)Natural Science Foundation of Shanghai(No.18ZR1405000)Shanghai Science and Technology Innovation Program(No.19520711500).
文摘In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.
文摘为了利用X射线吸收精细结构(X-ray absorption fine structure,XAFS)谱学技术开展热化学反应动力学研究,在上海光源X射线吸收精细结构谱学线站(BL14W1)开展了时间分辨热化学原位XAFS方法的研究。采用自主研制的数据采集设备解决了时间分辨XAFS技术中不同类型信号同步触发和同步采集的问题,实现了数据间的精准匹配。在单色器转速为720"/s、数据采集设备采样率为2MS/s、数据长度为1200eV的条件下,获得了一个9.6s的Cu标样的数据谱,通过与常规XAFS数据和标准XAFS数据进行对比,结果表明本文得到的时间分辨XAFS实验系统具有良好的准确性、分辨率和信噪比。在此基础上,进一步结合线站自主研制的原位装置开展了时间分辨热化学原位XAFS方法,并利用高温常压原位装置开展了CuO还原为金属Cu的验证性实验。在230℃恒温氢气气氛下30min内观测到Cu吸收边能量逐渐向低能量处偏移,同时它位于8998eV的主峰强度逐渐减弱并且劈裂为双峰结构,出现明显的金属Cu的特征。实验结果表明此方法达到了捕获物质动态演化过程的预期目的,在拓展XAFS谱学实验平台的同时,为热化学反应的动力学过程研究提供了一种强大的实验手段。
基金Project supported in part by the National Natural Science Foundation of China (Grant Nos 10265001 and 10547003), the Natural Science Foundation of Inner Mongolian, China (Grant No 200607010111), and Chifeng College Scientific Research Fund of China (Grant No ZRZD200604). Acknowledgement The authors are greatly indebted to Professor Long G L for his continuing interest in this work and his many suggestions.
文摘To compare with the predictions of the transitional dynamical symmetry X(5) proposed by Iachello (2001 Phys. Rev. Lett. 87 052502), the critical behaviours of U(5) SU(3) are studied in the space of two control parameters in the interacting boson model (IBM). A simple-shaped phased diagram has been presented. It is found that X(5) predictions cannot be exactly reproduced by our calculations and that the best agreement is close to the calculations with boson numbers N = 11 and 12. By comparing with experimental data on X(5)-like nuclei, we find that X(5) predictions and IBM calculations can reproduce the energy ratios and E2 transition ones.
基金supported by the Natural Science Foundation of Hunan Province of China (Grant No. 09JJ6011)the Natural Science Foundation of Education Department of Hunan Province, China (Grant Nos. 08A055 and 07C528)
文摘We derive explicit expressions for quantum discord and classical correlation for an X structure density matrix. Based on the characteristics of the expressions, the quantum discord and the classical correlation are easily obtained and compared under different initial conditions using a novel analytical method. We explain the relationships among quantum discord, classical correlation, and entanglement, and further find that the quantum discord is not always larger than the entanglement measured by concurrence in a general two-qubit X state. The new method, which is different from previous approaches, has certain guiding significance for analysing quantum discord and classical correlation of a two-qubit X state, such as a mixed state.
基金Chinese foundation of aeronautical science( N o.96 G2 10 0 3)
文摘The forms and structures of the phases in Fe-Ni-Co-Nb-Ti-Si low expansion superal-loys have been studied using analytical electron microscopy, high resolution electron microscopy, chemical phase analysis, X-ray diffraction, etc. The effects of yttrium on the microstructures and properties in the superalloys have also been investigated. The results reveal that trace yttrium mainly located in the platelet precipitates makes the crystal structure changed. The platelet precipitates become smaller, denser and rather homogeneous with appropriate yttrium addition. Compared with the conventional low expansion superalloy, the misfit of the platelet phase with the matrix in the yttrium-containing low expansion superalloy decreases from 0.7% to 0.07%, which indicates very low stress at the interface.
基金supported by the National Natural Science Foundation of China (Grant Nos.52225204, 11974074, and 11804048)the Innovation Program of Shanghai Municipal Education Commission (2021-01-07-00-03-E00109)+3 种基金the Fundamental Research Funds for the Central Universities (2232022G-07 and 2232021D-28)Graduate Student Innovation Fund of Donghua University (CUSF-DH-D-2022007)the Program Innovative Research Team in University (IRT_16R13)the International Joint Laboratory for Advanced fiber and Low- dimension Materials (18520750400).
文摘Catalysis has been regarded as an effective strategy to mitigate sluggish reaction kinetics and serious shuttle effect of Li-S batteries.Herein,a spherical structure consists of ultrathin layered Ti_(3)C_(2)T_(x)-TiN heterostructures(MX-TiN)through in-situ nitridation method is reported.Through controllable nitridation,highly conductive TiN layer grew on the surface and close coupled with interior MXene to form unique 2D heterostructures.The ultrathin heterostructure with only several nanometers in thickness enables outstanding ability to shorten electrons diffusion distance during electrochemical reactions and enlarge active surface with abundant adsorptive and catalytic sites.Moreover,the(001)surface of TiN is dominated by metallic Ti-3d states,which ensures fast transmitting electrons from high conductive MX-TiN matrix and thus guarantees efficient catalytic performance.Calculations and experiments demonstrate that polysulfides are strongly immobilized on MX-TiN,meanwhile the bidirectional reaction kinetics are catalytically enhanced by reducing the conversion barrier between liquid LiPSs and solid Li_(2)S_(2)/Li_(2)S.As a result,the S/MX-TiN cathode achieves excellent long-term cyclability with extremely low-capacity fading rate of 0.022%over 1000 cycles and remarkable areal capacity of 8.27 mAh cm^(−2) at high sulfur loading and lean electrolytes.
基金BLCU supported project for young researchers’program(supported by the Fundamental Research Funds for the Central Universities)(Project No.,22YCX083).
文摘Sentence“bei”(“被”字句)and“bei xx”(被xx)provide syntactic and semantic basis for the generation of the construction“You Bei X Dao(有被x到)”.They are in a continuum and have family similarity.The sentence“bei”is a typical member,while“bei xx”is an atypical member.Because the construction“You Bei X Dao”has a single function and less attention,it is at the edge of the continuum and is a marginal member.However,it has certain research value in the inheritance and innovation of“bei”and“bei xx”.
基金Supported by the public welfare research special project in State Administration for Quality Supervision and Inspection and Quarantine(No.201210209)
文摘The title compound stachyose (C24H42021), a biologicaly active tetrasaccharide, was characterized by X-ray diffraction analysis. It crystallizes in the orthorhombic system, space group P21212 with C24H42021, a = 23.8760(3), b = 12.71028(I2), c = 10.81279(11) A, V = 3281.36(6) A3, Z = 4, Dc= 1.511 g/cm3, Mr = 746.58, F(000) = 1576, and μ = 1.230 mm^-1. The final R = 0.0666 and wR = 0.1797 for 6298 observed reflections (I 〉 2σ(I)). The molecular crystal structure of stachyose shows absolute stereochemistry of fl-D-fructofuranosyl a-D-galactopyranosyl- (1→6)-a-D-galactopyranosyl-(1→6)-a-D-glucopyranoside. The molecule is composed of two a-D-galactoses, one a-D-glucose, and one r-D-fructose and sequentially linked as a-Gal (1 →6) a-Gal (1→6) a-Glc (1→2) fl-Fru. The title compound is stacked into a 3D layer structure through hydrogen bonds. NMR spectra data are also assigned. In the crystal packing, X-ray analysis indicates that there are two intramolecular and eleven intermolecular hydrogen bonds in this compound.
基金the National Natural Science Foundation of China (20672042)
文摘The synthesis and X-ray crystal structure of a new molecular clip 2 was reported. It (C24H24N4O2, Mr = 400.47) crystallizes in the space group C2/c with a = 15.587(2), b = 8.5805(12), c = 15.259(2) A, β = 102.448(3)°, V= 1992.9 (5)A63, Z = 4, Dc = 1.335 g/cm63,μ = 0.087 mm^-1 and F(000) = 848. It remains monomeric in the crystal and a tape-like structure is formed in the crystal structure of molecular clip. The most unusual structural feature of 2 is the boat conformation of its cyclohexyl ring imposed by the ring fusion at C(9)-C(9a).
基金Supported by the National Natural Science Foundation of China under Grant No 11004142the Program for New Century Excellent Talents in University under Grant No 11-035the Project Sponsored by the Scientific Research Foundation for ROCS of the Ministry of Education of China
文摘The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires (NWs) passivated with different functional groups (-H, -F and-OH) are investigated by using first-principles calculations. The results show that surface passivation influences the characteristics of electronic band structures significantly: the band gap widths and types (direct or indirect) of the Si1-xGe, NWs with different terminators show complex and robust variations, and the effective masses of the electrons in the NWs can be modulated dramatically by the terminators. The study of optical absorption shows that the main peaks of the parallel polarization component of Si1-x Gex NWs passivated with the functional groups exhibit prominent changes both in height and position, and are red-shifted with respect to those of corresponding pure Si NWs, indicating the importance of both the terminators and Ge concentrations. Our results demonstrate that the electronic and optical properties of Si1-xGex NWs can be tuned by utilizing selected functional groups as well as particular Ge concentrations for customizing purposes.
基金funded in part by the NNSFC (20872071)the NSF of Tianjin (10JCZDJC17500)+3 种基金the National Key Project for Basic Research(2010CB126105)National Key Technology Research and Development Program (2011BAE06B02 and 2011BAE06B05)the Foundation of Achievements Transformation and Application of Tianjin Agricultural Science and Technology (201002250)Tianjin Key Technology Research and Development Program (11ZCGYNC00100)
文摘The title compound 1,5-bis(4-methoxyphenyl)-3-(4-methyl-1,2,3-thiadiazol-5-yl)-pentane-1,5-dione (C22H22N2O4S, Mr=410.49) has been synthesized by the reaction of 4-methyl-1,2,3-thiadiazole-5-carbaldehyde with 4-methoxyacetophenone, and its structure was characterized by IR, 1H NMR, H RMS, elemental analysis and single-crystal X-ray diffraction. The crystal of the title compound belongs to monoclinic, space group P21/c with a=11.159(3), b=9.002(3), c=20.192(6), β=93.393(5)°, Z=4, V=2024.6(10) 3 , Dc=1.347 g/cm3 , μ=0.191 mm-1 , F(000)=864, R=0.0333 and wR (I〉2σ (I))=0.0840. In this molecule, the 1,2,3-thiadiazol ring is nearly vertical with both phenyl rings, and intermolecular weak hydrogen bonds of C-H…O and C-H…N types together with π-π stacking interactions and interactions between S(1)…N(2) are observed. The above three kinds of interactions extend the molecules into a two-dimensional layer framework. The preliminary biological test showed that the title compound had fungicidal activity.