Recently,Lee et al.claimed the experimental discovery of room-temperature ambient-pressure super-conductivity in a Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037).Remarkably,the claimed superconductivi...Recently,Lee et al.claimed the experimental discovery of room-temperature ambient-pressure super-conductivity in a Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037).Remarkably,the claimed superconductivity can persist up to 400 K at ambient pressure.Despite the experimental im-plication,the electronic structure of LK-99 has not yet been studied.Here,we investigate the electronic structures of LK-99 and its parent compound using first-principles calculations,aiming to elucidate the doping effects of Cu.Our results reveal that the parent compound Pb_(10)(PO_(4))_(6)O is an insulator,while Cu doping induces an insulator-metal transition and thus volume contraction.The band structures of LK-99 around the Fermi level are featured by a half-filled flat band and a fully-occupied flat band.These two very flat bands arise from both the 2p orbitals of 1/4-occupied O atoms and the hybridization of the 3d orbitals of Cu with the 2p orbitals of its nearest-neighboring O atoms.Interestingly,we observe four van Hove singularities on these two flat bands.Furthermore,we show that the flat band structures can be tuned by including electronic correlation effects or by doping different elements.We find that among the considered doping elements(Ni,Cu,Zn,Ag,and Au),both Ni and Zn doping result in the gap opening,whereas Au exhibits doping effects more similar to Cu than Ag.Our work establishes a foundation for fu-ture studies to investigate the role of unique electronic structures of LK-99 in its claimed superconducting properties.展开更多
Three Epimedium species, E. pubescens Maxim., E. sagittatum （Sieb. ＆ Zucc.） Maxim., and E. wushanense T. S. Ying, which are sympatrically distributed in the western Hubei Province, have been used in traditional Chi...Three Epimedium species, E. pubescens Maxim., E. sagittatum （Sieb. ＆ Zucc.） Maxim., and E. wushanense T. S. Ying, which are sympatrically distributed in the western Hubei Province, have been used in traditional Chinese medicine （TCM） for about 2,000 years. Genetic variability and population genetic structure of 11 natural populations of these Epimedium species were investigated using isoelectric focusing in thin-layer polyacrylamide slab gels. Of the 22 enzyme systems prescreened, six coding for 13 loci and 45 alleles were resolved, which were used for analyzing genetic diversity and population structure at both intraspecific and interspecific levels. The results showed that： l） high levels of genetic diversity were observed in all three species （A = 2.6-3.2, P = 69.2%-84.6%, Ho= 0.274-0.377, HE= 0.282-0.369）, which were higher than that of other herbaceous and aulmal-pollinated species with similar life-history characteristics; 2） there was significant deviation from Hardy-Weinberg Equilibrium, with one half of the loci showing heterozygote excess and the other homozygote excess, in all populations, suggesting the complicated breeding system of Epimedium species; 3） the low level of intraspecific and interspecific genetic differentiation （GST= 0.0246-0.0409 and 0.0495-0.1213, respectively） indicated a high level of gene flow among populations and close genetic relationship among the three species; and 4） UPGMA cluster analysis further showed that E. pubescens was more closely related to E. sagittatum than to E. wushanense, which was in good agreement with the morphological characters and the recent phylogenetic analysis of these species. On the basis of these results, it was concluded that the mixed breeding system, long-lived perennial life form, ancient evolutionary history, and seed dispersal by ants in Epimedium are responsible for the genetic variation and population structure of these species.展开更多
The title compound （E）-4-tert-butyl-N-（2,4-dichlorobenzylidene）-5-（1,2,4-triazol-1-yl）-thiazol-2-amine was synthesized by the reaction of 4-tert-butyl-5-（1,2,4-triazol-1-yl）-thiazol-2-amine with 2,4-dichlorobe...The title compound （E）-4-tert-butyl-N-（2,4-dichlorobenzylidene）-5-（1,2,4-triazol-1-yl）-thiazol-2-amine was synthesized by the reaction of 4-tert-butyl-5-（1,2,4-triazol-1-yl）-thiazol-2-amine with 2,4-dichlorobenzaldehyde, and its crystal structure was determined by singlecrystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1 with a = 7.9748（4）, b = 10.1803（5）, c = 11.4603（6）, α = 102.882（1）, β = 100.253（1）, γ = 104.457（1）°, V = 850.95（7）3, Z = 2, F（000） = 392, C16H15Cl2N5S, Mr = 380.29, Dc = 1.484 g/cm3, S = 1.095, μ = 0.512 mm-1, the final R = 0.0301 and wR = 0.0965 for 3334 observed reflections （I 〉 2σ（I））. The preliminary antitumor activity shows that for the title compound the IC50 of Hela is 0.175 μmol/mL and that of Bel7402 is 0.156 μmol/mL.展开更多
The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber rei...The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.展开更多
Comparing with the predictions of the transitional dynamical symmetry E（5） proposed by Iachello [Phys. Rev. Lett. 85 （2000） 3580], the critical behaviors from U（5）-0（6） are studied in the space of two control ...Comparing with the predictions of the transitional dynamical symmetry E（5） proposed by Iachello [Phys. Rev. Lett. 85 （2000） 3580], the critical behaviors from U（5）-0（6） are studied in the space of two control parameters in the interacting boson model. A simple shape phase diagram has been presented. It is found that E（5） predictions cannot be exactly reproduced by our calculations and that the best agreement is close to the calculations with boson number N = 9. By comparing with experimental data on E（5）-like nuclei, we find that E（5） predictions and IBM calculations can reproduce the energy ratios and E2 transition ones.展开更多
This paper compares data from linearized and nonlinear Zebiak-Cane model, as constrained by observed sea surface temperature anomaly （SSTA）, in simulating central Pacific （CP） and eastern Pacific （EP） E1 Nino. T...This paper compares data from linearized and nonlinear Zebiak-Cane model, as constrained by observed sea surface temperature anomaly （SSTA）, in simulating central Pacific （CP） and eastern Pacific （EP） E1 Nino. The difference between the temperature advections （determined by subtracting those of the linearized model from those of the nonlinear model）, referred to here as the nonlinearly induced temperature advection change （NTA）, is analyzed. The results demonstrate that the NTA records warming in the central equatorial Pacific during CP E1 Nino and makes fewer contributions to the structural distinctions of the CP E1 Nino, whereas it records warming in the eastern equatorial Pacific during EP E1 Nino, and thus significantly promotes EP E1 Nino during E1 Nino-type selection. The NTA for CP and EP E1 Nino varies in its amplitude, and is smaller in CP E1 Nino than it is in EP E1 Nino. These results demonstrate that CP E1 Nino are weakly modulated by small intensities of NTA, and may be controlled by weak nonlinearity; whereas, EP E1 Nino are significantly enhanced by large amplitudes of NTA, and are therefore likely to be modulated by relatively strong nonlinearity. These data could explain why CP E1 Nino are weaker than EP E1 Nino. Because the NTA for CP and EP E1 Nino differs in spatial structures and intensities, as well as their roles within different E1 Nino modes, the diversity of E1 Nino may be closely related to changes in the nonlinear characteristics of the tropical Pacific.展开更多
The title compound （E）-2-[（4-tert-butyl-5-（4-methoxybenzyl）thiazol-2-ylimino）methyl]phenol was synthesized by the reaction of 5-（4-methoxybenzyl）-4-tert- butylthiazol-2-amine with salicylaldehyde, and its crys...The title compound （E）-2-[（4-tert-butyl-5-（4-methoxybenzyl）thiazol-2-ylimino）methyl]phenol was synthesized by the reaction of 5-（4-methoxybenzyl）-4-tert- butylthiazol-2-amine with salicylaldehyde, and its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c with a = 5.9362（8）, b = 11.5070（15）, c = 29.460（4）A, β= 97.326（3）°, V = 1995.9（5） A^3, Z = 4, F（000） = 808, C22H24N2O2S, Mr= 380.49, De= 1.266 g/cm^3, S = 1.031,μ = 0.181 mm^-1, the final R = 0.0474 and wR = 0.1441 for 4327 observed reflections （I 〉 2σ（I））. Intramolecular O-H…N hydrogen bond is observed in the crystal. The preliminary bioassay showed that the title compound exhibits 95% inhibition rate against Rhizoctonia solani at the test concentration of 500 mg/L.展开更多
At present,the main detection instruments for observing sporadic E(Es)layers are ground-based radars,dense networks of ground-based global navigation satellite system(GNSS)receivers,and GNSS radio occultation,but they...At present,the main detection instruments for observing sporadic E(Es)layers are ground-based radars,dense networks of ground-based global navigation satellite system(GNSS)receivers,and GNSS radio occultation,but they cannot capture the whole picture of the horizontal structure of Es layers.This study employs the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension model(WACCM-X 2.1)to derive the horizontal structure of the ion convergence region(HSICR)to explore the shapes of the large-scale Es layers over East Asia for the period from June 1 to August 31,2008.The simulation produced the various shapes of the HSICRs elongated in the northwest-southeast,northeast-southwest,or composed of individual small patches.The close connection between Es layer critical frequency(foEs)and vertical ion convergence indicates that the HSICR is a good candidate for revealing and explaining the horizontal structure of the large-scale Es layers.展开更多
The title compound 2 (C15H22NO4PS, Mr = 343.38) was prepared by the reaction of α-benzoylthioformmorpholine 1 with trimethyl phosphite. The crystal is of monoclinic, space group P21/c with a = 14.906(2), b = ...The title compound 2 (C15H22NO4PS, Mr = 343.38) was prepared by the reaction of α-benzoylthioformmorpholine 1 with trimethyl phosphite. The crystal is of monoclinic, space group P21/c with a = 14.906(2), b = 8.4711(12), c = 13.343(2) ?, β = 96.761(4)o, Z = 4, V = 1673.1(5) ?3, Dc = 1.363 g/cm3, μ(MoKα) = 3.06 cm-1, F(000) = 728, the final R = 0.0590 and wR = 0.1740 for 3036 observed reflections (I > 2σ(I)). X-ray analysis revealed that the interatomic distance of C(5)–C(6) is 1.353(4) ?, indicating it is a normal C=C double bond. The P(1) atom takes a distorted tetrahedral geometry, and the morpholine ring adopts a chair conformation. The morpholino group is located at the 1-position of vinylphosphonate, and the phenyl and thiomethyl groups at the 2-position.展开更多
A new asymmetric bidentate copper（Ⅱ） complex,CuL 2（HL=2-（（E）-（4-bromophenylimino）methyl）-6-bromo-4-chlorophenol）,has been synthesized and characterized by elemental analyses and single-crystal X-ray diffrac...A new asymmetric bidentate copper（Ⅱ） complex,CuL 2（HL=2-（（E）-（4-bromophenylimino）methyl）-6-bromo-4-chlorophenol）,has been synthesized and characterized by elemental analyses and single-crystal X-ray diffraction.The complex crystallizes in the monoclinic space group P2 1 /c with a=11.218（3）,b=9.355（3）,c=13.449（4）,β=108.722（4）°,V=1336.8（6）3,Z=2,Dc=2.008 g/cm 3,μ（MoKα）=7.024 mm-1,F（000）=806,S=0.999,the final R=0.0342 and wR=0.0641for2611observed reflections （I〉2σ（I））.The central copper（Ⅱ） is four-coordinate and bonds to two nitrogen and two oxygen atoms from two Schiff base ligands.The complex is linked into a two-dimensional supramolecular structure by weak intermolecular interactions.In addition,DNA-binding properties of the metal complex were investigated using spectrometric titrations and viscosity measurements.The results show that the complex binds with calf-thymus DNA（CT-DNA）,presumably via a partial intercalative mode.The intrinsic binding constant of the Cu（Ⅱ） complex with DNA is 7.335×10 3 M-1.展开更多
Protein Secondary Structure Prediction (PSSP) is considered as one of the major challenging tasks in bioinformatics, so many solutions have been proposed to solve that problem via trying to achieve more accurate predi...Protein Secondary Structure Prediction (PSSP) is considered as one of the major challenging tasks in bioinformatics, so many solutions have been proposed to solve that problem via trying to achieve more accurate prediction results. The goal of this paper is to develop and implement an intelligent based system to predict secondary structure of a protein from its primary amino acid sequence by using five models of Neural Network (NN). These models are Feed Forward Neural Network (FNN), Learning Vector Quantization (LVQ), Probabilistic Neural Network (PNN), Convolutional Neural Network (CNN), and CNN Fine Tuning for PSSP. To evaluate our approaches two datasets have been used. The first one contains 114 protein samples, and the second one contains 1845 protein samples.展开更多
This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests ...This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests of axial compression were carried.Analysis result and test result fit well.In order to be used in the project,this kind of structure cut-out repairing was calculated.The method presented in this paper has been proved and can be used to solve complicated engineering problems.According to calculations and experimental results combined with application,a principle of choosing wound structure is obtained and principle could be applied to engineering.展开更多
Two potential chiral auxiliaries, N (E ) enoyl(-) bornane 10,2 sultams, were synthesized from (-) bornane 10,2 sultams. The molecular crystal structures of the title compounds were determined by diffraction...Two potential chiral auxiliaries, N (E ) enoyl(-) bornane 10,2 sultams, were synthesized from (-) bornane 10,2 sultams. The molecular crystal structures of the title compounds were determined by diffraction analysis. The crystal of C 16 O 3SNH 25 belongs to a rhombic system, the space group is P 2 12 12 1 with cell parameters: a =0 734 6(7) nm, b =1 142 7(3) nm, c =2 009 7(3) nm, β =90 00°, V =1 686 9 nm 3, Z=4, D c=1 250 g/cm 3, μ =1 926 cm -1 and F (000)=672. The crystal of C 15 O 3SNH 23 belongs to a rhombic system, the space group is P 2 12 12 1 with cell parameters: a =0 738 2(2) nm, b =0 921 6(1) nm, c =2 280 9(8) nm, β =90 00°, V =1 551 7 nm 3, Z =4, D c=1 273 g/cm 3, μ =2 504 cm -1 and F (000)=640. The structural characteristics with respect to the potential utility for the stereoselective Michael addition reaction of the N enoyl group are discussed.展开更多
文摘Recently,Lee et al.claimed the experimental discovery of room-temperature ambient-pressure super-conductivity in a Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037).Remarkably,the claimed superconductivity can persist up to 400 K at ambient pressure.Despite the experimental im-plication,the electronic structure of LK-99 has not yet been studied.Here,we investigate the electronic structures of LK-99 and its parent compound using first-principles calculations,aiming to elucidate the doping effects of Cu.Our results reveal that the parent compound Pb_(10)(PO_(4))_(6)O is an insulator,while Cu doping induces an insulator-metal transition and thus volume contraction.The band structures of LK-99 around the Fermi level are featured by a half-filled flat band and a fully-occupied flat band.These two very flat bands arise from both the 2p orbitals of 1/4-occupied O atoms and the hybridization of the 3d orbitals of Cu with the 2p orbitals of its nearest-neighboring O atoms.Interestingly,we observe four van Hove singularities on these two flat bands.Furthermore,we show that the flat band structures can be tuned by including electronic correlation effects or by doping different elements.We find that among the considered doping elements(Ni,Cu,Zn,Ag,and Au),both Ni and Zn doping result in the gap opening,whereas Au exhibits doping effects more similar to Cu than Ag.Our work establishes a foundation for fu-ture studies to investigate the role of unique electronic structures of LK-99 in its claimed superconducting properties.
基金This work was supported by the National Natural Science Foundation of China (No. 30570171), 100 Talents Program of Chinese Academy of Sciences (No. 05045112), and Wuhan Chenguang Project (No. 20055003059-45).
文摘Three Epimedium species, E. pubescens Maxim., E. sagittatum （Sieb. ＆ Zucc.） Maxim., and E. wushanense T. S. Ying, which are sympatrically distributed in the western Hubei Province, have been used in traditional Chinese medicine （TCM） for about 2,000 years. Genetic variability and population genetic structure of 11 natural populations of these Epimedium species were investigated using isoelectric focusing in thin-layer polyacrylamide slab gels. Of the 22 enzyme systems prescreened, six coding for 13 loci and 45 alleles were resolved, which were used for analyzing genetic diversity and population structure at both intraspecific and interspecific levels. The results showed that： l） high levels of genetic diversity were observed in all three species （A = 2.6-3.2, P = 69.2%-84.6%, Ho= 0.274-0.377, HE= 0.282-0.369）, which were higher than that of other herbaceous and aulmal-pollinated species with similar life-history characteristics; 2） there was significant deviation from Hardy-Weinberg Equilibrium, with one half of the loci showing heterozygote excess and the other homozygote excess, in all populations, suggesting the complicated breeding system of Epimedium species; 3） the low level of intraspecific and interspecific genetic differentiation （GST= 0.0246-0.0409 and 0.0495-0.1213, respectively） indicated a high level of gene flow among populations and close genetic relationship among the three species; and 4） UPGMA cluster analysis further showed that E. pubescens was more closely related to E. sagittatum than to E. wushanense, which was in good agreement with the morphological characters and the recent phylogenetic analysis of these species. On the basis of these results, it was concluded that the mixed breeding system, long-lived perennial life form, ancient evolutionary history, and seed dispersal by ants in Epimedium are responsible for the genetic variation and population structure of these species.
基金Supported by the Natural Science Foundation of Hunan Province (No. 07JJ302)
文摘The title compound （E）-4-tert-butyl-N-（2,4-dichlorobenzylidene）-5-（1,2,4-triazol-1-yl）-thiazol-2-amine was synthesized by the reaction of 4-tert-butyl-5-（1,2,4-triazol-1-yl）-thiazol-2-amine with 2,4-dichlorobenzaldehyde, and its crystal structure was determined by singlecrystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1 with a = 7.9748（4）, b = 10.1803（5）, c = 11.4603（6）, α = 102.882（1）, β = 100.253（1）, γ = 104.457（1）°, V = 850.95（7）3, Z = 2, F（000） = 392, C16H15Cl2N5S, Mr = 380.29, Dc = 1.484 g/cm3, S = 1.095, μ = 0.512 mm-1, the final R = 0.0301 and wR = 0.0965 for 3334 observed reflections （I 〉 2σ（I））. The preliminary antitumor activity shows that for the title compound the IC50 of Hela is 0.175 μmol/mL and that of Bel7402 is 0.156 μmol/mL.
基金the National Seienee Foundation through grants NSF#CMS-9908293 and NSF INT-9904493the Federal Highway Administration and the South Carolina Department of TransPortation(projeet Number 614)
文摘The capability of embedded piezoelectric wafer active sensors(PWAS)to perform in-situ nondestructive evaluation(NDE)for structural health monitoring(SHM)of reinforced concrete(RC)structures strengthened with fiber reinforced polymer(FRP)composite overlays is explored.First,the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer.It was found that the presence of a disbond crack drastically changes the electromecfianical(E/M)impedance spectrum lneasurcd at the PWAS terlninals.The spectral changes depend on the distance between the PWAS and the crack tip.Second,large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer(CFRP)composite overlay.The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles.During these fatigue tests,the CFRP overlay experienced disbonding beginning at about 500,000 cycles.The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection.Good correlation between the PWAS readings and the position and extent of disbond damage was observed.These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.
基金The project supported in part by National Natural Science Foundation of China under Grant Nos. 10265001 and 10547003, the Natural Science Foundation of Inner Mongolian under Grant No. 200607010111, and the Key Scientific Research Fund of Educational Bureau of Inner Mongolian under Grant No. NJ05007 .Acknowledgments The authors are greatly indebted to Prof. G.L. Long for his continuing interest in this work and his many suggestions.
文摘Comparing with the predictions of the transitional dynamical symmetry E（5） proposed by Iachello [Phys. Rev. Lett. 85 （2000） 3580], the critical behaviors from U（5）-0（6） are studied in the space of two control parameters in the interacting boson model. A simple shape phase diagram has been presented. It is found that E（5） predictions cannot be exactly reproduced by our calculations and that the best agreement is close to the calculations with boson number N = 9. By comparing with experimental data on E（5）-like nuclei, we find that E（5） predictions and IBM calculations can reproduce the energy ratios and E2 transition ones.
文摘This paper compares data from linearized and nonlinear Zebiak-Cane model, as constrained by observed sea surface temperature anomaly （SSTA）, in simulating central Pacific （CP） and eastern Pacific （EP） E1 Nino. The difference between the temperature advections （determined by subtracting those of the linearized model from those of the nonlinear model）, referred to here as the nonlinearly induced temperature advection change （NTA）, is analyzed. The results demonstrate that the NTA records warming in the central equatorial Pacific during CP E1 Nino and makes fewer contributions to the structural distinctions of the CP E1 Nino, whereas it records warming in the eastern equatorial Pacific during EP E1 Nino, and thus significantly promotes EP E1 Nino during E1 Nino-type selection. The NTA for CP and EP E1 Nino varies in its amplitude, and is smaller in CP E1 Nino than it is in EP E1 Nino. These results demonstrate that CP E1 Nino are weakly modulated by small intensities of NTA, and may be controlled by weak nonlinearity; whereas, EP E1 Nino are significantly enhanced by large amplitudes of NTA, and are therefore likely to be modulated by relatively strong nonlinearity. These data could explain why CP E1 Nino are weaker than EP E1 Nino. Because the NTA for CP and EP E1 Nino differs in spatial structures and intensities, as well as their roles within different E1 Nino modes, the diversity of E1 Nino may be closely related to changes in the nonlinear characteristics of the tropical Pacific.
基金the National Project of Scientific and Technical Supporting Programs and Ministry of Science & Technology of China (No.2006BAE01A01-4)
文摘The title compound （E）-2-[（4-tert-butyl-5-（4-methoxybenzyl）thiazol-2-ylimino）methyl]phenol was synthesized by the reaction of 5-（4-methoxybenzyl）-4-tert- butylthiazol-2-amine with salicylaldehyde, and its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c with a = 5.9362（8）, b = 11.5070（15）, c = 29.460（4）A, β= 97.326（3）°, V = 1995.9（5） A^3, Z = 4, F（000） = 808, C22H24N2O2S, Mr= 380.49, De= 1.266 g/cm^3, S = 1.031,μ = 0.181 mm^-1, the final R = 0.0474 and wR = 0.1441 for 4327 observed reflections （I 〉 2σ（I））. Intramolecular O-H…N hydrogen bond is observed in the crystal. The preliminary bioassay showed that the title compound exhibits 95% inhibition rate against Rhizoctonia solani at the test concentration of 500 mg/L.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA17010207)scholarship received from the China Scholarship Council (CSC) under grant CSC No.202006410017supported by the Fundamental Research Funds for National University,China University of Geosciences (Wuhan)
文摘At present,the main detection instruments for observing sporadic E(Es)layers are ground-based radars,dense networks of ground-based global navigation satellite system(GNSS)receivers,and GNSS radio occultation,but they cannot capture the whole picture of the horizontal structure of Es layers.This study employs the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension model(WACCM-X 2.1)to derive the horizontal structure of the ion convergence region(HSICR)to explore the shapes of the large-scale Es layers over East Asia for the period from June 1 to August 31,2008.The simulation produced the various shapes of the HSICRs elongated in the northwest-southeast,northeast-southwest,or composed of individual small patches.The close connection between Es layer critical frequency(foEs)and vertical ion convergence indicates that the HSICR is a good candidate for revealing and explaining the horizontal structure of the large-scale Es layers.
基金The project was supported by the Key Laboratory of Organic Synthesis of Jiangsu Province (JSK016)
文摘The title compound 2 (C15H22NO4PS, Mr = 343.38) was prepared by the reaction of α-benzoylthioformmorpholine 1 with trimethyl phosphite. The crystal is of monoclinic, space group P21/c with a = 14.906(2), b = 8.4711(12), c = 13.343(2) ?, β = 96.761(4)o, Z = 4, V = 1673.1(5) ?3, Dc = 1.363 g/cm3, μ(MoKα) = 3.06 cm-1, F(000) = 728, the final R = 0.0590 and wR = 0.1740 for 3036 observed reflections (I > 2σ(I)). X-ray analysis revealed that the interatomic distance of C(5)–C(6) is 1.353(4) ?, indicating it is a normal C=C double bond. The P(1) atom takes a distorted tetrahedral geometry, and the morpholine ring adopts a chair conformation. The morpholino group is located at the 1-position of vinylphosphonate, and the phenyl and thiomethyl groups at the 2-position.
文摘A new asymmetric bidentate copper（Ⅱ） complex,CuL 2（HL=2-（（E）-（4-bromophenylimino）methyl）-6-bromo-4-chlorophenol）,has been synthesized and characterized by elemental analyses and single-crystal X-ray diffraction.The complex crystallizes in the monoclinic space group P2 1 /c with a=11.218（3）,b=9.355（3）,c=13.449（4）,β=108.722（4）°,V=1336.8（6）3,Z=2,Dc=2.008 g/cm 3,μ（MoKα）=7.024 mm-1,F（000）=806,S=0.999,the final R=0.0342 and wR=0.0641for2611observed reflections （I〉2σ（I））.The central copper（Ⅱ） is four-coordinate and bonds to two nitrogen and two oxygen atoms from two Schiff base ligands.The complex is linked into a two-dimensional supramolecular structure by weak intermolecular interactions.In addition,DNA-binding properties of the metal complex were investigated using spectrometric titrations and viscosity measurements.The results show that the complex binds with calf-thymus DNA（CT-DNA）,presumably via a partial intercalative mode.The intrinsic binding constant of the Cu（Ⅱ） complex with DNA is 7.335×10 3 M-1.
文摘Protein Secondary Structure Prediction (PSSP) is considered as one of the major challenging tasks in bioinformatics, so many solutions have been proposed to solve that problem via trying to achieve more accurate prediction results. The goal of this paper is to develop and implement an intelligent based system to predict secondary structure of a protein from its primary amino acid sequence by using five models of Neural Network (NN). These models are Feed Forward Neural Network (FNN), Learning Vector Quantization (LVQ), Probabilistic Neural Network (PNN), Convolutional Neural Network (CNN), and CNN Fine Tuning for PSSP. To evaluate our approaches two datasets have been used. The first one contains 114 protein samples, and the second one contains 1845 protein samples.
文摘This paper calculated load-carrying of isogrid and orthogrid of carbon-epoxy composite trellis wound structure(C/E CTWS) using non-linear finite element method.Based on the analysis,test cases were designed and tests of axial compression were carried.Analysis result and test result fit well.In order to be used in the project,this kind of structure cut-out repairing was calculated.The method presented in this paper has been proved and can be used to solve complicated engineering problems.According to calculations and experimental results combined with application,a principle of choosing wound structure is obtained and principle could be applied to engineering.
文摘Two potential chiral auxiliaries, N (E ) enoyl(-) bornane 10,2 sultams, were synthesized from (-) bornane 10,2 sultams. The molecular crystal structures of the title compounds were determined by diffraction analysis. The crystal of C 16 O 3SNH 25 belongs to a rhombic system, the space group is P 2 12 12 1 with cell parameters: a =0 734 6(7) nm, b =1 142 7(3) nm, c =2 009 7(3) nm, β =90 00°, V =1 686 9 nm 3, Z=4, D c=1 250 g/cm 3, μ =1 926 cm -1 and F (000)=672. The crystal of C 15 O 3SNH 23 belongs to a rhombic system, the space group is P 2 12 12 1 with cell parameters: a =0 738 2(2) nm, b =0 921 6(1) nm, c =2 280 9(8) nm, β =90 00°, V =1 551 7 nm 3, Z =4, D c=1 273 g/cm 3, μ =2 504 cm -1 and F (000)=640. The structural characteristics with respect to the potential utility for the stereoselective Michael addition reaction of the N enoyl group are discussed.
