C,igahertz longitudinal acoustic phonons originating from ultrafast ligand field transitions in hematite thin films

The creation and propagation of longitudinal acoustic phonons （LAPs） in high quality hematite thin films （α-Fe203） epitaxially grown on different substrates （BaTiO3, SrTiO3, and LaAlO3） are investigated using the femtosecond pump- probe technique. Transient reflection measurements （AR/R） indicate the photo-excited electron dynamics, and the initial decay less than 1 ps and the slow decay of -500 ps are attributed to the electron-LO phonon coupling and electron-hole nonradiative recombination, respectively. LAPs in α-Fe2O3 film can be created by ultrafast excitation of the ligand field state, such as the ligand field transitions under 800-nm excitation as well as the ligand to metal charge-transfer with 400- nm excitation. The strain modulations of the sound velocity and the out-of-plane elastic properties are demonstrated in α-Fe2O3 film on different substrates.     

Probing Planckian physics in de Sitter space with quantum correlations

We study the quantum correlation and quantum communication channel of both free scalar and fermionic fields in de Sitter space, while the Planckian modification presented by the choice of a particular α$\alpha$-vacuum has been considered. We show the occurrence of degradation of quantum entanglement between field modes for an inertial observer in curved space, due to the radiation associated with its cosmological horizon. Comparing with standard Bunch–Davies choice, the possible Planckian physics causes some extra decrement on the quantum correlation, which may provide the means to detect quantum gravitational effects via quantum information methodology in future. Beyond single-mode approximation, we construct proper Unruh modes admitting general α$\alpha$-vacua, and find a convergent feature of both bosonic and fermionic entanglements. In particular, we show that the convergent points of fermionic entanglement negativity are dependent on the choice of α$\alpha$. Moreover, an one-to-one correspondence between convergent points H_c$H_c$ of negativity and zeros of quantum capacity of quantum channels in de Sitter space has been proved.     

Cr,Mo,Ni在α-Fe(C)中占位、键合性质及合金化效应的第一性原理研究

基于密度泛函理论第一性原理方法,采用广义梯度近似下的PW91泛函形式,计算了合金元素Cr,Mo,Ni固溶于α-Fe(C)的电子结构,从晶格畸变、结合能、态密度、重叠布居及差分电荷密度等计算结果出发探讨了合金元素在α-Fe(C)中占位、键合性质及其合金化效应,结果表明:Cr优先占据铁素体晶胞顶角位置,而Mo,Ni优先占据体心位置;Cr与晶胞的结合能最大,晶胞最稳定,Ni次之,Mo最低;Cr,Mo,Ni在晶胞中都存在金属键、共价键和微弱离子键的共同作用,成键轨道主要是Cr3d与Fe3d,Mo4d与Fe3d,Ni3d与Fe3d,C2p的交互作用形成的;Cr与晶胞原子间的键合作用强,晶胞的稳定性好,对增强钢材的机械性能帮助较大,Ni的键合作用较弱,但还是能保持晶胞的稳定性,Mo虽然键合作用强,但反键作用也非常强,使晶胞的稳定性大大降低,对钢材的机械性能危害较大.     

Existence and data dependence of fixed points for multivalued operators on gauge spaces

The purpose of this note is to present some fixed point and data dependence theorems in complete gauge spaces and in hyperconvex metric spaces for the so-called Meir-Keeler multivalued operators and admissible multivalued aα-contractions. Our results extend and generalize several theorems of Espínola and Kirk [R. Espínola, W.A. Kirk, Set-valued contractions and fixed points, Nonlinear Anal. 54 (2003) 485-494] and Rus, Petru?el, and Sînt?m?rian [I.A. Rus, A. Petru?el, A. Sînt?m?rian, Data dependence of the fixed point set of some multivalued weakly Picard operators, Nonlinear Anal. 52 (2003) 1947-1959].     

Spherical mean solutions of stochastic wave equation

The paper is concerned with solutions of a multi–dimensional wave equation perturbed by a spatially dependent white noise. A spherical mean representation of the solutions is given. Based on such a representation, the regularity properties of the classical and generalized solutions are

studied.The dependence of the solution regularity on the smoothness of the noise and the spatial dimension is determined.     

An improved synthesis of pennogenin

An improved synthesis of pennogenin, a bioactive component of Chinese herb “Chonglou” (Paris), is described. A ring-switching process opened the ring E of diosgenin and allowed the use of a hydroxyl-directed diboration/oxidation to introduce C17α-OH, hence eliminating the use of OsO₄. This strategy might be rendered to synthesize similar steroids with C17α-OH.     

Structure elucidation and NMR assignments of a new 6,9-cyclotetrahydrofuranlignan from Syringa pinnatifolia

A new 6,9-cyclotetrahydrofuranlignan, 3,3′-dimethoxy-4,4′-dihydroxy-8β,9β,8′α-6,9-cyclotetrahydrofuranlignan, was isolated from the stem of Syringa pinnatifolia Hems1.var. alashanensis MA. et S. Q. ZHOU. Its structures were elucidated on the basis of spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR.     

The Rhodium(II) Carbenoid Cyclization-Cycloaddition Cascade of alpha-Diazo Dihydroindolinones for the Synthesis of Novel Azapolycyclic Ring Systems

Tandem carbonyl ylide formation-1,3-dipolar cycloaddition of α-diazo N-acetyl-tetrahydro-β-carbolin-1-one derivatives occur efficiently in the presence of a dirhodium catalyst to afford bimolecular cycloadducts in high yield. The Rh(II)-catalyzed reaction also takes place intramolecularly to give products derived from trapping of the carbonyl ylide dipole with a tethered alkene. The power of the intramolecular cascade sequence is that it rapidly assembles a pentacyclic ring system containing three new stereocenters and two adjacent quaternary centers stereospecifically in a single step and in high yield.     

Seven-membered ring boronates at trans-diol moieties of carbohydrates

MS and ¹H, ¹³C and ¹¹B NMR results are presented revealing the formation of cyclic seven-membered boronate structures at trans-1,2-diol moieties of carbohydrates providing new opportunities for the activation, protection and analysis of glucopyranose-based oligomers and polymers such as cellulose or starch. ‘Coordination-induced shifts’ in ¹³C NMR spectra were identified for the esterification by boronic acids of carbohydrates, which can be applied for further studies.     

盐酸催化合成α-萘乙酸甲酯

以α-萘乙酸、甲醇为原料,以浓盐酸为催化剂,通过酯化反应合成了植物生长调节剂萘乙酸甲酯。通过正交设计讨论了醇酸摩尔比、催化剂用量、反应时间等因素对酯化产率的影响。在α-萘乙酸50mmol,n(甲醇)：n(α-萘乙酸)=25,催化剂用量为α-萘乙酸质量的17％,反应时间2．0h,酯化温度65℃～69℃的最佳反应工艺条件下,产率97．4％。