Site connectivities in sodium aluminoborate glasses: multinuclear and multiple quantum NMR results

In a series of sodium aluminoborate glasses, we have applied triple-quantum magic-angle spinning (3QMAS) 17O NMR to obtain high-resolution information about the connections among various network structural units, to explore the mixing of aluminum and boron species. Oxygen-17 3QMAS spectra reveal changes in connectivities between AlO4 ([4]Al), AlO5 and AlO6 ([5,6]Al), BO3 ([3]B) and BO4 ([4]B) units, by quantifying populations of bridging oxygens such as Al-O-Al, Al-O-B and B-O-B and of non-bridging oxygens. Several linkages such as [4]Al-O-[4]Al and three-coordinated oxygen associated with [5,6]Al in Al-O-Al, [4]Al-O-[4]B, [4]Al-O-[3]B and [5,6]Al-O-[3]B in Al-O-B as well as [4]B-O-[3]B and [3]B-O-[3]B in B-O-B can be distinguished for the first time. The fractions of these linkages were calculated from models of random mixing and of mixing with maximum avoidance of tetrahedral-tetrahedral linkages. The results suggest that the structure of all of glasses in this study is well approximated by the latter model. However, the energetic "penalty" for formation of [4]Al-O-[4]B may be somewhat less than for [4]Al-O-[4]Al and [4]B-O-[4]B. In general, the new results presented here are similar to those obtained on glasses in this system by 27Al{11B} REDOR NMR (J. Phys. Chem. B 104 (2000) 6541), but provide considerably more detail on network connectivity and ordering schemes.     

Inelastic cross-sections and natural lifetimes for the 62D3/2, 5/2 and 82S1/2 states of Rb

The results of an experimental study of population dynamics following excitation of [0pt] and [0pt] states of rubidium are reported. Excitation transfer and quenching cross-sections in collisions with ground state rubidium atoms, and natural lifetimes have been measured. The experiment was performed in a vapour cell, using pulsed two-photon excitation and photon counting detection. The analysis of time dependent signals was based on a rate equation model in which transitions induced by thermal radiation have been accounted for. The measurements yielded following results: (1) [0pt] state J-mixing cross-section: [0pt] ; (2) cross-sections for [0pt] excitation transfer process: [0pt] ; (3) quenching cross-sections: [0pt] , [0pt] , [0pt] ; [0pt](4) radiative lifetimes: [0pt] ns, [0pt] ns, [0pt] ns. Received 1st December 1998 and Received in final form 17 May 1999     

1H and 13C NMR Spectra of Alditolyl Derivatives of 3-Hydrazino-5-Methyl[1,2,4]triazino[5,6-b]indole and Their Cyclized Products.

The ¹H and ¹³C NMR spectra of sugar (5-methyl [1, 2, 4]-triazino [5, 6-b] indol-3-yl) hydrazones (1), per-0-acetyl aldehydo sugar 1-acetyl-1-(5-methyl [1, 2, 4] triazino [5, 6-b]-indol-3-yl) hydrazones (2), l- (penta-0-acetyl-pentitol-1-yl)-10-methyl [l, 2, 4] triazolo [3′, 4′:3, 4] [l, 2, 4] triazino [5, 6-b]-indoles (3) have been investigated. The 2 D NMR (H, C COSY) spectrum of 2a has been studied.     

Band structures and proton-neutron interactions in Ta

Six rotational bands in the odd-odd nucleus ¹⁷⁴Ta have been populated with the ¹⁶⁰Gd(¹⁹F,5n) reaction. High-spin states were identified using the NORDBALL array. Both signatures of the doubly decoupled π1/2⁻ [541] ν1/2⁻ [521] band and semi-decoupled π1/2⁻ [541] ν7/2⁻ [633] band are observed, in addition to the high-K couplings of the π9/2⁻ [514] ν7/2⁺ [633], π9/2⁻ [514] ν5/2⁻ [512], π7/2⁺ [404] ν7/2⁺ [633], and π5/2⁺ [402] ν5/2⁻ [512] configurations. The signature splitting of the π1/2⁻ [541] ν7/2⁺ [633] band is inverted from the expected splitting, and this is interpreted as being due to a residual proton-neutron interaction. It is shown empirically that this interaction, together with deformation changes, can account for the increased crossing frequency associated with the alignment of i_13/2 neutrons in the π1/2⁻ [541] bands of odd-Z nuclei.     

VCVs vs CVCs for stop/fricative distinctions by hearing-impaired and normal-hearing listeners

Moderately to profoundly hearing-impaired (n = 30) and normal-hearing (n = 6) listeners identified [p, k, t, f, theta, s] in [symbol; see text], and [symbol; see text]s tokens extracted from spoken sentences. The [symbol; see text]s were also identified in the sentences. The hearing-impaired group distinguished stop/fricative manner more poorly for [symbol; see text] in sentences than when extracted. Further, the group's performance for extracted [symbol; see text] was poorer than for extracted [symbol; see text] and [symbol; see text]. For the normal-hearing group, consonant identification was similar among the syllable and sentence contexts.     

Generalized susceptibilities and phonon anomalies in Pd and Pt metals

The generalized susceptibility, χ(q), in Pd and Pt for q along the [100], [110], [111], and [120] directions was determined from their APW and RAPW energy band structures, respectively, using the analytic tetrahedron linear energy scheme of Rath and Freeman. The band structures were previously found to yield Fermi surface radii, temperature dependencies of the static magnetic susceptibility, χ(T), resistivity, and a spin lattice relaxation, T₁T, in very good agreement with experiment. In the χ(q) calculations, we used 2048 tetrahedra in 1/48th irreducible BZ and the energy eigenvalues for bands 4, 5, and 6 which cross the Fermi energy as fitted to a Fourier series representation. The intraband parts of χ(q) at q = 0 for both metals are found to agree with the density of states at the Fermi energy to without 0.5%. Our results show that the dominant contribution to χ_intra arises from the dominant band 5 whose “jungle-gym” FS has strong nesting features; the main peak for Pd occurs at the same q value (= 0.65π/a) for q along the [0q0], [q, q, 0], and [q, q, q] directions. The locus of this main peak is a square in the (0, 0, 1) plane. The maximum of χ_intra for q along the [110] and [111] directions are 23% and 13%, respectively, higher than the value of χ(q) at q = 0. For q along the [010] and [120] directions, the peak is, however, lower than the value of χ_intra at q = 0. Hence, while phonon anomalies are predicted for the [110] and [111] directions, no anomaly is predicted for either the [100] or [120] direction. The predicted q value for the [110] anomaly, $\text{q}\text{= 0.65π/a}$ is close to the experimental value of ～0.7 π/a. Although there may be a hint of an anomaly at 0.56 [111] in the measurements, a more detailed investigation of this region is called for. For platinum, χ_intra for q along the [010], [110] and [111] directions has main peaks which occur at q = 0.68 π/a, 0.75 π/a, and 0.85 π/a, respectively. Here too, this main peak comes from the nesting of the jungle-gym Fermi surface which is not, however, as flat as that of palladium. Anomalies are predicted (although weaker in Pt than in Pd) along [110] and [111] but not along [100] and [120]. The [110] anomaly is close to the measured q value (～0.7–0.8 π/a). Also in agreement with experiment, we predict a weaker [110] anomaly for Pt than for Pd. In both Pd and Pt, weaker anomalies are predicted for the [111] direction than for the [110] direction.     

An electron paramagnetic resonance study of the tetragonally distorted [Formula: see text] ion in [Formula: see text] and [Formula: see text

Chromium-doped [Formula: see text] and [Formula: see text] have been studied by both EPR and ENDOR spectroscopy. [Formula: see text] ions enter the fluorite structure in distorted substitution cation sites. In both matrices the distortion observed is tetragonal. X- and Q-band EPR measurements at temperatures between 4 and 300 K allowed us to determine the ion symmetry and the following spin-Hamiltonian parameters: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] for [Formula: see text]; and [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] for [Formula: see text]. For [Formula: see text], the weak superhyperfine interaction of [Formula: see text] with the surrounding [Formula: see text] ions has been studied by both EPR and ENDOR techniques for [Formula: see text]. No ENDOR signals were detected for [Formula: see text]. The results are tentatively explained in terms of a Jahn - Teller effect corresponding to [Formula: see text] coupling strongly stabilized by lattice stresses, although other possible origins for the distortion cannot be completely ruled out.     

Formant onsets and formant transitions as developmental cues to vowel perception

The purpose of this study was to determine whether children give more perceptual weight than do adults to dynamic spectral cues versus static cues. Listeners were 10 children between the ages of 3;8 and 4;1 (mean 3;11) and ten adults between the ages of 23;10 and 32;0 (mean 25;11). Three experimental stimulus conditions were presented, with each containing stimuli of 30 ms duration. The first experimental condition consisted of unchanging formant onset frequencies ranging in value from frequencies for [i] to those for [a], appropriate for a bilabial stop consonant context. The second two experimental conditions consisted of either an [i] or [a] onset frequency with a 25 ms portion of a formant transition whose trajectory was toward one of a series of target frequencies ranging from those for [i] to those for [a]. Results indicated that the children attended differently than the adults on both the [a] and [i] formant onset frequency cue to identify the vowels. The adults gave more equal weight to the [i]-onset and [a]-onset dynamic cues as reflected in category boundaries than the children did. For the [i]-onset condition, children were not as confident compared to adults in vowel perception, as reflected in slope analyses.     

瓜环与咪唑[4,5,f]-1,10-菲咯啉衍生物相互作用模式的测试

以合成的三种的咪唑[4,5,f]-1,10-菲咯啉衍生物为客体,以瓜环(cucurbit[n]uriln=6～8)为主体,利用1H NMR技术,荧光光谱和紫外吸收光谱方法,测试了主客体相互作用形式、形成包结物的结构特征及其光学性质,三种方法得到的结果相同.研究表明,六元瓜环(Q[6])仅能与2-(4-甲基苯基)-咪唑-[4,5,f]菲咯啉(W1)盐酸盐相互作用(包结比为1:1);七元瓜环(Q[7])与三种客体2-(4-甲基苯基)-咪唑-[4,5,f]菲咯啉,2-(2-甲基苯基)-咪唑-[4,5,f]菲咯啉(W2)以及2-(3-甲氧基苯基)-咪唑-[4,5,f]菲咯啉(W3)的盐酸盐均以1:1的物质的量比发生相互作用;而八元瓜环(Q[8])除与W1形成的是1:2的包结物外,与另外两种客体W2,W3也是形成1:1的包结配合物.     

Sigma Terms and Strangeness Contents of Baryon Octet in Modified Chiral Perturbation Theory

[1]J.Gasser,H.Leutwyler,and M.E.Sainio,Phys.Lett.B 253 (1991) 252. [2]John Ellis,Eur.Phys.J.A 24S2 (2005) 3,[arXive:hepph/0411369]. [3]T.Inoue,V.E.Lyubovitskij,Th.Gutsche,and Amand Faessler,Phys.Rev.C 69 (2004) 035207,[arXive:hepph/0311275]. [4]M.M.Pavan,I.I.Strakovsky,R.L.Workman,and R.A.Arndt,PiN Newslett.16 (2002) 110,[arXive:hepph/0111066]. [5]V.E.Lyubovitskij,Th.Gutsche,Amand Faessler,and E.G.Drukarev,Phys.Rev.D 63 (2001) 054026,[arXive:hep-ph/0009341]. [6]S.D.Bass,Phys.Lett.B 329 (1994) 358,[arXive:hepph/9404294]. [7]Marc Knecht,PiN Newslett.15 (1999) 108,[arXive:hepph/9912443]. [8]P.Schweitzer,Phys.Rev.D 69 (2004) 034003. [9]B.C.Lehnhart,J.Gegelia,and S.Scherer,J.Phys.G 31(2005) 89,[arXive:hep-ph/0412092]. [10]P.J.Ellis and K.Torikoshi,Phys.Rev.C 61 (1999)015205. [11]Gerald E.Hite,William B.Kaufmann,and Richard J.Jacob,Phys.Rev.C 71 (2005) 065201. [12]S.Weinberg,Physica A 96 (1979) 327. [13]J.Gasser and H.Leutwyler,Nucl.Phys.B 250 (1985)465. [14]J.Gasser,M.E.Sainio,and A.Svarc,Nucl.Phys.B 307(1988) 779. [15]P.Papazoglou,D.Zschiesche,S.Schramm,J.SchaffnerBielich,H.St(o)cker,and W.Greiner,Phys.Rev.C 59(1999) 411. [16]T.Fuchs and J.Gegelia,Phys.Rev.D 68 (2003) 056005.     

在N2中[VnCr3—n（μ3—O）（μ—O2CCH3）6（THF）3]X[n=0—3,X=Cl^—1,ClO4^—,（VO5）0.5^—]及[VnFe3—n（μ3—O）（μ—O2CCH3）6（THF）3]X（n=0—3,X=Cl^—1）

The reaction behavior of the title complexes have been investigated by means of in situ IR in nitrogen atmosphere. It has been found that they enabled the acetic acid to convert to acetone and methane in different temperatures. The results indicate that the sequence of the ketonization reaction activity for the clusters was [V3OAT] > [VFe2OAT], [V2CrOAT] > [Fe3OAT], [VCr2OAT] > [Cr3OAT] [OAT = (mu 3-O) (mu-O2CCH3)6 (THF)3], and the sequence of the methanation reaction activity for the clusters was [Cr3OAT] > [VCr2OAT], [V2CrOAT] > [V3OAT] > [VFe2OAT], [Fe2OAH]. The ketonization reaction activity of [Fe3OAT] were obviously lower than that of [Fe3OAH] [OAH = (mu 3-O) (mu-O2CCH3)6 (H2O)3] and the methanation reaction activity of [Cr3OAT] were also much lower than that of [Cr3OAH]. The difference between [Fe3OAH], [Cr3OAT] and [Fe3OAH], [Cr3OAH] mentioned above were discussed.     

Global validity of the Boltzmann equation for two- and three-dimensional rare gas in vacuum: Erratum and improved result

We point out an error in our earlier papers [1] and [2] and present a more direct and natural proof which, although based on the same physical ideas of the previous ones, saves and actually improves the validity results for the Boltzmann equation given in [1] and [2].     

Formation and growth mechanism of ripple-like AlN nanowires

Single-crystal ripple-like AlN nanowire with tuned diameter was fabricated through direct reaction aluminum with nitrogen by arc discharge method. The nanowires grow along the [0001] direction and have a radial expansion along the [10[`1]0][10\bar{1}0] direction. The periodic variation of the radial expansion toward [10[`1]0][10\bar{1}0] direction produces the ripple-like AlN nanowires. The growth mechanism of the AlN nanowires is discussed by considering the Al adlayer diffusion on the polar (0001) surface.     

基于六粒子纠缠态和Bell态测量的量子信息分离

通过介绍六粒子纠缠态的新应用研究,提出了一个二粒子任意态的信息分离方案.在这个方案中,发送者Alice、控制者Charlie和接受者Bob共享一个六粒子纠缠态,发送者先执行两次Bell基测量|然后控制者执行一次Bell基测量|最后接受者根据发送者和控制者的测量结果,对自己拥有的粒子做适当的幺正变换,从而能够重建要发送的二粒子任意态.这个信息分离方案是决定性的,即成功概率为100%.与使用相同的量子信道进行二粒子任意态的信息分离方案相比,本文提出的方案只需要进行Bell基测量而不需要执行多粒子的联合测量,从而使得这个方案更简单、更容易,并且在目前的实验室技术条件下是能够实现的.     

Anomalies in the ion transport of phosphoric acid in water and heavy-water environments

This paper presents the experimentally determined precise transport data - (tracer) diffusion coefficients in both water and heavy-water environments, together with molar conductivity and viscosity of (ortho)phosphoric acid in water over an extended concentration range at [Formula: see text]. The concentration (c) dependence of the diffusion coefficients (D), viscosity [Formula: see text] and molar conductivity [Formula: see text] have been analysed. An anomalous depression in the D - [Formula: see text] curve for both [Formula: see text] - [Formula: see text] and [Formula: see text] - [Formula: see text] systems in the neighbourhood of 0.8 M is observed, which is complementary to the sudden sharp rise observed in the [Formula: see text] curve in the neighbourhood of 0.8 M. Although the occurrence of such an anomaly could be inferred from the earlier conductance, e.m.f. and diffusion data, it was never conclusively inferred earlier. This new set of diffusion and viscosity data clearly delineates anomalies in the ion transport of phosphoric acid.     

瓜环[n](n=7,8)与盐酸法舒地尔的相互作用研究

分别以NMR技术、电喷雾质谱、紫外光谱和红外光谱等分析方法考察了瓜环[n](n=7, 8)与盐酸法舒地尔的相互作用. 实验结果显示, 盐酸法舒地尔与两种瓜环都形成了1∶1的包结配合物, 但其主客体配合物的作用模式随着瓜环空腔大小的不同而各不相同. 通过紫外吸收光谱法计算出瓜环[n](n=7, 8)与盐酸法舒地尔的包结常数分别为2 524 L/mol, 1 216 L/mol, 其范围在200 L/mol~10 000 L/mol之内,这说明瓜环对盐酸法舒地尔具有潜在的药物缓释作用.     

Structure Elucidation and Assignment of 1H and 13C Spectra of the New Fused Cyclobutane-Naphthofuran Derivative by Two-Dimensional NMR in Different Solvents

One of the major product from the photodimerization of 2-[2-(2-methyl-phenyl)ethenyl)]naphtho[2. 1-b]furan (1) is a new fused cyclobutane-naphthofuran derivative, 6-(2-methylphenyl)-1-[2-(2-methylphenyl)ethenyl]-7-(2-naphtho-[2,1-b]furyl)-3-[2,1]naphtho-2-oxabicyclo[3.2.0]hept-3-ene (2). Its ¹H and ¹³C NMR spectra were fully assigned by the application of COSY, LR COSY, NOESY, APT and HETCOR experiments in deuterated chloroform, acetone and benzene solutions.     

瓜环与喹啉及其衍生物的相互作用

利用荧光光谱分析方法考察六、七及八元瓜环与喹啉、异喹啉、7-甲基喹啉相互作用的结构特征以及光学特性。与核磁共振技术比较,荧光光谱分析方法具有高灵敏性的特点,不仅可观察到喹啉及其衍生物与七元瓜环相互作用而引起的荧光性质变化;还能观察到它们与六元瓜环或八元瓜环相互作用所产生的变化,这是通常的NMR方法所不能实现的。实验表明喹啉、异喹啉、7-甲基喹啉与六、七及八元瓜环有包结作用,形成多种不同包结比的稳定包结配合物。实验也证实,瓜环与客体之间相互作用受到3种效应的协同影响:(1)疏水性的笼体效应(瓜环以其特殊的疏水性笼状结构,可与多种有机物发生疏水性的笼体作用);(2)亲水性的端口效应(瓜环端口环绕的羰基氧通过离子-偶极相互作用来键合金属离子或有机分子的带电部分);(3)相互作用的客体分子或瓜环笼体空间大小,即尺寸效应。     

A novel protocol for catalyst-free synthesis of fused six-member rings to triazole and pyrazole

Molecular Diversity - Herein, an effectual, quick and novel method is described for the synthesis of new triazolo[1,5-a]pyrimidine, triazolo[5,1-b][1,3] thiazine and pyrazolo[1,5-a]pyrimidine...     

理论研究氧原子与富勒烯C60(Ih)的相互作用

运用密度泛函理论(DFT)方法,研究了异构体C60O[6,6]与C60O[5,6]之间的重排反应机理。结果显示: 它们之间的反应路径是经过一个过渡态没有中间体的一步反应。C60O[6,6] 转化成C60O[5,6]的反应能垒是42.7 kcal*mol-1,在反方向,C60O[5,6]转化成C60O[6,6]的反应能垒是47.3 kcal*mol-1,同时,扫描出氧原子在富勒烯C60(Ih)表面的势能面（PEC）,以详细显示异构体C60O[6,6]与C60O[5,6]之间的重排反应机理。