Cycloaddition of 2′-azidoethyl glycosides to fullerene[C60] under ultrasonic irradiation

The reactions of fullerene[C₆₀] with 2′-azidoethyl 2,3,4,6-tetra-O-acetyl-α-d-mannopyranoside (2a) and 2′-azidoethyl 2,3,4,6-tetra-O-acetyl-β-d-galactopyranoside (2b) under ultrasonic irradiation cause the cycloaddition of 2′-azidoethyl glycosides to fullerene[C₆₀] and lead to d-glycosyl fullerene[C₆₀] derivatives 3a and 3b, respectively. The glycosyl fullerene[C₆₀] derivatives were characterized by ¹H and ¹³C NMR, UV–vis, FAB-MS, FT-IR spectra and were a 1:1 glycoside fullerene [C₆₀]-adduct.     

Matrix elements for the representations of SO(n) and SO0(n, 1)

Matrix elements of the unitary irreducible representations of the group SO(n) of class higher then 1 (with respect to SO(n−1)) in Gel'fand-Zetlin basis are obtained in explicit form. They are represented as polynomials in cosθ and sinθ of the order equal to the first coordinate of the highest weight. Making use of them the representation matrix elements for the group SO₀(n, 1) in SO(n) basis are calculated.     

α(Q) corrections to particle multiplicity ratios in gluon and quark jets

The order α(Q²) correction to the particle multiplicity ratio in gluon and quark jets is calculated in QCD. Through α(Q²) we find , with r = <n>_{gluon jet}/<n>_{quark jet}. This ratio is independent of the opening angle chosen to define the jets.     

Reduction of hysteresis loss and large magnetocaloric effects in substituted compounds of itinerant-electron metamagnets La(FexSi1−x)13

The maximum value of hysteresis loss E_h^MAX due to the itinerant-electron metamagnetic (IEM) transition of La(Fe_xSi_1−x)₁₃ and the partially substituted compounds La_1−zCe_z(Fe_0.86Si_0.14)₁₃ and La_1−z′Pr_z′(Fe_0.86Si_0.14)₁₃ increases when the magnetocaloric effects (MCEs) become large. It should be noted that the reduction of E_h^MAX without the decrease of large MCEs is achieved in La_1−zCe_z(Fe_0.86Si_0.14)₁₃ and La_1−z′Pr_z′(Fe_0.86Si_0.14)₁₃. For both the compound systems mentioned above, the critical temperature T₀ for the IEM transition decreases and the difference between T₀ and the Curie temperature T_C becomes larger with decreasing T_C. These results are consistent with the magnetic phase diagram of La(Fe_0.86Si_0.14)₁₃ under hydrostatic pressure. Consequently, the reduction of E_h^MAX in La_1−zCe_z(Fe_0.86Si_0.14)₁₃ and La_1−z′Pr_z′(Fe_0.86Si_0.14)₁₃ is closely related with the magnetovolume effects.     

Analysis of irreducible representations of the group U (4) Up(2) × Un(2)

The general method of projection operators is used to construct the noncanonical nonorthogonal basis of arbitrary irreducible representation of the group U (4) in the reduction U (4) U_p(2) × U_n(2), where U_p(2)(U_n(2)) is the transformation group in the proton (neutron) spin space. The completeness of this basis is proved and the matrices of the U (4) group generators and of the Bargmann-Moshinsky operator Ω in this basis are obtained. The matrix Ω exhibits a nondegenerate spectrum of the eigenvalues which may be used as the missing quantum number.     

Correlator of the quark scalar currents and Γtot(H → hadrons) at O(αs) in pQCD

We present the results of the analytical evaluation of the massless four-loop

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(α³_s) correction to the correlator of the quark scalar currents and the Higgs decay rate into hadrons. In numerical form we found (in

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scheme) that Γ (H →

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b ) = (3G_F/4

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π) M_Hm²_b (M_H) [1 + 5.667α_s/π + (35.94 − 1.359n_f) (α_s/π)² + (164.139 − 25.771n_f + 0.259n²_f) (α_s/π)³] where n_f is the number of quark flavour and α_s = α_s(M_H).     

Action of monoatomic cations on the structure and spectra of Mx(1)M1-x(2)UO2(NO3)3 crystals

The action of the monovalent M⁺ cations on the luminescent properties of the mixed M _x ⁽¹⁾ M _1-x ⁽²⁾ UO₂(NO₃)₃ crystals, where M is Na, K, Rb, Cs, or NH₄ , has been investigated. It has been established that the spectral positions of the bands of vibronic transitions depend linearly on the ratio between the concentrations of the M⁽¹⁰⁾ and M⁽²⁾ cations. It is shown that the crystals considered are composed of l[RbUO₂(NO₃)₃]n[CsUO₂(NO₃)₃] clusters, where l/n = x/(1 - x). The spectral regularities revealed are determined by the partial contributions of the M⁽¹⁾ and M⁽²⁾ cations to their combined, polarizing action on the uranyl complex and are explained by the ligand nature of its highest occupied molecular orbital.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 827–830, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

On the rise of the proton structure function F2 towards low x

A measurement of the derivative (∂ lnF₂/∂ lnx)_Q²≡−λ(x,Q²) of the proton structure function F₂ is presented in the low x domain of deeply inelastic positron–proton scattering. For 5×10⁻⁵x0.01 and Q²1.5 GeV², λ(x,Q²) is found to be independent of x and to increase linearly with lnQ².     

High-resolution infrared study of the 2ν3 (A1, E) and ν1 + ν3 (E) bands of NF3

The 2ν₃ overtone (A₁, E) and the ν₁ + ν₃ (E) combination bands of the oblate symmetric top ¹⁴NF₃ were studied by FTIR spectroscopy with a resolution of 2.5 × 10⁻³ cm⁻¹. Nearly 500 lines up to K_max/J_max = 30/43 were observed for the weak A₁ component reaching the v₃ = 2⁰ substate (1803.1302 cm⁻¹), the majority of which corresponded to reinforced K = 3p-type transitions. For the strong E component reaching the v₃ = 2^±2 substate (1810.4239 cm⁻¹), about 3550 transitions were assigned up to K_max/J_max = 65/69, favoring a clear observation of the ℓ(4, −2) and ℓ(4, 4) splittings within the kℓ = −2 and +4 sublevels, respectively. The two v₃ = 2 substates are linked by the ℓ(2, 2)- and ℓ(2, −1)-type interactions, providing severe crossings, respectively, at K′ = 6 and near K′ = 24 on the v₃ = 2⁺² side. A model working in the D-reduction and including all these ℓ-type interactions could reproduce together 3695 nonzero weighted experimental data (NZW) through 33 free parameters with a standard deviation of σ = 0.357 × 10⁻³  cm⁻¹. As for the ν₁ + ν₃ (E) combination band, about 3690 lines were assigned up to K_max/J_max = 45/55. Its v₁ = v₃ = 1 upper state (1931.577 5 cm⁻¹) was treated using the same model recently applied to the v₃ = 1 (E, 907.5413 cm⁻¹) state. It yielded 21 free parameters through 3282 NZW experimental data, adjusted with σ = 0.344 × 10⁻³  cm⁻¹ in the D-reduction. For the two excited states, the small and unobserved ℓ(0, 6) interaction was tested as useless. To confirm the adequacy of the vibrationally isolated models used, some other reductions of the Hamiltonian were tried. For the v₃ = 2 state, the D-, L-, and LD-reductions led to similar σ’s, while the Q one was not successful. For the v₁ = v₃ = 1 state, the D- and Q-reductions gave comparable σ’s, while the QD-reduction was not as good. The corresponding unitary equivalence relations are generally more nicely fulfilled for the v₃ = 2 state than for the v₁ = v₃ = 1 state. The three derivable anharmonicity constants in cm⁻¹ are x₃₃ = −4.1528, g₃₃ = +1.8235 and x₁₃ = −7.9652.     

q-Fuzzy Spheres and Quantum Differentials on Bq[SU2] and Uq(su2)

We provide a new unified construction of the two-parameter Podleś two-spheres as characterised by a projector e with trace _q (e) = 1 + λ. In our formulation the limit in which q → 1 with λ fixed is the fuzzy sphere, while the limit λ → 0 with q fixed is the standard q-deformed sphere. We show further that the non-standard Podleś spheres arise geometrically as ‘constant time slices’ of the unit hyperboloid in q-Minkowski space viewed as the braided group B _q [SU ₂]. Their localisations are then isomorphic to quotients of U _q (su ₂) at fixed values of the q-Casimir precisely q-deforming the fuzzy case. We also use transmutation and twisting theory to introduce a C_q[G_\mathbb C]{C_q[G_\mathbb {C}]} -covariant differential calculus on general B _q [G] and U _q (g), with Ω(B _q [SU ₂]) and Ω(U _q (su ₂) given in detail. To complete the picture, we show how the covariant calculus on the 3D bicrossproduct spacetime arises from Ω(C _q [SU ₂]) prior to twisting.     

The 2D {P} Spin-Echo-Difference Constant-Time [C, H]-HMQC Experiment for Simultaneous Determination of JH3′P and JC4′P in C-Labeled Nucleic Acids and Their Protein Complexes

A two-dimensional {³¹P} spin-echo-difference constant-time [¹³C, ¹H]-HMQC experiment (2D {³¹P}-sedct-[¹³C, ¹H]-HMQC) is introduced for measurements of ³J_C4′P and ³J_H3′P scalar couplings in large ¹³C-labeled nucleic acids and in DNA–protein complexes. This experiment makes use of the fact that ¹H–¹³C multiple-quantum coherences in macromolecules relax more slowly than the corresponding ¹³C single-quantum coherences. ³J_C4′P and ³J_H3′P are related via Karplus-type functions with the phosphodiester torsion angles β and ε, respectively, and their experimental assessment therefore contributes to further improved quality of NMR solution structures. Data are presented for a uniformly ¹³C, ¹⁵N-labeled 14-base-pair DNA duplex, both free in solution and in a 17-kDa protein–DNA complex.     

The ν1 and ν3 stretching fundamental bands of PD3

The infrared (IR) spectrum of PD₃ has been recorded in the 1580–1800 cm⁻¹ range at a resolution of 0.0027 cm⁻¹. About 2400 rovibrational transitions with J^′=K^′22 have been measured and assigned to the ν₁ (A₁) and ν₃ (E) stretching fundamentals. These include 506 “perturbation-allowed” transitions with selection rules Δ(k−l)=±3. Splittings of the K^′′=3 lines have been observed. Effects of strong perturbations are evident in the spectrum. Therefore the rovibrational Hamiltonian adopted for the analysis explicitly takes into account the Coriolis and k-type interactions between the v₁=1 and v₃=1 states, and includes also several essential resonances within these states. The rotational structure in the v₁=1 and v₃=1 vibrational states up to J^′=K^′=18 was reproduced by fitting simultaneously all experimental data. Thirty-four parameters reproduced 1950 transitions retained in the final cycle with a standard deviation of the fit equal to 4.9 × 10⁻⁴ cm⁻¹ (about the precision of the experimental measurements).     

三明治结构Tan(B3N3H6)n+1 团簇的磁性和量子输运性质

利用密度泛函理论和非平衡格林函数方法, 本文对小尺寸团簇Ta_n(B₃N₃H₆)_n+1 (n ≤ 4)的磁性和量子输运性质进行了系统的研究. 计算结果表明, 此类体系采用三明治结构作为其基态并且具有较高的稳定性. 体系的磁矩随团簇尺寸的增大而线性增大. 当把Ta_n(B₃N₃H₆)_n+1团簇耦合到Au电极上时, 形成的Au-Ta_n(B₃N₃H₆)_n+1-Au体系在有限偏压下展示出了较强的自旋过滤能力, 因而可以被看做是一类新型的低维自旋过滤器.     

Lateral restorable characteristics of the high-Tc superconducting maglev vehicle above the permanent magnet guideway

The lateral restorable characteristics of a translational symmetry high-T_c superconducting maglev system are investigated by measuring its resonant frequency (f_RF) after a lateral displacement. The difference between whether this lateral displacement is restorable, meaning elastic or inelastic, is determined by whether or not the maglev body returns to its original position after a lateral displacement. The maximum restorable lateral displacement (δ_MRLD) is determined by the sudden change of the f_RF vs. the maximum lateral displacement (δ_MLD) curve. The f_RF of the high-T_c superconducting maglev system with different field-cooling height (FCH) and working height (WH) was obtained from the frequency domain vibration curve which was measured by a vibration measurement system. The results showed that, the δ_MRLD was reduced when the WH was decreased. The maximum restorable guidance force (F_MRGF) was found to not always increase with the lowering of the WH for the same FCH. The lateral restorable stiffness (k_LRS) was always enhanced with the decrease of the WH. The decrease of the δ_MRLD with the WH is interpreted by the fact that, the tangential field component (ΔH) across the surface of the high-T_c superconductor (HTSC) is easier to exceed the J_cλ value (J_c is the critical current density and λ is the London penetration depth) when the WH is lowered, and this makes the trapped flux lines become more susceptible in escaping its pinning sites.     

Laser-induced fluorescence of Na2 at the Na(3s → 5s) two-photon transition (6022.3 Å)

Na₂ excited from the X¹Σ_g⁺ state to the A¹Σ_u⁺ state by a narrow band (3 MHz) Rhodamine-6G dye laser at 6022.3 Å, the same wavelength at which Na undergoes the 3s–5s two-photon transition, gives four fluorescence series from A¹Σ_u⁺ levels (v′ = 21, J′ = 26), (18, 33), (33, 19), and (34, 50). The last two series are much weaker in intensity, and at long wavelengths many doublets are lost in the background noise. The same (34, 50) fluorescence series was found by other workers in the lab using a Kr⁺ (5682 Å) laser as excitation source. Their analysis agrees very well with the findings in the work.     

On the profile of temperature dependent electrical and dielectric properties of Au/SiO2/n-GaAs (MOS) structures at various frequencies

The temperature (T) dependence of electrical and dielectric characteristics such as series resistance (R_s), dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tan δ), and real and imaginary part of electrical modulus (M′ and M″) of the Au/SiO2/n-GaAs (MOS) structures have been investigated in the temperature range of 80–350 K at various frequencies by using experimental capacitance (C) and conductance (G/w) measurements. Experimental results show that both C and G/w characteristics were quite sensitive to frequency and temperature at especially high temperatures and low frequencies due to a continuous density distribution of interface states and their relaxation time, and thermal restructuring and reordering of the interface. Series resistance values of this device obtained from Nicollian method decrease with increasing frequency and temperature. The ε′, ε″, tan δ, and M′ and M″ were found a strong function of frequency and temperature. While the values of ε′, ε″, and tan δ decrease, M′ and M″ increase with increasing frequency. Also, while ε′ and ε″ increase, M′ and M″ decrease with increasing temperature. The tan δ and M′ values are almost independent temperature especially at high frequencies (f≥500 kHz).     

Integrability ofSU(N) spin chains with elliptic exchange

For some one-parameter setH _N of linear combinations ofN(N−1)/2 elementary transpositions {P _jk} (1≤j<k≤N) at arbitrary naturalN≥3 one can construct a variety {I _m} (3≤m≤N) of operators which commute withH _N. Being applied toSU(n) spin representations of the permutation group, this proves the integrability of 1D periodic spin chains with elliptic short-range interaction. Presented at the 9th Colloquium “Quantum Groups and Integrable Systems”, Prague, 22–24 June 2000.     

Optical studies of phase transitions in oxyfluoride (NH4)2NbOF5

Polarization-optical studies and measurements of the birefringence Δn and the angle of rotation of the optical indicatrix for the (NH₄)₂NbOF₅ crystal have been carried out in the temperature range 100–350 K. Two anomalies of the birefringence have been revealed at the temperatures T ₀₁ = 258 K and T ₀₂ ≈ 219 K. According to the twinning pattern, the crystal undergoes successive changes in symmetry: orthorhombic ↔ monoclinic 1 ↔ monoclinic 2. The twofold axis of the monoclinic phases (or the normal to the plane) is directed along [001]_or. The effect of the uniaxial compression along [011]_or and the electric field E ≈ 25 kV/cm along [100]_or on the twin structure has been studied. The ferroelastic phase transition at T ₀₁ is due to the appearance of the shear deformation x ₄(T) and is accompanied by significant anomalies of the birefringence. Strong pretransition phenomena mask the jumps in the birefringence Δn(T) and in the angle of rotation of the indicatrix φ(T) at T ₀₁.     

The parameter in an Sp(2N)×U(1) model

We present a model based upon the gauge group Sp(2N)×U(1) which contains the SU(2)×U(1) electroweak model as an exact subsector. The parameter in this symplectic model is calculated to leading order in 1/N. We illustrate the general dependence of upon the Higgs coupling constant λ with particular interest in th e large λ limit. Finally, the 1/N result is compared with conventional one-and two-loop expressions for in the standard model.     

Study of [Fe(pyim)3] complexes: dynamic spin equilibrium on encapsulation in zeolite Y

Tris complex of Fe^II2(2′-pyridyl)imidazole has been encapsulated in the supercages of zeolite Y and characterized by using powder XRD, FTIR, Mössbauer spectroscopy, variable temperature magnetization and MAS NMR techniques and results have been compared with those obtained for this complex with ClO₄⁻ and SO₄²⁻ as anions. At room temperature, the [Fe(pyim)₃](ClO₄)₂ complex exhibited low spin state, while [Fe^II(pyim)₃]SO₄ exhibited the existence of both low and high spin states. The encapsulated [Fe^II(pyim)₃]²⁺ complex exhibited a broad quadrupole doublet characterized by isomer shift, δ=+0.55 mm/s and quadrupole splitting ΔE_q=1.26 mm/s. The magnetization measurements carried out for the encapsulated [Fe^II(pyim)₃]²⁺ complex showed a systematic decrease in its values with decreasing temperature down to 75 K with no indication of thermal hysteresis effects. These results suggest the existence of a dynamic spin state equilibrium between the high and low spin states for the encapsulated [Fe^II(pyim)₃]²⁺ complex with time constant comparable to the characteristic Mössbauer time scale of ⁵⁷Fe nuclei.