Influence of the sample orientation in Sn<Subscript>2</Subscript>P<Subscript>2</Subscript>S<Subscript>6</Subscript> crystals on the hydrostatic piezoelectric coefficients

The influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients d _h ⁽ⁱ⁾ of Sn₂P₂S₆ crystals has been studied. The hydrostatic piezoelectric coefficients d _h ⁽¹⁾ and d′ _h ⁽³⁾ , were measured, d _h ⁽¹⁾ =(244±3) pC/N and d′ _h ⁽³⁾ =(92±1) pC/N. The hydrostatic piezoelectric coefficient d _h ⁽³⁾ for orthogonal axis system was calculated to be d _h ⁽³⁾ =(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d _h ⁽¹⁾ equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d _h ) _mean corresponding to randomly oriented Sn₂P₂S₆ grains in a poled composite has been calculated to be (d _h ) _mean =136 pC/N.     

The connection between photon mass andB (3) : The poincaré group

The longitudinal vacuum fieldB ⁽³⁾ is an experimental observable which produces by magnetization a well-defined square-root beam power density dependence. Its longitudinal polarization implies that the helicities of the photon are +1, 0, and –1, and that the little group of the Poincaré group is the rotation group 0(3) of a massive boson. The mass of the photon (m) is therefore related directly toB ⁽³⁾ through the Proca equation, and it is concluded that experimental evidence forB ⁽³⁾ is also evidence for finitem.     

Thermodynamic investigations of ternary o-toluidine + tetrahydropyran + N,N-dimethylformamide mixture and its binaries at 298.15, 303.15 and 308.15 K

The densities ρ, speed of sound u, data of o-toluidine (i) + tetrahydropyran (j) + N,N-dimethylformamide (k) and its {tetrahydropyran (j) + N,N-dimethylformamide (k); o-toluidine (i) + N,N-dimethylformamide (k)} binaries have been measured as a function of composition at 298.15, 303.15 and 308.15 K. The excess molar enthalpies, H^E data of same set of binary mixtures have also been measured over entire composition at 308.15 K. The densities and speeds of sound data of binary and ternary mixtures have been utilized to determine their excess molar volumes, V^E and excess isentropic compressibilities, κ_S^E. The observed thermodynamic properties of binary and ternary mixtures have been analyzed in terms of Graph theory. It has been observed that Graph theory correctly predicts the sign as well as magnitude of thermodynamic properties.     

First analysis of the ν5 band of DNO3 (deuterated nitric acid) in the 11 μm region

The infrared spectrum of DNO₃ (deuterated nitric acid) was recorded at high resolution (0.0027 cm⁻¹) in the 700-1400 cm⁻¹ region on a Bruker IFS 120 HR Fourier transform spectrometer. The analysis of the ν₅ band of DNO₃ centred at 887.657 cm^-1 which is mostly an A-type band, was performed making use of the ground state parameters achieved by Drouin et al. [Drouin BJ, Miller CE, Fry JL, Petkie DT, Helminger P, Medvedev IR. J Mol Spectrosc 2006;236:29-34]. The ν₅ fundamental band is strongly perturbed because of the existence of the ν₇+ν₉ dark combination band at 882.21  cm^-1. The 5¹ and 7¹9¹ energy levels of DNO₃ are coupled through A and B type Coriolis resonances, and as a consequence, numerous lines from the ν₇+ν₉ dark combination band could be identified also. In this way about 1070 and 75 energy levels of the 5¹ and 7¹9¹ vibrational states, respectively, were satisfactorily reproduced by the energy levels calculation which account for the observed resonances. A reasonable estimation of the absolute line intensities for the ν₅ band of DNO₃ was performed using the ν₅ transition operator from H¹⁴NO₃. The spectrum also features the ν₅+ν₆−ν₆, ν₅+ν₇−ν₇ and ν₅+ν₉−ν₉ hot bands located at 881.03, 882.61 and 884.45 cm⁻¹, respectively.     

Proton scattering from unstable nuclei

Recent improvements in the intensities and optical qualities of radioactive beams have made possible the study of elastic and inelastic proton scattering on unstable nuclei. The design and performances of an innovative silicon strip detector array devoted to such experiments are described. The quality of the data obtained are illustrated with recent results obtained at the GANIL facility for unstable oxygen, sulfur and argon isotopes. Methods to analyse the data using phenomenological and microscopic optical model potentials are discussed.     

The Degenerate Vibrations of BCl3, BBr3 and BI3 with Application of Keating Coordinates

The experimental works of vibrational spectroscopy and normal coordinate analyses for BCl₃, BBr₃ and BI₃ are reviewed extensively. Harmonic force fields of the E' species are produced using isotopic frequencies and Coriolis constants as additional data, respectively. The usefulness of Keating coordinates versus valence coordinates as basis of force field approximations is discussed. The conclusions are not unequivocal, but they go in favour of the Keating coordinates when the reliability of the different computations is taken into account. Boron trichloride is treated specifically in some detail. Final force fields are proposed for the title molecules with the aid of the mass influence on Coriolis constants.     

One-neutron knockout from Ne isotopes

One-neutron knockout reactions of ^24–28Ne in a beryllium target have been studied in the Fragment Separator (FRS), at GSI. The results include inclusive one-neutron knockout cross-sections as well as longitudinal-momentum distributions of the knockout fragments. The ground-state structure of the neutron-rich neon isotopes was obtained from an analysis of the measured momentum distributions. The results indicate that the two heaviest isotopes, ²⁷Ne and ²⁸Ne, are dominated by a configuration in which a s_1/2$s_{1/2}$ neutron is coupled to an excited state of the ²⁶Ne and ²⁷Ne core, respectively.     

NQR, NMR and Crystal Structure Studies of [C(NH2)3]2HgX4 (X = Br, I)

The crystal structure of [C(NH₂)₃]₂HgBr₄ has been determined at room temperature: monoclinic, space group C2/c, with a = 10.035(2), b = 11.164(2), c = 13.358(3) Å, β = 111.67(3)°, and Z = 4. The crystal consists of planar [C(NH₂)₃]⁺ and distorted tetrahedral [HgBr₄]^2? ions. The Hg atom is located on a two-fold axis such that two sets of inequivalent Br atoms exist in an [HgBr₄]^2? ion. In accordance with the crystal structure, two ⁸¹Br NQR lines widely separated in frequency were observed between 77 and ca. 380 K. [C(NH₂)₃]₂HgI₄ yielded four ¹²⁷I NQR lines ascribable to m = ±1/2 ? ±3/2 transitions, indicating that its crystal structure is different from the bromide complex. The ¹H NMR T ₁ measurements showed a single minimum for the bromide but two minima for the iodide. The analyses based on the C₃ reorientations of the planar [C(NH₂)₃]⁺ ions gave the activation energies of 29.8 kJ mol^?1 for the bromide, and 30.2 and 40.0 kJ mol^?1 for the iodide.     

Production of hypernuclei with the reaction

We present results on the production of bound states of Θ⁺ in nuclei using the (K⁺,π⁺) reaction. By taking into account the states obtained within a wide range of strength of the Θ⁺ nucleus optical potential, plus the possibility to replace different nucleons of the nucleus, we obtain an excitation spectra with clearly differentiated peaks. The magnitude of the calculated cross sections is well within reachable range.     

Depth profiling of cells and tissues by using C60 and SF5 as sputter ions

In the present study, SF₅⁺ and C₆₀⁺ were used as primary ions for sputtering and Bi₃⁺ was used as primary ions for analysis. The depth profiling procedure was utilized to make 3D images of the chemistry of single cultured cells and tissue samples of intact intestinal epithelium.The results show sputtering of organic material from cells and tissue with both SF₅⁺ and C₆₀⁺ sources. Cholesterol fragments were found in the superficial layers when sputtering with C₆₀⁺. Spectra were collected revealing the change in yield along the z-axis of the sample. 3D images of the localization of Na, K, phosphocholine and cholesterol were constructed with both ion sources for single cell cultures and the mouse intestine.Cryostate sections of mouse intestine were analysed in 2D and the results were compared with the 3D image of the intestine. The localization of cholesterol and phosphocholine was found to be similar in cryostate sections analysed in two dimensions and the sputtered, freeze-dried intestine analysed in 3D. The comparison of 2D and 3D images suggest that the phosphocholine signal faded with C₆₀⁺ sputtering. In conclusion, both C₆₀⁺ and SF₅⁺ can be used as primary ion sources for sputtering of organic material from cells and tissues. Consecutive analysis with a Bi₃⁺ source can be used to obtain image stacks that could be used for reconstruction of 3D images.     

NQR, NMR and Crystal Structure Studies of [C(NH2)3]3Sb2Br9

The crystal structure of [C(NH₂)₃]₃Sb₂Br₉ was determined at 143 K: monoclinic, space group C2/c, Z = 4, a = 15.695 (3), b = 9.039(2), c = 18.364(3) Å, β = 96.94(1)°. The structure consists of two crystallographically independent guanidinium ions and two-dimensional corrugated sheets of (Sb₂Br₉ ^3?) _n , in which SbBr₆ octahedra are connected through three bridging Br atoms each other. One of the cations situates in a cavity of the (Sb₂Br₉ ^3?) _n layer with statistical disorder, while the other situates between the layers without disorder. Three ⁸¹Br NQR resonance lines were assignable to terminal Br atoms, while only one line was found for two inequivalent bridging Br atoms. All the ⁸¹Br NQR resonance lines were subjected to fade-out at low temperatures. The temperature dependence curve of ¹H NMR T ₁ showed well defined two minima, which were explained by postulating the C₃ reorientations of two types of cations with very different activation energies. The DTA (DSC) measurement revealed a phase transition of a first-order type at 444 K.     

Study of Be + C elastic scattering at energies near the Coulomb barrier

In this work, angular distribution measurements for the elastic channel were performed for the ⁹Be + ¹²C reaction at the energies ELab=13.0$E_{\mathit{Lab}}=13.0$, 14.5, 17.3, 19.0 and 21.0 MeV, near the Coulomb barrier. The data have been analyzed in the framework of the double folding São Paulo potential. The experimental elastic scattering angular distributions were well described by the optical potential at forward angles for all measured energies. However, for the three highest energies, an enhancement was observed for intermediate and backward angles. This can be explained by the elastic transfer mechanism.     

The B 2Σ+–X 2Σ+ Transition of 12C17O+: The 2‐υ″ Progression

Abstract

Three new bands of the B ²Σ⁺–X ²Σ⁺ system of ¹²C¹⁷O⁺ have been investigated using conventional spectroscopic techniques. The spectra were observed in a graphite hollow‐cathode lamp by discharging molecular oxygen (enriched in about 45% of the ¹⁷O₂ isotope) under 1.0 Torr pressure. The rotational analysis of the 2–4, 2–5, and 2–6 bands was performed with the effective Hamiltonian of Brown (Brown et al., J. Mol. Spectrosc. 1979; 74: 294–318). Molecular constants were derived from a merge calculation, including both the current wavenumbers and the spectroscopic data published by the authors previously. The principal equilibrium constants for the ground state of ¹²C¹⁷O⁺ are ω_e=2185.9658(84), ω_e x _e = 14.7674(11), B _e=1.927001(38), α_e=1.8236(22)×10^?2, γ_e=?0.331(28)×10^?4, D _e=6.041(12)×10^?6, β_e=0.100(31)×10^?7 cm^?1, and the equilibrium constants for the excited state are σ_e=45876.499(15), ω_e=1712.201(12), ω_e x _e=27.3528(39), B _e=1.754109(35), α_e=2.8706(57)×10^?2, γ_e = ?1.15(19)×10^?4, D _e=7.491(20)×10^?6, β_e=2.13(12)×10^?7, γ_e = 2.0953(97)×10^?2, and α_γe=?9.46(59)×10^?4 cm^?1, respectively. Rydberg–Klein–Rees potential energy curves were constructed for the B ²Σ⁺ and X ²Σ⁺ states of this molecule, and Franck–Condon factors were calculated for the vibrational bands of the B–X system.     

Noise spectrum of charge current in a quantum dot system under the irradiation of quantum electromagnetic field

We have investigated the noise spectrum of a quantum dot (QD) coupled to two normal metal leads under the perturbation of a quantum electromagnetic field (QEMF) by nonequilibrium Green?s function method. Current correlation function is determined through making the ensemble average over the lowest SU(1,1)$\mathrm{SU}(1,1)$ coherent state. The fluctuation of QEMF makes important contribution to the noise by imposing an additional term, and quantum feature of the QEMF is transferred to the shot noise. The total noise of our system is composed of three parts: the thermal noise, the quantum field noise, and the shot noise. The quantum field noise is generated from the QEMF, and it dominates the total noise. The shot noise and quantum field noise belong to different types, and they display quite differently. The stair-like and photon-assisted behaviors are obviously exhibited. The enhancement and suppression of noise can be controlled by adjusting the parameters according to its behaviors.     

Effect of continuous layer in CGC perpendicular recording media

The effect of continuous layer on CoCrPt–SiO₂ granular layer is studied in coupled granular continuous (CGC) perpendicular recording media. In the cross-section transmission electron microscope (TEM) observation, magnetic grain in the granular layer shows columnar structure, while Co/Pd multilayer shows continuous layer. The plane-view TEM image of the granular layer shows well-isolated grain structure with average grain size of around 6 nm, and grain-to-grain separation width of around 2 nm. Therefore, the interactions among the grains are negligible (J∼0). By depositing a continuous layer on a CoCrPt–SiO₂ granular layer, the grains in the granular layer are magnetically coupled through capping layer that leads to the suppression of magnetic anisotropy dispersion. This CGC structure reduces the coercivity dispersion (Δ_Hc/_Hc$\mathrm{\Delta }{H}_{\mathrm{c}}/H_{\mathrm{c}}$) from 0.26 to 0.15 and saturation field (H_s) from 10.4 to 6.7 kOe. The reduction of H_s and Δ_Hc/_Hc$\mathrm{\Delta }{H}_{\mathrm{c}}/H_{\mathrm{c}}$ improves the OW by 21.3 dB. The small Δ_Hc/_Hc$\mathrm{\Delta }{H}_{\mathrm{c}}/H_{\mathrm{c}}$ also maintains SNR of CGC media with strong magnetic exchange coupling. Furthermore, the coupling of grains through continuous layer enlarges the magnetic nucleation field (H_n) from 0.4 to −1.7 kOe. Consequently, CGC media shows better thermal stability compared to non-CGC media.     

One- and two-dimensional C–H/N–H dipolar correlation experiments under fast magic-angle spinning for determining the peptide dihedral angle φ

A recently proposed ¹³C–¹H recoupling sequence operative under fast magic-angle spinning (MAS) [K. Takegoshi, T. Terao, Solid State Nucl. Magn. Reson. 13 (1999) 203–212.] is applied to observe ¹³C–¹H and ¹⁵N–¹H dipolar powder patterns in the ¹H–¹⁵N–¹³C–¹H system of a peptide bond. Both patterns are correlated by ¹⁵N-to-¹³C cross polarization to observe one- or two-dimensional (1D or 2D) correlation spectra, which can be simulated by using a simple analytical expression to determine the H–N–C–H dihedral angle. The 1D and 2D experiments were applied to N-acetyl[1,2-¹³C,¹⁵N] -valine, and the peptide φ angle was determined with high precision by the 2D experiment to be ±155.0°±1.2°. The positive one is in good agreement with the X-ray value of 154°±5°. The 1D experiment provided the value of φ=±156.0°±0.8°.     

Relative vibrational transition probabilities in the (B 3 π g−A 3Σ u + ) system of nitrogen for Hulbert-Hirschfelder oscillator model

Hulbert-Hirschfelder (h-h) potential function has been used to obtain the relative vibrational transition probabilities for the observed bands of the first positive system of nitrogen molecule. The vibrational wavefunctions have been calculated by solving the Schrödinger equation by the method due to Langer, at low vibrational quanta and by thewkb method at high vibrational quanta. It is established that theh-h potential is superior to the often used Morse potential function for the transition under consideration.     

The First in Vivo Observation of C–N Coupling in Mammalian Brain

[5-¹³C,¹⁵N]Glutamine, with ¹J(¹³C–¹⁵N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by ¹³C MRS at 4.7 T. The brain [5-¹³C]glutamine peak consisted of the doublet from [5-¹³C,¹⁵N]glutamine and the center [5-¹³C,¹⁴N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-¹³C,¹⁵N]glutamine was monitored in vivo with a time resolution of 20–35 min. This [5-¹³C,¹⁵N]glutamine was formed by glial uptake of released neurotransmitter [5-¹³C]glutamate and its reaction with ¹⁵NH₃ catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively¹³C-enriched by intravenous [2,5-¹³C]glucose infusion to ¹³C-label whole-brain glutamate C5, followed by [¹²C]glucose infusion to chase ¹³C from the small and rapidly turning-over glial glutamate pool, leaving ¹³C mainly in the neurotransmitter [5-¹³C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-¹³C,¹⁵N]glutamine arises from a coupling between ¹³C of neuronal origin and ¹⁵N of glial origin. Measurement of the rate of brain [5-¹³C,¹⁵N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.     

HD+2，H+3和D+3与固体相互作用和三体尾流效应

从分子离子H⁺₃及其氘化同位素分子离子D⁺₃和HD⁺₂与超薄固体膜相互作用发生库仑爆炸为基础,分析讨论了H⁺₃,D⁺₃和HD⁺₂三种分子离子的形成机理,根据产物能谱分布,利用库仑爆炸技术确定了同位素分子离子HD⁺₂的结构形式,给出具体核间距数值.并确定在实验中不存在线状结构的HD⁺₂.提出一种三原子分子离子和固体相互作用中尾流效应的处理方式,通过和实验结果做比较发现这是一种非常理想的处理三体尾流效应的模式,并用之进一步确认了HD⁺₂的结构形状.文章对H⁺₃,D⁺₃和HD⁺₂三种分子离子的实验结果做了对比和讨论. 关键词： +₂')" href="#">微团簇HD⁺₂ +₃和D⁺₃')" href="#">H⁺₃和D⁺₃ 库仑爆炸 三体尾流势 团簇结构