Lead(II) complexes of 2,2′-diamino-4,4′-bithiazole (DABTZ) including crystal structure of a novel 1D chain polymer, [PB(DABTZ)(μ-SCN)(μ-NO3)] n

Three new 2,2′-diamino-4,4′-bithiazole (DABTZ) lead(II) complexes were synthesized and characterized by elemental analyses, IR-, ¹H-NMR-, and ¹³C-NMR-spectroscopy. The single crystal X-ray structural analysis of [Pb(DABTZ)(μ-SCN)(μ-NO₃)] _n shows the complex to be a 1D chain polymer as a result of sequential thiocyanate and nitrate bridging. The Pb atoms are seven-coordinated by two nitrogen atoms of the 2,2′-diamino-4,4′-bithiazole, three nitrate and two thiocyanate ligands. The arrangement of the 2,2′-diamino-4,4′-bithiazole, nitrate and thiocyanate ligands does not suggest a gap in the coordination around the Pb^II ion, caused by a stereo-active lone pair of electrons on lead(II) where the coordination around the lead atoms is the less common holodirected.     

Synthesis,structure and properties of aquabis(2,4′-bipyridine)di(propionato-O)copper(II)

The title complex has been synthesized and characterized by elemental and thermal analysis, IR and electronic spectroscopy, conductivity studies and X-ray crystallography. In the crystal, the complex has two-fold symmetry and the copper atom adopts square pyramidal coordination. Bond valences for Cu were computed. Cu–O_(propionate) bonds are slightly stronger than the Cu–N bonds, and the Cu–O_(water) bond is distinctly weaker. Molecules are linked by O–H···O hydrogen bonds to form infinite hydrogen-bonded chains along the y axis.     

Differential incoherent scattering of 279.2 keV photons by Zr,Sn, Ta,Pb and U

Differential incoherent scattering cross-section ratios of 279.2 keV photons by zirconium, tin, tantalum, lead and uranium elements are experimentally determined by comparing the peak areas under the degraded photon energy with that of an equivalent aluminium foil employing a high resolution 35 c.c. coaxial Ge(Li) detector. Studies have been made in single configuration in an angular range of 20° to 115°. The results are compared with theoretical values obtained from the non-relativistichfs model of Hubbell and co-workers. The cross-section ratios decrease as the atomic number increases for a given scattering angle.     

Realization of a unique time evolution unitary operator in Klein Gordon theory

The scattering theory for the Klein Gordon equation, with time-dependent potential and in a non-static space-time, is considered. Using the Klein Gordon equation formulated in the Hubert spaceL ²(R ³) and the Einstein’s relativistic equation in the spaceL ²(R ³, dx) and establishing the equivalence of the vacuum states of their linearized forms in the Hubert spaceL ²(R ³) with the help of unique symmetric symplectic operator, the time evolution unitary operatorU(t) has been fixed for the Klein Gordon equation, incorporating either the positive or negative frequencies, in the infinite dimensional Hubert spaceL ²(R ³).     

Neutron excitation of landau and collective modes in a magnetized plasma

Summary The response function for magnetic neutron scattering off electrons forming a one-component plasma, or jellium model, subject to a steady magnetic field, is calculated in the semi-classical limit in which Boltzmann statistics apply to the electron states. A complete expression for the response of an ideal plasma is given in a compact, closed form, amenable to numerical investigation, and including the dependence on electron parameters such as effective mass and gyromagnetic ratio. Effects due to the Coulomb interaction are discussed within the limitations of the random phase approximation. The theoretical results are used to predict the conditions that must obtain for the observation of neutron excitation of Landau and collective modes.

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Riassunto La funzione di risposta per lo scattering magnetico dei neutroni dagli elettroni che forma un plasma ad un componente, o modello di jellio, soggetto ad un campo magnetico fisso, è calcolata nel limite semiclassico nel quale la statistica di Boltzmann si applichi agli stati elettronici. Si dà un’espressione completa per la risposta di un plasma ideale in una forma compatta e chiusa adatta alla ricerca numerica e che include la dipendenza dai parametri elettronici come la massa efficace ed il rapporto giromagnetico. Si discutono gli effetti dovuti all’interazione di Coulomb entro i limiti dell’approssimazione di fase random. I risultati teorici sono usati per prevedere le condizioni che devono essere ottenute dall’osservazione dell’eccitazione dei neutroni di Landau e dei modi collettivi.

     

High pressure raman scattering in Pb5Ge3O11

The pressure dependence of various phonon modes has been investigated through the ferro-paraelectric phase transition. Most mode frequencies harden before levelling off above the phase transition. Mode Grüneisen parameters are estimated from the pressure dependence of phonon frequencies.     

热丝CVD生长金刚石薄膜喇曼散射研究

本文报道热丝化学气相沉积法（ＨＦＣＶＤ）生长金钢石薄膜的喇曼散射结果。选取多种峰型，对金钢石薄膜喇曼谱（１１０－１８００ｃｍ－１）采用最小二乘法进行非线性拟合，得到最佳拟合模型，其计算得到的拟合曲线怀实验谱图符合得较好。该模型揭示，石墨Ｄ峰（１３５５ｃｍ－１）是金刚石薄膜喇曼谱中不可缺少的一个组份，并且结合石墨Ｄ峰和金刚石喇曼的空间相关线型，可以解释金刚石喇曼区特殊峰形的物理机制，拟合参量的进一步     

Bone-ablation mechanism using CO2 lasers of different pulse duration and wavelength

Bone ablation using different pulse parameters and four emission lines of 9.3, 9.6, 10.3, and 10.6 m of the CO₂ laser exhibits effects which are caused by the thermal properties and the absorption spectrum of bone material. The ablation mechanism was investigated with light- and electron-microscopy at short laser-pulse durations of 0.9 and 1.8 s and a long pulse of 250 s. It is shown that different processes are responsible for the ablation mechanism either using the short or the long pulse durations. In the case of short pulse durations it is shown that, although the mineral components are the main absorber for CO₂ radiation, water is the driving force for the ablation process. The destruction of material is based on explosive evaporation of water with an ablation energy of 1.3 kJ/cm³. Histological examination revealed a minimal zone of 10–15 m of thermally altered material at the bottom of the laser drilled hole. Within the investigated spectral range we found that the ablation threshold at 9.3 and 9.6 m is lower than at 10.3 and 10.6 m. In comparison the ablation with a long pulse duration is determined by two processes. On the one side, the heat lost by heat conduction leads to carbonization of a surface layer, and the absorption of the CO₂ radiation in this carbonized layer is the driving force of the ablation process. On the other side, it is shown that up to 60% of the pulse energy is absorbed in the ablation plume. Therefore, a long pulse duration results in an eight-times higher specific ablation energy of 10 kJ/cm³.     

Influence of Low-Intensity Laser Radiation on the Rheological Characteristics of Human Blood

The influence of low-intensity laser radiation (LLR) on the rheological characteristics of human blood has been investigated. The results of the investigation of the blood velocity in the human skin capillaries, the erythrocyte aggregation time, and the spectral width of scattering intensity fluctuations depending on the irradiation time are presented. It has been shown that laser irradiation leads to a decrease in the degree of aggregation of erythrocytes and, accordingly, to an increase in the velocity of blood microcirculation, which can be used for laser therapy and diagnostics and treatment of cardiovascular diseases (CVD). To explain the results obtained, a method of the LLR–biotissue interaction is proposed.     

Effects of molecular gases on Xe electroluminescence and electron resonance trapping

Summary Xenon electroluminescence (EL) has been studied in the presence of small amounts of molecular gases and some results are reported. A theoretical model, which explains the EL in terms of a peak in the electron energy distribution near the energy of subexcitative resonance at 7.77 eV (electron resonance trapping), was developed to take into account the effects of a molecular gas present at low concentrations. The results obtained with air, at concentrations lower than 10³ p.p m., seem to fit well the developed model. Supported in part by GNEQP-C.N.R.