[Study on Vibrational Spectra Characteristics of Gem-Quality Natrolite].

Recently, there is a batch of colorless faceted gem-quality natrolite appear in the international jewelry market. In order to provide some information that can help us to distinguish them from the imitations. The infrared spectrometer and Raman spectrometer were employed to study the characteristics of the vibrational spectrum of three natrolite samples in this article. The typical infrared spectra shows that: the absorption region 4000~1200 cm(-1) is induced by stretching vibration of the hydroxyl group, the strong absorption peaks range from 1200~600 cm(-1) are relative with the anti-symmetry and symmetry stretching vibration of tetrahedral T-O bonds (T=Si or Al). The Raman spectra scattering peaks are located in the range of 300~600 and 700~1200 cm(-1). The low intensity Raman scattering spectrum in the range of 300~360 cm(-1) corresponds to the vibration of the water molecules in the crystal. The medium intensity Raman scattering spectrum is assigned to the deformation of SiO4 tetrahedra. The Raman spectra scattering peak at 726 cm(-1) is assigned to the stretching vibration of Al-O; The Si-O stretching vibration displays the Raman spectra scattering peaks at 974, 1038 and 1084 cm(-1).

[Crystallography orientation by molecular spectrum of structural hydroxide in pyroxene megacryst].

Crystal can be crystallographically oriented by molecular spectrum with the change in band shift, band intensity, and band shape. The three groups of band shift of augite are different between vertical to c-axis and parallel to c-axis: the first peak value 3 629-3 633 red shifts to 3 601-3 616; the same as the second peak value 3 514-3 543; on the contrary, the third peak value 3 460-3 465 is blue shift. The intensity of the first band is equivalent in two directions, while the second and the third parallel to c-axis are much stronger than the vertical. The wave shape is not quite different. The intensity of the Raman spectra vertical to c-axis is stronger than that parallel to c-axis in general, while the band shift and the shape show little difference. It was indicated that the geological tectonic environment can be reflected by the spectra of structural hydroxide with different crystal directions.

catena-Poly[[diaquacadmium(II)]bis-(µ-pyridine-3-sulfonato)-κN:O;κO:N].

In the title polymeric complex, [Cd(C(5)H(4)NO(3)S)(2)(H(2)O)(2)](n), the Cd atom is located on a centre of inversion and is coordinated by two O atoms and two N atoms, derived from four different pyridine-3-sulfonate ligands, and two O atoms derived from two water mol-ecules, forming a distorted trans-N(2)O(4) octa-hedral geometry. The topology of the polymer is a one-dimensional chain mediated by bridging pyridine-3-sulfonate anions. These are connected into a three-dimensional architecture via hydrogen bonds.

catena-Poly[[diaqua-manganese(II)]-di-µ-pyridine-3-sulfonato-κN:O;κO:N].

In the title polymeric complex, [Mn(C(5)H(4)NO(3)S)(2)(H(2)O)(2)](n), the Mn atom is located on a centre of inversion and is coordinated by two O atoms and two N atoms derived from four different pyridine-3-sulfonate (pySO(3)) ligands, and two O atoms derived from two water mol-ecules in a distorted trans-N(2)O(4) octa-hedral geometry. The metal atoms are bridged by the pySO(3) ligands to form a one-dimensional chain. The chains are further connected into a three-dimensional architecture via hydrogen bonds.

A Computer Model for the Pore of Potassium Channel: Oxygen Cage Mechanism.

We have constructed a structural motif for the pore of voltage-gated K(+) channel by computer modeling. The model developed here predicts that the narrowest part of the pore is formed by the four carbonyl oxygens of Gly444 or Gly446, and that the ion selectivity is achieved through "oxygen cage" mechanism. Residues 447, 448 and 449 make the external entrance to the narrowest part of the pore. Of these residues, 449 and 447 are believed to interact directly with TEA. This model agrees well with many available experimental data.