The magic number silica clusters [(SiO(2))(n)O(2)H(3)](-) with n = 4 and 8 have been observed in the XeCl excimer laser (308 nm) ablation of various porous siliceous materials. The structural origin of the magic number clusters has been studied by the density functional theoretical calculation at the B3LYP/6-31G** level, with a genetic algorithm as a supplementary tool for global structure sear...

A series of complexes of formula TpNiX, where Tp*- = hydrotris(3,5-dimethylpyrazole)borate and X = Cl, Br, I, has been characterized by electronic absorption spectroscopy in the visible and near-infrared (NIR) region and by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy. The crystal structure of TpNiCl has been previously reported; that for TpNiBr is given here: ...

A new hexanuclear iron-selenium nitrosyl cluster, [(n-Bu)(4)N](2)[Fe(6)Se(6)(NO)(6)] (1), and a hexanuclear iron-sulfur nitrosyl cluster, [(n-Bu)(4)N](2)[Fe(6)S(6)(NO)(6)] (2), were synthesized by the solvent-thermal reactions of [(n-Bu)(4)N][Fe(CO)(3)NO] with selenium or sulfur in methanol, while a tetranuclear iron-sulfur nitrosyl cluster, (Me(4)N)[Fe(4)S(3)(NO)(7)] (3), was also prepared by ...

Although transplantation and stem cell therapies look promising, at present, type 1 (insulin-dependent) diabetics can be treated only with insulin or insulin analogues. Hexameric insulin is widely used in pharmaceutical formulations for treatment of insulin-dependent diabetes mellitus. 4] The stability and dynamic properties of human insulin (HI) zinc hexamer formulations are critically influen...

We have prepared a series of divalent cobalt(II) complexes supported by the [PhBP(3)] ligand ([PhBP(3)] = [PhB(CH(2)PPh(2))(3)](-)) to probe certain structural and electronic phenomena that arise from this strong field, anionic tris(phosphine) donor ligand. The solid-state structure of the complex [PhBP(3)]CoI (1), accompanied by SQUID, EPR, and optical data, indicates that it is a pseudotetrah...

Cd(II) has been used as a probe of zinc metalloenzymes and proteins because of the spectroscopic silence of Zn(II). One of the most commonly used spectroscopic techniques is (113)Cd NMR; however, in recent years (111m)Cd Perturbed Angular Correlation spectroscopy ((111m)Cd PAC) has also been shown to provide useful structural, speciation and dynamics information on Cd(II) complexes and biomolec...

Abstract Study question What can we learn from 3D reconstructions of cleavage-stage embryos derived Hoffman modulation contrast (HMC) time-lapses? Summary answer A simple spatial biomarker extracted embryo at the t4 and t8 stages is associated with blastulation, blastocyst quality, pregnancy live birth. known already Several works have demonstrated significant associations between cell arrangem...

In this paper, two double helical dinuclear copper(II) complexes of bis-N,O-bidentate Schiff base ligands bis(3-methoxy-N-salicylidene-4,4'-diaminodiphenyl)sulfone (L1) and bis(5-bromo-N-salicylidene-4,4'-diaminodiphenyl)sulfone (L2) were prepared and characterized by elemental analyses (CHN), as well as thermal analysis. Elemental analyses (CHN) suggested that the reaction between ligands and ...

The previously reported pseudotetrahedral Co(I) complexes, CoX(PR3)3, where R = Me, Ph, and chelating analogues, and X = Cl, Br, I exhibit a spin triplet ground state, which is uncommon for Co(I), although expected for this geometry. Described here are studies using electronic absorption and high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy on two members of this cl...

Thermodynamics of potassium (K) exchange using a kinetics approach was investigated in Ca-saturated samples from the Ap and B21t horizons of a Matapeake soil from Delaware. Kinetics of adsorption and desorption were determined at temperatures of 0, 25, and 40°C on each soil horizon using a miscible displacement technique. Energies of activation for adsorption and for desorption (£„ and Ed, resp...