Prediction of the binding mode of N2-phenylguanine derivative inhibitors to herpes simplex virus type 1 thymidine kinase

The probable binding mode of the herpes simplex virus thymidine kinase (HSV1 TK) N²-[substituted]-phenylguanine inhibitors is proposed. A computational experiment was designed to check some qualitative binding parameters and to calculate the interaction binding energies of alternative binding modes of N²-phenylguanines. The known binding modes of the HSV1 TK natural substrate deoxythymidine and one of its competitive inhibitors ganciclovir were used as templates. Both the qualitative and quantitative parts of the computational experiment indicated that the N²-phenylguanine derivatives bind to the HSV1 TK active site in the deoxythymidine-like binding mode. An experimental observation that N²-phenylguanosine derivatives are not phosphorylated during the interaction with the HSV1 TK gives support to the proposed binding mode.     

Preparation, structures and some reactions of novel diynyl complexes of iron and ruthenium

Reactions between HC triple bond CC triple bond CSiMe3 and several ruthenium halide precursors have given the complexes Ru(C triple bond CC triple bond CSiMe3)(L2)Cp'[Cp'= Cp, L = CO (1), PPh3 (2); Cp' = Cp*, L2= dppe (3)]. Proto-desilylation of 2 and 3 have given unsubstituted buta-1,3-diyn-1-yl complexes Ru(C triple bond CC triple bond CH)(L2)Cp'[Cp'= Cp, L = PPh3 (5); Cp'= Cp*, L2 = dppe (6)]. Replacement of H in 5 or 6 with Au(PR3) groups was achieved in reactions with AuCl(PR3) in the presence of KN(SiMe3)2 to give Ru(C triple bond CC triple bond CAu(PR3)](L2)Cp'[Cp' = Cp, L = PPh3, R = Ph (7); Cp' = Cp*, L2= dppe, R = Ph (8), tol (9)]. The asymmetrically end-capped [Cp(Ph3P)2Ru]C triple bond CC triple bond C[Ru(dppe)Cp*] (10) was obtained from Ru(C triple bond CC triple bond CH)(dppe)Cp* and RuCl(PPh3)2Cp. Single-crystal X-ray structural determinations of and are reported, with a comparative determination of the structure of Fe(C triple bond CC triple bond CSiMe3)(dppe)Cp* (4), and those of a fifth polymorph of [Ru(PPh3)2Cp]2(mu-C triple bond CC triple bond C) (12), and [Ru(dppe)Cp]2(mu-C triple bond CC triple bond C) (13).     

Preparation and Structures of Several Complexes Containing Carbon-Rich Ligands Attached to Polynuclear Metal Carbonyls

Several new gold-containing cluster complexes have been prepared from the reactions of gold alkynyl complexes, L _n M-C _x -Au(PPh₃), (x = 3, 4, 6) with Ru₃(CO)₁₀(NCMe)₂. The bis-cluster complex 1,4-{AuRu₃(CO)₉(PPh₃)(μ₃-C₂)}₂C₆H₄ was obtained from Ru₃(CO)₁₀(NCMe)₂ and 1,4-{(Ph₃P)Au(C≡C)}₂C₆H₄. The complexes Ru₃(μ-H){μ₃-C₂C≡C[Ru(PP)Cp′]}(CO)₉ [PP = (PPh₃)₂, Cp′ = Cp; PP = dppe, Cp′ = Cp*] were also obtained as minor by-products and synthesised independently from Ru(C≡CC≡CH)(PP)Cp′. A reaction between Co₃{μ₃-CC≡CC≡CAu(PPh₃)}(μ-dppm)(CO)₇ and Ru₃(CO)₁₂ afforded {(Ph₃P)(OC)₉AuRu₃}C≡CC≡CC{Co₃(μ-dppm)(CO)₇} 7. Related complexes AuRu₃{μ₃-C₂C≡[M(CO)₂Tp]}(CO)₉(PPh₃) (M = Mo 8, W 9) were obtained from {Tp(OC)₂M}≡CC≡C{Au(PPh₃)}, while the mixed metal cluster complexes MoM₂(C₂Me)(CO)₈Tp (M = Ru 13, Fe 14) were obtained from M(≡CC≡CSiMe₃)(CO)₂Tp (M = Mo, W) with Fe₂(CO)₉ and Ru₃(CO)₁₂, respectively. Reactions of the Mo carbyne complex with Co₂(LL)(CO)₆ [LL = (CO)₂, μ-dppm] or nickelocene afforded complexes 15–17 in which Co₂ and Ni₂ fragments, respectively, had coordinated to the C≡C triple bond. XRD structural determinations of 7, 8, 14, 16 and {Tp(OC)₂W}≡CC≡CC≡{Co₃(μ-dppm)(CO)₇} (18-W) are reported. In memoriam: F. Albert Cotton (1930–2007).     

Reduction of false alarms in forest fire surveillance using water vapour concentration measurements

In this work a theoretical model to evaluate the capabilities of our lidar system in forest fire detection is reported. In particular, a new idea of minimization of false alarm is shown. In a forest fire, in fact, a lot of ashes and in the first stage a large amount of water vapour are emitted. Measurements of water vapour increase with respect to standard humidity in the atmosphere due to a forest fire event, by means of Raman analysis, permit to minimize the false alarm. A simulation of one case of study permits to estimate the maximum range of detection and minimum sensibility of our lidar system. In this paper the theoretical results are shown.     

Observation of a pressure-induced first-order polyamorphic transition in a chalcogenide glass at ambient temperature

An apparently first-order polyamorphic transition has been observed with increasing pressure at ambient temperature in a molecular glass of composition Ge(2.5)As(51.25)S(46.25) Raman spectroscopic measurements on pressure-quenched samples and in situ x-ray diffraction measurements indicate that this transition corresponds to a collapse of the ambient-pressure molecular phase to a high-pressure network phase. The high-pressure phase first appears at a pressure of approximately 8-9 GPa and the transformation becomes complete at approximately 14-15 GPa. Calorimetric measurements indicate that the low- and high-pressure phases are thermodynamically distinct and that they coexist in the transition range.     

Viscosity and glass transition temperature of hydrous float glass

Viscosity of water-bearing float glass (0.03-4.87 wt% H₂O) was measured in the temperature range of 573-1523 K and pressure range of 50-500 MPa using a parallel plate viscometer in the high viscosity range and the falling sphere method in the low viscosity range. Melt viscosity depends strongly on temperature and water content, but pressure up to 500 MPa has only minor influence. Consistent with previous studies on aluminosilicate compositions we found that the effect of dissolved water is most pronounced at low water content, but it is still noticeable at high water content. A new model for the calculation of the viscosities as a function of temperature and water content is proposed which describes the experimental data with a standard deviation of 0.22 log units. The depression of the glass transition temperature T_g by dissolved water agrees reasonably well with the prediction by the model of Deubener [J. Deubener, R. Müller, H. Behrens, G. Heide, J. Non-Cryst. Solids 330 (2003) 268]. Using water speciation measured by near-infrared spectroscopy we infer that although the effect of OH groups in reducing T_g is larger than that of H₂O molecules, the difference in the contribution of both species is smaller than predicted by Deubener et al. (2003). Compared to alkalis and alkaline earth elements the effect of protons on glass fragility is small, mainly because of the relatively low concentration of OH groups (max. 1.5 wt% water dissolved as OH) in the glasses.     

Mass spectrometry of surfactant aggregates

In contrast with the enormous amount of literature produced during many decades in the field of surfactant aggregation in liquid, liquid crystalline and solid phases, only a few investigations concerning surfactant self- assembling in the gas phase as charged aggregates have been carried out until now. This lack of interest is disappointing in view of the remarkable theoretical and practical importance of the inherent knowledge. The absence of surfactant-solvent interactions makes it easier to study the role of surfactant-surfactant forces in determining their peculiar self-assembling features as well as the ability of these assemblies to incorporate selected solubilizate molecules. Thus, the study of gas-phase surfactant and surfactant-solubilizate aggregates is a research subject which has exciting potential, including mass and energy transport in the atmosphere, origin of life and simulation of supramolecular aggregation in interstellar space. On the other hand, the structural and dynamic properties of surfactant aggregates in the gas phase could be exploited in a number of interesting applications such as atmospheric cleaning agents, transport and protection of pulmonary drugs or biomolecules and as nanoreactors for specialized chemical reactions in confined space. Spectrometric techniques, together with molecular dynamics simulations, have been the principal investigative tools in this field and appearto be particularly suited to gaining fundamental information on the structure and stability of surfactant-based supramolecular aggregates, charge state effects, entrapment of solubilizate molecules, preferential solubilization sites and chemical reactions localized in a single organized aggregate. The main aim of this review is to present the actual state of the art in this novel and exciting research field underlining the knowledge acquired up to now as well as the aspects needing a more deep understanding. Moreover, intriguing departures of the behavior of surfactant solutions under electrospray ionization conditions from that of ionic, polar and apolar analytes will be discussed.     

Zero sound in a mixture of a single-component fermion gas and a Bose-Einstein condensate

The resonant dynamics of mediated interactions supports zero sound in a cold atom degenerate mixture of a single-component fermion gas and a Bose-Einstein condensate. We characterize the onset of instability in the phase separation of an unstable mixture and we find a rich collective mode structure for stable mixtures with one undamped mode that exhibits an avoided crossing and a Landau-damped mode that terminates.