Possible evidence for a narrow isovectorB=2 resonance below pion production threshold

Some evidence is presented for a narrow peak at 1969±2 MeV (FWHM=9±2 MeV) in the missing mass spectrum of the³He(p, d) reaction, with 3 standard deviations. The nature of this state, the mass of which is below the NN threshold, is discussed in connection with structures found in other experiments.     

Chelate polypyridine ligand rearrangement in Au(III) complexes

The reaction of gold(III) neutral complexes AuBr(CN)₂(N–N) {N–N = 2,2′-bipyridine (bpy), 5,5′-dimethyl-2,2′-bipyridine (^Me2bpy), 1,10-phenanthroline (phen)} with a stoichiometric amount of K[AuCl₄] · 2H₂O in nitromethane at room temperature led to the formation of 1:1 electrolytes which were characterized by NMR and IR spectroscopy, conductivity measurements, elemental analyses and X-ray diffraction. Both the anions and the cations of these salts are singly charged square-planar Au(III) complexes and the cations have general formula [AuCl₂(N–N)]⁺. A hypothesis on the possible reaction mechanisms is presented to give an explanation for the formation of the reaction products.     

Angular distributions in the dimuon hadronic production at 150 GeV/c

From π^- interactions at 150 GeV/c on a heavy target, we present the final analysis of the dimuon decay angular distribution in the mass interval 4.5–8.5 GeV/c². Results are presented and discussed in various reference frames and are also given in terms of the density matrix elements. Finally the possible contribution of higher-twist effects at largex ₁ is discussed; we find that our data are not compatible with higher twist contributions as proposed by the Berger and Brodsky Model.     

Petasis three-component coupling reactions of hydrazides for the synthesis of oxadiazolones and oxazolidinones

An application of readily available hydrazides in the Petasis 3-component coupling reaction is presented. An investigation of the substrate scope was performed to establish a general, synthetically useful protocol for the formation of hydrazido alcohols, which were selectively converted to oxazolidinone and oxadiazolone ring systems through triphosgene-mediated cyclization reactions.     

Drug resistance modulation in Staphylococcus aureus, a new biological activity for mesoionic hydrochloride compounds

Two salts of the mesoionic compounds 1,4-diphenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-thiol chloride (MC-1) and 4-phenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-phenylamine chloride (MC-2) were synthesized utilizing 1,4-diphenyl-thiosemicarbazide and 5-nitro-2-furoyl chloride as starting materials. Their structures were characterized by IR, 1H-NMR, 13C-NMR and elemental analysis. These compounds were analyzed for their influence on the effectiveness of norfloxacin, tetracycline, and erythromycin (standard antibiotics) against resistant strains of Staphylococcus aureus. MC-1 and MC-2, at sub-inhibitory concentrations of 16 μg/mL, favourably modulated the antibiotic activity of tetracycline by 16- and 32-fold, respectively (MIC), and that of erythromycin by 4-fold.     

Perfluoro compounds as blood substitutes.

Inconceivable as it is, it has been proved that animals can survive after having had their blood massively or even totally replaced by emulsions of perfluorinated compounds in salines. “Bloodles” rats charged with an emulsion of perfluorotri-n-butylamine survived a five hour period in an atmosphere containing 50% oxygen and 50% carbon monoxide, i.e. in conditions where the transport of oxygen by the red cells is entirely blocked. This review discusses: (1) the experiments which have demonstrated the capability of blood substitutes based on perfluorinated compounds to sustain life; (2) the characteristics and preparation of the relevant perfluoro compounds and the production and handling of their emulsions; (3) their “physiology”, i.e. toxicity, life-span in the blood-stream, effect on the organs and their functions, and excretion properties. Obstacles remaining to be overcome in order to provide a safe blood substitute for medical practice include the availability of numerous series of well-defined pure and inert perfluorinated chemicals, the production of stable emulsions, the optimization of fluid balance, and the attainment of reasonable excretion rates. The accent is placed upon the role of the chemist in the progress of this research.     

Preparation and characterization of ruthenium(II) monophosphaferrocene complexes. Reactivity, dynamic solution behavior, and X-ray structure of [RuH(2)(eta(2)-H(2))(PCy(3))2(2-phenyl-3,4-dimethylphosphaferrocene)

The bis(dihydrogen) complex RuH(2)(H(2))(2)(PCy(3))(2) (1) reacts with 2-phenyl-3,4-dimethylphosphaferrocene (L(1)) to give RuH(2)(H(2))(PCy(3))(2)(L(1)) (2). This dihydride-dihydrogen complex has been characterized by X-ray crystallography and variable-temperature (1)H and (31)P NMR spectroscopy. The exchange between the dihydrogen ligand and the two hydrides is characterized by a DeltaG() of 46.2 kJ/mol at 263 K. H/D exchange is readily observed when heating a C(7)D(8) solution of 2 (J(H-D) = 30 Hz). The H(2) ligand in 2 can be displaced by ethylene or carbon monoxide leading to the corresponding ethylene or carbonyl complexes. The reaction of 1 with 2 equiv of 3,4-dimethylphosphaferrocene (L(2)) yields the dihydride complex RuH(2)(PCy(3))(2)(L(2))(2) (5).     

Measurement Bias on Nanoparticle Size Characterization by Asymmetric Flow Field-Flow Fractionation Using Dynamic Light-Scattering Detection

In this work, we highlight the influence of the particle–particle interaction on the retention behavior in asymmetric flow field-flow fractionation (A4F) and the misunderstanding considering the size determination by a light-scattering detector (static and dynamic light scattering) by comparing fullerene nanoparticles to similar sized polystyrene nanoparticle standards. The phenomena described here suggest that there are biases in the hydrodynamic size and diffusion determination induced by particle–particle interactions, as characterized by their virial coefficient. The dual objectives of this paper are to (1) demonstrate the uncertainties resulting from the current practice of size determination by detectors coupled to an A4F system and (2) initiate a discussion of the effects of particle–particle interactions using fullerene nanoparticles on their characterization as well as their origins. The results presented here clearly illustrate that the simple diffusion coefficient equation that is generally used to calculate the hydrodynamic size of nanoparticles (NPs) cannot be considered for whole fractograms according to their size distribution. We tried to identify particle interactions that appear during fractionation and demonstrated using the fully developed diffusion coefficient equation. We postulate that the observed interaction-dependent retention behavior may be attributed to differences in the virial coefficient between NPs and between NPs and the accumulation wall (membrane surface) without quantifying it. We hope that our results will stimulate discussion and a reassessment of the size determination procedure by A4F-LS to more fully account for all the influential material parameters that are relevant to the fractionation of nanoscale particles by A4F.     

On the ultrafast infrared spectroscopy of anion hydration shell hydrogen bond dynamics

Molecular Dynamics simulations are used to examine the title issue for the I-/HOD/D2O solution system in connection with recent ultrafast infrared spectroscopic experiments. It is argued that the long "modulation time" associated with the spectral diffusion of the OH frequency, extracted in these experiments, should be interpreted as reflecting the escape time of an HOD from the first hydration shell of the I- ion, i.e., the residence time of an HOD in this solvation shell. Shorter time features related to the oscillation of the OH ...I- hydrogen bond and the breaking and making of this bond are also discussed.     

Diamondoid Nanostructures as sp3‐Carbon‐Based Gas Sensors

Diamondoids, sp³‐hybridized nanometer‐sized diamond‐like hydrocarbons (nanodiamonds), difunctionalized with hydroxy and primary phosphine oxide groups, enable the assembly of the first sp³‐C‐based chemical sensors by vapor deposition. Both pristine nanodiamonds and palladium nanolayered composites can be used to detect toxic NO₂ and NH₃ gases. This carbon‐based gas sensor technology allows reversible NO₂ detection down to 50 ppb and NH₃ detection at 25–100 ppm concentration with fast response and recovery processes at 100 °C. Reversible gas adsorption and detection is compatible with 50 % humidity conditions. Semiconducting p‐type sensing properties are achieved from devices based on primary phosphine–diamantanol, in which high specific area (ca. 140 m² g^?1) and channel nanoporosity derive from H‐bonding.