Phase behavior and preparation of mesoporous silica in aqueous mixtures of fluorinated surfactant and hydrophobic fluorinated polymer

The phase behavior and formation of self-assemblies in the ternary water/fluorinated surfactant (C(8)F(17)EO(10))/hydrophobic fluorinated polymer (C(3)F(6)O)(n)COOH system and the application of those assemblies in the preparation of mesostructured silica have been investigated by means of phase study, small angle X-ray scattering, and rheology. Hexagonal (H(1)), bicontinuous cubic (V(1)) with Ia3d symmetry, and polymer rich lamellar (L(alpha)(')) are observed in the ternary diagram. C(8)F(17)EO(10) molecules are dissolved in polymer rich aggregates, whereas (C(3)F(6)O)(n)COOH molecules are practically insoluble in the surfactant lamellar phase due to packing restrictions. Hence, two types of lamellar phases exist: one with surfactant rich (L(alpha)) and the other with polymer rich (L(alpha)(')) in the water/C(8)F(17)EO(10)/(C(3)F(6)O)(n)COOH system. As suggested by rheological measurements, worm-like micelles are present in C(8)F(17)EO(10) aqueous solutions but a rod-sphere transition takes place by solubilization of (C(3)F(6)O)(n)COOH. C(8)F(17)EO(10) acts as a structure directing agent for the preparation of hexagonal mesoporous silica by the precipitation method. The addition of (C(3)F(6)O)(n)COOH induces the formation of larger but disordered pores.     

A general framework for non-Boltzmann Monte Carlo sampling

Non-Boltzmann sampling (NBS) methods have been extensively employed in recent years, mainly due to their ability to enhance ergodicity in simulations of complex systems. In addition, they make possible reliable computation of equilibrium properties (ensemble averages, free-energy differences, and potentials of mean force) over continuous ranges of thermodynamic conditions. In this work, we put forward a general and systematic framework for NBS methods that allows a single set of equations and procedures to be applied to diverse systems. Moreover, we show how to exploit simulation data most effectively by obtaining continuous profiles of any mechanical properties, including structural quantities not directly related to the ensemble parameters. Finally, we demonstrate the usefulness of the developed formulation by applying it to spin systems, Lennard-Jones fluids, and a model protein molecule (both in isolation and in the proximity of a flat wall).     

Synthesis and characterization of boronates derived from non-symmetric amino-bis-phenols

The condensation of 2-[[(2-hydroxyphenyl)amino]methyl]-phenols (1a-1e) with different arylboronic acids led to 12 new monomeric boronates of the type 2-aryl-dibenzo[d,h]-6-aza-1,3-dioxa-2-boracyclononene (2a-2l). The boronates were characterized by ¹H-, ¹³C-, ¹¹B- and 2D-NMR experiments, FT infrared, mass spectra and elemental analyses. The stereochemistry of the H-N → B-Ph fusion is always cis, as established through the NMR spectra, as well as the X-ray structures of four boronates (2a, 2e, 2f and 2l). Hydrogen bonds between the amine proton and the oxygen ester of the five- membered ring are present in three X-ray structures (2a, 2e and 2f), while the supramolecular structure in the derivative possessing a primary amine (2l) is built up through the protons present in this moiety instead of the proton from the H-N → B-Ph fragment.     

Identification of phospholipid species affected by miltefosine action in <Emphasis Type="Italic">Leishmania donovani</Emphasis> cultures using LC-ELSD,LC-ESI/MS,and multivariate data analysis

Leishmaniasis is a widespread parasitic disease principally treated by intravenous drugs. Hexadecylphosphocholine (miltefosine) has recently proved its efficacy by oral route. Although its mechanism of action has been investigated, and principally relies on perturbations of the metabolism of lipids and especially phospholipids, further studies need to be conducted to detect precisely which metabolic pathways are impacted. For this purpose, the present work proposes a complete lipidomic study focused on membrane phospholipids of clones of Leishmania donovani non-treated (NT), treated (T) and resistant (R) to miltefosine. Firstly, a separation of phospholipids in normal phase high-performance liquid chromatography (NP-HPLC) was coupled to a mass spectrometer (MS) equipped with an electrospray (ESI) ion source, and response was compared to evaporative light scattering detection (ELSD). Secondly, a quantification of phospholipid classes was performed using NP-HPLC/ESI/MS on NT, T and R clones of L. donovani. Thirdly, full-scan acquisitions of analyzed samples were compared using orthogonal signal correction-partial least square-discriminant analysis (OSC-PLS-DA) to highlight phospholipid molecular species of interest between the three types of clones. Structural determination of the most relevant species has finally been performed using tandem mass spectrometry. A first hypothesis on the effect of miltefosine on lipid metabolic pathways is then proposed.     

Measurement of the top quark pair production cross section in pp collisions at s=7TeV in dilepton final states with ATLAS

A measurement of the production cross section of top quark pairs ($t\overline{t}$) in proton–proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the Large Hadron Collider is reported. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. Using a data sample corresponding to an integrated luminosity of $35{\mathrm{pb}}^{?1}$, a $t\overline{t}$ production cross section ${\sigma }_{t\overline{t}}=177\pm 20(\text{stat.})\pm 14(\text{syst.})\pm 7(\text{lum.})\text{pb}$ is measured for an assumed top quark mass of $m_t=172.5\text{GeV}$. A second measurement requiring at least one jet identified as coming from a b quark yields a comparable result, demonstrating that the dilepton final states are consistent with being accompanied by b-quark jets. These measurements are in good agreement with Standard Model predictions.     

Determination of contact angles, silane coverage, and hydrophobicity heterogeneity of methylated quartz surfaces using ToF-SIMS

Methylated quartz surfaces are extensively used in colloid science for wettability studies and the control and impact of hydrophobicity in key physicochemical processes. In this study, time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to correlate the surface chemistry of trimethylchlorosilane-methylated quartz surfaces with the contact angle. Models have been developed for the calculation of both advancing and receding contact angles based on measurements of the ToF-SIMS signals for SiC(3)H(9)(+) (TMCS) and Si(+) (quartz). These models enable the contact angle across surfaces and, more importantly, that of individual particles to be determined on a micrometer scale. Distributions of contact angles in large ensembles of particles, therefore, can now be determined. In addition, from the ToF-SIMS analysis, the surface coverage of the methylated species can be quantitatively determined, in line with the Cassie equation. Moreover, advancing and receding contact angle maps can be calculated from ToF-SIMS images, and hence the variation in microscopic hydrophobicity (e.g., at the particle level) can be extracted directly from the images.     

Plants as sources of new antimicrobials and resistance-modifying agents

Covering: up to November 2011Infections caused by multidrug-resistant bacteria are an increasing problem due to the emergence and propagation of microbial drug resistance and the lack of development of new antimicrobials. Traditional methods of antibiotic discovery have failed to keep pace with the evolution of resistance. Therefore, new strategies to control bacterial infections are highly desirable. Plant secondary metabolites (phytochemicals) have already demonstrated their potential as antibacterials when used alone and as synergists or potentiators of other antibacterial agents. The use of phytochemical products and plant extracts as resistance-modifying agents (RMAs) represents an increasingly active research topic. Phytochemicals frequently act through different mechanisms than conventional antibiotics and could, therefore be of use in the treatment of resistant bacteria. The therapeutic utility of these products, however, remains to be clinically proven. The aim of this article is to review the advances in in vitro and in vivo studies on the potential chemotherapeutic value of phytochemical products and plant extracts as RMAs to restore the efficacy of antibiotics against resistant pathogenic bacteria. The mode of action of RMAs on the potentiation of antibiotics is also described.     

Differentiation of aminomethyl corrole isomers by mass spectrometry

Two new isomeric aminomethyl corrole derivatives of [5,10,15-tris(pentafluorophenyl)corrolato]gallium(III) were synthesized with pyridine (py) molecules as axial ligands. When investigated by electrospray ionization mass spectrometry, in the positive and the negative ion modes, these compounds showed an unusual gas-phase behavior that could be used for their differentiation. In the positive ion mode, the differentiation was achieved through the formation of diagnostic fragment ions formed from [M-py?+?H](+) precursors, by (CH(3) )(2) NH and HF losses. An unusual addition of water to the main fragment ions provides an alternative route for isomer identification. Semi-empirical calculations were performed to elucidate the structures and stabilities of the main ionic species formed in the positive ion mode. In the negative ion mode isomer discrimination is accomplished via the fragmentation of the methoxide adduct ions [M-py?+?CH(3) O](-) through (CH(3) )(2) N(.) and HF losses.     

Search for the standard model Higgs boson in the diphoton decay channel with 4.9 fb(-1) of pp collision data at √s=7 TeV with ATLAS

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9 fb(-1) collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7 TeV. In the diphoton mass range 110-150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110-150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113-115 GeV and 134.5-136 GeV.