Non conventional syntheses of heterocyclic compounds. 2. Synthesis of 1H-4,5-dihydro-1,3,4-benzotriazepine derivatives

Arylazoanils carrying aromatic methyl or ethyl groups in the position ortho to the imine function thermally cyclize to give 1H-4,5-dihydro-1,3,4-benzotriazepine derivatives in fairly good yields. A study of the effect of the substituents on both the aryl rings is reported. The reaction is interpreted as an internal oxo-reduction process.     

Effects of modifiers on the chromatographic behaviour of propafenone and its major metabolites

Summary Propafenone (PPF) is a new antiarrhythmic agent with structural features in common with the class of beta-blocking drugs (phenoxypropanolamines). Because of its high lipophilicity, the drug is strongly retained in reverse phase (RP) columns and simultaneous determination with the main polar metabolites 5-OH-PPF, N-depropyl-PPF and 5-OH-4-methoxy-PPF requires long run times (up to 50 min.) Oxidative metabolism in vivo often produces derivatives whose higher polarity results from the addition of a polar group and/or the subtraction of an apolar one. These metabolites show similar chromatographic behaviour in RP mode and the trade-off between their separation and the sensitivity of the parent compound must be investigated. In an effort to shorten the run time we examined the retention of these early eluting substances as a function of different amine additives, pH and organic content in mobile phase using C8 and C-18 columns from different sources, previously characterized for their free silanophilic and hydrophobic activities. Under optimal conditions the run time was reduced to 14 minutes and an application of the optimized method to the determination in plasma samples of the drug and its main metabolites after chronic therapy with PPF is presented. To investigate possible coelution of other yet undiscovered metabolites which could accumulate in some patients under chronic treatment, the analysis was carried out using an electrochemical detection in parallel with the UV. Agreement was found between the two detection procedures and suggest no interference.     

Biosensor immunoassays for the detection of bisphenol A

Bisphenol A (BPA) is a xenoestrogen found in the environment, in consequence, for the biosensor detection of BPA we raised antibodies (polyclonal (PAbs) and monoclonal (MAbs)) against a structural analogue of BPA, 4,4 bis-(4-hydroxyphenyl) valeric acid (BVA). The kinetics of the MAb-BPA interaction were evaluated and the MAb providing the highest affinity was directly immobilized onto the sensor chip surface to evaluate a direct assay. Afterwards, the performance of the MAbs and the PAbs was compared in an inhibition assay using a BVA-coated chip.The highest sensitivity (limit of detection (LOD) of 0.4 μg L⁻¹) was obtained with MAb 12 in the direct assay. However, the inhibition assay was the most robust and the PAbs showed the highest sensitivity (LOD of 0.5-1 μg L⁻¹). The antibodies were specific for BVA and BPA as only minor cross-reactivities were found toward structurally related compounds or other endocrine disruptors. In the inhibition assay (with a run time of 6 min), water samples spiked with BPA at different levels (0.5-50 μg L⁻¹) resulted in recoveries varying between 68% and 121%. The sensitivity of the inhibition assay could be improved 40 times (LOD of 0.03 μg L⁻¹ with the Mab 12-based assay) using solid phase extraction (SPE).     

A topological expansion for high-energy hadronic collisions: (I). General properties and connection with the reggeon calculus

In this and in a companion paper a “topological expansion” for high-energy hadronic processes is proposed and discussed. In this first paper the general properties of the expansion and its connection with Gribov's reggeon calculus are presented. The topological expansion is first defined mathematically for a large class of theories and is shown to be equivalent to a “large N expansion” in some theories which include planar dual models and non-Abelian gauge theories. Next, the definition of the bare parameters is given in terms of graphs on a sphere. The bare pomeron pole and its couplings are thus introduced. The (inclusive) form of s-channel unitarity and its consequences fo the above couplings are recalled. It is then shown how the expansion in the number of “handles” of the graph can be related to Gribov's reggeon calculus and how, with the aid of discontinuity equations in the J-plane, scaling solutions can be obtained and critical indices can be computed to yield known results. Our main new results, including the study of s-channel discontinuities and of positivity constraints as well as the definition of a new fireball expansion, and the discussion of the relevance of this theory at finite (present) energies are presented in the second paper.     

ALS User Meeting Highlights Accomplishments and Challenges

The 2015 User Meeting brought together 405 ALS users from around the world, many of whom shared insights and sparked discussion with presentations of their ALS research highlights. UEC Chair Chris Cappa launched the meeting with a welcome, followed by another from Berkeley Lab Director Paul Alivisatos. Speaking of the vitality and community that's key to the ALS, Alivisatos also touched on how the ALS could be utilized and optimized with a high-coherence upgrade. ALS Director Roger Falcone outlined short-term and long-term planning for the ALS, with ongoing efforts to develop new beamlines and capabilities within the next three years and beyond.     

An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy

X-ray diffraction microscopy (XDM) is a new form of X-ray imaging that is being practiced at several third-generation synchrotron-radiation X-ray facilities. Nine years have elapsed since the technique was first introduced and it has made rapid progress in demonstrating high-resolution three-dimensional imaging and promises few-nanometer resolution with much larger samples than can be imaged in the transmission electron microscope. Both life- and materials-science applications of XDM are intended, and it is expected that the principal limitation to resolution will be radiation damage for life science and the coherent power of available X-ray sources for material science. In this paper we address the question of the role of radiation damage. We use a statistical analysis based on the so-called “dose fractionation theorem” of Hegerl and Hoppe to calculate the dose needed to make an image of a single life-science sample by XDM with a given resolution. We find that the needed dose scales with the inverse fourth power of the resolution and present experimental evidence to support this finding. To determine the maximum tolerable dose we have assembled a number of data taken from the literature plus some measurements of our own which cover ranges of resolution that are not well covered otherwise. The conclusion of this study is that, based on the natural contrast between protein and water and “Rose-criterion” image quality, one should be able to image a frozen-hydrated biological sample using XDM at a resolution of about 10 nm.     

A New Synthesis of 3-Vinylindoles

A new synthesis of substituted 3-vinylindoles from 3-[(1-hydroxy-2-substituted)ethylidene]indol-2(3H)-ones is reported.     

Order and membrane stability from magnetic resonance measurements: an application of statistical thermodynamics

Summary This paper compares different approaches, reported in the literature, for obtaining thermodynamic statistical information from ESR and NMR measurements on the conformations of lipid bilayers. A statistical approach recently proposed by the authors has been employed to reexamine several literature values of order parameters and to calculate Helmholtz free energy and entropy. This approach was applied to eggphosphatidylcholine, cerebroside and gangliosoyds, spin labelled at different acyl chain positions, and to bilayered membranes containing phosphatidylcholine and different gangliosides (GM1, GD1a and GT1b) at increasing glycolipid mole percent. The variation of the stability of the membrane with the peroxidation is also reexamined at different intramembrane locations by various probes. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Differential photoelectron holography: a new approach for three-dimensional atomic imaging

We propose differential holography as a method to overcome the long-standing forward-scattering problem in photoelectron holography and related techniques for the three-dimensional imaging of atoms. Atomic images reconstructed from experimental and theoretical Cu 3p holograms from Cu(001) demonstrate that this method suppresses strong forward-scattering effects so as to yield more accurate three-dimensional images of side- and backscattering atoms.