Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS

Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.     

Practical synthesis and elaboration of methyl 7-chloroindole-4-carboxylate

A synthesis of a previously unknown indole derivative is presented. The route reported herein allows for the preparation of multihundred gram quantities of material without any chromatographic purification. Conditions are presented for the Pd-catalyzed elaboration of one of the "diversity generating elements" of this important pharmacophore.     

Optical behavior of antibiofouling additives in environment‐friendly coverglass materials for bio‐sensors and solar panels

Solar panels and bio‐optical sensors play a significant and growing role in a number of applications that are of importance to many organizations. Many of these instruments require a high transmission of radiation into the device for it to work properly. A major issue faced is that harsh marine environments often aid in the growth or development of fouling on the coverglass used to protect the instruments. Over a period of time in an ocean environment, some plant or animal may attach itself to the coverglass, ultimately obscuring the glass and rendering the instrument useless. As such, an antifouling mechanism is needed for these instruments that is inexpensive, long‐lasting, and environment friendly. The approach discussed herein involves the use of known antifouling chemicals which have been incorporated into the polymer matrix. Polymethylmethacrylate (PMMA), bisphenol A polycarbonate (Bis A PC), and a co‐polyterephthalate (CPTE) were examined. The plaques are optically transparent and previous work has shown that, for most samples, the materials display a minimal decrease in mechanical behavior upon the addition of the algaecides. This paper will discuss the effects on the materials' optical properties when exposed to both harsh marine conditions as well as high intensity UV light. Specifically, the decrease in transmission of visible light was examined over a 6 month period of time. Copyright © 2008 John Wiley & Sons, Ltd.     

Die Adsorptionstheorie der geschichteten Niederschläge

Ohne Zusammenfassung     

Gold(I) and Silver(I) Complexes with Thioether Functionalized Silylamido Ligands

The thioether functionalized aminosilanes Me₂Si(NH‐C₆H₄‐2‐SR)₂ (R = Ph, Me) were lithiated with nBuLi and subsequently reacted with AgCl in the presence of PMe₃ or with [AuCl(PMe₃)]. In the case of Me₂Si(NH‐C₆H₄‐2‐SPh)₂ the dinuclear complexes [M₂{Me₂Si(NC₆H₄‐2‐SPh)₂}(PMe₃)₂] (M = Ag; Au) were isolated. The analogous reactions starting from Me₂Si(NH‐C₆H₄‐SMe)₂ afforded the dinuclear gold complex [Au₂{Me₂Si(NC₆H₄‐2‐SMe)₂}(PMe₃)₂] and the tetranuclear silver complex [Ag₄{Me₂Si(NC₆H₄‐2‐SMe)₂}₂(PMe₃)₂]. In the dinuclear compounds of the type [M₂{Me₂Si(NC₆H₄‐2‐SR)₂}(PMe₃)₂], each of the silylamide N atoms is connected to a M(PMe₃) group to give a nearly linear N–M–P arrangement with Ag–N and Au–N bonds in the range of 212.0(4)–213.3(4) pm and 205.3(3)–208.1(9) pm, respectively. [Ag₄{Me₂Si(NC₆H₄‐2‐SMe)₂}₂(PMe₃)₂] consists of a central Si₂N₄Ag₂ ring with linearly coordinated Ag atoms (Ag‐N: 223.1(4)–222.1(4) pm) and two peripheral Ag(PMe₃) units, which are connected to the amido N atoms in a chelating mode. The relatively short transannular Ag ··· Ag separation (277.6(1) pm) within the Si₂N₄Ag₂ ring hints for argentophilic interactions. The peripheral Ag atoms are three coordinated with Ag–N distances of 233.9(4)–242.8(4) pm.     

UnyLinker dimer impurity characterization and process improvement

Herein, we describe the isolation and characterization of a UnyLinker dimer which, if left uncontrolled, can become incorporated in oligonucleotide products. The dimer is formed as a result of an unusual intermolecular osmium-catalyzed etherification. We demonstrate that by simply replacing H₂O₂ as the co-oxidant with NMO, none of the UnyLinker dimer impurity is formed.     

High resolution Dopplerimetry of correlated angular and quantum state-resolved CO(2) scattering dynamics at the gas-liquid interface

Full three dimensional (3D) translational distributions for quantum state-resolved scattering dynamics at the gas-liquid interface are presented for experimental and theoretical studies of CO(2) + perfluorinated surfaces. Experimentally, high resolution absorption profiles are measured as a function of incident (θ(inc)) and scattering (θ(scat)) angles for CO(2) that has been scattered from a 300 K perfluorinated polyether surface (PFPE) with an incident energy of E(inc) = 10.6(8) kcal mol(-1). Line shape analysis of the absorption profiles reveals non-equilibrium dynamics that are characterized by trapping-desorption (TD) and impulsive scattering (IS) components, with each channel simply characterized by an effective "temperature" that compares very well with previous results from rotational state analysis [Perkins and Nesbitt, J. Phys. Chem. A, 2008, 112, 9324]. From a theoretical perspective, molecular dynamics (MD) simulations of CO(2) + fluorinated self-assembled monolayer surface (F-SAMs) yield translational probability distributions that are also compared with experimental results. Trajectories are parsed by θ(scat) and J, with the results rigorously corrected by flux-to-density transformation and providing comparisons in near quantitative agreement with experiment. 3D flux and velocity distributions obtained from MD simulations are also presented to illustrate the role of in- and out-of-plane scattering.