φ meson production fromp\bar p collisions at\sqrt s = 1.8 TeV

Fermilab experiment E735 located at the CO intersection region of the $\sqrt s = 1.8$ TeV $p\bar p$ collider analysed over 900 Φ→K ⁺ K ^? events. Measured were the transverse momentum spectrum, the correlation between the average transverse momentum <pt> and the charged particle multiphcityN _c , as well as the probability of Φ production per charged track,N _Φ /N _c , versusN _c . We have also made an estinate of the total inclusive cross section for Φ mesons, $\sigma (p\bar p \to \phi X) = 7.3 \pm 2.2 mb$ .     

Kinetics of Nitroxide Mediated Radical Polymerization of Styrene with Unimolecular Initiators

Summary: This study examined the kinetics of nitroxide-mediated radical polymerization of styrene with unimolecular (alkoxyamine) initiators. Control of polymerization rate and polymer molecular weight in unimolecular nitroxide-mediated radical polymerization was studied by looking at the effects of the three main factors: initiator concentration, temperature, and initiator molecular weight on polymerization rate, molecular weight and polydispersity. In addition, the behavior of the unimolecular initiating systems was compared to that of the corresponding bimolecular system. The effective TEMPO concentration and degree of self-initiation of styrene were proved to be significant in dictating magnitudes of molecular weight averages and widths of molecular weight distribution.     

Minimally adhesive polymer surfaces prepared from star oligosiloxanes and star oligofluorosiloxanes

The effects of the surface energy, storage modulus (G′), and glass‐transition temperature (T_g) on the biofouling behavior of siloxane and fluorosiloxane polymer surfaces (films) were studied. Irregular Si? H‐terminated tetrabranched star oligosiloxanes and star oligofluorosiloxanes were prepared by the acid‐catalyzed equilibration of octamethylcyclotetrasiloxane or 1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane with tetrakis(dimethylsiloxy)silane, respectively. Terminal epoxy groups were introduced via Pt‐catalyzed hydrosilylation with allyl glycidyl ether to yield compounds that were subsequently crosslinked with α,ω‐bis(3‐aminopropyl)poly(dimethylsiloxane). The resulting films were characterized by goniometry, dynamic mechanical thermal analysis, and thermogravimetric analysis. The foul‐release behavior was studied by the measurement of how strongly sporelings (young plants) of the green seaweed Ulva adhered. The corrosion protection of aluminum was evaluated by electrochemical impedance spectroscopy. Fluorosiloxane films displayed higher G′ and T_g values, decreased contact angles (with water), and more effectively released Ulva sporelings in comparison with siloxane films. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2551–2566, 2006     

Next-Generation NAMPT Inhibitors Identified by Sequential High-Throughput Phenotypic Chemical and Functional Genomic Screens

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Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

Little is known about the pathway of room‐temperature formation of ternary CdTeSe magic‐size clusters (MSCs) obtained by mixing binary CdTe and CdSe induction period samples containing binary precursor compounds (PCs) of MSCs, monomers (Ms), and fragments (Fs). Also, unestablished are dispersion effects that occur when as‐mixed samples (without incubation) are placed in toluene (Tol) and octylamine (OTA) mixtures. The resulting ternary MSCs, exhibiting a sharp optical absorption peak at 399 nm, are labelled CdTeSe MSC‐399, and their PCs are referred to as CdTeSe PC‐399. When the amount of OTA is relatively small, single‐ensemble MSC‐399 evolved without either binary CdTe or CdSe MSCs. When the OTA amount is relatively large, CdTe MSC‐371 appeared initially and then disappeared, while single‐ensemble MSC‐399 developed more deliberately. The larger the OTA amount, the more slowly these changes proceeded. The substitution reaction of CdTe PC + CdSe M/F?CdTeSe PC‐399 + CdTe M/F is proposed to be rate‐determining for the MSC‐399 formation in a Tol and OTA mixture. This study provides further understanding of the transformation pathway between MSCs.     

Laser-induced breakdown spectroscopy analysis of complex silicate minerals—beryl

Beryl (Be₃Al₂Si₆O₁₈) is a chemically complex and highly compositionally variable gem-forming mineral found in a variety of geologic settings worldwide. A methodology and analytical protocol were developed for the analysis of beryl by laser-induced breakdown spectroscopy (LIBS) that minimizes the coefficient of variance for multiple analyses of the same specimen. The parameters considered were laser energy/pulse, time delay and crystallographic orientation. Optimal analytical conditions are a laser energy/pulse of 102 mJ and a time delay of 2 μs. Beryl compositions measured parallel and perpendicular to the c axis were identical within analytical error. LIBS analysis of 96 beryls from 16 countries (Afghanistan, Brazil, Canada, China, Colombia, India, Ireland, Italy, Madagascar, Mexico, Mozambique, Namibia, Norway, Russia, Tanzania and United States), Antarctica, and ten US states (AZ, CA, CO, CT, ID, ME, NC, NH, NM and UT) were undertaken to determine whether or not LIBS analysis can be used to determine the provenance of gem beryl.     

Performance and pathways of electrochemical cyclohexane oxidation

Falling costs of electricity from renewable and non-renewable sources have motivated interest in electrochemical production of chemicals and fuels. Among commodity chemicals, the production of KA oil (cyclohexanol and cyclohexanone) from cyclohexane is attractive as selective alkane oxidation remains a major industrial challenge. Although this reaction has been demonstrated in the literature, its fundamental chemistry remains poorly understood. This review identifies possible pathways for the reaction mechanism, their experimental support, and remaining critical gaps in molecular understanding of electrochemical cyclohexane oxidation to KA oil.     

A Xanthene-Based Mono-Anionic PON Ligand: Exploiting a Bulky,Electronically Unsymmetrical Donor in Main Group Chemistry

The synthesis of a novel mono-anionic phosphino-amide ligand based on a xanthene backbone is reported, togetherr with the corresponding Ga^I complex, (PON)Ga (PON = 4-(di(2,4,6-trimethylphenyl)phosphino)-5-(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene). The solid-state structure of (PON)Ga (obtained from X-ray crystallography) reveals very weak O⋅⋅⋅Ga and P⋅⋅⋅Ga interactions, consistent with a R₂NGa fragment which closely resembles those found in one-coordinate amidogallium systems. Strong N-to-Ga π donation from the amido substituent is reflected in a very short N−Ga distance (1.961(2) Å), while the P⋅⋅⋅Ga contact (3.076(1) Å) is well outside the sum of the respective covalent radii. While the donor properties of the PON ligand towards Ga^I are highly unsymmetrical, oxidation to Ga^III leads to much stronger coordination of the pendant phosphine as shown by P−Ga distances which are up to 20 % shorter. From a steric perspective, the PON ligand is shown to be significantly bulkier than related β-diketiminate systems, a finding consistent with reactions of (PON)Ga towards O-atom sources that proceed without oligomerization. Despite this, the enhanced P-donor properties brought about by oxidation at gallium are not sufficient to quench the reactivity of the highly polar Ga−O unit. Instead, intramolecular benzylic C−H activation is observed across the Ga−O bond of a transient gallanone intermediate.     

A tunable diode laser system for the remote sensing of on-road vehicle emissions

2 O, and NO₂ emissions have been measured with this instrument. The system is also capable of measuring CO, NH₃, H₂CO, CH₃OH, and other small molecules in vehicle exhaust. Received: 18 May 1998/Revised version: 1 July 1998     

Cranberry proanthocyanidins mediate growth arrest of lung cancer cells through modulation of gene expression and rapid induction of apoptosis

Cranberries are rich in bioactive constituents purported to enhance immune function, improve urinary tract health, reduce cardiovascular disease and more recently, inhibit cancer in preclinical models. However, identification of the cranberry constituents with the strongest cancer inhibitory potential and the mechanism associated with cancer inhibition by cranberries remains to be elucidated. This study investigated the ability of a proanthocyanidin rich cranberry fraction (PAC) to alter gene expression, induce apoptosis and impact the cell cycle machinery of human NCI-H460 lung cancer cells. Lung cancer is the leading cause of cancer-related deaths in the United States and five year survival rates remain poor at 16%. Thus, assessing potential inhibitors of lung cancer-linked signaling pathways is an active area of investigation.