The ring-opening polymerization (ROP) of L,L-lactide (L-LA) has been studied in bulk using alcohol (either methanol or benzyl alcohol) and 1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene carbene, 1, respectively as initiator and non-organometallic catalyst, over a range of temperature and alcohol-to-1 molar ratios. Although 1 is known to perfectly control the polymerization of L-LA in so...

Controlled growth of ZnSe and ZnCdSe nanowires is demonstrated by molecular beam epitaxy using Au or Ag catalyst films in the temperature range 400–550 ◦C. The highest density of small-diameter (10 nm), highly-crystalline ZnSe nanowires is achieved by using Au at 400 ◦C. Direct growth onto transmission electron microscope grids clearly indicates a tip-growth regime. Pre-patterning of the cataly...

A series of Cr(III) complexes based on quinoline-cyclopentadienyl ligands with additional hemilabile side arms were prepared and used as single-site catalyst precursors for ethylene polymerization. The additional donor functions interact with the metal centers only after activation with the co-catalyst. Evidence for this comes from DFT-calculations and from the differing behavior of the complex...

Energy conversion cycles are aimed at driving unfavorable, small-molecule activation reactions with a photon harnessed directly by a transition-metal catalyst or indirectly by a transition-metal catalyst at the surface of a photovoltaic cell. The construction of such cycles confronts daunting challenges because they rely on chemical transformations not understood at the most basic levels. These...

Oligonucleotides synthesized on a montmorillonite catalyst were analyzed directly. By mixing the catalyst with a matrix (2,4,6-trihydroxyacetophenone or 6-aza-2-thiothymine) and dibasic ammonium citrate, higher molecular weight products were detected compared with "classical" methods such as gel electrophoresis and HPLC with UV as a detector. The oligomers (30-mers and higher) were detected by ...

A parametrized mesoscale model for the early stage growth of isolated single or multiwall carbon nanotubes (CNTs) has been developed in order to investigate the effects of metal catalyst particle size and composition on CNT growth mechanism during synthesis via a substrate-supported, catalytic chemical vapor deposition process. The model is based on a coarse-grained graphene sheet, represented ...

Vanadium-modified (SiO2/MgO/MgCl2)•TiClx Ziegler-Natta catalysts were prepared through co-impregnation of water-soluble magnesium and vanadium salts under different pH values. Several key factors such as pH value of co-impregnation solution during catalyst preparation, catalyst performances including catalytic activity, ethylene/1-hexene copolymerization and hydrogen response were investigated....

Chromium-vanadium (Cr-V) bimetallic catalysts are prepared by the introduction of vanadium into the Phillips catalyst which is one of the most significant industrial ethylene polymerization catalysts for tuning the Phillips catalyst performances and improving polyethylene properties. In the present work, titanium species were introduced into the fluorine-modified chromium-vanadium bimetallic ca...

Photocatalytic Water Oxidation The art representing article number 2203102 by Nathan I. Hammer, Jared H. Delcamp, and co-workers depicts the organic molecular photosensitizer QL11-OEG being irradiated with visible light under water. strong photooxidant is in a 16 microsecond long-lived excited state near ruthenium-based water oxidation catalyst. oxidizing catalyst to drive conversion of molecul...

Catalytic nucleation of carbon nanotubes (CNTs) remains a challenge for the theory: Which factors and forces decide if the gathering sp(2)-network of atoms will adhere to the catalyst particle and fully cover it or the graphitic cap will liberate itself to extend into a hollow filament? This intimate mechanism cannot be seen in experiment, yet it can be investigated through comprehensive molecu...