Abstract A common way to convert ethanol into chemicals is by upgrading it over oxide catalysts with basic features; this method makes possible obtain important such as 1‐butanol (Guerbet reaction) and 1,3‐butadiene (Lebedev reaction). Despite their long history in chemistry, the details of close inter‐relationship these reactions have yet be discussed properly. Our present study focuses on reactivity tests, situ diffuse reflectance infrared Fourier transform spectroscopy, MS analysis,...

The photochemistry of some fluorinated 7-amino-4-quinolone-3-carboxylic acids used in therapy as antibacterials and known to be phototoxic has been investigated water. All them undergo heterolytic defluorination, this appears a path for the generation aryl cations solution. 6-Fluoro derivatives such norfloxacin (Phi(dec) = 0.06) enoxacin 0.13) give corresponding phenols. Insertion an electron-donating substituent makes defluorination inefficient; thus, ofloxacin, 8-alkoxy derivative, is...

The synthesis of novel star-like heteroarms polymers A(BC)n containing m-PEG (block A), methylmethacrylate (MMA), and nonquaternized 2-(dimethylamino)ethyl methacrylate (DMAEMA) (blocks BC) is here reported. We demonstrated that copolymer films with comparable amounts DMAEMA have antimicrobial properties strongly depending on the topological structure (i.e., number arms) composing copolymers. interpret highest activity A(BC)2 respect to A(BC)4 linear copolymers (respectively, ≥ > A(BC)) as...

In this work, we systematically investigate the impact of counterion size on behavior star-shaped strong polyelectrolytes in dilute aqueous solutions using Langevin simulations and a primitive model electrolytes. Varying both diameter number arms polyelectrolyte, demonstrated that characteristics significantly polyelectrolyte conformations counterions absorption. Counterions dynamics is also affected, most interesting aspect being presence fraction mobile ions slowly diffusing, compared to...

The stability of the ground and excited states Positronium–atom complexes [A, Ps], Ps =[e+,e−], has been explored for A=Li, B, C, O, F using variational diffusion Monte Carlo techniques. From numerical results our simulations it turns out that state [Li, Ps]2S, [C, Ps]3S, [O, Ps]1P, [F, Ps]2S is stable against break up in two neutral fragments A Ps, while [B, Ps]2P an energy above same dissociation threshold. As to states, only possible candidate, Ps]2P, a total statistically equal lower...

1,2,4,5-Benzenetetracarbonitrile (TCB) is irradiated in the presence of adamantane (1) and some its derivatives. The singlet excited state TCB a strong oxidant, there various evidence, including time-resolved spectroscopy, to prove that SET from alkane TCB1* takes place yields corresponding radical ions. cation deprotonates bridgehead position, resulting couples with TCB-•. Deprotonation via occurs number substituted adamantanes remains exclusive or predominating reaction also derivatives...

Equilibrium geometries, interaction energies, and harmonic frequencies of (NH3)n isomers (n = 2−5) have been computed using correlated calculations (MP2) in conjunction with Dunning's aug-cc-pVXZ (X D, T, Q) basis sets the Counterpoise procedure. Whenever available, literature values for binding energy geometry dimers trimers agree well our data. Low lying (NH3)4 (NH3)5 found to similar energies (roughly 16 20 kcal/mol tetramer pentamer, respectively), perhaps suggesting presence a very...

In this study, we use Escherichia coli as a model to investigate the antimicrobial mechanism of film made copolymer based on monomethylether poly(ethylene glycol), methyl methacrylate, and 2-dimethyl(aminoethyl) whose surface is active towards Gram-negative Gram-positive bacteria. The polymer contains not quaternized amino groups that can generate charged by protonation when in contact with water. For purpose, adopted dual strategy analysis cell damage caused evaluation response toxic...

Irradiation of the 6,8-difluoroquinolone antibiotic lomefloxacin causes selective heterolytic defluorination from position 8 and leads to products rationalized as arising cation either via nucleophile addition or intramolecular carbene C–H insertion hydrogen transfer.

The stability of the ground-state positron-polar molecule complexes [M,e+] has been explored for M=LiH,HF,H2O,BeO,LiF using variational and diffusion Monte Carlo techniques. Our simulations show that [LiH,e+]2,1Σ+, [BeO,e+]2,1Σ+, [LiF,e+]2,1Σ+ is stable against dissociation either in two fragments M e+ or other M+ Ps=[e+,e−], while [H2O,e+]2,1A1, [HF,e+]2,1Σ+ an energy equal to threshold, e+. We also compare predicted vertical positron affinity (PA) with high quality electron (EA) discuss...

The family of four-particle systems (${\mathrm{M}}^{+}$${\mathrm{m}}^{+}$${\mathrm{M}}^{\mathrm{\ensuremath{-}}}$${\mathrm{m}}^{\mathrm{\ensuremath{-}}}$) has been studied by means Monte Carlo techniques. Nonadiabatic explicitly correlated wave functions for different values the mass ratio M/m have obtained using a variational optimization method. These used in diffusion simulations to compute exact ground-state energies. Our results enlarge stability range these and similar less symmetric...

The energy variance optimization algorithm over a fixed ensemble of configurations in variational Monte Carlo is formally identical to problem fitting data: we reexamine it from statistical maximum-likelihood point view. We detect the origin convergence that often encountered practice and propose an alternative procedure for trial wave functions quantum Carlo. successfully test this proposal by optimizing function Helium trimer.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron transfer photoinduced cleavage of acetals. A mild preparation alkyl radicalsM. Mella, E. Fasani, and A. AlbiniCite this: J. Org. Chem. 1992, 57, 11, 3051–3057Publication Date (Print):May 1, 1992Publication History Published online1 May 2002Published inissue 1 1992https://pubs.acs.org/doi/10.1021/jo00037a020https://doi.org/10.1021/jo00037a020research-articleACS PublicationsRequest reuse permissionsArticle Views781Altmetric-Citations41LEARN...

Whereas most of the phenomena associated with superfluidity have been observed in finite-size helium systems, nucleation quantized vortices has proven elusive. Here we show using time-dependent density functional simulations that solvation a Ba+ ion created by photoionization neutral Ba at surface 4He nanodroplet leads to ring vortex. The vortex is nucleated on 10 ps timescale equator solid-like structure forms around ion. process expected be quite general and very efficient under standard...

For weak polyelectrolytes, the interplay between pH, solvent properties, and polymer structure affects amount of charges, their distribution, hence conformations via Coloumb repulsion. Attractive interactions can also develop charged neutral sites counteracting expected Coulomb-induced expansion. To gauge how such competition polyelectrolyte ionization, titration a single chain, isolated or close to sphere, mimicked with novel many-body potential model is simulated Monte Carlo. Apart from...

Intrinsic antimicrobial thermoplastic A(BC) n copolymers ( = 1, 2, 4), where A was poly(ethylene glycol) (PEG), BC a random chain of methylmethacrylate (MMA), and alkyl‐aminoethyl methacrylate (AAEMA), were synthesized the activity hemolyticity evaluated on plaques obtained by casting as function architecture, N‐substituent groups AAEMAs (methyl, ethyl, isopropyl, tert ‐butyl groups) hydrophobic/charge density balance. Antimicrobial effectiveness efficiency is controlled surface charge...

Iodopyridinium-based tripodal receptors strongly bind anionic species in their bowl-shaped cavity through the synergistic effect of hydrogen- and halogen-bonding interactions.

The study of the energetics and structure small protonated water clusters (H2O)nH+ (n=1–5) has been carried out employing OSS3 potential energy surface developed by Ojamae, Singer, Shavitt [J. Chem. Phys. 109, 5547 (1998)]. By comparing it with accurate ab initio MP2 calculations for (H2O)nH+, this all-atom is also shown to reproduce quantitatively geometry relative neutral containing up five molecules. To correct total binding vibrational motion, zero point calculated means harmonic...

In order to overcome the difficulty of optimizing molecular geometry using quantum Monte Carlo methods, we introduce various approximations exact force expectation value. We follow Pulay’s suggestion [Mol. Phys. 17, 153 (1969)] correct Hellmann–Feynman estimator by introducing contributions due changes in wave function with respect nuclear positions. When used conjunction energy-optimized explicitly correlated trial functions for H2 and LiH, these appear yield accurate forces both...

The aim of this study was to develop a methodology for the in vitro expansion skeletal-muscle precursor cells (SMPC) three-dimensional (3D) environment order fabricate cellularized artificial graft characterized by high density viable and uniform cell distribution over entire 3D domain. Cell seeding culture within porous scaffolds conventional static techniques can lead only on scaffold surface, whereas dynamic systems have potential allowing growth SMPCs structure. In work, we designed...