Emergent universe from scale invariant two measures theory

The dilaton-gravity sector of a linear in the scalar curvature, scale invariant Two Measures Field Theory (TMT), is explored in detail in the context of closed FRW cosmology and shown to allow stable emerging universe solutions. The model possesses scale invariance which is spontaneously broken due to the intrinsic features of the TMT dynamics. We study the transition from the emerging phase to inflation, and then to a zero cosmological constant phase. We also study the spectrum of density perturbations and the constraints that impose on the parameters of the theory.     

Thiourea catalyzed organocatalytic enantioselective Michael addition of diphenyl phosphite to nitroalkenes

Bifunctional thiourea catalyzes the enantioselective Michael addition reaction of diphenyl phosphite to nitroalkenes. This methodology provides a facile access to enantiomerically enriched β-nitrophosphonates, precursors for the preparation of synthetically and biologically useful β-aminophosphonic acids. DFT level of computational calculations invoke the attack of the diphenyl phosphite to the nitroolefin by the Re face, this give light to this scarcely explored process update in the literature. The computational calculations support the absolute configuration obtained in the final adducts.     

Enantioselective α- and γ-alkylation of α,β-unsaturated aldehydes using dienamine activation

The enantioselective alkylation of α,β-unsaturated aldehydes with stabilized carbocations as electrophiles via the activation as dienamine intermediates is described. This unique application of dienamine catalysis allows for the first enantioselective γ-alkylation of linear α,β-unsubstituted enals.     

Intramolecular Michael reaction of tert-butylsulfinyl ketimines: asymmetric synthesis of 3-substituted indanones

Aromatic tert-butylsulfinyl ketimines bearing a suitable Michael acceptor at the ortho position readily undergo an intramolecular conjugate addition achieving indanone derivatives in good yields and complete diastereoselectivity.     

Molecular and Electronic‐Structure Basis of the Ambipolar Behavior of Naphthalimide–Terthiophene Derivatives: Implementation in Organic Field‐Effect Transistors

A new family of naphthalimide‐fused thienopyrazine derivatives for ambipolar charge transport in organic field‐effect transistors is presented. Their electronic and molecular structures were elucidated through optical and vibrational spectroscopy aided by DFT calculations. The results indicate that these compounds have completely planar molecular skeletons which promote good film crystallinity and low reorganization energies for both electron and hole transport. Their performance in organic field‐effect transistors is compared with twisted and planar naphthaleneamidine monoimide‐fused terthiophenes in order to understand the origin of ambipolarity in this new series of molecular semiconductors.     

Base‐Dependent Stereodivergent Intramolecular Aza‐Michael Reaction: Asymmetric Synthesis of 1,3‐Disubstituted Isoindolines

The nucleophilic addition (A_N) / intramolecular aza‐Michael reaction (IMAMR) process on Ellman’s tert‐butylsulfinyl imines, bearing a Michael acceptor in the ortho position, is studied. This reaction affords 1,3‐disubstituted isoindolines with a wide range of substituents in good yields and diastereoselectivities. Interestingly, careful choice of the base for the aza‐Michael step allows either the cis or the trans diastereoisomers to be exclusively obtained. This stereodivergent cyclization has enabled the synthesis of C₂‐symmetric bisacetate‐substituted isoindolines. In addition, bisacetate isoindolines bearing two well‐differentiated ester moieties are also noteworthy because they may allow for the orthogonal synthesis of β,β′‐dipeptides using a single nitrogen atom as a linchpin.     

Synthesis and Diels-Alder cycloadditions of exo-imidazolidin-2-one dienes

An efficient and versatile synthesis of novel exo-imidazolidin-2-one dienes is described. This involves the base-assisted condensation/cyclization cascade reaction of the monoimino derivatives of diacetyl with a series of isocyanates. This methodology enables preparation of symmetrical dienes, as long as the substrates have the same N substituent. Moreover, use of different N-substituted starting materials leads to formation of nonsymmetrical dienes. The reactivity of these dienes was evaluated in Diels-Alder reactions, showing a high reactivity.     

Tachyon-Chaplygin inflationary universe model

Tachyonic inflationary universe model in the context of a Chaplygin gas equation of state is studied. General conditions for this model to be realizable are discussed. By using an effective exponential potential we describe in great details the characteristic of the inflationary universe model. The parameters of the model are restricted by using recent astronomical observations.     

Preparation of epidermal growth factor (EGF) conjugated iron oxide nanoparticles and their internalization into colon cancer cells

Epidermal growth factor (EGF) was conjugated with carboxymethyldextran (CMDx) coated iron oxide magnetic nanoparticles using carbodiimide chemistry to obtain magnetic nanoparticles that target the epidermal growth factor receptor (EGFR). Epidermal growth factor modified magnetic nanoparticles were colloidally stable when suspended in biological buffers such as PBS and cell culture media. Both targeted and non-targeted nanoparticles were incubated with CaCo-2 cancer cells, known to overexpress EGFR. Nanoparticle localization within the cell was visualized by confocal laser scanning microscopy and light microscopy using Prussian blue stain. Results showed that targeted magnetic nanoparticles were rapidly accumulated in both flask-shaped small vesicles and large circular endocytic structures. Internalization patterns suggest that both clathrin-dependent and clathrin-independent receptors mediated endocytosis mechanisms are responsible for nanoparticle internalization.     

The slowing-down thickness dependency of some neutron flux parameters fork 0-standardization

The experimental dependence of the α,f andT _n parameters, in function of the water thickness, for different irradiation channels of Triga Mark III reactor, were analyzed. An exponential law for the α(r) dependence was obtained in the neighborhood of the active zone of the reactor numerically modelated using theS _n method for 69 neutrons groups, and this dependence is slower in light water reactors than in graphite reactors.