Synthesis and characterization of rhenium (vii) and rhuthenium (ii) dendritic catalysts: oxidative cleavage and epoxidation of alkenes

>Magister Scientiae - MScHerein we report the successful synthesis of a class of stable and flexible Schiff-base chelators capable of coordinating both ruthenium (II) and rhenium (VII) and which would be catalytically active for oxo-transfer reactions. The synthesis of bidentate (L1), tetradentate (L2-L3), and multidendate ligands (DL1-DL4) of nitrogen was a result of a reaction of primary amine with 2-pyridinecarboxaldehyde. Ligand (L3) is reported herein for the first time. The amines (n-propylamine, ethylenediamine, butanediamine, diaminobutane, propylene iminopyridyl (DAB-PPI) dendrimer) were varied as to afford metal complexes that exhibit different physical and chemical properties. The ligands were isolated and fully characterized by IR, NMR spectroscopy and elemental (H, C, N) analysis.The Schiff-base complexes of methyltrioxorhenium (MTO): Methyl(n-pyridin-2-yl)methylene)propan-1-amine)trioxorhenium (C1), Methyl([bis(pyridin-2- yl)formylidene]butane-1,4-diamine)trioxorhenium (C2), Methyl(diaminobutane propylene imonopyridyl)trioxorhenium G1(DC1) and G2(DC2) have exhibited sensitivity to water than MTO itself. Rapid ligand-exchange reactions in solution are observed at elevated temperatures. The MTO Schiff-base complexes are also slightly sensitive to light and slowly decompose as they are exposes to air. These complexes were isolated and fully characterized by IR, NMR, UV-Vis, EA and MS. In the ESI mass spectra of compound C1-C2 and DC1-DC2 show the peaks of the Schiff-base ligand and the MTO moiety separately, without a traceable fragmentation pattern. The isotopic cluster and the molecular ion peak were observed.The mononuclear ruthenium compounds (B1 and B3) were prepared from dichlorotetrakis(dimethyl sulfoxide)ruthenium (II) metal precursor by reacting the synthesized ligands (L2 and L3) with the metal precursor. Compounds (B2 and B4) were obtained by subsequently stabilizing the neutral compounds (B1 and B2) as hexaflourophosphate salts via metathesis employing thallium (I) hexafluorophosphate (V).The homobimetallic cationic compound (B5) was synthesized by reacting the dinuclear complex [(p-cymene)2RuCl2]2 with ligand (L4).The neutral tetranuclear (V1 and V3) and octanuclear (V2 and V4) (N,N) ruthenium(II) metallodendrimers were synthesized mimicking the same route as for the neutral mononuclear compounds (B1 and B3). The compounds (V1-V4) were prepared from the dichlotetrakis(dimethyl sulfoxide)ruthenium(II) based on the synthesized dendritic scaffolds (DL1-DL4). Compounds (V5 and V6) were fashioned in a similar manner to compound (B5),by reacting the iminopyridyl dendritic scaffolds (DL1 and DL3) with the dinuclear precursor[(p-cymene)2RuCl2]2 to afford two complexes of the type [{(p-cymene)RuCl2}4G1, V5] and [{p-cymene)RuCl2}8G2, V6]. Electronic spectra of the prepared complexes were obtained (in a Sharpless Biphasic solvent system: CCl4:MeCN:H2O) in order to understand the nature of the active species in the catalytic cycle and to propose a mechanism for the catalytic cycle .Confirmation of the prepared complexes (B1-V6) was done using several spectroscopic techniques (IR, NMR, UV-Vis, ESI-MS) in conjuction with elemental analysis.The compounds C1-DC2 were then tested towards the epoxidation of selected cyclic alkenesi.e cyclohexene and cis-cyclooctene, respectively and straight chain alkenes. The catalyzed epoxidation reactions were carried out at room temperature employing using Urea hydrogen peroxide adduct (UHP) as the oxidant and dichlomethane (DCM) as the solvent. The complexes displayed high catalytic activity and selectivity when applied to the epoxidation of cyclohexene and cis-cyclooctene with urea hydrogen peroxide adduct (UHP) as oxidant in dicholoromethane. The epoxidation reaction was quantified using gas chromatography.Conversions reached 100% for all the complexes within 6 hours. The catalytic activity of complex C1 and C2 was relatively low compared to the catalytic activity of complex DC1 and DC2

Synthesis, characterization, and molecular docking of novel 4-Aminoquinolines and Salicylaldimine complexes: evaluation as antimalarial and antitumor agents

Philosophiae Doctor - PhD (Chemistry)Malaria remains a major global health problem and to date, hundreds of thousands of people die as a result of this disease every year. Malaria has been able to adapt and rebound despite various efforts made to combat the disease. The decrease in efficacy of many front-line drugs against malaria, due to increased resistance, prompts investigation into obtaining effective compounds that are able to overcome this resistance. This study investigated the synthesis, characterisation and biological evaluation of new quinoline (as antimalarial agents) as well as non-quinoline (as antitumor agents) based compounds

CAOS spectroscopy of Am stars Kepler targets

The {\it Kepler} space mission and its {\it K2} extension provide photometric time series data with unprecedented accuracy. These data challenge our current understanding of the metallic-lined A stars (Am stars) for what concerns the onset of pulsations in their atmospheres. It turns out that the predictions of current diffusion models do not agree with observations. To understand this discrepancy, it is of crucial importance to obtain ground-based spectroscopic observations of Am stars in the {\it Kepler} and {\it K2} fields in order to determine the best estimates of the stellar parameters. In this paper, we present a detailed analysis of high-resolution spectroscopic data for seven stars previously classified as Am stars. We determine the effective temperatures, surface gravities, projected rotational velocities, microturbulent velocities and chemical abundances of these stars using spectral synthesis. These spectra were obtained with {\it CAOS}, a new instrument recently installed at the observing station of the Catania Astrophysical Observatory on Mt. Etna. Three stars have already been observed during quarters Q0-Q17, namely: HD\,180347, HD\,181206, and HD\,185658, while HD\,43509 was already observed during {\it K2} C0 campaign. We confirm that HD\,43509 and HD\,180347 are Am stars, while HD 52403, HD\,50766, HD\,58246, HD\,181206 and HD\,185658 are marginal Am stars. By means of non-LTE analysis, we derived oxygen abundances from O{\sc I}$\lambda$7771--5{\AA} triplet and we also discussed the results obtained with both non-LTE and LTE approaches.Comment: accepted in MNRAS main journal 13 pages, 11 figures, 3 tables. arXiv admin note: text overlap with arXiv:1404.095

A CNN and LSTM-based Model for Creating Captions for Photos

Can a machine interpret an image's meaning with the same speed as the human brain when it is seen? This problem was heavily researched by computer vision specialists, who believed it to be unsolvable until recently. It is now possible to develop models that can generate captions for pictures because of advancements in deep learning techniques, accessibility to large datasets, and processing power. This will be accomplished by the Python-based implementation of the article's deep learning convolutional neural network technique and a particular kind of recurrent neural network. Here the proposed model uses CNN and LSTM methods to achieve desired tas

Anomalous scaling of passively advected magnetic field in the presence of strong anisotropy

Inertial-range scaling behavior of high-order (up to order N=51) structure functions of a passively advected vector field has been analyzed in the framework of the rapid-change model with strong small-scale anisotropy with the aid of the renormalization group and the operator-product expansion. It has been shown that in inertial range the leading terms of the structure functions are coordinate independent, but powerlike corrections appear with the same anomalous scaling exponents as for the passively advected scalar field. These exponents depend on anisotropy parameters in such a way that a specific hierarchy related to the degree of anisotropy is observed. Deviations from power-law behavior like oscillations or logarithmic behavior in the corrections to structure functions have not been found.Comment: 15 pages, 18 figure

A network-based target overlap score for characterizing drug combinations: High correlation with cancer clinical trial results

Drug combinations are highly efficient in systemic treatment of complex multigene diseases such as cancer, diabetes, arthritis and hypertension. Most currently used combinations were found in empirical ways, which limits the speed of discovery for new and more effective combinations. Therefore, there is a substantial need for efficient and fast computational methods. Here, we present a principle that is based on the assumption that perturbations generated by multiple pharmaceutical agents propagate through an interaction network and can cause unexpected amplification at targets not immediately affected by the original drugs. In order to capture this phenomenon, we introduce a novel Target Overlap Score (TOS) that is defined for two pharmaceutical agents as the number of jointly perturbed targets divided by the number of all targets potentially affected by the two agents. We show that this measure is correlated with the known effects of beneficial and deleterious drug combinations taken from the DCDB, TTD and Drugs.com databases. We demonstrate the utility of TOS by correlating the score to the outcome of recent clinical trials evaluating trastuzumab, an effective anticancer agent utilized in combination with anthracycline- and taxane-based systemic chemotherapy in HER2-receptor (erb-b2 receptor tyrosine kinase 2) positive breast cancer. © 2015 Ligeti et al

A Multi-Wavelength Perspective of Flares on HR 1099: Four Years of Coordinated Campaigns

We report on four years of multiple wavelength observations of the RS CVn system V711 Tau (HR 1099) from 1993, 1994, 1996, and 1998. This combination of radio, ultraviolet, extreme ultraviolet, and X-ray observations allows us to view, in the most comprehensive manner currently possible, the coronal and upper atmospheric variability of this active binary system. We report on the changing activity state of the system as recorded in the EUV and radio across the four years of the observations, and study the high energy variability using an assemblage of X-ray telescopes. (Longer abstract in paper).Comment: manuscript is 110 pages in length; 36 figures tota

Delineating the GRIN1 phenotypic spectrum: a distinct genetic NMDA receptor encephalopathy

Objective:To determine the phenotypic spectrum caused by mutations in GRIN1 encoding the NMDA receptor subunit GluN1 and to investigate their underlying functional pathophysiology.Methods:We collected molecular and clinical data from several diagnostic and research cohorts. Functional consequences of GRIN1 mutations were investigated in Xenopus laevis oocytes.Results:We identified heterozygous de novo GRIN1 mutations in 14 individuals and reviewed the phenotypes of all 9 previously reported patients. These 23 individuals presented with a distinct phenotype of profound developmental delay, severe intellectual disability with absent speech, muscular hypotonia, hyperkinetic movement disorder, oculogyric crises, cortical blindness, generalized cerebral atrophy, and epilepsy. Mutations cluster within transmembrane segments and result in loss of channel function of varying severity with a dominant-negative effect. In addition, we describe 2 homozygous GRIN1 mutations (1 missense, 1 truncation), each segregating with severe neurodevelopmental phenotypes in consanguineous families.Conclusions:De novo GRIN1 mutations are associated with severe intellectual disability with cortical visual impairment as well as oculomotor and movement disorders being discriminating phenotypic features. Loss of NMDA receptor function appears to be the underlying disease mechanism. The identification of both heterozygous and homozygous mutations blurs the borders of dominant and recessive inheritance of GRIN1-associated disorders.Johannes R. Lemke (32EP30_136042/1) and Peter De Jonghe (G.A.136.11.N and FWO/ESF-ECRP) received financial support within the EuroEPINOMICS-RES network (www.euroepinomics.org) within the Eurocores framework of the European Science Foundation (ESF). Saskia Biskup and Henrike Heyne received financial support from the German Federal Ministry for Education and Research (BMBF IonNeurONet: 01 GM1105A and FKZ: 01EO1501). Katia Hardies is a PhD fellow of the Institute for Science and Technology (IWT) Flanders. Ingo Helbig was supported by intramural funds of the University of Kiel, by a grant from the German Research Foundation (HE5415/3-1) within the EuroEPINOMICS framework of the European Science Foundation, and additional grants of the German Research Foundation (DFG, HE5415/5-1, HE 5415/6-1), German Ministry for Education and Research (01DH12033, MAR 10/012), and grant by the German chapter of the International League against Epilepsy (DGfE). The project also received infrastructural support through the Institute of Clinical Molecular Biology in Kiel, supported in part by DFG Cluster of Excellence "Inflammation at Interfaces" and "Future Ocean." The project was also supported by the popgen 2.0 network (P2N) through a grant from the German Ministry for Education and Research (01EY1103) and by the International Coordination Action (ICA) grant G0E8614N. Christel Depienne, Caroline Nava, and Delphine Heron received financial support for exome analyses by the Centre National de Genotypage (CNG, Evry, France)