Search results for "Homogeneous"
showing 10 items of 718 documents
Highly Robust but Surface-Active : An N-Heterocyclic Carbene-Stabilized Au25 Nanocluster
2019
Surface organic ligands play a critical role in stabilizing atomically precise metal nanoclusters in solutions. However, it is still challenging to prepare highly robust ligated metal nanoclusters that are surface-active for liquid-phase catalysis without any pre-treatment. Now, an N-heterocyclic carbene-stabilized Au25 nanocluster with high thermal and air stabilities is presented as a homogenous catalyst for cycloisomerization of alkynyl amines to indoles. The nanocluster, characterized as [Au25(iPr2-bimy)10Br7]2+ (iPr2-bimy=1,3-diisopropylbenzimidazolin-2-ylidene) (1), was synthesized by direct reduction of AuSMe2Cl and iPr2-bimyAuBr with NaBH4 in one pot. X-ray crystallization analysis …
Influence of regionality and maturation time on the chemical fingerprint of whisky.
2020
International audience; Understanding the chemical composition of whisky and the impact of each step in the manufacturing process provides a basis for responding to the challenges of producing high quality spirits. In this study, the objective was to discriminate whiskies according to their geographical origin and authenticate the maturation time in cask based on the non-volatile profiles. The combination of FT-ICR-MS and chemometrics allowed the distinction of whiskies from four geographical origins in Scotland (Highlands, Lowlands, Speyside and Islay). Statistical modeling was also used to discriminate whiskies according to the maturation time in cask and reveal chemical markers associate…
¿Solamente platos? Cerámicas de barniz rojo en el depósito ibérico del Zacatín (Granada)
2015
We have taken, as a subject of our study, a homogeneous set of red indigenous glazed plates with a very particular profile and without a parallel known for the present time. The above mentioned set was part of the ritual deposit found in Zacatin, a very typical street from Granada. This deposit is a pit close to the River Darro which was filled with the waste of a sacred banquet, possibly related to this same river. In this work we consider the fact that these plates were made ex profeso for the ritual that took place out of Iliberri 's walls, around 370 B.C.
Sources, degassing, and contamination of CO2, H2O, He, Ne, and Ar in basaltic glasses from Kolbeinsey Ridge, North Atlantic
2005
Abstract New volatile data (CO2, H2O, He, Ne, and Ar) are presented for 24 submarine basaltic glasses from the Kolbeinsey Ridge, Tjornes Fracture Zone and Mohns Ridge, North Atlantic. Low CO2 and He contents indicate that magmas were strongly outgassed with the extent of degassing increasing toward the south, as expected from shallower ridge depths. Ne and Ar are significantly more abundant in the southernmost glasses than predicted for degassed melt. The strong atmospheric isotopic signal associated with this excess Ne and Ar suggests syn- or posteruptive contamination by air. Degassing, by itself, cannot generate the large variations in δ13C values of dissolved CO2 or coupled CO2-Ar varia…
A convenient route for the preparation of the monohydride catalyst trans-[RuCl(H)(dppe)2] (dppe=Ph2PCH2CH2PPh2): improved synthesis and crystal struc…
2013
Abstract A novel and improved room temperature synthesis of the monohydride catalyst trans-[RuCl(H)(dppe)2] complex (1, dppe (1,2-bis(diphenylphosphino)ethane) = Ph2PCH2CH2PPh2) proceeds through oxidation of methanol (the solvent) by the pentacoordinated cis-[RuCl(dppe)2][PF6] complex and t-BuOK as the base is described. Compound 1 was fully characterized by NMR (1H, 13C, 31P), ESI-MS(TOF +), FTIR and elemental analysis. The X-ray structure of 1 was reported for the first time and unambiguously confirms the trans-configuration of the complex.
New upper bounds for some instances from benchmark for vector packing problem
2021
This dataset is a result of the research: Đorđe Stakić, Miodrag Živković, Ana Anokić, "A Reduced Variable Neighborhood Search Approach to the Heterogeneous Vector Bin Packing Problem", Information Technology and Control, 2021, 50(4), 808-826, https://doi.org/10.5755/j01.itc.50.4.29009 Files are given by algorithm described in it. This dataset consists of 14 solutions with better bounds for instances described in paper: Heßler, K., Gschwind, T., Irnich, S. Stabilized branch-and-price algorithms for vector packing problems. European Journal of Operational Research, 2018, 271(2), 401-419. https://doi.org/10.1016/j.ejor.2018.04.047 File structure: Instance name: UB: solut…
Binge Drinking: The Top 100 Cited Papers
2021
We conducted a review to analyze the 100 most-cited studies on binge drinking (BD) in the Web of Science (WoS) database to determine their current status and the aspects that require further attention. We carried out a retrospective bibliometric analysis in January 2021. The year of publication, authors, design, subject, journal, institution and lead author’s country, as well as the definition of BD, were extracted from the articles. The data on the country, year, thematic category of the journals and their rank were obtained from the Institute for Scientific Information (ISI) Journal Citation Reports 2020. The number of citations was collected from the WoS, and the h index was collected fr…
Low temperature optical spectroscopy of low-spin ferric hemeproteins
1996
We report the Soret absorption spectra (500-350 nm) of the cyanomet derivatives of human hemoglobin and horse myoglobin, in the temperature range 300-20 K and in two different solvents (65% v/v glycerol-water or 65% v/v ethylene glycol-water). In order to obtain information on stereodynamic properties of active site of the two hemeproteins, we perform an analysis of the band profiles within the framework of electron-vibrations coupling. This approach enables us to single out the various contributions to the spectral bandwidth, such as those arising from non-radiative decay of the excited electronic state (homogeneous broadening) and from the coupling of the electronic transition i) with hig…
Interesterification of rapeseed oil catalyzed by tin octoate
2014
The interesterification of rapeseed oil was performed for the first time by using tin octoate as Lewis acid homogeneous catalysts and methyl or ethyl acetate as acyl acceptors in a batch reactor, within the temperature range 393e483 K. The yields in fatty acid ethyl esters (FAEE) and triacetin (TA) after 20 h of reaction time increased from 8% and 2%eto 61% and 22%, respectively, when the reaction temperature increased from423 to 483 K. An optimum value of 40 for the acyl acceptor to oil molar ratio was found to be necessary to match good fatty acid alkyl ester yields with high enough reaction rate. The rate of generation of esters was significantly higher when methyl acetate was used as acyl …
Palladium-Catalyzed Arylation of Linear and Cyclic Polyamines.
2005
Synthetic protocols for the palladium-catalyzed arylation of various linear and cyclic polyamines and polyoxapolyamines has been worked out. Pd(0) and Pd(II) complexes with such phosphine ligands as dppf, BINAP, PPF-OMe, P(tBu) 3 , 2-ditert-butylphosphino- 1,1'-biphenyl have been explored in the catalytic amination reactions. Monoamination of chloro-, bromo-, and iodoarenes with di-, tri-, and tetraamines have been carried out, condi- tions for di- and polyarylation of linear polyamines have been elaborated. Successful aryla- tion of 1,4,7,10-tetraazacyclododecane (cyclene) and 1,4,8,11-tetraazacyclotetradecane (cy- clam) have been conducted. Intramolecular diamination of dihaloarenes such …