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1.
Hoyos-Montilla Ary A. Puertas F. Tobón Jorge I. 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2395-2410
Journal of Thermal Analysis and Calorimetry - The objective of this research is to know, through the flow of heat released, the effect of the addition of calcium hydroxide and the temperature on... 相似文献
2.
Tobón YA Nieto LI Romano RM Della Védova CO Downs AJ 《The journal of physical chemistry. A》2006,110(8):2674-2681
The photolytically induced reactions of a dihalogen XY (= Cl2, ICl, or IBr) with OCS isolated together in an Ar matrix at about 15 K lead to different photoproducts depending on the natures of X and Y. In addition to the known species ClCO*, OCCl2, syn-ClC(O)SCl, syn-ClC(O)SSCl, IC(O)Cl, IC(O)Br, and syn-BrC(O)SBr, syn-iodocarbonylsulfenyl bromide, syn-IC(O)SBr, has thus been identified for the first time as a photoproduct of the reactions involving IBr. The first product to be formed in the reactions with Cl2 or ICl is the ClCO* radical which reacts subsequently with halogen or sulfur atoms or other matrix guests to give the corresponding carbonyl dihalide (OCCl2 and IC(O)Cl), syn-ClC(O)SCl or syn-ClC(O)SSCl. The analogous reaction with IBr affords syn-BrC(O)SBr, IC(O)Br, and syn-IC(O)SBr. The changes have been followed, the products characterized experimentally by IR measurements, and the spectra analyzed in the light of the results of appropriate theoretical calculations. 相似文献
3.
Cabana J Ling CD Oró-Solé J Gautier D Tobías G Adams S Canadell E Palacín MR 《Inorganic chemistry》2004,43(22):7050-7060
Antifluorite-type lithium chromium oxide nitrides were prepared by solid-state reaction of Li(3)N, Li(2)O, and Cr(2)N. Depending on the reaction time and starting Li/Cr and O/Cr ratios, either an ordered or a disordered phase (or mixtures of both) is obtained. The formation of the former is favored by short reaction times and low Cr/O ratios whereas the formation of the latter is favored by higher Cr/O ratios and longer reaction times. The two phases were characterized, and the first one was confirmed to be the already reported Li(14)Cr(2)N(8)O phase, whereas the stoichiometry of the second is Li(10)CrN(4)O(2). Interestingly, even if both contain cationic vacancies in the structure, electrochemical lithium intercalation could only be achieved for Li(10)CrN(4)O(2). This phase exhibits a reversible capacity of 160 mAh/g very stable upon cycling. Bond valence and first-principles DFT calculations were carried out to understand the absence of lithium insertion in Li(14)Cr(2)N(8)O. Li-Li repulsion and destabilization of the tetrahedral CrN(4) units induced by occupation of the potential sites, as well as the absence of energetically favorable pathways for transport of the ions to these sites, are suggested to be the reasons. 相似文献
4.
Isolation of a dihalogen molecule XY (XY=Cl2, Br2, or BrCl) with CS2 in a solid Ar matrix at about 15 K leads, by broad-band UV-vis photolysis (200相似文献
5.
Yeny A. Tobón Rosana M. Romano Evamarie Hey‐Hawkins Roland Boese Carlos O. Della Védova 《Journal of Physical Organic Chemistry》2009,22(9):815-822
Potassium isopropyl xanthate, (CH3)2CHOC(S)SK, reacts with methyl chloroformiate ClC(O)OCH3 to yield (methoxycarbonyl) (2‐propoxythiocarbonyl) sulfide, (CH3)2CHOC(S)SC(O)OCH3. This novel xanthogen formate was characterized by 1H and 13C{1H} NMR spectroscopy, mass spectrometry and IR and Raman spectroscopy. The structure of a single crystal of (CH3)2CHOC(S)SC(O)OCH3 was determined by X‐ray diffraction analysis at 173 K. The conformational properties have been studied by liquid IR and Raman spectroscopy, matrix isolation spectroscopy together with photochemical studies and quantum chemical calculations (HF and B3LYP methods with the 6‐31+G* basis set). The analysis of the IR spectrum of liquid (CH3)2CHOC(S)SC(O)OCH3 suggests the presence of two conformers in equilibrium at room temperature. However, in the photochemical matrix study, an equilibrium of three conformers was detected. These forms were further characterized by theoretical calculations. Different photolysis products, such as CH3OC(O)SCH(CH3)2, OCS, CO, CO2 and CS2, were identified by matrix spectroscopy. The IR absorptions of CH3OC(O)SCH(CH3)2, for which literature data are scarce, were analysed in the light of the results of appropriate theoretical calculations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
6.
Dr. Neha P. Kamat Dr. Sylvia Tobé Ian T. Hill Prof. Jack W. Szostak 《Angewandte Chemie (International ed. in English)》2015,54(40):11735-11739
Cooperative interactions between RNA and vesicle membranes on the prebiotic earth may have led to the emergence of primitive cells. The membrane surface offers a potential platform for the catalysis of reactions involving RNA, but this scenario relies upon the existence of a simple mechanism by which RNA could become associated with protocell membranes. Here, we show that electrostatic interactions provided by short, basic, amphipathic peptides can be harnessed to drive RNA binding to both zwitterionic phospholipid and anionic fatty acid membranes. We show that the association of cationic molecules with phospholipid vesicles can enhance the local positive charge on a membrane and attract RNA polynucleotides. This phenomenon can be reproduced with amphipathic peptides as short as three amino acids. Finally, we show that peptides can cross bilayer membranes to localize encapsulated RNA. This mechanism of polynucleotide confinement could have been important for primitive cellular evolution. 相似文献
7.
J. I. Tobón J. Paya M. V. Borrachero L. Soriano O. J. Restrepo 《Journal of Thermal Analysis and Calorimetry》2012,107(1):233-239
In this article, the methodology to implementation of high resolution thermogravimetric analysis (HRTG) for construction materials
like Portland cement pastes is presented. The aim of this technique is to make easier the identification of the decomposition
reactions that frequently are overlapping on conventional thermogravimetric analysis (TG) like is the case of some mineral
phases in the cement pastes. The optimum parameters related to sample mass and purge flow gas were established. It is necessary
carried out the analysis with high quantity of sample (60 mg in this case) and without purge gas in order to get better results
and excellent reproducibility. The tests have average heating rate higher than 3 °C min−1 in the temperature range studied (35–300 °C), showing that the HRTG is not time-expensive technique. 相似文献
8.
Tobón YA Cozzarín MV Wang WG Ge MF Della Védova CO Romano RM 《The journal of physical chemistry. A》2011,115(36):10203-10210
ClC(O)SSCl was prepared by an improved method by the reaction of [(CH(3))(2)CHOC(S)](2)S with SO(2)Cl(2) in hexane. The photoelectron spectra in the gas phase present four distinct regions, corresponding to ionizations from electrons formally located at the S, O, and Cl atoms and at the C═O bond. The vibrational IR and Raman spectra of the liquid were interpreted in terms of the most stable syn-gauche conformer (the O═C double bond syn with respect to the S-S single bond and the C-S single bond gauche with respect to the S-Cl single bond) in equilibrium with the less stable anti-gauche form, both occurring in two enantiomeric forms. The randomization process between the conformers was induced by broad-band UV-visible irradiation in matrix conditions, and several photoproducts were identified by FTIR spectroscopy. The experimental results were complemented by theoretical calculations. 相似文献
9.
Thermal Behaviour of Pharmacologically Active Lithium Compounds 总被引:1,自引:0,他引:1
Tobón-Zapata G. E. Ferrer E. G. Etcheverry S. B. Baran E. J. 《Journal of Thermal Analysis and Calorimetry》2000,61(1):29-35
The thermal decompositions of a series of simple lithium compounds (carbonate, sulfate, acetate, citrates, aspartates and
glutamates) currently used in the treatment of manic-depressive psychosis and related disorders were investigated by means
of TG and DTA measurements in oxygen atmosphere. Pyrolysis residues were characterized by infrared spectroscopy. The stabilities
of the hydrates and intermediate phases generated during the degradation processes are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Ponou S Fässler TF Tobías G Canadell E Cho A Sevov SC 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(15):3615-3621
The new ternary phase Ba(5)In(4)Bi(5) was synthesized by direct reaction of the corresponding elements at high temperature. It crystallizes in a noncentrosymmetric space group and represents a new structure type (tetragonal, P4nc with a=10.620(2) and c=9.009(2) A, Z=2). The structure is built of interconnected heteroatomic clusters of In(4)Bi(5), square pyramids with In(4)-bases and four exo-bonded bismuth atoms (bond to the In atoms). According to Wade's rule the compound is electron-deficient with one electron per cluster, that is, [In(4)Bi(5)](10-) instead of the expected [In(4)Bi(5)](11-) for a closed-shell species. The clusters are discussed also in light of the known heteroatomic deltahedral clusters with the same composition but different charge, [In(4)Bi(5)](3-). Band structure calculations on the new compound suggest substantial participation of barium in the overall bonding of the structure that "accounts" for the electron shortage 相似文献