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21.
P. Ortiz M. A. Vázquez R. Ortiz J. M. Martin T. Ctvrtnickova M. P. Mateo G. Nicolas 《Applied Physics A: Materials Science & Processing》2010,100(3):965-973
The aim of the study was to characterize specimens submitted to the effects of weathering in an urban atmosphere. Samples
investigated were stones covered by crusts and deposits of thickness ranging from micrometers to millimetres due to traffic
pollutants and mineral dust. The pieces were collected in the Church of Santa Maria La Blanca in Seville (South Spain). In
the Historical Centre of this city, the traffic is the main source of sulphur oxides. 相似文献
22.
23.
Sucrose laurate is a detergent that is useful for various biochemical applications because it is a green compound and is easily degradable after hydrolysis with a lipase or esterase. One problem observed in the process of sucrose laurate degradation is that most commercial detergent preparations are impure, necessitating the hydrolysis of all of the sucrose esters present in the preparation, all of them with detergent properties. In this article, a highly active catalyst, which is able to perform the hydrolysis of commercial sucrose laurate, is presented. The use of glyoxyl agarose preparations of a previously aminated Thermomyces lanuginosa lipase (TLL) enabled complete hydrolysis, in less than 30 min, of all of the compounds that comprise the mixture. In addition, this derivative is stable in the presence of 20% ethanol, which is necessary to prevent microbial contamination. 相似文献
24.
We present a systematic study on the excited electron-bubble states in superfluid (4)He using a time-dependent density functional approach. For the evolution of the 1P bubble state, two different functionals accompanied with two different time-development schemes are used, namely an accurate finite-range functional for helium with an adiabatic approximation for electron versus an efficient zero-range functional for helium with a real-time evolution for electron. We make a detailed comparison between the quantitative results obtained from the two methods, which allow us to employ with confidence the optimal method for suitable problems. Based on this knowledge, we use the finite-range functional to calculate the time-resolved absorption spectrum of the 1P bubble, which in principle can be experimentally determined, and we use the zero-range functional to real-time evolve the 2P bubble for several hundreds of picoseconds, which is theoretically interesting due to the break down of adiabaticity for this state. Our results discard the physical realization of relaxed, metastable configurations above the 1P state. 相似文献
25.
Alajarin M Bonillo B Ortin MM Orenes RA Vidal A 《Organic & biomolecular chemistry》2011,9(19):6741-6749
N-(2-azidomethyl)phenyl ketenimines and N-(2-azidomethyl)phenyl-N'-alkyl(aryl) carbodiimides undergo, under mild thermal conditions, intramolecular [3 + 2] cycloaddition reactions between the azido group and either the C=C or the distal C=N double bonds of the ketenimine and carbodiimide functions respectively. The reaction products are indolo[1,2-a]quinazolines and/or indolo[2,1-b]quinazolines in the case of azido-ketenimines, and tetrazolo[5,1-b]quinazolines in the case of azido-carbodiimides. The formation of the two classes of indoloquinazolines implies the ulterior dinitrogen extrusion from the non-isolated, putative [3 + 2] cycloadducts between the azide and ketenimine functions, whereas in the case of azido-carbodiimides the initial cycloadducts, tetrazoloquinazolines, were cleanly isolated and further converted into 2-aminoquinazolines by thermally induced dinitrogen extrusion. 相似文献
26.
Sensilla comprising the sensory equipment of the antennal flagellum of eight species of Damalinia were studied using light and scanning electron microscopy. The sensillar complex consists of three pore organs and two sensilla coeloconica in both males and females. No relationship between their relative position in different genera and species has been found. The ‘pit organs' of the sensilla coeloconica have different shapes according to species. In the apex of the male flagellum, teeth are present in the species studied but the number and shapes are different. Adjacent to the teeth is a cluster of sensilla basiconica. At high magnification, no pores were found in the sensilla walls but their more or less blunt tips have small pores. The inner face of the male flagellum can be serrated or non-serrated. 相似文献
27.
Z Pawlicová J R Albert-García I Sahuquillo Mateo J V García M Catalá Icardo J Martínez Calatayud 《Analytical sciences》2006,22(1):29-34
A new, robust and simple method is proposed for the chemiluminescent determination of the pesticide Bromoxynil. The empirical procedure is performed with the aid of a flow-injection manifold provided with an on-line photo-reactor to obtain chemiluminescent photofragments. After a period of 12 s of irradiation with an 8 W low-pressure mercury lamp, a chemiluminescent oxidation was performed with the system potassium permanganate in a polyphosphoric acid medium. The photolysis required a basic medium (KOH 0.014 mol l(-1)) with ethanol (1%) as a sensitizer. The method allowed the determination of 134 samples (h-1) of Bromoxynil in a wide interval of concentrations, over the range 5 x 10(-3) - 1 mg l(-1); the detection limit was 5 x 10(-3) mg l(-1). The RSD (n=24) at 0.25 mg l(-1) of the pesticide level was 2.3%. The method was applied to a water sample and to a formulation. 相似文献
28.
Alajarín M Sánchez-Andrada P López-Leonardo C Alvarez A 《The Journal of organic chemistry》2005,70(19):7617-7623
[reactions: see text] Condensation reaction of o-phthalaldehyde with primary amines is a classical method for the synthesis of phthalimidines. Although the intermediacy of the corresponding monoimines has been occasionally proposed, the mechanism of their transformation into phthalimidines remains to be elucidated. We present here theoretical evidence supporting a three-step mechanistic pathway for that transformation involving the [1,5]-H sigmatropic rearrangement of the aldehydic proton leading to an intermediate (aminovinyl)ketene as the key step. Other alternative routes have been calculated to be energetically less favorable. Similar transformations of related imino aldehydes enclosing a 5-aza-2,4-pentadienal skeleton via [1,5]-H shifts are also studied. 相似文献
29.
Antonio?de?la?Hoz Ana?Sánchez-Migallón María?del?Carmen?Mateo Pilar?Prieto Lourdes?Infantes José?ElgueroEmail author 《Structural chemistry》2005,16(5):485-490
2H-Imidazole derivative 5 has been synthesized and characterized by the X-ray diffraction (XRD) method. The compound crystallizes in the monoclinic space group Cc with cell parameters a = 19.398(1), b = 8.890(1), c = 10.247(1), β = 110.76(1), Z = 4. The molecules are inter-linked through C–H⋅sO and C–H⋅sπ interactions forming infinite chains. 相似文献
30.
Marco Carini Mauro Marongiu Karol Strutyski Akinori Saeki Manuel Melle‐Franco Aurelio Mateo‐Alonso 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15935-15939
Supramolecular polymers show great potential in the development of new materials because of their inherent recyclability and their self‐healing and stimuli‐responsive properties. Supramolecular conductive polymers are generally obtained by the assembly of individual aromatic molecules into columnar arrays that provide an optimal channel for electronic transport. A new approach is reported to prepare supramolecular polymers by hooking together sigmoidal monomers into 1D arrays of π‐stacked anthracene and acridine units, which gives rise to micrometer‐sized fibrils that show pseudoconductivities in line with other conducting materials. This approach paves the way for the design of new supramolecular polymers constituted by acene derivatives with enhanced excitonic and electronic transporting properties. 相似文献