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101.
Alain Tundidor-Camba Nélida Araya Carmen M. González-Henríquez Luis H. Tagle René A. Hauyon Patricio A. Sobarzo Fidel E. Rodríguez-González Ignacio A. Jessop Gonzalo Recabarren-Gajardo Claudio A. Terraza 《应用聚合物科学杂志》2019,136(42):48055
Three new diamines derived from epoxide compounds were synthesized. The preparation of diamine monomers implied the reaction between a phenoxyalkyloxirane (alkyl: H, methyl, isopropyl) and bisphenol A, obtaining the respective aliphatic diols, which produced the corresponding dinitro derivatives. Finally, these derivatives were reduced by using palladium/carbon activated as catalyst and hydrazine as a hydrogen source. Then, six oligomeric poly(ether-azomethine)s (PEAzMs) were obtained from a polycondensation reaction between the new diamines and bis(4-formylbiphenyl-4-yl)dialkylsilane (alkyl: methyl, phenyl) with 84–93% yields. The structural characterization of the diamines and PEAzMs was performed by elemental analysis, infrared spectroscopy, and nuclear magnetic resonance spectroscopy (1H, 13C, and 29Si). Furthermore, polymers were analyzed by solubility tests, gel permeation chromatography, ultraviolet–visible (UV–vis) spectroscopy, thermogravimetry, and differential scanning calorimetry analysis. The results showed PEAzMs with 2–11 repetitive units, where the design of the monomers allowed to obtain improved solution processability in comparison with previously reported silylated poly(azomethine)s and good thermal stability. Additionally, all samples showed high transparency in the UV–vis region. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48055. 相似文献
102.
Healthy hair and skin is highly desired. Characterization of their morphological, frictional, and adhesive properties (tribological properties) is essential to enhance understanding of hair and skin and to advance the science. Literature on the tribological characterization of hair and skin is scarce to date. The paper presents nanotribological data and analysis on hair (Caucasian, Asian, and African hair at virgin, chemo-mechanically damaged, and treated conditions) and synthetic hair and skin, as well as roughness data of human skin replica. Roughness statistics are presented to characterize the vertical and spatial surface parameters. Average coefficient of friction values were determined for each ethnicity and hair type, and are discussed. The directionality dependence of friction is also discussed. Magnitude and spatial distribution of adhesive force are used to estimate thickness and distribution of the conditioner film. 相似文献
103.
Pedro J. Sánchez-Soto María del Carmen Jiménez de Haro Luis A. Pérez-Maqueda Ignacio Varona José L. Pérez-Rodríguez 《Journal of the American Ceramic Society》2000,83(7):1649-1657
The present study examined the effects of dry grinding, using ball-milling, on the structure of reference well-crystallized (KGa-1) and poorly crystallized (KGa-2) kaolinite powders from Georgia. Grinding produced a strong structural alteration, mainly along the c axis, resulting in disorder and total degradation of the crystal structure of the kaolinite and the formation of an amorphous product. The surface area increased with grinding time, mainly in KGa-2 (maximum value 50.27 m2 /g), a result associated with particle-size reduction. These particles became more agglomerated with grinding, and the surface area decreased after 30 min, as confirmed by scanning electron microscopy and particle-size-distribution analysis. There was a limit to particle-size reduction with grinding time. When grinding time was increased, the original endothermic differential thermal analysis (DTA) effects of dehydroxylation in both samples shifted to lower temperatures, decreased in intensity, then disappeared completely after 120 min of grinding. The temperature of the characteristic first exothermic effect shifted slightly to lower temperatures with grinding, although the DTA effects did not increase with grinding time in either kaolinite sample, at least up to 325 min. The amorphous, mechanically activated kaolinite converted into low-crystalline mullite nuclei at a lower temperature than did the unground samples, as deduced by thermal and X-ray observations. This effect was especially important for the KGa-2 sample. Grinding did not seem to influence the formation of silicon-aluminum spinel from kaolinite. The present results may explain why ground kaolinite samples prepared via different routes—e.g., with differences in grinding—behave differently during high-temperature transformations, as reported in the related literature. 相似文献
104.
Fitó M Covas MI Lamuela-Raventós RM Vila J Torrents L de la Torre C Marrugat J 《Lipids》2000,35(6):633-638
The protective effect of phenolic compounds from an olive oil extract, and of olive oils with (extra-virgin) and without (refined)
phenolic components, on low density lipoprotein (LDL) oxidation was investigated. When added to isolated LDL, phenolics [0.025–0.3
mg/L caffeic acid equivalents (CAE)] increased the lag time of conjugated diene formation after copper-mediated LDL oxidation
in a concentration-dependent manner. Concentrations of phenolics greater than 20 mg/L inhibited formation of thiobarbituric-acid
reactive substances after AAPH-initiated LDL oxidation. LDL isolated from plasma after preincubation with phenolics (25–160
mg/L CAE) showed a concentration-dependent increase in the lag time of conjugated diene formation after copper-mediated LDL
oxidation. Refined olive oil (0 mg/L CAE) and extra-virgin olive oil (0.1 and 0.3 mg/L CAE) added to isolated LDL caused an
increase in the lag time of conjugated diene formation after copper-mediated LDL oxidation that was related to olive oil phenolic
content. Multiple regression analysis showed that phenolics were significantly associated with the increase in lag time after
adjustment for effects of other antioxidants; α-tocopherol also achieved a statistically significant effect. These results
indicate that olive oil phenolic compounds protect LDL against peroxyl radical-dependent and metal-induced oxidation in vitro and could associate with LDL after their incubation with plasma. Both types of olive oil protect LDL from oxidation. Olive
oil containing phenolics, however, shows more antioxidant effect on LDL oxidation than refined olive oil. 相似文献
105.
Carmen Baudín Jonas Gurauskis Antonio Javier Sánchez-Herencia Victor M. Orera 《Journal of the American Ceramic Society》2009,92(1):152-160
Fracture features, residual stresses, and zirconia transformation are studied in indentation strength specimens of alumina-Y2 O3 -stabilized zirconia (3% mol of Y2 O3 , 3YTZP) ceramics in order to analyze the extension of the indentation damage in the bulk of the specimens. Two compositions, 5 vol% 3YTZP (A5) and 40 vol% 3YTZP (A40), have been prepared by stacking tape-casted tapes and sintering. After indentation with loads ranging from 50 to 300 N, samples were fractured in four-point bending and the fracture surfaces were characterized by scanning electron microscopy. Raman and piezospectroscopic techniques were used to determine the monoclinic zirconia fraction and the residual stresses through the fracture surfaces. In the A5 composition, the indentation damage morphology was clearly half-penny, whereas the A40 composition presented Palmqvist crack formation. Zirconia transformation was only observed in the plastically deformed zones underneath the imprints whereas there were significant residual compressive stresses outside the plastic zones due to the indentation damage. The intensity of this residual compressive field was dependent on the level of zirconia transformation due to indentation damage because zirconia transformation induced tensile stress fields superimposed on the compressive stresses. 相似文献
106.
Paula Altesor Carmen Rossini Paulo H.G. Zarbin Andrés González 《Journal of chemical ecology》2009,35(3):349-354
Epinotia aporema (Walsingham) is a Neotropical pest of legumes in southern South America. Its importance has increased during the last decade
owing to the significant growth of soybean production in the region. Monitoring of E. aporema is difficult due to the cryptic behavior of the larvae, and hence, chemical control is carried out preventively. We analyzed
the female-produced sex pheromone so as to develop monitoring traps and explore pheromone-based control methods. We analyzed
pheromone gland extracts by combined chromatographic, spectrometric, and electrophysiological methods. Based on the comparison
of retention indices, mass spectra, and electroantennogram (EAD) activity of the insect-produced compounds with those of synthetic
standards, we identified two EAD-active compounds, (Z,Z)-7,9-dodecadienol and (Z,Z)-7,9-dodecadienyl acetate (15:1 ratio), as sex pheromone components of E. aporema. We also studied the behavior of males in wind tunnel tests using virgin females and different combinations of synthetic
standards (15:1, 1:1, and 1:0 alcohol/acetate) as stimuli. A significantly greater percentage of males reached the chemical
source with the 15:1 synthetic mixture than with any of the other treatments, indicating that these two compounds are pheromone
components.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
107.
Franco Fernndez Generosa Gmez Carmen Lpez Ana Santos 《Advanced Synthesis \u0026amp; Catalysis》1989,331(1):15-21
Friedel-Crafts acetylation of phenanthrene ( 1a ) in sym-tetrachloroethane yields mixtures of 2-, 3- and 9-acetylphenanthrenes ( 2a, 3a, 4 ). The distribution of isomers is found to depend strongly upon the method of mixing the reagents. Acetylation of 9-chlorophenanthrene ( 1b ), performed by a variety of methods and solvents, led mainly to 3-acetyl-9-chlorophenanthrene ( 3b ) (≥85%). Previously unreported 2-acetyl-9-chlorophenanthrene ( 2b ) was found to form up to a maximum 11% in nitrobenzene. 相似文献
108.
Beatriz de Rivas Rubn Lpez-Fonseca Carmen Sampedro Jos I. Gutirrez-Ortiz 《Applied catalysis. B, Environmental》2009,90(3-4):545-555
In the present paper the thermal deactivation of a series of Ce/Zr mixed oxides (CeO2, Ce0.8Zr0.2O2, Ce0.68Zr0.32O2, Ce0.5Zr0.5O2, Ce0.15Zr0.85O2 and ZrO2) was investigated. In order to simulate long-term operation, samples were calcined at three different temperatures, namely 550, 750 and 1000 °C in air for 4 h. Structural, morphological and physico-chemical changes caused by high-temperature treatment were analysed by X-ray diffraction, BET measurements, NH3-temperature-programmed desorption and temperature-programmed reduction with hydrogen, and the behaviour in the oxidation of chlorinated volatile organic compounds (1,2-dichloroethane and trichloroethylene). The catalytic properties of Ce/Zr mixed oxides could be accounted for on the basis of their promoted redox, as characterised by the percentage of oxygen vacancies, and acidic properties due to the incorporation of zirconium in the ceria lattice. An increase in the calcination temperature led to a progressive decrease in the catalytic activity as a result of the modifications provoked by induced thermal aging (decrease in surface area, larger crystal sizes, reducibility at higher temperatures and loss of acid sites). Ce0.15Zr0.85O2 and Ce0.5Zr0.5O2 showed the best resistance to deactivation with combustion temperatures still notably lower in comparison with the homogeneous reaction even after calcination at 1000 °C. Also slight changes in selectivity were evident resulting in favoured yields of hydrogen chloride, which was environmentally beneficial, and incomplete combustion products such as carbon monoxide and chlorinated intermediates. 相似文献
109.
Tania Castaño Dr. Huanchen Wang Dr. Nuria E. Campillo Dr. Sara Ballester Dr. Coral González‐García Javier Hernández Concepción Pérez Dr. Jimena Cuenca Dr. Ana Pérez‐Castillo Prof. Ana Martínez Prof. Oscar Huertas José Luis Gelpí Prof. F. Javier Luque Prof. Hengming Ke Prof. Carmen Gil Dr. 《ChemMedChem》2009,4(5):866-876
PDE7 inhibitors regulate pro‐inflammatory and immune T‐cell functions, and are a potentially novel class of drugs particularly useful for treatment of a wide variety of immune and inflammatory disorders. Structural optimization of thioxoquinazoline derivatives led to new compounds with very interesting profiles as PDE7 or PDE7/PDE4 dual inhibitors, which may be further developed as new drugs for inflammatory and neurological diseases.
110.
Dolomite reacts with H2S to produce calcium sulphide and has been broadly investigated as a desulphurisation agent due to its low-cost and favourable properties.Because CaS reacts with water or water vapour in the environment to regenerate hydrogen sulphide and, therefore, disposal is problematic and the chemical cannot be uses as a landfill material. One of the methods used to make this material inert is oxidation to convert calcium sulphide into calcium sulphate or calcium oxide.In our study, tests were carried out using dolomite from Granada, Spain, that was previously calcined and sulphurised at high temperature with a gas similar to that produced in gasification facilities. To approximate real-scale results, a relatively large amount of substance was used for each sample (100–150 g) and the samples were used in a fixed-bed position.The influence of different conditions, such as grain size, composition of the oxidation gas, gas velocity, bed length and temperature, was them investigated. The final solid products were characterised by X-ray diffraction and chemical analysis and the CO2, SO2, H2S and COS concentrations in the gases produced during oxidation were analysed by gas chromatography.The results showed that the most influential factor was grain size and that the best oxidant was O2 mixed with nitrogen.The presence of water vapour increases the residual concentration of CaS in the end product, but increased the CaO contentThe higher the oxygen concentration and the higher the gas velocity, the lower the residual content of CaS. CO2 used alone oxidises CaS to produce SO2 and COS, but at very low rates. It also produces some CS2. Water vapour used alone can also oxidise the CaS to produce H2S and SO2 but also at very low velocity.At higher oxidation temperature, between 700°C and 850 °C, lesser residual CaS is obtained in the oxidised product. 相似文献