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971.
Elaine Cristina Azevedo Gilberto Orivaldo Chierice Salvador Claro Neto Daniel Scheidegger Soboll Eduardo Mauro Nascimento Carlos Mauricio Lepienski 《辐射效应与固体损伤》2013,168(3):208-214
In this study, an adhesive of a polyurethane derivate from castor oil was irradiated with gamma radiation from a 60Co source, at doses from 0.2 to 25 kGy. This adhesive polyurethane is considered for use in hospital furniture because it does not liberate dangerous solvents. Hardness and elastic modulus were measured by instrumented indentation with a pyramidal Berkovich indenter, using loads from 0.08–40 mN with a nanoindenter XP. The instrumented indentation hardness was 110 MPa for an untreated sample, increasing to 124 MPa after irradiation with 25 kGy, at penetration depths of about 5 μm. The increases in elastic modulus induced by radiation were less pronounced. This polyurethane is naturally cross-linked and the relative modifications in the hardness are attributed to an additional cross-linking process induced by radiation. X-ray diffraction indicates a slight increase in crystallinity. The roughness measured by atomic force microscopy increases after gamma irradiation. 相似文献
972.
973.
Silvina C. Carretero Cristina Dapeña Eduardo E. Kruse 《Isotopes in environmental and health studies》2013,49(3):399-419
This contribution presents the hydrochemical and isotopic characterisation of the phreatic aquifer located in the Partido de la Costa, province of Buenos Aires, Argentina. In the sand-dune barrier geomorphological environment, groundwater is mainly a low-salinity Ca-HCO3 and Na-HCO3-type, being in general suitable for drinking, whereas in the continental plain (silty clay sediments), groundwater is a Na-Cl type with high salinity and unsuitable for human consumption. The general isotopic composition of the area ranges from?6.8 to?4.3 ‰ for δ18O and from?39 to?21 ‰ for δ2H, showing that rainwater rapidly infiltrates into the sandy substrate and reaches the water table almost without significant modification in its isotopic composition. These analyses, combined with other chemical parameters, made it possible to corroborate that in the eastern area of the phreatic aquifer, there is no contamination from marine salt water. 相似文献
974.
Robinson I. Roacho Alejandro J. Metta‐Magaña Eduardo Peña‐Cabrera Keith H. Pannell 《Journal of Physical Organic Chemistry》2013,26(4):345-351
Fluorescent members of the 4, 4‐difluoro‐4‐bora‐3a, 4a‐diaza‐s‐indacene (BODIPY) family are widely used for a range of markers, dyes, and sensors. The capacity to substitute the basic framework is an attractive feature permitting a range of differently substituted materials to be formed. New isomeric BODIPYs, o‐, m‐, and p‐8‐[R‐C6H4]‐BODIPY (R = CH2OH, 2a (o), 2b (m), 2c (p); R = OMe, 3a (o), 3b (m), 3c (p)), have been synthesized and characterized by nuclear magnetic resonance, absorbance and emission spectroscopy, and single crystal X‐ray diffraction. The o‐isomers have a very high quantum yield emission in non‐polar solvents, while the m‐ and p‐ analogs showed weak fluorescence under the same conditions. Spectroscopic analysis, as well as X‐ray structural characterization, suggested that substitution in the ortho‐position of the phenyl ring is sufficient to increase the steric hindrance and hence impede the rotation of the phenyl moiety about the 8C‐C axis, thereby favoring radiative compared to non‐radiative relaxation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
975.
The finite element based approximation of a quasilinear elliptic equation of non monotone type with Neumann boundary conditions
is studied. Minimal regularity assumptions on the data are imposed. The consideration is restricted to polygonal domains of
dimension two and polyhedral domains of dimension three. Finite elements of degree k ≥ 1 are used to approximate the equation. Error estimates are established in the L
2(Ω) and H
1(Ω) norms for convex and non-convex domains. The issue of uniqueness of a solution to the approximate discrete equation is
also addressed. 相似文献
976.
González Álvarez J Blanco Gomis D Arias Abrodo P Díaz Llorente D Busto E Ríos Lombardía N Gotor Fernández V Gutiérrez Álvarez MD 《Analytical and bioanalytical chemistry》2011,400(5):1209-1216
Two ionic liquids (ILs), namely (S,S)-1-butyl-3-(2'-hydroxy-cyclohexyl)-3H-imidazol-1-ium tetrafluoroborate and (S,S)-1-butyl-3-(2'-acetyl-cyclohexyl)-3H-imidazol-1-ium tetrafluoroborate have been employed as stationary phases in capillary gas chromatography. These new phases exhibit a column efficiency of 1,600 and 2,100 plates m(-1) for IL 1 and IL 2, respectively, a wide operating temperature range and good thermal stability (bleeding temperature of 250 °C for IL 1 and 160 °C for IL 2). Inverse gas chromatography (GC) analyses were used to study the solvation properties of these ILs through a linear solvation energy model. The application of these ILs as new GC stationary phases was studied. These stationary phases exhibited unique selectivity for many organic substances, such as alkanes, ketones, esters, and aromatic compounds. The efficient separation of several mixtures containing compounds of different polarities and the good separation of fatty acid methyl esters (FAMEs) and cis/trans isomers indicate that these ILs may be applicable as a new type of GC stationary phases. 相似文献
977.
Eduardo Hernández Michelle Pierri Maria Aparecida Bená 《Applied mathematics and computation》2011,217(22):8963-8972
We study the existence of asymptotically almost periodic classical solutions for a class of abstract neutral integro-differential equation with unbounded delay. A concrete application to partial neutral integro-differential equations which arise in the study of heat conduction in fading memory material is considered. 相似文献
978.
We derive a satisfying rate of convergence of the Marcus-Lushnikov process towards the solution to Smoluchowski’s coagulation equation. Our result applies to a class of homogeneous-like coagulation kernels with homogeneity degree ranging in (−∞,1]. It relies on the use of a Wasserstein-type distance, which has shown to be particularly well-adapted to coalescence phenomena. It was introduced and used in preceding works (Fournier and Laurençot (2006) [7]) and (Fournier and Löcherbach (2009) [8]). 相似文献
979.
Montico F Hetzl AC Cândido EM Fávaro WJ Cagnon VH 《Micron (Oxford, England : 1993)》2011,42(6):642-655
Hormonal replacement has been utilized to minimize the harmful effects of hormonal imbalance in elderly men. The development and progression of prostatic diseases and their relation to hormone therapy is still unclear. Thus, the aim herewith was to characterize the structure and dystroglycan molecule (DGs) reactivities in the ventral prostatic lobe from elderly rats submitted to steroid hormone replacement. Male rats (Sprague-Dawley) were divided into one Young group and six senile groups. The Young group (YNG) (4 months old) received peanut oil (5mL/kg, s.c.). The senile rats (10 months old) were submitted to the following treatments: Senile group (SEN) (5mL/kg peanut oil, s.c.); Testosterone group (TEST) (5mg/kg testosterone cipionate, s.c.); Estrogen group (EST) (25μg/kg 17β-estradiol, s.c.); Castrated group (CAS) (surgical castration); Castrated-Testosterone (CT) (surgical castration and treatment similar to TEST group); and Castrated-Estrogen (CE) (surgical castration and treatment similar to EST group). After 30 days treatment, blood samples were collected for hormonal analysis and ventral prostate samples were processed for light and transmission electron microscopies, morphometrical analysis, immunohistochemistry and Western Blotting. The results showed decreased serum testosterone levels in the senescence and increased testosterone and estrogen plasmatic levels after hormone administration in the TEST and EST groups, respectively, highlighting the therapy efficiency. Hypertrophied stroma and inflammatory cells were verified in the SEN group. After hormone replacement in the senescence or following castration, atrophic epithelium, epithelial cells with clear cytoplasmic halo around the nucleus, microacini and maintenance of hypertrophied stroma were seen. Decreased DG levels were verified in the senescence. After hormonal therapy, increased protein levels of these molecules were observed, especially in those groups which received estradiol. Thus, the occurrence of inflammatory cells, stromal hypertrophy and the presence of cells with clear halo around the nucleus after hormonal therapy probably indicated prostatic paracrine signaling imbalance, suggesting a stromal reactive microenvironment favorable to the development of glandular lesions. However, the increase of DG levels characterized positive effect of steroid hormone replacement on the prostate in the senescence. Thus, it could be concluded that despite having positive effects on important molecules involved in the maintenance of epithelial-stromal interaction and glandular cytoarchitecture, such as DGs, hormonal therapy enhanced structural changes associated with senescence, probably due to increased hormonal imbalance between androgens and estrogens in the prostatic tissue. 相似文献
980.
Eduardo Zapp Daniela Brondani Iolanda C. Vieira Jairton Dupont Carla W. Scheeren 《Electroanalysis》2011,23(3):764-776
A matrix comprising iridium nanoparticles and 1‐butyl‐3‐methylimidazolium tetrafluoroborate ionic liquid (Ir‐BMI.BF4) supported in montmorillonite (MMT) was obtained through an efficient incorporation process. This modified clay matrix (Ir‐BMI.BF4‐MMT) was used for the immobilization of the enzymes laccase (LAC) and polyphenol oxidase (PPO) and employed in the construction of a bi‐enzymatic biosensor for determination of rutin by square‐wave voltammetry. Under optimized conditions, the analytical curve showed a linear range for rutin concentrations from 9.17×10?8 to 3.10×10?6 mol L?1 with a detection limit of 3.09×10?8 mol L?1. The method was successfully applied to the determination of rutin content in pharmaceutical samples. 相似文献