6,907 research outputs found
Single Stellar Populations in the Near-Infrared - I. Preparation of the IRTF spectral stellar library
We present a detailed study of the stars of the IRTF spectral library to
understand its full extent and reliability for use with Stellar Population (SP)
modeling. The library consist of 210 stars, with a total of 292 spectra,
covering the wavelength range of 0.94 to 2.41 micron at a resolution R = 2000.
For every star we infer the effective temperature (Teff), gravity (logg) and
metallicity ([Z/Zsun]) using a full-spectrum fitting approach in a section of
the K band (2.19 to 2.34 micron) and temperature-NIR colour relations. We test
the flux calibration of these stars by calculating their integrated colours and
comparing them with the Pickles library colour-temperature relations. We also
investigate the NIR colours as a function of the calculated effective
temperature and compared them in colour-colour diagrams with the Pickles
library. This latter test shows a good broad-band flux calibration, important
for the SP models. Finally, we measure the resolution R as a function of
wavelength. We find that the resolution increases as a function of lambda from
about 6 angstrom in J to 10 angstrom in the red part of the K-band. With these
tests we establish that the IRTF library, the largest currently available
general library of stars at intermediate resolution in the NIR, is an excellent
candidate to be used in stellar population models. We present these models in
the next paper of this series.Comment: 17 pages, 19 figures. Accepted for publication in Astronomy and
Astrophysic
Concrete retrofitting using CFRP and geopolymer mortars
A new development in the repair and strengthening of reinforced concrete systems is the use of carbon fiber reinforced polymers (CFRP) strips bonded to concrete substrate with epoxy
resins. It has been reported that epoxy adhesive are extremely sensitive to high temperatures. Some authors conclude that the epoxy temperature should not exceed 70 ÂşC in order to safeguard the adhesiveness of the epoxy and, thus, the integrity and adequate functioning of CFRP. It is noted that even frequently exposure to direct sunlight causes temperatures higher than 70 ÂşC. Since geopolymers are known to possess high stability at high temperature, these materials can be an
alternative to epoxy resins. This papers presents results about the use of metakaolin based geopolymers mortars to insure the adhesion between the CFRP and the concrete substrate. Several compositions of geopolymer mortars were executed by varying the percentage of binder, sand/binder ratio and the concentration of sodium hydroxide. It was found that geopolymer mortars demonstrate very promising performances, having obtained a high mechanical resistance and a good adhesion to concrete. On the other hand the adhesion between CFRP and geopolymer mortars proved to be smaller than expected which could be due, to the fact that the composition of the mortar was not optimized or even to the nature of the CFRP
Concrete retrofitting using metakaolin geopolymer mortars and CFRP
This paper presents results about the use of metakaolin based geopolymers mortars for retrofitting purposes. Two main situations are addressed, the use of geopolymeric mortars as a repairing layer or as a binding agent to insure the adhesion between CFRP sheets and the concrete substrate. Several compositions of metakaolin geopolymer mortars were executed by varying the percentage of sand/binder mass ratio and the concentration of sodium hydroxide. It was found that metakaolin geopolymer mortars show a high mechanical resistance and a relevant adhesion to the concrete substrate. Although their adhesion strength is lower than the one present by commercial pre-pack repair mortars, they are very cost-effective (5 to 10 times less expensive). On the other hand, the adhesion strength between CFRP and geopolymer mortars proved to be lower than expected which could be due to the fact that the composition of the geopolymeric mortars was not optimized and also to the fact that the CFRP used was not prone to this kind of application
Herbicidal activity of volatiles from coriander, winter savory, cotton lavender, and thyme isolated by hydrodistillation and supercritical fluid extraction
The volatiles from Coriandrum sativum L., Satureja montana L., Santolina chamaecyparissus L., and Thymus vulgaris L. were isolated by hydrodistillation (essential oil) and supercritical fluid extraction (volatile oil). Their effect on seed germination and root and shoot growth of the surviving seedlings of four crops (Zea mays L., Triticum durum L., Pisum sativum L., and Lactuca sativa L.) and two weeds (Portulaca oleracea L. and Vicia sativa L.) was investigated and compared with those of two synthetic herbicides, Agrocide and Prowl. The volatile oils of thyme and cotton lavender seemed to be promising alternatives to the synthetic herbicides because they were the least injurious to the crop species. The essential oil of winter savory, on the other hand, affected both crop and weeds and can be appropriate for uncultivated fields
Skin Disease in Liver and Kidney Transplant Recipients Referred to the Department of Dermatology and Venereology
Introdução: Foram descritas várias doenças cutâneas em doentes transplantados, em relação com a terapêutica imunossupressora
instituĂda. Pretendemos caracterizar o espectro clĂnico das patologias dermatolĂłgicas e comparar os diagnĂłsticos entre os doentes transplantados hepáticos e os doentes transplantados renais.
Material e MĂ©todos: Estudo descritivo e retrospectivo atravĂ©s da consulta de processos clĂnicos de todos os doentes submetidos a transplante hepático ou renal entre 2000 - 2010 referenciados Ă Consulta de Dermatologia e Venereologia.
Resultados: Observámos 319 doentes transplantados (23,5%) e apurámos 410 diagnĂłsticos (230 na sub-população com transplante hepático e 180 na sub-população com transplante renal), divididos em quatro grupos: 1) infecções cutâneas; 2) cancro cutâneo ou lesões precursoras; 3) manifestações cutâneas relacionadas com efeitos secundários de fármacos; 4) outras patologias dermatolĂłgicas nĂŁo iatrogĂ©nicas. As infecções cutâneas foram as mais observadas (42,2%), em mĂ©dia 32,7 meses apĂłs o transplante. Este grupo incluiu 20,5% de infecções fĂşngicas, 12,7% virais e 8,5% bacterianas. Identificámos patologia tumoral e lesões precursoras em 11,7% dos casos, em mĂ©dia 44,8 meses apĂłs o transplante e assumindo maior importância na sub-população com transplante renal (20,6% vs 4,8% nos transplantados hepáticos; P < 0,001). Os transplantados renais apresentaram predomĂnio de carcinomas espinocelulares
(CEC) sobre os casos de carcinomas basocelulares (CBC), numa razão CEC:CBC de 1,3:1 mas nos transplantados hepáticos verificou-se uma razão CBC: carcinomas de 3,5:1. Ocorreram efeitos secundários de fármacos em 10,5% dos casos e outras patologias dermatológicas não iatrogénicas em 35,6%.
Discussão: Apesar da patologia tumoral ser a mais referida na literatura, as infecções cutâneas foram as mais observadas na nossa
amostra. As diferenças significativas entre as duas sub-populações estudadas podem estar relacionadas com o maior grau de imunossupressão a que os doentes transplantados renais estão sujeitos.
Conclusão: Dada a elevada frequência de patologia cutânea nestes doentes é essencial incluir o acesso a consultas de Dermatologia
e Venereologia nos cuidados multi-disciplinares pĂłs-transplante
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