Effect of processing parameters on the optical properties of TiO2/ormosil planar waveguide

Hybrid TiO2/ormosil waveguiding films have been prepared by the sol-gel method at low thermal treatment temperature of 150° C. The influence of processing parameters including the molar ratios of titanium butoxide (Ti(OBu)(4))/3-glycidoxypropyltrimethoxysilane (GLYMO) and H2O/Ti(OBu)(4) (expressed as R), especially aging of sot on the optical properties was investigated. The optical properties of films were measured with scanning electron microscope (SEM), UV/VIS/NIR spectrophotometer (UV-Vis), m-line and the scattering-detection method. The results indicate that the film thickness increases with the increase of sol aging time, but the variation of refractive index as a function of sot aging time depends on the relative ratios of GLYMO to Ti(OBu)(4). Higher transmittance and lower attenuation of the planar waveguide can be obtained in the sol with lower Ti(OBu)(4) contents and shorter aging time.

Cultura de tecidos e análise do potencial antioxidante de Passiflora alata Curtis

Passiflora alata Curtis, comumente conhecida como maracujá-doce, é uma das espécies do gênero Passiflora cultivadas comercialmente, sendo consumida in natura devido ao seu gosto adocicado. Ela também é utilizada em todo o mundo como ornamental e na medicina popular. O objetivo deste trabalho foi o estabelecimento de diferentes estratégias para a cultura in vitro de P. alata e a análise da produção de substâncias antioxidantes nos materiais obtidos in vitro, em comparação com as plantas in vivo. Diferentes tratamentos visando à quebra da dormência das sementes foram avaliados para a germinação in vitro ou in vivo, além da incubação das sementes sob tipos distintos de luz. Para o estabelecimento das culturas primárias, apices caulinares e segmentos nodais das plântulas derivadas da germinação in vitro foram cultivados em meio MSM . A taxa de alongamento dos brotos e o número de nós por brotos das culturas primárias foram aumentados pela adição de água de coco ao meio. Plantas derivadas dessas culturas foram utilizadas como fontes de explantes nodais, internodais e foliares. O potencial morfogênico de sementes sem tegumento foi também avaliado. Calos friáveis foram induzidos a partir de segmentos nodais e foliares na presença de PIC, e aqueles obtidos a partir de folhas em meio suplementado com PIC a 28,9 μM foram selecionados para o estabelecimento de culturas de células em suspensão. Após o desenvolvimento de diferentes estratégias in vitro para P. alata, folhas de plantas in vivo foram utilizadas para a avaliação de parâmetros que afetam a extração de substâncias antioxidante. O potencial antioxidante foi determinado pelo ensaio DPPH e o conteúdo de fenóis totais foi determinado utilizando o método Folin-Ciocalteau. Após o desenvolvimento do protocolo de extração, a atividade antioxidante dos diferentes materiais in vitro foi também avaliada. A eficiência antirradicalar variou entre os sistemas de cultura estudados, sendo diretamente proporcional ao conteúdo de fenóis totais dos extratos. Esses resultados indicam que as estratégias para cultura in vitro de P. alata desenvolvidas neste trabalho representam alternativas para a multiplicação de plantas e produção de substâncias fenólicas com ação antioxidante.

Estimation of the growth curve parameters in Macrobrachium rosenbergii

Growth is one of the most important characteristics of cultured species. The objective of this study was to determine the fitness of linear, log linear, polynomial, exponential and Logistic functions to the growth curves of Macrobrachium rosenbergii obtained by using weekly records of live weight, total length, head length, claw length, and last segment length from 20 to 192 days of age. The models were evaluated according to the coefficient of determination (R2), and error sum off square (ESS) and helps in formulating breeders in selective breeding programs. Twenty full-sib families consisting 400 PLs each were stocked in 20 different hapas and reared till 8 weeks after which a total of 1200 animals were transferred to earthen ponds and reared up to 192 days. The R2 values of the models ranged from 56 – 96 in case of overall body weight with logistic model being the highest. The R2 value for total length ranged from 62 to 90 with logistic model being the highest. In case of head length, the R2 value ranged between 55 and 95 with logistic model being the highest. The R2 value for claw length ranged from 44 to 94 with logistic model being the highest. For last segment length, R2 value ranged from 55 – 80 with polynomial model being the highest. However, the log linear model registered low ESS value followed by linear model for overall body weight while exponential model showed low ESS value followed by log linear model in case of head length. For total length the low ESS value was given by log linear model followed by logistic model and for claw length exponential model showed low ESS value followed by log linear model. In case of last segment length, linear model showed lowest ESS value followed by log linear model. Since, the model that shows highest R2 value with low ESS value is generally considered as the best fit model. Among the five models tested, logistic model, log linear model and linear models were found to be the best models for overall body weight, total length and head length respectively. For claw length and last segment length, log linear model was found to be the best model. These models can be used to predict growth rates in M. rosenbergii. However, further studies need to be conducted with more growth traits taken into consideration

Comparison of spectroscopic parameters of 15 at% Yb : YAlO3 and 15 at% Yb : Y3Al5O12

Yb: YAlO3 (YAP) (15 at %) and Yb: Y3Al5O12 (YAG)(15 at %) have been grown using the Czochralski method. Their absorption and fluorescence spectra were measured at room temperature and important spectroscopic parameters were calculated. Through the comparison of spectroscopic parameters of Yb:YAP and Yb: YAG, all results indicate that 15 at % Yb:YAP crystal is a potential candidate used for compact, efficient thin chip lasers when the laser output wavelength is 1012 or 103 8 nm. (C) 2004 Elsevier B.V. All rights reserved.

Effect of process parameters on laser damage threshold of TiO2 coatings

We investigate the laser damage behaviour of an electron-beam-deposited TiO2 monolayer at different process parameters. The optical properties, chemical composition, surface defects, absorption and laser-induced damage threshold (LIDT) of Elms are measured. It is found that TiO2 Elms with the minimum absorption and the highest LIDT can be fabricated using a TiO2 starting material after annealing. LIDT is mainly related to absorption and is influenced by the non-stoichiometric defects for TiO2 films. Surface defects show no evident effects on LIDT in this experiment.

Comparison of life history parameters for landed and discarded fish captured off the southeastern United States

Commercial fisheries that are managed with minimum size limits protect small fish of all ages and may affect size-selective mortality by the differential removal of fast growing fish. This differential removal may decrease the average size at age, maturation, or sexual transition of the exploited population. When fishery-independent data are not available, a comparison of life history parameters of landed with those of discarded fish (by regulation) will indicate if differential mortality is occurring with the capture of young but large fish (fast growing phenotypes). Indications of this differential size-selective mortality would include the following: the discarded portion of the target fish would have similar age ranges but smaller sizes at age, maturation, and sexual transition as that of landed fish. We examined three species with minimum size limits but different exploitation histories. The known heavily exploited species (Rhomboplites aurorubens [vermilion snapper] and Pagrus pagrus [red porgy]) show signs of this differential mortality. Their landed catch includes many young, large fish, whereas discarded fish had a similar age range and mean ages but smaller sizes at age than the landed fish. The unknown exploited species, Mycteroperca phenax (scamp), showed no signs of differential mortality due to size-selective fishing. Landed catch consisted of old, large fish and discarded scamp had little overlap in age ranges, had significantly different mean ages, and only small differences in size at age when compared to comparable data for landed fish.

Habitat and bycatch effects on population parameters of inshore lizardfish (Synodus foetens) in the north central Gulf of Mexico

We examined the effect of habitat and shrimp trawl bycatch on the density, size, growth, and mortality of inshore lizardfish (Synodus foetens), a nonexploited species that is among the most widespread and abundant benthic fishes in the north central Gulf of Mexico. Results of quarterly trawl sampling conducted from spring 2004 through spring 2005 revealed that inshore lizardfish are most abundant on sand habitat, but larger fish are more common on shell rubble habitat. There was no significant difference in fish density between habitats exposed to shrimp trawling on the open shelf versus those habitats within a permitted artificial reef zone that served as a de facto no-trawl area; this finding indicates that either inshore lizardfish experienced minimal effects from trawling or, more likely, that fish moved between trawled and nontrawled habitats. Exploitation ratio (bycatch mortality/total morality) estimates derived from catch curve analysis ranged from 0.43 inside the artificial reef zone to 0.55 outside the reef zone, thus indicating that inshore lizardfish are subject to significant fishing mortality in the north central Gulf of Mexico despite the lack of a directed fishery for the species. We infer from this result that effects of shrimp trawl bycatch may be significant at the population level for nonexploited species and that a broader ecosystem-scale examination of bycatch effects is warranted.

A comparison of length-related and age-related growth parameters of newaiby Otolithes ruber in Kuwait waters

The growth parameters of Otolithes ruber (Sciaenidae) were determined from both length-frequency and length-at-age data collected from Kuwait waters from 1984 to 1986. The similarity of the growth parameters is reflected in the small range of the parameters o' (=log sub(10)K+2logL) which indicates the compatibility of the two methods for this relatively short-lived species.