944 resultados para lability of metal species
Resumo:
Observations on maturation stages of nineteen species of economically important finfish off the Northeast coast of the USA were analyzed to examine relationships between fish size or age, and maturity. Maturation schedules and median lengths (L50) and ages (A50) at maturation were derived by fitting the logistic model to the observed proportions. Analyses were generally restricted to observations from 1985 to 1990 obtained during stratified random bottom trawl surveys conducted in spring and autumn by the Northeast Fisheries Science Center and the Commonwealth of Massachusetts Division of Marine Fisheries in waters of the continental shelf from Nova Scotia to Cape Hatteras, North Carolina. Butterfish, Peprilus triacanthus, attained sexual maturity at the smallest median length (11.4 cm, males) and pollock, Pollachius virens, at the highest (41.8 em, males). Median length at maturity for gadiforms ranged from 22.2 to 41.8 em. Within the pleuronectiforms, median length at maturity ranged from 19.1 to 30.4 cm. Median lengths for the pelagic and miscellaneous demersal species were in the same ranges as the pleuronectiforms. Butterfish also attained sexual maturity at the youngest median age (0.9 yr, both sexes) whereas redfish, Sebastes fasciatus, were the latest to mature (5.5 yr, both sexes). For gadids, the median age at maturity ranged from 1.3 to 2.3 yr. Within the pleuronectiforms, median age at maturity ranged from 1.3 to 4.4 yr and, for pelagic species, from 0.9 to 3.0 yr. Median lengths and ages for many species are lower than those reported in earlier studies of the same general region of the Northwest Atlantic. (PDF file contains 72 pages.)
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We present data on ichthyoplankton distribution, abundance, and seasonality and supporting environmental information for four species of coastal pelagics from the family Carangidae: blue runner Caranx crysos, Atlantic bumper Chloroscombrus chrysurus, round scad Decapterus punctatus, and rough scad Trachurus lathami. Data are from 1982 and 1983 cruises off Louisiana sponsored by the Southeastern Area Monitoring and Assessment Program (SEAMAP). Bioprofiles on reproductive biology, early life history, meristics, adult distribution, and fisheries characteristics are also presented for these species. Maximum abundances of larval blue runner, Atlantic bumper, and round scad were found in July inside the 4O-m isobath, although during the rest of the cruises these species were rarely found together. Larval Atlantic bumper were captured in June and July only; blue runner in May, June, and July; and round scad in all seasons. Atlantic bumper larvae, concentrated mostly off western Louisiana, were by far the most abundant carangid in 1982 and 1983. Larval blue runner were the second most abundant summer-spawned carangid in 1982 and 1983, but their abundance and depth distribution varied considerably between years. Relative abundance of larval round scad off Louisiana was low, and they were captured only west of the Mississippi River delta, although they are reported to dominate carangid populations in the eastern Gulf of Mexico. Rough scad were primarily winter/spring and outer-shelf (40-182 m) spawners. They ranked third in overall abundance, but were the most abundant target carangid on the outer shelf. Ecological parameters such as surface salinity, temperature, and station depth are presented from capture sites for recently hatched larvae <2.5 mm notochord length, except round scad) as well as for all sizes of fish below 14 mm standard length. (PDF file contains 44 pages.)
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We present data on ichthyoplankton distribution, abundance, and seasonality and supporting environmental information for four species of coastal pelagics from the family Clupeidae: round herring Etrumeus teres, scaled sardine Harengula jaguana, Atlantic thread herring Opisthonema oglinum, and Spanish sardine Sardinella aurita. Data are from 1982 and 1983 cruises across the northern Gulf of Mexico sponsored by the Southeastern Area Monitoring and Assessment Program (SEAMAP). This is the first such examination for these species on a multiyear and gulfwide scale. Bioproflles on reproductive biology, early life history, meristics, adult distribution, and fisheries characteristics are also presented for these species. During the summer, larval Atlantic thread herring and scaled and Spanish sardines were abundant on the inner shelf <40 m depth), but were rare or absent in deeper waters. Scaled sardine and thread herring were found virtually everywhere inner-shelf waters were sampled, but Spanish sardines were rare in the north-central Gulf. During 1982, larval Atlantic thread herring were the most abundant of the four target c1upeid species, whereas Spanish sardine were the most abundant during 1983. On the west Florida shelf, Spanish sardine dominated larval c1upeid populations both years. Scaled sardine larvae were the least abundant of the four species both years, but were still captured in 25% of inner-shelf bongo net collections. Round herring larvae, collected February-early June (primarily March-April), were abundant on the outer shelf (40-182 m depth) and especially off Louisiana. Over the 2-year period, outer-shelf mean abundance for round herring was 40.2 larvae/10 m2; inner-shelf mean abundances for scaled sardine, Atlantic thread herring, and Spanish sardine were 14.9, 39.2, and 41.9 larvae/l0 m2, respectively. (PDF file contains 66 pages.)
Resumo:
The moisture, fat, ash, fatty acid profile, and cholesterol content are reported for cooked and raw fillets from 22 species of finfish found in the Northwest Atlantic. All but nine species had 1%or less fat. Ocean perch and a spring sampling of mackerel and wolffiSh had about 2% fat, followed by yellowfin tuna, whiting, silver hake, butterfish, and a summer -sampling of mackerel and wolffish with a range of 3-7% fat. Herring had a range of 5-12% fat representing a winter sampling on the low end and summer sampling on the high end of the range. Bluefin tuna (a summer sampling) contained the most fat with a high of 23% fat. Omega-3 fatty acids were present in excess of omega-6 fatty acids. The fattier fISh supplied the most omega-3 fatty acids per gram of tissue. The mean cholesterol content for all species was 57 ± 16 mg/l00 g raw tissue. Finfish from the Northwest Atlantic would appear to fit into the regime for a healthy heart, being low in fat and cholesterol and rich in omega-3 fatty acids.(PDF file contains 42 pages.)
Resumo:
The United States and Japanese counterpart panels on aquaculture were formed in 1969 under the United States-Japan Cooperative Program in Natural Resources (UJNR). The panels currently include specialists drawn from the federal departments most concerned with aquaculture. Charged with exploring and developing bilateral cooperation, the panels have focused their efforts on exchanging information related to aquaculture which could be of benefit to both countries. The UJNR was begun during the Third Cabinet-Level Meeting of the Joint United States-Japan Committee on Trade and Economic Affairs in January 1964. In addition to aquaculture, current subjects in the program include desalination of seawater, toxic microorganisms, air pollution, energy, forage crops, national park management, mycoplasmosis, wind and seismic effects, protein resources, forestry, and several joint panels and committees in marine resources research, development, and utilization. Accomplishments include: Increased communication and cooperation among technical specialists; exchanges of information, data, and research findings; annual meetings of the panels, a policy-coordinative body; administrative staff meetings; exchanges of equipment, materials, and samples; several major technical conferences; and beneficial effects on international relations. (PDF file contains 79 pages.)
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A method of identifying the beaks and estimating body weight and mantle length of 18 species of cephalopods from the Pacific Ocean is presented. Twenty specimens were selected from each of the following cephalopod species: Symplectoteuthis oualaniensis, Dosidicus gigas, Ommastrephes bartramii, S. luminosa, Todarodes pacificus, Nototodarus hawaiiensis, Ornithoteuthis volalilis, Hyaloteuthis pelagica, Onychoteuthis banksii, Pterygioteuthis giardi, Abraliopsis affinis, A. felis, Liocranchia reinhardti, Leachia danae, Histioteuthis heteropsis, H. dofleini, Gonalus onyx, and Loligo opalescens. Dimensions measured on the upper and lower beak are converted to ratios and compared individually among the species using an analysis of variance procedure with Tukey's omega and Duncan's multiple range tests. Significant differences (P =0.05) observed among the species' beak ratio means and structural characteristics are used to construct artificial keys for the upper and lower beaks of the 18 species. Upper and lower beak dimensions are used as independent variables in a linear regression model with mantle length and body weight (log transformed). (PDF file contains 56 pages.)
Resumo:
A simple derivation based on continuum mechanics is given, which shows the surface stress is critical for yield strength at ultra-small scales. Molecular dynamics (MD) simulations with modified embedded atom method (MEAM) are employed to investigate the mechanical behaviors of single-crystalline metal nanowires under tensile loading. The calculated yield strengths increasing with the decrease of the cross-sectional area of the nanowires are in accordance with the theoretical prediction. Reorientation induced by stacking faults is observed at the nanowire edge. In addition. the mechanism of yielding is discussed in details based on the snapshots of defects evolution. The nanowires in different crystallographic orientations behave differently in stretching deformation. This study on the plastic properties of metal nanowires will be helpful to further understanding of the mechanical properties of nanomaterials. (C) 2009 Elsevier B.V. All rights reserved.
Resumo:
The effects of some environmental factors on the fecundity of Tilapia species (Family Cichilidae) was carried out at the Kigera dam. Four Tilapia species caught were Tilapia zilli, Hemichromis fasciatus, Sarotherodon galilaeus and Oreochromis niloticus while the environmental factors considered were water temperature, Dissolved Oxygen, pH value, level of rainfall and rate of sunshine and range of time. 43 fish comprising of 25 male with (58.1%) and 18 females having (41.9%) were studied with 74.42% been sexually matured. Both high levels of rainfall and dissolved oxygen favoured fecundity. The spawning peak occurred in (July), environmental factors monitored indicated that dissolved oxygen ranges from 3.7 to 4.45mg/lit rainfall ranges from (34.90mm to 237.80mm) sunshine ranges from (5hrs-8hrs) and pH ranges from (7.35-7.45). The spawning of these species in their natural or hatchery condition is therefore best achieved during the peak of raining season
Resumo:
Eudiaptomus vulgaris Schmeil is the most abundant copepod in Lake Maggiore and forms also, in respect to other entomostraca, the most important element, through its average biomass and because it is fairly numerous throughout the year. Plankton samples collected in a systematic and quantitative way, gave the opportunity to study some aspects of the dynamics of the population of this copepod, in safety in view of the uncertainty which in this kind of study can ensue when samples are taken only at a single station - in consequence of the changes in size of population between different water masses. The results of the biometrical observations are of the population of Eudiaptomus vulgaris is presented.
Resumo:
This thesis describes applications of cavity enhanced spectroscopy towards applications of remote sensing, chemical kinetics and detection of transient radical molecular species. Both direct absorption spectroscopy and cavity ring-down spectroscopy are used in this work. Frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) was utilized for measurements of spectral lineshapes of O2 and CO2 for obtaining laboratory reference data in support of NASA’s OCO-2 mission. FS-CRDS is highly sensitive (> 10 km absorption path length) and precise (> 10000:1 SNR), making it ideal to study subtle non-Voigt lineshape effects. In addition, these advantages of FS-CRDS were further extended for measuring kinetic isotope effects: A dual-wavelength variation of FS-CRDS was used for measuring precise D/H and 13C/12C methane isotope ratios (sigma>0.026%) for the purpose of measuring the temperature dependent kinetic isotope effects of methane oxidation with O(1D) and OH radicals. Finally, direct absorption spectroscopic detection of the trans-DOCO radical via a frequency combs spectrometer was conducted in collaboration with professor Jun Ye at JILA/University of Colorado.
Resumo:
A novel metallized azo dye has been synthesized. The absorption spectra of the thin film and thermal characteristic are measured. Static optical recording properties with and without the Bi mask layer super-resolution near-field structure (Super-RENS) of the metal-azo dye are investigated. The results show that the metal-azo dye film has a broad absorbance band in the region of 450-650 nm and the maximum absorbance wavelength is located at 603 nm. It is also found that the new metallized azo dye occupies excellent thermal stability, initiatory decomposition temperature is at 270 degrees C and the mass loss is about 48% in a narrow temperature region (15 degrees C). The complex refractive index N (N = n + ik) is measured. High refractive index (n = 2.45) and low extinction coefficient (k = 0.2) at the recording wavelength 650nm are attained. Static optical recording tests with and without Super-RENS are carried out using a 650nm semiconductor diode laser with recording power of 7mW and laser pulse duration of 200ns. The AFM images show that the diameter of recording mark on the dye film with the Bi mask layer is reduced about 42%, compared to that of recorded mark on the dye film without Super-RENS. It is indicated that Bi can well performed as a mask layer of the dye recording layer and the metallized azo dye can be a promising candidate for recording media with the super-resolution near-field structure.