bluuebunny/crossref_metadata_2025 huggingface dataset:
The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario
Authors: Moecher David P. , Anderson Eric D. , Cook Claudia A. , Mezger Klaus
Published: October 2008

Veins and dikes of calcite-rich rocks within the Central Metasedimentary Belt boundary zone (CMBbz) in the Grenville Province of Ontario have been interpreted to be true carbonatites or to be pseudocarbonatites derived from interaction of pegmatite melts and regional Grenville marble. The putative carbonatites have been metamorphosed and consist mainly of calcite, biotite, and apatite with lesser amounts of clinopyroxene, magnetite, allanite, zircon, titanite, cerite, celestite, and barite. The rocks have high P and rare earth element (REE) contents, and calcite in carbonatite has elevated Sr, Fe, and Mn contents relative to Grenville Supergroup marble and marble mélange. Values of δ18OSMOW (9.9–13.3‰) and δ13CPDB (−4.8 to −1.9‰) for calcite are also distinct from those for marble and most marble mélange. Titanites extracted from clinopyroxene–calcite–scapolite skarns formed by metasomatic interaction of carbonatites and silicate lithologies yield U–Pb ages of 1085 to 1035 Ma. Zircon from one carbonatite body yields a U–Pb age of 1089 ± 5 Ma; zircon ages from two other bodies are 1170 ± 3 and 1143 ± 8 Ma, suggesting several carbonatite formation events or remobilization of carbonatite during deformation and metamorphism around 1080 Ma. Values of εNd(T) are 1.7–3.2 for carbonatites, −1.5–1.0 for REE-rich granite dikes intruding the CMBbz, and 1.6–1.7 for marble. The mineralogy and geochemical data are consistent with derivation of the carbonatites from a depleted mantle source. Mixing calculations indicate that interaction of REE-rich pegmatites with regional marbles cannot reproduce selected major and minor element abundances, REE contents, and O and Nd isotope compositions of the carbonatites.
Uppermost Wenlock and Ludlow graptolites from southern Yunnan, China
Authors: Zhang Yuan-Dong , Lenz Alfred C.
Published: October 2008

A diverse late Homerian and Ludlow graptolite fauna including 38 species is recognized from shales and claystones of Shuiqingliangzi section in Mojiang County, southern Yunnan, China. Two Wenlock and three Ludlow graptolite biozones are recognized, which, in ascending order, are Colonograptus praedeubeli Biozone, Colonograptus ludensis Biozone, Lobograptus progenitor Biozone, Lobograptus scanicus Biozone, and Saetograptus fritschi linearis Biozone. The 20 species described in the present paper comprise Plectograptus macilentus (Törnquist), Plectograptus sp., Agastograptus clathrospinosus (Eisenack), Agastograptus sp. 1, Agastograptus sp. 2, Gothograptus nassa (Holm), Neogothograptus sp., Colonograptus praedeubeli (Jaeger), Colonograptus ludensis (Murchison), Pseudomonoclimacis dalejensis (Bouček), Monograptus ex gr. uncinatus Tullberg, Monograptus sp., Saetograptus chimaera (Barrande), Saetograptus fritschi linearis (Bouček), Saetograptus leintwardinensis (Hopkinson), Lobograptus progenitor Urbanek, Lobograptus scanicus (Tullberg), Cucullograptus cf. aversus (Eisenack), Bohemograptus bohemicus bohemicus (Barrande), and Bohemograptus bohemicus tenuis (Bouček).
Sharbot Lake terrane and its relationships to Frontenac terrane, Central Metasedimentary Belt, Grenville Province: new insights from U–Pb geochronology
Authors: Corfu Fernando , Easton R. Michael
Published: October 2008

The Sharbot Lake terrane of the Central Metasedimentary Belt in Ontario comprises marbles, minor tholeiitic basalts and siliciclastic rocks, metamorphosed at low to moderate degrees, and is intruded by several suites of mafic to felsic plutons. Gabbroic and associated monzogranitic phases of the Lavant complex in northwestern parts of the terrane yield ages of 1224 ± 2 Ma for zircon and monazite, and 1221–1211 Ma for titanite. The Wolf Grove structure, a gneissic domain in the northeastern part of the area, was migmatized and intruded by granites at 1168 Ma prior to its tectonic juxtaposition on amphibolites and marbles of the Sharbot Lake terrane. Correlative events recorded by gneiss, quartzite, and marble from Carleton Place farther east stress the strong affinity of the Wolf Grove structure with rocks of the Frontenac terrane. The 1156 ± 2 Ma posttectonic Maberly stock intrudes rocks near the boundary zone between the Frontenac and Sharbot Lake terranes, suggesting that the two terranes were linked by 1156 Ma. The distribution of U–Pb ages for titanite, monazite, and rutile throughout the area emphasizes the distinctive metamorphic evolution characterizing different domains of the region, documents the lack of 1168 Ma metamorphic overprint in western domains, records the main 1168 Ma high-grade event and slightly younger subsidiary events in eastern domains, and indicates local resetting events. The combined data underline the geological complexity of the eastern Central Metasedimentary Belt, confirming the existence of significant compressional and metamorphic events in the period 1170–1160 Ma.
Isotopic and trace element constraints on the genesis of a boninitic sequence in the Thetford Mines ophiolitic complex, Quebec, Canada
Authors: Olive Valérie , Hébert Réjean , Loubet Michel
Published: October 2008

The Mont Ham Massif (part of the Thetford Mines ophiolite, south Quebec) represents a magmatic sequence made up of tholeiitic and boninitic derived products. A geochemical study confirms the multicomponent mixing models that have been classically advanced for the source of boninites, with slab-derived components added to the main refractory harzburgitic peridotite. An isochron diagram of the boninitic rocks is interpreted as a mixing trend between two components: (i) a light rare earth element (LREE) enriched component (A), interpreted as slab-derived fluid–melts equilibrated with sedimentary materials (εNd = −3,147Sm/144Nd = 0.140), and (ii) a LREE-depleted component (B) (0.21 < 147Sm/144Nd < 0.23), interpreted as slab-derived fluid–melt equilibrated with recycled Iapetus oceanic crust and equated to the Nd-isotope characteristics of the Iapetus mantle (εNd = 9). A multicomponent source is also necessary to explain the Nd-isotope and trace element composition of the tholeiites, which are explained by the melting of a more fertile, lherzolitic mantle and (or) mid-ocean ridge basalt source (component C), characterized by a large-ion lithophile element depleted pattern and an Iapetus mantle Nd isotopic composition (εNd = 9), mixed in adequate proportions with the two previously infered slab-derived components (A and B). The genesis of the boninites of Mont Ham is not significantly different from those of boninites located in the Pacific. An intraoceanic subduction zone appears to be an appropriate geodynamic environment for the Mont Ham ophiolitic sequence.
Grenvillian provenance for the amphibolite-grade Trap Falls Formation: implications for early Paleozoic tectonic history of New England
Authors: McDaniel D. K. , Hanson G. N. , McLennan S. M. , Sevigny J. H.
Published: October 2008

The Trap Falls Formation is a sequence of interlayered quartzites and schists that crops out in the Appalachian belt in southern Connecticut, and was deformed and metamorphosed to middle amphibolite grade during Acadian orogenesis. Schists have high Al2O3 and low CaO, Na2O, and K2O (chemical index of alteration CIA = 68–70), consistent with a significant weathering history in the sediment source. Rare earth element (REE) patterns for both schists and quartzites parallel post-Archean average Australian Shale, with light REE enrichment and well-developed Eu anomalies, suggesting an average upper crustal source. Whole-rock Nd and Pb isotopic analyses indicate old sources, with depleted mantle model ages (TDM) from 1880 to 1660 Ma, 207Pb/204Pb from 15.62 to 15.87, and 206Pb/204Pb from 19.11 to 22.08. U–Pb ages for single-grain and multigrain populations of detrital zircons range between 1113 and 992 Ma, the youngest of which defines a maximum depositional age for the Trap Falls Formation. U–Pb zircon ages indicate a late Grenvillian source for the zircons. Nd and Pb isotopic compositions are consistent with a source that is dominated by Grenville-age rocks with some component of older crust. Combining all of the data, we interpret that the protolith of the Trap Falls Formation was comprised of aluminous muds interbedded with clean quartz arenites, and suggest that they were deposited on the stable, trailing-edge margin of North America sometime during the Late Proterozoic to the Early Cambrian. The sediments were derived from a weathered source with an upper continental crust composition. Isotopic data and zircon ages indicate that this source was dominated by Grenville-age rocks.
Late Pleistocene chronology and paleoclimate of Vancouver Island determined from cave deposits
Authors: Gascoyne M. , Ford D. C. , Schwarcz H. P.
Published: October 2008

Speleothems from four caves in south-central Vancouver Island have been analysed by the 230Th/234U method. Only speleothems from one cave, Cascade Cave, near Port Alberni, contained sufficient uranium for them to be dated. Twenty-seven ages determined for seven speleothems were found to cluster in two periods: 67–28 ka, corresponding to the Olympia interstadial, and <23–10 ka (or <15 ka if corrected for detrital thorium contamination), corresponding to the Fraser (late Wisconsin) deglaciation and Holocene periods. Two speleothems were found to be deposited in isotopic equilibrium with their seepage waters. Profiles of variations in δ18O of the calcite (δ18Oc) of each of the two deposits show a decrease of 1.3‰ over the growth period, 64–28 ka. At all times, δ18Oc was less than δ18O of modern calcite in the cave. Using modern cave temperature and the variation of δ18O of seawater over the dated period, the profiles of δ18Oc are interpreted in terms of a paleotemperature record for the Olympia interstadial in Vancouver Island. The results show a gradual cooling from 4 °C at 64 ka, to 0 °C between 35 and 28 ka. These results are consistent with conditions necessary for speleothem growth and with published work on surficial Wisconsin deposits in the area. No distinct, short-period warming or cooling events are seen in the record, probably due to thermal buffering by the adjacent ocean.
The Spieden Group: an anomalous piece of the Cordilleran paleogeographic puzzle
Authors: Johnson Samuel Y.
Published: October 2008

Spieden and Sentinel Islands, San Juan Islands, Washington, are underlain by the only known occurrence of the Spieden Group, composed of the Upper Jurassic (Oxfordian or Kimmeridgian) Spieden Bluff Formation and the Lower Cretaceous (Valanginian and Hauterivian and possibly younger) Sentinel Island Formation, separated by a disconformity.The 100 m thick Spieden Bluff Formation is subdivided into two members: (1) an 80 m thick lower member, consisting of 5 m of sandstone, siltstone, and tuff overlain by 75 m of volcanic breccia–conglomerate largely of debris flow (laharic?) origin; and (2) a 20 m thick upper member consisting of fossiliferous sandstone and siltstone deposited on a shallow marine slope. Sedimentologic, petrologic, and geochronologic data suggest that sediments of the Spieden Bluff Formation accumulated near an active volcanic source to the north contributing primarily andesite, dacite, and basaltic andesite.The 740 m thick Sentinel Island Formation is also subdivided into two members: (1) a 140 m thick lower member consisting of fossiliferous sandstone and siltstone deposited in a shallow marine environment; and (2) an unconformably overlying 600 m thick upper member consisting of volcanic conglomerate deposited as an alluvial fan. The source terrane for the Sentinel Island Formation was also primarily Upper Jurassic volcanic rocks and lay to the northeast.Rocks of equivalent age occur in the southern part of the San Juan Islands and in neighboring geologic provinces, but most of these correlative rocks differ from the Spieden in sedimentology, structural style, and metamorphism. Juxtaposition of the Spieden Group and these correlative rocks might have been accomplished by shortening and fragmentation of a regional convergent margin, by large-scale transport of allochthonous blocks, or by some combination of the two mechanisms.
Chloroform–Methanol Extraction of Chlorophylla
Authors: Wood Lindsay W.
Published: October 2008

Chloroform–methanol (2:1, v/v) extracts significantly more (P < 0.001) chlorophyll a from algal cultures and from freshwater and seawater microcosms than does dimethyl sulfoxide, methanol, absolute methanol with hydrogen sulfide, or 90% acetone. For chlorophyte cultures it yields 97% or more of the chlorophyll a within a 4-h steeping period without grinding. It can be used with both calibrated spectrophotometry and fluorometric instrumentation. Sample filtration onto MgCO3-coated filters is recommended to ensure buffering of the extraction mixture. Holding the filters in chloroform–methanol at 4 °C or room temperature in the dark prevents loss of chlorophyll a for at least 10 d. More refined analyses of phaeophytin and other chlorophylls require the use of chloroform–methanol–water (2:2:1.8, by volume) and placement in a separatory funnel. After 24 h the lower (chloroform) layer contains all of the chlorophyll. Strict pH control is required for pheophytin determinations.
Assessing Significance of Physiological Differences among Three Esocids with a Bioenergefics Model
Authors: Bevelhimer Mark S. , Stein Roy A. , Carline Robert F.
Published: October 2008

To predict stocking success of esocids in Ohio waters with different thermal regimes, we measured individual food consumption, conversion efficiency, growth, and metabolic rate for Ohio stocks of northern pike (Esox lucius), muskellunge (E. masquinongy), and their hybrid, tiger muskellunge, in laboratory experiments. The first three parameters were quantified during 2-wk experiments of ad libitum feeding on fathead minnows (Pimephales promelas) at seven constant temperatures (5, 15, 20, 22.5, 25, 27.5, and 30 °C). The food consumption and growth data suggest that northern pike should grow faster than muskellunge at cool temperatures [Formula: see text], but slower than muskellunge at warm temperatures (>25 °C). Latitudinal differences in their natural distributions might explain this observation. Growth data of the hybrid showed no such obvious relationship to either of the parents. Metabolic rates were determined by measuring oxygen consumption in a closed, static respirometer at five constant temperatures (5, 15, 20, 25, and 30 °C). We found little difference in metabolic rates among the three taxa. To examine these data further, we used a bioenergetics model that simulated different stocking conditions, both natural (thermal regime and prey availability) and human controlled (stocking size and date). With this model, we predicted growth for 12–15 mo after stocking. In general, summer-stocked fish were about 35–90% larger 15 mo after stocking than were fall-stocked fish 12 mo after stocking. More specifically, the combined effect of ration and temperature permitted hybrids to grow faster than the parents in all simulations. Northern pike grew larger than muskellunge in a cool system, but smaller than muskellunge in a warm system with summer stocking. Based on bioenergetic considerations, tiger muskellunge should outgrow both northern pike and muskellunge in thermal regimes common to Ohio waters.
Dissipation of Permethrin in Limnocorrals
Authors: Solomon K. R. , Yoo J. Y. , Lean D. , Kaushik N. K. , Day K. E. , Stephenson G. L.
Published: October 2008

Permethrin (3-phenoxybenzyl(1RS)-cis,trans-3-(2,2-dimethy[-3-dichlorovinyl)-2,2-dimethylcyciopropanecarboxylate) applied to approximately 100-m3enclosures (limnocorrals) in a small mesotrophic lake in Southern Ontario (47°51′25″N; 77°25′30″W) at concentrations of 500, 50, 5, and 0.5 μ∙L−1dissipated from the water rapidly and approximated first-order kinetics in the first 8–12 d. Time taken for 50 and 90% dissipation ranged from 1.65 and 3.65 d, respectively, at 0.5 μ∙L−1to 3.5 and 6.75 d, respectively, at 50 μ∙L−1. Inter- and intra-seasonal replication of dissipation patterns was good. Rate of dissipation varied slightly with depth, normally being slower at greater depth. Absorption of permethrin to sediments was rapid, penetration shallow, and disappearance slow. Permethrin had no effect on water chemistry but there was an increase in the Secchi disk depth in the treated limnocorrals. Dissolved inorganic carbon decreased in all limnocorrals, including controls after treatment, suggesting precipitation of calcium carbonate which may act as a scavenging agent for permethrin in the water. Limnocorrals are a useful tool for evaluating the behavior of pesticides in the aquatic system.
Impact of Permethrin on Zooplankton Communities in Limnocorrals
Authors: Kaushik N. K. , Stephenson G. L. , Solomon K. R. , Day K. E.
Published: October 2008

A series of in situ aquatic enclosures or limnocorrals (5 × 5 × 5 m deep) was used to evaluate the impact of the insecticide permethrin (3-phenoxybenzy[(1RS)-cis,trans-3-(2,2-dimethyl-3-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate) (50.0 and 5.0 μg∙L−1 in 1979 and 5.0 and 0.5 μg∙L−1 in 1980) on the pelagic zooplankton community in a 10-ha mesotrophic lake in southern Ontario. Permethrin was acutely toxic to the macrozooplankton (Cladocera and Copepoda) at all concentrations; microzooplankton (Rotifera) showed acute toxicity only at 50.0 μg∙L−1. Despite this initial toxicity, the density of microzooplankton increased dramatically 15–20 d post-treatment in all treated enclosures, and the rotifer populations dominated the zooplankton community for 3–4 wk. The high densities of microzooplankton were attributed to their inherent reproductive capabilities when released from competition and predation pressures. Resilience of the different zooplankton taxa was variable and depended upon both the species and the exposure concentration. Diversity of zooplankton was significantly reduced in communities exposed to permethrin. The limnocorral technique has proved to be an important tool for assessment of direct and indirect impacts of pesticides on and probable recovery of a zooplankton community under natural conditions.
Zinc–Phosphorus Interactions and Variation in Zinc Accumulation during Growth ofChlamydomonas variabilis(Chlorophyceae) in Batch Culture
Authors: Bates Stephen S. , Tessier André , Campbell Peter G. C. , Létourneau Martin
Published: October 2008

Concentrations of EDTA-extractable zinc ([Zn]a~ surface-bound zinc) and non-EDTA-extractable zinc ([Zn]c~ transported zinc) were measured over the growth cycle of Chlamydomonas variabilis Dangeard growing in pH-controlled batch culture in the presence of six concentrations of free ionic zinc. Values of [Zn]agenerally decreased throughout the growth cycle in batch culture, the exact pattern of change depending on whether the cells used to inoculate the experiment were obtained from a stock culture in the exponential or stationary growth phase. Concentrations of cellular TCA-insoluble phosphorus (polyphosphate) also declined throughout the growth cycle. Values of [Zn]cincreased linearly throughout the exponential phase for growth at all zinc concentrations studied, but during the stationary phase they either reached a plateau for growth at 1.4 and 8.4 μmol Zn2+∙L−1, continued to increase linearly for growth at 13.2, 15.8, and 20.6 μmol Zn2+∙L−1, or declined for growth at 25.4 μmol Zn2+∙L−1. The cell yield of C. variabilis during the stationary phase was significantly decreased (by up to 90%) for growth in the presence of high concentrations of free ionic zinc. These cells also contained significantly more phosphorus than those grown in the presence of low free ionic zinc concentrations, but did not remove all of the initially added phosphorus from the growth medium. We hypothesize that cellular polyphosphate binds the transported zinc. As the concentration of cellular polyphosphate declines with increasing culture age, a portion of the previously bound intracellular zinc is released into the cell and exceeds a critical threshold, disrupting phosphorus metabolism, interfering with cell division, and decreasing cell yield.
Predicting the Effect of Macrobenthos on the Sediment/Water Flux of Metals and Phosphorus
Authors: Starkel William M.
Published: October 2008

The log-transformed flux rates of iron, manganese, and phosphorus in a small, softwater lake were linearly related to the biomass of Chaoborus and chironomid larvae. Flux rates were measured by measuring the change in chemical concentrations in the water overlying the sediment of undisturbed cores incubated in situ for 1–2 d. Predicted flux rates of iron and phosphorus at average pelagic densities of animals were enhanced at least twofold over predicted fluxes for diffusion alone. Macroinvertebrates had no apparent effect on flux rates of dissolved oxygen, dissolved inorganic carbon, potassium, or sodium.
Initial Changes in Use of Space and Food by Experimentally Segregated Populations of Dolly Varden (Salvelinus malma) and Cutthroat Trout (Salmo clarki)
Authors: Hume Jeremy M. B. , Northcote Thomas G.
Published: October 2008

Dolly Varden (Salvelinus malma) (N = 881) and cutthroat trout (Salmo clarki) (N = 1571) were captured from a native lacustrine sympatric stock and transferred to two nearby lakes, formerly fishless, to establish allopatric populations with genetic backgrounds similar to the donor stock. Nearshore (5- and 10-m depth contours) vertical distributions of segregated Dolly Varden and cutthroat trout, between spring and autumn of the first 18 mo after transfer, did not differ significantly from those in their sympatric lake. Dolly Varden were captured mainly near the bottom while cutthroat trout were more evenly distributed throughout the water column. Nevertheless, initially the allopatric Dolly Varden rapidly became highly planktivorous, virtually eliminating midwater populations of Chaoborus trivittatus and C. americanus (third and fourth instar larvae) within a year. They later ate mainly benthic organisms as in the sympatric lake. Although allopatric cutthroat trout had a similar effect on Chaoborus larvae in their lake, they also ate more large benthic prey than did those in sympatry with Dolly Varden in the donor lake. These results suggest that while there may be genetic control restricting broad vertical use of space by formerly sympatric Dolly Varden shortly after being placed in allopatry, such control is flexible enough that a highly benthofagous stock in sympatry quickly becomes planktivorous in the absence of cutthroat trout.
Responses of Lake Whitefish (Coregonus clupeaformis) to Fertilization of Lake 226, the Experimental Lakes Area
Authors: Mills K. H.
Published: October 2008

The responses of an unexploited population of lake whitefish (Coregonus clupeaformis) to fertilization of Lake 226 (L226), the Experimental Lakes Area, northwestern Ontario, were measured for 4 yr (1973–77). A vinyl sea curtain separated the lake into a northeast (NE) basin, which received P, N, and C additions, and a southwest (SW) basin, which received only N and C additions. Lake whitefish in the NE basin grew faster, had higher coefficients of condition, and had greater recruitment and production than those in the SW basin during the 2nd through 4th yr of fertilization. No differences between basins were detected in annual survival for fish [Formula: see text], but survival of age 0 fish was greater in the NE basin. Whitefish production in L226NE averaged twice that in L226SW from the 2nd to the 4th yr of fertilization, though significant variations occurred between years in both the NE and SW populations.
Bias in the Estimation of Functional Relationships from Time Series Data
Authors: Walters Carl J.
Published: October 2008

Functional relationships, such as stock–recruitment curves, are generally estimated from time series data where natural "random" factors have generated both deviations from the relationship and also informative variation in the independent variables. Even in the absence of measurement errors, such natural experiments can lead to severely biased parameter estimates. For stock–recruitment models, the bias is misleading for management: the stock will appear too productive when it is low, and too unproductive when it is large. The likely magnitude of such biases can and should be determined for any particular case by Monte Carlo simulations.
Ségrégation édaphique et bathymétrique chez le crabe des neiges, Chionoecetes opilio (O. Fabr.), dans le sud-ouest du golfe du Saint-Laurent
Authors: Coulombe Francis , Brêthes Jean-Claude F. , Bouchard Roxane , Desrosiers Gaston
Published: October 2008

A population of Chionoecetes opilio was studied during the summers of 1980 and 1981 in the southwestern Gulf of St. Lawrence, at the entrance of the Bay of Chaleur, and the Gaspé Bay. Sampling was conducted with beam trawls and baited traps at depths ranging from 45 to 125 m. Crab shell width of both sexes was measured and physiological maturity determined according to a biometrical index. Immature individuals of both sexes are essentially localized on the upper bathymetrical levels, on gravelly mud, whereas adults are found mainly on mud or sandy mud bottoms. We hypothesize that young crabs move down to the muddy bottom where recruitment to the fishery occurs. This deplacement seems to be concomitant with physiological maturity.
Effects of Dietary 17α-Methyltestosterone and Bovine Growth Hormone on Growth and Food Conversion of Slow- and Normally-Growing American Elvers (Anguilla rostrata)
Authors: Degani Gad , Gallagher Margie Lee
Published: October 2008

Dietary addition of 17α-methyltestosterone (MT) and bovine growth hormone (bGH) had a significant effect on growth and food conversion in American elvers (Anguilla rostrata). Both MT (1 μg/g) and bGH (2 and 10 μg/g) significantly increased the mean weight of elvers compared with controls. Higher concentrations of MT (10 μg/g) increased mean body weight, but not significantly. The effects of MT were more pronounced in normally-growing elvers compared with slow-growing elvers. Reduction of water temperature had a much stronger influence on weight gain in slow-growing elvers receiving MT than with normally-growing eels receiving MT. Food conversion was improved by feeding either MT or bGH. Food conversion was generally lower in slow-growing than in normally-growing elvers. Total body protein was related to body weight and was significantly lower in elvers fed MT than in control elvers. However, there was no significant difference in total body protein elvers fed bGH compared with the control group.
Size-Selective Feeding by the Predatory Copepod Epischura lacustris Forbes
Authors: Wong C K. , Sprules W. G.
Published: October 2008

Size-selective predation by Epischura lacustris on Bosmina longirostris was investigated in the field by comparing the size distributions of Bosmina available in the water column with the carapace sizes of killed Bosmina. While Epischura could consume the entire size range (0.2–0.4 mm) of Bosmina, smalt prey (0.2–0.25 mm) consistently constituted the greatest portion of the diet. For Bosmina, vulnerability depended on the rate of encounter with the predator and on the probability of ingestion by the predator. The frequencies of different-sized prey in the diet were partially predicted on the basis of their relative abundance weighted by their ingestion probabilities. The prediction could be improved if encounter rates were known.
The Uncertain Influence of Spring Photoperiod on Spawning in the American Lobster, Homarus americanus
Authors: Aiken D. E. , Waddy S. L.
Published: October 2008

The literature contains a report that induction of final vitellogenesis and time of spawning in American lobsters (Homarus americanus) is controlled by spring photoperiod. However, we could not corroborate this. Two experiments with American lobsters held throughout the winter in Canadian Atlantic seawater temperatures indicated no effect of spring photoperiod on time of spawning. In one experiment the onset of spring photophase was delayed by 2 mo. In the second experiment the photophase at the winter solstice (9 h 46 min) was gradually shortened over ensuing months to 5 h 30 min on 7 July. Neither of these treatments altered the time of spawning relative to control animals on a simulated natural photoperiod cycle. Spawning occurred at photoperiods of LD 6:18 and LD 15:9.
ATOMIC HYDROGEN-DRIVEN SIZE CONTROL OF CATALYTIC NANOPARTICLES FOR SINGLE-WALLED CARBON NANOTUBE GROWTH
Authors: JEONG HEE JIN , EUDE LAURENT , GOWTHAM MANOHARAN , MARQUARDT BERND , LIM SUNG HUN , ENOUZ SHAÏMA , COJOCARU COSTEL SORIN , PARK KYUNG AH , LEE YOUNG HEE , PRIBAT DIDIER
Published: October 2008

The effects of an atomic hydrogen ( H at ) pretreatment of the catalyst layer on the low temperature growth of single-walled carbon nanotubes (SWCNTs) have been investigated using a modified catalytic chemical vapor deposition system. Well-defined and isolated individual Fe nanoparticles as a catalyst are successfully formed on the defects with high trapping energy which are created on the Al 2 O 3 surface by H at pretreatment, yielding highly dense SWCNTs. The pretreatment mechanism of H at , compared to H 2 , is also discussed. It was also found that the quality of SWCNTs can be enhanced when H at is flowed with CH 4 during nanotubes growth at low temperature. In this case, the undesired carbon products and defects on catalyst seeds and nanotube walls can be selectively removed by H at . Therefore it is essential to use H at in the pretreatment stage for increasing catalytic activity and to keep the size of nanoparticles in the nm range. H at can also be employed in growth stage for enhancing SWCNTs quality and density at low temperature.
Recent Developments in the Thermally Activated Delayed Fluorescence of Fullerenes
Authors: Baleizão Carlos , Berberan-Santos Mario N.
Published: October 2008

Recent developments in fundamental aspects and applications of the thermally activated delayed fluorescence (TADF) displayed by fullerenes are presented. It is shown that from the analysis of steady-state data, time-resolved data, or a combination of both, it is possible to determine several important photophysical parameters. Outstanding temperature and oxygen sensors based on the TADF effect exhibited by fullerene C70 are also briefly discussed.
Aligned Carbon Nanotube Structures
Authors: Mirza Shamim , Grebel Haim
Published: October 2008

One of the foreseen applications for carbon nanotubes is the ability to fabricate anisotropic carbon nanotube (CNT) films. This work is dwelling on the characteristics of aligned and functionalized CNT based films and junctions between them.
Electrochemical Capacitance from Carbon Nanotubes Decorated with Cobalt Oxide Nanoparticles in Alkali Electrolyte
Authors: Heish Chien-Te , Lin Jia-Yi
Published: October 2008

Deposition of cobalt oxide nanoparticles on CNTs was performed to examine the influence of Co3O4 loading on the electrochemical capacitance of CNT electrodes. X-ray diffraction revealed that the Co3O4 belongs to spinel crystalline structure. Cyclic voltammetric study on the resulting electrodes showed that both of contributor of pseudocapacitance and double-layer capacitance increase significantly after the deposition of Co3O4. Constant current charge-discharge cycling also reflected the capacitance enhancement contributed from Co3O4 deposition, i.e., an increase of capacitance from 83.5 F/g to 185.5 F/g at a current density of 0.5 mA/cm2. This result reflected that attached Co3O4 can be served as an electroactive site in facilitating an additional specific capacitance. Equivalent circuit analysis on impedance spectra indicated that both of electrical connection and charge transfer resistances accounted for the major proportion of the overall resistance and were found to slightly decrease after the attachment of Co3O4.
Cage-Like Based Materials with Carbon and Silicon
Authors: Melinon Patrice , Masenelli Bruno
Published: October 2008

Carbon fullerenes belong to the huge family of cage-like molecules. Although, no silicon fullerene synthesis has been reported yet, large surface reconstruction in small silicon clusters presents some striking similarities with fullerenes. The difference is due to the presence of silicon atoms inside the cage ("stuffed" fullerene). Of course, the existence of cage-like clusters can be questioned in mixed SiC structures, the main parameter being the stoichiometry. On the other hand, complex silicon fullerene architecture can be synthesized when the cages share a common face. Such a three dimension structure named "clathrate" belongs to the huge family of the zeolites. All these open structures allow the incorporation of guest atoms. The coupling between the guest atoms and the host lattice and the concentration of the encapsulated atoms are adjusting parameters. Numerous applications including electrical and thermal transport, hard materials devices, storage and optics devices will be evoked.
Effects of Dendrimer-Functionalized Multi-Walled Carbon Nanotubes on Murine Embryonic Stem Cells
Authors: Cui Daxiang , Zhang Hong , Wang Zheng , Asahi Toru , Osaka Tetsuya
Published: October 2008

Herein we firstly reported the effects of generation 5 polyamidoamine dendrimer-functionalized fluorescent multi-walled carbon nanotubes(dMNTs) on mice embryonic stem cell line CCE. The dMNTs were prepared and characterized, and incubated with mice ES CCE cells for 1 to 5day. These ES cells were observed by fluorescent microscopy, and were analyzed by flow cytometer and MTT. Results showed that the dendrimer-functionalized fluorescent multi-walled carbon nanotubes were successfully synthesized, could enter into ES cells quickly, more than 20μmicrogram/ml dose caused ES cells become smaller and smaller as the incubation time increased, and inhibited cell growth in dose- and time-dependent means, less than 5 μmicrogram/ml dose improves ES differentiation. These results demonstrate that dMNTs are toxic to ES cells at large dose, can induce ES cells' differentiation at small dose. The prepared dMNTs may be a highly efficient gene delivery system for ES cells, have potential applications in ES research.
Electrodeposition of Platinum on Carbon Black for Fuel Cell Application
Authors: Martín Antonio J. , Chaparro Antonio M. , Folgado M. Antonia , Gallardo Blanca , Daza Loreto
Published: October 2008

The electrodeposition of Pt is carried out on carbon black, from a solution of hexachloroplatinic acid, using cyclic voltammetry and pulse deposition. The substrate is previously submitted to an activation process, consisting in the formation of a hydrophilic overlayer. SEM and TEM images show that surface C black particles are totally or partially covered, depending on electrodeposition conditions. Cross section analysis shows that the deposit occurs to a depth of less than 5 µm. Results from single cell testing are shown.
Failure Analysis of Electroplated Metallic Components
Authors: Suess Steven J. , Brown Craig C.
Published: October 2008

Electroplating is used to apply metallic deposits to a wide range of components for both functional and decorative purposes. Careful control of the pre-treating and application processes is required in order to produce repeatable, high-quality surface finishes. Most of the problems that are encountered during electroplating are ideally discovered and corrected prior to shipment of the products, although some issues do not become clearly evident until after the parts are put into service. In either case, it is important to recognize the results of common electroplating pitfalls so that proper corrective measures can be taken. This article reviews common problems that are experienced in electroplating metallic components.
Structural, Optical and Electrical Properties of CdxZn1-xSe Films
Authors: Murali K. R. , Balasubramanian M.
Published: October 2008

Thin films of cadmium zinc selenide have been deposited at room temperature by the pulse plating technique using ZnSO4, CdSO4 and SeO2 at room temperature and a deposition potential of - 0.9V. The duty cycle was varied in the range of 6 - 50 %. X-ray diffraction studies indicate the formation of cubic structure. The band gap increases from 1.72eV for CdSe films to 2.70eV for ZnSe films as the concentration of ZnSe increases. AFM studies indicated that the average grain size increases from 30 nm to 125 nm with increasing concentration of Zn.The values of the resistivity decreases from 10000 ohm cm to 100 ohm cm for the films deposited at a duty cycle of 50 % as the concentration of CdSe increases.
Properties of CdSe Films Pulse Plated on High Temperature Substrates
Authors: Murali K. R. , Thilakavathy K. , Vasantha S , Oommen Rachel
Published: October 2008

CdSe films(1cm2 area) were deposited on titanium and conducting glass substrates at 50 % duty cycle and at different deposition temperatures in the range of 30 - 80{degree sign}C. The deposition current density was maintained constant at 100 mA cm-2. . The prominent peaks corresponding to (the hexagonal phase are observed in all cases. The crystallite size increased with deposition temperature. The cross plane resistivity was found to increase from 20 to 60 Ω cm with increase of substrate temperature. Photoelectrodes with high efficiency were obtained.
Properties of ZnSe Films Pulse Plated on High Temperature Substrates
Authors: Murali K. R. , Vasantha S , Thilakavathy K. , Oommen Rachel
Published: October 2008

ZnSe films were deposited on titanium and conducting glass substrates at 50 % duty cycle and at different deposition temperatures in the range of 30 - 80{degree sign}C. The deposition current density was maintained constant at 100 mA cm-2. . The prominent peaks corresponding to the cubic phase are observed in all cases. The crystallite size increased with deposition temperature. The cross plane resistivity was found to decrease with increase of substrate temperature.
Characteristics of Pulse Deposited CdxZn1-xTe Films
Authors: Murali K. R. , Rajkumar P. R.
Published: October 2008

CdxZn1-xTe films were pulse electrodeposited on titanium and conducting glass substrates from the precursors at 70{degree sign}C and at different duty cycles in the range 6 - 50 %. A deposition potential of -0.90V(SCE) was employed. The films were polycrystalline with cubic structure. Bandgap of the films varied in the range of 1.48 - 2.29 eV as the ZnTe concentration increased. Raman studies indicated LO and TO modes. The crystallite size increased from 30 - 80 nm as the ZnTe concentration increased. Solar cells based on cadmium zinc telluride films fabricated using the films of different composition deposited by pulse plating on conducting tin oxide substrates exhibited a Voc of 0.35V and Jsc of 10.5 mA cm-2.
Electroless Deposition of Metals on Nanopatterns of Organosilane SAMs
Authors: Li Jie-Ren , Garno Jayne C.
Published: October 2008

Hybrid metal-organic architectures can be fabricated at the nanoscale using guided self-assembly on well-defined organic scaffolds to produce layered nanostructures. We have developed a new chemical approach to fabricate nanopatterns of metal nanostructures via electroless metal deposition of nanopatterned silane thin films. First, a surface with different functionalities is prepared with engineered nanopatterns of adhesive and resistive silanes. Next, the organosilane nanopatterns are used as a foundation for site-selective electroless deposition of metals such as iron oxide.
Iodine Patterns on Chemical Templates
Authors: Cai Yuguang
Published: October 2008

Iodine patterns were fabricated on hydrophilic nanometer scale chemical templates through the "Wetting Driven Assembly". The iodine patterns followed the shape and size of the underneath chemical templates. By varying the evaporation rate and the iodine concentration, we studied the evaporation dynamics of the iodine solution on the chemical templates. We found that the slow evaporation favored the "coffee ring" effect. Most of the iodine was deposited on the edge of the chemical template under the slow solvent evaporation. In contrast, fast evaporation favored the "Mexican Hat" effect - The iodine formed a "Mexican Hat" shaped pattern on a disc shaped chemical template. Furthermore, we found the iodine chloroform solution drop still behaved as a liquid at ~20 nm scale.
Bismuth Telluride Nano-Coolers for Magnetic Sensors
Authors: Mannam Raja , Kola Avinash , Agarwal Mangilal , Singh Varshini , Roy Amitava , Young David , Varahramyan Kody , Davis Despina
Published: October 2008

A novel conceptual mechanism for cooling Giant magneto resistance (GMR) nanostructures using bismuth telluride (BixTey) thermoelectric caps is reported for first time. BixTey thin films and nanowires were electrodeposited from an aqueous electrolyte solution using a constant potential method. GMR layered structures were electrodeposited form a Co-rich electrolyte using a pulsed potential technique. Optimal deposition potentials were identified from polarization analysis. Thin film morphology was found to be strongly dependent on deposition potentials. With increased deposition potentials crystalline to polycrystalline transition and decreased Te concentration were observed from XRD and EDS analysis, respectively. A maximum Seebeck coefficient of -200μV/K was obtained at 345K for a thin film sample deposited at -150mV.
Knockdown of hepatocyte aquaporin-8 by RNA interference induces defective bile canalicular water transport
Authors: Larocca M. Cecilia , Soria Leandro R. , Espelt M. Victoria , Lehmann Guillermo L. , Marinelli Raúl A.
Published: October 2008

Aquaporin-8 (AQP8) water channels, which are expressed in rat hepatocyte bile canalicular membranes, are involved in water transport during bile formation. Nevertheless, there is no conclusive evidence that AQP8 mediates water secretion into the bile canaliculus. In this study, we directly evaluated whether AQP8 gene silencing by RNA interference inhibits canalicular water secretion in the human hepatocyte-derived cell line, HepG2. By RT-PCR and immunoblotting we found that HepG2 cells express AQP8 and by confocal immunofluorescence microscopy that it is localized intracellularly and on the canalicular membrane, as described in rat hepatocytes. We also verified the expression of AQP8 in normal human liver. Forty-eight hours after transfection of HepG2 cells with RNA duplexes targeting two different regions of human AQP8 molecule, the levels of AQP8 protein specifically decreased by 60–70%. We found that AQP8 knockdown cells showed a significant decline in the canalicular volume of ∼70% ( P < 0.01), suggesting an impairment in the basal (nonstimulated) canalicular water movement. We also found that the decreased AQP8 expression inhibited the canalicular water transport in response either to an inward osmotic gradient (−65%, P < 0.05) or to the bile secretory agonist dibutyryl cAMP (−80%, P < 0.05). Our data suggest that AQP8 plays a major role in water transport across canalicular membrane of HepG2 cells and support the notion that defective expression of AQP8 causes bile secretory dysfunction in human hepatocytes.
Direct association of calponin with specific domains of PKC-α
Authors: Somara Sita , Bitar Khalil N.
Published: October 2008

Calponin contributes to the regulation of smooth muscle contraction through its interaction with F-actin and inhibition of the actin-activated Mg-ATPase activity of phosphorylated myosin. Previous studies have shown that the contractile agonist acetylcholine induced a direct association of translocated calponin and PKC-α in the membrane. In the present study, we have determined the domain of PKC-α involved in direct association with calponin. In vitro binding assay was carried out by incubating glutathione S-transferase-calponin aa 92-229 with His-tagged proteins of individual domains and different combinations of domains of PKC-α. Calponin was found to bind directly to the full-length PKC-α. Calponin bound to C2 and C4 domains but not to C1 and C3 domains of PKC-α. When incubated with proteins of different combination of domains, calponin bound to C2-C3, C3-C4, and C2-C3-C4 but not to C1-C2 or C1-C2-C3. To determine whether these in vitro bindings mimic the in vivo associations, and in vivo binding assay was performed by transfecting colonic smooth muscle cells with His-tagged proteins of individual domains and different combinations of domains of PKC-α. Coimmunoprecipitation of calponin with His-tagged truncated forms of PKC-α showed that C1-C2, C1-C2-C3, C2-C3, and C3-C4 did not associate with calponin. Calponin associated only with full-length PKC-α and with C2-C3-C4 in cells in the resting state, and this association increased upon stimulation with acetylcholine. These data suggest that calponin bound to fragments that may mimic the active form of PKC-α and that the functional association of PKC-α with calponin requires both C2 and C4 domains during contraction of colonic smooth muscle cells.
Distribution and function of monoacylglycerol lipase in the gastrointestinal tract
Authors: Duncan Marnie , Thomas Adam D. , Cluny Nina L. , Patel Annie , Patel Kamala D. , Lutz Beat , Piomelli Daniele , Alexander Stephen P. H. , Sharkey Keith A.
Published: October 2008

The endogenous cannabinoid system plays an important role in the regulation of gastrointestinal function in health and disease. Endocannabinoid levels are regulated by catabolic enzymes. Here, we describe the presence and localization of monoacylglycerol lipase (MGL), the major enzyme responsible for the degradation of 2-arachidonoylglycerol. We used molecular, biochemical, immunohistochemical, and functional assays to characterize the distribution and activity of MGL. MGL mRNA was present in rat ileum throughout the wall of the gut. MGL protein was distributed in the muscle and mucosal layers of the ileum and in the duodenum, proximal colon, and distal colon. We observed MGL expression in nerve cell bodies and nerve fibers of the enteric nervous system. There was extensive colocalization of MGL with PGP 9.5 and calretinin-immunoreactive neurons, but not with nitric oxide synthase. MGL was also present in the epithelium and was highly expressed in the small intestine. Enzyme activity levels were highest in the duodenum and decreased along the gut with lowest levels in the distal colon. We observed both soluble and membrane-associated enzyme activities. The MGL inhibitor URB602 significantly inhibited whole gut transit in mice, an action that was abolished in cannabinoid 1 receptor-deficient mice. In conclusion, MGL is localized in the enteric nervous system where endocannabinoids regulate intestinal motility. MGL is highly expressed in the epithelium, where this enzyme may have digestive or other functions yet to be determined.