bluuebunny/crossref_metadata_2025 huggingface dataset:
Taxonomic implications of gamete fusions in the parasitic brown alga Herpodiscus durvillaeae
Authors: Peters Akira F.
Published: October 2008

Field material of Herpodiscus durvillaeae, a New Zealand endemic parasitic brown alga growing in the thalli of Durvillaea antarctica, was studied in the laboratory. Pale zoids released from diminutive gametophytes, which were attached to the walls of unilocular sporangia and vegetative filaments of Herpodiscus, acted as isogametes. A heteromorphic life cycle with alternation of an endophytic parasitic sporophyte and a diminutive gametophyte is thus proposed for H. durvillaeae, and taxonomic implications of this life history are discussed. Key words: Herpodiscus durvillaeae, sexuality, life history, Phaeophyceae, Durvillaea antarctica, parasite.
New accelerator mass spectrometry radiocarbon ages for the Mazama tephra layer from Kootenay National Park, British Columbia, Canada
Authors: Hallett D. J. , Hills L. V. , Clague J. J.
Published: October 2008

Charcoal fragments recovered from the Mazama air-fall tephra layer in cores from Dog and Cobb lakes, Kootenay National Park, British Columbia, yielded accelerator mass spectrometry ages of 6720 ± 70 and 6760 ± 70 14C years BP, respectively. These two new ages, together with other previously published radiocarbon ages on charcoal and twig fragments from Mazama air-fall deposits, indicate that the climactic eruption of Mount Mazama occurred 6730 ± 40 14C years BP.
The type specimens (Middle Cambrian) of the trace fossil Archaeonossa Fenton and Fenton
Authors: Yochelson Ellis L. , Fedonkin Mikhail A.
Published: October 2008

The original description of Archaeonossa, from beds considered Early Cambrian but now dated as early Middle Cambrian, included at least two unrelated forms of trace fossils. The ichnogenus and the type ichnospecies are redefined, a lectotype is designated, and the type material is reiilustrated, along with topotype material from Yoho National Park, British Columbia. Although this trace fossil was originally attributed to movement by a gastropod, it is concluded, on the basis of restudy, that the type occurrence should not be used as evidence of activity by Gastropoda.
Crustal assimilation in the Burnt Lake metavolcanics, Grenville Province, southeastern Ontario, and its tectonic significance
Authors: Smith T. E. , Holm P. E. , Dennison N. M. , Harris M. J.
Published: October 2008

Three intimately interbedded suites of volcanic rocks are identified geochemically in the Burnt Lake area of the Belmont Domain in the Central Metasedimentary Belt, and their petrogenesis is evaluated. The Burnt Lake back-arc tholeiitic suite comprises basalts similar in trace element signature to tholeiitic basalts emplaced in back-arc basins formed in continental crust. The Burnt Lake continental tholeiitic suite comprises basalts and andésites similar in trace element composition to continental tholeiitic sequences. The Burnt Lake felsic pyroclastic suite comprises rhyolitic pyroclastics having major and trace element compositions that suggest that they were derived from crustal melts. Rare earth element models suggest that the Burnt Lake back-arc tholeiitic rocks were formed by fractional crystallization of mafic magmas derived by approximately 5% partial melting of an amphibole-bearing depleted mantle, enriched in light rare earth elements by a subduction component. The modelling also suggests that the Burnt Lake continental tholeiitic rocks were formed by contamination – fractional crystallization of mixtures of mafic magmas, derived by ~3% partial melting of the subduction-modified source, and rhyolitic crustal melts. These models are consistent with the suggestion that the Belmont Domain of the Central Metasedimentary Belt formed as a back-arc basin by attenuation of preexisting continental crust above a westerly dipping subduction zone.
Paleoecology of selected conodontophorid species from the Cobbs Arm Formation (middle Ordovician), New World Island, north-central Newfoundland
Authors: Fåhræus Lars E. , Hunter David R.
Published: October 2008

The upper Chazyan (Llandeilian) Cobbs Arm Formation of New World Island, north-central Newfoundland, consists of pure limestones and limestones with varying amounts of volcaniclastic admixture interbedded with calcareous tuff. The depositional environment for the Cobbs Arm Formation was that of a volcanic island arc waning in volcanic activity. A rich and varied conodontophorid fauna has been identified from the limestones. Conodontophorid diversity is low in the limestones with high volcaniclastic admixtures; these were probably deposited in a nearshore, but not necessarily very shallow, environment. Farther offshore where there was less or no admixture of volcanic material the diversity is found to be the highest. Samples from environments of very high wave or current energy show very low diversity or are entirely lacking in conodonts. Distributions of individual conodontophorid species show repetitive patterns with regard to co-occurrences, reciprocal relationships, mutually exclusive occurrences, and correlations with sediment types. The paleoecology of the following species is discussed: Baltoniodus prevariabilis–B. variabilis transition, B. variabilis, Eoplacognathus lindstroemi, E. robustus, Panderodus gracilis, Periodon aculeatus, Protopanderodus varicostatus, Pygodus anserinus, P. serrus, Strachanognathus parva, Walliserodus ethingtoni, and W. nakholmensis. The biostratigraphic implications with particular regard to P. serrus and P. anserinus are discussed and it is concluded that the P. serrus–P. anserinus transition (speciation event) probably has less chronostratigraphic value than previously assumed.
Fabric and origin of gneissic layers in anorthositic rocks of the St. Charles sill, Ontario
Authors: Rousell D. H.
Published: October 2008

The St. Charles sill is located in the Grenville Province and consists of rocks of the anorthosite suite. The sill is a northwesterly trending body, 11 km long and as much as 0.8 km wide, and with a steep dip to the northeast. The sill is characterized by interlayered massive and gneissic rocks metamorphosed under conditions of the amphibolite facies. In the massive rocks plagioclase occurs as strongly twinned laths that range in size from fine-grained crystals to megacrysts. Hornblende, biotite, and garnet occur as subophitic masses and apparently replace original pyroxene. In the gneissic rocks the plagioclase ranges in size from fine to coarse grained and the primary grains are partially replaced by elongate, weakly twinned, anhedral plagioclase. The gneissosity is defined by a dimensional preferred orientation of biotite, hornblende, and secondary plagioclase. The formation of the secondary plagioclase is attributed largely to growth by grain boundary diffusion and, to a lesser extent, by replacement of primary plagioclase by grain boundary migration. In the diffusion mechanism strain rate is inversely proportional to grain size and it is interpreted that the tectonic fabric developed in the finer grained layers of the sill while the coarser grained layers remained essentially undeformed.
Seismicity in the Mica Reservoir (McNaughton Lake) area: 1973–1978
Authors: Ellis R. M. , Chandra B.
Published: October 2008

Impoundment of McNaughton Lake was initiated on March 29, 1973 and full load of 25 × 109 m3 and maximum depth of 191 m were first achieved in August 1976. The reservoir lies principally in the Rocky Mountain Trench, a major structural boundary between the Rocky Mountain Thrust Belt to the east and the Eastern Metamorphic Belt to the west. Although the regional seismicity is moderate, with an average of about one earthquake with Richter magnitude ML ≥ 3.0 every 2 years in the period 1963–1972, a magnitude 6 earthquake occurred adjacent to the present reservoir site in 1918.A monitoring program initiated in January 1973 has located 212 earthquakes with M ≥ 1.5; the largest ML = 4.8. Most of the seismicity was confined to four sequences. The first swarm started prior to initiation of impoundment. The next two sequences occurred in the same area 17 km into the Rocky Mountains from the central section of the reservoir. The final sequence, consisting of the ML = 4.8 earthquake and its aftershocks, had a preferred epicentre 4 km east of the Rocky Mountain Trench near the northern section of the reservoir. Comparison of the characteristics of the earthquake sequences with data from reservoirs where seismicity has been induced indicates that the observed seismicity at McNaughton Lake is unlikely to have been induced.The regional seismicity pattern from 1973 to 1978 was similar to that of the historical record: distributed earthquakes in the Rocky Mountains and in the adjacent Monashee and Cariboo Mountains of the Eastern Metamorphic Belt, no earthquakes within the Rocky Mountain Trench, and the Selkirk Mountains continuing to be almost aseismic. Both the regional seismicity and swarms yield b values near 0.65. Inclusion of the historical data with the regional seismicity gives b = 0.74 ± 0.08.
Tectonic history of the Queen Charlotte Islands and adjacent areas—a model
Authors: Yorath C. J. , Chase R. L.
Published: October 2008

The region including Queen Charlotte Islands, Hecate Strait, and Queen Charlotte Sound is underlain by two allochthonous terranes, Wrangellia and the Alexander terrane. The suture between them occurs in central Graham Island and central Hecate Strait and is coincident with the traces of the Sandspit and Rennell Sound fault zones, each of which developed in response to crustal rifting in Queen Charlotte Sound during mid-Tertiary time.The stratigraphic succession comprises four tectonic assemblages. (1) The allochthonous assemblages comprise Paleozoic rocks of the Alexander terrane and Upper Triassic and Jurassic rocks of Wrangellia, which on the basis of paleomagnetic and biogeographical data are clearly exotic. The distribution of these terranes beneath Queen Charlotte Sound and Hecate Strait is supported by geophysical information and subsurface data obtained from offshore wells. (2) The suture assemblage is represented by extremely coarse conglomerates, massive graywackes, and turbidites of Early Cretaceous age, and possibly by Upper Jurassic plutons. (3) The post-suture assemblage is expressed by the tripartite succession of the mid- to Upper Cretaceous Queen Charlotte Group whose middle component, the Honna Formation, comprises polymictic conglomerates that may have resulted from the final accretion of the amalgamated crustal fragments of the Alexander Terrane and Wrangellia to the continental margin. (4) The rift assemblage is expressed by mid- to upper Tertiary volcanics, epizonal plutons, and terrigenous clastics. Rifting is believed to have occurred in Queen Charlotte Sound above a mantle plume and resulted in crustal attenuation through development of listric, crustal-penetrative normal faults, and concurrent extrusion of subaerial volcanics and emplacement of high-level plutons. The attenuation caused northward motion of the Queen Charlotte Islands along the Louscoone Inlet – Sandspit fault zone and subsidence in Queen Charlotte Sound where Lower Miocene marine sediments were deposited within the rift zone. Later, additional rifting in southern Hecate Strait resulted in the reactivation of the old suture zone, manifest as the Rennell Sound fault zone. Concurrent with continued terrigenous deposition and volcanism, the Queen Charlotte Islands moved northwesterly along the Rennell Sound Fault, which disrupted the earlier fault trend. The final rotation of the islands to their modern position was accomplished through left-lateral motion along the Beresford Bay and Langara Faults.
Late Pleistocene fish fossils of Coregonus, Stenodus, Thymallus, Catostomus, Lota, and Cottus from the Old Crow basin, northern Yukon, Canada
Authors: Cumbaa Stephen L. , McAllister Don E. , Morlan Richard E.
Published: October 2008

Fossils of the broad whitefish, Coregonus nasus; the inconnu, Stenodus leucichthys; the longnose sucker, Catostomus catostomus; and the burbot, Lota lota, are reported for the first time from North America and a freshwater sculpin, Cottus, for the first time from Yukon Territory. The known fossil occurrence of the Arctic grayling, Thymallus arcticus, in North America is extended from 32 000 to about 60 000 years BP. These six fossils represent about one sixth of the present-day Yukon freshwater ichthyofauna of 35 species.These fossils provide a major test for the method of determining glacial refugia based on geographic variation of morphological or protein characters. They confirm that these taxa were present prior to and presumably survived the Wisconsinan glaciation in a Beringian refugium.The occurrence of these fossils, all subarctic or subarctic–boreal species known at present in the same area, does not suggest a paleoenvironment greatly different from the present one.
Fleet Dynamics and Individual Variation: Why Some People Catch More Fish than Others
Authors: Hilborn Ray
Published: October 2008

Most fisheries problems arise from a failure to understand and manage fishermen, and that the study of fishermen should be a major part of fisheries research. The dynamic behavior of fishing fleets can be broken into four components: investment, movement, catching power, and discarding. The literature in each area is reviewed and the needed research described. The second part of this paper examines the causes and consequences of individual variation in catch in a commercial purse seine fishery and a recreational hook and line fishery. It is shown that the catch is highly concentrated in the recreational fishery with a small proportion of frequent anglers catching a large portion of the fish. Catch is more equitably distributed in the purse seine fishery. The consequence of individual variation includes the observation that small annual bag limits in the sport fishery could reduce the total catch significantly while leaving most anglers unaffected and the fact that buy back of the most successful vessels would reduce the commercial catch by relatively little.
Conversion of Blade Length Increments into Biomass Production Estimates in Laminaria longicruris
Authors: Gendron L.
Published: October 2008

Three different methods to convert kelp blade length increments into biomass production estimates were compared for Laminaria longicruris. The first two models, the exponential and the chordal models, rely on a generalized blade length to weight relationship, whereas the third, the biomass model, is independent of such generalizations. Differences between the three models were examined for the entire range of blade sizes, for which linear growth was measured during three consecutive 3-wk periods, from June to August 1982. There were no significant differences between the two first models although estimates using the chordal model were constantly and slightly lower (<10%) than those using the exponential model. There were significant differences between the biomass model and the others; the differences increased directly with blade size. Biomass production estimates of larger blades obtained using the biomass model were up to 45% lower than with the exponential model. A correction equation related to blade size, based on estimates obtained using the biomass model, was calculated for the exponential model. The correction equation provides a means for comparing or converting year-round estimates obtained by either methods, for different size-structured populations of L. longicruris of sheltered habitats.
Natural Hybridization between Steelhead Trout (Salmo gairdneri) and Coastal Cutthroat Trout (Salmo clarki clarki) in Two Puget Sound Streams
Authors: Campton Donald E. , Utter Fred M.
Published: October 2008

A genetic investigation of anadromous trout populations in the Puget Sound area revealed numerous juvenile individuals from two streams with electrophoretic phenotypes consistent with those expected for hybrid descendents of steelhead trout (Salmo gairdneri) and coastal cutthroat trout (S. clarki clarki). The likelihood of hybridization was evaluated with a hybrid index measuring the relative probability that the combined genotype for a particular fish at several diagnostic loci could have arisen by random mating within each of the two Salmo species. The distribution of hybrid index scores among fish from the two creeks clearly demonstrated the genetic distinctness of the two species and the intermediate genotypic composition of the unknown fish. We concluded that these electrophoretically intermediate fish were natural steelhead–cutthroat hybrids based on their restricted occurrence at specific sample sites in only 2 of 23 streams surveyed, the linear distributions of juveniles from the two parental species within each stream, and the distribution of hybrid index values for a hatchery population of known mixed ancestry. Further, from estimates of gametic disequilibria and the absence of a consistent excess of heterozygotes we suggest that backcrossing may have occurred. The existence of these natural hybrids raises many questions concerning the biological bases for maintaining species integrities in regions of sympatry and indicates the need to fully understand the biological consequences of present and future management practices.
Feeding Ecology of the Sauger (Stizostedion canadense) in a Large River
Authors: Wahi David H. , Nielsen Larry A.
Published: October 2008

In stomachs of 550 sauger (Stizostedion canadense) collected by gillnetting in the Ohio River during June 1980 through August 1981, Dorosoma cepedianum were the most abundant prey (42% of all identified prey), followed by Notropis atherinoides (28%), Aplodinotus grunniens (16%), and Ictalurus punctatus (12%). Annual food consumption of sauger averaged 1.1% of the body weight per day. Growth and daily ration followed similar patterns, being high from September to January (maximum in October) and low from March to August. Rapid growth and high food consumption throughout fall and early winter were related to an extended period of high temperatures and increased availability of Dorosoma cepedianum. The annual period of growth and food consumption was longer and peaked later in the year in the river than those previously observed in other types of aquatic systems.
Search and Stock Depletion: Theory and Applications
Authors: Mangel Marc , Beder Jay H.
Published: October 2008

A general theory for the estimation of stock size from search data is developed. In the theory, it is assumed that discrete aggregations (schools of fish, beds of clams) are encountered. The search model is an extension of the Poisson process to include depletion. The theory provides a way of estimating stock size and confidence intervals around the estimate, as well as the ability to predict future catches for a given level of effort. Three applications of theory are described: (1) estimating stock size when there is no catch; (2) determining, in real time, the length of fishing seasons; and (3) an empirical study of stock assessment of Pacific ocean perch (Sebastes alutus) near Rennell Sound, British Columbia.
Relations Among Net Reproductive Rate and Life History Parameters for Lake Whitefish (Coregonus clupeaformis)
Authors: Jensen A. L.
Published: October 2008

An equation is derived that relates net reproductive rate to six life history parameters; the equation is applied to determine changes in the net reproductive rate of lake whitefish (Coregonus clupeaformis) that result from variation in these life history parameters. Changes in age at maturity and survival of immature fish are the only parameters that have a large effect on the net reproductive rate. Age at maturity occurs near the inflection of the growth curve, and this implies a relationship between age at maturity, length at maturity, the growth coefficient, and asymptotic length.
Effect of Dietary Calcium Phosphate and Zinc Supplementation on Whole Body Zinc Concentration of Rainbow Trout (Salmo gairdneri)
Authors: Hardy Ronald W. , Shearer Karl D.
Published: October 2008

Groups of rainbow trout (Salmo gairdneri) were fed casein–gelatin diets supplemented with calcium phosphate (Ca3(PO4)2) to produce dietary calcium and phosphorus levels of 1,2, or 4% and 0.9,1.5, or 2.4%, respectively (low, medium, or high calcium phosphate), and supplemented with 20 μg Zn/g diet as ZnSO4, zinc proteinate, or ZnSO4 + EDTA (1000 μg/g). Dietary calcium phosphate levels had no significant effect on weight gain of the fish, although the fish fed the high dietary calcium phosphate level were smaller than the rest. Dietary zinc supplementation had no effect on growth, but significantly increased whole body zinc levels in fish fed diets containing low or medium calcium phosphate. In fish fed diets containing low calcium phosphate, the zinc supplements all increased whole body zinc concentrations. In fish fed diets containing medium calcium phosphate, supplementation with zinc proteinate resulted in higher whole body zinc values than supplementation with other zinc sources. Dietary zinc supplementation did not increase whole body zinc concentrations above control levels in fish fed the experimental diets containing high calcium phosphate. We conclude that increased dietary levels of calcium phosphate reduced whole body zinc concentration of rainbow trout and that 20 μg Zn/g diet was insufficient to overcome this reduction at the highest dietary calcium phosphate level regardless of the form of zinc supplement used.
EXCIMER LASER CRYSTALLIZATION AND NANOSTRUCTURING OF AMORPHOUS SILICON FOR PHOTOVOLTAIC APPLICATIONS
Authors: ADIKAARI A. A. D. T. , SILVA S. R. P.
Published: October 2008

Excimer laser crystallization of amorphous silicon has been extensively studied for electronic applications. Most of the early works has been on thin film transistor fabrication from laser crystallized silicon. However, in parallel, the applicability of the technique for photovoltaics has also been pursued. Direct crystallization of the absorber layer of a thin film amorphous silicon cell has proven unsuitable, due to poor device performance. The surface nanostructuring capability of the laser process, as a result of the crystallization appears to be of more scientific significance, and a number of applications have been reported. This review covers the established physics of excimer laser crystallization in the context of photovoltaics. It also expands on more recent applications of excimer laser nanostructuring of amorphous silicon, especially for photovoltaic applications. The outlook of the technique for photovoltaics is discussed with the use of reported successes, briefly discussing the fundamental improvements.
NONLINEAR OPTICAL TRANSMISSION OF SURFACE-MODIFIED NICKEL SULFIDE NANOPARTICLES: SATURATION OF ABSORPTION AND OPTICAL LIMITING
Authors: MUTHUKUMAR V. S. , KIRAN J. K. , REPPERT J. , SATYAJIT R. , KRISHNA VAMSI , RAO G. NAGESHWAR , KRISHNAN S. SIVA RAMA , SAI S. SIVA SANKARA , VENKATARAMANIAH K. , RAO A. M.
Published: October 2008

Saturable absorbers and optical limiters have contrary optical transmission properties. We report observations of simultaneous occurrence of both these effects in a nickel sulfide nanoparticle (average diameter ~5 nm) solution and a simultaneous quantitative measurement of both. Intensity-dependent nonlinear transmission studies carried out using a 7 ns Nd : YAG laser at 532 nm by the Z-scan method, revealed efficient optical limiting in nickel sulfide nanoparticle suspensions. Induced nonlinear optical scattering was identified to be the mechanism of optical limiting, and absorption at 532 nm was found to saturate. A modification of the conventional Z-scan implementation led to the retrieval of the saturation intensity, which is otherwise overshadowed by very strong nonlinear scattering.
ELECTRONIC PROPERTIES OF THIN FILMS SUBLIMED FROMLa@C82ANDLi@C60
Authors: POPOK V. N. , GROMOV A. V. , JÖNSSON M. , TANINAKA A. , SHINOHARA H. , CAMPBELL E. E. B.
Published: October 2008

La @ C82and Li @ C60thin films obtained by sublimation in vacuum are studied using four-probe current–voltage measurements and atomic force microscopy. In situ electrical measurements show semiconducting behavior of both films with room-temperature resistivity of 21 ± 8 and 1230 ± 50 Ω · cm for the La @ C82and Li @ C60, respectively. A variable range hopping mechanism of conductance is suggested from the temperature dependences of resistance. The activation energies for electron transport are calculated for both metallofullerenes. Irreversible changes to the Li @ C60film structure increasing the film resistivity to values typical for C60are found at elevated temperatures. The effect of exposure to ambient atmosphere on the conductance of the films is discussed.
Carbon Nanotube Yarn Actuators: An Electrochemical Impedance Model
Authors: Mirfakhrai Tissaphern , Oh Jiyoung , Kozlov Mikhail , Fang Shaoli , Zhang Mei , Baughman Ray H. , Madden John D. W.
Published: October 2008

Twist-spun yarns made of carbon nanotubes have been shown to work as electrochemical actuators and force sensors. Deep understanding of yarn electrochemical behavior has so far not been possible, in part because of complicated yarn geometry. The electrochemical response of these yarns at different bias potentials was studied using Electrochemical Impedance Spectroscopy and compared with theoretical results for a cylindrical porous electrode. In the evaluated model, distributed capacitors and resistors are used to represent charge storage, electrolyte resistance and parasitic reactions. Resulting predictions are compared with experimental results and the capacitance per unit surface area of the MWNT bundles in the yarn is estimated. The model provides a foundation that can be elaborated upon for engineering applications.
Selective Dispersion of Single-Walled Carbon Nanotubes with Phenylene Based π-Conjugated Polymers
Authors: Zhao Yuming , Rice Nicole , Zhou Ningzhang , Mahmud Ilias
Published: October 2008

Supramolecular interactions between a series of functionalized phenylene based pi-conjugated polymers and two types of as-produced single-walled carbon nanotube (SWNT) samples, namely HiPCO-NTs and CoMoCAT-NTs, were investigated by means of UV-Vis-NIR, Raman spectroscopy, and atomic force microscopic (AFM) analysis. In a non-polar organic solvent (chloroform), the effectiveness of these polymers in selectively dispersing different SWNT components according to electronic type, diameter, and chiral angle was examined and evaluated.
Preparation of the Capsule-like Carbon Tubes via a Facile Solvothermal Route
Authors: Yuan Ding S. , Liu Ying Liang , Chen Liqiang
Published: October 2008

Capsule-like carbon tubes (CLCTs) with a diameter of 300 to 500 nm and a length of 2 to 4 μm have been synthesized via the facile ethanol-thermal route without the presence of toxic reagents. CLCTs have been analyzed and characterized via using by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and Raman spectrum. The analysis results indicate that the graphitic degree of CLCTs is low under our synthesis condition.
Morphology, Acoustic Phonon Confinement, Phonon-induced Strain and Dielectric Permittivity of Nominally Undoped Nano- and Micro-Crystalline Diamond
Authors: Ligatchev Valeri
Published: October 2008

Physical nature of experimentally detected decrease in dielectric permittivity of nano- and micro-crystalline diamond films and powders observed at the grain size diminishment is discussed within frameworks of several well-known approaches. Most of them presume considerable contribution of sp2-coordinated (graphite-like) fraction to dielectric properties of the granular material, which contradicts with available set of corresponding experimental data. An alternative explanation, based on Pekar model and an assumption on dominant contributions of phonon-induced strain and polarization effects of sp3-coordinated intra-granular carbon atoms is proposed. Obtained simulation results are compared with experimentally measured counterparts.
Mass-Production of Passivated CNTFETs: Statistics and Gate-Field Dependence of Hysteresis Effect
Authors: Rispal Lorraine , Tschischke Tobias , Yang Hongyu , Schwalke Udo
Published: October 2008

We present in this work an improvement of our previously reported self-aligned process for carbon nanotube field-effect transistors. The new fabrication process is still based on chemical vapor deposition growth of the nanotubes using a sacrificial catalyst but simplifies the contacting and the passivation of the transistors using only one lithography step. We have fabricated around 15.000 passivated devices and report here on our observations based on measurements of several hundreds of transistors at present.
Extra-Inversion Charge Enhancing Substrate Current During Increased Substrate Bias in 90 nm Process
Authors: Wang Mu-Chun , Hsieh Zhen-Ying , Tu Chia-Hao , Chen Shuang-Yuan , Chen Hung-Wen , Chuang Ai-Erh , Huang Heng-Sheng , Chou Sam
Published: October 2008

Substrate current ISUB depends on source/drain voltage VDS, and can be used as an index of the hot carrier effect (HCE). Normally, substrate bias influences device performance and other parameters, such as the threshold voltage. On the other hand, the substrate biasing circuit benefits turn-on current and restrains the turn-off current. However, few studies assessed the change to substrate current when forcing different drain voltages and substrate biases. Furthermore, a unique phenomenon was observed: separate and consentient trends existed while gate voltage VGS increased from 0 to 1.8 V and a turning point locates around at the peak value of ISUB. Here, this study identifies the increase in surface inversion charge Qi from substrate effect in weak inversion layer more than in strong one; is correlated with this interesting symptom. In this study, gate length LG of a measured n-channel metal-oxide-semiconductor field effect transistor (nMOSFET) device is 0.18 μm with a 90 nm process.
Trimetasphere Metallofullerene MRI Contrast Agents with High Molecular Relaxivity
Authors: MacFarland Darren R.
Published: October 2008

MRI contrast agents derived from Gd3N@C80, termed Hydrochalarones, are described for the first time. Hydrochalarones offer the promise of high relaxivity and safety, and may be used as a platform technology for delivering targeted agents.
Oxoporphyrinogens: From Redox and Spectroscopic Probe for Anion Sensing to a Platform for Construction of Supramolecular Donor-Acceptor Conjugates
Authors: D'Souza F. , Schumacher A. L. , Hill J. P. , Karr P. A. , Xie Y. , Ariga K. , Sandanayaka A. S. D. , Araki Y. , Ito O.
Published: October 2008

Structures and properties of N-alkylated oxoporphyrinogens are presented with an emphasis on their potential application as optical and electrochemical anion sensors, as an electron acceptor in donor-acceptor conjugates, or as a platform to build novel supramolecular donor-acceptor assemblies. Competitive electron transfer from singlet excited zinc porphyrin to either OxP or C60, probed by various time-resolved spectroscopic techniques, in the supramolecular donor-acceptor assemblies was investigated.
New Metal Deposition Methods for Electrocatalysts Syntheses
Authors: Vukmirovic Miomir , Zhang Junliang , Sasaki Kotaro , Li Meng , More Karren , Adzic Radoslav
Published: October 2008

We describe three new methods of metal monolayer/multilayer deposition that make possible syntheses of new types of electrocatalysts for the O2 reduction, and H2 and ethanol oxidation reactions. They consist of a monolayer of Pt deposited on a metal, metal alloy, core-shell, or metal-oxide nanoparticles. The electrocatalysts synthesized using these methods have remarkable properties. For example, for O2 reduction reaction they show up to a 20-fold increase in Pt mass activity compared with conventional all-Pt electrocatalysts. The origin of their increased activity was identified through a combination of experimental methods, employing electrochemical and surface science techniques, X-ray absorption spectroscopy, and density functional theory calculations. The long-term tests in fuel cells demonstrated excellent stability of the anode and good stability of the cathode electrocatalysts. These new electrocatalysts promise to alleviate some of the major problems of existing fuel cell technology.
A Rate of Zinc Potentiostatic Nucleation on a Pyrolytic Carbon Electrode from an Alkaline Solution
Authors: Kryshtop Iurii , Yurchenko Natalya , Trofimenko Vitaliy
Published: October 2008

A method for calculation of an average local rate A¯ of potentiostatic nucleation in an arbitrary time range of an electrode process has been proposed. An example of analysis of Zn nucleation from a zincate electrolyte on a pyrolytic carbon electrode according to Scharifker and Mostany's kinetic model has been used as an illustration of the proposed method. A growth or decrease of A¯ during the nucleation period has been explained by activation of the electrode surface or depletion of more active center of the electrode, respectively.
Pulse Plated Cadmium Telluride Films and Their Characteristics
Authors: Murali K. R. , Rajkumar P. R.
Published: October 2008

CdTe 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 -0.80V(SCE) was employed. The films exhibited polycrystalline cubic structure. XPS spectra exhibit the peaks corresponding to Cd(3d) and Te(3d). Direct band gap of 1.45 eV was obtained. The crystallite size increased from 20 - 60 nm as the duty cycle increased from 10 - 50 %. The films possessed a resistance of 103ohms. A flat band potential of -1.1V(SCE) and a carrier density of 3.5 x 1017 cm-3 was obtained from capacitance measurements.
Features of Zinc Monolayer Electrocrystallization on an Iron Electrode from a Zincate Solution
Authors: Kryshtop Iurii , Yurchenko Natalya , Trofimenko Vitaliy
Published: October 2008

The process of Zn monolayer electrocrystallization on an iron electrode from a zincate electrolyte including the transfer from Zn underpotential deposition (UPD) to Zn phase growth under supersaturation conditions (OPD) has been studied by the galvanostatic potential transient method. In the OPD region, an analysis of potential transients E(t) has been carried out on the basis of the conception of summation of the charge transfer and crystallization overpotentials. OPD of a Zn monolayer from both the pure electrolyte and one containing an inhibiting additive of polymeric tetraalkylammonium salt does not involve nucleation and has been interpreted as development of growth sites formed on a Zn-Fe alloy surface under UPD conditions. An assumption concerning inheritance of peculiarities of Zn intercalation into the Fe crystal lattice by the charge transfer and crystallization stages of Zn monolayer growth during the UPD-OPD transfer has been strengthened.
Pulse Plated CdS Films and Their Photoelectrochemical Behaviour
Authors: Murali K. R. , Thirumurthy P. , Sengodan V.
Published: October 2008

CdS films were deposited by the pulse plating technique at room temperature and at different duty cycles in the range 6 - 50 % using AR grade 0.25M cadmium sulphate and 0.30M sodium thiosulphate. At a deposition potential of -0.75V(SCE). The films exhibited cubic structure. The band gap increased from 3.39 - 2.80 eV as the duty cycle increased. Crystallite size increases from 15 - 50 nm as the duty cycle increased.The resistivity decreased from 19.5 - 9.5 ohm cm as the duty cycle increased from 10 - 50 %. Photoelectrochemical cells yielded an ideality factor of 2.25 and a reverse saturation current of 1.5 x 10-7A cm-2.
Stiffness and relaxation components of the exponential and logistic time constants may be used to derive a load-independent index of isovolumic pressure decay
Authors: Shmuylovich Leonid , Kovács Sándor J.
Published: October 2008

In current practice, empirical parameters such as the monoexponential time constant τ or the logistic model time constant τL are used to quantitate isovolumic relaxation. Previous work indicates that τ and τL are load dependent. A load-independent index of isovolumic pressure decline (LIIIVPD) does not exist. In this study, we derive and validate a LIIIVPD. Recently, we have derived and validated a kinematic model of isovolumic pressure decay (IVPD), where IVPD is accurately predicted by the solution to an equation of motion parameterized by stiffness ( Ek), relaxation (τc), and pressure asymptote (P∞) parameters. In this study, we use this kinematic model to predict, derive, and validate the load-independent index MLIIIVPD. We predict that the plot of lumped recoil effects [ Ek·(P*max − P∞)] versus resistance effects [τc·(dP/d tmin)], defined by a set of load-varying IVPD contours, where P*max is maximum pressure and dP/d tmin is the minimum first derivative of pressure, yields a linear relation with a constant (i.e., load independent) slope MLIIIVPD. To validate the load independence, we analyzed an average of 107 IVPD contours in 25 subjects (2,669 beats total) undergoing diagnostic catheterization. For the group as a whole, we found the Ek·(P*max − P∞) versus τc·(dP/d tmin) relation to be highly linear, with the average slope MLIIIVPD = 1.107 ± 0.044 and the average r2 = 0.993 ± 0.006. For all subjects, MLIIIVPD was found to be linearly correlated to the subject averaged τ ( r2 = 0.65), τL( r2 = 0.50), and dP/d tmin ( r2 = 0.63), as well as to ejection fraction ( r2 = 0.52). We conclude that MLIIIVPD is a LIIIVPD because it is load independent and correlates with conventional IVPD parameters. Further validation of MLIIIVPD in selected pathophysiological settings is warranted.
Myocardial ischemia-mediated excitatory reflexes: a new function for thromboxane A2?
Authors: Fu Liang-Wu , Phan Andrew , Longhurst John C.
Published: October 2008

Clinical and experimental evidence has shown that myocardial ischemia activates cardiac spinal afferents that mediate sympathoexcitatory reflex responses. During myocardial ischemia, thromboxane A2 (TxA2) is released in large quantities by activated platelets in the coronary circulation of patients with coronary artery disease. We hypothesized that endogenous TxA2 contributes to sympathoexcitatory reflexes during myocardial ischemia through stimulation of TxA2/prostaglandin endoperoxide (TP) receptors. Regional myocardial ischemia was induced by occlusion of a diagonal branch of left anterior descending coronary artery of anesthetized cats. Hemodynamic parameters and renal sympathetic nerve activity were recorded after sinoaortic denervation and bilateral vagotomy. Regional myocardial ischemia evoked significant increases in mean blood pressure (122 ± 10 vs. 139 ± 12 mmHg, before vs. ischemia), aortic flow (153 ± 18 vs. 167 ± 20 ml/min), first derivative of left ventricular pressure at 40-mmHg developed pressure (2,736 ± 252 vs. 2,926 ± 281 mmHg/s), systemic vascular resistance (0.6 ± 0.1 vs. 0.9 ± 0.12 peripheral resistance units), and renal sympathetic nerve activity (by 22%). The reflex nature of the excitatory responses was confirmed by observing its disappearance after blockade of cardiac nerve transmission with intrapericardial 2% procaine treatment. Moreover, application of U-46619 (2.5–10 μg), a TxA2 mimetic, on the heart caused graded increases in mean arterial pressure and renal nerve activity, responses that were abolished 3 min after local blockade of cardiac neural transmission with intrapericardial procaine. BM 13,177 (30 mg/kg iv), a selective TP receptor antagonist, eliminated the reflex responses to U-46619 and significantly attenuated the excitatory responses during brief (5 min) regional myocardial ischemia. The sympathoexcitatory reflex responses to U-46619 were unchanged by blockade of histamine H1 receptors with pyrilamine and serotonin 5-HT3 receptors with tropisetron, indicating specificity of this TP receptor agonist. These data indicate that endogenous TxA2 participates in myocardial ischemia-mediated sympathoexcitatory reflex responses through a TP receptor mechanism.
Fluid and electrolyte supplementation after prolonged moderate-intensity exercise enhances muscle glycogen resynthesis in Standardbred horses
Authors: Waller Amanda P. , Heigenhauser George J. F. , Geor Raymond J. , Spriet Lawrence L. , Lindinger Michael I.
Published: October 2008

We hypothesized that postexercise rehydration using a hypotonic electrolyte solution will increase the rate of recovery of whole body hydration, and that this is associated with increased muscle glycogen and electrolyte recovery in horses. Gluteus medius biopsies and jugular venous blood were sampled from six exercise-conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum, and either a hypotonic commercial electrolyte solution (electrolyte) via nasogastric tube, followed by a typical hay/grain meal, or a hay/grain meal alone (control). The CET resulted in decreased total body water and muscle glycogen concentration of 8.4 ± 0.3 liters and 22.6%, respectively, in the control treatment, and 8.2 ± 0.4 liters and 21.9% in the electrolyte treatment. Electrolyte resulted in an enhanced rate of muscle glycogen resynthesis and faster restoration of hydration (as evidenced by faster recovery of plasma protein concentration, maintenance of plasma osmolality, and greater muscle intracellular fluid volume) during the recovery period compared with control. There were no differences in muscle Na, K, Cl, or Mg contents between the two treatments. It is concluded that oral administration of a hypotonic electrolyte solution after prolonged moderate-intensity exercise enhanced the rate of muscle glycogen resynthesis during the recovery period compared with control. It is speculated that postexercise dehydration may be one key contributor to the slow muscle glycogen replenishment in horses.
Modeling the dynamics of recruitment and derecruitment in mice with acute lung injury
Authors: Massa Christopher B. , Allen Gilman B. , Bates Jason H. T.
Published: October 2008

Lung recruitment and derecruitment contribute significantly to variations in the elastance of the respiratory system during mechanical ventilation. However, the decreases in elastance that occur with deep inflation are transient, especially in acute lung injury. Bates and Irvin ( 8 ) proposed a model of the lung that recreates time-varying changes in elastance as a result of progressive recruitment and derecruitment of lung units. The model is characterized by distributions of critical opening and closing pressures throughout the lung and by distributions of speeds with which the processes of opening and closing take place once the critical pressures have been achieved. In the present study, we adapted this model to represent a mechanically ventilated mouse. We fit the model to data collected in a previous study from control mice and mice in various stages of acid-induced acute lung injury ( 3 ). Excellent fits to the data were obtained when the normally distributed critical opening pressures were about 5 cmH2O above the closing pressures and when the hyperbolically distributed opening velocities were about an order of magnitude greater than the closing velocities. We also found that, compared with controls, the injured mice had markedly increased opening and closing pressures but no change in the velocities, suggesting that the key biophysical change wrought by acid injury is dysfunction of surface tension at the air-liquid interface. Our computational model of lung recruitment and derecruitment dynamics is thus capable of accurately mimicking data from mice with acute lung injury and may provide insight into the altered biophysics of the injured lung.
Changes of surface and t-tubular membrane excitability during fatigue with repeated tetani in isolated mouse fast- and slow-twitch muscle
Authors: Cairns Simeon P. , Taberner Andrew J. , Loiselle Denis S.
Published: October 2008

We investigated whether impaired sarcolemmal excitability causes severe fatigue during repeated tetani in isolated mouse skeletal muscle. Slow-twitch soleus or fast-twitch extensor digitorum longus (EDL) muscles underwent intensive stimulation (standard protocol: 125 Hz for 500 ms, every second, parallel plate electrodes, 20 V, 0.1-ms pulses). Interventions with altered stimulation characteristics were tested either on the entire fatigue profile or after 90- to 100-s stimulation. d-tubocurarine did not alter the fatigue profile in soleus thereby eliminating impaired neuromuscular transmission. Lower stimulation frequencies partially restored peak force, especially in soleus. The twitch force-stimulation strength relationship shifted towards higher voltages in both muscle types, with a much larger shift in EDL. Augmenting pulse strength restored tetanic force from 29% (4.4 V) to 79% (20 V), or slowed fatigue in soleus. Increasing pulse duration (0.1 to 1.0 ms) restored tetanic force from 8 to 46% in EDL and from 41 to 90% in soleus; 0.25-ms pulses restored tetanic force to 83% in soleus. Switching from transverse wire to parallel plate stimulation increased tetanic force from 34 to 63%, and fatigue was exacerbated with wires compared with plates in soleus. The combined data suggest that impaired excitability (disrupted action potential generation) within trains is the main contributor (∼50% initial force) to severe fatigue in both muscle types, the surface rather than t-tubular membrane is the main site of impairment during wire stimulation, and extreme fatigue in EDL includes an increased action potential threshold leading to inexcitable fibers. Moreover, mathematical modeling discounts anoxia as the major contributor to fatigue during our stimulation regime in isolated muscles.
Altered contractile properties of the gastrocnemius muscle poststroke
Authors: Gao Fan , Zhang Li-Qun
Published: October 2008

Spasticity, contracture and muscle weakness often occur together poststroke and cause considerable motor impairments to stroke survivors. The underlying changes in contractile properties of muscle fascicles are still not clear. The purpose of this study was to investigate the contractile property changes of the medial gastrocnemius muscle fascicles poststroke. Ten stroke survivors and ten healthy subjects participated in the study. The medial gastrocnemius fascicular length was measured at various combinations of ankle and knee positions using ultrasonography, with the muscle activated selectively using electrical stimulation. The stimulation intensity was kept constant across different ankle and knee positions to establish the active force-length relationship of the muscle fascicles. It was found that stroke survivors showed a shift of the force-length curve with a significantly shorter optimal fascicle length (33.2 ± 3.2 mm) compared with that of healthy controls (47.4 ± 2.7 mm) with P < 0.001. Furthermore, the width span of the fascicular force-length curve of stroke survivors was significantly narrower with steeper slopes than that of controls ( P ≤ 0.001), suggesting reduced number of sarcomeres along the fascicles and/or reduced sarcomere length poststroke. Regression analysis showed that the medial gastrocnemius fascicular length of stroke survivors varied significantly less with ankle and knee flexions ( P ≤ 0.001) than that of controls, suggesting shorter and stiffer muscle fascicles poststroke, which might be attributed to muscle architectural adaptation. This study showed that there are considerable changes in the contractile properties of muscle fascicles poststroke, which may contribute directly to the joint-level changes of decreased range of motion, increased stiffness, muscle weakness, and impaired motor functions in stroke survivors.