bluuebunny/crossref_metadata_2025_split huggingface dataset:
INTERACTION OF MARINE SEDIMENTS WITH DISSOLVED SILICA1
Authors: Fanning Kent A. , Schink David R. 
Published: March 2010

A sample of Atlantic sea floor sediment released SiO2 in amounts greater than expected when placed in contact with silica‐poor seawater but failed to reduce the concentration of enriched (211 μm) seawater. In situ, these sediments had been in contact with seawater containing 30‐µm silica. The interstitial water from the core held 210‐µm silica, suggesting that clay‐silica equilibria control this concentration. If this interstitial silica were derived from resolution of clay minerals, then clay‐silica equilibria would be a major source of dissolved silica in the Atlantic Ocean. It is far more likely that the resolution of biological silica accounts for the bulk of the interstitial content and this mechanism might explain the high silica concentrations found in cores from productive regions. In barren areas, the lower interstitial concentrations may be regulated by clay‐silica equilibria.The relative amounts of dissolved silica entering the oceans (~4 × 1014 g/yr) compared to the amount of pelagic clay sedimentation (~2 × 1015 g/yr) indicate that clay—if it were the major agent of removal—would have to contain 20% hydrogenous silica, whereas the maximum demonstrated adsorption is about 2%. It seems impossible that adsorption on clays is the prime agent for extraction of silica from the present oceans.
THE RELATIONSHIP BETWEEN ORGANIC NITROGEN AND THE CAROTENOID TO CHLOROPHYLL a RATIO IN FIVE FRESHWATER PHYTOPLANKTON SPECIES1
Authors: Manny Bruce A. 
Published: March 2010

A linear relationship of positive slope was found between the ratios of organic nitrogen: chlorophyll a and total carotenoids: chlorophyll a in cultures of five freshwater phytoplankters as they recovered from N‐deficiency. This differed markedly from information in the literature for a marine diatom under similar conditions.This relationship in cultures of a freshwater diatom was not significantly different from one calculated from data in the literature for a N‐deficient natural population of marine diatoms. Therefore it is suggested that, under conditions of limiting nitrogen, the natural ratio of plant pigments can he used in conjunction with the nitrogen: pigment relationship to estimate the quantity of nitrogen in natural phytoplankton as distinct from other sources of particulate nitrogen in surface waters.
NITRATE REDUCTION IN SEAWATER OF THE DEEP NITRITE MAXIMUM OFF PERU1
Authors: Carlucci A. F. , Schubert Hazel R. 
Published: March 2010

Nitrate‐reducing bacteria were isolated from samples collected inside and outside the secondary nitrite maximum in oxygen‐poor deep waters off the coast of Peru. Under anaerobic conditions at 20C in the laboratory, these bacteria reduced nitrate to nitrite in seawater enriched with 0.5 to 1.0 mg glucose/liter. Nitrate reduction also occurred in seawater supplemented only with 20 µg‐atom NO3−‐N/liter and trace metals. Nitrite production generally was greatest during the first 24 hr while cell numbers were increasing. On continued incubation cells died, nitrate increased, and nitrite decreased. Dissolved organic carbon increased concurrently with the death of bacteria, indicating release of cell contents into the medium by lysis.Microbiological evidence is presented to show that the high nitrite concentrations in oxygen‐poor deep waters of the secondary nitrite maximum arise from nitrate reduction.
SOME PHOTOSYNTHETIC CHARACTERISTICS OF A NATURALLY OCCURRING POPULATION OF OSCILLATORIA AGARDHII GOMONT1,2
Authors: Baker A. L. , Brook A. J. , Klemer A. R. 
Published: March 2010

A natural metalimnetic population of the filamentous blue‐green Oscillatoria agardhii showed diurnal variation in net production of oxygen. The population was incubated during a series of 2‐hr periods during daylight hours on 7 August 1967, while suspended at several depths in Lake Itasca, Minnesota (47° N lat, 95° W long). The net rate of oxygen production varied with light intensity, reaching light saturation at near 10% of the maximum insolation (the incident intensity, I0, at solar noon). Productivity curves for depths corresponding to 100, 60, 30, 17, 11, 6, and 4% I° were obtained. High rates of production occurred during twilight at the surface, but near solar noon at the 6 and 4% levels. The variation, over the range of depths investigated, of oxygen per unit volume represents the shape of a photosynthesis‐depth profile for a homogeneously distributed population. The highest production is at 30% I0.The rate‐light intensity curve for the Oscillatoria population is similar in shape to that for certain cultures of marine algae, using the 14C technique. Distribution of points on the rate‐light intensity curve suggests that light quality, as well as intensity, is important, and that the filtering effect of lake water enhances subsurface oxygen production even at relatively high light intensities (80% of the solar noon I0 value).
FORAMINIFERAL SPECIES DENSITIES AND ENVIRONMENTAL VARIABLES IN AN ESTUARY
Authors: Buzas Martin A. 
Published: March 2010

A pilot study of foraminiferal species densities in the Choptank River, Maryland, a part of the Chesapeake Bay estuarine system, indicated that the density of Elphidium clavatum decreased progressively upstream, while the densities of Ammobaculites exiguus and Ammonia beccarii varied little. Three stations were selected for more detailed analysis.Each station was sampled monthly for foraminiferal density for 12 months, and temperature, salinity, oxygen, and chlorophyll a, b, and c were measured. A general multiple regression‐analysis of variance model containing parameters for environmental variables, station differences, overall periodic differences, and the interaction of station and periodic differences was statistically compared to several more restricted models, with separate analyses for each species.The set of environmental variables is significant at the 95% level for all three species. None of the variables is significant individually. However, the relatively large values of the regression coefficients for the chlorophylls, especially b, suggest that the amount and kind of available food is important in determining species densities.All three species exhibit periodicity, and for each species the periodicity is different at the three stations. Restricted models containing 15 parameters are sufficient to account for the observed species densities in each case.
THE OSMOTIC ADAPTATION OF THE FAIRY SHRIMP BRANCHINECTA CAMPESTRIS LYNCH TO SALINE ASTATIC WATERS1
Authors: BROCH EDMUND S. 
Published: March 2010

The fairy shrimp Branchinecta campestris was found in association with Artemia salina (L.) in four saline astatic lakes in Okanogan County, Washington, and in British Columbia. In all four lakes sulfate was the predominant ion making up in milliequivalence 48% of the total ions. The predominant cations sodium and magnesium occurred in varying proportions. The osmotic concentration of Penley Lake from hatching to death of the adult population of B. campestris increased progressively from 36 to 660 mOsm/liter. At concentrations of 286 mOsm/liter and less, B. campestris regulates hyperosmotically. However, from 451 to 660 mOsm/liter B. campestris is poikiloosmotic and not a hypoosmotic regulator like A. salina. Therefore, its ability to live in saline astatic waters can be partly attributed to tolerance of a high hemolymph concentration.Coexistence between A. salina and B. campestris is brief. B. campestris is restricted to the early phase of the saline astatic lake, characterized by low but increasing salinity and temperature, whereas A. salina appears a month later and is restricted to the high salinity‐temperature phase of the lake. Factors responsible for temporal separation of these two species appear to be differences in osmoregulation and in factors regulating development and hatching.
RELEASE OF DISSOLVED ORGANIC MATTER BY MARINE SEAWEEDS AND DISTRIBUTION OF THEIR TOTAL ORGANIC PRODUCTION TO INSHORE COMMUNITIES1
Authors: Khailov K. M. , Burlakova Z. P. 
Published: March 2010

Under controlled experimental conditions, release rates of organic matter were estimated for five species of Barents Sea macrophytes and for thirteen species of Black Sea macrophytes. The release rates of different species from the Barents Sea were between 0.9 and 2.9 mg of organic matter per gram (dry wt) of plants per hour (mg g−1 hr−1) in March and between 1.7 and 9.8 mg g−1 hr−1 in June. The release rates of different species from the Black Sea were between 1.25 and 6.1 mg g−1 hr−1 in fast growing plants and between 0.5 and 1.6 mg g−1 hr−1 in slowly growing plants.Approximate quantities of total dissolved organic matter released per year have been calculated to be about 39% of gross production in brown algae, about 38% in red algae, and about 23% in green algae. The rest of the organic matter was released during decomposition of that part of standing stock not consumed by herbivorous animals. About 30% of gross production may be released in this way. Thus, the total flow of dissolved organic matter from seaweeds during growth and after death may be as much as 70% of their gross production.The ecological significance of external organic metabolites released in the surrounding water is discussed.
NEOMYSIS AWATSCHENSIS IN THE SACRAMENTO‐SAN JOAQUIN RIVER ESTUARY
Authors: Heubach William 
Published: March 2010

The opossum shrimp Neomysis awatschensis was collected systematically from Suisun Bay and the Sacramento and San Joaquin Rivers from March 1965 to Scptember 1966. Population densities were highest in summer from freshwater downstream to 4.0‰ chlorinity. Reproduction was greatest in spring and summer from the lowermost freshwater stations to 2.0‰ Cl and was the principal factor affecting seasonal and geographical abundance.Mysid densities were lowest where chlorinity was greater than 10.0‰, little or no flow reversal occurred during floodtide, and light intensity in the water exceeded 10−5 lux. Water temperatures over 22C in combination with less than 8 ppm dissolved oxygen appear unfavorable to N. awatschensis. Tide and water velocity affected vertical distribution while light influenced both lateral and vertical distribution.
Eh AS AN OPERATIONAL, PARAMETER IN ESTUARINE STUDIES
Authors: Whitfield M. 
Published: March 2010

Quantitative interpretation of Eh measurements in natural aqueous systems is difficult because of problems associated with the technique of measurement, the performance of the inert metal electrode, and the thermodynamic behavior of the environment. However, the parameter is useful as a semiquantitative indicator of the degree of stagnation of a particular environment.A compound probe is described that reduces the technical problems and enables pH, Eh, and pS2− measurements to be made simultaneously on a single sample. With this probe, Eh can be used as an operational parameter to map the distribution of estuarine sediments.
BODY NITROGEN AND NITROGENOUS EXCRETION IN NEOMYSIS RAYII MURDOCH AND EUPHAUSIA PACIFICA HANSEN1
Authors: Jawed Mohammad 
Published: March 2010

The rates of nitrogenous excretion in the form of ammonia, amino acids, urea, and total nitrogen are determined for Neomysis rayii and Euphausia pacifica at two temperatures, 10 and 4C. Temperature has a marked effect on the excretory rates. Ammonia‐N is the dominant form of excretion in both species (72–87% of nitrogen excreted), and the amounts of amino nitrogen excreted by both organisms are much lower than reported by earlier authors for other zooplankton. There is evidence that amino‐N is excreted below 6C. Small quantities of urea are excreted by Euphausia pacifica only.Neomysis rayii excretes 25 µg N/mg body nitrogen per day at 10C and 15 µg N/mg body nitrogen per day at 4C. Euphausia pacifica excretes 21 µg N/mg body nitrogen per day at 10C and 12 µg at 4C. While starved, these species catabolize proteins almost exclusively and lose about 2% of body protein per day.
THE OCEANIC SHRIMP SERGESTES SIMILIS OFF THE OREGON COAST1
Authors: Pearcy W. G. , Forss Carl A. 
Published: March 2010

Sergestes similis is the most abundant pelagic shrimp in modified subarctic waters off Oregon and the northeastern Pacific Ocean. Off Oregon, its distribution changes with season and distance from shore. Largest numbers were caught in waters over the continental slope in 6‐ft midwater trawls and 1‐m plankton nets. Smallest catches were over the shelf and greater than 65 nm (120 km) offshore. Largest nearshore catches were made during winter, largest offshore catches during summer.Observations on the size of eggs in ovaries, the percentage of females with mature eggs, and the catches of young shrimp all indicated that spawning of the S. similis population is prolonged through most of the year. Young shrimp were not uniformly abundant, however, suggesting pulses of spawning in winter and spring.Growth rates and age structure estimates from length‐frequency histograms implied that the population is largely comprised of animals of age‐group 0. Individuals mature sexually after about one year when they attain a carapace length of 11 mm. Large individuals over 12 mm are rare and may die after spawning.
HALF‐SATURATION CONSTANTS FOR UPTAKE OF NITRATE AND AMMONIUM BY MARINE PHYTOPLANKTON1
Authors: Eppley Richard W. , Rogers Jane N. , McCarthy James J. 
Published: March 2010

Uptake rate of nitrate and ammonium was studied as a function of nitrate or ammonium concentration with cultures of 16 species of marine phytoplankton. Half‐saturation constants (the concentration supporting an uptake rate one‐half the maximum rate) were computed as a measure of the ability of a species to use low levels of nitrate and ammonium. The half‐saturation constant (Ks) varied approximately in proportion to cell size and inversely with specific growth rate. Small‐celled oceanic species, such as Coccolithus huxleyi, showed the lowest K8 values (⩽0.5μm) and Gonyaulax polyedra the highest (Ks > 5 µm). The Ks values are considered to be important characteristics of organisms living in nitrogen‐limited environments.Some apparent success was achieved in predicting the competitive advantage of one species over another by calculating specific growth rates as functions of nitrate and ammonium concentration for species with known growth response to irradiance, temperature, and daylength. For example, at about 20C and 16 hr daylength C. huxleyi should be able to compete successfully with Skeletonema costatum when nitrate, ammonium, and irradiance are low. Skeletonema costatum should grow faster than C. huxleyi only when irradiance and nitrate or ammonium are fairly high. Rock pool forms appear to be relatively unsuccessful in the ocean because of a sluggish response to irradiance and not because of an inability to use low levels of nitrate and ammonium. The success of G. polyedra, often the dominant dinoflagellate in local red water blooms, appears to be due to its vertical migration from the sea surface in daylight to nitrate‐rich water at 10‐15‐m depth at night, rather than to any special ability to grow rapidly or use low levels of nitrate and ammonium.
DIURNAL MIGRATION IN THREE SPECIES OF ROTIFERS IN SUNFISH LAKE, ONTARIO
Authors: George M. G. , Fernando C. M. 
Published: March 2010

The pattern of diurnal migration in three species of rotifers has been studied from six 24‐hr samples obtained in different months to cover a wide range of seasonal conditions. Velocities and amplitude of vertical migration were calculated for the three species.The same species can show nocturnal upward migration at one season and the reverse at another. There are differences in vertical movements during ice cover. There is some indication that different species exhibit diurnal migration keeping different zonation.
N‐terminal fusion of a hyperthermophilic chitin‐binding domain to xylose isomerase from Thermotoga neapolitana enhances kinetics and thermostability of both free and immobilized enzymes
Authors: Harris James M. , Epting Kevin L. , Kelly Robert M. 
Published: March 2010

AbstractImmobilization of a thermostable D‐xylose isomerase (EC 5.3.1.5) from Thermotoga neapolitana 5068 (TNXI) on chitin beads was accomplished via a N‐terminal fusion with a chitin‐binding domain (CBD) from a hyperthermophilic chitinase produced by Pyrococcus furiosus (PF1233) to create a fusion protein (CBD‐TNXI). The turnover numbers for glucose to fructose conversion for both unbound and immobilized CBD‐TNXI were greater than the wild‐type enzyme: kcat (min−1) was ∼1,000, 3,800, and 5,800 at 80°C compared to 1,140, 10,350, and 7,000 at 90°C, for the wild‐type, unbound, and immobilized enzymes, respectively. These kcat values for the glucose to fructose isomerization measured are the highest reported to date for any XI at any temperature. Enzyme kinetic inactivation at 100°C, as determined from a bi‐phasic inactivation model, showed that the CBD‐TNXI bound to chitin had a half‐life approximately three times longer than the soluble wild‐type TNXI (19.9 hours vs. 6.8 hours, respectively). Surprisingly, the unbound soluble CBD‐TNXI had a significantly longer half‐life (56.5 hours) than the immobilized enzyme. Molecular modeling results suggest that the N‐terminal fusion impacted subunit interactions, thereby contributing to the enhanced thermostability of both the unbound and immobilized CBD‐TNXI. These interactions likely also played a role in modifying active site structure, thereby diminishing substrate‐binding affinities and generating higher turnover rates in the unbound fusion protein. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Treatment engagement as a predictor of premature treatment termination and treatment outcome in a correctional outpatient sample
Authors: Drieschner Klaus H. , Verschuur Joop 
Published: March 2010

AbstractBackground It is widely assumed that the outcome of correctional treatment largely depends on the patient's treatment engagement; however, evidence for this notion is scarce.Aim In this study, the Treatment Engagement Rating scale (TER) was used to investigate the relationship of a patient's treatment engagement with premature treatment termination and treatment outcome, defined as reduction of the risk of reoffending.Method Employing a prospective design, this study addressed the relationship of the behavioural treatment engagement of correctional outpatients (N = 138) with treatment non‐completion and treatment outcome, respectively.Results Treatment engagement as measured by the TER emerged as an accurate predictor of treatment non‐completion (area under the curve = 0.76; odds ratio = 4.1) and was also significantly correlated with treatment outcome (ρ = 0.41). The prediction was more accurate for sex offenders than for violent offenders, for expulsion from the treatment than for dropout, and when treatment engagement was assessed closer to the end of the treatment.Conclusions The study provides evidence that the outcome of correctional treatment depends to a substantial degree on the behavioural efforts that the patients make for the treatment. Periodic assessment of treatment engagement in correctional treatment facilities would be useful, and the TER seems to be a practical, reliable and valid instrument for this purpose. Copyright © 2010 John Wiley & Sons, Ltd.
Prevention of polyurethane oxidative degradation with phenolic antioxidants covalently attached to the hard segments: Structure–function relationships
Authors: Stachelek Stanley J. , Alferiev Ivan , Ueda Masako , Eckels Edward C. , Gleason Kevin T. , Levy Robert J. 
Published: March 2010

AbstractOxidative degradation of the polyurethane elastomeric (PU) components greatly reduces the efficacy of PU‐containing cardiovascular devices. Covalently appending the phenol‐based antioxidant, 4‐substituted 2,6‐di‐tert‐butylphenol (DBP), to PU hard segments effectively reduced oxidative degradation of the PU in vivo and in vitro in prior studies by our group. In these experiments, we analyze the contribution of the tethering molecule to the antioxidant capabilities of the DBP‐modified PU. Bromoalkylation chemistry was used to link DBP to the hard segment of the polyether PU, Tecothane, via our original linker (PU‐DBP) or variants containing side chains with one (PU‐C‐DBP) or three (PU‐3C‐DBP) carbons. Two additional DBP variants were fabricated in which the DBP group was appended to the alkyl chain via an oxygen atom (PU‐O‐DBP) or an amide linkage in the middle of the tether (PU‐NHCO‐DBP). All DBP variant films and unmodified control films were subject to oxidative degradation via 15‐day immersion in a solution of 20% H2O2 + 0.1M CoCl2. At the end of the oxidation protocol, films were analyzed for the presence of oxidation‐related endpoints via scanning electron microscopy, contact angle measurements, and Fourier transformation infrared spectroscopy (FTIR). All DBP‐containing variants resisted oxidation damage significantly better than the unmodified control PU. SEM analysis of oxidized PU‐C‐DBP and PU‐O‐DBP showed evidence of surface cracking, consistent with oxidative degradation of the PU surfaces. Similarly, there was a trend in increased ether crosslinking, a marker for oxidative degradation, in PU‐C‐DBP and PU‐NHCO‐DBP films. Consistent with these FTIR results, both PU‐C‐DBP and PU‐NHCO‐DBP had significant reductions in measured surface hydrophobicity as a result of oxidation. These data show for the first time that the choice of linker molecule significantly affects the efficiency of the linked phenolic antioxidant. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010
Calibration issues for nanoindentation experiments: Direct atomic force microscopy measurements and indirect methods
Authors: Barone A.C. , Salerno M. , Patra N. , Gastaldi D. , Bertarelli E. , Carnelli D. , Vena P. 
Published: March 2010

AbstractThis article discusses calibration issues for shallow depth nanoindentation experiments with Berkovich tips with respect to the accurate measurement of the diamond area function (DAF). For this purpose, two different calibration procedures are compared: (i) the direct measurement of the DAF through atomic force microscopy (AFM) imaging of the Berkovich tip at shallow depth and (ii) a novel indirect calibration method based on an iterative robust and converging scheme in which both reduced modulus and indentation hardness are simultaneously used. These results are obtained by indentation measurements on a standard specimen of fused silica, performed in the 0.5–200 mN load range with a Berkovich indenter. Direct tip shape measurements were carried out through different AFM methods. Comparisons with the standard indirect calibration procedure are also reported. For both the indirect calibration procedures a sensitivity and convergence study is presented. Microsc. Res. Tech. 73:996–1004, 2010. © 2010 Wiley‐Liss, Inc.