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  • Animals  (443)
  • Kinetics  (48)
  • Gas chromatography  (32)
  • Pregnancy  (30)
  • sediment  (29)
  • American Association for the Advancement of Science (AAAS)  (462)
  • Springer  (71)
  • 1980-1984  (533)
  • 1925-1929
  • 1982  (533)
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  • American Association for the Advancement of Science (AAAS)  (462)
  • Springer  (71)
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  • 1980-1984  (533)
  • 1925-1929
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  • 1
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    Colloid & polymer science 260 (1982), S. 641-642 
    ISSN: 1435-1536
    Keywords: Kinetics ; Nucleation ; Water ; Emulsion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 2
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    Monatshefte für Chemie 113 (1982), S. 1087-1092 
    ISSN: 1434-4475
    Keywords: Dissolution ; Kinetics ; Pyrrhotite ; Rotating disc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Auflösungsgeschwindigkeit von natürlichem monoklinen Pyrrhotin, FeS1.14, wurde in sauerstofffreien LösungenS([H+]=0.1, [Na+]=0.9, [ClO 4 − ]=1.0 mol kg−1) mit Hilfe der Methode der rotierenden Scheibe bestimmt. Im Temperaturbereich von 40–90° erfolgt die Auflösungsreaktion kinetisch kontrolliert, wobei eine Aktivierungsenergie von 14±1 kcal mol−1 (59±5 kJ mol−1) gefunden wurde.
    Notes: Abstract Using the rotating disc method, the rates of dissolution of natural monoclinic pyrrhotite, FeS1.14, in oxygen-free aqueous solutionsS([H+]=0.1, [Na+]=0.9, [ClO 4 − ]=1.0 mol kg−1) were determined. In the temperature range 40–90 °C the dissolution reaction occurs under kinetic control; the activation energy being 14±1 kcal mol−1 (50±5 kJ mol−1).
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  • 3
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    Monatshefte für Chemie 113 (1982), S. 1239-1244 
    ISSN: 1434-4475
    Keywords: Allyl alcohol ; Kinetics ; Mechanism ; Oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Kinetik der Oxidation von Allylalkohol mitN-Bromsuccinimid (NBS) wurde bei 35 °C in wäßrigem Medium untersucht. Die Reaktion zeigt erste Ordnung gegenüberNBS und Allylalkohol. Bei relativ hoher Säurekonzentration zeigt sich keine Änderung der Reaktionsgeschwindigkeit, bei niedriger Säurekonzentration wird die Reaktionsgeschwindigkeit beträchtlich erhöht. Es wurde kein primärer Salzeffekt festgestellt. Bei varriierender Quecksilberacetatkonzentration bleibt die Reaktionsgeschwindigkeit gleich, bei Abwesenheit von Quecksilberacetat wird jedoch die Geschwindigkeitskonstante erhöht. Die kinetischen Parameter,E a, derArrheniusfaktorA, ΔH ≠, ΔG ≠ und ΔS ≠ wurden bestimmt. Ein Geschwindigkeitsgesetz in Übereinstimmung mit den experimentellen Befunden wurde abgeleitet und ein Mechanismus vorgeschlagen.
    Notes: Abstract The kinetics of oxidation of allyl alcohol byN-bromosuccinimide (NBS) has been studied at 35 °C in aqueous medium. The reaction shows first order dependence on bothNBS and allyl alcohol. In fairly high acid concentration, there is no change in the rate of the reaction but at low acid concentration, the rate is considerably enhanced. There is no primary salt effect. At varying mercuric acetate concentrations, the rate constant remains the same. But in the absence of mercuric acetate, the rate is enhanced. The kinetic parameters,E a,Arrhenius factorA, ΔH≠, ΔG≠ and ΔS≠ have been calculated. A rate law in agreement with experimental results has been derived. A mechanism is proposed.
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  • 4
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    Monatshefte für Chemie 113 (1982), S. 887-893 
    ISSN: 1434-4475
    Keywords: Diazotation ; Kinetics ; α-Naphthylamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Optimal diazotation conditions were determined by means of extinction measurements at various experimental conditions. The optimal conditions found arep H=9,5, the amount of phenol is 1 250 times the amount of α-naphthylamine.
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  • 5
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    Monatshefte für Chemie 113 (1982), S. 3-14 
    ISSN: 1434-4475
    Keywords: Graphite ; Kinetics ; Reduction ; Thoria ; Thoriumcarbide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Reduktion von Thoriumoxid mit Graphit im Überschuß wurde mittels einer Thermowaage zwischen 1620 und 1920 K im Vakuum untersucht. Ab ThO2:C=1:50 war die Reaktionsgeschwindigkeit vom Mischungsverhältnis unabhängig; das Endprodukt war immer ThC2. Der logarithmische Gewichtsverlust war direkt proportional der Zeit, und dieArrheniusgerade zeigte einen Knickpunkt bei 1710 K: unterhalb dieser Temperatur ergab sich eine Aktivierungsenergie von 440 kJ, oberhalb eine solche von 260 kJ. Die Temperatur des Knickpunkts entspricht der Umwandlungstemperatur von monoklinem in tetragonal raumzentriertes ThC2.
    Notes: Abstract The reduction of thoria with excess graphite was studied with a thermo-balance in vacuum between 1620 and 1920 K. From Th02:C=1:50 the rate of reaction was independent of the ratio of the reactants; the endproduct was always ThC2. The logarithmic weight loss was directly proportional to the time, and theArrhenius plot showed a break at 1710 K: below this temperature the activation energy was found to be 440 kJ, above 260 kJ. The temperature corresponding to the break coincides with the transition temperature of monoclinic to body-centered tetragonal ThC2.
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  • 6
    ISSN: 1434-4475
    Keywords: Kinetics ; Ligand-transfer ; Thallium (III)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The transfer of oxinate ions from thallium (III)oxinate to trivalent Fe(DMF) 6 3+ in propylenecarbonate takes place via rearrangements within a rapidly formed binuclear thallium(III)—iron(III) complex. In a last rapid step this rearranged complex reacts with excess reactants to the final products whose composition accordingly depends on the ratio of the reactant concentrations.
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  • 7
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    Calcified tissue international 34 (1982), S. 9-12 
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Pregnancy ; Nephrogenous cAMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parathyroid hormone (PTH) metabolism in pregnancy has not been clearly defined. Studies have reported either increased or unchanged values of immunoreactive PTH (iPTH). However, iPTH levels do not necessarily correlate with hormonal bioactivity due to the presence of immunoreactive but nonbioactive PTH fragments. In this study we evaluated PTH metabolism in the third trimester of pregnancy by determining iPTH blood levels as well as the biological effects of PTH, assessed by tubular maximum phosphate reabsorption (TmP) and nephrogenous cAMP (ncAMP) excretion, in 10 young, healthy pregnant patients (mean gestational age 35 weeks) and 10 young, healthy age-matched female controls. Pregnancy was associated with a significant increase in creatinine clearance (146±13 vs 106±9 ml/min,P〈0.01), and a significant decrease in total fasting serum calcium (8.4±0.1 vs 9.0±0.1 mg/dl,P〈0.001) and serum albumin (3.6±0.1 vs 4.2±0.1 g/dl,P〈0.001). There was no significant difference in iPTH (3.7±0.4 vs 4.3±0.5 µlEq/ml), serum phosphorus (3.6±0.1 vs 3.8±0.2 mg/dl), TmP (3.61±0.13 vs 3.75±0.25 mg/100 ml GFR), or ncAMP (1.68±0.20 vs 1.88±0.23 nmoles/100 ml GFR) between the two groups. Pregnancy was attended by a significant increase in fasting urinary calcium to creatinine ratio (0.14±0.03 vs 0.06±0.01,P〈0.05), an index of bone resorption. The data suggest that the biological effects of PTH are unchanged in pregnancy, and that reported increments in 1,25(OH)2 vitamin D in pregnancy are not regulated by changes in either PTH, calcium, or phosphate.
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  • 8
    ISSN: 1432-0827
    Keywords: Vitamin D ; Vitamin D deficiency ; Bone ; Pregnancy ; Lactation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effect of vitamin D on bone changes during the reproductive cycle in female rats has been investigated. One group of female rats was maintained on a vitamin D-deficient diet and another group on a vitamin D-replete diet from weaning. Both groups were mated with normal males and changes in their bones were determined histomorphometrically during pregnancy, lactation, and after weaning. All vitamin D-deficient rats had bone changes typical of rickets. Pregnancy caused significant reductions in mineralized tissue of trabecular and cortical bone in the vitamin D-deficient rats. Lactation caused further significant reductions in mineralized tissues of cortical and trabecular bone in both the vitamin D-deficient and vitamin D-replete animals, with the greatest changes seen at weaning. Some restoration of mineralized tissues occurred following weaning. There was an increase in tetracycline-labeled bone surface in the vitamin D-replete animals during lactation, likely due to an increase in bone formation rates. In the vitamin D-deficient animals during lactation, there was a decrease in tetracyclinelabeled bone surface, likely due to severely depressed bone mineralization. These results indicate that the mobilization of calcium from bone to maintain pregnancy and lactation occurs by a mechanism independent of vitamin D.
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  • 9
    ISSN: 1612-1112
    Keywords: Teflon capillary columns ; Chemically modified teflon ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of teflon capillary columns employing direct coating of the stationary phase to the chemically modified teflon surface and the role of the chemically modified teflon in the separation mechanism are described. Two types of contributions from the modified teflon have been observed: nonspecific adsorption of the carbon surface and specific interactions of polar groups in the carbon skeleton. The use of polar liquid phases can eliminate adsorption due to the presence of polar groups in the modified teflon.
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  • 10
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    Chromatographia 16 (1982), S. 60-62 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Amines ; Derivatization ; Chloroformate esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gas chromatographic analysis of amines after conversion to electron capture sensitive carbamates in two-phase systems has been studied. Hydrophilic compounds, for instance methylamine, are reacted with 2,2,2-trichloro-tert. butyl chloroformate. Quantitation below 10−7 M can be made by thermionic or electron capture detection. A hydrophobic amine, namely N,N-dimethyl-n-octylamine, was derivatized with 2,4,6-tribromophenyl chloroformate with addition of iodide ion to the aqueous phase. The favorable effect of iodide ion as well as the choice of pH and chloroformate ester is discussed.
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  • 11
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    Chromatographia 16 (1982), S. 98-102 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Rectangular channel ; Efficiency ; Capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic experiments have been performed in a truly rectangular channel with a 60∶1 cross-sectional aspect ratio, constructed according to the field-flow fractionation technology. It is shown that the peak broadening is controlled by the thickness of the channel while the maximum load is determined by the largest cross-sectional dimension. However, even with its elongated configuration, the side walls contribute significantly to the band broadening of solutes with a high diffusivity. Good agreement is found between the experimental plate height data and the recent theoretical calculations of Golay [13] taking into account the side-wall effect.
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  • 12
    ISSN: 1573-5036
    Keywords: Ammonification ; Cadmium ; Heavy metals ; Kinetics ; Lead ; Nitrification ; Perfusion incubations ; Polluted soils ; Selection ; Toxicity ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The sensitivity of the mineralization of nitrogen by a range of soils contaminated with heavy metals (up to 340 μg Cd g−1, 7500 μg Pb g−1 and 34000 μg Zn g−1) to the addition of heavy metals in solution were studied using pot incubations (ammonification) and a soil perfusion technique (nitrification). The ammonification of peptone showed little correlation between treatments with Cd, Zn (1000 and 5000 μg g−1) and Pb (10000 and 20000 μg g−1) and origin of the soil. Nitrification was considerably more sensitive to heavy metals than ammonification. All the soils had active, often large, populations of ammonifying and nitrifying organisms which showed substantial similarities between the soils. The rate of nitrifying activity (NO3−N production) was logrithmic in most cases. The presence of tolerant populations of nitrifying organisms in the contaminated soils was demonstrated. Tolerance was also eventually acquired after a longer lag phase, by the non-contaminated soil populations although the rate of activity was often reduced. Metals added in solution were adsorbed by the soil within 4 hours. Differences in toxicity between metal salts (chlorides, sulphates and acetate) were attributed to the amount left in solution. However, in many instances, acetate was found to stimulate all the stages in the mineralisation of nitrogen.
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  • 13
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    Hydrobiologia 91-92 (1982), S. 189-195 
    ISSN: 1573-5117
    Keywords: sediment ; rivers ; oxygen uptake ; continuous flow-through
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diurnal exchange of oxygen, over the sediment-water interface, was measured on ‘undisturbed’ sediment cores incubated on the river bank of three reaches in the river Susaa, Denmark. The incubation chambers were equipped with a double pumping system, driving an internal and an external flow, respectively. The internal flow created a unidirectional flow over the sediment surface, with the same velocity as the natural river flow. River water was continuously pumped through the incubation chambers (external flow). Magnetic valves alternately shifted the inlet and outlet water through a registration chamber equipped with an oxygen probe and a temperature transducer (A/D 540, integrated circuit). The potential was amplified and registered every minute on a tape recorder. The rate of exchange of oxygen in the chambers was described by the following equation: $${\text{r - exch(t) = }}\frac{{{\text{flow(t)}}}}{{{\text{volume}}}}{\text{[inlet(t) - outlet(t)] - }}\frac{{{\text{d[outlet(t)}}}}{{{\text{dt}}}}$$ Various methods for the numerical solution of the differential equation were used. Due to a small amount of ‘noise’ on the probes, the cubic spline method gave an unrealistically high variation in the oxygen uptake. A better description was obtained, when a Fourier transformation of the inlet and outlet concentrations of oxygen was made. When 15 Fourier coefficients were used, the r-value of the model was better than 0.996. On permanently dark sediment samples, a hysteresis effect between the oxygen exchange rate and the oxygen concentration and temperature appeared. The exchange rates were lower in periods with increasing oxygen concentration. A minimum in the exchange rate was obtained, before the minimum in the concentration of oxygen and temperature was found. This type of hysteresis could be explained by equilibration in connection with the transient state conditions. The hysteresis was probably enlarged by shifts in the size of the aerobic layer in the sediment. The importance of the hysteresis in oxygen balance models for rivers is discussed.
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  • 14
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    Hydrobiologia 91-92 (1982), S. 377-382 
    ISSN: 1573-5117
    Keywords: bioturbation ; oxygen ; sediment ; Lough Neagh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oxygen is transported 30 mm into the sediment at an 8 m depth site in eutrophic Lough Neagh by the irrigational activities of the benthic fauna. Faunal activity also mixes the upper 20 mm of sediment. Sediment oxygen uptake rate, redox potential-depth profile and the chlorophylla concentration were measured in the upper sediment layers from February to November 1979. Chlorophylla input to the sediment, following the Spring phytoplankton maximum, remained in the 0–1 cm sediment layer but did cause the redox potential profile to change from one with potentials around 400 mV in the upper 50 mm to one with a strong gradient over the 0–30 mm region. The start of benthic faunal activity in May caused the chlorophylla to be mixed into the 1–2 cm layer and also caused oxygen to be transported into the sediment at a rate sufficient to change the redox potential back to its initial state. The biodiffusion coefficient for solids in the upper 20 mm was estimated to be 6 × 10−8 cm2 s−1. Oxygen transport in the pore, waters of the upper sediment layers was considered to be best described as advection, caused by the irrigational activities of the benthic fauna.
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  • 15
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    Hydrobiologia 91-92 (1982), S. 491-500 
    ISSN: 1573-5117
    Keywords: phosphate ; sediment ; bioassay ; algae ; phosphate fractionation ; NTA extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The amount of phosphorus available to algae in the sediments of four lakes in the western part of the Netherlands has been assessed by means of chemical extraction and bioassay techniques. In addition to direct chemical sediment analyses, extractions were carried out with an NTA column method and a stepwise NH4 Cl-NaOH-HCI shaking method, the latter supposedly separating the weakly bound, the Fe- and Al-bound and the Ca-bound phosphates in the sediments. Bioassays, with sediment as the sole source of P, were made with Scenedesmus quadricauda in modified Skulberg's 28 medium to determine the amount of phosphates available to algae. The average total P concentration of the sediments varied from 0.8 to 3.6 mg P g−1 dry wt and correlated well with the net external P loading of the lakes. Uptake of P by algae in the bioassays varied from 0.4 to 36% — while NTA extracted 36–69% of the total P. The ratio NH4Cl extracted/ NaOH extracted/ HCI extracted phosphates is different from lake to lake, although in all lakes the highest extractions (27–62% of total P) are found in the NaOH fraction. However, in the peaty sediments of these lakes, the NaOH step extracted not only the Fe- and Al-bound phosphates but, also, large amounts of humus compounds. Hence, this fraction also contains non-available organic P. The results are related to soil type and chemical characteristics of the sediments, and compared with data from other authors. A positive correlation was found between phosphate available to algae and NTA- and NaOH-extractable P, but the correlation with total phosphorus was higher. Moreover, algal-extractable P proved to be positively correlated with total iron and clay content and negatively with the amount of organic matter. It is concluded that the sediments in the investigated lakes show great variability and that the chemical extraction techniques cannot replace the bioassays to assess the amount of phosphorus available to algae.
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  • 16
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    Hydrobiologia 91-92 (1982), S. 31-40 
    ISSN: 1573-5117
    Keywords: sediment ; entrainment ; deposition ; transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent work on the settling, diffusion, entrainment, and deposition of fine-grained sediments in fresh water is reviewed and synthesized. Particular attention is given to the dependence of these processes on sediment properties such as particle size. The application of this knowledge to the analysis and numerical modeling of sediment transport is also discussed. Much of the work is concerned with the Great Lakes and, more specifically, with the Western Basin of Lake Erie.
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  • 17
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    Hydrobiologia 91-92 (1982), S. 651-658 
    ISSN: 1573-5117
    Keywords: stream ; sediment ; sand ; hyporheal ; oxygen ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved oxygen, pH, conductivity and alkalinity of surface and subsurface interstitial waters were investigated at Mill Creek (a small, rural, predominantly sandy stream in east Texas). Dissolved oxygen concentration tended to decrease with sediment depth, while conductivity and alkalinity did not significantly change with substrate depth. Surface water pH was significantly higher than interstitial water (p = 0.05). Chemical analyses of subsurface water from a pre- to post-storm event showed a depression in dissolved oxygen concentration in moderate and deep interstitial waters, immediately following the return of stream base flow, with the deeper strata returning to pre-storm oxygen levels four days later. A thermal convective current mechanism is proposed which would serve to transport surface water downward into these deeper interstices.
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  • 18
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    Hydrobiologia 91-92 (1982), S. 491-500 
    ISSN: 1573-5117
    Keywords: phosphate ; sediment ; bioassay ; algae ; phosphate fractionation ; NTA extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The amount of phosphorus available to algae in the sediments of four lakes in the western part of the Netherlands has been assessed by means of chemical extraction and bioassay techniques. In addition to direct chemical sediment analyses, extractions were carried out with an NTA column method and a stepwise NH4 Cl-NaOH-HCI shaking method, the latter supposedly separating the weakly bound, the Fe- and Al-bound and the Ca-bound phosphates in the sediments. Bioassays, with sediment as the sole source of P, were made withScenedesmus quadricauda in modified Skulberg's 28 medium to determine the amount of phosphates available to algae. The average total P concentration of the sediments varied from 0.8 to 3.6 mg P g−1 dry wt and correlated well with the net external P loading of the lakes. Uptake of P by algae in the bioassays varied from 0.4 to 36% — while NTA extracted 36–69% of the total P. The ratio NH4Cl extracted/ NaOH extracted/ HCI extracted phosphates is different from lake to lake, although in all lakes the highest extractions (27–62% of total P) are found in the NaOH fraction. However, in the peaty sediments of these lakes, the NaOH step extracted not only the Fe- and Al-bound phosphates but, also, large amounts of humus compounds. Hence, this fraction also contains non-available organic P. The results are related to soil type and chemical characteristics of the sediments, and compared with data from other authors. A positive correlation was found between phosphate available to algae and NTA- and NaOH-extractable P, but the correlation with total phosphorus was higher. Moreover, algal-extractable P proved to be positively correlated with total iron and clay content and negatively with the amount of organic matter. It is concluded that the sediments in the investigated lakes show great variability and that the chemical extraction techniques cannot replace the bioassays to assess the amount of phosphorus available to algae.
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  • 19
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    Hydrobiologia 86 (1982), S. 99-103 
    ISSN: 1573-5117
    Keywords: diatoms ; lakes ; land use ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data on recenr diatom community structure and relevant environmental characteristics from the lakes and their catchments have been collected from 151 oligotrophic lakes in eastern Finland. The pattern of frequency distribution of diatoms as a function of environmental variables, including land use in the catchment, differs between diatom taxa and indicates the optimum conditions and amplitude of occurrence for particular species. This kind of study should lead to increased understanding of the environmental requirements of diatom species and will be useful in the interpretation of historical changes in lakes as well as in forecasting possible future changes.
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  • 20
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    Hydrobiologia 91-92 (1982), S. 377-382 
    ISSN: 1573-5117
    Keywords: bioturbation ; oxygen ; sediment ; Lough Neagh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oxygen is transported 30 mm into the sediment at an 8 m depth site in eutrophic Lough Neagh by the irrigational activities of the benthic fauna. Faunal activity also mixes the upper 20 mm of sediment. Sediment oxygen uptake rate, redox potential-depth profile and the chlorophylla concentration were measured in the upper sediment layers from February to November 1979. Chlorophylla input to the sediment, following the Spring phytoplankton maximum, remained in the 0–1 cm sediment layer but did cause the redox potential profile to change from one with potentials around 400 mV in the upper 50 mm to one with a strong gradient over the 0–30 mm region. The start of benthic faunal activity in May caused the chlorophylla to be mixed into the 1–2 cm layer and also caused oxygen to be transported into the sediment at a rate sufficient to change the redox potential back to its initial state. The biodiffusion coefficient for solids in the upper 20 mm was estimated to be 6 × 10−8 cm2 s−1. Oxygen transport in the pore, waters of the upper sediment layers was considered to be best described as advection, caused by the irrigational activities of the benthic fauna.
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  • 21
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    Hydrobiologia 91-92 (1982), S. 415-429 
    ISSN: 1573-5117
    Keywords: phosphorus release ; sediment ; nitrate ; redox-potential ; sorption ; fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphorus release from surface sediments of eight lakes, mainly shallow lakes in agricultural areas, was studied in laboratory batch experiments with additions of acetate and/ or nitrate. The lake sediments could be separated into three categories. Some sediments did not release phosphorus under any conditions. The second category showed a high phosphorus release rate when acetate was added, in order to stimulate bacterial activity and oxygen consumption. The addition of nitrate, only, stabilized the redox conditions and prevented phosphorus release. This pattern followed the classical theories of Einsele and Mortimer. The third sediment category released phosphorus up to some level which remained constant throughout the experiment, and was independent of acetate and/or nitrate additions. Several extraction procedures and adsorption-desorption experiments were performed in order to characterize the sediment phosphorus and thus explain the different behaviours of the three sediment categories.
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  • 22
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    Hydrobiologia 91-92 (1982), S. 285-292 
    ISSN: 1573-5117
    Keywords: PAH ; aliphatic hydrocarbons ; sediment ; stormwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The top and bottom of two sediment cores collected from an urban receiving basin in NW London, and stormwater samples from the attendant catchment, have been analysed for their hydrocarbon content. In surface sediments, basal sediments and stormwater, total aliphatic hydrocarbon levels are 445–690 µg g−1 dry wt., 43–224 µg g−1 and 0.36–1.10 mg l−1, respectively; and total levels of polyaromatic hydrocarbons (PAHs) are 780–1 100 µg g−1, 310–640 µg g1 and 5.83–18.21 mg l−1, respectively. Biodegradation of aliphatics is assessed by phytane:n-C18 and pristane: n-C17 ratios. Hydrocarbon sources are determined from phytane: pristane ratios, odd: even carbon chain length ratios, the presence of an unresolved complex mixture, and by comparison of the amount of methyl-substituted PAH s with that of the parent compounds. Comparison of total levels between surface and basal sediments shows a 1 to 3 fold increase in total PAHs and a 3 to 10 fold increase in aliphatic hydrocarbons over a 120 year period.
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  • 23
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    Hydrobiologia 91-92 (1982), S. 41-57 
    ISSN: 1573-5117
    Keywords: biogeochemistry ; rivers ; sediment ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To understand the nature of sediment-associated nutrient and contaminant transport dynamics in fluvial systems, a stormflow sampling program of suspended solids is reported for one water year in a representative rural diffuse source catchment of southeastern Ontario. Bulk samples of subsieve suspended solids were obtained using field-portable continuous-flow centrifuge apparatus. The physical and geochemical properties of suspended solids show no significant intersite differences over reaches of 1 500–2 000 m, yet display distinctive seasonal trends. Systematic seasonal changes in particle size, organic content, and Ca, P, Mn, Al, Ti, Fe, and K appear to reflect the changing role of partial area hydrology. Ca, P, and Mn are bioaccumulated by stream algae. Mineral signature is relatively constant over the year.
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    Hydrobiologia 96 (1982), S. 177-184 
    ISSN: 1573-5117
    Keywords: sediment ; reservoir ; stream ; macroinvertebrates
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    Topics: Biology
    Notes: Abstract Effects of sediment release from Guernsey Reservoir on macroinvertebrates of the North Platte River, Wyoming, were investigated during summer 1981. Suspended solids concentrations during sediment release increased from 〈20 mg l−1 to 〉300 mg l−1. Because fine particulates remained in suspension, mean particle size of substrates was unaltered. Densities of chironomids decreased 90% + during sediment release but recovered to initial levels in 3 weeks after the release ended. Densities of mayflies and oligochaetes increased. Changes in benthic populations were highly correlated with increases in suspended solids.
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  • 25
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    Hydrobiologia 91-92 (1982), S. 415-429 
    ISSN: 1573-5117
    Keywords: phosphorus release ; sediment ; nitrate ; redox-potential ; sorption ; fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphorus release from surface sediments of eight lakes, mainly shallow lakes in agricultural areas, was studied in laboratory batch experiments with additions of acetate and/ or nitrate. The lake sediments could be separated into three categories. Some sediments did not release phosphorus under any conditions. The second category showed a high phosphorus release rate when acetate was added, in order to stimulate bacterial activity and oxygen consumption. The addition of nitrate, only, stabilized the redox conditions and prevented phosphorus release. This pattern followed the classical theories of Einsele and Mortimer. The third sediment category released phosphorus up to some level which remained constant throughout the experiment, and was independent of acetate and/or nitrate additions. Several extraction procedures and adsorption-desorption experiments were performed in order to characterize the sediment phosphorus and thus explain the different behaviours of the three sediment categories.
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    Hydrobiologia 91-92 (1982), S. 651-658 
    ISSN: 1573-5117
    Keywords: stream ; sediment ; sand ; hyporheal ; oxygen ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved oxygen, pH, conductivity and alkalinity of surface and subsurface interstitial waters were investigated at Mill Creek (a small, rural, predominantly sandy stream in east Texas). Dissolved oxygen concentration tended to decrease with sediment depth, while conductivity and alkalinity did not significantly change with substrate depth. Surface water pH was significantly higher than interstitial water (p = 0.05). Chemical analyses of subsurface water from a pre- to post-storm event showed a depression in dissolved oxygen concentration in moderate and deep interstitial waters, immediately following the return of stream base flow, with the deeper strata returning to pre-storm oxygen levels four days later. A thermal convective current mechanism is proposed which would serve to transport surface water downward into these deeper interstices.
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  • 27
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    Hydrobiologia 91-92 (1982), S. 491-500 
    ISSN: 1573-5117
    Keywords: phosphate ; sediment ; bioassay ; algae ; phosphate fractionation ; NTA extraction
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    Topics: Biology
    Notes: Abstract The amount of phosphorus available to algae in the sediments of four lakes in the western part of the Netherlands has been assessed by means of chemical extraction and bioassay techniques. In addition to direct chemical sediment analyses, extractions were carried out with an NTA column method and a stepwise NH4 Cl-NaOH-HCI shaking method, the latter supposedly separating the weakly bound, the Fe- and Al-bound and the Ca-bound phosphates in the sediments. Bioassays, with sediment as the sole source of P, were made withScenedesmus quadricauda in modified Skulberg's 28 medium to determine the amount of phosphates available to algae. The average total P concentration of the sediments varied from 0.8 to 3.6 mg P g−1 dry wt and correlated well with the net external P loading of the lakes. Uptake of P by algae in the bioassays varied from 0.4 to 36% — while NTA extracted 36–69% of the total P. The ratio NH4Cl extracted/ NaOH extracted/ HCI extracted phosphates is different from lake to lake, although in all lakes the highest extractions (27–62% of total P) are found in the NaOH fraction. However, in the peaty sediments of these lakes, the NaOH step extracted not only the Fe- and Al-bound phosphates but, also, large amounts of humus compounds. Hence, this fraction also contains non-available organic P. The results are related to soil type and chemical characteristics of the sediments, and compared with data from other authors. A positive correlation was found between phosphate available to algae and NTA- and NaOH-extractable P, but the correlation with total phosphorus was higher. Moreover, algal-extractable P proved to be positively correlated with total iron and clay content and negatively with the amount of organic matter. It is concluded that the sediments in the investigated lakes show great variability and that the chemical extraction techniques cannot replace the bioassays to assess the amount of phosphorus available to algae.
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  • 28
    ISSN: 1573-5117
    Keywords: bioturbation ; modelling ; sediment ; phosphorus ; Chironomus anthracinus ; Potamothrix hammoniensis
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    Topics: Biology
    Notes: Abstract A multilayer sediment-water exchange model was used to evaluate the importance of bioturbation in the profundal sediments of L. Esrom. The temporal variation of the vertical distribution of sedimentary phosphorus fractions was modelled with an objective function of 1.50. Deviations between measured and simulated values occurred in the spring, where the measured pool of sedimentary phosphorus sharply declined in the surface sediments. The application of a model for the activity ofChironomus anthracinus based on biomass, oxygen consumption and temperature improved the model in the spring period. The downwards transport of easy-degradable surface sediments reduced the average release of sedimentary phosphorus from 12 mg P · m−2 · day−1 to 11 mg P · M−2 · day−1. The introduction of a similar model for the other important burrowing species in L. Esrom,Potamothrix hammoniensis, lowered the objective function to 1.37 and increased the average release to 12.5 mg P · m−2 · day−1. The minor role of bioturbation in sediment processes is discussed.
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  • 29
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    Hydrobiologia 91-92 (1982), S. 285-292 
    ISSN: 1573-5117
    Keywords: PAH ; aliphatic hydrocarbons ; sediment ; stormwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The top and bottom of two sediment cores collected from an urban receiving basin in NW London, and stormwater samples from the attendant catchment, have been analysed for their hydrocarbon content. In surface sediments, basal sediments and stormwater, total aliphatic hydrocarbon levels are 445–690 µg g−1 dry wt., 43–224 µg g−1 and 0.36–1.10 mg l−1, respectively; and total levels of polyaromatic hydrocarbons (PAHs) are 780–1 100 µg g−1, 310–640 µg g1 and 5.83–18.21 mg l−1, respectively. Biodegradation of aliphatics is assessed by phytane:n-C18 and pristane: n-C17 ratios. Hydrocarbon sources are determined from phytane: pristane ratios, odd: even carbon chain length ratios, the presence of an unresolved complex mixture, and by comparison of the amount of methyl-substituted PAH s with that of the parent compounds. Comparison of total levels between surface and basal sediments shows a 1 to 3 fold increase in total PAHs and a 3 to 10 fold increase in aliphatic hydrocarbons over a 120 year period.
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    Hydrobiologia 91-92 (1982), S. 41-57 
    ISSN: 1573-5117
    Keywords: biogeochemistry ; rivers ; sediment ; water quality
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    Topics: Biology
    Notes: Abstract To understand the nature of sediment-associated nutrient and contaminant transport dynamics in fluvial systems, a stormflow sampling program of suspended solids is reported for one water year in a representative rural diffuse source catchment of southeastern Ontario. Bulk samples of subsieve suspended solids were obtained using field-portable continuous-flow centrifuge apparatus. The physical and geochemical properties of suspended solids show no significant intersite differences over reaches of 1 500–2 000 m, yet display distinctive seasonal trends. Systematic seasonal changes in particle size, organic content, and Ca, P, Mn, Al, Ti, Fe, and K appear to reflect the changing role of partial area hydrology. Ca, P, and Mn are bioaccumulated by stream algae. Mineral signature is relatively constant over the year.
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  • 31
    ISSN: 1573-5117
    Keywords: bioturbation ; modelling ; sediment ; phosphorus ; Chironomus anthracinus ; Potamothrix hammoniensis
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    Topics: Biology
    Notes: Abstract A multilayer sediment-water exchange model was used to evaluate the importance of bioturbation in the profundal sediments of L. Esrom. The temporal variation of the vertical distribution of sedimentary phosphorus fractions was modelled with an objective function of 1.50. Deviations between measured and simulated values occurred in the spring, where the measured pool of sedimentary phosphorus sharply declined in the surface sediments. The application of a model for the activity ofChironomus anthracinus based on biomass, oxygen consumption and temperature improved the model in the spring period. The downwards transport of easy-degradable surface sediments reduced the average release of sedimentary phosphorus from 12 mg P · m−2 · day−1 to 11 mg P · M−2 · day−1. The introduction of a similar model for the other important burrowing species in L. Esrom,Potamothrix hammoniensis, lowered the objective function to 1.37 and increased the average release to 12.5 mg P · m−2 · day−1. The minor role of bioturbation in sediment processes is discussed.
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    Hydrobiologia 86 (1982), S. 105-108 
    ISSN: 1573-5117
    Keywords: convection ; sediment ; temperature ; convectional diffusion ; material exchange
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    Topics: Biology
    Notes: Abstract In two Finnish lakes, in winter and summer, a constant temperature in the sediment was not reached until a depth of 1.5–2 m. The thermal stratification pattern in the sediment was similar to that in water. However, the lack of turbulent mixing in the sediment resulted in a thin ‘episediment’. This stratification was caused by convection. Convection currents in the sediment were most prevalent during spring and autumn overturn when the density of overlying water was greater than that of the interstitial water. Convection was also possible in winter. The duration and magnitude of convection was dependent on warming and cooling rates. Such convection currents may be important in material exchange between sediment and water since material concentrations in interstitial water are 5–100 times greater than in overlying water.
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  • 33
    ISSN: 1573-5117
    Keywords: Hexagenia ; sediment ; sulfur ; nitrogen ; bioturbation
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    Topics: Biology
    Notes: Abstract Effects of the burrowing mayfly, Hexagenia, on nitrogen and sulfur fractions of sediment, and overlying water were determined. Laboratory microcosms were used to reproduce the benthic environment. The activities of Hexagenia increased sediment Eh (1.98 ± 0.486 (22) mV · day −1), and decreased pH in sediment (−0.007 ± 0.001 (22) day −1) and overlying water(-0.024 ± 0.004 (10) day−1). In the control, Eh decreased and pH did not change. The presence of Hexagenia also markedly increased ammonia in sediment (5.46 ± 0.14 (22) ppm N · day−1) and overlying water (0.792 ± 0.154 (10) ppm N · day−1), while the control did not change. In addition, the sulfate fraction of sediment (0.177 ± 0.006 (17)% dry mass) and water (50.0 ± 4.9 (5) mg · I−1) in microcosms with Hexagenia was greater than that of the control (0.151 ± 0.005 (16)% dry mass; 14.7 ± 1.71 (3) mg · 1−1) at the termination of the experiment. Hexagenia may also stimulate the mineralization of carbon-bonded sulfur. The general role of Hexagenia in altering sediment chemistry is discussed.
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    Hydrobiologia 91-92 (1982), S. 377-382 
    ISSN: 1573-5117
    Keywords: bioturbation ; oxygen ; sediment ; Lough Neagh
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    Topics: Biology
    Notes: Abstract Oxygen is transported 30 mm into the sediment at an 8 m depth site in eutrophic Lough Neagh by the irrigational activities of the benthic fauna. Faunal activity also mixes the upper 20 mm of sediment. Sediment oxygen uptake rate, redox potential-depth profile and the chlorophyll a concentration were measured in the upper sediment layers from February to November 1979. Chlorophyll a input to the sediment, following the Spring phytoplankton maximum, remained in the 0–1 cm sediment layer but did cause the redox potential profile to change from one with potentials around 400 mV in the upper 50 mm to one with a strong gradient over the 0–30 mm region. The start of benthic faunal activity in May caused the chlorophyll a to be mixed into the 1–2 cm layer and also caused oxygen to be transported into the sediment at a rate sufficient to change the redox potential back to its initial state. The biodiffusion coefficient for solids in the upper 20 mm was estimated to be 6 × 10−8 cm2 s−1. Oxygen transport in the pore, waters of the upper sediment layers was considered to be best described as advection, caused by the irrigational activities of the benthic fauna.
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    Hydrobiologia 91-92 (1982), S. 269-284 
    ISSN: 1573-5117
    Keywords: heavy metals ; sediment ; concentrates ; extraction ; availability
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    Topics: Biology
    Notes: Abstract Data from mechanical concentrates of recent sediments indicate that clay minerals, clay-rich aggregates and heavy minerals are the major carriers of heavy metals in detrital sediment fractions. Hydrous Fe/Mn oxides and carbonates and sulfides, in their specific environments, are the predominant accumulative phases for heavy metals in autochthonous fractions. Sequential chemical extraction techniques permit the estimation of characteristic heavy metal bonding forms: exchangeable metal cations, easily reducible, moderately reducible, organic and residual metal fractions, whereby both diagenetic processes and the potential availability of toxic compounds can be studied. The data from lakes affected by acid precipitation indicate that zinc, cobalt and nickel are mainly released from the easily reducible sediment fractions and cadmium from organic phases. In contrast at pH 4.4, neither lead nor copper seem to be remobilized to any significant extent. Immobilization by carbonate precipitation seems to provide an effective mechanism for the reduction of dissolved inputs 9f metals such as zinc and cadmium in pH-buffered, hard water systems.
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    Hydrobiologia 91-92 (1982), S. 651-658 
    ISSN: 1573-5117
    Keywords: stream ; sediment ; sand ; hyporheal ; oxygen ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved oxygen, pH, conductivity and alkalinity of surface and subsurface interstitial waters were investigated at Mill Creek (a small, rural, predominantly sandy stream in east Texas). Dissolved oxygen concentration tended to decrease with sediment depth, while conductivity and alkalinity did not significantly change with substrate depth. Surface water pH was significantly higher than interstitial water (p = 0.05). Chemical analyses of subsurface water from a pre- to post-storm event showed a depression in dissolved oxygen concentration in moderate and deep interstitial waters, immediately following the return of stream base flow, with the deeper strata returning to pre-storm oxygen levels four days later. A thermal convective current mechanism is proposed which would serve to transport surface water downward into these deeper interstices.
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    Hydrobiologia 91-92 (1982), S. 31-40 
    ISSN: 1573-5117
    Keywords: sediment ; entrainment ; deposition ; transport
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    Topics: Biology
    Notes: Abstract Recent work on the settling, diffusion, entrainment, and deposition of fine-grained sediments in fresh water is reviewed and synthesized. Particular attention is given to the dependence of these processes on sediment properties such as particle size. The application of this knowledge to the analysis and numerical modeling of sediment transport is also discussed. Much of the work is concerned with the Great Lakes and, more specifically, with the Western Basin of Lake Erie.
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    Hydrobiologia 91-92 (1982), S. 189-195 
    ISSN: 1573-5117
    Keywords: sediment ; rivers ; oxygen uptake ; continuous flow-through
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    Topics: Biology
    Notes: Abstract The diurnal exchange of oxygen, over the sediment-water interface, was measured on ‘undisturbed’ sediment cores incubated on the river bank of three reaches in the river Susaa, Denmark. The incubation chambers were equipped with a double pumping system, driving an internal and an external flow, respectively. The internal flow created a unidirectional flow over the sediment surface, with the same velocity as the natural river flow. River water was continuously pumped through the incubation chambers (external flow). Magnetic valves alternately shifted the inlet and outlet water through a registration chamber equipped with an oxygen probe and a temperature transducer (A/D 540, integrated circuit). The potential was amplified and registered every minute on a tape recorder. The rate of exchange of oxygen in the chambers was described by the following equation: $${\text{r - exch(t) = }}\frac{{{\text{flow(t)}}}}{{{\text{volume}}}}{\text{[inlet(t) - outlet(t)] - }}\frac{{{\text{d[outlet(t)}}}}{{{\text{dt}}}}$$ Various methods for the numerical solution of the differential equation were used. Due to a small amount of ‘noise’ on the probes, the cubic spline method gave an unrealistically high variation in the oxygen uptake. A better description was obtained, when a Fourier transformation of the inlet and outlet concentrations of oxygen was made. When 15 Fourier coefficients were used, the r-value of the model was better than 0.996. On permanently dark sediment samples, a hysteresis effect between the oxygen exchange rate and the oxygen concentration and temperature appeared. The exchange rates were lower in periods with increasing oxygen concentration. A minimum in the exchange rate was obtained, before the minimum in the concentration of oxygen and temperature was found. This type of hysteresis could be explained by equilibration in connection with the transient state conditions. The hysteresis was probably enlarged by shifts in the size of the aerobic layer in the sediment. The importance of the hysteresis in oxygen balance models for rivers is discussed.
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  • 39
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    Hydrobiologia 91-92 (1982), S. 269-284 
    ISSN: 1573-5117
    Keywords: heavy metals ; sediment ; concentrates ; extraction ; availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data from mechanical concentrates of recent sediments indicate that clay minerals, clay-rich aggregates and heavy minerals are the major carriers of heavy metals in detrital sediment fractions. Hydrous Fe/Mn oxides and carbonates and sulfides, in their specific environments, are the predominant accumulative phases for heavy metals in autochthonous fractions. Sequential chemical extraction techniques permit the estimation of characteristic heavy metal bonding forms: exchangeable metal cations, easily reducible, moderately reducible, organic and residual metal fractions, whereby both diagenetic processes and the potential availability of toxic compounds can be studied. The data from lakes affected by acid precipitation indicate that zinc, cobalt and nickel are mainly released from the easily reducible sediment fractions and cadmium from organic phases. In contrast at pH 4.4, neither lead nor copper seem to be remobilized to any significant extent. Immobilization by carbonate precipitation seems to provide an effective mechanism for the reduction of dissolved inputs 9f metals such as zinc and cadmium in pH-buffered, hard water systems.
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    Hydrobiologia 91-92 (1982), S. 415-429 
    ISSN: 1573-5117
    Keywords: phosphorus release ; sediment ; nitrate ; redox-potential ; sorption ; fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphorus release from surface sediments of eight lakes, mainly shallow lakes in agricultural areas, was studied in laboratory batch experiments with additions of acetate and/ or nitrate. The lake sediments could be separated into three categories. Some sediments did not release phosphorus under any conditions. The second category showed a high phosphorus release rate when acetate was added, in order to stimulate bacterial activity and oxygen consumption. The addition of nitrate, only, stabilized the redox conditions and prevented phosphorus release. This pattern followed the classical theories of Einsele and Mortimer. The third sediment category released phosphorus up to some level which remained constant throughout the experiment, and was independent of acetate and/or nitrate additions. Several extraction procedures and adsorption-desorption experiments were performed in order to characterize the sediment phosphorus and thus explain the different behaviours of the three sediment categories.
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    Hydrobiologia 95 (1982), S. 79-114 
    ISSN: 1573-5117
    Keywords: periphyton ; submerged macrophytes ; sediment ; artificial substrates ; oxygen exchange ; production ; decomposition ; sedimentation
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    Topics: Biology
    Notes: Abstract Epiphyton and epipelon were quantitatively collected, respectively, from the submerged macrophytes and the sandy lake bottom of Lake Vechten (The Netherlands). On a weight basis, epiphyton was maximal in autumn and epipelon in summer. In winter the chemical composition of epiphyton and epipelon was similar. In summer the epiphyton had on a unit weight basis more organic matter and carbonate, and had per unit organic matter a higher algal number, nitrogen and energy content than the epipelon. Algae predominating the epiphyton were filamentous greens and pennate diatoms; those in the epipelon were pennate diatoms and blue-green algae. In both cases, species known to frequent the phytoplankton were abundant. The diatoms were quantified using paper chromatographic pigment analyses. Both the epiphyton and the epipelon exhibited maximal photosynthesis in mid summer. That light was generally the limiting factor was evident from periphyton developed on artificial substrates. This periphyton differed widely in its composition from that on the natural substrates, mainly because the latter collected much more sedimenting matter. In dense Ceratophyllum stands light was severely attenuated and the significant gradients in oxygen and pH were caused by the differences with depth in the proportions of photosynthesis and respiration. The oxygen content and pH at the bottom decreased owing to epipelic respiration. The epiphytic composition depended greatly on the degree of light attenuation. The epiphytic and epipelic respiration, except during part of the early summer, exceeded photosynthesis on a 24 h basis; this included the macrophytic photosynthesis during the time the vegetation was maximally developed. During the growing season import of organic matter, i.e. deposited seston, greatly exceeded that due to the photosynthetic production. After the summer maximum, the epipelon decreased faster than predicted from its oxygen exchange. It was concluded that sedimentation and resuspension determined mainly the changes in epiphyton and epipelon. Especially when covered with vegetation, the lower littoral of Lake Vechten plays a large part in the aerobic decomposition of sestonic organic matter.
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    Chromatographia 15 (1982), S. 704-706 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Isopropyliden-sorboses ; TMS-derivatives ; GC-MS combined technique ; Mass spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed using gas chromatography — electron impact mass spectrometry for the determination of the di-0-isopropylidene-sorbofuranose and mono-0-isopropylidene-sorbofuranose. The compounds are separated as their trimethylsilyl derivatives on a capillary column coated with the stationary phase SE-52. The mass spectra show that the silylation reaction is quantitiative and that the isopropylidene groups does not change.
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    Chromatographia 15 (1982), S. 183-185 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Analysis of ethylbenzene hydroperoxide ; Time normalization method
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    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method, based on the time normalization technique, is described for the analysis of ethylbenzene hydroperoxide in mixtures containing ethylbenzene, acetophenone, 1-phenylethanol, benzaldehyde and phenol. Different liquid phases were tested and the best results were obtained with tricresyl phosphate and neopentyl glycol sebacate. The influence of the support, the liquid loading and the gas velocity are discussed.
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    Chromatographia 15 (1982), S. 625-630 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open-tubular (capillary) columns ; Comparison of liquid phases ; Influence of temperature ; Retention index data
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    Topics: Chemistry and Pharmacology
    Notes: Summary The influence of temperature and liquid phase film thickness of open-tubular (capillary) columns on the retention index values of hydrocarbons on methylsilicone liquid phases is discussed. Data obtained on methylsilicones and squalane are compared. Retention index values of 43 hydrocarbons between 40 and 70 °C on OV-101 liquid phase are listed.
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    Chromatographia 15 (1982), S. 351-354 
    ISSN: 1612-1112
    Keywords: Supported catalysts ; Reserved-flow GC ; Drying step ; Gas chromatography
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    Topics: Chemistry and Pharmacology
    Notes: Summary Application of reversed-flow gas chromatography to study the drying step in the preparation of supported catalysts is proposed. It is demonstrated that this technique can be applied to investigate the kinetic law followed, as well as to obtain kinetic parameters of drying (rate constants, activation energies and frequency factors). Amaterial illustrating this application is γ-Al2O3 impregnated with usual organic solvents (n-C5H12,n-C6H14,n-C7H16, CH3COCH3 and CH3CH2OH). It was found that in all cases above a simple first-order law based onone kind of active site is followed. Moreover, it was observed that the activation energyE a of the drying process increases almost linearly with the relative molecular mass of the solvent, whereas for the same solventE a increases with the amount used. The operation of a kinetic compensation effect suggests “similar” activated complexes of the various solvents used.
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  • 46
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fused silica capillaries ; New polar phases: OV-1701 and RSL-310 ; Immobilization
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    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities of OV-1701 and RSL-310, two new stationary phases, have been evaluated for capillary gas chromatography in fused silica columns. OV-1701 is a cyanopropylphenyldimethyl polysiloxane of moderate polarity possessing excellent chromatographic characteristics. The phase exhibits high coating and chromatographic efficiencies, high temperature stability and is suitable for cross-linking. RSL-310 is a polar liquid stationary phase yet to be permanently bonded in a capillary column. The selectivity of both phases extends the applicability of fused silica columns.
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    Chromatographia 15 (1982), S. 241-244 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Monosaccharides ; Polyols ; GC of TMS derivatives
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    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes the gas chromatographic separation of the mixture of isopropylidene monosaccharides, and their trimethylsilyl derivatives. Based on the total analysis time and resolution the best stationary phase was SF-96 using Chromosorb G as the solid support and temperature programming.
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    Chromatographia 15 (1982), S. 312-314 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Injection-port modification ; Oxygen and nitrogen traces
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    Topics: Chemistry and Pharmacology
    Notes: Summary The paper presents a new device modifying normal injection port of a gas chromatograph for eliminating air contamination thus enabling determination of traces of oxygen or nitrogen. Further modification is also proposed which enables the analysis to be carried out with a limited quantity of sample gas. Potential application of this device in the analysis of reactive gases like florine has been indicated.
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  • 49
    ISSN: 1612-1112
    Keywords: Phthalides ; Gas chromatography ; Chromosorb W ; Isomerization ; Ligustilide
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    Topics: Chemistry and Pharmacology
    Notes: Summary During GLC of naturally occurring mixtures of phthalides on packed columns an artefact was sometimes detected that originated from Z-ligustilide. Active sites of Chromosorb W were responsible for the formation of the artefact, that was assumed to be E-ligustilide as GC-MS revealed that its mass spectrum was identical with that of Z-ligustilide. No isomerization was observed when freshly coated Chromosorb W was used or the support was deactivated by benzoyl chloride or melamine. The identity of the artefact was confirmed by UV irradiation experiments.
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  • 50
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    Chromatographia 15 (1982), S. 30-32 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Arsenic ; Inorganic materials
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    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the quantitative chlorination and extraction of arsenic as arsenic trichloride from a number of alloys. The conditions for the quantitative gas chromatographic measurement of the volatile chloride have been studied. The proposed method for inorganic materials is very fast giving results within 10 min; sensitive, 1.5·10−13 g As can be detected, simple and accurate. At the ng level of As the error is about 20% with a standard deviation less than 20%, and at the 10pg level the error is about 36% with a standard deviation of 44%.
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  • 51
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    Chromatographia 15 (1982), S. 765-768 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Preparative scale chromatography ; Capacity ; Dual-stage separation
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    Topics: Chemistry and Pharmacology
    Notes: Summary The capacity of different versions of single- and dual-stage separation of mixtures on a preparative scale is considered. It has been shown that dual-stage separation with intermediate condensation considerably enhances the capacity of the installation as compared with a single-stage process.
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  • 52
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    Chromatographia 15 (1982), S. 117-124 
    ISSN: 1612-1112
    Keywords: Various packed GC column ; Gas chromatography ; Porous layer beads ; GC/MS analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary Theoretical comparisons of various packed GC column types are presented with respect to analysis time, efficiency, sample dilution, and sample capacity for a given maximum inlet pressure. In particular, totally porous particles, porous layer beads, and glass beads are compared with one another. It is shown that 30 μm porous layer beads offer a useful compromise between analysis time and plate count with relatively good sample capacity. Moreover, when using 1 mm i.d. columns (microbore), outlet flow rates that are reasonable for direct coupling to magnetic sector mass spectrometers are achieved making these columns suitable for GC/MS. Using 30 μm Zipax porous layer beads, columns yielding 8,000 to 10,000 plates/meter have been produced with inlet pressures of 13 to 26 atm. A simple modification of the injection port converts the maximum inlet pressure of a commercial gas chromatograph to 26 atm. With such pressures, columns in excess of 20,000 plates can be achieved. Chromatograms are presented illustrating the promise of these microbore columns for GC and GC/MS analysis.
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  • 53
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    Chromatographia 15 (1982), S. 245-248 
    ISSN: 1612-1112
    Keywords: Chromatoscopy ; Gas chromatography ; Graphitized carbon black ; Molecular structure and retention ; Aromatic hydrocarbons
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    Topics: Chemistry and Pharmacology
    Notes: Summary A molecular-statistical calculation of the retention volumes at zero sample size on graphitized thermal carbon black is carried out for quasi-rigid molecules of fluorene, indene, 1-methylindene, 2-methylindene and three dimethylindenes. A reasonable agreement is observed between the calculated and the available experimental gas chromatographic data. The potential barrier to internal rotation and the torsional angle in styrene molecules are estimated by comparing theoretically calculated and measured retention volumes.
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  • 54
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silicone liquid phases ; Oxidation
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    Topics: Chemistry and Pharmacology
    Notes: Summary The on-column oxidation of apolar and polar silicones used as gas chromatographic stationary phases is investigated. Even at 225° the effects of oxidation are found to be slight. Of the materials investigated the methylphenylsilicones are the most stable.
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  • 55
    ISSN: 1612-1112
    Keywords: Glass capillary ; Gas chromatography ; Methyl chloroacetates ; Methyl chloropropanoates ; Methyl chlorobutanoates
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    Topics: Chemistry and Pharmacology
    Notes: Summary The gas chromatography of all chlorinated methyl acetates, methyl propanoates and methyl mono- and dichlorobutanoates has been studied on Carbowax 20M and SE-30 glass capillary columns under various running conditions. The order of elution on a non-polar column was largely determined by the boiling point of esters, whereas on a polar column it was much influenced by the structure of compounds. Complete separation of the combined mixture of all 27 compounds could not be achieved, however, methyl 3,3-dichlorobutanoate was the only ester overlapped on both columns in spite of the various column temperatures used. The best separation of the mixture was on Carbowax 20M with a temperature program from 50°C at 8°C/min, isothermal running conditions leading either to poor separation of volatile components or long analysis time and broad peaks of higher chlorinated esters. The relative retention times for compounds at the various column temperatures are given and the retention order on a polar and on a non-polar column discussed.
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  • 56
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    Chromatographia 15 (1982), S. 517-520 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Carbon-silica adsorbents ; n-Octadecanol film ; Phase transitions
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    Topics: Chemistry and Pharmacology
    Notes: Summary The properties of the n-octadecanol film on carbon-silica adsorbent (Carbosil) were investigated. It was found that n-octadecanol forms an oriented film on the Carbosil's surface. If the surface of the basic silica gel is not completely covered with carbon, then the phase transition takes place in this film at a temperature higher than the melting temperature of n-octadecanol. One may distinguish two forms of this film, characterised by the different structures and the temperatures of the phase transitions. The first exists on the surface of silica gel unblocked by carbon. This part of the film is a monolayer, in which the alcohol molecules are vertically oriented. The solid compact-liquid expanded type phase transition at the well-defined temperature occurs in this film. In the second part of the film formed on the carbon surface, there is a multilayer of n-octadecanol. Its molecules are probably parallely oriented in relationship to the adsorbent surface. This film desintegrates progressively when the temperature increase. Maximum temperature of this phase transition is lower than the temperature of its analogue on pure silica gel surface.
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  • 57
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    Chromatographia 15 (1982), S. 546-558 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Quantitative analysis ; Sample inlet systems ; High-speed analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary The attainment of precise quatitative analytical data using open-tubular (capillary) columns in standard, commercially available gas chromatographic instrumentation is demonstrated. Key elements in the design and proper utilization of the instrumentation are discussed. The function of the various sample introduction systems is elaborated and their quantitative performance demonstrated. The extra-column contribution to band-spreading is determined and the resultant data is used assessing the suitability of commercial instrumentation for highspeed capillary gas chromatography. The quantitative analysis of a sample containing some eleven components in less than thirty seconds is shown.
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  • 58
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Crystal hydrates as stationary phases ; Mobile Phases containing water ; Selective retentions
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    Topics: Chemistry and Pharmacology
    Notes: Summary The use of crystallohydrates, crystallohydrate solutions and melts as stationary phases in gas chromatography has been proposed. Crystallohydrates have been shown to display high selectivity in the separation of polar organic compounds when use is made of water vapours as the mobile phase. Some aspects of gas-liquid chromatography in water vapours and with the stationary phase comprising crystallohydrates have been studied, and the preliminary results obtained point to the desirability of further progress in this field.
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  • 59
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    Chromatographia 16 (1982), S. 201-203 
    ISSN: 1612-1112
    Keywords: Phenols ; Whisky ; Gas chromatography ; Aroma compounds
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    Topics: Chemistry and Pharmacology
    Notes: Summary Twelve volatile phenols were identified in whisky by combined gas chromatography-mass spectrometry. Of these phenols 2,4-dimethylphenol was found for the first time in the aroma of whisky. The content of phenol, o-, m-, and p-cresol, guaiacol, p-ethylphenol, p-ethylguaiacol and eugenol in whiskies originating from different countries was determined by gas chromatography as their 2,4-dinitrophenyl ethers using electron capture detection. The results show that Scotch whiskies differ from others in the content of o-, m-, and p-cresol. The odour threshold values of phenols studied were determined in a 10% (v/v) ethanol-water mixture and in some cases also in the whiskies. Cresols have been found to make contribution to the aroma of Scotch whisky.
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  • 60
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    Chromatographia 16 (1982), S. 26-31 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Ionization detectors ; Gaia
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    Topics: Chemistry and Pharmacology
    Notes: Summary This paper is an account of the development of the gaia hypothesis as seen through the eyes of a gas chromatographer. Gaia is a radical notion about the Earth which postulates the climate and chemical composition to be regulated at an optimum by and for life. Gas chromatography played an important role in the gathering of evidence for the hypothesis but most significantly the art of inventing detectors lead to the developement of a planetary life detector through which gaia was revealed.
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  • 61
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    Chromatographia 16 (1982), S. 282-285 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Naphtha analysis ; Gasoline analysis ; Hydrocarbon type analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary Two different gas chromatographic methods are used for the determination of hydrocarbon type distribution in naphtha and gasoline samples with final boiling points up to 275 °C. The methods are based either on a single capillary column or on a valve-switched packed column system. Both methods give extensive information on paraffins, olefins, naphthenes and aromatics in total as well as by carbon-number. In each case the analysis is fully automated with a computer controlling the entire analysis from injection to results presentation. The advantages and limitations of both methods are discussed.
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  • 62
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    Chromatographia 16 (1982), S. 322-324 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Graphitized carbon black supports ; Determination of hydroxyacids
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    Topics: Chemistry and Pharmacology
    Notes: Summary Acid-washed graphitized carbon black (Carbopakc B) modified with trimesic adic and PEG 20M has proved to be effective for quantitative analysis of underivatized low molecular weight hydroxyacids. Calibration data revealed good linear relationships between relative peak area and concentration for lactic and 3-hydroxybutyric acids down to 0.05 mmol/l. The packing material was suitable for the analysis of aqueous solutions of hydroxyacids as it is tolerant to injections of water over a prolonged period of use. The GC system developed has been applied to the analysis of some hydroxyacids of biomedical interest in blood plasma and lactic acid contained in wine and beer.
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  • 63
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Modified thermal energy analyzer ; Selective detection of nitrogen compounds
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    Topics: Chemistry and Pharmacology
    Notes: Summary A modification to the TEATM Analyzer is described, which allows it to be used as a highly selective GC detector for nitrogen compounds as well as for N-nitrosamines and nitro compounds. The modified Analyzer is as sensitive as the AFID, but has a much higher selectivity towards nitrogen compounds than the AFID. Its response appears to be molar, with an output that is dependent only on the number of nitrogen atoms present. The performance of the modified Analyzer for the analysis of ammonia, amines,N-nitrosamines, nitriles and organonitro compounds is reported and discussed, as is its application to the detection of these compounds in bacon and beer samples.
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  • 64
    ISSN: 1612-1112
    Keywords: Graphizized carbon black traps ; Organic air pollutants ; Work areas ; Gas chromatography
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    Topics: Chemistry and Pharmacology
    Notes: Summary The use of traps containing graphitized carbon black for the collection and pre-analysis of atmospheric pollutants in industrial areas is presented. The working conditions, in terms of trapping capability and effectiveness of release by thermal desorption are discussed. Some practical applications are also given.
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  • 65
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Van der Waals' volume ; Polarity of stationary phase ; Retention index
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    Topics: Chemistry and Pharmacology
    Notes: Summary Equations for Retention Index (I) versus Van der Waals, volume (Vw) on squalane are studied for alcohols, carbonyls, esters and ethers. Each equation includes linear and branching substances with different positions of the functional group in the carbon chain. The study is extended to stationary phases with polarities from 4.29 to 91.54 on the Tarjan et al. scale. Variations of the slope and origin ordinate values with the polarity of the stationary phase are discussed.
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  • 66
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    Chromatographia 15 (1982), S. 125-132 
    ISSN: 1612-1112
    Keywords: Capillary columns ; Fast analysis ; Gas chromatography ; Instrumental effects ; Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The efficiency of fast GC columns depends largely on the quality of the chromatograph. A theoretical and experimental study shows the relative importance of the various phenomena involved and permits the optimization of a GC System. Extremely good performances, exceeding 2,500 plates per second have been routinely obtained.
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  • 67
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    Chromatographia 15 (1982), S. 180-182 
    ISSN: 1612-1112
    Keywords: Acidic fermentation products ; Characterisation ; Gas chromatography ; Methyl esters
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    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and simple method for the identification of acidic fermentation products is described. Methyl esters of volatile and non-volatile acids are separated on a single chromatographic column. Retention time data for a number of acids are tabulated.
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  • 68
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    Chromatographia 15 (1982), S. 521-524 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index ; Connectivity index ; Van der Waals' volume ; Alkanes
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    Topics: Chemistry and Pharmacology
    Notes: Summary The relationships between retention index and Van der Waals' volume and between retention index and connectivity index have been studied for 58 different alkanes (C1−C9) on squalane. The correlation coefficient for the former is higher than for the latter. From these equations a linear relationship between Van der Waals' volume and connectivity index is obtained which indicates that the two parameters are equivalent. A simple method for calculating the Van der Waals' volume of alkanes is proposed.
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  • 69
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Fused silica capillaries ; Capillary drawing ; Glass capillaries
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    Topics: Chemistry and Pharmacology
    Notes: Summary A compact description is given of a simple and reliable method of drawing flexible fused silica capillary for gas chromatography. Some emphasis is given to the fact that the practices of drawing optical fibres should not be followed too slavishly so this leads to unnecessarily complicated and expensive equipment. Satisfactory capillary column silica tubing can be made with straightfoward extension of the method developed earlier for drawing thick walled capillary. A simple glass/silica hydrogen oxygen diffusion flame bumer is described for fusing the preform tubing at the draw point which is enclosed by a water cooled glass enclosure to trap evaporated silica and maintain the operation under dust free conditions. The uniformity of the capillary diameter is better than 5% which is adequate for most gas chromatographic purposes. The second part of the paper yet to be published will cover the methods developed for coating the capillary both internally and externally.
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  • 70
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    Chromatographia 16 (1982), S. 107-111 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Thermionic ionization ; Catalytic flame ionization
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    Topics: Chemistry and Pharmacology
    Notes: Summary A newly designed thermionic detector was operated in two modes of thermionic ionization detection (TID), and a third mode of catalytic flame ionization detection (CFID). Operating modes were varied by changing the composition of the electrically-heated thermionic/catalytic source, and the composition of gases supplied to the detector. A TID-2 source activated by a low concentration of Cs/ceramic was operated in a dilute H2/air environment and provided specific responses to nitrogen and phosphorus compounds. A TID-1 source activated by a high concentration of Cs/ceramic was operated in a N2 environment and provided very high specificities and picogram detectivities to compounds containing electronegative functional groups such as the NO2 group. A CFID source formed from Ni/ceramic was operated in a H2/air flame environment and provided universal responses to all organics with enhanced responses to some heteroatom compounds.
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  • 71
    ISSN: 1432-0878
    Keywords: Uterus ; Epithelial cells ; Tight junctions ; Pregnancy ; Rat
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    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of tight junctions between uterine luminal epithelial cells of the pregnant rat was studied by the freeze-fracture technique. On day 5 of pregnancy, the day of implantation, the region of tight junctions extended three times as far down the lateral cell membrane as on day 1 of pregnancy, and the strands of the complex interlinked more frequently. These observations suggest that tight junctions on day 5 may be more efficient in preserving the contents of the uterine lumen from dilution or escape than at earlier times of pregnancy.
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  • 72
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    Publication Date: 1982-07-02
    Description: Gastric acid secretion has been thought to depend on histamine stimulation of the parietal cell. However, in the 2-week-old rat neither exogenous histamine nor the H-2 receptor agonist impromidine stimulates acid secretion, whereas pentagastrin and the cholinergic agent bethanechol are potent stimuli. At this age, the effect of pentagastrin in acid secretion is not blocked by the H-2 receptor antagonist cimetidine, nor is it potentiated by impromidine. These data suggest that, in the rat pup, the acid secretory response to pentagastrin and cholinergic agents occurs before the histamine-mediated system is functional and operates independently of the actions of histamine.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ackerman, S H -- K1-MH00077/MH/NIMH NIH HHS/ -- R01-AM-18804/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1982 Jul 2;217(4554):75-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6211765" target="_blank"〉PubMed〈/a〉
    Keywords: Aging ; Animals ; Bethanechol Compounds/pharmacology ; Gastric Juice/drug effects/*secretion ; Gastric Mucosa/growth & development ; Guanidines/pharmacology ; Histamine/pharmacology ; Imidazoles/pharmacology ; Impromidine ; Pentagastrin/pharmacology ; Rats ; Rats, Inbred Strains ; Receptors, Histamine H2/drug effects
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  • 73
    Publication Date: 1982-11-12
    Description: Female athymic nude mice and their phenotypically normal littermates were exposed transplacentally to ethylnitrosourea. Skin tumors (papillomas and sebaceous adenomas) developed on the nude mice with an almost tenfold greater incidence than on their haired littermates. Skin tumors were also induced on nude mice but not haired controls by direct intraperitoneal treatment with ethylnitrosourea. These results indicate that nude mice have higher than normal susceptibility to carcinogenesis under some circumstances.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anderson, L M -- Last-Barney, K -- Budinger, J M -- CA 08748/CA/NCI NIH HHS/ -- CA 22498/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1982 Nov 12;218(4573):682-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7134965" target="_blank"〉PubMed〈/a〉
    Keywords: Adenoma/chemically induced ; Animals ; *Ethylnitrosourea ; Female ; *Maternal-Fetal Exchange ; Mice ; Mice, Nude/*physiology ; Neoplasms, Experimental/chemically induced ; *Nitrosourea Compounds ; Pregnancy ; Sebaceous Gland Neoplasms/chemically induced ; Skin Neoplasms/*chemically induced
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  • 74
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-02-05
    Description: A single identified neuron was repeatedly isolated by axotomy from the central nervous system of the nudibranch mollusk Hermissenda crassicornis. An early voltage-dependent outward K+ current of this neuron was reduced and more rapidly inactivated for animals previously trained with paired but not randomized light and rotation. Since this current change can affect interneuron and motorneuron output via known synaptic pathways, it helps explain a long-lasting behavioral change that shows the defining features of vertebrate associative learning.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alkon, D L -- Lederhendler, I -- Shoukimas, J J -- New York, N.Y. -- Science. 1982 Feb 5;215(4533):693-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7058334" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Association Learning/*physiology ; Central Nervous System/physiology ; Electric Conductivity ; Learning/*physiology ; Membrane Potentials ; Mollusca ; Neurons/*physiology ; Photoreceptor Cells/physiology ; Potassium/*physiology
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  • 75
    Publication Date: 1982-11-26
    Description: Within 1 day after the removal of one branch of the bifurcated axon of an identified neuron in Aplysia, the cell body reduced its output of transmitter storage vesicles to adjust precisely for the decreased need. This adjustment terminated the initial consequence of the removal, the transport of an inappropriately large number of vesicles to the remaining synapses. The most likely cause of the reduction of transport of transmitter is the loss of information normally provided by the disconnected axon or synapses.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aletta, J M -- Goldberg, D J -- GM 07182/GM/NIGMS NIH HHS/ -- NS 14711/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Nov 26;218(4575):913-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6182616" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Aplysia/physiology ; *Axonal Transport ; Axons/*physiology ; Biological Transport ; Cytoplasmic Granules/metabolism ; Intracellular Membranes/metabolism ; Serotonin/*metabolism
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  • 76
    Publication Date: 1982-10-29
    Description: Exposure of rats to cimetidine during intrauterine life and the immediate neonatal period results in hypoandrogenization in adult life with decreased weights of androgen-dependent tissues and decreased concentrations of testosterone. Moreover, sexual behavior patterns in adult life are disturbed as shown by a lack of sexual motivation and decreased performance.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anand, S -- Van Thiel, D H -- New York, N.Y. -- Science. 1982 Oct 29;218(4571):493-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7123252" target="_blank"〉PubMed〈/a〉
    Keywords: Abnormalities, Drug-Induced/*etiology ; Animals ; Animals, Suckling ; Cimetidine/metabolism/*toxicity ; Female ; Guanidines/*toxicity ; Male ; Pregnancy ; Pregnancy, Animal/drug effects ; Rats ; Sex Differentiation/*drug effects ; Sexual Behavior, Animal/drug effects
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  • 77
    Publication Date: 1982-07-30
    Description: As shown previously, laying hens given 1,25-dihydroxyvitamin D3 as their sole source of vitamin D produce fertile eggs having normal shells, but only 35 to 55 percent of the embryos are normal. Giving these hens additional 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D3, or 24,24-difluoro-25-hydroxyvitamin D3 at 1.25 nanomoles per day resulted in 90 to 100 percent normal embryos, and hence, hatchability. Since 24,24-difluoro-25-hydroxyvitamin D3 cannot be 24-hydroxylated, 24-hydroxylation is not required for this function of 25-hydroxyvitamin D3.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ameenuddin, S -- Sunde, M -- DeLuca, H F -- Ikekawa, N -- Kobayashi, Y -- New York, N.Y. -- Science. 1982 Jul 30;217(4558):451-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6979782" target="_blank"〉PubMed〈/a〉
    Keywords: 24,25-Dihydroxyvitamin D 3 ; Animal Feed ; Animals ; Calcifediol ; Calcitriol/analogs & derivatives/pharmacology ; Chick Embryo/*growth & development ; Chickens/metabolism ; Dihydroxycholecalciferols/pharmacology ; Female ; Hydroxycholecalciferols/*metabolism/pharmacology ; Hydroxylation
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  • 78
    Publication Date: 1982-12-10
    Description: Rhodamine-123, a cationic laser dye, markedly reduced the clonal growth of carcinoma cells but had little effect on nontumorigenic epithelial cells in vitro. This selective inhibitory effect of Rhodamine-123 on some carcinomas is unusual since known anticancer drugs, such as arabinosyl cytosine and methotrexate, have not been shown to exhibit such selectivity in vitro.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bernal, S D -- Lampidis, T J -- Summerhayes, I C -- Chen, L B -- New York, N.Y. -- Science. 1982 Dec 10;218(4577):1117-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7146897" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Carcinoma/*drug therapy ; Cell Line ; Cell Survival/drug effects ; Mice ; Mitochondria/metabolism ; Neoplasms, Experimental/drug therapy ; Rhodamine 123 ; Rhodamines/metabolism/therapeutic use ; Time Factors ; Urinary Bladder Neoplasms/drug therapy
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  • 79
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-09-24
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Benveniste, R E -- Todaro, G J -- New York, N.Y. -- Science. 1982 Sep 24;217(4566):1202.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7112123" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Cell Physiological Phenomena ; Eukaryotic Cells/*physiology ; Humans ; *Recombination, Genetic ; Retroviridae/genetics
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  • 80
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-04-30
    Description: Vasoactive intestinal peptide caused a prompt, dose-dependent relaxation of isolated gastric smooth muscle cells of the guinea pig and a significant increase in intracellular adenosine 3',5'-monophosphate coincidentally with optimum relaxation. Relaxation was augmented by a threshold concentration of isobutyl methylxanthine. The direct relaxant effect of vasoactive intestinal peptide and the distribution of nerves containing this peptide to circular smooth muscle support the view that vasoactive intestinal peptide is the neuromuscular transmitter of enteric inhibitory nerves.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bitar, K N -- Makhlouf, G M -- AM-15564/AM/NIADDK NIH HHS/ -- AM-28300/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1982 Apr 30;216(4545):531-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6176025" target="_blank"〉PubMed〈/a〉
    Keywords: 1-Methyl-3-isobutylxanthine/pharmacology ; Animals ; Cyclic AMP/physiology ; Gastrointestinal Hormones/*pharmacology ; Guinea Pigs ; In Vitro Techniques ; Muscle Contraction/*drug effects ; Muscle Relaxation/*drug effects ; Muscle, Smooth/*drug effects ; Neurotransmitter Agents/physiology ; Stomach/drug effects/*innervation ; Vasoactive Intestinal Peptide/*pharmacology
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  • 81
    Publication Date: 1982-06-25
    Description: Golden Syrian hamsters were placed individually in cages with three drinking bottles--one empty, one containing water, and the third containing water and ethanol. Control hamsters received water only. After 1 year the experimental hamsters showed a significantly lower concentration of leucine-enkephalin-like immunoreactive substance in the basal ganglia than the control hamsters. This finding indicates that the action of ethanol involves endogenous peptidyl opiates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blum, K -- Briggs, A H -- Elston, S F -- DeLallo, L -- Sheridan, P J -- Sar, M -- New York, N.Y. -- Science. 1982 Jun 25;216(4553):1425-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7089531" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Basal Ganglia/*drug effects ; Cricetinae ; Endorphins/*analysis ; Enkephalin, Leucine ; Enkephalins/*analysis/metabolism ; Ethanol/metabolism/*pharmacology ; Mesocricetus ; Time Factors
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  • 82
    Publication Date: 1982-02-19
    Description: As reticulocytes mature into erythrocytes, organelles and many enzymes are lost. Protein degradation during reticulocyte maturation was measured by monitoring the release of tyrosine from cell proteins. Proteolysis in rabbit red blood cells was directly proportional to the number of reticulocytes and was low in erythrocytes. This process was inhibited by blockers of cellular adenosine triphosphate production and by agents, such as o-phenanthroline, N-ethylmaleimide, and hemin, which inhibit the soluble adenosine triphosphate-dependent proteolytic system. The breakdown of endogenous proteins in reticulocyte extracts was also inhibited by these agents and required adenosine triphosphate. Inhibitors of lysosomal function, however, did not affect proteolysis. Thus, the proteolytic system that degrades abnormal proteins also catalyzes the elimination of proteins during red cell development.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Boches, F S -- Goldberg, A L -- New York, N.Y. -- Science. 1982 Feb 19;215(4535):978-80.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7156977" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/*physiology ; Animals ; Blood Proteins/*metabolism ; Cell Differentiation ; Cyclophosphamide/pharmacology ; Deoxyglucose/pharmacology ; Dinitrophenols/pharmacology ; Lysosomes/enzymology ; Rabbits ; Reticulocytes/*physiology ; Tyrosine/analysis
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  • 83
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-07-16
    Description: A method has been developed for the measurement of intracellular free calcium in mammalian cells. The calcium-sensitive photoprotein aequorin can be incorporated into isolated cells by hypo-osmotic treatment without altering the cell viability, permeability, or metabolism. Intracellular calcium activity (Cai2+) was monitored in a perfusion system. In monkey kidney cells (LLC-MK2), Cai2+ is approximately 57 nanomoles per liter. Changes in Cai2+ with time can also be followed: exposure of the cells to anaerobiosis or the calcium ionophore A23187 reversibly increases Cai2+. The method has also been successfully tested in rat hepatocytes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Borle, A B -- Snowdowne, K W -- New York, N.Y. -- Science. 1982 Jul 16;217(4556):252-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6806904" target="_blank"〉PubMed〈/a〉
    Keywords: *Aequorin ; Anaerobiosis ; Animals ; Calcimycin/pharmacology ; Calcium/*metabolism ; Cell Line ; Kidney/drug effects/*metabolism ; Kinetics ; *Luminescent Proteins ; Macaca mulatta
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  • 84
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-08-20
    Description: Mice will replace the tip of a foretoe when it is amputated distal to the last interphalangeal joint. Amputation of the digit more proximal to the joint does not result in regrowth of the foretoe. Though this growth shares certain similarities with the epimorphic regeneration of amphibian limbs, the two processes are not the same. The regrowth reported here in mice is probably similar to the scattered clinical reports of fingertips regeneration in children, and presents a model system with which to explore the controls of wound healing and tissue reconstruction in mammals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Borgens, R B -- CA 20920/CA/NCI NIH HHS/ -- NS 18456/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Aug 20;217(4561):747-50.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7100922" target="_blank"〉PubMed〈/a〉
    Keywords: Amputation ; Animals ; Child ; Humans ; Mice ; Mice, Inbred C3H ; *Regeneration ; Toe Joint ; Toes/anatomy & histology/*physiology ; Wound Healing
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  • 85
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-05-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bowden, D M -- New York, N.Y. -- Science. 1982 May 14;216(4547):682, 684.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7079726" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Animals, Laboratory ; *Research Design
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  • 86
    Publication Date: 1982-06-11
    Description: Receptors that selectively bind micromolar concentrations of benzodiazepines are present in rat brain membrane. These micromolar receptors exhibit saturable, stereospecific binding, and the potency of benzodiazepine binding to these receptors is correlated with the ability of the benzodiazepines to inhibit maximum electric shock-induced convulsions. Benzodiazepine receptors with nanomolar affinity differ from the micromolar receptors in their binding, kinetic, and pharmacologic characteristics. The micromolar receptors also bind phenytoin, a non-benzodiazepine anticonvulsant. These results provide evidence for a distinct class of clinically relevant benzodiazepine receptors that may regulate neuronal excitability and anticonvulsant activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bowling, A C -- DeLorenzo, R J -- NS 1352/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Jun 11;216(4551):1247-50.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6281893" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Benzodiazepines/*metabolism/pharmacology ; Benzodiazepinones/metabolism ; Brain/*metabolism ; Calmodulin/antagonists & inhibitors ; Diazepam/metabolism ; Kinetics ; Ligands ; Protein Kinase Inhibitors ; Rats ; Receptors, Drug/*metabolism ; Receptors, GABA-A ; Structure-Activity Relationship
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  • 87
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-12-10
    Description: Development of video-enhanced contrast-differential interference contrast for light microscopy has permitted study of both orthograde and retrograde fast axonal transport of membranous organelles in the squid giant axon. This process was found to continue normally for hours after the axoplasm was extruded from the giant axon and removed from the confines of the axonal plasma membrane. It is now possible to follow the movements of the full range of membranous organelles (30-nanometer vesicles to 5000-nanometer mitochondria) in a preparation that lacks a plasma membrane or other permeability barrier. This observation demonstrates that the plasma membrane is not required for fast axonal transport and suggests that action potentials are not involved in the regulation of fast transport. Furthermore, the absence of a permeability barrier surrounding the axoplasm makes this an important model for biochemical pharmacological, and physical manipulations of membranous organelle transport.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brady, S T -- Lasek, R J -- Allen, R D -- GM27284/GM/NIGMS NIH HHS/ -- NS07118/NS/NINDS NIH HHS/ -- NS15731/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Dec 10;218(4577):1129-31.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6183745" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/physiology ; Animals ; *Axonal Transport ; Axons/*physiology ; Biological Transport, Active ; Cell-Free System ; Cytoplasmic Granules/physiology ; Cytoskeleton/physiology ; Decapodiformes ; Intracellular Membranes/physiology ; Microscopy/methods ; Microtubules/physiology ; Motion Pictures as Topic
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  • 88
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-08-06
    Description: Spinal cord damage in neonatal cats has different effects on different spinal pathways. Corticospinal projections exhibit anatomical plasticity, forming an aberrant pathway that bypasses the lesion. In contrast, brainstem-spinal pathways undergo massive retrograde degeneration. Neither of these responses occurs in adult cats. Sparing of motor function is found in cats operated on as neonates but not in cats operated on as adults, and appears to depend on the plasticity of the corticospinal tract.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bregman, B S -- Goldberger, M E -- GM06772/GM/NIGMS NIH HHS/ -- NS16629/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Aug 6;217(4559):553-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7089581" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Animals, Newborn/*physiology ; Brain Stem/pathology ; Cats/*physiology ; Horseradish Peroxidase/metabolism ; Motor Activity/physiology ; Motor Cortex/pathology ; Neural Pathways/physiopathology ; *Neuronal Plasticity ; Neurons, Efferent/metabolism ; Retrograde Degeneration ; Spinal Cord Injuries/*physiopathology
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  • 89
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-11-05
    Description: Simple chemical catalysts have been designed to achieve some desirable features of enzymes. These novel catalysts are not proteins, but they may incorporate the typical enzyme catalytic groups and they achieve selectivity in their reactions by use of geometric control, as do enzymes. Catalysts that carry out geometrically controlled chlorinations of aromatic rings and steroids have been constructed. Other catalysts achieve the selective synthesis of amino acids, and still others imitate ribonuclease in detailed mechanism and hydrolyze RNA. Optimization of geometries has led to a rate acceleration of over 10(8) in one instance.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Breslow, R -- New York, N.Y. -- Science. 1982 Nov 5;218(4572):532-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7123255" target="_blank"〉PubMed〈/a〉
    Keywords: Catalysis ; Cyclodextrins ; *Enzymes ; Kinetics ; Models, Chemical ; Ribonucleases ; Structure-Activity Relationship ; Substrate Specificity ; Transaminases
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  • 90
    Publication Date: 1982-01-08
    Description: (+/-)-N-Allylnormetazocine is a benzomorphan opioid with psychotomimetic effects. The pure stereoisomers of this compound, as well as the racemic mixture, were compared to phencyclidine for their behavioral effects on squirrel monkeys and rats trained to discriminate phencyclidine from saline. Dose-response determinations were made for responses to phencyclidine, to a racemic mixture of N-allylnormetazocine, and to the pure levo and dextro isomers of N-allylnormetazocine. In both rats and monkeys, the dextro isomer and the racemic mixture produced dose-dependent responses appropriate for phencyclidine; the levo isomer did not produce the responses appropriate for phencyclidine at any of the doses tested. In both species, the levo isomer was more potent than the dextro isomer in decreasing the rate of responding. Thus racemic N-allylnormetazocine is a mixture of compounds that produce different behavioral effects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brady, K T -- Balster, R L -- May, E L -- DA-00490/DA/NIDA NIH HHS/ -- DA-01442/DA/NIDA NIH HHS/ -- New York, N.Y. -- Science. 1982 Jan 8;215(4529):178-80.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6274022" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal/*drug effects ; Male ; Naloxone/pharmacology ; Phenazocine/*analogs & derivatives/pharmacology ; Phencyclidine/pharmacology ; Rats ; Rats, Inbred Strains ; Receptors, Opioid/drug effects ; Saimiri ; Stereoisomerism ; Structure-Activity Relationship
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  • 91
    Publication Date: 1982-10-08
    Description: Rats whose pregnancies were surgically terminated on day 17 of gestation were injected with morphine, morphine plus naloxone hydrochloride, or saline, and then tested for maternal responsiveness toward foster young. Morphine treatment alone significantly disrupted the rate of onset and quality of maternal responsiveness. Concurrent administration of naloxone to morphine-injected rats reinstated the rapid onset of behavioral responsiveness toward foster young, such that the responsiveness of the rats treated with both morphine and naloxone was indistinguishable from that shown by saline-injected controls. The disruptive effects of morphine did not appear to result from a general reduction in activity levels as measured in an open-field apparatus. These findings suggest that the normal onset and maintenance of maternal behavior in the rat may be regulated by endogenous opiates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bridges, R S -- Grimm, C T -- New York, N.Y. -- Science. 1982 Oct 8;218(4568):166-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7123227" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal/*drug effects ; Drug Antagonism ; Female ; Morphine/*pharmacology ; Naloxone/*pharmacology ; Pregnancy ; Rats ; Rats, Inbred Strains
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  • 92
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-12-10
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cartmill, M -- New York, N.Y. -- Science. 1982 Dec 10;218(4577):1145.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6983135" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Humans ; Primates/*genetics ; T-Lymphocytes/*immunology
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  • 93
    Publication Date: 1982-07-02
    Description: Instantaneous stiffness of frog skeletal muscle, an indication of the proportion of attached crossbridges, was determined drug the tetanus rise and after a step length change imposed during the tetanus plateau. During the onset of contraction as well as after a step, the ratio of stiffness to force differed from that determined during the tetanus plateau. The data after a step are predicted by the Huxley-Simmons model of muscular contraction, but the results during the rise suggest that a long-lived state may exist between crossbridge attachment and force generation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cecchi, G -- Griffiths, P J -- Taylor, S -- NS 14268/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Jul 2;217(4554):70-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6979780" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Mathematics ; *Muscle Contraction ; Muscles/physiology/ultrastructure ; Rana temporaria
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  • 94
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-03-12
    Description: Brief tetanic stimulation of the preganglionic nerves to the superior cervical ganglion enhances the postganglionic response to single preganglionic stimuli for 1 to 3 hours. This long-term potentiation of transmission through the ganglion is apparently not attributable to a persistent muscarinic action of the preganglionic neurotransmitter, acetylcholine, since neither the magnitude nor the time course of the phenomenon is reduced by atropine. The decay of long-term potentiation can be described by a first-order kinetic process with a mean time constant of 80 minutes. We conclude that long-term potentiation, once considered a unique property of the hippocampus, is in fact a more general feature of synaptic function. This form of synaptic memory may significantly influence information processing and control in other regions of the nervous system, including autonomic ganglia.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brown, T H -- McAfee, D A -- 12116/PHS HHS/ -- NS 16576/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Mar 12;215(4538):1411-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6278593" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Ganglia, Sympathetic/*physiology ; Kinetics ; Learning/*physiology ; Neuronal Plasticity ; Rats ; Synapses/*physiology ; *Synaptic Transmission ; Time Factors
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  • 95
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-08-06
    Description: Depletion of glutathione in Chinese hamster ovary cells in vitro by diethyl maleate resulted in enhancement of the effect of x-rays on cell survival under hypoxic conditions but not under oxygenated conditions. Hypoxic EMT6 tumor cells were similarly sensitized in vivo. The action of diethyl maleate is synergistic with the effect of the electron-affinic radiosensitizer misonidazole, suggesting that the effectiveness of misonidazole in cancer radiotherapy may be improved by combining it with drugs that deplete intracellular glutathione.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bump, E A -- Yu, N Y -- Brown, J M -- CA-15201/CA/NCI NIH HHS/ -- CM-87207/CM/NCI NIH HHS/ -- New York, N.Y. -- Science. 1982 Aug 6;217(4559):544-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7089580" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anoxia ; Cell Survival/drug effects/*radiation effects ; Cells, Cultured ; Cricetinae ; Cricetulus ; Drug Synergism ; Glutathione/*metabolism ; Maleates/administration & dosage ; Mice ; Mice, Inbred BALB C ; Misonidazole/administration & dosage ; Neoplasms, Experimental/metabolism ; *Oxygen Consumption
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  • 96
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-09-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cowan, M D -- New York, N.Y. -- Science. 1982 Sep 3;217(4563):884.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7112101" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Carcinogens ; Humans ; Occupational Diseases/chemically induced ; United States ; *United States Occupational Safety and Health Administration
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  • 97
    Publication Date: 1982-07-30
    Description: The messenger RNA for a beta-crystallin polypeptide with a molecular size of 27 kilodaltons, first detected 5 to 10 days after birth in the normal mouse lens and the Nakano mouse cataract, was not detected in the Philly mouse cataract with translation in vitro. The heterozygous Philly lens had intermediate levels of the 27-kilodalton beta-crystallin polypeptide and exhibited delayed onset of the cataract. The deficiency of functional 27-kilodalton beta-crystallin messenger RNA is the earliest lesion reported yet for the Philly lens and points to a transcriptional or posttranscriptional developmental defect in this hereditary cataract.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Carper, D -- New York, N.Y. -- Science. 1982 Jul 30;217(4558):463-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6178163" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cataract/*genetics ; Cell-Free System ; Crosses, Genetic ; Crystallins/*genetics ; Mice ; Mice, Inbred Strains ; Protein Biosynthesis ; Proteins ; RNA/genetics ; RNA Splicing ; RNA, Messenger/*genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 98
    Publication Date: 1982-01-15
    Description: The electrophysiological effects of ethanol in low doses (5 to 20 millimoles per liter or 23 to 92 milligrams per 100 milliliters) were examined intracellularly in CA1 cells of rat hippocampus in vitro. Inhibitory and excitatory postsynaptic potentials were increased when ethanol was applied to the respective synaptic terminal regions. Postsynaptically, ethanol caused a moderate hyperpolarization with increased membrane conductance, even when synaptic transmission was blocked. Ethanol augmented the hyperpolarization that followed repetitive firing or that followed the eliciting of calcium spikes in the presence of tetrodotoxin, but not the rapid afterhyperpolarization in calcium-free medium. Ethanol appears to augment calcium-mediated mechanisms both pre- and postsynaptically.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Carlen, P L -- Gurevich, N -- Durand, D -- R01 NS16660-01/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Jan 15;215(4530):306-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7053581" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/physiology ; Electric Conductivity ; Ethanol/*pharmacology ; Hippocampus/*drug effects/physiology ; Male ; Membrane Potentials/drug effects ; Potassium/physiology ; Rats ; Rats, Inbred Strains ; Synaptic Membranes/drug effects ; Tetrodotoxin/pharmacology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 99
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-10-01
    Description: Mouse embryos were grown successfully in vitro from the blastocyst stage to the limb bud stage. Mouse blastocysts grown in vitro for 10 days showed blood circulation in the yilk sac, forelimb buds, and the primordia of liver, pancreas, and lungs. These characteristics are indicative of a developmental stage equivalent to one-half of the total gestation period in utero. Improvements in culture conditions from days 7 to 9 have made it feasible to culture mouse blastocysts beyond the early somite stage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, L T -- Hsu, Y C -- AM 19535/AM/NIADDK NIH HHS/ -- AM 28550/AM/NIADDK NIH HHS/ -- New York, N.Y. -- Science. 1982 Oct 1;218(4567):66-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7123220" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blastocyst/*physiology ; Cell Differentiation ; Culture Media ; Culture Techniques ; Embryo, Mammalian/*physiology ; Female ; Fetal Blood ; Humans ; Mice ; Pregnancy ; Yolk Sac/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 100
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1982-05-07
    Description: The activity of angiotensin-converting enzyme is significantly higher in the intermediate and posterior pituitary lobes of Brattleboro rats than in Long-Evans control rats. The high activity level was reversed by vasopressin treatment. Conversely, angiotensin-converting enzyme activity was significantly lower in the anterior pituitary of Brattleboro rats than in Long-Evans rats, and this activity level was not affected by vasopressin. these findings suggest an inverse relation between vasopressin and angiotensin systems in the posterior and intermediate lobes of the pituitary gland.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chevillard, C -- Saavedra, J M -- New York, N.Y. -- Science. 1982 May 7;216(4546):646-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6280284" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Diabetes Insipidus/*enzymology/genetics ; Disease Models, Animal ; Peptidyl-Dipeptidase A/*metabolism ; Pituitary Gland, Posterior/*enzymology ; Rats ; Rats, Mutant Strains/*physiology ; Vasopressins/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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