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  • 1995-1999  (60)
  • 1990-1994  (95)
  • 1900-1904  (14)
  • Polymer and Materials Science  (66)
  • Crystal Structure  (40)
  • Organic Chemistry  (31)
  • Life and Medical Sciences  (25)
  • Computational Chemistry and Molecular Modeling
  • Microbial biomass
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Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    The photovoltaic stability of, bis(isothiocyanato)rlutheniurn(II)-bis-2, 2′bipyridine-4, 4′-dicarboxylic acid and related sensitizersSupport of this work by the european joule III program is gratefully acknowledged. (1997)
    Weinheim : Wiley-Blackwell
    Advanced Materials 9 (1997), S. 904-906 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19970091111
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  • 2
    Electronic Resource
    Electronic Resource
    The kinetics of diastereomeric amino acids with o-phthaldialdehyde (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 471-475 
    Details
    ISSN: 0899-0042
    Keywords: amino acids ; kinetics ; epimers ; OPA ; postcolumn reaction detection ; fluorescence detection ; amino acid racemization ; dating methods ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the reaction of the amino acid epimers L-isoleucine, D-alloisoleucine, L-threonine, and D-allo-threonine with o-phthaldialdehyde and mercaptoethanol were determined at 25°C. L-Isoleucine reacts faster than its D-epimer whereas L-threonine reacts slightly slower than its D-epimer. In the case of isoleucine, the consequence can be an allo/iso ratio which in the worst case is 25% too low if these amino acids are quantified by liquid chromatography and o-phthaldialdehyde fluorescence detection. The effect on dating of fossils by amino acid racemization is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030611
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Ergosterol and microbial biomass relationship in soil (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 299-304 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Fungal biomass ; Ergosterol ; Fumigation extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ergosterol and microbial biomass C were measured in 26 arable, 16 grassland and 30 forest soils. The ergosterol content ranged from 0.75 to 12.94 μg g-1 soil. The geometric mean ergosterol content of grassland and forest soils was around 5.5 μg g-1, that of the arable soils 2.14 μg g-1. The ergosterol was significantly correlated with biomass C in the entire group of soils, but not in the subgroups of grassland and forest soils. The geometric mean of the ergosterol: microbial biomass C ratio was 6.0 mg g-1, increasing in the order grassland (5.1), arable land (5.4) and woodland (7.2). The ergosterol:microbial biomass C ratio had a strong negative relationship with the decreasing cation exchange capacity and soil pH, indicating that the fungal part of the total microbial biomass in soils increased when the buffer capacity decreased. The average ergosterol concentration calculated from literature data was 5.1 mg g-1 fungal dry weight. Assuming that fungi contain 46% C, the conversion factor from micrograms ergosterol to micrograms fungal biomass C is 90. For soil samples, neither saponification of the extract nor the more effective direct saponification during extraction seems to be really necessary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334573
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  • 4
    Electronic Resource
    Electronic Resource
    The problem of pretreatment and unintentional variations in the fumigation-extraction method for time-course measurements in the field (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 167-170 
    Details
    ISSN: 1432-0789
    Keywords: Analytical variations ; Root intenference ; Root pre-extraction ; Fumigation-extraction ; Microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A control soil stored at 4°C was analyzed 38 times by fumigation-extraction during a period of 11 months to correct for variations caused by the analytical procedure. The difference in extractable C between fumigated and unfumigated samples oscillated around the average without a positive or negative trend. When data from contemporaneously extracted field samples were corrected with control soil data the variations were lowered. The deviations between corrected and uncorrected biomass C values had maxima of ±12%. Data obtained for seven dates using pre-extraction, wet-sieving, and centrifuging were compared with data obtained by the conventional procedure without any pretreatment. A negative difference from data obtained without pretreatment was found when the soil water content was decreased to 6%. The largest positive difference (+38%) was found in May during the period of highest root growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384450
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  • 5
    Electronic Resource
    Electronic Resource
    Microbial biomass phosphorus in soils of beech (Fagus sylvatica L.) forests (1995)
    Springer
    Biology and fertility of soils 19 (1995), S. 215-219 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Acidification ; Beech forest ; Soil organic C ; Total P ; Fagus sylvatica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty-eight soils from forest sites in central Germany dominated by beech trees (Fagus sylvatica L.) were sampled to a depth of about 10 cm after careful removal of the overlying organic layers. Microbial biomass P was estimated by the fumigation — extraction method, measuring the increase in NaHCO3-extractable phosphate. The size of the microbial P pool varied between 17.7 and 174.3 μg P g-1 soil and was on average more than seven times larger than NaHCO3-extractable phosphate. Microbial P was positively correlated with soil organic C and total P, reflecting the importance of soil organic matter as a P source. The mean microbial P concentration was 13.1% of total P, varying in most soils between 6 and 18. Microbial P and microbial C were significantly correlated with each other and had a mean ratio of 14.3. A wide (5.1–26.3) microbial C: P ratio indicates that there is no simple relatinship between these two parameters. The microbial C: P ratio showed strong and positive correlations with soil pH and cation exchange capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336162
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  • 6
    Electronic Resource
    Electronic Resource
    The problem of pretreatment and unintentional variations in the fumigation-extraction method for time-course measurements in the field (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 167-170 
    Details
    ISSN: 1432-0789
    Keywords: Key words Analytical variations ; Root interference ; Root pre-extraction ; Fumigation-extraction ; Microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A control soil stored at 4°C was analyzed 38 times by fumigation-extraction during a period of 11 months to correct for variations caused by the analytical procedure. The difference in extractable C between fumigated and unfumigated samples oscillated around the average without a positive or negative trend. When data from contemporaneously extracted field samples were corrected with control soil data the variations were lowered. The deviations between corrected and uncorrected biomass C values had maxima of ±12%. Data obtained for seven dates using pre-extraction, wet-sieving, and centrifuging were compared with data obtained by the conventional procedure without any pretreatment. A negative difference from data obtained without pretreatment was found when the soil water content was decreased to 6%. The largest positive difference (+38%) was found in May during the period of highest root growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384450
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  • 7
    Electronic Resource
    Electronic Resource
    Activity and biomass of soil microorganisms at different depths (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 38-42 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Depth profile ; Fumigation-extraction method ; Soil organic matter ; Dormant population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We measured microbial biomass C and soil organic C in soils from one grassland and two arable sites at depths of between 0 and 90 cm. The microbial biomass C content decreased from a maximum of 1147 (0–10 cm layer) to 24 μg g-1 soil (70–90 cm layer) at the grassland site, from 178 (acidic site) and 264 μg g-1 soil (neutral site) at 10–20 cm to values of between 13 and 12 μg g-1 soil (70–90 cm layer) at the two arable sites. No significant depth gradient was observed within the plough layer (0–30 cm depth) for biomass C and soil organic C contents. In general, the microbial biomass C to soil organic C ratio decreased with depth from a maximum of between 1.4 and 2.6% to a minimum of between 0.5 and 0.7% at 70–90 cm in the three soils. Over a 24-week incubation period at 25°C, we examined the survival of microbial biomass in our three soils at depths of between 0 and 90 cm without external substrate. At the end of the incubation experiment, the contents of microbial biomass C at 0–30 cm were significantly lower than the initial values. At depths of between 30 and 90 cm, the microbial biomass C content showed no significant decline in any of the four soils and remained constant up to the end of the experiment. On average, 5.8% of soil organic C was mineralized at 0–30 cm in the three soils and 4.8% at 30–90 cm. Generally, the metabolic quotient qCO2 values increased with depth and were especially large at 70–90 cm in depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335816
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  • 8
    Electronic Resource
    Electronic Resource
    Thermodynamic cycle-perturbation study of the binding of trifluoroacetyl dipeptide anilide inhibitors with porcine pancreatic elastase (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 773-780 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variety of results of crystallographic studies of the serine proteases complexed with isocoumnrin inhibitors presents a challenging problem to modeling methods and molecular energetics. Therefore, the thermodynamic cycle-perturbation technique has been used to study a model system of elastase and two peptidic inhibitors. Using the program AMBER, the technique correctly predicts changes of the binding constants for the trifluoroacetyl dipeptide inhibitors in comparison with available experimental (kinetic and crystallographic) data. However, the absolute values obtained are shown to be sensitive to the specific electrostatic interaction potential parameters used in the simulations. The reader and user are cautioned that thermodynamic cyle-perturbation results may be too optimistic by underestimating the accuracy of free energy values. This is especially a matter of concern for those cases where a direct comparison with experimental values is not possible, viz., (1) the simulation of binding of novel compounds, (2) structurally uncertain binding sites, or (3) structurally different binding modes. With our best 4-31G* ESP (electrostatic potential) charges we were able to reproduce experimentally determined free energy differences (ΔΔA) with an accuracy of about 1.5 kcal/mol. Dynamically induced structural changes in the binding site of elastase, and particularly changes in hydrogen-bond patterns of the binding site, are also reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360300712
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  • 9
    Electronic Resource
    Electronic Resource
    Solution behavior of α-chymotrypsin dissolved in nonpolar organic solvents via hydrophobic ion pairing (1995)
    New York : Wiley-Blackwell
    Biopolymers 35 (1995), S. 451-456 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dissolution of α-chymotrypsin in nonpolar organic solvents can be achieved using hydrophobic ion pairing, whereby the polar counterions are replaced by a stoichiometric number of detergent molecules. Using Aerosol OT[AOT, sodium bis(2-octyl)sulfosuccinate], it is possible to partition significant amounts of the enzyme into alkanes and chlorocarbons. Apparent solubility in isooctane is greater than 1 mg/mL (80 μM). Necessary conditions for achieving effective partitioning of α-chymotrypsin into these solvents are described. Using CD spectroscopy, it can be shown that the AOT-α-chymotrypsin (CMT) complex retains its native secondary and tertiary structure when dissolved in alkanes, and that the globular structure is stable to more than 100°C. In contrast, α-chymotrypsin unfolds at 54°C in aqueous solution. The relative solubility of the AOT-CMT complex in a variety of alkanes and chlorocarbons is also reported. The native structure of α-chymotrypsin is maintained in carbon tetrachloride, but not in methylene chloride or chloroform. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360350504
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  • 10
    Electronic Resource
    Electronic Resource
    Correlation between microscopic structural parameters and macroscopic flow behaviour of some polymer-surfactant systems suitable for tertiary oil recovery (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 57-77 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Einige für den kombinierten Polymer-Tensid-Einsatz in der tertiären Erdölförderung (EOR) diskutierte Substanzen wurden mittels statischer und dynamischer Lichtstreuung charakterisiert und bezüglich ihrer Anwendbarkeit in unterschiedlich salinaren Modellwässern durch rheologische und rheologisch-dynamische Messungen unter-sucht.Als Polymere wurden Xanthan sowie unterschiedlich hydrolysierte Polyacrylamide verwendet, als Tensid ein Ethylenglykolsulfonat. Es ließen sich Korrelationen zwischen mikroskopischen Strukturparametern (z. B. hydrodynamischer Radius, Trägheitsradius, Molekulargewicht, Gestaltparameter der gelösten Polymeren) und makroskopischem Verhalten wie Viskosität aufstellen, welche für den EOR-Einsatz wichtige rheologische Parameter darstellen.Mit ergänzenden Messungen (Oberflächenspannung, zeitabhängiges Viskositätsverhalten) können Aussagen über die Effizienz und Langzeitstabilität eingesetzter Polymer-Tensid-Slugs in unterschiedlich salinaren Lagerstätten gemacht werden.
    Notes: Some materials, suitable for application in polymer-surfactant flooding used in tertiary oil recovery (EOR), have been characterized by static and dynamic light scattering and studied in respect to their suitability in various model brines by measuring their rheological and dynamic-rheological behaviour. Xanthan and polyacrylamides of different degree of hydrolysis have been used as polymers, an ethylene glycol sulfonate as surfactant.Correlations have been established between microscopic structural parameters (Hydrodynamic radius, radius of gyration, molar mass, shape of the polymers) and the macroscopic behaviour, such as viscosity and elasticity, being important rheological parameters for EOR application. Additional investigations on surface tension and long term viscosity study lead then to a judgement for the efficiency and long term stability of polymer-surfactant slugs in various reservoirs of different salinity.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051950104
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