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  • Triticum aestivum  (70)
  • nitrogen  (69)
  • DSC  (48)
  • Fisheries
  • General Chemistry
  • Theoretical, Physical and Computational Chemistry
  • Springer  (189)
  • 1995-1999  (189)
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  • 1940-1944
  • 1996  (189)
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  • 1995-1999  (189)
  • 1945-1949
  • 1940-1944
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  • 1
    ISSN: 1570-7458
    Keywords: Bemisia argentifolii ; Encarsia formosa ; poinsettia ; parasitoids ; nitrogen ; tri-trophic level interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract More wasps of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were found on fertilized poinsettias, Euphorbia pulcherrima (Willd.) (Euphorbiaceae), than on non-fertilized plants. Parasitization of Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) by E. formosa was higher on plants treated with calcium nitrate than with ammonium nitrate or on control plants. In a no-choice test, host feeding by E. formosa was higher when hosts were on fertilized plants than when hosts were on control plants. The nitrogen content of whitefly pupae reared on plants treated with ammonium nitrate was higher than those on calcium nitrate-treated plants. Variability in the parasitization of B. argentifolii by E. formosa appears to be due to host plant-mediated differences in the whiteflies. E. formosa may be influenced by the nutritional suitability of the host, which influences whether wasps continue to oviposit, feed, or disperse.
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  • 2
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    Catalysis letters 37 (1996), S. 163-165 
    ISSN: 1572-879X
    Keywords: nitrogen ; Rh(111) ; thermal desorption ; Arrhenius parameters ; lateral interactions ; NO decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Associative desorption of N atoms from the Rh(111) surface is simulated in the framework of the lattice-gas model. The Arrhenius parameters and nearest-neighbour lateral interaction employed to describe the measured thermal desorption spectra are as follows:v=1013 s−1,E d=40 kcal/mol, and ε1=1.7 kcal/mol. The results obtained are used to clarify the role of nitrogen desorption in the NO + CO reaction on Rh(111) atT=400–700 K andP NO≈P CO≈0.01 atm.
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  • 3
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and croplant under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha-1. Humus losses varied from 0.9% to 3.1%.
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  • 4
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: Key words CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and cropland under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha–1. Humus losses varied from 0.9% to 3.1%.
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  • 5
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    Biology and fertility of soils 23 (1996), S. 273-281 
    ISSN: 1432-0789
    Keywords: Wheat ; Triticum aestivum ; Rhizosphere ; Soil microflora ; Gram-negative bacteria ; API 20 NE ; Flavobacterium spp ; Cytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson's test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.
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  • 6
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    Nutrient cycling in agroecosystems 46 (1996), S. 81-90 
    ISSN: 1573-0867
    Keywords: elemental sulfur ; granule size ; nitrogen ; phosphorus ; potassium ; S oxidation ; sulfur fertilizers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were undertaken to determine the effect of granule size and nutrients in granulated compound fertilizers fortified with finely divided elemental sulfur (So) on the rate of So oxidation. In one experiment, So was banded together with or apart from triple superphosphate (TSP) while in two others, So was granulated with nutrient and inert carriers. A fourth experiment examined response to S in an So-fortified TSP from a range of granule sizes. Response and, in some cases, So recovery (using 35S labels) by test crops (maize, wheat, upland rice) was measured. In all experiments, P mixed with So increased plant growth and S recovery above treatments in which P and So were physically separated. There was however, no effect of distance of separation on S recovery. In one experiment, N as urea and N and P as diammonium phosphate (DAP) were also found to enhance response to So although to a lesser degree than P alone. These observations were attributed to a nutritional requirement of So-oxidizing microorganisms for P and N. Granulation of So with carriers also influenced oxidation rate, as inferred from the fertilizer S recovery. For a given So concentration, the effect was inversely proportional to the mean diameter of granules. It is shown that this relationship can be explained if one assumes that So particles in granules collapse into a fixed number of aggregates per granule irrespective of granule size when the soluble nutrient carrier dissolves and diffuses away from the point of application.
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  • 7
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    Nutrient cycling in agroecosystems 46 (1996), S. 53-70 
    ISSN: 1573-0867
    Keywords: crop ; emission ; fertilizer ; nitrogen ; nitrous oxide ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This analysis is based on published measurements of nitrous oxide (N2O) emission from fertilized and unfertilized fields. Data was selected in order to evaluate the importance of factors that regulate N2O production, including soil conditions, type of crop, nitrogen (N) fertilizer type and soil and crop management. Reported N2O losses from anhydrous ammonia and organic N fertilizers or combinations of organic and synthetic N fertilizers are higher than those for other types of N fertilizer. However, the range of management and environmental conditions represented by the data set is inadequate for use in estimating emission factors for each fertilizer type. The data are appropriate for estimating the order of magnitude of emissions. The longer the period over which measurements are made, the higher the fertilizer-induced emission. Therefore, a simple equation to relate the total annual direct N2O−N emission (E) from fertilized fields to the N fertilizer applied (F), was based on the measurements covering periods of one year: E=1+1.25×F, with E and F in kg N ha-1 yr-1. This relationship is independent of the type of fertilizer. Although the above regression equation includes considerable uncertainty, it may be appropriate for global estimates.
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  • 8
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    Nutrient cycling in agroecosystems 46 (1996), S. 179-187 
    ISSN: 1573-0867
    Keywords: electrical conductivity ; leaching ; nitrogen ; pH ; phosphorus ; potassium ; release pattern ; slow-release fertilizers ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effect of temperature on the release of N, P, and K from slow-release fertilizers (SRF). The study was conducted in micro-lysimeters filled with moist peat medium. Increasing the temperature from 4 to 12°C slightly increased N release from three different slow-release N (SRN) carriers with different particle sizes and coating thicknesses. At 21°C the rate of release was significantly different than the other two temperatures. Urea formaldehyde (UF), sulphur coated urea (SCU) and coated calcium nitrate (CCN), incubated in sphagnum moss peat, released between 3 and 20% of the applied N in six weeks. For eight synthetic and organic NPK carriers, the release pattern was similar to UF and SCU. However, the leaching losses of N from the NPK fertilizers were up to twenty times more than for the SRN products. Except for Osmocote® and Duna, which released 30–40% of the applied N as mineral-N within six weeks, all other slow-release and slowly mineralized NPK carriers acted like readily water-soluble compound NPK. Temperature did not affect the nutrient release from NPK fertilizers.
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  • 9
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    Nutrient cycling in agroecosystems 47 (1996), S. 243-250 
    ISSN: 1573-0867
    Keywords: fertilizer value ; nitrogen ; phosphorus ; poultry manure ; urea ; wetland rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Poultry manure applied alone or in combination with urea at different N levels was evaluated as a N source for wetland rice grown in a Fatehpur loamy sand soil. Residual effects were studied on wheat which followed rice every year during the three cropping cycles. In the first year, poultry manure did not perform better than urea but by the third year, when applied in quantities sufficient to supply 120 and 180 kg N ha−1, it produced significantly more rice grain yield than the same rates of N as urea. Poultry manure sustained the grain yield of rice during the three years while the yield decreased with urea. Apparent N recovery by rice decreased from 45 to 28% during 1987 to 1989 in the case of urea, but it remained almost the same (35, 33 and 37%) for poultry manure. Thus, urea N values of poultry manure calculated from yield or N uptake data following two different approaches averaged 80, 112 and 127% in 1987, 1988 and 1989, respectively. Poultry manure and urea applied in 1:1 ratio on N basis produced yields in between the yields from the two sources applied alone. After three cycles of rice-wheat rotation, the organic matter in the soil increased with the amount of manure applied to a plot. Olsen available P increased in soils amended with poultry manure. A residual effect of poultry manure applied to rice to supply 120 or 180 kg N ha−1 was observed in the wheat which followed rice and it was equivalent to 40 kg N ha−1 plus some P applied directly to wheat.
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  • 10
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    Landscape ecology 11 (1996), S. 27-38 
    ISSN: 1572-9761
    Keywords: abandoned channels ; floodplain ; nitrogen ; organic matter ; phosphorous ; potassium ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nature of sediments in abandoned channels is an important component of their development as floodplain wetlands. The texture, organic matter, phosphorous, potassium, and nitrogen content of sediments were determined for abandoned channels along the Iowa and Cedar Rivers near their confluence in Iowa. Differences in the levels of these constituents were examined among categories of three landscape gradients: present connectivity to the river, time since abandonment, and proximity to agricultural land use. Local scale processes of ecological development are seen in the importance of time for increased organic matter and nitrogen. Basin scale processes of sediment transport and deposition are revealed by the importance of connectivity for decreases in these two elements, and by the counter-intuitive findings for nitrogen and especially phosphorous and potassium in relation to agricultural proximity. Location on a floodplain is important for differentiating development, but it cannot be reduced to univariate gradients.
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  • 11
    ISSN: 1572-9761
    Keywords: wetlands ; non-point source pollution ; nitrogen ; watershed ; leaching ; geographic information system ; landscape ; groundwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We developed a spatially-explicit, quantitative Nitrogen Leaching Index to assess the potential for non-point source subsurface nitrogen pollution to wetlands. The index was based on the leaching potential of the watershed soils, the amount of nitrogen available for leaching, and the spatial position of nitrogen sources in the watershed. A raster or cell-based geographic information system (GIS) was used to estimate the necessary data inputs for calculating the index, such as soil hydrologic group, land use/soil type combination, groundwater residence time, and location of septic systems. The Total and Average Watershed Nitrogen Leaching Index (TWNLI and AWNLI) were calculated by summing and averaging, respectively, individual cell contributions over a watershed. Analysis of nine wetland watersheds in central New York state, USA, with mixed forest and agricultural land uses illustrated the use of the index for identifying and ranking wetlands with potential nitrogen pollution. Results showed that the spatial characteristics of a watershed potentially can effect subsurface nitrogen delivery to groundwater-dominated wetlands. The use of an index based on watershed soils, topography, and land use may be useful for assessing potential nitrogen pollution to wetlands at a regional scale.
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  • 12
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    European biophysics journal 24 (1996), S. 293-299 
    ISSN: 1432-1017
    Keywords: Phase transition ; NMR ; DSC ; X-ray diffraction ; Bonnet Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Ternary systems of palmitoyl-oleoyl-phosphatidylcholine (POPC) and the non-ionic surfactant C12EO2 (di-ethylene-oxide-mono-dodecyl-ether) in water have been studied with optical microscopy, NMR, DSC and X-rays from ambient temperatures to 45 °C. Below 29 °C the system is in the lamellar liquid crystalline state. Between 30 and 32 °C it transforms into a cubic Ia3d structure which converts into the cubic Pn3m phase at 39 °C. The transitions are fully reversible. An epitaxial relationship between all three phases was found, which is an elegant and convenient way to rearrange molecules from lamellar bilayers to a network of curved surfaces. The la3d (Q230) to Pn3m (Q224) transition occurs without measurable enthalpy change. This, together with the metric relation of 1.60 between the cubic lattice constants is strong evidence for a Bonnet transformation, where the structural changes occur without change in curvature. The potential significance of the cubic phases as intermediate structures for biological processes, e. g. transport across a bilayer or fusion of membranes, are discussed.
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  • 13
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    Environmental management 20 (1996), S. 523-539 
    ISSN: 1432-1009
    Keywords: Water control ; Floodplain ; Fisheries ; Bangladesh ; Chandpur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Bangladesh is a very flat delta built up by the Ganges—Brahmaputra—Meghna/Barak river systems. Because of its geographical location, floods cause huge destruction of lives and properties almost every year. Water control programs have been undertaken to enhance development through mitigating the threat of disasters. This structural approach to flood hazard has severely affected floodplain fisheries that supply the major share of protein to rural Bangladesh, as exemplified by the Chandpur Irrigation Project. Although the regulated environment of the Chandpur project has become favorable for closed-water cultured fish farming, the natural open-water fishery loss has been substantial. Results from research show that fish yields were better under preproject conditions. Under project conditions per capita fish consumption has dropped significantly, and the price of fish has risen beyond the means of the poor people, so that fish protein in the diet of poor people is gradually declining. Bangladesh is planning to expand water control facilities to the remaining flood-prone areas in the next 15–20 years. This will cause further loss of floodplain fisheries. If prices for closed-water fish remain beyond the buying power of the poor, alternative sources of cheap protein will be required.
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  • 14
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    Journal of thermal analysis and calorimetry 47 (1996), S. 35-49 
    ISSN: 1572-8943
    Keywords: bone cement ; DSC ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bone cements are widely used for the fixation of metallic prostheses in orthopaedics and to form replacements for skull defects in neurosurgery. Acrylic bone cements are based on a mixture of methyl methacrylate (MMA) and a fine powder of polymethyl methacrylate (PMMA). The polymerization of the bone cement occurs in contact with the bone and the prosthesis which act as the boundaries of a bulk polymerization reactor. The kinetic behaviour of the bone cement plays a fundamental role for the final performance of the implant. In this paper, the isothermal and non-isothermal polymerization behaviour of a commercial bone cement is described. A simple phenomenological model, accounting for the autoacceleration ffect, for a diffusion controlled termination mechanism and for the reaction between inhibitor and initiator, is proposed. The reaction kinetics is analysed by DSC. DSC data are used for the determination of the rates of polymerization under isothermal and non-isothermal conditions. The experimental data are processed to calculate the parameters of the proposed phenomenological kinetic model. The analytical and numerical details related to the integration of the model are discussed.
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  • 15
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    Journal of thermal analysis and calorimetry 47 (1996), S. 181-194 
    ISSN: 1572-8943
    Keywords: DSC ; gelatinization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Data obtained by dynamic mechanical analysis and DSC analysis of durum wheat dough are presented and discussed. Doughs with water contents ranging from 45 to 55% (w/w) were subjected to sinusoidal shearing by means of a dynamic mechanical spectrometer (Rheometrics, RFS2) equipped with parallel plate geometry, 0.1 strain amplitude and 1 rad/min frequency. The tests were carried on in temperature sweep mode at a heating rate of 2°C min−1. Wheat samples with water contents in the range between 7.5 and 37.5% and doughs with 37.5% moisture content were mixed for different times and subjected to DSC analysis (Perkin-Elmer, DSC-7) at a heating rate of 20°C min−1. Dynamic mechanical analysis revealed that the relationship between the dynamic properties of the dough and the temperature was modified as the water content of the dough increased and was quite different from that for gluten. A similar response was observed in the course of temperature scans made by means of DSC. These experimental findings suggest that the water-starch interaction in the presence of a protein matrix is affected by the availability of water and that the protein system is a competitor with respect to starch.
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  • 16
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    Journal of thermal analysis and calorimetry 47 (1996), S. 543-557 
    ISSN: 1572-8943
    Keywords: compensation effect ; DSC ; kinetics ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Four computer programs as well as one demo-version for non-linear evaluation of kinetic data in thermal analysis and calorimetry, were presented. The multi-task program TA-kin meets all mathematical requirements for solving the numerical assignments. It is shown that the so-called compensation effect is due to the mathematical structure of the Arrhenius equation. Several applications of TA-kin to a lot of DSC- and TG-measurements and isoperibolic batch experiments as well as adiabatic semi batch experiments realized by precision calorimetry have been discussed.
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  • 17
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    Journal of thermal analysis and calorimetry 47 (1996), S. 685-695 
    ISSN: 1572-8943
    Keywords: DSC ; polymers ; resins ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The paper describes the co-curing studies of ethynyl and ethenyl end-capped imide resins. The effect of composition and chemical structure of ethenyl end-capped resins (nadicimides) on thermal behavior of ethynyl end-capped resins was evaluated using DSC and thermogravimetric analysis. An increase in char yield was observed on co-curing of few resin formulations. A mechanism has been proposed to account for this observation.
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  • 18
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1213-1228 
    ISSN: 1572-8943
    Keywords: cassava starch ; DSC ; starch thermal properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Order-disorder transitions were investigated in native cassava starch at intermediate moisture contents (35 to 60% wt. water), using Differential Scanning Calorimetry (DSC) and dynamic Wide Angle X-ray Diffractometry (WAXS) with a synchrotron radiation source. The gelatinization of granules occurs as a cooperative process, due to constraints induced in crystallites by the amorphous areas. Variations of water content (water volume fraction from 0.28 to 0.86) and heating rate (0.2–10
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  • 19
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1179-1200 
    ISSN: 1572-8943
    Keywords: DSC ; isothermal microcalorimetry ; retrogradation ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the present study, isothermal microcalorimetry was introduced as a tool to investigate properties of starch retrogradation during the first 24 h. The study was made on purified amylose and amylopectin from corn, as well as on native starches, such as wheat, potato, maize, waxy maize and amylomaize, differing in their amylose content. The results were obtained in the form ofP-t traces (thermal powervs. time), and integration of these traces gave a net exothermic enthalpy of reaction, caused by the crystallization of amylose and amylopectin. TheP-t traces reflected the quantities of amylose and amylopectin in the starch studied. Depending on the amylose content and the botanical source of the starch, the rate of crystallization of amylose was high and predominated over that of amylopectin during the first 5–10 h. The contribution from amylose crystallization to the measured exothermic enthalpy was very substantial during this period. After ∼10 h, amylose crystallized at a lower constant rate. During the first 24 h, amylopectin crystallized at a low steady rate. The exothermic enthalpies obtained by the isothermal microcalorimetric investigations during the first 24 h of retrogradation were generally low in relation to the endothermic melting enthalpies observed by differential scanning calorimetry (DSC) measurements after 24 h of storage. The discrepancies in enthalpy values between the two methods are discussed in relation to phase separation and the endothermic effects owing to the decrease in polymer-water interactions when polymer-rich regions in the starch gel separate. Besides the exothermic enthalpies obtained, theP-t traces also made it possible to study the initial gelation properties of amylose from different botanical sources. The present study further demonstrated that isothermal microcalorimetry can provide a possible way to investigate the antistaling effect of certain polar lipids, such as sodium dodecylsulphate (SDS) and 1-monolauroyl-rac-glycerol (GML), when added to starches of different botanical origin. The net exothermic heat of reaction for starch retrogradation during the first 24 h was decreased when GML or SDS was added to the starch gels. The recordedP-t traces also showed how the effect of the added lipid influenced different periods during the first 24 h of starch retrogradation, and that the effect depended mainly on the amylose content, the botanical source of the starch, and the type of lipid used. When GML or SDS was added to waxy maize, the isothermal microcalorimetric studies clearly indicated some interaction between amylopectin and the polar lipids. These results concerning the action of anti-staling agents are further discussed in relation to the helical inclusion complexes formed between amylose-polar lipid and amylopectin-polar lipid.
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  • 20
    ISSN: 1572-8943
    Keywords: cooling/heating rate ; DSC ; fragility parameter ; glass transition temperature ; sorbitol-fructose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The glass transition temperatures of sorbitol and fructose were characterized by four points determined on DSC heating thermograms (onset, mid-point, peak and end-point), plus the limit fictive temperature. The variations of these temperature values, observed as functions of cooling and heating rates, were used to determine the fragility parameter, as defined by Angell [1] to characterize the temperature dependence of the dynamic behavior of glass-forming liquids in the temperature range above the glass transition. The apparent activation energy values, determined for the different temperatures studied, were similar for fructose and sorbitol. These values were compared to data obtained from other techniques, such as mechanical spectroscopy. The variations of the apparent activation values, observed in experiments involving cooling and heating at the same rate, slow cooling followed by rate-heating, or rate-cooling followed by fast heating, were explained by aging effects occurring during the heating step.
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  • 21
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1545-1565 
    ISSN: 1572-8943
    Keywords: cocoa butter ; fat crystallization ; DSC ; fat polymorphism ; fat structure ; fats ; lard ; milk fat ; triacylglycerols ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal behavior of three ural fats (displaying very different composition), cocoa butter (CB)2, lard, and a stearin obtained from anhydrous milk-fat (AMF) fractionation, were studied by both DSC and X-ray diffraction as a function of temperature (XRDT). To perform temperature explorations between −30
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  • 22
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    Journal of thermal analysis and calorimetry 46 (1996), S. 5-14 
    ISSN: 1572-8943
    Keywords: cadmium phenoxyacetate ; complexes ; DSC ; mercury(II) phenoxyacetate ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Solid cadmium and mercury(II) phenoxyacetates were prepared and investigated by DSC and TG techniques. The cadmium salt decomposed in two steps with the loss of 1.5 water molecules at first and the successive formation of CdCO3 as final product. Δdeh H * associated with the loss of one water molecule was compared with the corresponding values obtained for other phenoxyacetates previously studied and the obtained results were discussed. Anhydrous mercury(II) phenoxyacetate gave, on heating, HgCO3 which successively decomposed with the formation of gaseous products and a little amount of solid residue.
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  • 23
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    Journal of thermal analysis and calorimetry 46 (1996), S. 177-186 
    ISSN: 1572-8943
    Keywords: activation energy ; chalcogenide glass ; DSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Results of differential scanning calorimetry (DSC) at different heating rates on Se2Ge0.2Sb0.8 chalcogenide glass are reported and discussed. As the heating rate (α) changed, also the glass transition temperature (T g) and onset temperature of crystallization (T c) changed. As the value of the transition activation energyE t changed, the crystallization fraction (χ), heat flow (Δq and the crystallization peak temperature (T p) also changed. The value of the effective activation energy of crystallizationE c was calculated by means of six different methods. The Se2Ge0.2Sb0.8 chalcogenide glass has two crystallization mechanisms, a one-dimensional and an other surface crystallization growth. The average value ofE t for Se2Ge0.2Sb0.8 is equal to 194.95±3.9 kJ·mol−1 and the average value ofE c is equal to 164±3.3 kJ·mol−1.
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  • 24
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    Journal of thermal analysis and calorimetry 46 (1996), S. 237-243 
    ISSN: 1572-8943
    Keywords: DSC ; DTG ; polyacetylene films ; TMA
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Polyacetylene films irradiated byγ-rays up to 100 MRad were studied by means of TMA, DTG and DSC methods. It is shown that as the irradiation dose increases the concentration of topological branching knots into the polymer chains and theT g values decrease, the total mass loss and the enthalpy of the thermal isomerization reaction also decrease.
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  • 25
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    Journal of thermal analysis and calorimetry 46 (1996), S. 619-626 
    ISSN: 1572-8943
    Keywords: crystallization ; DSC ; filled polypropylene ; nucleation ; structural modification
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of high concentration of BaSO4 as nucleating agent on crystallization of fiber-forming polypropylene was studied by DSC. The work presents experimental and calculated values of melting and crystallization enthalpies of filled polypropylene and the influence on the formation of interface interactions between filler and polymers. These results show minimal interactions of components (BaSO4 and polypropylene) under experimental conditions.
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  • 26
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    Journal of thermal analysis and calorimetry 46 (1996), S. 643-679 
    ISSN: 1572-8943
    Keywords: DDTA ; DSC ; macromolecules
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    Topics: Chemistry and Pharmacology
    Notes: Abstract This review traces the development of thermal analysis over the last 40 years as it was experienced and contributed to by the author. The article touches upon the beginning of calorimetry and thermal analysis of polymers, the development of differential scanning calorimetry (DSC), single run DSC and other special instrumentations, up to the recent addition of modulation to calorimetry. Many new words and phrases have been introduced to the field by the author and his students, leaving a trail of the varied interests one can have over 40 years. It began with “cold crystallization” and most recently the term “oriented, intermediate phase” was coined, creating in-between: “extended chain crystals,” the “irreversible thermodynamics of melting of polymer crystals,” “dynamic differential thermal analysis” (DDTA), “the rule of constant increase ofC p per mobile bead within a molecule at the glass transition temperature,” “superheating of polymer crystals,” “melting kinetics,” “crystallization during polymerization,” the “chain-folding principle, “molecular nucleation,” “rigid amorphous phase,” a “system of classifying molecules,” “macroconformations,” “amorphous defects,” “rules for the entropy of fusion based on molecular shape and flexibility,” “single-molecule single-crystals,” “a system of classifying phases and mesophases,” and “condis phase.”
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  • 27
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    Journal of thermal analysis and calorimetry 46 (1996), S. 795-808 
    ISSN: 1572-8943
    Keywords: DSC ; kinetics ; liquid crystalline polymer ; optical transmittance ; polycarbosilane ; side-chain mesogen ; transition parameters
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    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper is concerned with an analysis of the thermodynamics and kinetics of mesophase formation by cooling from the isotropic state of side-chain liquid crystalline polycarbosilanes containing spacers in the range from 3 to 11 CH2-groups. The polymers are characterized by their thermotropic behaviour as far as temperature, enthalpy and entropy of the transitions are concerned. The kinetics was followed by optical and calorimetric methods. Longer spacer length leads to more perfect ordering in the mesophase, higher isotropization temperatures, and lower glass transition temperatures. The Avrami and Ozawa formalism to describe the transition kinetics to the mesophase from the isotropic state cannot be interpreted as the nucleation and growth mechanism known from crystallization.
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  • 28
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1201-1212 
    ISSN: 1572-8943
    Keywords: aging ; amylopectin ; DSC ; gels ; glass transition ; recrystallization ; retrogradation ; rice starch ; sugars
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal characterization of gelatinized binary rice starch-water and ternary starch-sugar-water gels before and after aging was carried out using differential scanning calorimetry. The glass transition temperature of the maximally freeze-concentrated solution (T′g) in both fresh and aged gels was observed to decrease progressively with increasing sugar concentration. Aging of the gels generally shiftedT′g to higher temperatures, but had little or no effect on the ice melting peak temperature (T m). The presence of various sugars could either accelerate or retard starch (amylopectin) recrystallization, depending on the type and concentration of sugar, as well as on starch/water ratio. A hypothesis based on the dual antiplasticizing-plasticizing effects of sugars was postulated to explain the observed effects. Of the sugars studied, xylose and fructose appeared to display exceptional retardative and accelerative effects, respectively, on retrogradation.
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  • 29
    ISSN: 1572-8943
    Keywords: DSC ; gelatinisation ; potato starch
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Gelatinisation temperatures as a function of moisture content were determined for potato starch. The native starch was then hydrothermally treated at a temperature 3% (Kelvin degrees) below the gelatinisation peak temperature and at moisture levels varying from 20 to 67% (by weight). Gelatinisation temperatures, temperature ranges and enthalpy values were affected for all treated samples. However, two sample populations could be distinguished: those samples treated under ‘limited’ moisture conditions and other samples treated in the presence of ‘extragranular’ moisture. A two-step hydrothermal treatment further increased the gelatinisation temperature, but the effect of the second step was small in comparison to that of the first.
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  • 30
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1299-1314 
    ISSN: 1572-8943
    Keywords: baked goods ; cookies ; crackers ; DSC ; pretzels ; starch
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    Topics: Chemistry and Pharmacology
    Notes: Abstract We describe an application of DSC as an analytical ‘fingerprinting’ method that has been used to characterize the thermal properties of wheat starch in low-moisture, wheat-flour-based baked products, including cookies, crackers, and pretzels. This use of DSC has enabled us to relate starch thermal properties, on the one hand, to starch structure, and on the other hand, to starch functionality, in terms of baking performance and finished-product quality.
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  • 31
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1339-1360 
    ISSN: 1572-8943
    Keywords: bread crumb ; bread dough ; DSC ; hydrocolloid ; mechanical properties ; pentosans ; protein
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The effects of hydrocolloids (guar and locust bean gums), soluble pentosans, and whey proteins on staling of bread crumb were investigated by means of DSC, rheometry, and image analyis. One current hypothesis, that these ingredients would behave as “water binders” and, at least the former two, as anti-staling agents, was indeed confirmed, although this action might be indirect. All the samples considered showed an exothermic DSC peak preceding the endotherm of the amylopectin fusion. According to a previous work, this signal was attributed to a water-dependent cross-linking process that would involve next-neighbouring polymer chains. To check the effect produced by molecular modifications that were expected to increase the water uptake of these ingredients, doughs containing added succinylated pentosans and whey proteins, and a polycarboxylate polymer, PEMULEN TR-1, were examined. These modifications enhanced starch retrogradation and yielded a firmer crumb. It was tentatively concluded that some direct interaction between these modified molecules and the crumb polymers might have taken place. In line with the food polymer science approach, the use of Time-Temperature-Transformation (TTT) diagrams is also discussed.
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  • 32
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1513-1525 
    ISSN: 1572-8943
    Keywords: Β-lactoglobulin ; DSC ; protein modification ; thermal properties
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal properties of Β-lactoglobulin (Β-LG) were studied by differential scanning calorimetry (DSC) under different medium conditions.pH, neutral salts, protein perturbants, and polyols all affected the DSC characteristics of Β-LG. Acylation with fatty acids also changed the thermal properties, particularly peak width at half-height. The results suggest that the structural stability of Β-LG is controlled by non-covalent forces, particularly electrostatic and hydrophobic interactions. Disulfide bonds did not contribute to the thermal response of Β-LG. Fatty N-acyl-amino acids caused marked increases in thermal stability and decreases in denaturation enthalpy, and additional peaks were observed in the presence of some palmitoyl derivatives.
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  • 33
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    Journal of thermal analysis and calorimetry 46 (1996), S. 347-352 
    ISSN: 1572-8943
    Keywords: DSC ; optical densities ; thermal stability ; three-component interpolymer complexes
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    Topics: Chemistry and Pharmacology
    Notes: Abstract A new type of three-component interpolymer complexes (3IPCM) formed by two similarly charged polyelectrolytes and an oppositely charged low molar mass compound was studied by DSC, NMR and X-ray methods. The low molar mass monobasic compounds in these complexes act as mediators. This type of complexes differs from earlier-obtained 3IPCM, which contained a dibasic low molar mass mediator. The present 3IPCM were obtained from two polymers (polyacrylic acid and sodium polyphosphate) and bases such as 4-vinylpyridine and 2-methyl-5-vinylpyridine.
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  • 34
    ISSN: 1572-8943
    Keywords: cure kinetics ; DSC ; epoxy resins ; gelation
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    Notes: Abstract By employing differential scanning calorimetry (DSC) we have studied the kinetic of the cure reaction for a system containing a diglycidyl ether of bisphenol A (DGEBA) and 1,3-bisaminomethylcyclohexane (1,3-BAC) as a curing agent, using an isothermal approach over the temperature range of 60–110°C. We have determined the reached conversions at several cure temperatures and the reaction rates. The results showed that this cure reaction is autocatalytic. The experimental data were compared with the autocatalytic model proposed by Kamal, which includes two rate constants and two reaction orders. This model gives a good description of cure kinetics up to vitrification point. The activation energies for these rate constants were 44-57 kJ mol−1. From the gel time measurements the value obtained for the overall activation energy was 49.5 kJ mol−1.
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  • 35
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    Journal of thermal analysis and calorimetry 46 (1996), S. 465-470 
    ISSN: 1572-8943
    Keywords: ABS polymer ; DSC ; lifetime estimation ; thermooxidation
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The service life of ABS polymer, stabilized by 2-(3,5-di-tert-butyl-4-hydroxyanilino)-4,6-bis(octylthio)-1,3,5-triazine and containing 50% of a modifying rubber component, was estimated from oxidative induction times measured by DSC in isothermal mode in the temperature interval 140–170°C. The lifetime of ABS powder at the actual temperature of drying was predicted by linear extrapolation according to Arrhenius. However, the extrapolated value was much longer than the real lifetime determined from the long-term oven aging tests at 70 and 90°C, simulating the industrial drying process. The effect of changes in the apparent activation energy of oxidation due to antioxidant consumption during polymer aging is discussed.
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  • 36
    ISSN: 1572-8943
    Keywords: complexes ; DSC ; guest-host interactions ; X-ray
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The stoichiometry of thermal decomposition and the thermochemistry were studied for [NiL4(NCS)2] (I) as a host complex, and for its clathrates of type [NiL4(NCS)2]·2G, where L=4-ethylpyridine and guest molecule G=1-methylnaphthalene in clathrate (II), 1-chloronaphthalene in (III) or 1-bromonaphthalene in (IV). For I, the loss of volatile components proceeds in three steps (−2L, −L, −L); the first steps for II–IV also involve the release of G (−2G, −2L). DSC and X-ray powder measurements indicated a phase transition in the host lattice, and allowed differentiation of the escape of G and L molecules. The enthalpy changes give the following sequence of thermodynamic stability for the studied chlathrates: I〉II〉III.
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  • 37
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    Journal of thermal analysis and calorimetry 46 (1996), S. 753-771 
    ISSN: 1572-8943
    Keywords: crystal-crystal transitions ; crystal forms ; DMA ; DSC ; Nylon M5T ; X-ray
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Poly(2-methylpentamethylene terephthalamide) (Nylon M5T) is a new high temperature aromatic polyamide developed by Hoechst Celanese. In this paper thermal properties of Nylon M5T chips, as well as as-spun and drawn fibers were studied by DSC, DMA, hot stage microscopy and WAXS.T g of the fully amorphous Nylon M5T is 143°C when measured by DSC;T g increases with crystallinity to 151°C. The temperature dependence of the solid and melt specific heat capacities has also been determined. The heat capacity increase at the glass transition of the amorphous polymer is 103.9 J °C−1 mol−1.T g by DMA for the as-spun fiber is 155°C, for a drawn fiber is 180°C. Three secondary transitions were observed by DMA in addition to the glass transition. These correspond to a local mode relaxation of the methylene groups at −120°C, onset of rotation of the amide-groups at −65°C and the onset of the rotation of the phenylenegroups (at 63°C). The crystallinity of Nylon M5T strongly depends on the rate of cooling from the melt. The isothermal crystallization data are melt temperature dependent: two-dimensional crystallization takes place when the samples are crystallized from higher melt temperatures, and this phase changes into a spherulitic structure during cooling to room temperature. Spherulitic crystallization occurs when lower melt temperatures are used. This polymer has three crystal forms as indicated by DSC, DMA and WAXS data. The crystal to crystal transitions are clearly visible when amorphous samples are heated in the DSC, or the DMA curves of as-spun fibers are recorded. It is experimentally shown that a considerable melting of the lower temperature crystal forms takes place during the crystal to crystal transitions. The equilibrium melting point as measured by the Hoffman-Weeks method, has been determined to be 339°C.
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  • 38
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    Journal of thermal analysis and calorimetry 46 (1996), S. 871-878 
    ISSN: 1572-8943
    Keywords: DSC ; melting point ; polyethylene ; Raman-active longitudinal acoustical mode ; semi-crystalline polymers
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    Topics: Chemistry and Pharmacology
    Notes: Abstract This is a study for criteria to judge the melting point of semi-crystalline polymers from the DSC endotherm for polymer melting. Beyond standard indium DSC melting results an evaluation has been made on a series of polyethylenes for which crystal sizes were measured and predicted from Raman LAM analysis. The results confirm the conclusion of Prof. Wunderlich that the DSC content of melting is the proper basis of reporting melting points.
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  • 39
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    Journal of thermal analysis and calorimetry 46 (1996), S. 893-903 
    ISSN: 1572-8943
    Keywords: cold crystallization ; DSC ; heat capacity ; modulated temperature DSC ; poly(ethylene terephtalate)
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The modulated temperature differential scanning calorimetric method (MT-DSC) yields three temperature dependent signals, an underlying heat capacity curve from the underlying heat flow rate (corresponding to the conventional DSC signal), and a complex heat capacity curve with a real part (storage heat capacity) and an imaginary part (loss heat capacity). These curves have been measured in the cold crystallization region for poly(ethylene terephtalate) with a modified Perkin-Elmer DSC-7. The underlying curve shows the well known large exothermic crystallization peak. The storage heat capacity shows a step change which reproduces the change in heat capacity during crystallization. This curve may be used as baseline, to separate the crystallization heat flow rate from the underlying heat flow rate curve. The loss heat capacity curve exhibits a small exothermic peak at the temperature of the step change of the storage curve. It could be caused by changes of the molecular mobility during crystallization.
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  • 40
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    Journal of thermal analysis and calorimetry 46 (1996), S. 1251-1258 
    ISSN: 1572-8943
    Keywords: boiling points ; DSC ; TGA ; vapour pressure
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    Topics: Chemistry and Pharmacology
    Notes: Abstract A TGA instrument has been adapted for rapid measurement of boiling points and vapour pressure at temperatures from ambient up to 400°C and pressures from ambient down to 20 mm Hg. Samples were contained in sealed holders having a laser-drilled aperture. Several organic liquids in the 100 to 300 gMW range showed good agreement with reference vapour pressure data. Sample mass, heating rate, and use of inert diluents were important variables affecting accuracy of vapour pressure measurements.
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  • 41
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    Journal of thermal analysis and calorimetry 47 (1996), S. 957-973 
    ISSN: 1572-8943
    Keywords: DSC ; Gibbs energy ; liquid crystalline polyethers
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    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of polyethers have been synthesized from 1-(4-hydroxy-4′-biphenyl)-2-(4-hydroxyphenyl)propane and α, Ω-dibromoalkanes having different numbers of methylene units [TPPs]. Both odd- and even-numbered TPPs [TPP(n=odd)s and TPP(n=even)s) exhibit multiple transitions during cooling and heating and they show little supercooling dependence, indicating close-to-equilibrium nature of these transitions. Combining the structural characterization obtainedvia wide angle X-ray diffraction powder and fiber patterns at different temperatures and the morphological observations from microscopy techniques, not only the nematic liquid crystalline phase but also highly ordered smecticF, smectic crystalG andH phases have been identified. The phase diagrams for both TPP(n=odd)s and TPP(n=even)s have been constructed [1–3]. Thermodynamic properties (enthalpy and entropy changes) during these transitions are studied based on differential scanning calorimetry experiments. The contributions of the mesogenic groups and methylene units to each ordering process can be separated and they indicate the characteristics of these processes thereby providing estimations of the transition types.
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  • 42
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1743-1753 
    ISSN: 1572-8943
    Keywords: DSC ; HSM ; oxazepam ; PEG 4000 ; solid dispersion
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    Topics: Chemistry and Pharmacology
    Notes: Abstract A thermal study using DSC and Hot Stage Microscopy (HSM) was carried out to investigate the interaction in solid state of the binary system PEG 4000 — oxazepam, and to establish their phase diagram. The eutectic composition, which melting occurs at lower temperature as compared with the pure components, has been determined. The results obtained by DSC and HSM have indicated that PEG 4000 — oxazepam mixtures displays no obvious incompatibilities, and that the system shows a typical eutectic behaviour. However because of the closeness of the melting of PEG 4000 to the eutectic temperature, it was difficult to determine precisely the eutectic composition and temperature on the basis of DSC measurements alone. The use of heats of fusion corresponding to physical mixtures allowed an estimation of the eutectic composition at 6% w/w oxazepam. Additional information of temperature (57.6
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  • 43
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1755-1758 
    ISSN: 1572-8943
    Keywords: combustion calorimetry ; DSC ; sulphamide type compounds
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Two compounds of sulphamide type:p-amino-benzene sulphonamide (I) and 3,4-dimethylisoxazol 5-sulphanylamide (II) were studied by combustion calorimetry and by differential scanning calorimetry (DSC). The enthalpies in solid state at 298,15 K of combustion, δc H m o (I)=-2788,5±1,6 kJ mol−1, δc H m o (II)=-5036±3,8 kJ mol−1 and of formation, δf H m o (I)=-458,3±1,6 kJ mol−1, δfH m o (II)=-180,1±3,8 kJ mol−1 were determined. The thermal effects concerning the melting and phase transition of this compounds were also measured.
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    Journal of thermal analysis and calorimetry 47 (1996), S. 1787-1803 
    ISSN: 1572-8943
    Keywords: DSC ; food components ; food microbiology ; food quality
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Differential scanning calorimetry (DSC) is the most widely used thermal analytical technique in food research and it has a great utility in quality assurance of food. Proteins are the most studied food components by thermal analysis including studies on conformation changes of food proteins as affected by various environmental factors, thermal denaturation of tissue proteins, food enzymes and enzyme preparations for the food industry, as well as effects of various additives on their thermal properties. Freezing-induced denaturation of food proteins and the effect of cryoprotectants are also monitored by DSC. Polymer characterization based on DSC of polysaccharides, gelatinization behaviour of starches and interaction of starch with other food components can be determined, and phase transitions during baking processes can be studied by DSC. Studies on crystallization and melting behaviour of fats observed by DSC indicate changes in lipid composition or help characterizing products. Thermal oxidative decomposition of edible oils examined by DSC can be used for predicting oil stability. Using DSC in the freezing range has a great potential for measuring and modelling frozen food thermal properties, and to estimate the state of water in foods and food ingredients. Research in food microbiology utilizes DSC in better understanding thermoadaptive mechanisms or heat killing of food-borne microorganisms. Isothermic microcalorimetric techniques provide informative data regarding microbial growth and microbial metabolism.
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  • 45
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    Keywords: DSC ; pharmaceutical technology ; polymer
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    Topics: Chemistry and Pharmacology
    Notes: Abstract In the present study, the effect of the molecular weight and thermal treatments on commercial polyethylene glycols (PEG) samples used in the pharmaceutical processing technology, has been analyzed using DSC and HSM. The molecular weight of these polymers range from 1500 to 200000. Thermal investigations on the melting behavior of original PEG samples (as received from the manufacturer) showed only one single melting DSC endotherm effect before 373 K. This fact was associated to the presence of only one type of polymeric chain. Using standard conditions, PEG samples were solidified from the melt at 373 K, either by flash cooling (using liquid nitrogen and an ice bath) and by slow cooling, soaked and by slow cooling at room temperature. They were further studied by DSC. It was found that after cooling, PEG with molecular weight 1500 and 15000 showed DSC thermograms with a single endothermic peak. However, thermograms for PEG 4000 and 6000 produced a splitted melting endotherm. This fact was attributed to the presence of two types of chains, that are the folded and extended chains. Ageing time influences also the shape of the DSC endothermal effects. It was concluded that the endotherms obtained after heating these PEG indicate that the thermal history determine the structure (extended or folded chain type forms) and the degree of crystallinity, as evidenced by changes in heat of fusion values, melting points and structures after crystallization. The relationships between melting enthalpies and melting points, as deduced from DSC diagrams, with molecular weight of the polymers are also presented.
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  • 46
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    Journal of thermal analysis and calorimetry 46 (1996), S. 1081-1092 
    ISSN: 1572-8943
    Keywords: chemical ionization MS ; constrained dye ; DSC ; dye-amylose inclusion complex ; Tandem MS ; TGA ; Thermal Desorption MS
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal properties of a dye molecule (guest) inside the cavity of a host amylose helix were studied by TGA, DSC, and Thermal Desorption MS. The results show that the degradation temperature of dye shifts to a higher temperature by approximately 20°C.
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  • 47
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    Journal of thermal analysis and calorimetry 46 (1996), S. 1093-1111 
    ISSN: 1572-8943
    Keywords: conformational disorder ; crystal ; DSC ; glass ; glass transition ; heat capacity ; melting transition ; tetra[methyleneoxycarbonyl (2,4,4-trimethyl) pentyl] methane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Quantitative thermal analysis was carried out for tetra[methyleneoxycarbonyl(2,4,4-trimethyl)pentyl]methane. The ester has a glass transition temperature of 219 K and a melting temperature of 304 K. The heat of fusion is 51.3 kJ mol−1, and the increase in heat capacity at the glass transition is 250 J K−1 mol−1. The measured and calculated heat capacities of the solid and liquid states from 130 to 420 K are reported and a discussion of the glass and melting transitions is presented. The computation of the heat capacity made use of the Advanced Thermal Analysis System, ATHAS, using an approximate group-vibration spectrum and a Tarasov treatment of the skeletal vibrations. The experimental and calculated heat capacities of the solid ester were compared over the whole temperature range to detect changes in order and the presence of large-amplitude motion. An addition scheme for heat capacities of this and related esters was developed and used for the extrapolation of the heat capacity of the liquid state for this ester. The liquid heat capacity for the title ester is well represented by 691.1+1.668T [J K−1 mol−1]. A deficit in the entropy and enthalpy of fusion was observed relative to values estimated from empirical addition schemes, but no gradual disordering was noted outside the transition region. The final interpretation of this deficit of conformational entropy needs structure and mobility analysis by solid state13C NMR and X-ray diffraction. These analyses are reported in part II of this investigation.
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  • 48
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    Journal of thermal analysis and calorimetry 46 (1996), S. 1113-1132 
    ISSN: 1572-8943
    Keywords: chiral molecule ; conformational disorder and motion ; crystal ; DSC ; heat capacity ; γ-gauche effect ; glass ; glass transition ; melting transition ; molecular mechanics computations ; tetra[methyleneoxycarbonyl (2,4,4-trimethyl) pentyl] methane ; solid state13C NMR ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The symmetric neopolyol ester tetra[methyleneoxycarbonyl(2,4,4-trirnethyl)pentyl]methane (MOCPM) has been studied by variable-temperature solid-state13C NMR and X-ray powder diffraction and compared to molecular mechanics calculations of the molecular structure. Between melting and glass transition temperatures the material is semicrystalline, consisting of two conformationally and motionally distinguishable phases. The more mobile phase is liquid-like and is, thus attributed to an amorphous phase (≈16%). The branches of the molecules in the crystal exhibit two conformationally distinguishable behaviors. In one, the branches are well ordered (≈56%), in the other, the branches are conformationally disordered (≈28%). Different branches of the same molecule may show different conformational order. This unique character of the rigid phase is the reason for the deficit of the entropy of fusion observed earlier by DSC. In the melt, solid state NMR can identify two bonds that are rotationally immobile, even though the molecules as a whole have liquid-like mobility. This partial rigidity of the branches accounts quantitatively for the observed increase in heat capacity at the glass transition. The reason for this unique behavior of MOCPM, a small molecule, is the existence of one chiral centers in each of the four arms of the molecule. A statistical model assuming that at least two of the chiral centers must fit into the order of the crystal can explain the crystallization behavior and would require 12.5% amorphous phase, 28.1% conformational disorder, and 59.4% crystallinity, close to the observed maximum perfection.
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  • 49
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    Journal of thermal analysis and calorimetry 46 (1996), S. 1177-1189 
    ISSN: 1572-8943
    Keywords: DSC ; mercury porosimetry ; pore size distribution ; porous glass ; thermoporosimetry ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pore size distributions (PSDs) of microporous glass, which were controlled by acid leaching subsequent to phase separation of CaO-Al2O3-B2O3-SiO2 glass, were determined via both mercury porosimetry and thermoporosimetry (thermal porosimetry). As a result, the pore radii, the cumulative pore volumes, and the surface areas determined via thermoporosimetry were in good agreement with those determined via mercury porosimetry. It was revealed that thermoporosimetry could be applied to pore structure analysis for porous materials having pore sizes at least up to 58 nm in radius.
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  • 50
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    Journal of thermal analysis and calorimetry 46 (1996), S. 1339-1347 
    ISSN: 1572-8943
    Keywords: boehmite ; DSC ; gibbsite
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The dehydroxylation of gibbsite into boehmite was investigated by means of DSC analysis under non-isothermal conditions in the temperature range 453–673 K at heating rates from 2.5 to 20.0 K min−1. Mathematical analysis of the experimental DSC curves revealed the mechanism and kinetics of the gibbsite dehydroxylation process. The kinetic curvesα=f(t) andα=f(T) are sigmoidal in shape; their inflection points and the νm point of the curvesν=f(T) andν=f(T) are interrelated and are defined by the concept of a stationary point. The activation energy for the first stage of gibbsite dehydroxylation in the temperature range 453–673 K is 132.92±8.33–142.26±8.33 kJ mol−1.
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  • 51
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    Journal of thermal analysis and calorimetry 46 (1996), S. 1541-1550 
    ISSN: 1572-8943
    Keywords: DSC ; FTIR ; grafting ; IDSC ; kinetic parameters ; polymerization ; TG ; thermodynamic parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal polymerization of pentabromobenzyl (mono)acrylate (PBB-MA) on the surface of the inorganic fillers Mg(OH)2 and CaCO3 was studied. FTIR spectroscopy and extraction of the polymer in bromobenzene show that polypentabromobenzyl acrylate (PBB-PA) was mostly grafted on the surface of Mg(OH)2. Thermal analysis (TG, DSC, isothermal DSC (IDSC)) demonstrated an increase in polymerization starting temperature, and differences in polymerization enthalpy and apparent activation energy when an inorganic filler is added. These differences depend on the chemical composition of the filler used.
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  • 52
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    Journal of thermal analysis and calorimetry 47 (1996), S. 117-121 
    ISSN: 1572-8943
    Keywords: baseline ; DSC ; heat of fusion ; polyethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A technique is proposed for improving the accuracy of the heat of fusion of semicrystalline polymers by DSC. The results of three commercially available instruments are compared.
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  • 53
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    Journal of thermal analysis and calorimetry 47 (1996), S. 195-213 
    ISSN: 1572-8943
    Keywords: DMA ; DSC ; rheological impacts ; thermomechanical properties
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermomechanical properties of bread components can be used to characterize various events that have direct rheological impacts. The objective is to observe changes that occur during staling and toughening of a bread or similar products. In this article, characterization of bread polymers, starch and gluten, were examined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA).
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  • 54
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    Journal of thermal analysis and calorimetry 47 (1996), S. 445-452 
    ISSN: 1572-8943
    Keywords: catalysts ; catalyst activity ; catalyst deactivation ; DSC ; gas reactions ; kinetics
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Gas reactions, catalyzed by solid catalysts, can be measured by DSC. In the experimental set-up an open sample pan with catalyst (powder or pellet) is placed on the sample side of the DSC sensor. The reactive gas mixture flows through the cell and reacts on the catalyst surface. The heat effect, caused by this reaction, results into a DSC signal. The calibration procedure is described for quantitative evaluation of the DSC measurements. For illustration four different reaction systems are discussed.
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  • 55
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    Journal of thermal analysis and calorimetry 47 (1996), S. 503-514 
    ISSN: 1572-8943
    Keywords: cardiac myosin ; DSC ; flexibility of myosin heads ; spin-labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Conventional and saturation transfer electron paramagnetic resonance spectroscopy (EPR and ST EPR) and differential scanning calorimetry (DSC) were used to study the motional dynamics and segmental flexibility of cardiac myosins. Cardiac myosins isolated from bovine and human heart muscle were spin-labelled with isothiocyanate- or maleimide-based probe molecules at the reactive sulfhydryl sites (Cys-697 and Cys-707) of the motor domain. The maleimide probe molecules attached to human cardiac myosin rotated with an effective rotational correlation time of 33 ns which was at least eight times shorter than the rotational correlation time of the same label on skeletal myosin (260 ns). In the presence of MgADP and MgADP plus orthovanadate, flexibility changes in the multisubunit structure of myosins were detected, but this did not lead to changes of the overall rotational property of the myosin heads. Significant difference in the internal flexibility was detected on myosin samples isolated from ischemic tissue, the rotational correlation time decreased to 25 ns. DSC measurements supported the view that addition of nucleotides produced additional loosening in the multisubunit structure of cardiac myosin. It is postulated that there is an intersite communication between the nucleotide binding domain and the 20 kDa subunit where the reactive thiol sites are located.
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  • 56
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    Journal of thermal analysis and calorimetry 47 (1996), S. 765-774 
    ISSN: 1572-8943
    Keywords: calcium aluminates ; cement ; DSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Differential scanning calorimeter (DSC) has been used to study the dehydration characteristics of hydrated calcium aluminates such as CA, CA2 and C12A7 where C and A stand for CaO and Al2O3 respectively. Dehydration of CAH10 and C2AH8 (whereH=H2O) occur ∼ at 160–180°C and 200–280°C respectively. These two phases are unstable and ultimately get transformed to AH3 and C3AH6. Dehydration of AH3 and C3AH6 occur between 290 and 350°C and overlap at lower scanning rate. The activation energy for dehydration of the stable AH3 and C2AH6 phases has been found to be 107.16 and 35.58 kJ mol−1 respectively. The compressive strength of the hydrated calcium aluminates has been determined. The result shows that in the case of CA, almost 90% of ultimate strength has been attained in 1 day whereas in CA2, ultimate strength has been attained in 14 days and in C12A7 in 1 day. DSC results have been correlated with the rate of strength developments.
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  • 57
    ISSN: 1572-8943
    Keywords: crown-ethers (CE) ; 12-C-4 ; 15-C-5 ; DC 18-C-6anti ; DC 18-C-6syn ; DSC ; LiAlH4-CE complexes ; glass-transition ; solvates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal behaviour of complexes [Li+-EC](AlH4)− withEC=12-C-4, 15-C-5, DC 18-C-6 (cis-anti-cis andcis-syn-cis isomers) was investigated by Differential Scanning Calorimetry (DSC). These complexes were prepared as solids from benzene solutions. Pure EC and several solvated species [Li+-EC](AlH4)−·nC6H6 (EC=15-C-5, DC 18-C-6syn) were also studied. DSC has revealed various phenomena. Solid-solid transitions were observed before melting for [Li+-EC](AlH4)− withEC=12-C-4 and 15-C-5. They are probably explained by small molecular modifications strongly dependent on the thermal history of the sample. A glass-transition was found for the pure crown-ether DC 18-C-6anti, the complex [Li+-EC](A1H4)− withEC=DC-18-C-6anti and the two solvates mentioned above.
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  • 58
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    Journal of thermal analysis and calorimetry 47 (1996), S. 887-896 
    ISSN: 1572-8943
    Keywords: compensation temperature ; DSC ; fictive temperature ; poly(ethylene terephthalate) ; thermally stimulated depolarization current
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    Topics: Chemistry and Pharmacology
    Notes: Abstract This work deals with a comparison of data obtained from differential scanning calorimetry (DSC) and thermally stimulated depolarization current (TSDC) investigations. Measurements were performed on various poly(ethylene terephthalate) films: a wholly amorphous, a thermally crystallized and drawn samples. For each specimen, the TSDC complex spectra, resolved into elementary ones, led to the determination of the classical compensation temperature (T c ). The glass transition temperature (T g) and the fictive equilibrium temperature (T f) were determined by means of DSC. It appears thatT c is different fromT g and very close toT f.
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  • 59
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    Journal of thermal analysis and calorimetry 47 (1996), S. 931-939 
    ISSN: 1572-8943
    Keywords: DSC ; isothermal melt crystallization ; kinetic parameters ; Mathematica® ; new kinetic model ; poly(L-lactic acid)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A DSC study was carried out of the isothermal melt crystallization kinetics of poly(L-lactic acid), PLLA, at 110, 115, 120, 125 and 130
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  • 60
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    Plasma chemistry and plasma processing 16 (1996), S. 577-603 
    ISSN: 1572-8986
    Keywords: Cathode erosion ; electrode materials ; argon ; nitrogen ; hydrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Cathode erosion continues to be a problem hindering the widespread application of plasma technology. In this work, cathode erosion was studied on titanium, stainless steel 314, copper-nickel 10% and 30%, and copper 122 for magnetically rotated arcs operating in argon, nitrogen, and argon/hydrogen mixtures at a constant magnetic flux density of 0.1 T Titanium and stainless steel gave very low erosion rates in argon (0.2 and 0.3, μg/C respectively). Cupronickels were shown to be suitable for nitrogen and hydrogen plasmas. The slope of hydrogen solubility versus temperature in the cathode material was found to be important in determining hydrogen plasma erosion characteristics. When the plasma gas has a high solubility in the cathode material, or can react with the cathode, a negative erosion rate may result. When gas solubility in the cathode is low, oxide stability and mode of electron emission may govern the erosion rate. A high gas solubility in the cathode material, as with hydrogen, can result in mechanical erosion due to micro-explosions near the cathode surface.
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  • 61
    ISSN: 1573-2932
    Keywords: atmospheric deposition ; ecosystem ; hydrology ; nitrogen ; sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Information on atmospheric inputs, water chemistry and hydrology were combined to evaluate elemental mass balances and assess temporal changes in elemental transport from 1983 through 1992 for the Arbutus Lake watershed. This watershed is located within a northern hardwood ecosystem at the Huntington Forest within the central Adirondack Mountains of New York (USA). Changes in water chemistry, including increasing NO3 − concentrations (1.1 μmol c , L−1 yr-1), have been detected during this study period. Starting in 1991 hydrological flow has been measured from Arbutus Lake and these measurements were compared with predicted flow using the BROOK2 hydrological simulation model. The model adequately (r2=0.79) simulated flow from this catchment and was used to estimate drainage for earlier periods when direct hydrological measurements were not available. Modeled drainage water losses coupled with estimates of wet and dry atmospheric deposition were used to calculate solute budgets. Export of SO4 2− (831 mol c ha−1 yr−1) from the greater Arbutus Lake watershed exceeded estimates of atmospheric deposition in an adjacent hardwood stand suggesting an additional source of S. These large drainage losses of SO4 2− also contributed to the drainage fluxes of basic cations (Ca2+, Mg2+, K+ and Na+). Most of the atmospheric inputs of inorganic N were retained (average of 74% of wet precipitation and 85% total deposition) in the watershed. There were differences among years (56 to 228 mol ha−1 yr−1) in drainage water losses of N with greatest losses occurring during a warm, wet period (1989–1991).
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  • 62
    ISSN: 1573-2932
    Keywords: Pulp and paper mill sludge ; nitrogen ; DOC ; heavy metals ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Primary sludge, secondary sludge, and wood ash from a pulp and paper mill were combined with sand to create a synthetic topsoil (C:N ratio of 18:1) to restore an abandoned gravel pit. Synthetic topsoil was applied to field microcosms at rates equivalent to 0, 2170, 4341, or 6511 kg N/ha; each was seeded with grass. Fifteen chemical constituents in leachate were measured during two field seasons. Cadmium, Ni and Zn were mobilized rapidly by soil disturbance. Chloride and SO4-S eluted rapidly from the sludge along with Na. Nitrate leached with Ca late in each field season when sludge N-mineralization and nitrification exceeded plant uptake and microbial immobilization. Ammonium elution was negligible. Dissolved organic carbon (DOC) was mobilized by decomposition of organic matter in the sludge, as were Mg and K. Copper eluted with DOC, probably as an organic ligand. Lead and ortho-P were below our detection limits. We concluded that a synthetic topsoil with a 30:1 C:N ratio applied at a rate of 2100-4300 kg N/ha should provide adequate plant nutrition while minimizing water quality hazards.
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  • 63
    ISSN: 1573-5028
    Keywords: ACC synthase ; differential expression ; ethylene ; root-specific expression ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two partial 1-aminocyclopropane-1-carboxylic acid (ACC) synthase cDNA clones (pWAS1, 1089 bp; andpWAS3, 779 bp) were isolated by polymerase chain reaction (PCR) using cDNA to total mRNA purified from etiolated wheat seedlings as template and degenerate oligonucleotides synthesized based on the regions of the ACC synthase amino acid sequence that are highly conserved among different plants. Northern analysis showed that the expression of the corresponding genes are differentially regulated. While the transcripts ofpWAS1 were found in all the tissues of wheat that were tested with a maximum level at the early stages of spike development,pWAS3 mRNA was present almost exclusively in the root. A 5590-bp genomic clone,TA-ACS2, corresponding topWAS3 cDNA has been isolated. TheTA-ACS2 sequence consists of a 589-bp 5′-upstream region, 2743 bp of transcribed region with four exons and three introns and a 3′-downstream region of 2257 bp. Expression inEscherichia coli confirmed the ACC synthase activity of TA-ACS2 polypeptide. Sequence comparisons show that the two wheat ACC synthases are more similar to each other and to the rice ACC synthase,OS-ACS1, at the nucleotide level than at the amino acid level. The amino acid sequence of TA-ACS2 is most similar (66.1% identity) to that of broccoli. The chromosomal location of both wheat ACC synthase genes have been determined by aneuploid analysis.TA-ACS1 is located on the short arm of chromosomes 7A and 7D and on the long arm of chromosome 4A.TA-ACS2 is located on the long arm of homoeologous group 2 chromosomes.
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  • 64
    ISSN: 1573-5028
    Keywords: abscisic acid ; early cysteine-labeled protein ; fluridone ; metallothioneins ; pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A clone for an embryoid-abundant, early cysteine-labeled metallothionein (EcMt) gene has been isolated from a wheat pollen embryoid cDNA library. The transcript of this gene was only expressed in embryogenic microspores, pollen embryoids, and developing zygotic embryos of wheat. Accumulation of the EcMt mRNA showed a direct and positive correlation with an increase of the plant hormone, abscisic acid (ABA) in developing pollen embryoids. Treating cultures with an inhibitor of ABA biosynthesis, fluridone, suppressed not only ABA accumulation but also the appearance of the EcMt gene transcript and the ability of microspores to form embryoids. These results suggest that the EcMt gene may act as a molecular marker for pollen embryogenesis because ABA biosynthesis is accompanied by the increased expression of the EcMt transcript that coincides with the differentiation of pollen embryoids in wheat anther cultures.
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  • 65
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    Plant molecular biology 30 (1996), S. 673-677 
    ISSN: 1573-5028
    Keywords: cDNA sequence ; chymotrypsin inhibitor ; histidine-tag ; protein Z ; serpin ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A full-length clone encoding the wheat (Triticum aestivum L.) serpin WSZ1 was isolated from a cDNA library based on mRNA from immature grain. The 398 amino acid sequence deduced from the cDNA was corroborated by sequencing CNBr peptides of WSZ1 purified from resting grain. WSZ1 belongs to the subfamily of protein Z-type serpins and the amino acid sequence is 70% identical with the barley serpins BSZ4 and BSZx and 27–33% identical with human serpins such as α1-proteinase inhibitor, antithrombin III, and plasminogen activator inhibitor. The cDNA was subcloned in the pET3d expression vector, equipped with a histidine affinity tag at the N-terminus and expressed in Escherichia coli BL(21) DE3 pLysS. Recombinant WSZ1 from the soluble fraction was partially purified on Ni-NTA agarose and MonoQ columns and shown to form SDS-stable complexes with α-chymotrypsin. Southern blots and amino acid sequencing indicated that only few serpins are encoded by wheat, but at least three distinct genes are expressed in the grain. Cleavage experiments on a chymotrypsin column suggested a Gln-Gln reactive site bond not previously observed in inhibitory serpins.
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  • 66
    ISSN: 1573-5028
    Keywords: differential display ; HSP70 gene family ; 3′ non-coding region ; Triticum aestivum
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    Topics: Biology
    Notes: Abstract We have modified the differential display technique to isolate 3′ regions from different members of the wheat HSP70 gene family. An HSP70 gene family-specific degenerate primer was used as a 5′ primer in place of the arbitrary primer used in the original technique. We cloned and sequenced three cDNA fragments that were differentially expressed in heat stressed wheat seedlings. Based on the high similarity between predicted translation products of these three sequences and known members of the HSP70 family from plants, these cDNAs were identified as members of the HSP70 gene family. Two of these members appeared distinct in the 3′ non-coding region with only 48% identity. Therefore differential display could successfully be used to isolate 3′ regions of different members of a multigene family in a relatively short period, even if the members had highly similar protein-coding regions.
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  • 67
    ISSN: 1573-5028
    Keywords: cDNA cloning ; gene expression ; glutamine synthetase ; grapevine ; nitrogen ; Vitis vinifera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grapevine (Vitis vinifera L.) glutamine synthetase (GS) was analysed into two distinct classes of isoforms; one of them was present in both leaf and root tissues while the other one showed leaf specificity. Western blot analysis revealed that grapevine GS consists of three types of polypeptides of distinct size and differential tissue specificity. Two structurally distinct cDNA clones, pGS1;1 and pGS1;2, encoding grapevine GS were isolated from a cell suspension library and characterized. Both clones contained open reading frames encoding for polypeptides of 356 amino acids with a predicted molecular mass of about 39 kDa. Although the coding sequences of pGS1;1 and pGS1;2 were 84% similar, their 5′-and 3′-untranslated sequences showed only 40% similarity. The coding sequences of the two clones and the derived amino acid sequences showed higher homology to cytosolic than to chloroplastic GSs of other higher plants indicating that the cDNAs isolated encode for cytosolic isoforms of grapevine GS. Southern blot analysis suggested the existence of more than two GS genes in the grapevine genome. In northern blots both clones were hybridized to mRNAs of about 1.4 kb that are differentially expressed in the various tissues. Supply of nitrate or ammonium in the cell suspension culture medium, as a sole nitrogen source, resulted in differential response of the pGS1;1-and pGS1;2-related genes.
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  • 68
    ISSN: 1432-2242
    Keywords: Key wordsSuppressor gene ; Powdery mildew resistance ; Gene location ; Triticum aestivum ; Secale cereale ; Monosomic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The chromosomal location of a suppressor for the powdery mildew resistance genes Pm8 and Pm17 was determined by a monosomic set of the wheat cultivar Caribo. This cultivar carries a suppressor gene inhibiting the expression of Pm8 in cv Disponent and of Pm17 in line Helami-105. In disease resistance assessments, monosomic F1 hybrids (2n=41) of Caribo × Disponent and Caribo × Helami-105 lacking chromosome 7D were resistant, whereas monosomic F1 hybrids involving the other 20 chromosomes, as well as disomic F1 hybrids (2n=42) of all cross combinations, were susceptible revealing that the suppressor gene for Pm8 and Pm17 is localized on chromosome 7D. It is suggested that genotypes without the suppressor gene be used for the exploitation of genes Pm8 and Pm17 in enhancing powdery mildew resistance in common wheat.
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  • 69
    ISSN: 1432-2242
    Keywords: Haynaldia villosa ; Triticum aestivum ; C-banding ; Genomic in situ hybridization ; Alien chromosome addition
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    Topics: Biology
    Notes: Abstract Genomic in situ hybridization (GISH) offers a convenient and effective method for cytological detection, but can not determine the identity of the chromosomes involved. We integrated C-banding with GISH to identify Haynaldia villosa chromosomes in a wheat background. All chromosomes of H. villosa showed C-bands, either in telomeric regions or in both telomeric and centromeric regions, which allowed unequivocal identification of each H. villosa chromosome. The seven pairs of H. villosa chromosomes were differentiated as 1–7 according to their characteristic C-bands. Using a sequential C-banding and GISH technique, we have analyzed somatic cells of F3 plants from the amphiploid Triticum aestivum-H. villosa x ‘Yangmai 158’ hybrids. Three plants (94009/5-4,94009/5-8 and 94009/5-9) were shown to contain H. villosa chromosome(s). 94009/5-4 (2n = 45) had three H. villosa chromosomes (2, 3 and 4); 94009/5-8 (2n = 45) possessed one chromosome 4 and a pair of chromosome 5, and 94009/5-9 (2n = 43) was found to have one chromosome 6 of H. villosa. The combination of GISH with C-banding described here provides a direct comparison of the cytological and molecular landmarks. Such a technique is particularly useful for identifying and localizing alien chromatin and DNA sequences in plants.
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  • 70
    ISSN: 1432-2242
    Keywords: Triticum timopheevii ; Triticum aestivum ; Chromosome substitution ; C-banding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Whether the two tetraploid wheat species, the well known Triticum turgidum L. (macaroni wheat, AABB genomes) and the obscure T. timopheevii Zhuk. (AtAtGG), have monophyletic or diphyletic origin from the same or different diploid species presents an interesting evolutionary problem. Moreover, T. timopheevii and its wild form T. araraticum are an important genetic resource for macaroni and bread-wheat improvement. To study these objectives, the substitution and genetic compensation abilities of individual T. timopheevii chromosomes for missing chromosomes of T. aestivum ‘Chinese Spring’ (AABBDD) were analyzed. ‘Chinese Spring’ aneuploids (nullisomic-tetrasomics) were crossed with a T. timopheevii x Aegilops tauschii amphiploid to isolate T. timopheevii chromosomes in a monosomic condition. The F1 hybrids were backcrossed one to four times to Chinese Spring aneuploids without selection for the T. timopheevii chromosome of interest. While spontaneous substitutions involving all At- and G-genome chromosomes were identified, the targeted T. timopheevii chromosome was not always recovered. Lines with spontaneous substitutions from T. timopheevii were chosen for further backcrossing. Six T. timopheevii chromosome substitutions were isolated: 6At (6A), 2G (2B), 3G (3B), 4G (4B), 5G (5B) and 6G (6B). The substitution lines had normal morphology and fertility. The 6At of T. timopheevii was involved in a translocation with chromosome 1G, resulting in the transfer of the group-1 gliadin locus to 6At. Chromosome 2G substituted for 2B at a frequency higher than expected and may carry putative homoeoalleles of gametocidal genes present on group-2 chromosomes of several alien species. Our data indicate a common origin for tetraploid wheat species, but from separate hybridization events because of the presence of a different spectrum of intergenomic translocations.
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  • 71
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    Theoretical and applied genetics 92 (1996), S. 666-672 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Puccinia striiformis ; Diversity ; Competition ; Path analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four club wheat cultivars and three two-component cultivar mixtures, planted at five frequencies, were grown in three environments in both the presence and absence of stripe rust. The effect of stripe rust on wheat yield was through the yield components, with weight of individual seed being the component most affected by rust. In some cases, yield component compensation was indicated by the presence of negative correlations among the yield components. Path analysis of the yield components revealed that components with the highest correlations to yield also had the largest direct effects on yield. Of the yield components, number of heads per unit area exerted the largest direct influence on yield. The direct effects of number of seeds per head and weight of individual seed were similar, although number of seeds per head was more important in the absence of rust than in its presence. The pure stands and mixtures differed considerably with respect to correlation coefficients, but were very similar for direct effects of yield components on yield. Most of these discrepancies were due to opposing indirect effects, which were not evident from correlation coefficients alone.
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  • 72
    ISSN: 1432-2242
    Keywords: Suppressor gene ; Powdery mildew resistance ; Gene location ; Triticum aestivum ; Secale cereale ; Monosomic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromosomal location of a suppressor for the powdery mildew resistance genes Pm8 and Pm17 was determined by a monosomic set of the wheat cultivar Caribo. This cultivar carries a suppressor gene inhibiting the expression of Pm8 in cv Disponent and of Pm17 in line Helami-105. In disease resistance assessments, monosomic F1 hybrids (2n=41) of Caribo x Disponent and Caribo x Helami-105 lacking chromosome 7D were resistant, whereas monosomic F1 hybrids involving the other 20 chromosomes, as well as disomic F1 hybrids (2n=42) of all cross combinations, were susceptible revealing that the suppressor gene for Pm8 and Pm17 is localized on chromosome 7D. It is suggested that genotypes without the suppressor gene be used for the exploitation of genes Pm8 and Pm17 in enhancing powdery mildew resistance in common wheat.
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  • 73
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; HMW glutenin genes ; Unequal crossing-over ; PCR ; Glu-D1 locus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High-molecular-weight (HMW) glutenin subunits are a particular class of wheat endosperm proteins containing a large repetitive domain flanked by two short N- and C-terminal non-repetitive regions. Deletions and insertions within the central repetitive domain has been suggested to be mainly responsible for the length variations observed for this class of proteins. Nucleotide sequence comparison of a number of HMW glutenin genes allowed the identification of small insertions or deletions within the repetitive domain. However, only indirect evidence has been produced which suggests the occurrence of substantial insertions or deletions within this region when a large variation in molecular size is present between different HMW glutenin subunits. This paper represents the first report on the molecular characterization of an unusually large insertion within the repetitive domain of a functional HMW glutenin gene. This gene is located at the Glu-D1 locus of a hexaploid wheat genotype and contains an insertion of 561 base pairs that codes for 187 amino acids corresponding to the repetitive domain of a HMW glutenin subunit encoded at the same locus. The precise location of the insertion has been identified and the molecular processes underlying such mutational events are discussed.
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  • 74
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    Theoretical and applied genetics 93 (1996), S. 1066-1070 
    ISSN: 1432-2242
    Keywords: Amylose synthesis ; Aneuploid ; Granule-bound starch synthase ; Triticum aestivum ; Wx gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amylose synthesis in wheat endosperm is mainly controlled by the granule-bound starch synthase of about 60 kDa, the so-called waxy (Wx) protein. The Wx proteins are the product of the Wx genes at a triplicate set of single-copy homoeoloci located on chromosomes 7A (Wx-A1), 4A (Wx-B1) and 7D (Wx-D1). Using ‘Chinese Spring’ and its aneuploid lines, including nullisomic-tetrasomics, tetrasomics, ditelosomics and deletion stocks, together with single-chromosome substitution lines for these chromosomes, the effects of varying the dosage of whole chromosomes and chromosome arms, as well as the effects of null alleles, upon amylose synthesis were investigated. Nullisomic 4A and the deletion of chromosome segments carrying the Wx-B1 gene reduced the amylose content by more than 3%. A reasonable agreement was found in the substitution lines. This confirms that the absence of the Wx-B1 gene, or else substitution of this gene by its null allele, has the most striking effect on decreasing amylose synthesis. The removal of chromosomes carrying either the Wx-A1 or the Wx-D1 gene reduces the amylose content by less than 2%. A similar reduction was revealed by substitution of these two genes by the null alleles. Double dosages of chromosomes 7A, 4A and 7D did not increase amylose content, while the tetrasomic chromosomes produced more of the respective Wx proteins. This suggests that a certain level of Wx gene activity or of the Wx proteins led to the maximum amount of amylose.
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  • 75
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    Theoretical and applied genetics 93 (1996), S. 1112-1118 
    ISSN: 1432-2242
    Keywords: Genetic map ; RFLP ; RAPD ; Secale cereale ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genetic map of six chromosomes of rye, (all of the rye chromosomes except for 2R), was constructed using 77 RFLP and 12 RAPD markers. The map was developed using an F2 population of 54 plants from a cross between two inbred lines. A rye genomic library was constructed as a source of clones for RFLP mapping. Comparisons were made between the rye map and other rye and wheat maps by including additional probes previously mapped in those species. These comparisons allowed (1) chromosome arm orientation to the linkage groups to be given, (2) the corroboration of several evolutionary translocations between rye chromosomes and homoeologous chromosomes of wheat; (3) an increase in the number of available markers for target regions of rye that show colinearity with wheat. Inconsistencies in the location of markers between the wheat and rye maps were mostly detected by multi-copy probes.
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  • 76
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    Theoretical and applied genetics 93 (1996), S. 1078-1082 
    ISSN: 1432-2242
    Keywords: Allele-specific PCR (AS-PCR) ; Powdery mildew ; Hordeum vulgare ; Triticum aestivum ; Sequence-tagged site (STS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Primers for the polymerase chain reaction (PCR) were tailored to selectively amplify RFLP marker alleles associated with resistance and susceptibility for powdery mildew in cereals. The differentiation between marker alleles for susceptible and resistant genotypes is based on the discrimination of a single nucleotide by using allele-specific oligonucleotides as PCR primers. The PCR assays developed are diagnostic for RFLP alleles at the loci MWG097 in the barley genome and Whs350 in the wheat genome. The first marker locus is closely linked to MlLa resistance in barley, while the latter is linked to Pm2 resistance locus in wheat. PCR analysis of 31 barley and 30 wheat cultivars, with some exceptions, verified the presence or absence of the resistance loci investigated. These rapid PCR-based approaches are proposed as an efficient alternative to conventional procedures for selecting powdery mildew-resistant genotypes in breeding programs.
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  • 77
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    Theoretical and applied genetics 92 (1996), S. 163-169 
    ISSN: 1432-2242
    Keywords: Bread wheat ; Triticum aestivum ; Culture medium ; Embryogenic callus ; Plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-eight bread wheat (Triticum aestivum L.) released cultivars and elite advanced lines were evaluated for their ability to produce embryogenic callus using three different media. Basal N6 medium supplemented with dicamba (E1), MS medium containing 2,4-D (E3) or MS medium containing 2,4-D plus different amino acids (E5) were used for callus initiation and maintenance. Plant regeneration was achieved on basal MS medium with indole-3-acetic acid (IAA) and 6-benzylamino purine (BAP) and rooting on MS with 1-naphthaleneacetic acid (NAA). Percentage regeneration varied widely with both genotype and initiation medium, with values ranging from 2% to 94%. The number of plantlets produced per embryo ranged from 6 to 42. Thirteen genotypes showed at least 50% regeneration after culture on E5 medium; 3 genotypes after culture on E3 initiation medium and 1 after initiation on E1. After four subcultures, over a 16-week period, 41 genotypes (85%) lost their ability to regenerate plants while the remaining 7 lines (15%) retained plant regeneration potential but at reduced levels. E3 medium was found to be the best for maintaining regeneration potential after four subcultures.
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  • 78
    ISSN: 1432-2242
    Keywords: Wheat ; Triticum aestivum ; Triticum peregrinum ; Chromosome addition lines ; RFLPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analyses of RFLPs, isozymes, morphological markers and chromosome pairing were used to isolate 12 Triticum aestivum cv Chinese Spring (genomes A, B, and D)-T. peregrinum (genomes Sv and Uv) disomic chromosome addition lines. The evidence obtained indicates that each of the 12 lines contains an intact pair of T. peregrinum chromosomes. One monosomic addition line, believed to contain an intact 6Sv chromosome, was also isolated. A CS-7Uv chromosome addition line was not obtained. Syntenic relationships in common with the standard Triticeae arrangement were found for five of the seven Sv genome chromosomes. The exceptions were 4Sv and 7Sv. A reciprocal translocation exists between 4S1 and 7S1 in T. longissimum and evidence was obtained that the same translocation exists in T. peregrinum. In contrast, evidence for syntenic relationships in common with the standard Triticeae arrangements were found for only one Uv chromosome of T. peregrinum.; namely, chromosome 2Uv. All other Uv genome chromosomes are involved in at least one translocation, and the same translocations were found in the U genome of T. umbellulatum. Evidence was also obtained indicating that the centromeric regions of 4U and 4Uv are homoeologous to the centromeric regions of Triticeae homoeologous group-6 chromosomes, that the centromeric regions of 6U and 6Uv are homoeologous to the centromeric regions of group-4 chromosomes, and that 4U and 4Uv are more closely related overall to Triticeae homoeologous group-6 chromosomes than they are to group-4 chromosomes.
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  • 79
    ISSN: 1432-2242
    Keywords: Key words  Wheat ; Triticum aestivum ; Triticum peregrinum ; Chromosome addition lines ; RFLPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   Analyses of RFLPs, isozymes, morphological markers and chromosome pairing were used to isolate 12 Triticum aestivum cv Chinese Spring (genomes A, B, and D)-T. peregrinum (genomes Sv and Uv) disomic chromosome addition lines. The evidence obtained indicates that each of the 12 lines contains an intact pair of T. peregrinum chromosomes. One monosomic addition line, believed to contain an intact 6Sv chromosome, was also isolated. A CS-7Uv chromosome addition line was not obtained. Syntenic relationships in common with the standard Triticeae arrangement were found for five of the seven Sv genome chromosomes. The exceptions were 4Sv and 7Sv. A reciprocal translocation exists between 4Sl and 7Sl in T. longissimum and evidence was obtained that the same translocation exists in T. peregrinum. In contrast, evidence for syntenic relationships in common with the standard Triticeae arrangements were found for only one Uv chromosome of T. peregrinum; namely, chromosome 2Uv. All other Uv genome chromosomes are involved in at least one translocation, and the same translocations were found in the U genome of T. umbellulatum. Evidence was also obtained indicating that the centromeric regions of 4U and 4Uv are homoeologous to the centromeric regions of Triticeae homoeologous group-6 chromosomes, that the centromeric regions of 6U and 6Uv are homoeologous to the centromeric regions of group-4 chromosomes, and that 4U and 4Uv are more closely related overall to Triticeae homoeologous group-6 chromosomes than they are to group-4 chromosomes.
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  • 80
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    Theoretical and applied genetics 93 (1996), S. 1078-1082 
    ISSN: 1432-2242
    Keywords: Key words Allele-specific PCR (AS-PCR) ; Powdery mildew ; Hordeum vulgare ; Triticum aestivum ; Sequence-tagged site (STS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Primers for the polymerase chain reaction (PCR) were tailored to selectively amplify RFLP marker alleles associated with resistance and susceptibility for powdery mildew in cereals. The differentiation between marker alleles for susceptible and resistant genotypes is based on the discrimination of a single nucleotide by using allele-specific oligonucleotides as PCR primers. The PCR assays developed are diagnostic for RFLP alleles at the loci MWG097 in the barley genome and Whs350 in the wheat genome. The first marker locus is closely linked to MlLa resistance in barley, while the latter is linked to Pm2 resistance locus in wheat. PCR analysis of 31 barley and 30 wheat cultivars, with some exceptions, verified the presence or absence of the resistance loci investigated. These rapid PCR-based approaches are proposed as an efficient alternative to conventional procedures for selecting powdery mildew-resistant genotypes in breeding programs.
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  • 81
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    Theoretical and applied genetics 93 (1996), S. 1066-1070 
    ISSN: 1432-2242
    Keywords: Key words Amylose synthesis ; Aneuploid ; Granule-bound starch synthase ; Triticum aestivum ; Wx gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amylose synthesis in wheat endosperm is mainly controlled by the granule-bound starch synthase of about 60 kDa, the so-called waxy (Wx) protein. The Wx proteins are the product of the Wx genes at a triplicate set of single-copy homoeoloci located on chromosomes 7A (Wx-A1), 4A (Wx-B1) and 7D (Wx-D1). Using `Chinese Spring' and its aneuploid lines, including nullisomic-tetrasomics, tetrasomics, ditelosomics and deletion stocks, together with single-chromosome substitution lines for these chromosomes, the effects of varying the dosage of whole chromosomes and chromosome arms, as well as the effects of null alleles, upon amylose synthesis were investigated. Nullisomic 4A and the deletion of chromosome segments carrying the Wx-B1 gene reduced the amylose content by more than 3%. A reasonable agreement was found in the substitution lines. This confirms that the absence of the Wx-B1 gene, or else substitution of this gene by its null allele, has the most striking effect on decreasing amylose synthesis. The removal of chromosomes carrying either the Wx-A1 or the Wx-D1 gene reduces the amylose content by less than 2%. A similar reduction was revealed by substitution of these two genes by the null alleles. Double dosages of chromosomes 7A, 4A and 7D did not increase amylose content, while the tetrasomic chromosomes produced more of the respective Wx proteins. This suggests that a certain level of Wx gene activity or of the Wx proteins led to the maximum amount of amylose.
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  • 82
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    Theoretical and applied genetics 93 (1996), S. 1112-1118 
    ISSN: 1432-2242
    Keywords: Key words Genetic map ; RFLP ; RAPD ; Secale cereale ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genetic map of six chromosomes of rye, (all of the rye chromosomes except for 2R), was constructed using 77 RFLP and 12 RAPD markers. The map was developed using an F2 population of 54 plants from a cross between two inbred lines. A rye genomic library was constructed as a source of clones for RFLP mapping. Comparisons were made between the rye map and other rye and wheat maps by including additional probes previously mapped in those species. These comparisons allowed (1) chromosome arm orientation to the linkage groups to be given, (2) the corroboration of several evolutionary translocations between rye chromosomes and homoeologous chromosomes of wheat; (3) an increase in the number of available markers for target regions of rye that show colinearity with wheat. Inconsistencies in the location of markers between the wheat and rye maps were mostly detected by multi-copy probes.
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  • 83
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    Theoretical and applied genetics 93 (1996), S. 1054-1060 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Rye ; Secale cereale ; 1BL.1RS translocation ; 1AL.1RS translocation ; Gliadin, Electrophoresis ; Erysiphe graminis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A suppressor of resistance to powdery mildew conferred by Pm8 showed complete association with the presence of a storage-protein marker resolved by electrophoresis on SDS-PAGE gels. This marker was identified as the product of the gliadin allele Gli-A1a. The mildewresponse phenotypes of wheats possessing the 1BL.1RS translocation were completely predictable from electrophoretograms. The suppressor, designated SuPm8, was located on chromosome 1AS. It was specific in its suppression of Pm8, and did not affect the rye-derived resistance phenotypes of wheat lines with Pm17, also located in 1RS, or of lines with Pm7.
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  • 84
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    Russian chemical bulletin 45 (1996), S. 794-796 
    ISSN: 1573-9171
    Keywords: nitrogen ; methane ; ethane ; propane ; combined adsorption ; zeolite NaX ; selectivity coefficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Adsorption of N2, CH4, C2H6, C3H8, and their mixture on zeolite NaX was studied by the volumetric method under static conditions at 278 K in the pressure range from 0.1 to 0.8 MPa. Compressibility factors were calculated in order to take into account the nonideal character of the gas phase. Adsorption isotherms of individual gases and partial isotherms were obtained. The adsorption properties of gases in the adsorption of a mixture and its components were compared. The selectivity coefficient of adsorption of propane in the N2-CH4-C2H6-C3H8-NaX system was calculated, and its dependence on the total pressure was determined.
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  • 85
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    Journal of plant research 109 (1996), S. 375-380 
    ISSN: 1618-0860
    Keywords: Gravitropism ; Growth direction ; Seminal roots ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seminal root system of wheat (Triticum aestivum L.) is composed of the primary seminal root, the first pair of seminal roots, and the second pair of seminal roots, which are known to grow in different directions. The direction of root growth, which can be expressed by ϑ (the angle between the root and the plumb line) and φ (the angle between the root and a vertical plane including the primary seminal root), was studied with special attention to the latter. It was measured on seedlings grown in a small hemispherical soil-filled mesh basket. There were varietal differences in the φ of the first pair of roots (φf) and in the φ of the second pair of roots (φs). (φf) and (φs) were significantly correlated. The mean distance (MD), a measure to evaluate the efficiency of root spacing, was correlated with the difference between (φf) and (φs). Neither experimentally applied low soil water potential nor the excision of the primary seminal root affected φ. When the grain was sown vertically with the tip of the embryo pointing downwards, it was found that the growth movement into a direction different from the plumb line and (φs) was greatly modified. it is suggested that certain internal mechanisms, possibly involving gravitropic reactions, are operating to control the direction of root growth. The significance of root growth direction at the seedling stage is discussed.
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  • 86
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    Protoplasma 193 (1996), S. 204-212 
    ISSN: 1615-6102
    Keywords: Golgi bodies ; Mitochondria ; Plastids ; Symmetrical divisions ; Protophloem sieve elements ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protophloem sieve elements (PSEs) in roots of wheat (Triticum aestivum L.) are arranged in single vertical files. The number of PSEs within the files increases by symmetrical divisions, which take place after the completion of asymmetrical (formative) divisions and before the initiation of differentiation. The divisions are preceded by well defined pre-prophase bands (PPB) of microtubules, which surround the nucleus in an equatorial position. In the cytoplasmic region between the nuclear surface and the PPB, perinuclear and endoplasmic microtubules were observed. The perinuclear microtubules are considered as part of the developing spindle, while the endoplasmic ones interlink the perinuclear microtubules with the PPB. Dividing cells do not show any signs of incipient differentiation. The first and most reliable indication of a commencing differentiation is provided by the sieve-element plastids that begin to accumulate dense crystalloid inclusions in the very young PSEs. In mature PSEs plastids contain two kinds of crystalloid inclusions, dense and thin, in a translucent stroma. Depending on the plastid-inclusions criterion it was shown that: (a) the PSEs of a given root do not initiate differentiation at exactly the same stage, (b) the developmental sequence extends to a span of 7–9 actively differentiating PSEs arranged in a single vertical file, and (c) each PSE needs about 16–21 h to pass through the whole developmental sequence. In the last two differentiating PSEs of a file, mitochondria were found to be enveloped by single cisternae of ER. The association is temporary as it is lost in the first PSEs with an autolysed lumen. During differentiation, Golgi bodies were abundant and active in producing vesicles involved in cell wall development. Golgi vesicles were also found among the microtubules of the PPB, but no local thickening was observed. Golgi bodies disorganize in the last stages of autolysis and disappear in mature sieve elements.
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  • 87
    ISSN: 1610-7403
    Keywords: calcium ; mineral distribution ; nitrogen ; potassium ; xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The chemical compositions of xylem saps ofCryptomeria japonica D. Don andPinus densiflora Sieb. et Zucc. were studied. One-year-old seedlings of these species were transplanted into hydroponics in the middle of June. Some seedlings were retained in the nursery. Two nitrogen sources, ammonium and nitrate nitrogen, were applied separately. The samplings of xylem saps were made at the end of July. Saps were collected from both roots and tops of the seedlings using a pressure chamber. InC. japonica, the fact that the translocation form of nitrogen from the roots to shoots mainly was citrulline was confirmed. The result ofP. densiflora in this study showed that glutamine was the predominant compound of nitrogen translocation. Total nitrogen ofP. densiflora had a large value in the series of ammonium. Glutamine increased in the ammonium series of both species. Nitrate nitrogen was found in whole samples ofC. japonica, and was not found inP. densiflora. As the result of cations in the saps, monovalent cations were rich inP. densiflora, and divalent cation concentrations were greater inC. japonica. The idea that the great oxygen requirement ofP. densiflora produces the negative charge gives an explanation of the great retention of divalent cations in the roots. The idea that the mineral distribution indicates root activity related to its negative charge production also is considered a possibility.
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  • 88
    ISSN: 1573-5125
    Keywords: Eutrophication ; nutrients ; phosphorus ; nitrogen ; chlorophyll-a ; primary production ; secondary production ; Mytilus edulis ; river Rhine ; Wadden Sea ; North Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From 1955 to the mid 1980s the loads of both nitrogen and phosphorus from the river Rhine to the Dutch coastal area, the Wadden Sea included, increased. Since 1985 the phosphorus loads has decreased significantly, while the nitrogen load remained about the same. Annual primary production in the western Dutch Wadden Sea has increased fromc. 40 g C m−2 (1950) to 150 (mid 1960s) and over 500 g C m−2 (1986). The biomass of macrozoobenthos has more than doubled since 1970. Simultaneously, the meat yield of cultured blue mussels (Mytilus edulis), has increased since the 1960s. Previously, it was indicated that the increase in primary production of the phytoplankton over the period 1950 to 1986 was stimulated by the load of dissolved inorganic phosphate from Lake IJssel, a reservoir supplied by Rhine water. Since 1990, however, primary production has been higher than was expected from decreased phosphate loads from Lake IJssel. It is argued that this lack of response may have been caused by increased concentrations of dissolved inorganic phosphate at sea originating from increased inflow from a.o. the Strait of Dover, which compensate for the decrease in phosphate from the rivers, possibly in combination with a significant improvement of the light conditions of the water in the Wadden Sea.
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  • 89
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    Journal of applied phycology 8 (1996), S. 389-396 
    ISSN: 1573-5176
    Keywords: Nitzschia inconspicua ; diatoms ; lipids ; fatty acids ; eicosapentaenoic acid ; silicate ; nitrogen ; carbon source
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nitrate and silicate levels, and carbon source on growth, biochemical composition and fatty acid composition ofNitzschia inconspicua were investigated using batch cultures. Within the range of silicate levels supplied (8.8–176 μM), no marked variations in growth trend, biochemical composition or fatty acid composition were shown. Biomass at stationary phase, ranging from 64–66 mg ash-free dry weight (AFDW) L−1, and specific growth rate (μ) based on chlorophylla (0.41–0.50 d−1) of the cultures grown within 0.3–3.0 mM NaNO3 were not significantly different. Cultures supplemented with glucose (0.1 % w/v), acetate (0.1 % w/v) or 5% CO2 attained higher biomass (85, 85, 97 mg AFDW L−1) than the control which was grown in synthetic seawater and agitated by magnetic stirring. Cells grown at 〈3.0 mM NaNO3 contained higher carbohydrate contents (14.8–21.5% AFDW) than those grown at 3.0 mM (4.0% AFDW). Lipid content increased at the expense of proteins in cells aerated with 5% CO2. The dominant fatty acids, 16:0 and 16:1, ranged from 35.7–45.0% and 36.4–45.4% total fatty acids (TFA), respectively, while the relative proportions of 20:4 (n-6) and 20:5 (n-3) ranged from 1.7–5.4% and 3.4–5.9% TFA respectively. Cultures aerated with 5% CO2 attained the highest biomass (97 mg AFDW L−1) and yield of 20:5 (n-3) (0.34 mg L−1).
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  • 90
    ISSN: 1573-5117
    Keywords: river ; hyporheic ; dissolved organic carbon ; nitrogen ; phosphorus ; silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Solute, nutrient and bacterial inputs to the River Rhône from the interstitial habitat of a gravel bar and the floodplain aquifer were investigated during an artificial drought. Eight springs were investigated: four groundwater-fed springs in the floodplain, located at the bottom of the bank; and four interstitial-fed springs located at the downstream end of a gravel bar. During this period, the inflows of groundwater to the river represented an average input of 0.77 mg l−1 of nitrogen (of which 93.3% were nitrates), 0.0187 mg l−1 of total phosphorus (of which 42.2% was orthophosphate), 3.56 mg l−1 of silica, 2.315 ± 0.703 mg l−1 of dissolved organic carbon (DOC, of which 47% was biodegradable) and 7.3 × 104 ± 3.7 × 104 bacteria per ml (of which 8.8% were active). Silica, DOC, biodegradable DOC, and bacteria concentrations displayed temporal variations during the study, which seem to be linked to the biological activity of the groundwater biofilm. There was a strong heterogeneity between the two types of groundwater that flow to the river: concentrations of calcium and alkalinity were higher in bank springs than in gravel bars springs. In these latters, sulfate, sodium, nitrogen, phosphorus were significantly higher.
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  • 91
    ISSN: 1573-5117
    Keywords: Sediment ; nitrogen ; phosphorus ; regeneration ; iron availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During 1994 net sediment-water fluxes of oxygen, ammonium and inorganic phosphorus as well as sediment profiles of organic matter, nitrogen, phosphorus and iron were determined in three shallow eutrophic environments. Investigations were conducted monthly from March to December at five stations in the Sacca di Goro (Po River Delta, Italy). In the late summer, samples were collected from a single site in the Prévost lagoon (French Mediterranean coast) and three stations in the Bassin d'Arcachon (French Atlantic coast). In the Sacca di Goro, water-sediment exchanges of O2, NH 4 + and PO 4 3− were estimated by means of core incubation in the dark. Benthic fluxes for the French lagoons were in part determined experimentally using benthic chambers and in part from the literature. In general in the Sacca di Goro the highest oxygen uptake and nutrient release rates were found at the central sites, affected by macroalgal growth. At the sampling site adjacent to the freshwater inlet, sediment-water exchanges were principally influenced by tidal activity. In terms of organic matter and nutrient levels, sediments from the Sacca di Goro and from the Prévost lagoon, both colonised by the floating macroalga Ulva rigida C. Agardh, were similar. Sediments from the inner sheltered site in the Bassin d'Arcachon, invaded by the rooted macrophyte Ruppia cirrhosa (Pet.) Grande, showed the highest total N and P content (363 ± 157 µmol N cm−3 and 15 ± 2 µmol P cm−3 as average values in the top 10 cm of sediment), but were low in pore water ammonium and orthophosphate probably due to the high sequestering capacity of the system and/or efficient coupling between bacterial nutrient regeneration and assimilation by the plant roots. In addition the outer tidal stations in the Bassin d'Arcachon, invaded by rooted macrophytes, were low in pore water nutrients. A different trend was evident in the Prévost lagoon where the concentrations of exchangeable inorganic phosphorus and ammonium were appreciable (0.28 ± 0.07 µmol P cm−3 and 2.4 ± 1.4 µmol N cm−3 as average values in the top 10 cm of sediment). High amounts of dissolved organic nitrogen were found in the pore water at all the sites investigated showing the key role of the organic nitrogen in the recycling of nitrogen in these systems. The hypothesis that iron is a key factor in controlling phosphorus release is discussed since the Sacca di Goro, which is subject to dystrophic crises, is richer in iron than the Bassin d'Arcachon, which is a more buffered system.
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  • 92
    ISSN: 1573-5117
    Keywords: Nanakita River Estuary ; isotope ratio ; carbon ; nitrogen ; deposit-feeding polychaetes ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two types of deposit-feeding polychaetes, Neanthes japonica and Notomastus sp., and their surrounding sediments were collected from the Nanakita River Estuary and a small brackish lagoon (Gamõ Lagoon) in northeastern Japan. The samples were examined using stable isotope analysis to assess the site specific feeding mode of the animals and their trophic status. N. japonica is a surface deposit-feeder and Notomastus sp. is a subsurface deposit-feeder. In the estuary, the sedimentary δ 5N tended to become isotopically heavier from the upper estuary (2.0 ∼ 3.9‰) to the river mouth (4.3 ∼ 6.2‰), while sedimentary organic δ 13C constant value (−26.8 ∼ −24.4, average −25.6‰) throughout the river estuary. The δ 13C values of N. japonica were similar to those of the surrounding sediment in the upper estuary, whereas in the lower estuary, N. japonica had a heavier δ 13C value than the surrounding sediment. The δ 13C and dg 15N values indicated that the carbon, but not the nitrogen, of N. japonica was derived from upland plants in the upper estuary. In the lower estuary, a significant fraction of carbon of N. japonica was derived from phytoplankton. Notomastus sp. exhibited heavier δ 13C values than the surrounding surface sediment throughout the estuary and had heavier δ 13C values than N. japonica in the same location. These results suggest selective utilization of sedimentary carbon by those animals following bacterial processing and subsequent fractionation. The difference in δ 15N between sedimentary organics and corresponding polychaetes was 5 ± 1‰ and rather higher than 3.4 ± 1.1‰ expected for normal trophic effects in other animals.
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  • 93
    ISSN: 1573-5117
    Keywords: Ulva rigida ; growth rates ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth of the seaweed Ulva rigida C. Agardh was investigated in relation to biomass densities, internal nutrient pools and external nutrient supply. Research was carried out from 23 March to 5 July 1994 in the Sacca di Goro (Po Delta, Northern Italy), whose south-eastern part was covered by extensive mats of Ulva rigida. Two types of field experiments were conducted by incubating Ulva thalli inside large cages. In the first experiment, beginning on 23 March, 100 g of wet thalli were placed into the cages, allowed to grow for two weeks, then collected and replaced. This procedure was repeated 8 times over the study period. In the second experiment, Ulva thalli were left inside the cages and collected at selected time intervals (14, 27, 41, 64 and 76 days) in order to simulate the effects of increased density on growth and nutrient storage. We recorded specific growth rates (NGR) ranging from 0.025 to 0.081 d−1 for a period up to two months in the repeated short-term experiments performed at relatively low initial algal densities (300–500 g AFDW m−3). These NGR resulted significantly related to dissolved inorganic nitrogen (DIN) in the water column. Tissue concentrations of total Kjeldahl nitrogen (TN) were almost constant, while extractable nitrate decreased in a similar manner to DIN in the water column. Total phosphorus showed considerable variation, probably linked to pulsed freshwater inflow. In the long-term incubation experiment, NGR of Ulva was inversely related to density. Internal concentrations of both total P and TN reached maximum values after one month; thereafter P concentration remained almost constant, while TN decreased below 2% w/w (by dry weight). The TN decrease was also accompanied by an abrupt decrease in nitrate tissue concentration. The biomass incubated over the two month period suffered a progressive N limitation as shown by a decreasing NY ratio (49.4 to 14.6). The reciprocal control of Ulva against biogeochemical environment and viceversa is a key factor in explaining both resource competition and successional stages in primary producer communities dominated by Ulva. However, when the biomass exceeds a critical threshold level, approximately 1 kg AFDW m−3, the macroalgal community switches from active production to rapid decomposition, probably as a result of selfshading, biomass density and development of anaerobic conditions within the macroalgal beds.
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  • 94
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    Hydrobiologia 334 (1996), S. 169-183 
    ISSN: 1573-5117
    Keywords: Oligochaete ; eutrophication ; large-scale experiment ; ditch ; phosphorus ; nitrogen ; oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eight experimental ditch mesocosms were used to study the effect of eutrophication over four years. The experimental ditches had a sand or clay bottom. The ditches were treated with additions of phosphorus, phosphorus and nitrogen, or without additions (controls). Oligochaetes were sampled by deploying trays with substratum for colonization over twenty weeks. Both the important variables phosphorus, nitrogen and oxygen as well as the oligochaete species and numbers are presented. The effects of nutrient additions on phosphorus, nitrogen and oxygen concentrations were described together with changes in oligochaete species composition and numbers. The results were further analyzed by redundancy analysis (RDA). In the clay-lined ditches nutrient addition coincided with fluctuation in oxygen concentration. The higher the nutrient addition levels the longer the period of oxygen depletion became. During oxygen depletion the number of oligochaetes was strongly reduced or even became zero. The low nutrient status of the sandy bed in the sand-lined ditches slowed down the rate of colonization. Only a few tubificids were collected. Eutrophication effects were only observed at the highest nutrient addition level. Considerable variation is attributed to stochastic factors in the sand-lined ditches. Whether oligochaete species were present was related to the length of the colonization period. The substratum composition and food together with oxygen regime decided whether they become more or less abundant in ditches. Large-scale mesocosm experiments require time to develop. Only after the first colonization period variables of species presences and abundances can be employed to detect changes associated with eutrophication. Oligochaetes can be used to measure colonization as well as eutrophication processes.
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  • 95
    ISSN: 1573-5117
    Keywords: nitrogen ; phosphorus ; chlorophyll ; organic matter ; mountain lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Concentrations of total phosphorus (TP), inorganic and organic nitrogen, organic matter, and chlorophyll-a were studied in ten mountain lakes at various stages of acidification, trophy, and type of watershed during each July and October from 1987 to 1990. Concentrations of TP and total organic matter were higher in July than in October. Concentrations of NH44 +-N decreased and NO3 −-N increased from July to October. The relative composition of total nitrogen (TN) and its concentration were strongly dependent on the type of watershed: the lowest TN concentrations were observed in lakes with forested watersheds, increasing above the timberline and reaching maximum values in acidified lakes with rocky watersheds. In the pool of TN, nitrate was most important in lakes above the timberline (70–86% of TN), and organic nitrogen in forest lakes (〉 90% of TN). Lakes with rocky watersheds were characterized by high ratios of TN:TP (〉 250 by mass). The concentration of chlorophyll-a varied widely, from 0.01 to 22.6 µg l−1, without any consistent change between July and October, and were P limited.
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  • 96
    ISSN: 1573-5117
    Keywords: air pollution ; deposition ; sulphur ; nitrogen ; base cations ; throughfall ; Leningrad Region ; Scots pine ; soil water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper presents initial results of a joint Finnish-Russian investigation (1991–1996) of air pollutant deposition in Scots pine (Pinus sylvestris Linné) stands of Karelian Isthmus (north-western Leningrad Region, Russia) and south-eastern Finland. Bulk precipitation and canopy throughfall analyses revealed relatively high sulphur and nitrogen loads in the Karelian Isthmus and in the southern part of south-eastern Finland. The deposition load decreased gradually northwards, the highest levels of S and N deposition in the vicinity of St. Petersburg being two to three times higher than the values considered to be background level in Finland. Besides the acidifying elements, a high calcium deposition was detected in the Karelian Isthmus and in the southern part of south-eastern Finland. The high load of calcium, which probably emanates from oil shale burning in NE Estonia, alleviates the acidifying effect of sulphur and nitrogen deposition.
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  • 97
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    Hydrobiologia 322 (1996), S. 241-248 
    ISSN: 1573-5117
    Keywords: water chemistry ; phosphorus ; nitrogen ; intercalibration ; Lake Ladoga ; large lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As part of the Russian-Finnish research studies on Lake Ladoga, joint expeditions were organized in 1992 and 1993. Water samples were collected for intercalibration of chemical analysis methods and to monitor the chemical quality of the lake water. In August of 1992 water samples were taken from northern Lake Ladoga for intercalibration of Russian and Finnish analysis methods. In August 1993 water samples were collected from 23 sampling stations in all parts of the lake; some of these were also used for intercalibration purposes. The oxygen, colour and CODMn results were at the same level in the intercalibration. In 1993, the Ptot results obtained were acceptable. In Ntot, Fe and Mn analysis there seemed to be systematic and random errors between some results. The Secchi depth ranged from 1.5 m to 3.3 m. The average concentrations for the total phosphorus ranged from 15 µg 1−1 to 29 µg 1−1. The total nitrogen values were from 620 µg 1−1 to 690 µg 1−1. The N:P ratio varied from 24 to 40. The concentration of phosphorus indicated mesotrophic or even eutrophic conditions in the lake. Phosphorus seemed to be the limiting nutrient to bacteria and algae.
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  • 98
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    Hydrobiologia 323 (1996), S. 1-8 
    ISSN: 1573-5117
    Keywords: nitrogen ; water chemistry methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied a recently described method for the determination of total nitrogen in natural waters involving sample oxidation with persulfate and subsequent determination of nitrate-nitrogen with second derivative spectroscopy and compared it to the USEPA approved method involving the sum of nitrate-nitrogen and Kjeldahl-nitrogen as measured with an automated analyzer. The overall objective was to determine if the two methods gave the same estimates of total nitrogen and if the detection limits, precision and accuracy of the new method were as good as those of the USEPA method. The new method was used to make measurements on replicated blanks, standards and lake water samples covering a range of concentrations. We also collaborated with certified laboratories to make comparative measurements on 5 standards and 21 lake water samples that were run by us with the new method and by them with the USEPA method. The new method had an instrument detection limit of 0.07 mg 1−1, and the standard deviation of 20 sets of lake water samples averaged 0.03 mg 1−1. The new method gave concentrations equivalent to those found with the USEPA method, was more sensitive, and had a higher degree of precision. We concluded that the new method is suitable as a substitute for the USEPA method. We also found that the addition of acid to lake water samples stored under refrigeration was not necessary to preserve them for later determinations of nitrate-nitrogen and total nitrogen and that freezing was an effective means of sample preservation for 90 days.
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  • 99
    ISSN: 1573-5117
    Keywords: Leaf decomposition ; polyphenols ; nitrogen ; microbial colonization ; Eucalyptus globulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaf decomposition of the exotic evergreen Eucalyptus globulus (eucalyptus), and three native deciduous tree species, Alnus glutinosa (alder), Castanea sativa (chestnut) and Quercus faginea (oak), was compared in a second order stream in Central Portugal. Changes in dry weight, nitrogen and polyphenolic compounds and microbial colonization were periodically assessed for three months. Negative exponential curves fit the leaf weight loss with time for all leaf species. Mass loss rate was in the order alder (K = 0.0161) 〉 chestnut (K = 0.0079) 〉 eucalyptus (K = 0.0068) 〉 oak (K = 0.0037). Microbial colonization followed the same pattern as breakdown rates. Evidence of fungal colonization was observed in alder after 3 days in the stream, whereas it took 21 days in oak leaves to have fungal colonization. Fungal diversity was leaf species-dependent and increased with time. In all cases, percent nitrogen per unit leaf weight increased, at least, at the initial stages of decay while soluble polyphenolics (expressed as percentage per unit leaf weight) decreased rapidly in the first month of leaves immersion. Intrinsic factors such as nitrogen and polyphenolic content may explain differences in leaf decomposition. The possible incorporation of eucalyptus litter into secondary production in a reasonable time span is suggested, although community balance and structure might be affected by differences in allochthonous patterns determined by eucalyptus monocultures.
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  • 100
    ISSN: 1573-5117
    Keywords: biofilter ; nitrogen ; Sparus ; Ulvia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ulva rigida was cultivated in 7501 tanks at different densities with direct and continuous inflow (at 2, 4, 8 and 12 volumes d−1) of the effluents from a commercial marine fishpond (40 metric tonnes, Tm, of Sparus aurata, water exchange rate of 16 m3 Tm−1) in order to assess the maximum and optimum dissolved inorganic nitrogen (DIN) uptake rate and the annual stability of the ‘Ulva tank biofiltering system’. Maximum yields (40 g DW m−2 d−1) were obtained at a density of 2.5 g FW 1−1 and at a DIN inflow rate of 1.7 g DIN m−2 d−1. Maximum DIN uptake rates were obtained during summer (2.2 g DIN M−2 d−1), and minimum in winter (1.1 g DIN m−2 d−1) with a yearly average DIN uptake rate of 1.77 g DIN m−2 d−1 At yearly average DIN removal efficiency (2.0 g DIN m−2 d−1, if winter period is excluded), 153 m2 of Ulva tank surface would be needed to recover 100% of the DIN produced by 1 Tm of fish.
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