摘要:

The history of production and application of the stable nitrogen isotope15N in Germany is mainly part of the history of the former Institute of Stable Isotopes, later a part of the Central Institute of Isotope and Radiation Research (Zentralinstitut für Isotopen-und Strahlenforschung) in Leipzig. In 1956, after a relatively large fractionation during isotopic exchange in the system NO/HNO3was reported by SPINDEL and TAYLOR, the construction of an isotope enrichment plant was planned and started work in 1958 on a laboratory scale. The prodution of15N-labelled material in the institute started in 1960, followed in 1968 by the start of a separation plant in Wolfen as a branch of industrial fertilizer production. The economy was optimized by feeding back the15N decreased efflux to the fertilizer production line.

ISSN:1025-6016    

DOI:10.1080/10256019608036288

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The precursor N-(diphenylmethylene) glycinyl camphor sultam has been specifically labelled by nitrogen-15 or carbon-13 starting from either NH4Cl, K213CO3or13CH3NH2or labelled glycine. Akylation of these different labelled precursors by corresponding electrophiles yielded the following labelled amino acids: Leu, Phe, Ala, Val, Ser, Asn, Gln, Asp, Trp and Cys.

ISSN:1025-6016    

DOI:10.1080/10256019608036289

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Reduction of perrhenate with stannous chloride at an excess of sodium gluconate in aqueous solution results in formation of rhenium(V) gluconate. The reaction proceeds slowly compared to that of pertechnetate. Aqueous solutions of rhenium(V) gluconate can be prepared down to a concentration level of at least 10−4mol·1−1within two hours. The usefulness of rhenium(V) gluconate to serve as a precursor for preparation of oxorhenium(V) complexes as potential radiotherapeutic agents is revealed by subsequent ligand exchange reactions carried out with mercaptoacetyldiglycine, 3-thiapentane-dithiol-1,5/butanethiol and with 2-aminobenzenethiol.

ISSN:1025-6016    

DOI:10.1080/10256019608036290

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The temperature dependence of the carbon-13 kinetic isotope effect (13C KIE) in the decarbonylation of concentrated formic acid solutions of NaCl and of metaphosphoric acid reagent has been determined in the temperature interval 50–110°C and compared with the13C KIE observed in the decarbonylation of pure liquid formic acid. The (k12/k13) values lay in the range 1.058–1.047, expected assuming that the C‒O vibration is lost in the course of activation of formic acid molecules leading to decarbonylation. Metaphosphoric acid reagent present in liquid formic acid at saturation concentrations eliminates all side “minor” processes of physical and chemical nature which caused the slight decrease of the experimental13C kinetic fractionation observed in the course of decarbonylation of pure formic acid from the expected values of13C KIE. Sodium chloride is a less effective breaker of the structure of liquid formic acid than the metaphosphoric acid reagent.

ISSN:1025-6016    

DOI:10.1080/10256019608036291

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The responses of plant growth and carbon isotope discrimination (Δ) to elevated atmospheric CO2concentrations for several crop species (lettuce:Lactuca sativaL.; corn:Zea maysL. var. P3540; wheat:Triticum aestivumL. var Haruyutaka; and soybean:Glycine max(L). Merr. var. Kitamusume) were investigated. Shoot relative growth rate was used to indicate plant growth, and δ13C value of leaf materials in corn (C4 species) was used to calculate Δ for C3 species. Plant growth was stimulated by enriched CO2, while Δ remained almost constant as CO2concentration changed. Δ showed interspecific difference, and the plant species of larger Δ had larger relative growth rates. Relative growth rates of the plants of larger Δ were stimulated by CO2enrichment more than those of the plants of smaller Δ. We propose that plant Δ could be a possible parameter to assess the interspecific difference of plant response to the increasing atmospheric CO2concentrations.

ISSN:1025-6016    

DOI:10.1080/10256019608036292

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Tree-ring δ13C of shoots in two deciduous tree species (Acer rufinerveandClerodendrum trichotomum) at the cool-temperate forest in Japan showed similar trends with time for four years. The variation of tree-ring δ13C positively correlated with the total solar radiation during the growing season, although it did not always correlate with other climatic parameters. Tree-ring δ13C of a tree-core from 1982 to 1993 inA. rufinervealso correlated strongly with the total solar radiation. We conclude that solar radiation most probably affected the tree-ring δ13C in this moist cool temperate forest, because increasing solar radiation can causeCi(intercellular CO2partial pressure) to decrease, consequently increasing δ13C.

ISSN:1025-6016    

DOI:10.1080/10256019608036293

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this study vessel cultures of spruce seedlings were grown with increased amounts of S, Al and Ca applied to soil. Growth development, mineral distribution and stable carbon isotope ratios were measured in plants after the first growing season. Increased sulphate additions to soil are characterized by reduced growth and lower δ13C-values, but take no effects on mineral composition of the seedlings. δ13C-values of plants rose for 0,4%‰ with higher additions of aluminium into soil. Injured roots suggest water deficits that can explain the shift towards higher δ13C-values. CaCO3increases the pH of the soil and causes up to 0,6‰ higher δ13C-values of the plants. Furthermore the addition of CaCO3effects the balance and relations of nutrient composition (Ca, Mg, K). All observed variations in δ13C occur in needles, shoot axis, and in extracted cellulose in common. Changed soil conditions correspond with reactions of the plants in growth, mineral distribution and δ13C.

ISSN:1025-6016    

DOI:10.1080/10256019608036294

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

15N-Labelled phosphoryl triamide (PTA) was synthesized. Experiments withLolium multiflorumplants in vegetation pots have shown that there are important differences between urea and PTA treatments. At high N rates, uptake of N by plants increased in both treatments and N uptake from the soil reserve decreased. The coefficient of N utilization by plants was higher in the urea than in the PTA treatments. However, at the highest N rate, the coefficient of N utilization by plants was higher in the PTA than in the urea treatment. A strong negative correlation was found between the rates applied and the decrease of N content in the soil reserve.

ISSN:1025-6016    

DOI:10.1080/10256019608036295

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Bahareya Oasis is one of the five big oasis located in the Western Desert of Egypt. Seven water samples were collected from the study area. The isotopic composition reflects the paleo-meteoric continental origin of these waters. Deuterium and oxygen-18 results indicate that the groundwaters were recharged under cooler climatic conditions much lower than that of the present day Saharian climate. Salinity values range from 170 mg/l to 338 mg/l. The change in chemical water type from NaCl in El-Gedida area to MgSO4in El-Bawiti area reflects environmental impact through leaching of saline soils and infiltration of agricultural drainage water containing dissolved sulphate salts. The groundwater quality in the area is found to be suitable for agricultural uses.

ISSN:1025-6016    

DOI:10.1080/10256019608036296

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

For the measurement of deuterium content in natural waters, a rapid and precise analytical technique has been developed for the quantitative conversion of water to hydrogen with manganese as reducing agent. It was found that 8μl of water, 0.8 g of Mn, and a reaction time of 40 minutes at 520°C are the optimal conditions for the conversion reaction. Each sample is reduced individually in a high vacuum reaction vessel with a Teflon stopcock. A set of six samples can be prepared at one time. Analyses of standard water samples gave a reproducibility of ±1%(1[sgrave]).

ISSN:1025-6016    

DOI:10.1080/10256019608036297

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor