Changes in chemical nature of soil organic carbon in Vertisols under wheat in south-eastern Queensland

Soil Research ◽  
2001 ◽  
Vol 39 (2) ◽  
pp. 343 ◽  
Author(s):  
J. O. Skjemstad ◽  
R. C. Dalal ◽  
L. J. Janik ◽  
J. A. McGowan
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Plant Material ◽  
Turnover Rate ◽  
High Energy ◽  
Resistant Plant ◽  
Microbial Decomposition ◽  
Organic C ◽  
The Impact ◽  
C Nmr

The impact of cropping and cultivation (up to 50 years) on the nature and pool structure of organic C in two different soil types was investigated using a combination of physical and chemical fractionations and solid-state 13 C NMR spectroscopy. NMR spectroscopy revealed that aryl C contributed significantly to the organic C in the Waco soil (Pellustert) but not in the Langlands-Logie soil (Chromustert). The aryl C content of both soils was largely preserved despite the significant decrease in total organic C, following cultivation, although other organic forms appeared to rapidly decline at similar rates to one another. High energy UV photo-oxidation along with solid-state 13 C NMR spectroscopy demonstrated that the aryl C was mainly charcoal (char) in the <53 mm fraction of the soils which appeared to be highly resistant to microbial decomposition. Char C content of the Waco soil remained near 6.0 g C/kg soil and near 2.0 g C/kg soil for the Langlands-Logie soil. This char was evident to a depth of at least 30 cm in both soils. Fractionation yielded 4 organic C fractions: particulate organic C, humic C, char C, and physically protected C. By equating these fractions to the resistant plant material (particulate organic C), humic pool (humic C), and inert pool (char C) of the RothC soil C turnover model and comparing a number of simulations with measured fractions, we showed that the inert pool equated well with the measured char C. The measured particulate organic C fraction was of an appropriate size to represent the resistant plant material pool of the model but appeared to have a much slower turnover rate. Similarly, the measured humic pool was of a similar size to that required by the model but was more labile (faster turnover rate) than that used in the RothC model. This may be due to a combination of the labile proteinaceous nature of this pool and its lower than expected protection by physical association with the smectitic clay matrix.

Imidazole-containing Bispidine Ligands: Synthesis, Structure and Cu(II) Complexation

2011 ◽  
Vol 66 (7) ◽  
pp. 721-728 ◽  
Author(s):  
Martin Walther ◽  
Madlen Matterna ◽  
Stefanie Juran ◽  
Silke Fähnemann ◽  
Holger Stephan ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Enol Form ◽  
Trans Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Impact ◽  
Configurational Isomerism

The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) derivatives with benzimidazole and imidazole donor groups at the N-3 position of the bispidine skeleton and their copper(II) complexes are reported. The impact of the hetaryl substituents on the configurational isomerism of piperidones and their corresponding bispidones has been studied by NMR spectroscopy, revealing the exclusive appearance in the enol form for the piperidones in solution and the trans-configuration regarding the two pyridyl substituents, as well as the sole formation of the unsymmetric exo-endo isomers for the corresponding bispidones. Thus, the bispidones are preorganized ligands for building pentacoordinated complexes, confirmed by the preparation and characterization of the corresponding Cu(II) complexes. Of the di-pyridyl piperidones with benzimidazole and imidazole substituents, and of the Cu(II) complex of the benzimidazole-containing bispidone, crystals have become available for the analysis by X-ray diffraction, showing that the piperidones form the enol tautomers also in the solid state.

Neue Untersuchung über Inhaltsstoffe der Kreuzdornrinde, IV [1] Die Hauptanthraglykoside der Rinde von Rhamnus catharticus L.: Emodin-8-O-β-gentiobiosid, -glukosid und -primverosid / A New Investigation on the Com position of Rhamni cathartici Cortex, IV [1] The Main Anthraglycosides of the Stem Bark of Rhamnus catharticus L.: Emodin-8-0-/β-gentiobioside, -glucoside and -primveroside

1983 ◽  
Vol 38 (3-4) ◽  
pp. 170-178 ◽  
Author(s):  
Hans-W. Rauwald
Keyword(s):  
Nmr Spectroscopy ◽  
Plant Material ◽  
Chemical Shifts ◽  
Stem Bark ◽  
New Method ◽  
Countercurrent Chromatography ◽  
Anthraquinone Glycosides ◽  
Anthraquinone Derivatives ◽  
First Time ◽  
C Nmr

From the stem bark of Rhamnus catharticus L. (purging buckthorn) the three main anthraquinone glycosides have been isolated by the new method of droplet-countercurrent-chromatography. Their structures were spectroscopically identified as em odin-8-O-β-gentiobioside, -glucoside and -primveroside. From these the primveroside is a new substance, the gentiobioside has been found for the second time in plant material. The structures were confirmed by 13C NMR spectroscopy for the first time in O-glycosides of emodin type. Especially the differences in 13C chemical shifts of the free resp. acetylated aglycones and glycosides are useful parameters for determining the position of O-glycosylation in the 1,8-dihydroxy-anthraquinone derivatives

Importance of charred organic matter in Black Chernozem soils of Saskatchewan

2001 ◽  
Vol 81 (3) ◽  
pp. 285-297 ◽  
Author(s):  
E V Ponomarenko ◽  
D W Anderson
Keyword(s):  
Organic Matter ◽  
High Energy ◽  
Humus Formation ◽  
Organic C ◽  
Particle Size Fractions ◽  
Chernozem Soils ◽  
And Storage ◽  
Uv Oxidation ◽  
Products Of Incomplete Combustion ◽  
C Nmr

A combination of both conventional and novel techniques, such as micromorphology, scanning electron microscopy, and high energy ultraviolet photo-oxidation, have been applied to estimate the proportion of charred organic C in Black Chernozem soils in Saskatchewan. Char was represented by products of incomplete combustion of both arboreal and herbaceous vegetation. Char was found in all particle size fractions of A horizons of Black soils. Char was represented by a variety of forms, from fresh and angular, to rounded and clay-coated particles in the silt fraction. It is likely that the surface area and ability to adsorb clay vary with the size and nature of char particles. Sand-sized char includes particles with various surface properties and adsorptive ability. Generally, younger and lighter char with hydrophobic properties appears to be in the clay-sized fractions, whereas the silt contains heavier char particles coated with clay or containing clay in pores. Ultrasound, used to disperse soils, may fracture larger particles to finer sizes. The proportion of organic C in soils and fractions that is resistant to UV-oxidation was as high as 60%, which, based on published guidelines, indicates a very substantial char component in Black soils. CPMAS 13C NMR spectra indicate a strong aromatic peak at 130 ppm, also consistent with the presence of char. Results indicate that char particles as fine as silt size are present in significant amounts in Black soils, suggesting that char is an important component, and indicating the need for a new concept of humus formation and storage in Black soils. Key words: Char, carbon flows, carbon pool, UV-oxidation, fire, soil organic matter

Alkylaluminum, -gallium, -magnesium, and -zinc monophenolates with bulky substituents

2018 ◽  
Vol 73 (11) ◽  
pp. 943-951 ◽  
Author(s):  
Clint E. Price ◽  
Ana B. Dantas ◽  
Douglas R. Powell ◽  
Rudolf J. Wehmschulte
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Structure Data ◽  
Crystal Structure Data ◽  
The Other ◽  
Zinc Compounds ◽  
C Nmr

AbstractThe bulky phenols 2,6-Ad2C6H3OH (Ad=adamantyl), A, (2,6-Ph2CH)2-4-Me-C6H2OH, B, and (2,6-Tol2CH)2-4-iPr-C6H2OH, C, react with one equivalent of Et3M (M=Al, Ga), Bu2Mg and Et2Zn to afford well-defined mono-phenolate complexes (ArOMRn)m. The aluminum and gallium phenolates derived from the very bulky phenol A are likely monomeric in the solid state. The other compounds are dimeric with bridging phenolates. Crystal structures of compounds with phenols B and C display the dimeric M2O2 cores of the phenolates and illustrate some deviations for the magnesium and zinc compounds. The former possesses stabilizing Mg···C contacts with one of the flanking arene groups of the phenolate substituent, and the latter may be viewed as an intermediate between a symmetric dimer and two monomers. All compounds were characterized by 1H and 13C NMR spectroscopy, and their solution spectra are in agreement with the crystal structure data.

scholarly journals Real-time hyperpolarized 13C magnetic resonance detects increased pyruvate oxidation in pyruvate dehydrogenase kinase 2/4–double knockout mouse livers

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Gaurav Sharma ◽  
Cheng-Yang Wu ◽  
R. Max Wynn ◽  
Wenjun Gui ◽  
Craig R. Malloy ◽  
...  
Keyword(s):  
Steady State ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Real Time ◽  
Pyruvate Dehydrogenase ◽  
Double Knockout ◽  
Tissue Extracts ◽  
Isotopomer Analysis ◽  
The Impact ◽  
C Nmr

Abstract The pyruvate dehydrogenase complex (PDH) critically regulates carbohydrate metabolism. Phosphorylation of PDH by one of the pyruvate dehydrogenase kinases 1–4 (PDK1–4) decreases the flux of carbohydrates into the TCA cycle. Inhibition of PDKs increases oxidative metabolism of carbohydrates, so targeting PDKs has emerged as an important therapeutic approach to manage various metabolic diseases. Therefore, it is highly desirable to begin to establish imaging tools for noninvasive measurements of PDH flux in rodent models. In this study, we used hyperpolarized (HP) 13C-magnetic resonance spectroscopy to study the impact of a PDK2/PDK4 double knockout (DKO) on pyruvate metabolism in perfused livers from lean and diet-induced obese (DIO) mice and validated the HP observations with high-resolution 13C-nuclear magnetic resonance (NMR) spectroscopy of tissue extracts and steady-state isotopomer analyses. We observed that PDK-deficient livers produce more HP-bicarbonate from HP-[1-13C]pyruvate than age-matched control livers. A steady-state 13C-NMR isotopomer analysis of tissue extracts confirmed that flux rates through PDH, as well as pyruvate carboxylase and pyruvate cycling activities, are significantly higher in PDK-deficient livers. Immunoblotting experiments confirmed that HP-bicarbonate production from HP-[1-13C]pyruvate parallels decreased phosphorylation of the PDH E1α subunit (pE1α) in liver tissue. Our findings indicate that combining real-time hyperpolarized 13C NMR spectroscopy and 13C isotopomer analysis provides quantitative insights into intermediary metabolism in PDK-knockout mice. We propose that this method will be useful in assessing metabolic disease states and developing therapies to improve PDH flux.

scholarly journals Investigation of the Hardening Reaction of Gelatin with 13C Labeled Formaldehyde by Solution and Solid State 13C NMR Spectroscopy

1991 ◽  
Vol 46 (3) ◽  
pp. 385-390 ◽  
Author(s):  
Klaus Albert ◽  
Ernst Bayer ◽  
Alfred Wörsching ◽  
Herbert Vögele
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
13C Nmr Spectroscopy ◽  
Drying Process ◽  
Primary Attack ◽  
Lysine Residues ◽  
Arginine Residues ◽  
C Nmr ◽  
Solid State 13C Nmr ◽  
Model Reactions

Model reactions of the hardening of gelatin with 13C labeled formaldehyde were monitored by 13C NMR spectroscopy in solution and in the solid state. In solution primary attack of formaldehyde first forms methylols of lysine residues and later of arginine residues, which react to a lysine-arginine crosslink. During the drying process of hardened gelatin, in addition to the lysine-arginine crosslink an arginine-arginine crosslink is formed. The rate of crosslink formation is strongly influenced by humidity.

Dimeric complexes of rare-earth substituted Keggin-type silicotungstates: syntheses, crystal structure and solid state properties

RSC Advances ◽  
2014 ◽  
Vol 4 (48) ◽  
pp. 25357-25364 ◽  
Author(s):  
Mukesh Kumar Saini ◽  
Rakesh Gupta ◽  
Swati Parbhakar ◽  
Anil Kumar Mishra ◽  
Rashi Mathur ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Analytical Techniques ◽  
Keggin Type ◽  
Dimeric Complexes ◽  
Complexes Of Rare Earth ◽  
C Nmr

A series of rare-earth substituted dimeric complexes of Keggin-type silicotungstates were synthesized and characterized using various analytical techniques like SCXD, photoluminescence, 1H and 13C NMR spectroscopy.

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