scholarly journals A comparative study on the structural features of humic acids extracted from lignites using comprehensive spectral analyses

RSC Advances ◽  
2020 ◽  
Vol 10 (37) ◽  
pp. 22002-22009 ◽  
Author(s):  
Yuanqin Zhang ◽  
Yanhong Li ◽  
Liping Chang ◽  
Changyu Zi ◽  
Guangbing Liang ◽  
...  
Keyword(s):  
Comparative Study ◽  
Humic Acids ◽  
Structural Features ◽  
Spectral Analyses ◽  
C Nmr

The structural features of humic acids extracted from Zhaotong and Mile lignites were analyzed using comprehensive spectral analyses including UV-vis, FTIR, CP/MAS 13C NMR, XRD and XPS.

THE EXTRACTION OF ORGANIC MATTER FROM SELECTED SOILS AND PARTICLE SIZE FRACTIONS WITH 0.5 M NaOH AND 0.1 M Na4P2O7 SOLUTIONS

1989 ◽  
Vol 69 (2) ◽  
pp. 253-262 ◽  
Author(s):  
M. SCHNITZER ◽  
P. SCHUPPLI
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acids ◽  
Nmr Spectra ◽  
Attractive Alternative ◽  
Particle Size Fractions ◽  
Molecular Weights ◽  
Naoh Solution ◽  
C Nmr ◽  
Medium Silt

Organic matter (OM) in the Bainsville and Melfort soils, and in coarse clay and medium silt fractions separated from these soils, was extracted under N2 with 0.5 M NaOH and unadjusted 0.1 M Na4P2O7 solutions. pH ranges of the soils and fractions in contact for 24 h with 0.5 M NaOH and 0.1 M Na4P2O7 solutions extended from 12.2 to 12.6 and 9.0 to 9.4, respectively. Slightly greater proportions of the soil-carbon were extracted by 0.5 M NaOH than by 0.1 M Na4P2O7 solution. The differences, however, did not appear to be significant and may vary from soil to soil. The efficiency of extraction and the characteristics of the extracted materials were assessed on humic acids (HAs), which were isolated from the extracts. From the Bainsville soil and fractions, 0.1 M Na4P2O7 solution extracted more high-molecular weight and more deeply colored HAs than did 0.5 M NaOH solution. But HAs extracted from the Melfort soil and fractions had similar molecular weights and colours. 13C NMR spectra showed that HAs extracted by 0.1 M Na4P2O7 solution tended to be more aromatic than HAs extracted by 0.5 M NaOH solution. Well defined solid-state 13C NMR spectra of HAs, containing up to 69.0% ash, could be recorded. Unadjusted 0.1 M Na4P2O7 solution under N2 was found to be an attractive alternative to 0.5 M NaOH solution as an extractant for soil OM. Key words: Humic acids, E4:E6 ratios, IR spectra, 13C NMR spectra, aromaticity

Polysaccharides from the roots ofAlthaea officinalis L.: Structural features of D-glucans

1984 ◽  
Vol 49 (11) ◽  
pp. 2674-2679 ◽  
Author(s):  
Peter Capek ◽  
Rudolf Toman ◽  
Jozef Rosík ◽  
Alžbeta Kardošová ◽  
František Janeček
Keyword(s):  
Medicinal Plant ◽  
Structural Features ◽  
Gel Chromatography ◽  
Linear Character ◽  
Molecular Weights ◽  
Glycosidic Bonds ◽  
Althaea Officinalis ◽  
C Nmr

From the roots of the medicinal plant Althaea officinalis L., three D-glucans were isolated by gel chromatography which differed in molecular weights. The results of methylation analyses and 13C NMR measurements indicated predominantly linear character of the polysaccharide chains composed of α-D-glucopyranose units linked by 1 → 6 glycosidic bonds almost exclusively. The polymers had essentially the same structural features as D-glucan isolated from the leaves of this plant.

Alkinol- und Alkindiol-substituierte Titanocen-Komplexe; Synthese, Reaktionsverhalten und Strukturmerkmale / Alkyne-ol and Alkyne-diol Substituted Titanocene Complexes; Synthesis, Reaction Behaviour and Structural Features

1995 ◽  
Vol 50 (6) ◽  
pp. 923-930 ◽  
Author(s):  
Heinrich Lang ◽  
Katrin Köhler ◽  
Mathias Herres ◽  
Christiane Emmerich
Keyword(s):  
Spectroscopic Data ◽  
Structural Features ◽  
Synthesis Reaction ◽  
Addition Compound ◽  
X Ray ◽  
C Nmr

The reaction of (η5-C5H4SiMe3)2TiCl2 (1) with HO(CH2)nC ≡ CR (2a: n = 1, R = H; 2b: n = 1, R = CH3; 2c: n = 1, R = CH2OH ; 3: n = 2, R = H; 4: n = 4, R = H) affords in toluene at 25 °C in the presence of NEt3 the monoalkyne-ol substituted titanocenes (η5-C5H4SiMe3)2Ti(Cl)[O(CH2)nC ≡ CR] (5a: n = 1. R = H; 5b: n = 1, R = CH3; 5c: n = 1, R = C H2OH; 6: n = 2, R = H; 7: n = 4. R = H ). Compound 5c reacts with one equivalent of 1 in the presence of NEt3 to yield (η5-C5H4SiMe3)2(Cl)Ti-OCH2C ≡ CCH2O -Ti(Cl)(η5-C5H4SiMe3)2 (8). In addition, compound 8 can be synthesized directly by treatment of (η5- C5H4SiMe3)2TiCl2 (1) with 0.5 equivalents of HOCH9C≡CCH2OH (2c) in the presence of NEt3. The reaction of (η5-C5H4SiMe3)2Ti(Cl)(OCH2C ≡ CCH3) (5b) with Co2(CO)8 (9) yields (η5-C5H4SiMe3)2Ti(Cl)[(η2-OCH2C ≡ CCH3)Co2(CO)6] (10). Treatment of 5b or 10 with HCl(aq) (11) leads to the formation of (η5-C5H4SiMe3)2TiCl2 (1) and HOCH2C ≡ CCH3 (2b) (reaction of 5b with 11) or (η5-C5H4SiMe3)2TiCl2 (1) and [(η2-HOCH2C ≡ CCH3)Co2(CO)6] (12) (reaction of 10 with 11). All compounds have been characterized by analytical and spectroscopic data (IR , 1H, 13C NMR, MS) and (η5-C5H4SiMe3)2Ti(Cl)(OCH2C ≡ CCH3) (5b) by X -ray analysis.

Comparative study of dG affinity vs. DNA methylation modulating properties of side chain derivatives of procainamide: insight into its DNA hypomethylating effect

RSC Advances ◽  
2016 ◽  
Vol 6 (7) ◽  
pp. 5350-5358 ◽  
Author(s):  
R. L. Gawade ◽  
D. K. Chakravarty ◽  
J. Debgupta ◽  
E. Sangtani ◽  
S. Narwade ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Comparative Study ◽  
Structural Features ◽  
Side Chain ◽  
Side Chains ◽  
Hypomethylating Agents ◽  
Derivatives Of ◽  
Insight Into

Structural features of side-chains govern the association of procainamide and its derivatives with dG base of CpG rich DNA, which may differentially hinder the activity of DNMT-1, thereby they act as DNA hypomethylating agents.

Effects of compost-derived humic acids on vegetable biomass production and microbial growth within a plant (Cichorium intybus)-soil system: a comparative study

1996 ◽  
Vol 58 (2-3) ◽  
pp. 133-144 ◽  
Author(s):  
Manuela M. Valdrighi ◽  
Antonio Pera ◽  
Monica Agnolucci ◽  
Stefania Frassinetti ◽  
Deborah Lunardi ◽  
...  
Keyword(s):  
Comparative Study ◽  
Biomass Production ◽  
Humic Acids ◽  
Microbial Growth ◽  
Cichorium Intybus ◽  
Soil System ◽  
System A

scholarly journals A comparative study of the kinetics and stereochemistry of the serine hydroxymethyltransferase- and tryptophan synthase-catalysed exchange of the pro-2R and pro-2S protons of glycine

1991 ◽  
Vol 274 (3) ◽  
pp. 807-812 ◽  
Author(s):  
J P G Malthouse ◽  
J J Milne ◽  
L S Gariani
Keyword(s):  
Comparative Study ◽  
Exchange Rates ◽  
Exchange Process ◽  
Structural Features ◽  
Serine Hydroxymethyltransferase ◽  
Tryptophan Synthase ◽  
Order Of Magnitude ◽  
Step Mechanism

The stereospecificity of the serine hydroxymethyltransferase (EC 2.1.2.1)- and tryptophan synthase (EC 4.2.1.20)- catalysed exchange of the pro-2R and pro-2S alpha-protons of glycine was investigated by using 13C n.m.r. The exchange process is described in terms of a minimal four-step mechanism, and a method for analysing the exchange process by complete progress curves is presented. It is shown that serine hydroxymethyltransferase does not have absolute stereospecificity for the pro-2S-proton of glycine, but it catalyses the exchange of this proton 7400 times faster than the pro-2R proton of glycine. Tryptophan synthase is shown preferentially to catalyse the exchange of the pro-2R proton of glycine at a rate 380 times faster than the pro-2S proton of glycine. The exchange rates for the rapidly exchanged alpha-protons of glycine are similar for both enzymes. However, the exchange rates of the slowly exchanged alpha-protons differ by an order of magnitude. The structural features that may be responsible for the differences in the stereospecificity of the two enzymes are discussed.

Aspects of structural features in lignite and lignite humic acids

2006 ◽  
Vol 87 (9) ◽  
pp. 829-839 ◽  
Author(s):  
J. Peuravuori ◽  
P. Žbánková ◽  
K. Pihlaja
Keyword(s):  
Humic Acids ◽  
Structural Features ◽  
Lignite Humic Acids

Analysis of Structural Features of Humic Acids Fractions after Mechanochemical Modification

2015 ◽  
Vol 1085 ◽  
pp. 3-6 ◽  
Author(s):  
Malika P. Mirzobekzoda ◽  
Elizaveta V. Maltseva ◽  
Natalya S. Shekhovtsova
Keyword(s):  
Chemical Composition ◽  
Ir Spectroscopy ◽  
Humic Acids ◽  
Fulvic Acids ◽  
Structural Features ◽  
Acid Base ◽  
Structural Composition ◽  
Mechanochemical Modification ◽  
The Impact ◽  
First Time

Humic substances are the major components of soil, peat and brown coal. They can be fractionating into fulvic acids (FA), brown humic acids (BHA) and gray humic acids (GHA). In this work we investigated the influence of mechanochemical modifications on structural composition of HAs main fractions using the methods of IR and 1H MRS spectroscopy. The IR spectroscopy results has shown that HA has different chemical composition in comparison with GHA and BHA. Potentiometric titration showed that mechanoactivation (MA) with thiourea increases the amount of oxygen-containing groups up to 2.5. For the first time we studied the impact of modifying agent of thiourea on the structural composition and acid-base properties of HAs major fractions - GHA and BHA during the mechanoactivation process.

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