The medium-term effect of natural compost on the spectroscopic properties of humic acids of Czech soils

2018 ◽  
Vol 156 (7) ◽  
pp. 877-887 ◽  
Author(s):  
V. Enev ◽  
L. Doskočil ◽  
L. Kubíková ◽  
M. Klučáková

AbstractIn the current work, humic acids (HAs) isolated from natural compost and unamended and amended soils in a medium-time field experiment were characterized to evaluate the effects of the amendment at rates of 124, 239 and 478 t/ha on their chemical, compositional and structural features. The impact of the application of compost on their properties was observed over 3 years. Humic acids were characterized using spectral methods and elemental analysis. Humic acid isolated from compost was predominantly aliphatic, with a larger content of nitrogen and low degree of aromaticity and humification. The typical maximum (280/345 nm) of HA obtained from compost lies within the T (tryptophan-like) region, which can be ascribed to proteinaceous organic materials. On the other hand, the HAs obtained from amended soil were mainly aromatic in character, with a larger distribution of oxygen-containing functional groups, molecular weight and greater aromaticity. Fluorophores of HAs obtained from amended soil lie within the C (humic-like) region with typical maxima centred in the range 430–450/500–540 nm, occurring usually in HAs isolated from soil, peat and lignite. According to ultra-violet/visible and Fourier-transform infrared (FTIR) spectroscopy, the larger oxygen contents of these HAs are associated with the substitution of aromatic rings by oxygen-containing functional groups such as carboxylic, hydroxyls and ethers. On the basis of FTIR spectra, it was shown that HAs obtained from amended soil 2 and 3 years after compost application were enriched by peptid, aromatic and polysaccharide compounds absorbing at 1540, 1515 and 1040/cm, respectively.

2019 ◽  
Vol 16 (11) ◽  
pp. 4601-4604
Author(s):  
M. Osnitsky Evgeny ◽  
A. Gurova Olga ◽  
V. Boroduy Davyd ◽  
V. Litvinenko Natalia ◽  
V. Grekhova Iraida

This article describes qualitative and quantitative characteristics of chemical elements and acidbase functional groups of humic acids (HA) in five lakes of the left bank of the Ob of Khanty-Mansi Autonomous Okrug-Yugra. The data on their elemental composition (CNHO), atomic ratios (H/C, O/C) carboxyl (COOH) and phenolic (OH) functional groups have been presented. The relationship between the elemental and functional composition of HA has been traced. It is found that with increasing hydrogen content, the percentage of carboxyl groups in the macromolecule of HA increases, the proportion of aromatic moieties reduces, and with increasing oxygen content the number of phenolic hydroxyls increases. According to the chart of atomic ratios describing the content of aromatic and aliphatic parts, HA are placed in the sequence, characterizing the maximum proportion of aromatic structures. Clearly there is a group of HA of lake Shchuchye sapropel, which is characterized by a maximum degree of aromaticity, followed by in decreasing order according to the contents of the Carom humic acids of sapropels of lakes Srednesatyginskiy Tuman, Nyartur, Medvezhye and Satyginskiy Tuman. The highest content of the Carom is typical for the more formed, “mature” HA.


2015 ◽  
Vol 1085 ◽  
pp. 3-6 ◽  
Author(s):  
Malika P. Mirzobekzoda ◽  
Elizaveta V. Maltseva ◽  
Natalya S. Shekhovtsova

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.


2020 ◽  
Vol 22 (1) ◽  
pp. 155
Author(s):  
Mikhail V. Diachkov ◽  
Karoll Ferrer ◽  
Jana Oklestkova ◽  
Lucie Rarova ◽  
Vaclav Bazgier ◽  
...  

Brassinosteroids are a class of plant hormones that regulate a broad range of physiological processes such as plant growth, development and immunity, including the suppression of biotic and abiotic stresses. In this paper, we report the synthesis of new brassinosteroid analogues with a nitrogen-containing side chain and their biological activity on Arabidopis thaliana. Based on molecular docking experiments, two groups of brassinosteroid analogues were prepared with short and long side chains in order to study the impact of side chain length on plants. The derivatives with a short side chain were prepared with amide, amine and ammonium functional groups. The derivatives with a long side chain were synthesized using amide and ammonium functional groups. A total of 25 new brassinosteroid analogues were prepared. All 25 compounds were tested in an Arabidopsis root sensitivity bioassay and cytotoxicity screening. The synthesized substances showed no significant inhibitory activity compared to natural 24-epibrassinolide. In contrast, in low concentration, several compounds (8a, 8b, 8e, 16e, 22a and 22e) showed interesting growth-promoting activity. The cytotoxicity assay showed no toxicity of the prepared compounds on cancer and normal cell lines.


Biochar ◽  
2021 ◽  
Author(s):  
Ngitheni Winnie-Kate Nyoka ◽  
Ozekeke Ogbeide ◽  
Patricks Voua Otomo

AbstractTerrestrial and aquatic ecosystems are increasingly threatened by pesticide pollution resulting from extensive use of pesticides, and due to the lack of regulatory measures in the developing world, there is a need for affordable means to lessen environmental effects. This study aimed to investigate the impact of biochar amendment on the toxicity of imidacloprid to life-cycle parameters and biomarker responses of the earthworm Eisenia fetida. E. fetida was exposed to 10% biochar-amended and non-amended OECD artificial soils spiked with 0, 0.75, 1.5, 2.25 and 3 mg imidacloprid/kg for 28 days. An LC50 of 2.7 mg/kg was only computed in the non-amended soil but not in the biochar-amended soil due to insignificant mortality. The EC50 calculated in the non-amended soil (0.92 mg/kg) for reproduction (fertility) was lower than the one computed in the biochar amended (0.98 mg/kg), indicating a decrease in toxicity in the biochar-amended substrate. Significant weight loss was observed at the two highest imidacloprid treatments in the non-amended soil and only at the highest treatment in the biochar-amended substrate, further highlighting the beneficial effects of biochar. Catalase activity decreased significantly at the two highest concentrations of non-amended soil. Yet, in the amended soil, the activity remained high, especially in the highest concentration, where it was significantly higher than the controls. This indicated more severe oxidative stress in the absence of biochar. In all non-amended treatments, there was a significant acetylcholinesterase inhibition, while lower inhibition percentages were observed in the biochar-amended soil. In most endpoints, the addition of biochar alleviated the toxic effects of imidacloprid, which shows that biochar has the potential to be useful in soil remediation. However, there is still a need for field studies to identify the most effective application rate of biochar for land application.


Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1486
Author(s):  
Eugene B. Caldona ◽  
Ernesto I. Borrego ◽  
Ketki E. Shelar ◽  
Karl M. Mukeba ◽  
Dennis W. Smith

Many desirable characteristics of polymers arise from the method of polymerization and structural features of their repeat units, which typically are responsible for the polymer’s performance at the cost of processability. While linear alternatives are popular, polymers composed of cyclic repeat units across their backbones have generally been shown to exhibit higher optical transparency, lower water absorption, and higher glass transition temperatures. These specifically include polymers built with either substituted alicyclic structures or aromatic rings, or both. In this review article, we highlight two useful ring-forming polymer groups, perfluorocyclobutyl (PFCB) aryl ether polymers and ortho-diynylarene- (ODA) based thermosets, both demonstrating outstanding thermal stability, chemical resistance, mechanical integrity, and improved processability. Different synthetic routes (with emphasis on ring-forming polymerization) and properties for these polymers are discussed, followed by their relevant applications in a wide range of aspects.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Amandine Leroy ◽  
Xavier Falourd ◽  
Loïc Foucat ◽  
Valérie Méchin ◽  
Fabienne Guillon ◽  
...  

Abstract Background Biomass recalcitrance is governed by various molecular and structural factors but the interplay between these multiscale factors remains unclear. In this study, hot water pretreatment (HWP) was applied to maize stem internodes to highlight the impact of the ultrastructure of the polymers and their interactions on the accessibility and recalcitrance of the lignocellulosic biomass. The impact of HWP was analysed at different scales, from the polymer ultrastructure or water mobility to the cell wall organisation by combining complementary compositional, spectral and NMR analyses. Results HWP increased the kinetics and yield of saccharification. Chemical characterisation showed that HWP altered cell wall composition with a loss of hemicelluloses (up to 45% in the 40-min HWP) and of ferulic acid cross-linking associated with lignin enrichment. The lignin structure was also altered (up to 35% reduction in β–O–4 bonds), associated with slight depolymerisation/repolymerisation depending on the length of treatment. The increase in $${T}_{1\rho }^{H}$$ T 1 ρ H , $${T}_{HH}$$ T HH and specific surface area (SSA) showed that the cellulose environment was looser after pretreatment. These changes were linked to the increased accessibility of more constrained water to the cellulose in the 5–15 nm pore size range. Conclusion The loss of hemicelluloses and changes in polymer structural features caused by HWP led to reorganisation of the lignocellulose matrix. These modifications increased the SSA and redistributed the water thereby increasing the accessibility of cellulases and enhancing hydrolysis. Interestingly, lignin content did not have a negative impact on enzymatic hydrolysis but a higher lignin condensed state appeared to promote saccharification. The environment and organisation of lignin is thus more important than its concentration in explaining cellulose accessibility. Elucidating the interactions between polymers is the key to understanding LB recalcitrance and to identifying the best severity conditions to optimise HWP in sustainable biorefineries.


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 962
Author(s):  
Andrzej Marczuk ◽  
Vasily Sysuev ◽  
Alexey Aleshkin ◽  
Petr Savinykh ◽  
Nikolay Turubanov ◽  
...  

Mixing is one of the most commonly used processes in food, animal feed, chemical, cosmetic, etc., industries. It is supposed to provide high-quality homogenous, nutritious mixtures. To provide appropriate mixing of materials while maintaining the process high efficiency and low energy consumption it is crucial to explore and describe the material flow caused by the movement of mixing elements and the contact between particles. The process of mixing is also affected by structural features of the machine components and the mixing chamber, speed of mixing, and properties of the mixed materials, such as the size of particles, moisture, friction coefficients. Thus, modeling of the phenomena that accompany the process of mixing using the above-listed parameters is indispensable for appropriate implementation of the process. The paper provides theoretical power calculations that take into account the material speed change, the impact of the material friction coefficient on the screw steel surface and the impact of the friction coefficient on the material, taking into account the loading height of the mixing chamber and the chamber loading value. Dependencies between the mixer power and the product degree of fineness, rotational speed of screw friction coefficients, the number of windings per length unit, and width of the screw tape have been presented on the basis of a developed model. It has been found that power increases along with an increase in the value of these parameters. Verification of the theoretical model indicated consistence of the predicted power demand with the power demand determined in tests performed on a real object for values of the assumed, effective loading, which was 65–75%.


2017 ◽  
Vol 70 (11) ◽  
pp. 1227 ◽  
Author(s):  
Carol Hua ◽  
Stone Woo ◽  
Aditya Rawal ◽  
Floriana Tuna ◽  
James M. Hook ◽  
...  

A series of electroactive triarylamine porous organic polymers (POPs) with furan, thiophene, and selenophene (POP-O, POP-S, and POP-Se) linkers have been synthesised and their electronic and spectroscopic properties investigated as a function of redox state. Solid state NMR provided insight into the structural features of the POPs, while in situ solid state Vis-NIR and electron paramagnetic resonance spectroelectrochemistry showed that the distinct redox states in POP-S could be reversibly accessed. The development of redox-active porous organic polymers with heterocyclic linkers affords their potential application as stimuli responsive materials in gas storage, catalysis, and as electrochromic materials.


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