Molecular Complexes of Amino Acid (α-Alanine) and Their Manifestation in the Raman Spectra, Ab initio Calculations
Hakim Hushvaktov,
Abduvaxid Jumabaev,
Gulam Muradov,
Akhmad Absanov
Issue:
Volume 5, Issue 1, June 2021
Pages:
1-9
Received:
22 December 2020
Accepted:
4 January 2021
Published:
15 January 2021
DOI:
10.11648/j.ajqcms.20210501.11
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Abstract: The purpose of this work is to determine the role of hydrogen bonds in the crystallization of alanine, which includes carbooxyl COOH and amino NH2 groups, and the manifestation of these intermolecular interactions in the Raman spectra. FT-Raman spectra were analyzed and ab initio calculations by the RHF and B3LYP methods were performed in order to consider in more detail the possibility of the formation of aggregated intermolecular complexes in the crystalline state of α-alanine. The intra-molecular and inter-molecular interactions, the dynamics of molecular groups and structural changes of α-alanine have been studied by the method of Raman light scattering and ab initio calculations. Ab initio calculations have shown that the change in the Raman spectra is explained by the formation of several types of hydrogen bonds. These hydrogen bonds play a special role in the formation of the crystal structure of α-alanine. In Raman spectra, the presence of a hydrogen bond between molecules is manifested in the form of asymmetry and splitting of vibrational bands. An analysis of the Raman spectra of alanine with water shows that with an increase in the strength of the hydrogen bond leads to increase in the bond energy in the OH group. The hydrogen atom in the N-H group of the alanine molecule is actively involved in the formation of a hydrogen bond. It was shown by ab initio calculations that dimeric, trimeric and other chain molecular complexes exist in alanine. The complexes formed due to the hydrogen NH2 bond are weaker than those formed due to the OH bond. Upon the formation of a complex of alanine with water, the O-H vibration band shifts to the low-frequency side by 320 cm-1 and 415 cm-1, respectively. It was shown that an intramolecular hydrogen bond is formed between the NH and CO groups. It was found that in the Raman spectra of O-H and N-H, the alanine bands in the region of 2900-3050 cm-1 are complex and consist of several bands. The structure and connectivity of the bands is explained by the fact that the spectrum of the O-H bond consists of a symmetric valence band of vibrations and overtones of bending vibrations.
Abstract: The purpose of this work is to determine the role of hydrogen bonds in the crystallization of alanine, which includes carbooxyl COOH and amino NH2 groups, and the manifestation of these intermolecular interactions in the Raman spectra. FT-Raman spectra were analyzed and ab initio calculations by the RHF and B3LYP methods were performed in order to ...
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Influence of Unlike Proportions of Preliminary and Activated Sludge on Methane Generation During Anaerobic Co-digestion
Md. Nurul Islam Siddique,
Mohd Zamri Bin Ibrahim,
Mohd Mokhlesur Rahman
Issue:
Volume 5, Issue 1, June 2021
Pages:
10-15
Received:
20 April 2021
Accepted:
7 May 2021
Published:
27 May 2021
DOI:
10.11648/j.ajqcms.20210501.12
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Abstract: The aim of this study was to look into methane generation using different amounts of initial sludge (IS) and activated sludge (AS) for anaerobic transformation. To compare the best combination in analysis with a benchmark combination, C0, three experimental ratios (IS: AS) (v/v) were used: C1 (60: 40), C2 (80: 20), and C3 (100: 00). (40: 60). Anaerobic digestion was carried out at 37°C in mesophilic conditions with a 12 day HRT and a loading rate of 1.63 0.06 kg TVS/m3 day. In comparison to C0, biogas generation for ratios C1 and C2 increased from 25% to 38%. The maximum amount generated by combination C3, which was 52.44 percent more than that of C0, showed a clear improvement in specific methane generation. C1, which involves using less initial sludge and increasing activated sludge condensing, is the most realistic combination to use on a large scale. IS has a C/N proportion that is 2 times more than AS because of the higher organic compounds in IS. The obtained proportion of IS that ought to be added to AS to achieve the greatest methane production were 60 and 80% (combination C1 and C2), separately than the reference conditions, C0. Nevertheless, the influent ought to be deliberately arranged with a gradual increment to the ideal influent proportion to acclimatization of the microorganisms and avoid over-loading. 3.72 years are found to be the time needed to recover expenses.
Abstract: The aim of this study was to look into methane generation using different amounts of initial sludge (IS) and activated sludge (AS) for anaerobic transformation. To compare the best combination in analysis with a benchmark combination, C0, three experimental ratios (IS: AS) (v/v) were used: C1 (60: 40), C2 (80: 20), and C3 (100: 00). (40: 60). Anaer...
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