Molecular Structural Characterization Research Articles

Quantitative analysis of molecular structure characterization of different liptinite-rich coals using FTIR spectroscopy

As one of the important components in low-rank coals, liptinite plays an indispensable role in the formation and utilization of coal, thus, understanding the occurrence and structures of liptinite-rich coals provides a theoretical basis for the origin and clean utilization of coals. In this study, the occurrence of liptinite and the functional groups and molecular structure of different liptinite-rich coals were quantitatively characterized by using optical microscope and Fourier transform infrared spectroscopy (FTIR), respectively. The results showed that the sample JS-7 from Yunnan Province mainly enriched sporinite and bituminite, the sample JS-15 from Yunnan Province is rich in dispersed resin and the amber-rich coal from Liaoning Province mainly contains bulk resin. The FTIR results indicated that the amber-rich coal, the sample JS-7 and pure amber (Liaoning Province) consist mainly of trisubstituted benzene. The sample JS-7 has the highest content of trisubstituted benzene (63.4%) due to the high content of sporinite and bituminite. The sample JS-15 is mainly composed of tetrasubstituted and pentasubstituted benzene, which may be relevant to the cyclization of aliphatic chains and the decarboxylation reaction of benzene rings. The CC group has not been detected in the sample JS-7 and pure amber. The FTIR structural parameters indicate that the pure amber has the lowest maturity, the lowest degree of aromatization, but the highest hydrocarbon generation potential. The highest CH2/CH3 group value (14.69) and the lowest A factor value (0.36) of the sample JS-15 indicate a well-developed aliphatic chain structure and lowest hydrocarbon generation potential, respectively, which probably caused by the low content of CO group.

Fingerprint profiling for quality evaluation and the related biological activity analysis of polysaccharides from Liuweizhiji Gegen-Sangshen beverage.

Liuweizhiji Gegen-Sangshen beverage (LGS) is popular in China, which has been used for alleviating alcohol-mediated discomfort and preventing alcoholic liver disease (ALD). This beverage is consisted of six herbal components that are known as functional foods and fruits. LGS is rich in polysaccharides, however, the activity and quality evaluation of LGS-derived polysaccharides remain unexplored. The purpose of this study is thus to establish a comprehensive quality control methodology for the assessment of LGS polysaccharides (LGSP) and to further explore the anti-oxidant, anti-inflammatory as well as prebiotic effect of LGSP. LGSP was extracted, followed by analysis of molecular weight distribution, monosaccharide content and structural characterization via integrating the application of high-performance size exclusion chromatography (HPSEC), 1-phenyl-3-methyl-5-pyrazolone-HPLC (PMP-HPLC), fourier transform infrared spectroscopy (FT-IR) as well as nuclear magnetic resonance spectroscopy (NMR) techniques. The anti-oxidation activity of LGSP was determined by DPPH, ABTS, hydroxyl radical scavenging capacity and total antioxidant capacity. The anti-inflammation of LGSP were assessed on the RAW 264.7 cells. The effect of LGSP on growth of Lactobacillus, Bifidobacterium bifidum and Bifidobacterium adolescentis was evaluated. The results demonstrated that LGSP had two molecular weight distribution peaks, with the average molecular weights of (6.569 ± 0.12) × 104 Da and (4.641 ± 0.30) × 104 Da. LGSP was composed of 8 monosaccharides, with galacturonic acid, glucose rhamnose and galactose representing the highest molar ratios. Homogalacturonic acid (HG) type and rhamnosegalacturonic acid glycans I (RG-I) type and α-1,4-glucan were present in LGSP. LGSP concentration in LGS was 17.94 ± 0.28 mg/mL. Furthermore, fingerprint analysis combined with composition quantification of 10 batches of LGSP demonstrated that there was a high similarity among batches. Notably, LGSP exhibited anti-oxidant effect and inhibited expressions of pro-inflammatory factors (TNF-α and IL-6) in LPS-stimulated RAW 264.7 cells. In addition, LGSP remarkably promoted the proliferation of probiotics Lactobacillus, Bifidobacterium bifidum and Bifidobacterium adolescentis, showing good prebiotic activity. The results of present study would be of help to gain the understanding of structure-activity relationship of LGSP, provide a reference for quality evaluation of bioactive LGSP, and facilitate development of unique health and functional products in the future.

Molecular expression, purification and structural characterization of recombinant L-Glutaminase from Streptomyces roseolus

The present research reports the anti-cancer potential of recombinant L-Glutaminase from Streptomyces roseolus. L-Glutaminase gene was synthesized by codon-optimization, cloned and successfully expressed in E. coli BL21 (DE3). Affinity purified recombinant L-Glutaminase revealed a molecular mass of 32 kDa. Purified recombinant L-Glutaminase revealed stability at pH 7.0–8.0 with optimum activity at 70 °C further indicating its thermostable nature based on thermodynamic characterization. Recombinant L-Glutaminase exhibited profound stability in the presence of several biochemical parameters and demonstrated its metalloenzyme nature and was also found to be highly specific towards favorable substrate (l-Glutamine) based on kinetics. It demonstrated antioxidant property and pronounced cytotoxic effect against breast cancer (MCF-7 cell lines) in a dose dependent behavior with IC50 of 40.68 μg/mL. Matrix-assisted laser desorption ionization-time of flight-mass spectroscopy (MALDI-TOF-MS) analysis of desired mass peaks ascertained the recombinant L-Glutaminase identity. N-terminal amino acid sequence characterization through Edman degradation revealed highest resemblance for L-glutaminase within the Streptomyces sp. family. The purified protein was characterized structurally and functionally by employing spectroscopic methods like Raman, circular dichroism and nuclear magnetic resonance. The thermostability was assessed by thermogravimetric analysis. The outcomes of the study, suggests the promising application of recombinant L-Glutaminase as targeted therapeutic candidate for breast cancer.

3D molecular structural modeling and characterization of indium phosphide via irregularity topological indices

Indium phosphide (InP) is a binary semiconductor composed of indium and phosphorus. It has a zinc blende crystal structure, which is a type of cubic lattice structure. This lattice is composed of indium and phosphorus atoms arranged in a lattice of cube-shaped cells, with each cell containing four indium atoms and four phosphorus atoms. This lattice structure is the same for all materials with a zinc blende crystal structure and is the most common type of lattice structure in semiconductors. Indium phosphide (InP) has several chemical applications. It is commonly used as a dopant in the production of semiconductors, where it helps control the electrical properties of the material. InP is also utilized in the synthesis various indium-containing compounds, which can have applications in catalysts and chemical reactions. Additionally, InP nanoparticles have been investigated for their potential use in biomedical imaging and drug delivery systems. The topological characterization of 3D molecular structures can be performed via graph theory. In graph theory, the connections between atoms are represented as edges and the atoms themselves are represented as nodes. Furthermore, graph theory can be used to calculate the topological descriptors of the molecule such as the degree-based and reverse degree-based irregularity toplogical indices. These descriptors can be used to compare the topology of different molecules. This paper deals with the modeling and topological characterization of indium phosphide (InP)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$({\ ext{InP}})$$\\end{document} via degree-based and reverse irregularity indices. The 3D crystal structure of the InP is topologically modeled via partition of the edges, and derived closed form expressions for its irregularity indices. Our obtained results will be surely be helpful in investigating the QSPR/QSAR analysis as well as understanding the deep irregular behavior of the indium phosphide (InP)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$({\ ext{InP}})$$\\end{document}.

Molecular structure characterization of coal with different coalification degrees: a combined study from FT-IR, Raman, 13C NMR spectroscopy and modelling

While extensive research has been conducted on the evolution of coal's molecular structure during coalification, the heterogeneity and complexity of coal continue to impede the accurate and precise quantitative characterization of its structural evolution mechanism. In this study, the organic matter source, coal quality, carbon skeleton structure, and functional group occurrence of coal at different coalification stages have been determined using maceral identification, vitrinite reflectance, industrial quality, elemental analysis, and spectral analysis. Four molecular models have been created through computer-aided molecular design. The results indicate that the hydrogen atoms in the benzene ring structure reduce as coalification increases. The content of aliphatic compounds gradually decreases, while the length of aliphatic side chains first decreases (Ro,max<1.81%) and then increases (Ro,max>1.81%). Moreover, the chemical structure of coal tends to mature and stabilize, as the degree of coal crystallization increases, and the oxygen-containing groups gradually decrease. Therefore, aromatization increases with the condensation reaction dominating in the late stage of coalification. After intensive attempts to determine the chemical bond mode between aromatic carbon, aliphatic side chain, and oxygen functional group, the final molecular structure models are presented as C188H165O13N3 (F-1), C182H161O9N5 (J-1), C195H153O10N3 (T-1), and C193H129O7N3 (W-1). Furthermore, the mechanism of coalification is discussed based on the variation of the side chains and chemical bonds. According to the adsorption heat of functional groups, the methane adsorption capacity increases as the degree of coalification increases. The inflection point of methane adsorption capacity is at Ro,max>1.80%. This study provides a theoretical framework to understand the molecular structure evolution of coals at varying degrees of metamorphism. Additionally, it proposes a reliable method for characterizing coal molecular structures with high accuracy.

Atomic layer molecular beam epitaxy of kagome magnet RMn6Sn6 (R = Er, Tb) thin films

Kagome lattices have garnered substantial interest because their band structure consists of topological flat bands and Dirac cones. The RMn6Sn6 (R = rare earth) compounds are particularly interesting because of the existence of the large intrinsic anomalous Hall effect (AHE), which originates from the gapped Dirac cones near the Fermi level. This makes RMn6Sn6 an outstanding candidate for realizing the high-temperature quantum AHE. The growth of RMn6Sn6 thin films is beneficial for both fundamental research and potential applications. However, most of the studies on RMn6Sn6 have focused on bulk crystals, and the synthesis of RMn6Sn6 thin films has not been reported so far. Here, we report the atomic layer molecular beam epitaxy growth, structural and magnetic characterizations, and transport properties of ErMn6Sn6 and TbMn6Sn6 thin films. It is especially noteworthy that TbMn6Sn6 thin films have out-of-plane magnetic anisotropy, which is important for realizing the quantum AHE. Our work paves the avenue toward the control of the AHE using devices patterned from RMn6Sn6 thin films.

Molecular structure characterization of kerogen in contact metamorphic shales: Insights into the effect of graphitization on organic matter pores

Molecular structure characterization of kerogen in contact metamorphic shales: Insights into the effect of graphitization on organic matter pores

Lily Polysaccharide Nano‐Selenium Promotes A549 Cells Apoptosis through Cell Cycle Inhibition

AbstractThis study uses Lilium davidii var. unicolor (Lanzhou lily) polysaccharides extracted from bulbs to prepare nano‐selenium (nano‐Se) polysaccharide (LPS). Here, the study explores the molecular structure characterization, inhibition effects, and mechanisms of action of prepared LPS on A549 lung cancer cells. The LPS structure is characterized using Fourier‐transform infrared spectroscopy (FTIR), UV spectroscopy (UV–vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), X‐ray photoelectron spectroscopy (XPS), etc. Results show that selenized polysaccharides bonded through electrostatic adsorption, with an average LPS particle size of 243.75 nm and zeta potential of −38.3 mV, which can be stably preserved at 4 °C for more than 3 months. The in vitro antitumor activity experiment shows that the prepared LPS inhibited A549 cell proliferation while affecting cell migration. Cell cycle analysis shows that apoptosis is promoted by blocking the G1 phase, while during the late apoptosis stage cells accounted for 60%. RNA‐Seq data analysis shows that the main mechanisms of action on A549 cells are to inhibit DNA replication initiation genes, block the cell cycle, and regulate the expression of apoptosis‐related genes and proteins in promoting cell apoptosis.

Experimental and Simulation Studies of Imidazolium Chloride Ionic Liquids with Different Alkyl Chain Lengths for Viscosity Reductions in Heavy Crude Oil: The Effect on Asphaltene Dispersion.

Heavy crude oil poses challenges in terms of extraction and transportation due to its high viscosity. In the pursuit of effective methods to reduce viscosity in heavy crude oil, this study investigates the potential of imidazolium chloride ionic liquids with varying alkyl chain lengths as viscosity reducers. The experimental results demonstrate that the addition of 1-dodecyl-3-methylimidazole chloride ([C12-MIM]Cl) leads to a maximum viscosity reduction of 49.87%. Solubility parameters were calculated based on characterization of the average molecular structure of the asphaltenes. The viscosity reduction effect is enhanced when the solubility parameter of the ionic liquid closely matches that of the asphaltene. The initial asphaltene deposition point of heavy crude oil is increased from 63% to 68% with the addition of 150 mg/L [C12-MIM]Cl. Furthermore, the average particle size of asphaltene deposits decreases from 79.35 μm to 48.54 μm. The viscosity of heavy crude oil is influenced by the aggregation of asphaltenes. The ability of ionic liquids, especially those with longer alkyl chains, to disperse asphaltene molecules and reduce viscosity has been confirmed through molecular dynamics and quantum mechanical simulations.

Methods for molecular characterization of dissolved organic matter in the alpine water environment: an overview

The alpine area has become a sensitive indicator and amplifier of global climate change and human activities because of its unique geographical and climatic conditions. Being an essential part of biochemical cycling, dissolved organic matter (DOM) could effectively help understand the process, structure, and function of alpine aquatic ecosystems. Due to the low content and sampling difficulties, the analysis of DOM in alpine water demands high sensitivity with low sample volume, which has not been comprehensively reviewed. This review summarizes the DOM sampling, pretreatment, and analysis methods involving the characterization of concentration, spectroscopy, and molecular structure. Overall, conventional parameters are the basis of advanced characterization methods. Spectroscopic tests can reveal the optical properties of DOM in response to lights from ultraviolet to infrared wavelengths, to distinguish the chemical composition. Molecular structure characterizations can provide microscopic information such as functional groups, element ratios, and molecular weights. The combination of multiple methods can depict DOM composition from multiple perspectives. In sum, optimized sampling and pretreatment, high-sensitivity molecular characterization, and method integration are crucial for effectively analyzing DOM components in alpine waters. These perspectives help to standardize the DOM characterization process and to understand the correlation between DOM composition and its properties, as well as the migration and transformation of DOM.

Bioactive porphyrin magnesium (II) complex. Synthesis, molecular structure and spectroscopic characterization. Biological activity and molecular docking studies

We have synthesized and characterized porphyrin structures by UV–visible, IR and fluorescence spectroscopy studies and single crystal XRD analysis; H2(TPP) (I) (meso-tetraphenylporphyrin), [Mg(TPP)(DMF)] (II); (DMF: dimethylformamide) and [Mg(TPP)(H2O)]0.2(4-CNpy) (III); (4-CNpy: 4-Cyanopyridine). The crystal packing of the porphyrin structures is stabilized by intermolecular hydrogen bonds and by intermolecular CH⋯Cg π interactions where Cg is the centroid of the phenyl and pyrrole rings. UV–Vis spectroscopic data confirmed the creation of Mg-meso-porphyrin complexes by the red-shifted Soret bands for our derivatives compared to the free-base porphyrin. The optical gap energy values of (I), (II) and (III) are 1.92, 2.07 and 2.00 eV. Gram-positive and Gram-negative bacteria were tested against free porphyrin (I), metallated porphyrin (II) and complex (III). The results show that the magnesium porphyrin derivative is highly effective compared to H2TPP free-base porphyrins and metallated porphyrin [Mg(TPP)] and has higher inhibition character against the tested bacteria. The molecular docking of the complex (III), in the active sites of bacterial proteins was carried out to detect the degree of antibacterial activity of recognition.

Morphological, Molecular Structural and Physicochemical Characterization of Starch Granules Formed in Endosperm of Rice with Ectopic Overexpression of α-Amylase.

The objective of this study was to characterize the endosperm starch in rice that ectopically overexpressed the α-amylase. Transgenic rice plants, transformed with cauliflower mosaic virus 35S promoter driven AmyI-1 (35S::AmyI-1) and AmyII-4 (35S::AmyII-4), and 10 kDa prolamin promoter driven AmyI-1 (P10::AmyI-1), were cultivated under standard conditions (23 °C, 12 h in the dark/ 26 °C, 12 h in the light), and brown grains were subsequently harvested. Each grain displayed characteristic chalkiness, while electron microanalyzer (EPMA)-SEM images disclosed numerous small pits on the surface of the starch granules, attributable to α-amylase activity. Fluorescence labeling and capillary electrophoresis analysis of starch chain length distribution revealed no significant alterations in the starches of 35S::AmyI-1 and 35S::AmyII-4 transgenic rice compared to the wild-type. Conversely, the extremely short α-glucan chains (DP 2-8) exhibited a dramatic increase in the P10::AmyI-1 starch. Rapid visco-analyzer analysis also identified variations in the chain length distribution of P10::AmyI-1 starch, manifesting as changes in viscosity. Moreover, 1H-NMR analysis uncovered dynamic modifications in the molecular structure of starch in rice grain transformed with P10::AmyI-1, which was found to possess unprecedented structural characteristics.

Genome-Wide Computational Analysis of Dirrigent Proteins in Solanum Tuberosum

Dirrigent proteins are required for the synthesis of lignans, a distinct and widely distributed class of plant-derived secondary metabolites with promising pharmacologic characteristics and a potential role in plant defense. However, no detailed data on the Dirrigent family of Solanum tuberosum is known. Comparatively, 33 DIR sequences were explored in Solanum tuberosum in this research study. There are no introns in the majority of StDIR genes. A single Dirigent domain is found in all StDIR proteins. The abundance of amino acids, sequence similarity analysis, phylogenetic analysis, genomic location, gene structure, conserved domain analysis, evolutionary analysis, and gene promoter assessment are all studied. This study lays a foundation for potential plant genetic engineering and crop improvement research by providing an in-depth and thorough explanation of the detailed molecular mechanism and structural characterization of StDIR proteins in the genome of Solanum tuberosum. This work will provide useful data for enabling the proper selection of dirrigent proteins in higher plants and will support future studies on the DIR gene family.

Characterization of the starch molecular structure of wheat varying in the content of resistant starch

Resistant starch (RS) is the total amount of starch that is incompletely or not digested and absorbed in the small intestine. It plays a role similar to dietary fibre with beneficial effects for human health. In this study, the RS content of 129 wheat accessions was determined, and the relationship between the several starch physical properties and resistant starch content were analyzed. By comparing the total starch content, amylose starch content, starch chain length distribution, starch crystallization type, starch branching degree, and starch granule morphology between the high RS and low RS content wheat accessions, it was found that the amylose content and RS content were significantly positively correlated. However, in the range of chain length fb 3 (DP ≥ 37), there was a significant negative correlation between amylopectin content and RS content. The surface of starch granules became increasingly smooth as the content of RS increased.

Molecular Structure Characterization of Micro/Nanoplastics by 193 nm Ultraviolet Photodissociation Mass Spectrometry.

The degradation of macroplastics results in micro/nanoplastics (MNPs) in the natural environment, inducing high health risks worldwide. It remains challenging to characterize the accurate molecular structures of MNPs. Herein, we integrate 193 nm ultraviolet photodissociation (UVPD) with mass spectrometry to interrogate the molecular structures of poly(ethylene glycol) terephthalate and polyamide (PA) MNPs. The backbones of the MNP polymer can be efficiently dissociated by UVPD, producing rich types of fragment ions. Compared to high-energy collision dissociation (HCD), the structural informative fragment ions and corresponding sequence coverages obtained by UVPD were all improved 2.3 times on average, resulting in almost complete sequence coverage and precise structural interrogation of MNPs. We successfully determine the backbone connectivity differences of MNP analogues PA6, PA66, and PA610 by improving the average sequence coverage from 26.8% by HCD to 89.4% by UVPD. Our results highlight the potential of UVPD in characterizing and discriminating backbone connectivity and chain end structures of different types of MNPs.

Production of cellooligosaccharides from oil palm bunch in bio-based choline chloride deep eutectic solvents and MALDI-TOF MS analysis of COS mixture

Lignocellulosic biomass pretreatment and cellulose dissolution are principal challenges for its conversion to high-value chemicals, materials and fuels. This work focused on production of soluble cellooligosaccharides (COS) from palm bunch for future use as nutraceutical supplement to enhance human's immune and digestive systems. Deep eutectic solvents (DESs) have been found as eco-friendly, renewable and promising solvents selective for lignin and hemicellulose removal from biomass. Additionally, the investigation of most suitable DES for both cellulose dissolution and subsequently cleavage of cellulose to COS is crucial. In the study, palm empty fruit bunch (EFB) was pretreated in different DES for screening of most favorable cellulose inter- and intra-molecular structural dissolution in a combination with beta,1–4 glycosidic bond cleavage by elevated reaction temperature for COS production. ChCl/urea was found to be the most promising DES for dissolving 76.83% of EFB constituents. The highest COS production yield at 90.1%w/w based on treated EFB fraction (74.7% COS yield based on cellulose in native EFB) was achieved in ChCl/urea DES from cellulose fraction extracted from EFB at 240 °C for 20 min. The study additionally provided insightful characterization and elucidation of COS molecular structure using 2D-HSQC and MALDI-TOF/MS techniques. MALDI-TOF/MS was a promising and rapid technique for simultaneously qualitative and quantitative analysis of COS at different degrees of polymerization in COS product.

Raman spectroscopy and scanning electron microscopy application for physical characterization of horsehairs

Horsehairs present several common characteristics in their chemical composition and molecular structure. The present study aims to analyze the physical characteristics of horsehairs belonging to different breeds. Morphological analysis of the horsehair fibers was performed using Scanning Electron Microscopy (SEM) and molecular structural characterization using the Raman Spectroscopy (RS) technique. Horse hairs were collected from three different horse groups (group A: mixed-breed; group B: Italian saddle; group C: thoroughbred). Each group was constituted of five horses with a mean body weight of 475 ± 25 kg, aged between 12 and 15 years old. SEM images showed differences in the surface layer (cuticula) and diameter size of horsehairs referred to different breeds. The investigation conducted through RS showed differences in the S – O band, located at 1044 cm−1, where cysteic acid is one of the amino acid constituents of α-keratin; in CH2 bending mode and CH stretching, located at ~1450 cm-1 and ~2900 cm-1, respectively. These differences could be attributed to genetic predisposition or metabolism; they could represent the real differentiation among the breeds, detectable by using RS.

Synthesis, Characterization and in vitro Anticancer Activity of New Quinoline Analogues against Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) developed from mucosal lining of oral cavity is ranked as 6th most common cancer worldwide. Adverse effects of available anticancer agents intended present work to carry out the synthesis, characterization and evaluation of new quinoline analogues (NQA) against OSCC cell lines. In present study, substituted quinoline (1) was treated with ethyl chloroacetate to offer ester derivative (2), which on treatment with hydrazine hydrate yielded hydrazide derivative (3), which was cyclized into oxadiazole derivative (4) when cyclized with 4-methoxy benzoic acid. Characterization of molecular structures of synthesized NQAs was done based on the FTIR, 1H NMR, 13C NMR and mass spectrometric data. The characterized NQAs were investigated for their anticancer potential. The anticancer studies involved antiproliferation study (IC50 determination) against OSCC cell lines (CAL-27), followed by cell cycle analysis. The results of antiproliferation study of NQAs revealed that among all, NQA 3 exhibited lowest IC50 (3.26 μg/mL). Also, the results of cell cycle analysis of all NQA revealed that all NQAs caused cancer cells arrest in ‘S’ phase. The high anticancer activity of NQA 3 and ability of all the NQAs to cause CAL-27 cells arrest in ‘s’ phase supports their potential application in OSCC treatment. However, the synthesized NQAs must be additionally investigated for the in vivo and clinical studies.

Preparation and Molecular Structural Characterization of Fulvic Acid Extracted from Different Types of Peat.

Humic acid is a type of polymeric, organic weak acid mixture with a core aromatic structure and main-component oxygen-containing functional group. Fulvic acid is a type of humic substance that can be dissolved in acid, alkali, or water. This study discusses the influence of different peptides on the molecular structure of fulvic acid, which was extracted from herbaceous, woody, and mossy peats using alkaline dissolution and acid precipitation methods. Analyses using infrared, UV-Vis, 13C-NMR, and X-ray photoelectron spectroscopies, as well as X-ray diffraction (XRD), were conducted to compare the effects of different peat types on the content and molecular structure of fulvic acid. The woody peat fulvic acid content was the highest among all peat fulvic acids (0.38%). However, the yield of fulvic acid from herbaceous peat was the highest (2.53%). Herbaceous peat fulvic acid contains significant quantities of carbonyl, amino, methylene, carboxyl, and phenolic hydroxyl groups and ether bonds. Woody peat fulvic acid contains carbonyl and methoxy groups, benzenes, aromatic carbons, aromatic ethers, and phenols. The degree of aromatization of woody peat fulvic acid was the highest. Mossy peat fulvic acid contains high levels of hydroxy, methyl, methylene, and phenol groups and aromatic ethers. The structural differences in fulvic acids in the different types of peat were primarily manifested in the content of functional groups, with little influence from the types of functional groups. XRD analysis of the different peats revealed that their structures all comprised benzene rings. However, mossy peat contained more C=O and -COOH groups, whereas herbaceous peat contained more C-O groups.

Application of Organic Petrology and Raman Spectroscopy in Thermal Maturity Determination of the Karoo Basin (RSA) Shale Samples

An assessment performed using raman spectroscopy has found space in the black shales of the Cisuralian-age rocks of the Karoo Basin in South Africa, particularly those from the Guadalupian Ripon, Cisuralian Whitehill and Prince Albert Formations. It is used in conjunction with geochemical screening techniques such as organic petrology and programmed pyrolysis. In turn, the combination of these techniques is used for the assessment of the thermal maturity of the sedimentary organic matter from the perspective of hydrocarbon generation, retention, and expulsion. To provide further understanding of the black shales in the Cisuralian-age rocks of the Karoo Basin in South Africa, this study focuses on the characterization of samples from the KWV−01 borehole drilled in the southeastern Karoo Basin. In addition, the USA Devonian/Carboniferous Berea Sandstone project samples were included for comparison, and were used as a quality assurance measure. Organic petrology was utilized to assess the organic quality and thermal maturity of the black shales. The results obtained showed that the Karoo Basin shales are overmature, containing an abundance of solid bitumen, and this often characterizes a shale reservoir with moveable hydrocarbons (shale gas). The programmed pyrolysis analysis conducted on the black shales of the Karoo Basin yielded artifact results, as they were determined from a very low and poorly defined S2 peak. This indicated the shales to be overmature and categorized them to be of poor hydrocarbon generation potential. Raman spectroscopy was used to gain insights about the molecular structure of the black shales and to assess if this technique could be used as a complimentary tool to determine the thermal maturity of the shale samples. Raman parameters such as G–D1 Band separation, G and D1 band full width at half maximum (Gfwhm and D1fwhm) and G band position were successfully correlated with vitrinite reflectance (RoV), demonstrating a good potential for Raman spectroscopy to predict the thermal maturity of the shales. Overall, the study provides valuable information and knowledge concerning black shale sample characterization (particularly the thermal maturity and molecular structural characterization) in the Karoo Basin, South Africa.