Enrichment Method Research Articles

Optimizing environmental enrichment for Sprague Dawley rats: Exemplary insights into the liver proteome.

Considering the expected increase in the elderly population and the growing emphasis on aging-related biomedical research, the demand for aged laboratory animals has surged, challenging established husbandry practices. Our objective was to establish a cost-effective method for environmental enrichment, utilizing the liver as a representative organ to assess potential metabolic changes in response to differing enrichment levels. We conducted a six-month study involving 24 male Sprague Dawley rats, randomly assigned to four environmental enrichment groups. Two groups were housed in standard cages, while the others were placed in modified rabbit cages. Half of the groups received weekly playtime in an activity focused rat housing unit. We evaluated hormone levels, playtime behavior, and subjective handling experience. Additionally, liver tissue proteomic analysis was performed. Initial corticosterone levels and those after 3 and 6 months showed no significant differences. Yet, testosterone levels were lower in the control group by the end of the study (p = 0.007). We observed 1871 distinct proteins in liver tissue, with 77% being common across groups. In gene ontology analysis, no specific pathways were overexpressed. In semiquantitative analysis, we observed differences in proteins associated in lipid metabolism such as Apolipoprotein A-I and Acyl-CoA 6-desaturase, which were lower in the control group (p = 0.024 and p = 0.009). Rats in the intervention groups with weekly playtime displayed the least amount of reported distress during inspection or upon room entry and were less prone to accepting treats. Removing animals from their enclosure was most effortless for those in the large cage group. Over time, there was a decrease in conflicts among rats that interacted only twice weekly during playpen time. In summary, refining husbandry practices for aging rats is both simple and budget-friendly, with no apparent adverse effects on stress levels, animal development, or relevant metabolic changes in the liver.

Automated Immunoprecipitation Workflow for Comprehensive Acetylome Analysis.

Immunoprecipitation is one of the most effective methods for enrichment of lysine-acetylated peptides for comprehensive acetylome analysis using mass spectrometry. Manual acetyl peptide enrichment method using non-conjugated antibodies and agarose beads has been developed and applied in various studies. However, it is time-consuming and can introduce contaminants and variability that leads to potential sample loss and decreased sensitivity and robustness of the analysis. Here we describe a fast, automated enrichment protocol that enables reproducible and comprehensive acetylome analysis using a magnetic bead-based immunoprecipitation reagent.

Proposal of an innovative MCDA evaluation methodology: knowledge discovery through rank reversal, standard deviation, and relationship with stock return

Financial performance analysis is of vital importance those involved in a business (e.g., shareholders, creditors, partners, and company managers). An accurate and appropriate performance measurement is critical for decision-makers to achieve efficient results. Integrated performance measurement, by its nature, consists of multiple criteria with different levels of importance. Multiple Criteria Decision Analysis (MCDA) methods have become increasingly popular for solving complex problems, especially over the last two decades. There are different evaluation methodologies in the literature for selecting the most appropriate one among over 200 MCDA methods. This study comprehensively analyzed 41 companies traded on the Borsa Istanbul Corporate Governance Index for 10 quarters using SWARA, CRITIC, and SD integrated with eight different MCDA method algorithms to determine the position of Turkey's most transparent companies in terms of financial performance. In this study, we propose "stock returns" as a benchmark in comparing and evaluating MCDA methods. Moreover, we calculate the "rank reversal performance of MCDA methods". Finally, we performed a "standard deviation" analysis to identify the objective and characteristic trends for each method. Interestingly, all these innovative comparison procedures suggest that PROMETHEE II (preference ranking organization method for enrichment of evaluations II) and FUCA (Faire Un Choix Adéquat) are the most suitable MCDA methods. In other words, these methods produce a higher correlation with share price; they have fewer rank reversal problems, the distribution of scores they produce is wider, and the amount of information is higher. Thus, it can be said that these advantages make them preferable. The results show that this innovative methodological procedure based on 'knowledge discovery' is verifiable, robust and efficient when choosing the MCDA method.

Speech enhancement augmentation for robust speech recognition in noisy environments

Abstract. The use of augmentations as a data enrichment method has become an important element in improving the performance of speech recognition systems. To work effectively in noisy conditions, augmentation is usually used to simulate the presence of background noise. However, the quality of speech recognition on samples pre-processed by noise reduction models does not increase. This paper proposes a new approach to speech data augmentation when training ASR systems, intended for their joint use with models for speech enhancement. It was based on the creation of several additional data samples containing speech samples processed by the enhancement model. The proposed approach was tested on the E-Branchformer neural network model using data from the Librispeech set. The quality of speech samples was assessed using the DNSMOS metric. By means of a 100-hour sample of clean speech samples it was shown that the proposed augmentation allows for an improvement in the WER metric of more than 4% in absolute value compared to the generally accepted approach based on adding noisy speech samples. Experiments on 960-hour data demonstrated the robustness of this approach as the training set size increased.

Tractable Data Enriched Distributionally Robust Chance-Constrained Conservation Voltage Reduction

This paper proposes a tractable distributionally robust chance-constrained conservation voltage reduction (DRCC-CVR) method with enriched data-based ambiguity set in unbalanced three-phase distribution systems. The increasing penetration of distributed renewable generation not only brings clean power but also challenges the voltage regulation and energy-saving performance of CVR by introducing high uncertainties to distribution systems. In most cases, the conventional robust optimization methods for CVR only provide conservative solutions. To better consider the impacts of load and PV generation uncertainties on CVR implementation in distribution systems and provide less conservative solutions, this paper develops a data-based DRCC-CVR model with tractable reformulation and data enrichment method. Even though the uncertainties of load and photovoltaic (PV) can be captured by data, the availability of smart meters (SMs) and micro-phasor measurement units (PMUs) is restricted by cost budget. The limited data access may hinder the performance of the proposed DRCC-CVR. Thus, we further present a data enrichment method to statistically recover the high-resolution load and PV generation data from low-resolution data with Gaussian Process Regression (GPR) and Markov Chain (MC) models, which can be used to construct a data-based moment ambiguity set of uncertainty distributions for the proposed DRCC-CVR. Finally, the nonlinear power flow and voltage dependant load models and DRCC with moment-based ambiguity set are reformulated to be computationally tractable and tested on a real distribution feeder in Midwest U. S. to validate the effectiveness and robustness of the proposed method.

Chemical reagents for the enrichment of modified peptides in MS-based identification.

Chemical reagents with special groups as enrichable handles have empowered the ability to label and enrich modified peptides. Here is an overview of different chemical reagents with affinity tags to isolate labeled peptides and the latest developments of enrichment strategies. Biotin is the most used affinity tag due to its high interaction with avidin. To decrease the unfavorable influence of biotin for its poor efficiency in ionization and fragmentation in downstream MS analysis, cleavable moieties were installed between the reactive groups and biotin to release labeled peptides from the biotin. To minimize the steric hindrance of biotin, a two-step method was developed, for which alkyne- or azide-tagged linkers were firstly used to label peptides and then biotin was installed through click chemistry. Recently, new linkers using a small phosphonic acid as the affinity tag for IMAC or TiO2 enrichment have been developed and successfully used to isolate chemically labeled peptides in XL-MS. A stable P-C instead of P-O bond was introduced to linkers to differentiate labeled and endogenous phosphopeptides. Furthermore, a membrane-permeable phosphonate-containing reagent was reported, which facilitated the study of living systems. Taking a cue from classic chemical reactions, stable metal-complex intermediates, including cobalt and palladium complexes, have been developed as peptide purification systems. Advanced enrichment strategies have also been proposed, such as the two-stage IMAC enrichment method and biotin-based two-step reaction strategy, allowing the reduction of unwanted peptides and improvements for the analysis of specific labeled peptides. Finally, future trends in the area are briefly discussed.

Temporal and spatial distribution and genesis of primary indium deposits around the world

Because rare dispersed elements including indium play an increasingly extensive and indispensable role in the field of modern high technology, the exploration, development and research of its resources are in full swing. The abundance of indium in the earth's crust is extremely low, and its original independent deposits have not been found so far. Indium is mainly parasitic in bulk non-ferrous metal deposits in the form of associated by-products. Because of its origin, the genetic types of indium deposits are as diverse as those non-ferrous metal deposits it parasitizes. The distribution of indium in geological time and earth space is uneven. The formation of indium ore deposit is closely related to tectonic-magmatic activity. It is the product of plate tectonic movement, continental rifts and mantle plumes or mantle hotspots in the interior of ancient continents. The emergence of indium ore deposit is inseparable from magmatic activity, especially granite magmatic activity. Ore-forming materials mainly come from the upper mantle and/or deep crust. Indium deposits formed under high temperature conditions have enrichment mechanisms. In addition to the enrichment factors of traditional metal deposits, the enrichment of nano-scale indium minerals through the nano effect is also a very important enrichment method. The indium deposits formed at the end of the differentiation and evolution of granite magma may not be enriched in one go, but is the result of multiple enrichments.

Минералого-геохимические особенности золотосодержащих руд месторождения Пакрут (Центральный Таджикистан) как основа гравитационного обогащения

The mining sector, in particular gold mining, plays an important role in the economy of Tajikistan. Today, the issue of optimizing gold mining mechanisms, increasing its efficiency and expanding the resource base is of topical importance. The depletion of easily accessible gold deposits is stimulating the development of methods for extracting gold from refractory and low-grade ores. One of the promising methods of pre-treatment of such ores is gravity enrichment. The aim of the study is to characterize the Pakrut gold deposit, to determine its mineralogical and chemical composition, and to develop an optimal gravity enrichment scheme for gold recovery. Research objectives are as follows: to study the mineralogical composition and geochemical characteristics of gold-bearing ores, and then to develop a technique for their gravitational enrichment. The object of the study is the gold-bearing ores of the Pakrut deposit (Central Tajikistan). Materials and methods of research: analytical work and enrichment in laboratory conditions were carried out in the chemical laboratory of the Pakrut Joint Venture, the ore enrichment laboratory of the V. I. Nikitin Institute of Chemistry of NANT, the Central Committee of the Main Geological Directorate under the Government of the Republic of Tajikistan. It is found that gold in the Pakrut ores is mainly represented by native gold and electrum. The main gold-bearing minerals are pyrite, arsenopyrite, sphalerite, galena, jamesonite and some vein minerals. The gold content in the ore is about 6 g/t. The granulometric composition of gold is extremely uneven. Most of the gold particles are less than 10 μm in size and are coated with gold-bearing minerals, which hindered their release during grinding. In accordance with the characteristics of the gold deposit, gravity enrichment method has been used to extract the liberated coarse gold. Studies have shown that the gravity separation process is used for the primary processing of ore to recover coarse gold particles. The gold content and recovery in the gravity separation concentrates are 46.58 g/t and 44.59 %, respectively.

Identification of Unambiguous Borrelia Peptides in Human Urine Using Affinity Capture and Mass Spectrometry.

The combination of advanced mass spectrometry and enrichment-based sample preparation methods has enhanced analytical capabilities in clinical proteomics. In this chapter, we describe a method of proteome analysis to identify Borrelia-derived peptides in urine that includes a sample affinity enrichment method coupled with liquid chromatography tandem mass spectrometry analysis and a bioinformatic peptide authentication algorithm.

Biomass waste-derived magnetic material coated with dual-dummy-template molecularly imprinted polymer for simultaneous extraction of organophosphorus and carbamate pesticides

An eco-friendly biomass waste-derived magnetic material coated with a dual-dummy-template molecularly imprinted polymer was fabricated using aqueous ethanol as a green porogen, lower amounts of toxic compounds as template molecules, and tyrosine and tryptophan as biocompatible binary monomers. The binding characteristics and selectivity of the material toward pesticides were assessed. High adsorption capacities ranging from 150.11 to 509.09 mg g−1 and imprinting factors reaching 2.2 were achieved within just 30 s. The material was applied for extraction of organophosphorus and carbamate pesticides prior to HPLC analysis. Under the optimum conditions, low limits of detection and quantitation were achieved, with ranges of 0.05–1.49 μg/L and 0.18–5.00 μg/L, respectively. The established approach enables efficient analysis of vegetable and fruit samples, yielding satisfactory recoveries ranging between 80 and 110 %. The method showed promise as an analytical method for the sensitive enrichment of pesticide residues in vegetable and fruit samples.

Carrier with cyclodextrin and quorum sensing synergy: An efficient method for selective enrichment of anammox bacteria

High-efficiency enrichment of functional bacteria is one of the biggest technical barriers to the application of anaerobic ammonium oxidation (anammox). This study combined biofilm carriers and quorum sensing to achieve rapid biomass accumulation. A biofilm carrier with biomass adsorption and quorum sensing regulation functions was developed for the rapid start-up of the reactor and enrichment of anammox bacteria (AnAOB). The nitrogen removal rates of the three reactors were further tested, and the carrier mechanism was explored. The start-up time of the reactor with the modified carriers was 28 days, which was ∼44 % shorter than that of the reactor without carriers. After 90 days of operation, the absolute abundance of total AnAOB was 3.2 times that in the control group. The modified carrier promoted the rapid adhesion of biomass through the hydrophobic cavity of cyclodextrin and induced rapid proliferation, enhancement of activity, and extracellular protein secretion of AnAOB through quorum sensing signaling molecules. Finally, a special hydrophobic biofilm with granular sludge characteristics was formed on the modified carrier through the self-assembly of hydrophobic biomass particles. Overall, we propose a novel approach to enrich anammox bacteria involving a combination of quorum sensing and biofilm carriers.

Immunoaffinity-enriched salivary small extracellular vesicles in periodontitis

Aim: Saliva extracellular vesicles (EVs) serve as a significant reservoir of biomarkers that may be of clinical use in disease diagnosis. Saliva, however, contains EVs of both host- and bacterial- origin. Identifying suitable EVs for disease diagnosis involves enriching host EVs and limiting non-host contamination with effective isolation methods. The objectives of this research were: (1) to evaluate the salivary EVs enrichment in 12 periodontally healthy patients by two different methods: size exclusion chromatography (SEC) and bead-based immunoaffinity capture (EXO-NET®); (2) to analyze the variance expression of inflammatory cytokines in EXO-NET-enriched EVs, comparing individuals with periodontitis (n = 20) to non-periodontitis (n = 12). Methods: Whole unstimulated saliva samples were collected from 12 periodontally healthy and 20 periodontitis patients. EVs were isolated from the 12 non-periodontitis patients using SEC (referred to as SEC-EVs) and EXO-NET (referred to as EXO-NET EVs), after which their total protein content, 37 EV surface markers, and bacterial pathogens expression were compared. Subsequently, the inflammatory cytokines expression levels (interleukin-IL-6, IL-1β, IL-8, and IL-10) in EXO-NET EVs were measured for non-periodontitis and periodontitis. Results: EXO-NET EVs contained more EV-specific protein and substantially higher expression of EV surface markers (CD9, CD81, CD63), but less pathogenic DNA was detected compared to that in SEC-EVs. Additionally, EXO-NET EVs from periodontitis patients contained higher amounts of IL-6 and IL-8, and decreased IL-10, compared to those from non-periodontitis patients. Conclusion: The findings suggest that immunoaffinity capture (EXO-NET) is a dependable method for salivary EVs enrichment, resulting in a higher yield of host EVs with reduced bacterial DNA detection compared to SEC. Furthermore, the research proposes that immunoaffinity capture enriched EVs can function as biomarkers for periodontitis, demonstrated by an increased expression of proinflammatory cytokines from periodontitis patients.

Characterization and chemometric based optimization of bioactive metabolites in Hypoxis hemerocallidea with the aid of UPLC-QqQ-MS/MS

β-sitosterol and solasodine are major bioactive ingredients in Hypoxis hemerocallidea (H. hemerocallidea) with significant pharmacological properties. As a result, developing a simple and efficient extraction method for simultaneous extraction of both analytes is critical. The purpose of this study was to identify and separate β-sitosterol and solasodine from ethanolic extracts of H. hemerocallidea using a modified QuEChERS method and subsequent analysis via UPLC triple quadrupole mass spectrometry. Response surface methodology was carried out, which included numerical parameters such as ultrasonication time, centrifugation time, and ultrasonication power. The categorical factors included the type of salt used to facilitate extraction, which was (NH4)2SO4 and Na2SO4. Fitting the response surface model to the experimental data produced a quadratic model with a good fit (R2 = 0.9966 for solasodine and R2 = 0.9857 for β-sitosterol). The optimum conditions for extraction of β-sitosterol and solasodine were an ultrasonication time of 30 min, ultrasonication power of 300 W and centrifugation time of 12 min. The generally higher concentrations of analytes obtained for (NH4)2SO4 indicated that it had a superior salting-out ability compared to Na2SO4. In conclusion, for the first time, β-sitosterol and solasodine were simultaneously extracted using modified QuEChERS with good yields through the salting-out action of (NH4)2SO4 in the presence of environmentally friendly solvents, ethanol and water. This modified QuEChERS technique can potentially be applied on a large scale as a sustainable and quick method for enrichment of therapeutic compounds from natural products.

Simultaneously HPLC Analysis of B1, B9 and B12 Vitamins at Trace Levels via Cloud Point Extraction

An enrichment and determination method based on liquid chromatographically analysis and cloud point extraction (CPE) has been developed for trace levels of B vitamins (B1, B9 and B12) in the proposed study. Vitamin molecules were drawn into the non-ionic surfactant phase of Polyethylene Glycol (PEG-6000) in the presence of pH 9.0 medium. The surfactant-rich phase separated by centrifugation and then dissolved with 700 µL of ethanol. The obtained ethanol phase was filtered by 0.45-micron filter prior to the HPLC analysis. All parameters affecting the CPE method such as pH, buffer volume, incubation time, surfactant and electrolyte concentration, solvent for the surfactant-rich phase and its amount have been individually studied and optimized step by step. After the optimization of all parameters of the CPE process, the detection limits of the developed method for B1, B9 and B12 vitamins were calculated as 1.42 ng mL-1, 7.14 ng mL-1 and 14.28 ng mL-1 , respectively. The linear working ranges for three vitamin molecules was obtained in the range of 5.0-500.0 ng mL-1. After CPE procedure, determination of vitamin molecules was carried out by using HPLC system with diode array detector(DAD) at 244 nm for vitamin B1, 285 nm for vitamin B9, and 361 nm for vitamin B12, respectively

An integrated method for IgG N-glycans enrichment and analysis: Understanding the role of IgG glycosylation in diabetic foot ulcer

Diabetic foot ulcer (DFU) is the most common and serious complication of diabetes, and its incidence, disability, and mortality rates are increasing worldwide. The pathogenesis of DFU is associated with dysregulated inflammation mediated by abnormal immunoglobulin G (IgG) glycosylation. In this study, we developed a comprehensive method for IgG N-linked glycosylation in the serum of DFU patients. Through analysis, we identified 31 IgG1 glycans, 32 IgG2 glycans, and 30 IgG4 glycans in the DFU serum. Furthermore, 13 IgG1 glycans, 12 IgG2 glycans, and 5 IgG4 glycans in the DFU groups were found to be significantly different from those of the control groups (p < 0.05). Of these, compared with the control group, one glycan was unique to DFU patients, and seven glycans were not detected in the DFU group. In terms of glycan characteristics, we observed a substantial decrease in galactosylation, sialylation and bisecting GlcNAcylation, and a significant increase in agalactosylation. Abnormal IgG N-glycosylation modifications were significantly associated with the chronic inflammation that is characteristic of DFU. Further, this is the first comprehensive analysis of subclass-specific IgG N-glycosylation in DFU patients, which not only fills the gap of DFU in terms of the pathological mechanisms related to IgG glycosylation but also may provide valuable clues for the immunotherapeutic pathway of DFU.

CAR-Aptamers Enable Traceless Enrichment and Monitoring of CAR-Positive Cells and Overcome Tumor Immune Escape.

Chimeric antigen receptor (CAR)-positive cell therapy, specifically with anti-CD19 CAR-T (CAR19-T) cells, achieves a high complete response during tumor treatment for hematological malignancies. Large-scale production and application of CAR-T therapy can be achieved by developing efficient and low-cost enrichment methods for CAR-T cells, expansion monitoring in vivo, and overcoming tumor escape. Here, novel CAR-specific binding aptamers (CAR-ap) to traceless sort CAR-positive cells and obtain a high positive rate of CAR19-T cells is identified. Additionally, CAR-ap-enriched CAR19-T cells exhibit similar antitumor capacity as CAR-ab (anti-CAR antibody)-enriched CAR-T cells. Moreover, CAR-ap accurately monitors the expansion of CAR19-T cells in vivo and predicts the prognosis of CAR-T treatment. Essentially, a novel class of stable CAR-ap-based bispecific circular aptamers (CAR-bc-ap) is constructed by linking CAR-ap with a tumor surface antigen (TSA): protein tyrosine kinase 7 (PTK7) binding aptamer Sgc8. These CAR-bc-aps significantly enhance antitumor cytotoxicity with a loss of target antigens by retargeting CAR-T cells to the tumor in vitro and in vivo. Overall, novel CAR-aptamers are screened for traceless enrichment, monitoring of CAR-positive cells, and overcoming tumor cell immune escape. This provides a low-cost and high-throughput approach for CAR-positive cell-based immunotherapy.

Simplification of the pretreatment method for phosphate oxygen isotope measurement in phosphogypsum leachate

The stacking of phosphogypsum has caused considerable phosphorus pollution in water bodies near phosphogypsum yards through surface runoff and underground infiltration. The phosphate oxygen isotope (δ18Op) tracing method has served as a valuable tool for tracing phosphorus pollution in water. However, the existing δ18Op enrichment and purification methods are complex, costly, and inefficient for phosphate recovery, particularly for phosphogypsum leachate with complex compositions. Herein, a simplified and optimized pretreatment method for δ18Op measurement in phosphogypsum leachate was developed. Zirconium/polyvinyl alcohol (Zr/PVA) gel beads showed good selectivity for phosphate enrichment from water at different initial phosphate concentrations with appropriate Zr/PVA dosage. The optimal enrichment pH value was <7, and the concentrated phosphate on the Zr/PVA gel beads could be effectively eluted in an alkaline environment. Compared with the traditional Fe or Mg coprecipitation enrichment methods, impurities in the solution showed no obvious adverse effects on the phosphate enrichment process. Further, the phosphate solution eluted from the Zr/PVA gel beads was purified by a simple adjustment of the pH instead of cation exchange in the traditional purification process. Magnesium ions in the solution could be completely removed when the pH ranged from 3.17 to 6.15, and the phosphate recovery rate could reach 98.66% when the eluent pH was 5.02. Fourier-transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy revealed that similar to traditional pretreatment method, the proposed method can obtain high-purity Ag3PO4 solids for δ18OP measurement and no isotope fractionation of δ18OP was observed. Therefore, this study provides a promising and reliable pretreatment method for δ18OP measurement, especially in complex phosphogypsum leachate.

Ultrasensitive detection of circulating tumor cells in clinical blood samples by a three-dimensional network nanovehicle-based aptasensor platform

A burgeoning topic in the early diagnosis and treatment of cancer is the sensitive and precise quantification of circulating tumor cells (CTCs). However, due to the extremely low CTC concentrations in the blood, traditional enrichment and identification methods for CTCs are prone to false negative results. Here, to specifically identify and improve the sensitivity of CTC detection in the blood, we designed a novel fluorometric turn-on aptasensor platform based on a three-dimensional network nanovehicle (TDNN) modified with a PEG derivative and AS1411 aptamer specifically targeting the nucleolin protein. The limit of detection (LOD) of the aptasensor platform was as low as 2 cells per mL, which was remarkably better than that of the single nanoparticle ASS1. Notably, the novel aptasensor platform showed excellent specificity and sensitivity as well as negligible fluorescent background for quantitative and visualization detection of CTCs in peripheral blood samples without enrichment, centrifugation and washing steps. More importantly, the number of CTCs identified by TDNN was significantly higher in metastatic patients than in nonmetastatic patients, while CTCs were not detected in the blood samples of healthy donors. In conclusion, the aptasensor platform provides an available and promising tool for CTC identification and cancer metastasis prediction in clinical blood samples.

Envelope enrichment method for homogenization of non-periodic structures

The homogenization of composite materials is critical for accurately predicting their mechanical performance, particularly when complex reinforcement arrangements are involved. Microstructural characteristics exert a substantial influence on the composite’s properties during practical applications. A widely adopted approach for analyzing composites is the numerical simulation of a Representative Volume Element (RVE). Although this method is well-established for periodic RVEs, it encounters difficulties when applied to non-periodic meshes, which complicates the imposition of classical boundary conditions on nodes exhibiting varying properties. To address this challenge, we propose a novel methodology that involves modeling an envelope surrounding the RVE, to which periodic boundary conditions are applied. By defining the envelope as a homogeneous material, stress transmission to the RVE is facilitated. The stiffness tensor of the envelope is updated iteratively through a homogenization process, ultimately converging to the effective properties of the RVE. The method is validated on a non-periodic arrangement of spherical inclusions embedded within a matrix. Convergence is observed in the different cases studied within ten iterations and the results are found within the Voigt and Reuss bound.

A study on speciation and enrichment of rare earth elements (REE) by sequential extraction from a potential coal fly ash resource and its role in REE extractability

Coal fly ash (CFA) is a potential secondary Rare Earth Element (REE) source that needs an efficient enrichment and extraction process. Annually, coal-fired power plants generate nearly 1 billion tonnes of coal ash. India alone produced 270.82 million tonnes of CFA in 2021–22. The average global concentration of REE in coal ash is 403.5 mg/kg. The present authors have already studied some promising CFAs from Indian thermal power stations and one such CFA is used in the present study for the sequential extraction (SE), speciation, and enrichment of REEs. Organic acids are used for SE to determine different fractions of REEs and it is found that REEs are mostly associated with amorphous Mn-oxide and organic and sulfide fractions. About 84% of REEs are in the glassy phase that SE cannot dissolve. The main components of CFA and SE residues are quartz, mullite, and glassy phase (52.0–59.2%). The XRF analysis showed that CFA is ‘Class F' (ASTM C618–19). The ESEM – EDS and backscatter imaging revealed monazite-(La) mineral as the REE carrier in CFA. Furthermore, enrichment studies using acid and alkali media have been performed. Alkali treatment with NaOH and KOH increased total REE by 1.61 and 1.32 times, respectively. Acidic treatment with HCl and oxalic acid increased total REE by 1.27 and 1.09 times, respectively. Therefore, NaOH followed by HCl treatment could be a cost-effective and sustainable REE enrichment and extraction method from CFA.