Dissolution Method Research Articles

Overcoming drug impurity challenges in amorphous solid dispersion with rational development of biorelevant dissolution-permeation method

Hot-melt extrusion is often used to prepare amorphous solid dispersion to overcome low drug solubility and enhance bio-performance of the formulation. Due to the uniqueness of each drug – polymer combination and its physico-chemical properties, setting the appropriate HME barrel temperature, feed rate and screw speed ensures drug amorphization, absence of residual crystallinity, absence of water, and a suitable drug release profile. In this research, samples with BCS II/IV model drug and PVP/VA polymer were prepared to evaluate the impact of HME process parameters, incoming drug form (anhydrous vs. hydrate), and drug supplier (i.e., impurity profile), on biorelevant drug release. This study provides a relationship between observed in vitro supersaturation and precipitation behavior of amorphous solid dispersion formulation with in vivo results, on patients, by using the acceptor profile of side-by-side dissolution-permeation apparatus.An in vitro dissolution method, in small volumes, in an apparatus with paddles and dissolution-permeation side-by-side method was developed on the MicroFlux™ apparatus to assess if the differences observed in vitro bears relevance to the bioequivalence outcome in vivo. The former was used to guide the generic drug product development due to high discriminatory strength, while the latter was biorelevant, due to the inclusion of the second compartment assuring absorptive environment to capture the impact of supersaturation and subsequent precipitation on bioavailability. Bio-relevancy of the in vitro method was confirmed with the in vivo dog study and clinical study on patients, and an in vitro – in vivo correlation was established.For the investigated BCS II/IV drug, this research highlights the importance of considering supersaturation and formation of colloidal species during amorphous solid dispersion release testing to assure product quality, safety and efficacy.

Retrospective analysis of the biopharmaceutics characteristics of solid oral Modified-Release drug products in approved US FDA NDAs designated as Extended-Release or Delayed-Release formulations

BackgroundModified Release (MR) orally administered drugs products [Extended-Release (ER) and Delayed-Release (DR)] differ from Immediate-Release (IR) drug products in their drug release site and/or rate to offer therapeutic advantages. It is important to understand the biopharmaceutics factors that determine how a drug works in the gastrointestinal tract and the various pharmacokinetic properties that determine a drug’s rate of absorption and release in the human body. To better understand the biopharmaceutics characteristics of ER and DR drug products, this study retrospectively analyzed submissions approved by the US Food and Drug Administration (FDA), from 2001 to 2021, and their corresponding review documents. This review work is expected to enhance the readers’ understanding regarding the biopharmaceutics properties that supported approval of these products’ ER claims, as per 21 CFR 320.25(f), and DR claims. MethodsA comprehensive search was conducted using the FDA’s internal New Drug Application (NDA) database for ER and DR oral drug products approved between 2001 and 2021. The search yielded 87 ER applications (23 ER capsules and 64 ER tablets) and 21 DR applications (10 DR capsules, 11 DR tablets) for which electronic records were accessible. These products were analyzed for overall drug product design, dosing frequency compared to the reference (if applicable), degree of fluctuation, dissolution method, and alcohol dose-dumping. ResultsOut of 87 total applications for ER drug products that were assessed, 62% of the ER tablets contained a polymer matrix formulation, and hypromellose (HPMC) was used in 50% of these products. 52% of the ER capsules consisted of polymer beads while about half of the DR drug products contained a non-bead formulation with a combination of polymers. The majority of ER drug products were found to have a reduction in dosing frequency and a decrease in the degree of fluctuation when compared to the IR reference product. The 13 ER drug products that exhibited an increase in degree of fluctuation exhibited general and pharmacodynamic benefits, such as reduced dosing frequency and reduced pill burden. The majority of DR formulations were developed to prevent drug degradation in the stomach, followed by to decrease potential stomach irritation, and lastly for localized release in the colon. The majority of ER drug products had 1:1 ratios of dissolution duration compared to dosing frequency (i.e., the majority of ER drug products had a dissolution duration of 24 h and were dosed every 24 h while those with a dissolution duration of 12 h were dosed every 12 h). The majority of ER applications had single-stage dissolution methods while most DR drug products used biphasic dissolution methods. All of the DR dissolution methods incorporated an acid stage of 2 h and a buffer stage with various timeframes. 53% the DR drug products had a ratio of dissolution duration to dosing frequency of 1:4 (e.g. a dissolution duration of 2 h to a dosing frequency of 8 h) or 1:8 (e.g. a dissolution duration of 2 h to a dosing frequency of 16 h). Of the ER tablets and DR drug products, 72% exhibited no alcohol dose-dumping under in vitro testing conditions. ER capsules, however, did not yield similar results—most of which exhibited alcohol induced dose-dumping. Alcohol dose dumping was mitigated by either in vivo studies or warnings on the drug product label. ConclusionThe results of this study help the reader understand the design, characteristics, and pharmacological advantages of the ER and DR drug products for patient benefit; as well as the regulations governing the FDA’s assessment of ER claims.

The step-wise dissolution method: An efficient DSC-based protocol for verification of predicted API–polymer compatibility

The development of an amorphous solid dispersion (ASD) is a promising strategy for improving the low bioavailability of many poorly water-soluble active pharmaceutical ingredients (APIs). The construction of a temperature–composition (T–C) phase diagram for an API–polymer combination is imperative as it can provide critical information that is essential for formulating stable ASDs. However, the currently followed differential scanning calorimetry (DSC)-based strategies for API solubility determination in a polymer at elevated temperatures are inefficient and, on occasions, unreliable, which may lead to an inaccurate prediction at lower temperatures of interest (i.e., T = 25 °C). Recently, we proposed a novel DSC-based protocol called the “step-wise dissolution” (S-WD) method, which is both cost- and time-effective. The objective of this study was to test the applicability of the S-WD method regarding expeditious verification of the purely-predicted API–polymer compatibility via the perturbed chain-statistical associating fluid theory (PC-SAFT) equation of state (EOS). Fifteen API–polymer T–C phase diagrams were reliably constructed, with three distinct API–polymer case types being identified regarding the approach used for the S-WD method. Overall, the PC-SAFT EOS provided satisfactory qualitative descriptions of the API–polymer compatibility, but not necessarily accurate quantitative predictions of the API solubility in the polymer at T = 25 °C. The S-WD method was subsequently modified and an optimal protocol was proposed, which can significantly reduce the required experimental effort.

Highly efficient dissolution and reinforcement mechanism of robust and transparent cellulose films for smart packaging

The packaging of fresh foods increasingly focuses on renewable and eco-friendly cellulose films, but their low dissolution efficiency and weak mechanical strength greatly limit their wide application, which also cannot be used for smart packaging. Here, a highly efficient synergistic chloride-salt dissolution method was proposed to fabricate robust, transparent, and smart cellulose films. Cellulose films with appropriate Ca2+ concentration exhibited robust mechanical strength, better thermal stability, high transparency and crystallinity. The metal chelation of Ca2+ with cellulose chains could induce cellulose chain arrangement during the cellulose regeneration process. Particularly, compared to pure cellulose films, the tensile strength and elongation at break of cellulose films with suitable Ca2+ were increased by 167 % and 200 %, respectively. Moreover, optimal cellulose films can be used to reflect the quality of the fruit by detecting changes in ethanol gas. Hence, a novel strategy is presented to fabricate robust and transparent cellulose films with great potential application for smart packaging.

Effective Leaching of Argillaceous and Dolomitic Carbonate Rocks for Strontium Isotope Stratigraphy

Various methods have been developed to extract a primary seawater Sr isotope signal from carbonate rocks for strontium isotope stratigraphy. However, there is little consensus around the best method due to variable sample purity and mineralogy. For this study, we applied sequential leaching to a range of rock samples in order to explore strontium isotope leaching systematics of less favoured argillaceous and dolomitic limestone samples. Following an ammonium acetate (NH4Ac) prewash that removed ~ 10% of the carbonate fraction, a subsequent dilute acetic acid leach (10–30% aliquot) was shown to extract the lowest, demonstrably least altered seawater 87Sr/86Sr isotope ratios, along with in most cases seawater‐like rare earth element (REE) plus yttrium (Y) patterns with the highest Y/Ho ratios (mostly > 36). Subsequent dissolution steps exhibited significantly elevated 87Sr/86Sr isotope ratios, Rb/Sr, Al/Ca and Mg/Ca ratios, indicating greater contributions from aluminosilicates and dolomite in the leachates. The new dissolution method by comparison significantly increases the likelihood of obtaining primary seawater 87Sr/86Sr isotope ratios from argillaceous and dolomitic limestones where the other established procedures failed. Broad application of this approach could improve the temporal resolution of the seawater Sr isotope curve, especially where high purity limestone samples are scarce.

A Review on Dissolution Method Development for Drug Products: Current Regulations and Prospects

Dissolution (in vitro release) testing has been the subject of intense scientific and regulatory interest over the past several decades. As an analytical methodology, in vitro dissolution testing measures drug release into the dissolution media. The U. S. Food and Drug Administration (USFDA) Dissolution Database was reviewed and screened regarding the type of dosage forms, apparatus type, agitation speed, media volume, and recommended time points for the dissolution profile. The dissolution method requires special laboratory equipment, following a well-defined protocol. Basic information is available in the United States Pharmacopeia general chapters<711> Dissolution, <724> Drug Release, and <1092> The Dissolution Procedure – Development and Validation and these chapters were used as a starting point for this revision. The article describes current regulatory expectations for establishing a suitable dissolution method for implementing quality control tools, a way to maintain lot quality and consistency between development batches and post-approval commercial batches. Dissolution methods draw offers some advantages as a possible surrogate for extensive clinical studies in certain cases required after scale-up and post-approval changes in the product's life cycle and serves as an essential tool for establishing waivers for filing of lower strengths of the drug product. The step-by-step dissolution method development plan as per current regulatory perspectives and the factors to be considered are explained with examples. Scientist requires detailed insights on the selection of media and volumes, physicochemical properties of active substance, sink condition, type of enzymes, selection of apparatus, deaeration, sinkers, agitation speed, and time point’s measures. The advanced dissolution method is evaluated against its discriminatory power by intentionally varying formulation and process variables

Green and efficient utilization of beech sawdust waste for sorbitol production: Direct conversion residue via Ru2P/OMC derived from separated lignin

This paper proposes a green and sustainable strategy to achieve efficient utilization of beech sawdust waste to produce sorbitol. First, ethanol dissolution method was used to extract lignin from sawdust. Subsequently, the lignin combined with phloroglucinol were used to fabricate ordered mesoporous carbon (OMC) using solvent evaporation induced self-assembly (EISA) method. Afterwards, Ru2P/OMC was synthesized and utilized as a catalyst for the production of sorbitol from the residue using pure water as green solvent. Finally, the yield of sorbitol and xylitol reached 77.2 % and 12.5 % at 200 °C in 5 h, respectively. Different characterization techniques were used to reveal the structural composition of the catalysts and the mechanism of the reaction. The results show that the bifunctional Ru2P/OMC catalyst has dual activity of hydrolysis and hydrogenation without sulfonation treatments. Interestingly, the bifunctional Ru2P/OMC catalyst has satisfactory activity, selectivity, and stability, which is promising in biomass waste conversion.

Experimental design for novel in-vitro dissolution method validation for lamivudine-150mg and zidovudine-300mg film-coated tablets

Experimental design for novel in-vitro dissolution method validation for lamivudine-150mg and zidovudine-300mg film-coated tablets

Multi-scale study of turbulent mass transfer process in different shaped-adsorbent packed bed

Insufficient consideration of the coupled effect of multi-scale and turbulent mass transfer impedes thorough understanding of the dynamic adsorption process in the fixed bed. To solve this problem, a novel PR-CMT model, integrated particle resolution method and computational mass transfer theory, is proposed and verified to simulate the gas adsorption process on particles by combining the computational mass transfer method and the particle dissolution method. The proposed model not only rigorously accounts for the turbulent diffusion by incorporating the equation of concentration variance c2‾ and concentration variance dissipation εc, but also establishes connections between different scales of fixed-bed particle-fluid systems. Through this work, it is found that there is a preferred fluid path in the particle filling structure, which can lead to significant changes in local mass transfer performance. Additionally, the turbulent diffusion enhances the mass and heat transfer between the gas and particles, resulting in a more uniform distribution in the radial direction. Using the proposed model, the effects of the adsorbent characteristics on the multi-scale adsorption process, such as the adsorbent porosity and shape, are further examined. The results indicate that increasing the adsorbent porosity leads to enhanced overall adsorption rate in the fixed bed, and the turbulent diffusion is strongest in the fixed bed with cylinder adsorbents.

Flurbiprofen cataplasms: Development and validation of in-vitro dissolution methods and evaluation of multimedia dissolution profiles

The investigation of the systemic release performance of dosage forms using in vitro tools is a crucial objective in the realm of pharmaceutical development. The dissolution methodology is an effective tool for monitoring batch-to-batch variabilities in quality control and gaining insight into the release mechanisms of pharmaceutical drugs. The majority of the dissolution techniques that have been approved are primarily intended for solid oral dosage forms. Nevertheless, these techniques have also been applied to various other dosage forms, including transdermal drug delivery systems. The administration of medication through cataplasm, a transdermal application, poses challenges in understanding the characteristics of drug release. Flurbiprofen is classified as a class II drug according to the Biopharmaceutics Classification System and is commonly administered in the form of a cataplasm for its analgesic properties. A dissolution method was developed to assess the in vitro release profile of the flurbiprofen transdermal delivery system. This method utilized a United States Pharmacopeia dissolution apparatus V, with a disc assembled over the paddle. Additionally, a method for quantification was developed using liquid chromatography. The discriminatory aspect of the developed method has faced criticism due to substantial alterations in excipient composition. Furthermore, we have developed clearly defined multimedia release profiles within the physiological pH range. The validation of the dissolution and chromatography systems was conducted.

Uptake of Silver-Containing Nanoparticles in an Estuarine Plant: Speciation and Bioaccumulation.

Understanding the bioaccumulation of silver-containing nanoparticles (Ag-NPs) with different species, concentrations, and sizes in estuarine plants is critical to their related environmental risk. Herein, the distribution of Ag-NPs in tidewater, sediments, and plants (Scirpus triqueter) of field-constructed mesocosm was investigated, where tidewater was exposed to Ag0-NPs and Ag+ at environmentally relevant concentrations. Particle number concentrations (PNCs) and sizes of Ag-NPs with various species were analyzed using a multistep selective dissolution method followed by the single-particle- inductively coupled plasma mass spectrometry technique. After 30 days of exposure, more than half of Ag0-NPs were dissolved to Ag+ and about 1/4 of Ag+ were transformed into Ag0-/AgCl-NPs in tidewater. Ag-NPs in stems exposed to Ag0-NPs were found to be dominated by metallic Ag, while Ag+ exposure led to more Ag2S-NPs in stems. In roots, 71% and 51% of Ag-NPs were found as Ag2S-NPs for Ag0-NPs and Ag+ treatment groups, respectively. Plant stems had a significantly higher enrichment of Ag-NPs than roots. Based on both random forests and structure equation models, it is suggested that salinity of tidewater can regulate Ag0-NPs in tidewater indirectly by influencing AgCl-NPs in tidewater and further affect the total PNCs of Ag-NPs in plant stems. Moreover, elevated sulfate-reducing bacteria (SRB) result in more Ag2S-NPs in rhizosphere sediments, thereby enhancing the bioaccumulation of Ag-NPs by roots.

Novel Biphasic In Vitro Dissolution Method Correctly Predicts the Oral Bioavailability of Curcumin in Humans.

In vitro dissolution methods correctly predicting in vivo bioavailability of compounds from complex mixtures are lacking. We therefore used data on the in vivo performance of bioavailability-improved curcumin formulations to implement an in vivo predictive dissolution method (BiPHa+). BiPHa+ was applied for the characterization of eight curcumin formulations previously studied in a strictly controlled pharmacokinetic human trial. During dissolution, the dissolved proportion of curcumin in the aqueous medium underwent a formulation-dependent reduction, whereas the proportion remained stable in the organic layer. Compared with conventional dissolution systems, BiPHa+ was superior in terms of in vivo-relevant formulation characterization. All formulations could be precisely categorized according to their bioavailability in humans. In vitro-in vivo relationships for each dissolution method were established, with BiPHa+ providing the highest degree of linearity (r2 = 0.9975). The BiPHa+ assay correctly predicted the bioavailability of curcuminoids from complex mixtures and provided mechanistic information about formulation-dependent release characteristics.

Study of alkali-soluble curdlan/bacterial cellulose/cinnamon essential oil blend films with enhanced mechanical properties

In response to the growing demand for biodegraded film with high mechanical properties for complex preservation application scenarios, we developed a curdlan (CD) blended films with exceptional mechanical strength through an alkali dissolution method. Notably, the alkali-soluble CD film exhibited five-fold increase in tensile strength (TS) when compared to its water-soluble counterpart. Furthermore, the inclusion of 2 % bacterial cellulose (BC) resulted in a significant 41.1 % augmentation of the film's TS. Thermal stability improvements were observed through differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA). X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) results provided insights into alterations in film crystallinity and intermolecular interactions. Specifically, the incorporation of 10 % CEO led to an additional improvement in TS. Our experimental investigations involving the packaging of chilled fresh meat with these blended films unveiled their capacity to effectively inhibit microorganism growth, maintain meat color stability, delay protein decomposition and fat oxidation, and extend the storage time up to 9 days. Our study offers a promising solution for food packaging, emphasizing the development of a high-strength degradable CD/BC/CEO blended film, which holds potential for extending the shelf life of food products.

Building a bimodal landscape: bedrock lithology and bed thickness controls on the morphology of Last Chance Canyon, New Mexico, USA

Abstract. We explore how rock properties and channel morphology vary with rock type in Last Chance Canyon, Guadalupe Mountains, New Mexico, USA. The rocks here are composed of horizontally to near-horizontally interbedded carbonate and sandstone. This study focuses on first- and second-order channel sections, where the streams have a lower channel steepness index (ksn) upstream and transition to higher ksn values downstream. We hypothesize that differences in bed thickness and rock strength influence ksn values, both locally by influencing bulk bedrock strength and also nonlocally through the production of coarse sediment. We collected discontinuity intensity data (the length of bedding planes and fractures per unit area), Schmidt hammer rebound measurements, and measured the largest boulder at every 12.2 m elevation contour to test this hypothesis. Bedrock and boulder mineralogy were determined using a lab-based carbonate dissolution method. High-resolution orthomosaics and digital surface models (DSMs) were generated from drone and ground-based photogrammetry. The orthomosaics were used to map channel sections with exposed bedrock. The United States Geological Survey (USGS) 10 m digital elevation models (DEMs) were used to measure channel slope and hillslope relief. We find that discontinuity intensity is negatively correlated with Schmidt hammer rebound values in sandstone bedrock. Channel steepness tends to be higher where reaches are primarily incising through more thickly bedded carbonate bedrock and lower where more thinly bedded sandstone is exposed. Bedrock properties also influence channel morphology indirectly, through coarse sediment input from adjacent hillslopes. Thickly bedded rock layers on hillslopes erode to contribute larger colluvial sediment to adjacent channels, and these reaches have higher ksn values. Larger and more competent carbonate sediment armors both the carbonate and the more erodible sandstone and reduces steepness contrasts across rock types. We interpret that in the relatively steep, high-level ksn downstream channel sections, the slope is primarily controlled by the coarse alluvial cover. We further posit that the upstream low-level ksn reaches have a base level that is fixed by the steep downstream reaches, resulting in a stable configuration, where channel slopes have adjusted to lithologic differences and/or sediment armor.

Application of Thermodynamic Models to Predict the Solubility of Biologically Active Substances

Introduction. The choice of solvents for the processes of extraction of biologically active substances from natural raw materials, the processes of purification of natural and synthesized substances by extraction, crystallization and dissolution methods is an important problem of the modern pharmaceutical industry, because a large number of experiments must be performed to determine the optimal solvent or mixture of solvents. To reduce the cost of developing and optimizing the extraction and purification of substances stages, it is proposed to use thermodynamic models at the stage of preliminary solubility assessment. The article investigates predicting the solubility of pharmaceutical substances issue on the example of the technology for isolating hesperidin and glycyrrhizic acid from plant materials.Aim. Theoretical determination of the dissolving power of various solvents with respect to hesperidin and glycyrrhizic acid.Materials and methods. The PMUNIFAC and NRTL-SAC thermodynamic models were used to predict solubility. The solubility calculation for the NRTL-SAC model was performed using Aspen Properties V14 software, and for the PMUNIFAC model using PTC Mathcad Prime V6. To evaluate the results obtained using thermodynamic models, a number of experiments were carried out, the object of which was the peel of an orange (dried flavedo and albedo, the degree of grinding is 0.2–0.5 mm, the moisture content is 8 %). The quantitative content of hesperidin was determined by direct spectrophotometry at a wavelength of 290 nm. Statistical data processing was performed using Minitab v20 software (Minitab Inc., USA), differences were considered statistically significant at p < 0.05.Results and discussion. On the basis of thermodynamic models, the prediction of the solubility of hesperidin and glycyrrhizic acid was made. It has been shown that the solubility can be assessed both in the presence of solubility data according to the NRTL-SAC model, and in their complete absence according to PMUNIFAC. The correspondence of the theoretically calculated data to the experimental data confirms the correctness of the calculations of thermodynamic models. The results of the calculations are evaluated and solvents are recommended that can be used in the technology of isolating hesperidin and glycyrrhizic for the stages of degreasing, extraction and crystallization with the antisolvent.Conclusion. Using the NRTL-SAC and PMUNIFAC thermodynamic models, the dissolving power of various solvents with respect to hesperidin and glycyrrhizic acid was determined. From the calculation results, a list of solvents was built, ranked by the solubility of the studied substances in them. The resulting list can be used in the development of an industrial technology for the isolation and purification of hesperidin and glycyrrhizic acid. It is shown that the NRTL-SAC and PMUNIFAC models have good prospects for quantitative prediction of the solubility of active substances.

Comparison of residual carbon content and morphology of B4C powders synthesized under different conditions

In this article, the impact of different B4C synthesis methods on the amount of residual carbon and the final morphology of the prepared ceramic particles was investigated. The main materials for the synthesis of B4C were glucose and boric acid, and the effects of adding tartaric acid and performing mechanical activation were studied. For this purpose, two methods of carbon dissolution and boron carbide oxidation were used to determine the amount of residual carbon in the ceramic products. The results of the investigations on the sample synthesized in optimal conditions showed that if additives and mechanical activation are not used, about 7 wt% of carbon will remain in the synthesized powder. The amount of carbon decreased to 5.7 wt% with mechanical activation, but the best result was obtained with the addition of tartaric acid, in which the amount of impurity dropped to 3.3 wt%. Finally, the size and morphology of B4C particles and carbon impurities were observed and compared using a scanning electron microscope.

A Correlative Dissolution Study of Oral Drug Delivery Systems through Reverse Phase-HPLC Analysis

Oral drug administration is essential for treating diverse diseases due to its acceptable route, non-invasiveness, minimal off-target side effects, versatility, and painless patient delivery. However, multiple drug accessibility is increasing currently but there is often a deficiency of indication in developing procedures with assessment of two diverse medicinal formulations. Oral administration of a novel antiepileptic drug, levetiracetam in grouping with either L-dopa unaccompanied or L-dopa/Ropinirole treatments was associated with dyskinesia. Altered shooting patterns of neurons relating to a compulsive harmonization process may back to the origin of dyskinesia. The current study aims to develop a dissolution technique and validate the antiparkinsonian drug-ropinirole and antiepileptic drug-levetiracetam tablets by RP-HPLC, which plays a major part in pharmaceutical formulations. The optimal dissolution conditions were experienced for the products respective to the pharmaceutical formulation and applied to assess the dissolution profiles. Ideal settings for the dissolution method were 500 mL of pH of 4.0 citrate buffer, 50 rpm and 250 nm for ropinirole tablets and 900 mL of distilled water, the rotation speed of paddle 50 rpm and 217 nm for levetiracetam tablets, then 3.84 and 3.87 minutes were set as the retention time of ropinirole and levetiracetam tablets, respectively. Technique optimization and validation process helps to reduce the bioequivalence of both dosage forms. The current study ensues detailed information on the drug release, even if there is a change in pH medium, filter, rpm, instrumentation, etc. Focusing on current pharmaceutical sciences, the proposed correlative dissolution study coupled with RP-HPLC analysis could offer a holistic insight into the performance of future oral drug delivery systems

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.

Determining the Phase Composition of Copper Ferrite Samples by a Standardless Differential Dissolution Method

Determining the Phase Composition of Copper Ferrite Samples by a Standardless Differential Dissolution Method

Muscle supercompensation inspired high-strength partially dissolved-regenerated cellulose biochar as the matrix of phase change materials for thermal storage

Balsa wood is widely planted as a light wood and easily available. However, the low strength of balsa wood limits its application scenarios. Based on the concept of muscle supercompensation, we reported cellulose partial dissolution and regeneration methods of wood to synthesize high strength matrix for preparation of efficient shape-stable phase change materials (ss-PCMs). Notably, part of the cellulose of the balsa wood was deconstructed, and a nano-scale entangled regenerated cellulose structure was formed in ethanol. The obtained carbonized cellulose regeneration wood (CRW) shows a hierarchically porous network with high mechanical strength and the specific surface area of CRW was around 17 times higher than that of natural balsa wood. The CRW exhibited high adsorption capacity for tetradecanoic acid (TA), and the maximum content of TA adsorbed in CRW was calculated to be 90.3%. Moreover, the CRW based ss-PCMs (CRPs), prepared by using CRW as carrier and TA as core material, can effectively improve the photo-thermal conversion efficiency of CRPs to 83.6%. This “wood supercompensation” strategy has the merits of simple and degradability, which provides a new approach for the recycle of lignocellulose and a promising way for the production of ss-PCM with high strength and excellent energy storage capacity.