4,065 results match your criteria dissolution mechanism


Internal loading of phosphate in rivers reduces at higher flow velocity and is reduced by iron rich sand application: an experimental study in flumes.

Water Res 2021 Apr 18;198:117160. Epub 2021 Apr 18.

Division of Soil and Water Management, Department of Earth and Environmental Sciences, KU Leuven, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven, Belgium.

Many lowland regions are afflicted with high phosphorus (P) peaks in rivers during the summer months. Static incubations of sediments have shown that reductive dissolution of ferric iron (Fe(III)) minerals in the sediment explain these P peaks. This study was set up to identify if that mechanism also dominates in a dynamic system, thereby testing the roles of water flow velocity and sediment Fe/P ratio. Read More

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Revealing the Structure Evolution of Heterogeneous Pd Catalyst in Suzuki Reaction via the Identical Location Transmission Electron Microscopy.

ACS Nano 2021 May 7. Epub 2021 May 7.

Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.

The mechanism of palladium nanoparticles (Pd NPs)-catalyzed cross-coupling reactions has been the subject of intense debate since the recognition of catalytic active sites involving a wide array of dynamic changed Pd species. Here, through the combination of the hot filtration experiment together with the recently developed identical location transmission electron microscopy (IL-TEM) method, the delicate structure evolution of highly dispersed Pd NPs supported on oxygen-functionalized carbon nanotubes (Pd/oCNTs) as well as the kinetics properties of derived dissolved species in liquid phase were systemically investigated in the Suzuki-Miyaura reaction. The result indicates that the leached Pd components caused by the strong adsorption of reactants might have a significant contribution to the coupling products, and the degree for different substrates follows the order of iodobenzene > phenylboronic acid > bromobenzene. Read More

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Improved antibacterial activity of hemp fibre by covalent grafting of quaternary ammonium groups.

R Soc Open Sci 2021 Mar 24;8(3):201904. Epub 2021 Mar 24.

Institute of Bast Fibre Crops, Chinese Academy of Agricultural Sciences, 410205 Changsha, Hunan, People's Republic of China.

In this study, a novel antibacterial hemp fibre grafted with quaternary ammonium groups (HF-GTA), were prepared by alkalization, oxidation, amination and quaternization multistage reactions. The chemical structure and micromorphology of the fibre were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and X-ray diffraction. The grafting and reaction mechanism proved to be successful, which indicated that the grafting reaction primarily occurred on the hydroxyl group of cellulose and hemicellulose in the hemp fibre, where it retained good fibrous morphology, thermal stability and hygroscopicity. Read More

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Effects of porosity on drug release kinetics of swellable and erodible porous pharmaceutical solid dosage forms fabricated by hot melt droplet deposition 3D printing.

Int J Pharm 2021 Apr 29:120626. Epub 2021 Apr 29.

School of Pharmacy, University of East Anglia, Norwich, NR4 7TJ, United Kingdom. Electronic address:

3D printing has the unique ability to produce porous pharmaceutical solid dosage forms on-demand. Although using porosity to alter drug release kinetics has been proposed in the literature, the effects of porosity on the swellable and erodible porous solid dosage forms have not been explored. This study used a model formulation containing hypromellose acetate succinate (HPMCAS), polyethylene oxide (PEO) and paracetamol and a newly developed hot melt droplet deposition 3D printing method, Arburg plastic free-forming (APF), to examine the porosity effects on in vitro drug release. Read More

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Formation and growth mechanism for niobium oxide nanoparticles: atomistic insight from in situ X-ray total scattering.

Nanoscale 2021 May 23;13(17):8087-8097. Epub 2021 Mar 23.

Department of Chemistry and Nano-Science Center, University of Copenhagen, 2100 Copenhagen Ø, Denmark.

Understanding the mechanisms for nanoparticle nucleation and growth is crucial for the development of tailormade nanomaterials. Here, we use X-ray total scattering and Pair Distribution Function analysis to follow the formation and growth of niobium oxide nanoparticles. We study the solvothermal synthesis from niobium chloride in benzyl alcohol, and through investigations of the influence of reaction temperature, a formation pathway can be suggested. Read More

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Effect of Fe-Mn-La-modified biochar composites on arsenic volatilization in flooded paddy soil.

Environ Sci Pollut Res Int 2021 May 4. Epub 2021 May 4.

Department of Civil and Environmental Engineering, Shantou University, Shantou, 515063, China.

As can be volatilized naturally; however, this has adverse environmental effects. In this study, we investigated As volatilization in flooded paddy soil with the addition of biochar (BC) and Fe-Mn-La-modified BC composites (FMLBCs). The addition of BC and FMLBCs caused decreases in total As volatilization in the soil over 7 weeks. Read More

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The mechanism of contaminant removal in Fe(0)/HO systems: The burden of a poor literature review.

Chemosphere 2021 Apr 27;280:130614. Epub 2021 Apr 27.

Department of Applied Geology, University of Göttingen, Goldschmidtstraße 3, D-37077, Göttingen, Germany; Centre for Modern Indian Studies (CeMIS), Universität Göttingen, Waldweg 26, 37073, Göttingen, Germany; Department of Water and Environmental Science and Engineering, Nelson Mandela African Institution of Science and Technology, P.O. Box 447, Arusha, Tanzania; Faculty of Science and Technology, Campus of Banekane, Université des Montagnes, P.O. Box 208, Bangangté, Cameroon. Electronic address:

The global effort to mitigate the impact of environmental pollution has led to the use of various types of metallic iron (Fe(0)) in the remediation of soil and groundwater as well as in the treatment of industrial and municipal effluents. During the past three decades, hundreds of scientific publications have controversially discussed the mechanism of contaminant removal in Fe(0)/HO systems, with the large majority considering Fe(0) to be oxidized by contaminants of concern. This view assumes that contaminant reduction is the cathodic reaction occurring simultaneously with Fe oxidative dissolution (anodic reaction). Read More

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Decontamination of radioactive cesium-contaminated soil/concrete with washing and washing supernatant- critical review.

Chemosphere 2021 Apr 26;280:130419. Epub 2021 Apr 26.

Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-ro, Seoul, 04763, South Korea. Electronic address:

We reviewed washing of radioactive Cs-contaminated concrete and soil based on the fate of Cs in concrete and soil, including sorption materials for treatment of supernatant solution. In non-aged cement materials (the calcium silicate hydration (C-S-H) phase), it was possible to decontaminate Cs using ion exchange with monovalent cations, such as NH. The clay components in the soil and aggregates were important factors in optimization of the efficiency and mechanism for Cs decontamination with washing solution. Read More

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High-performance reversible aqueous zinc-ion battery based on iron-doped alpha-manganese dioxide coated by polypyrrole.

J Colloid Interface Sci 2021 Apr 16;598:419-429. Epub 2021 Apr 16.

School of Materials Science and Engineering, State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, PR China.

The development of zinc-ion storage cathode materials for aqueous zinc-ion batteries (AZIBs) is a necessary step for the construction of large-scale electrochemical energy conversion and storage devices. Iron-doped alpha-manganese dioxide (α-MnO) nanocomposites were achieved in this study via pre-intercalation of Fe during the formation of α-MnO crystals. A polypyrrole (PPy) granular layer was fabricated on the surface of α-MnO using acid-catalyzed polymerization of pyrroles. Read More

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Growth kinetics of RS1 on fluorene and dibenzothiophene, concomitant degradation kinetics and uptake mechanism.

3 Biotech 2021 Apr 26;11(4):195. Epub 2021 Mar 26.

IIT Bombay, Mumbai, India.

The current study illustrates the growth kinetics of an efficient PAH and heterocyclic PAH degrading bacterial strain, RS1 on fluorene (FLU) and dibenzothiophene (DBT) over the concentration 25-500 mg L and their concomitant degradation kinetics. The specific growth rate () was found to lie within the range of 0.32-0. Read More

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Research and Development of Novel Refractory of MgO Doped with ZrO Nanoparticles for Copper Slag Resistance.

Materials (Basel) 2021 Apr 28;14(9). Epub 2021 Apr 28.

Faculty of Mechanical and Electrical Engineering, Autonomous University of Nuevo Leon, San Nicolás de los Garza 66450, Mexico.

This study investigates the corrosion mechanism on 100 wt.% MgO and 95 wt.% MgO with 5 wt. Read More

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Supercritical Fluid Technology for the Development of 3D Printed Controlled Drug Release Dosage Forms.

Pharmaceutics 2021 Apr 13;13(4). Epub 2021 Apr 13.

Department of Pharmaceutical Technology, Eberhard Karls University, Auf der Morgenstelle 8, 72076 Tuebingen, Germany.

Supercritical CO loading of preformed 3D printed drug carriers with active pharmaceutical ingredients (APIs) shows great potential in the development of oral dosage forms for future personalized medicine. We designed 3D printed scaffold like drug carriers with varying pore sizes made from polylactic acid (PLA) using a fused deposition modelling (FDM) 3D printer. The 3D printed drug carriers were then loaded with Ibuprofen as a model drug, employing the controlled particle deposition (CPD) process from supercritical CO. Read More

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Electrospun Janus Beads-On-A-String Structures for Different Types of Controlled Release Profiles of Double Drugs.

Biomolecules 2021 Apr 25;11(5). Epub 2021 Apr 25.

School of Health Sciences, Caritas Institute of Higher Education, Hong Kong 999077, China.

A side-by-side electrospinning process characterized by a home-made eccentric spinneret was established to produce the Janus beads-on-a-string products. In this study, ketoprofen (KET) and methylene blue (MB) were used as model drugs, which loaded in Janus beads-on-a-string products, in which polyvinylpyrrolidone K90 (PVP K90) and ethyl cellulose (EC) were exploited as the polymer matrices. From SEM images, distinct nanofibers and microparticles in the Janus beads-on-a-string structures could be observed clearly. Read More

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Positive Influence of Liquid Sodium Silicate on the Setting Time, Polymerization, and Strength Development Mechanism of MSWI Bottom Ash Alkali-Activated Mortars.

Materials (Basel) 2021 Apr 12;14(8). Epub 2021 Apr 12.

School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 21116, No 1, Daxue Road, Xuzhou 221116, China.

Setting time and mechanical properties are key metrics needed to assess the properties of municipal solid waste incineration (MSWI) bottom ash alkali-activated samples. This study investigated the solidification law, polymerization, and strength development mechanism in response to NaOH and liquid sodium silicate addition. Scanning electron microscopy and X-ray diffraction were used to identify the formation rules of polymerization products and the mechanism of the underlying polymerization reaction under different excitation conditions. Read More

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In Vitro Drug Release, Permeability, and Structural Test of Ciprofloxacin-Loaded Nanofibers.

Pharmaceutics 2021 Apr 15;13(4). Epub 2021 Apr 15.

Interdisciplinary Excellence Centre, Faculty of Pharmacy, Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, Eötvös Street 6, H-6720 Szeged, Hungary.

Nanofibers of the poorly water-soluble antibiotic ciprofloxacin (CIP) were fabricated in the form of an amorphous solid dispersion by using poly(vinyl pyrrolidone) as a polymer matrix, by the low-cost electrospinning method. The solubility of the nanofibers as well as their in vitro diffusion were remarkably higher than those of the CIP powder or the physical mixture of the two components. The fiber size and morphology were optimized, and it was found that the addition of the CIP to the electrospinning solution decreased the nanofiber diameter, leading to an increased specific surface area. Read More

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Influence of Glycerophosphate Salt Solubility on the Gelation Mechanism of Colloidal Chitosan Systems.

Int J Mol Sci 2021 Apr 14;22(8). Epub 2021 Apr 14.

Department of Chemical Engineering, Lodz University of Technology, 90-924 Lodz, Poland.

Recently, thermosensitive chitosan systems have attracted the interest of many researchers due to their growing application potential. Nevertheless, the mechanism of the sol-gel phase transition is still being discussed, and the glycerophosphate salt role is ambiguous. The aim of the work is to analyze the possibility of the exclusive use of a non-sodium glycerophosphate salt and to determine its impact on the gelation conditions determined by rheological and turbidimetric measurements as well as the stability of the systems by measuring changes in the Zeta potential value. Read More

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Calibrating the Impressed Anodic Current Density for Accelerated Galvanostatic Testing to Simulate the Long-Term Corrosion Behavior of Buried Pipeline.

Materials (Basel) 2021 Apr 21;14(9). Epub 2021 Apr 21.

School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419, Korea.

Various studies have been conducted to better understand the long-term corrosion mechanism for steels in a soil environment. Here, electrochemical acceleration methods present the most efficient way to simulate long-term corrosion. Among the various methods, galvanostatic testing allows for accelerating the surface corrosion reactions through controlling the impressed anodic current density. Read More

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Nanocomposite Anion Exchange Membranes with a Conductive Semi-Interpenetrating Silica Network.

Membranes (Basel) 2021 Apr 4;11(4). Epub 2021 Apr 4.

MADIREL (UMR 7246) and International Laboratory, Ionomer Materials for Energy, Campus St Jérôme, Aix Marseille University, CNRS, 13013 Marseille, France.

Nanocomposite anion exchange membranes were synthesized based on poly(sulfone trimethylammonium) chloride. A hybrid semi-interpenetrating silica network containing a large amount of quaternary ammonium groups was prepared by two sol-gel routes, in situ with a single precursor, -trimethoxysilylpropyl-,,-trimethylammonium chloride (TMSP), or ex situ mixing two precursors, TMSP and 3-(2-aminoethylamino)propyldimethoxy-methylsilane (AEAPS). The properties of these hybrid composites and their degradation after immersion in 1 M KOH at 60 °C were studied. Read More

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Understanding the effects of anion interactions with Ag electrodes on electrochemical CO2 reduction in choline halide electrolytes.

ChemSusChem 2021 Apr 27. Epub 2021 Apr 27.

University of Queensland, School of Chemical Engineering, The School of Chemical Engineering, The University of Queensland, 4072, St Lucia, AUSTRALIA.

Interactions of electrolyte ions at electrocatalyst surfaces influence the selectivity of electrochemical CO2 reduction (CO2R) to chemical feedstocks like carbon monoxide. We investigated the effects of anion type in aqueous choline halide solutions (ChCl, ChBr, and ChI) on the selectivity of CO2R to CO over a silver (Ag) foil cathode. Using an H-type cell, we observed that halide specific adsorption at the Ag surface limits CO Faradaic efficiency (FECO) at potentials more positive than -1. Read More

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Formation Mechanism of Monodispersed Polysilsesquioxane Spheres in One-Step Sol-Gel Method.

Langmuir 2021 Apr 27. Epub 2021 Apr 27.

The State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.

Monodispersed polysilsesquioxane (PSQ) spheres with diameters from hundreds of nanometers to several microns have been successfully synthesized; however, the knowledge of their formation mechanism still lags behind. Herein, with methyltrimethoxysilane and 3-mercaptopropyl trimethoxysilane as model silicon sources, the formation process of PSQ spheres in the one-step sol-gel method was revealed for the first time by monitoring the time evolution of particle morphology, size, and size distribution via transmission electron microscopy and dynamic light scattering. A four-stage formation mechanism was proposed: rapid hydrolysis of organic silicon source and subsequent oligomer micelle nucleation, fast growing of nuclei particles and formation of their aggregates, followed by a further relatively fast growth of dispersed particles, and finally a slow growth to form monodispersed PSQ spheres. Read More

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Microwave-assisted Preparation of Cross-linked Gelatin-Paracetamol Matrices: Optimization Using the D-optimal Design

Turk J Pharm Sci 2021 04;18(2):167-175

International Medical University School of Pharmacy, Department of Pharmaceutical Technology, Kuala Lumpur, Malaysia

Objectives: This study was conducted to assess the effect of microwave heating on the preparation of paracetamol cross-linked gelatin matrices by using the design of experiment (DoE) approach and explore the influence of the duration of microwave irradiation, the concentrations of crosslinker, and the amount of sodium bicarbonate (salt) on paracetamol release. These parameters were also compared with those of the matrices prepared via conventional heating.

Materials And Methods: Twenty gel matrices were prepared with different durations of microwave irradiation, amounts of maize, and concentrations of sodium bicarbonate as suggested by Design Expert (DX). Read More

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Lead immobilization in soil using new hydroxyapatite-like compounds derived from oyster shell and its uptake by plant.

Chemosphere 2021 Apr 14;279:130570. Epub 2021 Apr 14.

State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, No. 130, Meilong Road, Shanghai, 200237, China; National Engineering Laboratory for Industrial Wastewater Treatment, East China University of Science and Technology, No. 130 Meilong Road, Shanghai, 200237, China. Electronic address:

Protecting the natural environment and ecological systems from the inorganic pollutants such as lead (Pb) has highlighted the urgent need to develop new and effective approaches for this substance's immobilization in soil. In this study, new, low-cost, and eco-friendly hydroxyapatite (HAp)-like compounds were prepared by reacting oyster shell (Oys) with diammonium phosphate ((NH)HPO) (DAP) and calcium hydroxide (Ca(OH)) at 25-28 °C (OyOHr) and 100 °C (OyOHh). Furthermore, OyOHr and OyOHh were assessed for their effectiveness to immobilize Pb in soil and suppress Pb uptake by Indian spinach (Basella Alba L. Read More

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Solubilizing Temperature of Crystalline Drug in Polymer Carrier: A Rheological Investigation on a Posaconazole-Copovidone System with Low Drug Load.

Eur J Pharm Biopharm 2021 Apr 22. Epub 2021 Apr 22.

Merck Research Laboratories, Merck & Co., Inc., West Point, PA, USA.

Measuring the solubility of a crystalline active pharmaceutical ingredient (API) in a polymer-rich system is challenging due to the high viscosity of the polymer which kinetically impedes reaching the solubility equilibrium. In this study, a rheological approach of determining the solubilizing temperature of a crystalline API in a polymeric carrier has been developed. To validate the method, a model physical mixture of crystalline posaconazole and copovidone with a relatively low API load (25wt%) was utilized. Read More

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Short reaction times coupled with alkalization improves the release of phosphorus from Al-waste activated sludge.

Bioresour Technol 2021 Apr 16;333:125168. Epub 2021 Apr 16.

Nanjing Jiangning Water Business Group Company Limited, Nanjing, Jiangsu 211161, People's Republic of China.

In this study, the performance and mechanism of P release from Al-waste activated sludge (WAS) via wet-chemical treatment at different reaction times were investigated. The maximum P release (46% of TP) was achieved at 20 min when the pH was maintained at 2 during acidic treatment. During alkali treatment, the maximum P concentration (363. Read More

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Exploring the fabrication and transfer mechanism of metallic nanostructures on carbon nanomembranes via focused electron beam induced processing.

Beilstein J Nanotechnol 2021 7;12:319-329. Epub 2021 Apr 7.

Physikalische Chemie II, Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.

Focused electron beam-induced processing is a versatile method for the fabrication of metallic nanostructures with arbitrary shape, in particular, on top of two-dimensional (2D) organic materials, such as self-assembled monolayers (SAMs). Two methods, namely electron beam-induced deposition (EBID) and electron beam-induced surface activation (EBISA) are studied with the precursors Fe(CO) and Co(CO)NO on SAMs of 1,1',4',1''-terphenyl-4-thiol (TPT). For Co(CO)NO only EBID leads to deposits consisting of cobalt oxide. Read More

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Cooperative Ligands in Dissolution of Gold.

Chemistry 2021 Apr 21. Epub 2021 Apr 21.

University of Helsinki, Department of Chemistry, PO Box 55 A.I. Virtasen aukio 1, Laboratory of Inorganic Chemistry, FIN-00014, Helsinki, FINLAND.

Development of new, environmentally benign dissolution methods for metallic gold is driven by needs in the circular economy. Gold is widely used in consumer electronics, but sustainable and selective dissolution methods for Au are scarce. Herein we describe a quantitative dissolution of gold in organic solution under mild conditions using hydrogen peroxide as an oxidant. Read More

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Eusociality through conflict dissolution.

Proc Biol Sci 2021 Apr 21;288(1949):20210386. Epub 2021 Apr 21.

Institute for Advanced Study in Toulouse, University of Toulouse Capitole, Toulouse, France.

Eusociality, where largely unreproductive offspring help their mothers reproduce, is a major form of social organization. An increasingly documented feature of eusociality is that mothers induce their offspring to help by means of hormones, pheromones or behavioural displays, with evidence often indicating that offspring help voluntarily. The co-occurrence of maternal influence and offspring voluntary help may be explained by what we call the converted helping hypothesis, whereby maternally manipulated helping subsequently becomes voluntary. Read More

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Mechanism of separation and removal of water from oily sludge using liquid dimethyl ether to dissolve hydrocarbons.

Chemosphere 2021 Mar 31;279:130452. Epub 2021 Mar 31.

College of Environment, Hohai University, Nanjing, 210098, PR China.

The effective disposal of oily sludge generated from the petroleum industry has received increasing concern. The primary difficulty for the reduction and resource utilization of oily sludge is dewatering. Therefore, finding an efficient and energy-saving dewatering technology is an urgent need for the treatment of oily sludge. Read More

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Repeated intratracheal instillation of zinc oxide nanoparticles induced pulmonary damage and a systemic inflammatory response in cynomolgus monkeys.

Nanotoxicology 2021 Apr 18:1-15. Epub 2021 Apr 18.

Jeonbuk Branch Institute, Korea Institute of Toxicology, Jeongeup, Republic of Korea.

Recently, some researchers have demonstrated that inhaled zinc oxide nanoparticles (ZnONPs) induce an acute systemic inflammatory response in workers. Considering nonhuman primates are preferably considered an animal model for translational research due to their proven similarity with humans in terms of genetics and physiology, we intratracheally instilled ZnONPs to cynomolgus monkey for 14 days and identified the toxic mechanism and bioaccumulation. ZnONPs were rapidly ionized or aggregated in a simulated pulmonary fluid, and they attracted neutrophils to the lungs and increased the pulmonary level of inflammatory mediators. Read More

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Laser diffraction as a powerful tool for amorphous solid dispersion screening and dissolution understanding.

Eur J Pharm Sci 2021 Apr 16;163:105853. Epub 2021 Apr 16.

R&D Analytical Development, Hovione Farmaciencia SA, Lumiar, 1649-038 Lisboa, Portugal.

Biopharmaceutics Classification System (BCS) class II and IV drugs may be formulated as supersaturating drug delivery systems (e.g., amorphous solid dispersions [ASDs]) that can generate a supersaturated drug solution during gastrointestinal (GI) transit. Read More

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