Dissolution Model Research Articles

Particle Size Dependent Dissolution of Uranium Aerosols in Simulated Gastrointestinal Fluids.

Uranium aerosol exposure can be a health risk factor for workers in the nuclear fuel industry. Good knowledge about aerosol dissolution and absorption characteristics in the gastrointestinal tract is imperative for solid dose assessments and risk management. In this study, an in vitro dissolution model of the GI tract was used to experimentally study solubility of size-fractionated aerosols. The aerosols were collected from four major workshops in a nuclear fuel fabrication plant where uranium compounds such as uranium hexafluoride (UF 6 ), uranium dioxide (UO 2 ), ammonium uranyl carbonate, AUC [UO 2 CO 3 ·2(NH 4 ) 2 CO 3 ] and triuranium octoxide (U 3 O 8 ) are present. The alimentary tract transfer factor, f A , was estimated for the aerosols sampled in the study. The transfer factor was derived from the dissolution in the small intestine in combination with data on absorption of soluble uranium. Results from the conversion workshop indicated a f A in line with what is recommended (0.004) by the ICRP for inhalation exposure to Type M materials. Obtained transfer factors, f A , for the powder preparation and pelletizing workshops where UO 2 and U 3 O 8 are handled are lower for inhalation and much lower for ingestion than those recommended by the ICRP for Type M/S materials f A = 0.00029 and 0.00016 vs. 0.0006 and 0.002, respectively. The results for ingestion and inhalation f A indicate that ICRP's conservative recommendation of f A for inhalation exposure is applicable to both ingestion and inhalation of insoluble material in this study. The dissolution- and subsequent absorption-dependence on particle size showed correlation only for one of the workshops (pelletizing). The absence of correlation at the other workshops may be an effect of multiple chemical compounds with different size distribution and/or the reported presence of agglomerated particles at higher cut points having more impact on the dissolution than particle size. The impact on dose coefficients [committed effective dose (CED) per Bq] of using experimental f A vs. using default f A recommended by the ICRP for the uranium compounds of interest for inhalation exposure was not significant for any of the workshops. However, a significant impact on CED for ingestion exposure was observed for all workshops when comparing with CED estimated for insoluble material using ICRP default f A . This indicates that the use of experimentally derived site-specific f A can improve dose assessments. It is essential to acquire site-specific estimates of the dissolution and absorption of uranium aerosols as this provides more realistic and accurate dose- and risk-estimates of worker exposure. In this study, the results indicate that ICRP's recommendations for ingestion of insoluble material might overestimate absorption and that the lower f A found for inhalation could be more realistic for both inhalation and ingestion of insoluble material.

A Pharmaceutical Study on Quality Surveillance of Six Empagliflozin (10 mg) Tablet Generics in Pakistan

Sodium glucose co-transporters are a novel and potent class of anti-diabetic drugs. One of the members of this newest class of drugs is empagliflozin. It is considered as a favorable option for controlling type II diabetes mellitus. The objective of the current study is based on the quality surveillance of different empagliflozin brands in Pakistan. Six different empagliflozin counterparts (Emp-A to Emp-F) were collected and assessed for various pharmacopeial and non-pharmacopeial tests. The findings indicated good-quality features. In vitro kinetics was also evaluated by applying various dissolution models using DD-Solver software. All the six selected brands of empagliflozin generics satisfied the compendial requirement. Moreover, the percentage content obtained was within specifications (95%-105%). The applied method was validated. The released kinetic model was found to be the Korsmeyer-Peppas as the best fit at pH 6.8. The statistical evaluation (ANOVA) of the dissolution test exhibited no significant difference in the release pattern of empagliflozin substitutes (p > 1.00, 95% C.I.). This in vitro comparative approach will highlight the significant prospect and its interchangeability. Among all, Emp-A was found superior on the basis of pharmaceutical properties, while this study concluded that all empagliflozin brands available in the commercial market exhibited similar release profiles and is safe to use. Keywords: marketed brands, quality surveillance, empagliflozin. https://doi.org/10.55463/issn.1674-2974.50.3.12

Tuning the chemical composition of binary alloy nanoparticles to prevent their dissolution.

The dissolution of nanoparticles under corrosive environments represents one of the main issues in electrochemical processes. Here, a model for alloying and protecting nanoparticles from corrosion with an anti-corrosive element (e.g. Au) is proposed based on the hypothesis that under-coordinated atoms are the first atoms to dissolve. The model considers the dissolution of atoms with coordination number ≤6 on A-B nanoparticles with different sizes, shapes, chemical compositions, and exposed crystallographic orientations. The results revealed that the nanoparticle's size and chemical composition play a key role in the dissolution, suggesting that a certain composition of an element with corrosive resistance could be used to protect nanoparticles. DFT simulations were performed to support our model on the dissolution of four types of atoms commonly found on the surface of Au0.20Pd0.80 binary alloys - terrace, edge, kink, and ad atoms. The simulations suggest that the less coordinated ad and kink Pd atoms on Au0.20Pd0.80 alloys are dissolved in a potential window between 0.26-0.56 V, while the rest of the Pd and Au atoms are protected. Furthermore, to show that a corrosion-resistant element can indeed protect nanoparticles, we experimentally investigated the electrochemical dissolution of immobilized Pd, Au0.20Pd0.80, and Au0.40Pd0.60 nanoparticles in a harsh environment. In line with the dissolution model, the experimental results show that an Au molar fraction of the nanoparticle of 0.20, i.e., Au0.20Pd0.80 binary alloy, is a good compromise between maximizing the active surface area (Pd atoms) and corrosion protection by the inactive Au.

Validation of RP-HPLC method for quantification of ketoconazole in two-stage model of biorelevant dissolution: application to supersaturation study

Validation of RP-HPLC method for quantification of ketoconazole in two-stage model of biorelevant dissolution: application to supersaturation study

Report on the Virtual Workshop: A Quest for Biowaiver, Including Next Generation Dissolution Characterization and Modeling

Report on the Virtual Workshop: A Quest for Biowaiver, Including Next Generation Dissolution Characterization and Modeling

Developing and verifying a quantitative dissolution model for metal-bearing nanoparticles in aqueous media

Dissolution of nanoparticles (NPs) determines the fate and subsequently the actual exposure of biota to the NPs (created with https://BioRender.com).

Inkjet drug printing onto contact lenses: Deposition optimisation and non-destructive dose verification

Inkjet printing has the potential to advance the treatment of eye diseases by printing drugs on demand onto contact lenses for localised delivery and personalised dosing, while near-infrared (NIR) spectroscopy can further be used as a quality control method for quantifying the drug but has yet to be demonstrated with contact lenses. In this study, a glaucoma therapy drug, timolol maleate, was successfully printed onto contact lenses using a modified commercial inkjet printer. The drug-loaded ink prepared for the printer was designed to match the properties of commercial ink, whilst having maximal drug loading and avoiding ocular inflammation. This setup demonstrated personalised drug dosing by printing multiple passes. Light transmittance was found to be unaffected by drug loading on the contact lens. A novel dissolution model was built, and in vitro dissolution studies showed drug release over at least 3 h, significantly longer than eye drops. NIR was used as an external validation method to accurately quantify the drug dose. Overall, the combination of inkjet printing and NIR represent a novel method for point-of-care personalisation and quantification of drug-loaded contact lenses.

Mixed-Control Kinetic Model of Magnesia-Based Flux Dissolution in BOF Steelmaking Slags: Part 1 - Model Formulation and Validation With Literature Data

Mixed-Control Kinetic Model of Magnesia-Based Flux Dissolution in BOF Steelmaking Slags: Part 1 - Model Formulation and Validation With Literature Data

Molecular dissolution behaviors on porous membrane surface using hierarchical metal–organic framework lamellar membrane

AbstractLamellar membranes, especially assembled by microporous framework nanosheets, have excited interest for fast molecular permeation. However, the underlying molecular dissolution behaviors on membrane surface, especially at pore entrances, remain unclear. Here, hierarchical metal–organic framework (MOF) lamellar membranes with 7 nm‐thick surface layer and 553 nm‐thick support layer are prepared. Hydrophilic (–NH2) or hydrophobic (–CH3) groups are decorated at pore entrances on surface layer to manipulate wettability, while –CH3 groups on support layer provide comparable, low‐resistance paths. We demonstrate that molecular dissolution behaviors are determined by molecule–molecule and molecule–pore interactions, derived from intrinsic parameters of molecule and membrane. Importantly, two dissolution model equations are established: for hydrophobic membrane surface, dissolution activation energy (ES) obeys ES = Kmln[(γL‐γC)μd2], while turns to ES=Kaln[(γL‐γC)δeμd2] for hydrophilic one. Particularly, hydrophilic pore entrances exert strong interaction with polar molecules, thus compensating the energy consumed by molecule rearrangement, giving fast permeation (>270 L m−2 h−1 bar−1).

Semi-mechanistic reduced order model of pharmaceutical tablet dissolution for enabling Industry 4.0 manufacturing systems

We propose a generalization of the Weibull dissolution model, referred to as generalized Weibull dissolution model, that seamlessly captures all three fractional dissolution rates experimentally observed in pharmaceutical solid tablets, namely decreasing, increasing, and non-monotonic rates. This is in contrast to traditional reduced order models, which capture at most two fractional dissolution rates and, thus, are not suitable for a wide range of product formulations hindering, for example, the adoption of knowledge management in the context of Industry 4.0. We extend the generalized Weibull dissolution model further to capture the relationship between critical process parameters (CPPs), critical materials attributes (CMAs), and dissolution profile to, in turn, facilitate real-time release testing (RTRT) and quality-by-control (QbC) strategies. Specifically, we endow the model with multivariate rational polynomials that interpolate the mechanistic limiting behavior of tablet dissolution as CPPs and CMAs approach certain values of physical significance (such as the upper and lower bounds of tablet porosity or lubrication conditions), thus the semi-mechanistic nature of the reduced order model. Restricting attention to direct compaction and using various case studies from the literature, we demonstrate the versatility and the capability of the semi-mechanistic ROM to estimate changes in dissolution due to process disturbances in tablet weight, porosity, lubrication conditions (i.e., the total amount of shear strain imparted during blending), and moisture content in the powder blend. In all of the cases considered in this work, the estimations of the model are in remarkable agreement with experimental data.

Thermodynamic mechanism and its geological significance in the transformation of albite under inorganic acid environments based on the total dissolution model

Feldspar of lithosphere undergoes transformation in an acidic fluid environment. This process significantly influences the transformation of sandstone reservoirs in sedimentary basins. Currently, there is debate on the transformation mechanism, which has led to debates in predictions of favorable reservoirs in deep sedimentary basins, in terms of their origin, type, and distribution. In this study, the transformation process of feldspar is determined based on the total dissolution model, and thermodynamics is used in the calculation process. Firstly, the precipitation order of the minerals and the reaction path during the transformation process are determined. Secondly, the obtained results are compared with the results of weathered feldspar samples, laboratory-based physical simulation samples, and sandstone samples from a sedimentary basin. Finally, the changes of sandstone reservoirs which is caused by feldspar transformation processes are discussed. Based on those results, it can be deduced that the release of inter-granular particles (Na/K/Ca) in feldspar does not conform to the total dissolution model, whereas the release of lattice particles (Si and Al) conforms to the model. The total dissolution model can deduce the genetic mechanism and occurrence of authigenic kaolinite in sandstone reservoirs. When the temperature is below 120 °C, authigenic kaolinites are directly precipitated from the pore fluids or via the reaction of Al(OH)3(s) with H4SiO4(aq). The kaolinite aggregates are worm-like, with a pure chemical composition. When the temperature is above 120 °C, the feldspar particles react with Al(OH)3(s) and transformed to kaolinites. The kaolinite aggregates are particle-like, containing heteroatoms. The differences in the genetic mechanism of kaolinite lead to evident differences for type and distribution of secondary pores formed during feldspar transformation.

Finite element modeling of hydrogen migration and hydride precipitation in Zr alloys

The Finite Element software, ABAQUS® together with subroutine codes written in FORTRAN is used to fully couple the mass diffusion – displacement analysis of hydrogen redistribution and hydride precipitation in a stress gradient. Since the redistribution of hydrogen in solid solution is driven by gradients in H concentration, stress, and temperature, two different precipitation models were investigated in specimens subjected to such gradients, and the results validated against available experimental data and analytical solutions where applicable. Simulation results obtained with the new Hydride Nucleation Growth and Dissolution (HNGD) model that considers growth in the hysteresis region show closer agreement with experimental observations, signifying that the previous hydride precipitation model may be underestimating the amount of hydride precipitation.

Shape from Release

Objects with different shapes can dissolve in significantly different ways inside a solution. Predicting different shapes' dissolution dynamics is an important problem especially in pharmaceutics. More important and challenging, however, is controlling the dissolution via shape, i.e. , designing shapes that lead to a desired release behavior of materials in a solvent over a specific time. Here, we tackle this challenge by introducing a computational inverse design pipeline. We begin by introducing a simple, physically-inspired differentiable forward model of dissolution. We then formulate our inverse design as a PDE-constrained topology optimization that has access to analytical derivatives obtained via sensitivity analysis. Furthermore, we incorporate fabricability terms in the optimization objective that enable physically realizing our designs. We thoroughly analyze our approach on a diverse set of examples via both simulation and fabrication.

Study on ion dynamics of hafnium oxide RRAM by electrode thermal effect

Resistive random access memory (RRAM) has become one of the representatives of the next generation of nonvolatile memory because of its excellent performance, and the data reading function is caused by the growth and fracture of the conductive filament (CF) in the switch layer. Therefore, the study of the thermal properties of materials on the conductive mechanism is a step that cannot be ignored. In this paper, a numerical model of filament dissolution caused by the coupling effect of Joule heat and electric field in resistance elements is established. The influence of the thermal field on the electric field and ion mobility during device setup and reset is explained by solving partial differential equations. On this basis, the importance of electrode parameters for resistive switching behavior is emphasized. The results show that the best performance can be obtained at 298 K when TiN is selected as the top electrode material of the equipment. This work has deepened the understanding of RRAM resistance switch characteristics and has guiding significance for selecting memristor materials and promoting its industrialization process.

Measurement of diffusivity in supercritical carbon dioxide via particle dissolution method

A novel method of determining diffusivity in supercritical carbon dioxide is proposed based on the principle of particle dissolution. The dissolution rate of disperse blue 14 (DB14) was measured by in situ UV–vis spectroscopy and compared with a pseudo-steady-state diffusion-driven dissolution model. By minimizing the error between the experimental data and model equation via nonlinear regression, the diffusivities of DB14 at 21.9–25.7 MPa and 320–393 K were determined. The diffusivities were then compared with reference data measured using the chromatographic impulse response method. Positive deviations of 2.88%, 3.11%, and 1.41% were confirmed, suggesting the possibility and potential of the method. Further research is needed to determine and optimize the accuracy of the measurements and generalize the method to other systems.

Anion-catalyzed active dissolution model for the electrochemical adsorption of bisulfate, sulfate, and oxygen on gold in H2SO4 solution

The mechanism of the electrochemical adsorption of bisulfate, sulfate, and oxygen on polycrystalline gold in H2SO4 (0.5 M) was modeled using a mechanistic analysis of potentiodynamic polarization and electrochemical impedance spectroscopy data acquired at multiple dc potentials in the electric double-layer and pre-oxide formation region. Electrochemical quartz-crystal microgravimetry and optical ellipsometry provided evidence for the potential-dependent adsorption of solution species on the gold surface. Also, despite the high surface coverages of oxygen on the electrode surfaces, dissolution was observed over the entire the potential region studied. The anion-catalyzed active dissolution model accounts well for the experimentally observed current density and fractional surface coverages.

Dissolution characteristics of solutes with different shapes using the moving particle semi-implicit method

Dissolution characteristics of solutes with different shapes are studied. To simulate the process of dissolution, a diffusion and dissolution model based on the moving particle semi-implicit (MPS) method is proposed. First, the diffusion equation is introduced to the MPS method. Compared with the analytical solution, concentration diffusion can be accurately simulated with the model. Then, a coupling relationship between concentration, density, and viscosity is established. The relationship deals with the changes in physical parameters of the fluids caused by the diffusion, affecting the fluid flow. As the density change cannot be ignored in the mass conservation equation, the equation is re-deduced in this paper. In addition, the dissolution model is introduced to the MPS method. The dissolution model is verified by the dissolution simulation of sessile droplets in water. Finally, the dissolution of solutes with different shapes in water is simulated using the proposed method. Five cases with different solute shapes are set to simulate five different drugs. Five cases with different solute shapes are set to simulate five different drugs. The solid solute shapes used are rectangle, capsule, heart-shaped, and circle, and the liquid solute is a rectangle shape. The dissolution of the solute is comprehensively affected by the contact between the solute and water, the concentration difference, and the intensity of convection. The small concentration difference and the low convective velocity cause the existence of insoluble points in the heart-shaped case, which decreases the dissolution rate. Dimensional analysis is carried out to address the relative importance of diffusion to convection. In the dissolution of solutes with different shapes, the effect of convective cannot be ignored when the non-dimensional number is lower than 2.5 × 10−5.

Quasi-steady-state modelling and characterization of diffusion-controlled dissolution from monodisperse prolate and oblate spheroidal particles

A quasi-steady-state model of the dissolution of a single prolate or oblate spheroidal particle has been developed based on the exact solution of the steady-state diffusion equation for mass transfer in an unconfined media. With appropriate treatment of bulk concentration, the model can predict the detailed dissolution process of a single particle in a container of finite size. The dimensionless governing equations suggest that the dissolution process is determined by three dimensionless control parameters, initial solid particle concentration, particle aspect ratio and the product of specific volume of solid particles and saturation concentration of the dissolved substance. Using this model, the dissolution processes of felodipine particles are analysed in a broad range of space of the three control parameters and some characteristics are identified. The effects of material properties indicated by the product of specific volume and saturation concentration are also analysed. The model and the analysis are applicable to the system of monodisperse spheroidal particles of the same shape.

Synchronous evaluation of continuous dynamic dissolution and absorption of Compound Danshen Dropping Pills based on cellular bioelectrical effect

The real-time cell-based assay(RTCA) was used to establish the bioelectrical sensing model of Compound Danshen Dripping Pills with rat cardiomyocytes(H9 c2). The time/dose-dependent cell response profiles(TCRPs) of in vitro dissolution and absorption of the pills were determined to establish the continuous dynamic dissolution and absorption kinetic models. Thereby, the cell index(CI)-based dissolution and absorption kinetic curves and kinetic models of Compound Danshen Dripping Pills were obtained. The optimal dissolution kinetic model was Weibull model. The similarity factors f_2 of dissolution curves were greater than 50 and the correlation coefficients of absorption curves were larger than 0.95. With the experiment about the efficacy on mice, percentages of the bleeding time of mice administrated with Compound Danshen Dripping Pills were calculated, and there was a correlation among dissolution, absorption, and efficacy curves(r > 0.9). RTCA is applicable to the study of the dissolution and absorption kinetics of solid compound Chinese medicine preparations. Thus, it is an innovative and feasible method to evaluate the quality and batch consistency of compound Chinese medicine preparations.

Simultaneous Evaluation of Dissolution and Absorption Study of Compound Danshen Tablets and Capsules Based on Cellular Electrical Sensing Model.

This study explores the dissolution mechanism and absorption process of compound Danshen tablets (CDTs) and compound Danshen capsules (CDCs) in vitro. Taking the cell index as the evaluation index of dissolution and absorption of multi-component solid preparations of CDTs and CDCs, it breaks through the idea of traditional research. We used real-time cell-based assay (RTCA) to provide a new idea and method for the consistency evaluation of traditional Chinese medicine (TCM) compound preparations. The drug dissolution and absorption simulation system (DDASS) was established to obtain the dissolution and absorption samples of compound Danshen solid preparations at different time points. The cell index (CI) of the sample to H9C2 cells was detected by RTCA technology, and the dissolution and absorption percentage were calculated based on this index to obtain the dissolution and absorption kinetics model. Meanwhile, one batch of tablets and one batch of capsules (batch numbers ZKC1816 and 202101001) were selected to conduct the overall animal pharmacodynamic experiment to verify the feasibility of drug effect evaluation with cell index as an indicator. The best fitting model of dissolution curves of each batch of CDTs and CDCs is the Weibull model. There was a good correlation (r > 0.86) between the dissolution-absorption-pharmacodynamic curve. Based on RTCA technology, we have established the comprehensive evaluation method for cell biology of compound Danshen solid preparations in line with the overall concept of TCM and a synchronous evaluation system of dissolution and absorption in vitro of new TCM compound solid preparations.