scholarly journals Computational Modeling of Drug Dissolution in the Human Stomach

2022 ◽  
Vol 12 ◽  
Author(s):  
Jung Hee Seo ◽  
Rajat Mittal
Keyword(s):  
Drug Concentration ◽  
Gravitational Force ◽  
Human Stomach ◽  
Drug Dissolution ◽  
Imaging Data ◽  
Average Mass ◽  
Structure Interaction ◽  
Recirculating Flow ◽  
Anatomical Imaging ◽  
Transport And Mixing

A computational model of drug dissolution in the human stomach is developed to investigate the interaction between gastric flow and orally administrated drug in the form of a solid tablet. The stomach model is derived from the anatomical imaging data and the motion and dissolution of the drug in the stomach are modeled via fluid-structure interaction combined with mass transport simulations. The effects of gastric motility and the associated fluid dynamics on the dissolution characteristics are investigated. Two different pill densities are considered to study the effects of the gastric flow as well as the gravitational force on the motion of the pill. The average mass transfer coefficient and the spatial distributions of the dissolved drug concentration are analyzed in detail. The results show that the retropulsive jet and recirculating flow in the antrum generated by the antral contraction wave play an important role in the motion of the pill as well as the transport and mixing of the dissolved drug concentration. It is also found that the gastric flow can increase the dissolution mass flux, especially when there is substantial relative motion between the gastric flow and the pill.

scholarly journals Dissolution rate enhancement of gliclazide by ordered mixing

2011 ◽  
Vol 61 (3) ◽  
pp. 323-334 ◽  
Author(s):  
Vikas Saharan ◽  
Pratim Choudhury
Keyword(s):  
Particle Size ◽  
Sodium Chloride ◽  
Dissolution Rate ◽  
Drug Concentration ◽  
Water Soluble ◽  
Drug Dissolution ◽  
Cube Root ◽  
Particle Size Range ◽  
Rate Enhancement ◽  
Dissolution Rate Enhancement

Dissolution rate enhancement of gliclazide by ordered mixingThe poorly water soluble antidiabetic drug gliclazide was selected to study the effect of excipients on dissolution rate enhancement. Ordered mixtures of micronized gliclazide with lactose, mannitol, sorbitol, maltitol and sodium chloride were prepared by manual shaking of glass vials containing the drug and excipient(s). Different water soluble excipients, addition of surfactant and superdisintegrant, drug concentration and carrier particle size influenced the dissolution rate of the drug. Dissolution rate studies of the prepared ordered mixtures revealed an increase in drug dissolution with all water soluble excipients. The order of dissolution rate improvement for gliclazide was mannitol > lactose > maltitol > sorbitol > sodium chloride. Composite granules of the particle size range 355-710 μm were superior in increasing the drug dissolution rate from ordered mixtures. Reducing the carrier particle size decreased the dissolution rate of the drug as well as the increase in drug concentration. Kinetic modeling of drug release data fitted best the Hixson-Crowell model, which indicates that all the ordered mixture formulations followed the cube root law fairly well.

Anatomical & Imaging Measures of the Left Ventricular Apical Thinning

2013 ◽  
Vol 749 ◽  
pp. 144-148
Author(s):  
Ping Zhang ◽  
Yao Hui Zhu ◽  
Chee Mun Lum ◽  
Shao Yin Duan
Keyword(s):  
Coronary Artery ◽  
Left Ventricle ◽  
Volume Rendering ◽  
Left Coronary Artery ◽  
Heart Diseases ◽  
Three Dimensional ◽  
Left Ventricular ◽  
Multiplanar Reconstruction ◽  
Imaging Data ◽  
Anatomical Imaging

Doing the heart three-dimensional CT imaging (3DCT), the writers found 3DCT can clearly show the left ventricular apical thinning (LVAT). Purpose: To observe the shape of LVAT and measure related parameters in the end-systolic and end-diastolic phases. Methods: 12 cadaveric heart specimens were observed, and the thickness of LVAT was measured, as well as the thickest myocardium of left ventricle (TMLV). There are 69 cases imaging data of the end-systolic and end-diastolic phases without heart diseases from PACS in our hospital, with multiplanar reconstruction (MPR), Volume rendering (VR), the LVAT was clearly shown and measured. Measuring parameters include the thickness of LVAT, TMLV and the distance between the LVAT and the anterior descending branch of left coronary artery (DBLCA). Statistical comparisons were made. Results: In all cadaveric heart specimens of 12 cases were found the LVAT, the thickness of LVAT, TMLV was 1.74 mm ± 0.32 mm, 13.07 mm ± 1.48 mm. 3DCT clearly showed the LVAT in the 69 cases, whose thickness was 1.17 mm ± 0.43 mm in the diastole phase and 1.19 mm ± 0.48 mm in the systole phase. The thickness of TMLV was 12.02 mm ± 1.66mm, and the distance between the LVAT and DBLCA was 13.70mm ± 3.78 mm in the diastole phase. There were not significant differences in the LVAT thickness between systole and diastole phases (t = 0.366, p > 0.5), but there are significant differences in measuring the thickness of myocardium between the anatomy and 3DCT (t = 2.210, 0.01< P<0.05). Conclusion: The LVAT can be clearly shown by anatomy and 3DCT, and its thickness does not change in the end-systolic and end-diastolic phases.

A New Method for Computing the Gravitational Force in Particle Simulations

1983 ◽  
Vol 5 (2) ◽  
pp. 182-183 ◽  
Author(s):  
J. J. Monaghan
Keyword(s):  
Gravitational Force ◽  
Mass Density ◽  
Standard Procedure ◽  
Equal Mass ◽  
New Method ◽  
Average Mass ◽  
Gravitational Forces ◽  
Particle Simulations

A standard procedure for the simulation of galaxies is to replace the ∼ 1011 stars by ∼ 104 particles. These particles are assumed to have equal mass and their distribution in space produces a mass density ϱ which mimics the average mass density of the stars. From the mass density of the particles the gravitational forces between the particles can be computed. In the literature two methods have been used to compute these forces.

scholarly journals Analytical and Computational Methods for the Estimation of Drug-Polymer Solubility and Miscibility in Solid Dispersions Development

Pharmaceutics ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 372 ◽  
Author(s):  
Djordje Medarević ◽  
Jelena Djuriš ◽  
Panagiotis Barmpalexis ◽  
Kyriakos Kachrimanis ◽  
Svetlana Ibrić
Keyword(s):  
Shelf Life ◽  
Drug Concentration ◽  
Single Phase ◽  
Drug Loading ◽  
Solid Dispersions ◽  
Physical Stability ◽  
Solubility Limit ◽  
Drug Dissolution ◽  
Phase System ◽  
Polymer Solubility

The development of stable solid dispersion formulations that maintain desired improvement of drug dissolution rate during the entire shelf life requires the analysis of drug-polymer solubility and miscibility. Only if the drug concentration is below the solubility limit in the polymer, the physical stability of solid dispersions is guaranteed without risk for drug (re)crystallization. If the drug concentration is above the solubility, but below the miscibility limit, the system is stabilized through intimate drug-polymer mixing, with additional kinetic stabilization if stored sufficiently below the mixture glass transition temperature. Therefore, it is of particular importance to assess the drug-polymer solubility and miscibility, to select suitable formulation (a type of polymer and drug loading), manufacturing process, and storage conditions, with the aim to ensure physical stability during the product shelf life. Drug-polymer solubility and miscibility can be assessed using analytical methods, which can detect whether the system is single-phase or not. Thermodynamic modeling enables a mechanistic understanding of drug-polymer solubility and miscibility and identification of formulation compositions with the expected formation of the stable single-phase system. Advance molecular modeling and simulation techniques enable getting insight into interactions between the drug and polymer at the molecular level, which determine whether the single-phase system formation will occur or not.

scholarly journals Properties of galaxy dark matter halos from weak lensing

2004 ◽  
Vol 220 ◽  
pp. 439-445 ◽  
Author(s):  
Henk Hoekstra ◽  
Howard K.C. Yee ◽  
Michael D. Gladders
Keyword(s):  
Dark Matter ◽  
Numerical Simulations ◽  
Excellent Agreement ◽  
Gravitational Lensing ◽  
Strong Support ◽  
Alternative Theories Of Gravity ◽  
Dark Matter Halos ◽  
Imaging Data ◽  
Average Mass ◽  
Theories Of Gravity

We present the results of a study of the average mass profile around galaxies using weak gravitational lensing. We use 45.5 deg2 of RC band imaging data from the Red-Sequence Cluster Survey (RCS) and define a sample of ~ 1.2 × 105 lenses with 19.5 < RC < 21, and a sample of ~ 1.5 × 106 background galaxies with 21.5 < R < 24.We constrain the power law scaling relations between the B-band luminosity and the mass and size of the halo, and find that the results are in excellent agreement with observed luminosity–line-width relations. Under the assumption that the luminosity does not evolve with redshift, the best fit NFW model yields a mass M200 = (8.8±0.7) × 1011h–1M⊙ and a scale radius rs = I6.7+3.7–3.0h–1 kpc for a galaxy with a fiducial luminosity of Lb = 1010h–2LB⊙. the latter result is in excellent agreement with predictions from numerical simulations for a halo of this mass. We also observe a signficant anisotropy of the lensing signal around the lenses, implying that the halos are flattened and aligned with the light distribution. We find an average (projected) halo ellipticity of 〈ehalo〉 = 0.20+0.04–0.05, in fair agreement with results from numerical simulations of CDM. Alternative theories of gravity (without dark matter) predict an isotropic lensing signal, which is excluded with 99.5% confidence. Hence, our results provide strong support for the existence of dark matter.

Abstract 19734: Advantages of the Cardiac Isochrone Positioning System for Localization of PVCs to the Endocardium, Epicardium, and Mid-myocardium from a 12 lead ECG

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jeffrey P Gordon ◽  
Michael Laks ◽  
Noel G Boyle ◽  
Peter M van Dam
Keyword(s):  
Clinical Benefit ◽  
New Technology ◽  
Imaging Method ◽  
Positioning System ◽  
Imaging Data ◽  
Non Invasive ◽  
Epicardial Surface ◽  
Myocardial Area ◽  
Anatomical Imaging ◽  
Correct Location

Introduction: PVC localization from a 12 lead ECG is an imperfect deduction prone to inaccuracy. The cardiac isochrone positioning system (CIPS) is a non-invasive cardiac imaging method to localize the PVC origin quantitatively to the ventricles using a 12 lead ECG coupled with anatomical imaging data from MRI/CT. The purpose of this study is to: 1) Demonstrate and clarify the limitations of using only the 12 lead ECG to localize a PVC, and 2) Show the advantages of CIPS to localize a PVC, including to the mid-myocardium. Methods: 9 subjects had successful PVC ablation in the endo- , epi, or mid-myocardium. To demonstrate the limitations of localizing PVCs using only a 12 lead ECG, 8 blinded physicians were asked both to localize the PVC origin to a specific myocardial area using polar map representations of the LV and RV and to specify the PVC as endo- or epicardial in origin. CIPS was used to localize the same PVCs using the MRI derived models and the same 12 lead ECG. Results: All 8 blinded reviewers located the PVCs to the correct location with an accuracy of 27%. A qualification of the PVC to an endo- or epicardial surface could not be reliably determined. In contrast, CIPS located the PVCs with an accuracy of 86%. CIPS also successfully localized all 9 PVCs to endo-, epi-, or mid-myocardium. Conclusions: Our results confirm the limited capability of using only a 12 lead ECG to localize a PVC origin. Currently, there are no criteria to differentiate the location of the PVC specifically to the mid-myocardium. Coupling the 12 lead ECG and anatomical data, CIPS is able to reliably determine PVC origin. As demonstrated here, it also has the ability to successfully localize PVCs to an epi-, endo-, or mid-myocardial site. CIPS is a promising new technology that could be used to quickly and accurately ascertain an exact PVC location, translating into a direct clinical benefit for patients undergoing ablation.

Imaging of platinum-shadowed macromolecular complexes in dark field

1984 ◽  
Vol 42 ◽  
pp. 146-147
Author(s):  
D.W. Andrews ◽  
F.P. Ottensmeyer
Keyword(s):  
Thin Film ◽  
Three Dimensional ◽  
Average Diameter ◽  
Dark Field ◽  
Bright Field ◽  
Field Mode ◽  
Macromolecular Complexes ◽  
Average Mass ◽  
Topological Features ◽  
Projection Images

Shadowing with heavy metals has been used for many years to enhance the topological features of biological macromolecular complexes. The three dimensional features present in directionaly shadowed specimens often simplifies interpretation of projection images provided by other techniques. One difficulty with the method is the relatively large amount of metal used to achieve sufficient contrast in bright field images. Thick shadow films are undesirable because they decrease resolution due to an increased tendency for microcrystalline aggregates to form, because decoration artefacts become more severe and increased cap thickness makes estimation of dimensions more uncertain.The large increase in contrast provided by the dark field mode of imaging allows the use of shadow replicas with a much lower average mass thickness. To form the images in Fig. 1, latex spheres of 0.087 μ average diameter were unidirectionally shadowed with platinum carbon (Pt-C) and a thin film of carbon was indirectly evaporated on the specimen as a support.

Correlation of Pore Structure and Permeability by SEM-Image Analysis

1990 ◽  
Vol 48 (1) ◽  
pp. 428-429
Author(s):  
C. A. Callender ◽  
Wm. C. Dawson ◽  
J. J. Funk
Keyword(s):  
Image Analysis ◽  
Pore Structure ◽  
Imaging System ◽  
Pore Space ◽  
Simulation Models ◽  
Image Analyzer ◽  
Imaging Data ◽  
Sem Images ◽  
Thin Sections ◽  
Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

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