scholarly journals Particle diffusional layer thickness in a USP dissolution apparatus II: A combined function of particle size and paddle speed

2008 ◽  
Vol 97 (11) ◽  
pp. 4815-4829 ◽  
Author(s):  
Jennifer J. Sheng ◽  
Paul J. Sirois ◽  
Jennifer B. Dressman ◽  
Gordon L. Amidon
Keyword(s):  
Particle Size ◽  
Layer Thickness ◽  
Dissolution Apparatus

A SIMULATION STUDY ON THE EFFECT OF PARTICLE SIZE DISTRIBUTION ON THE PRINTED GEOMETRY IN SELECTIVE LASER MELTING

2021 ◽  
pp. 1-14
Author(s):  
Vaishak Ramesh Sagar ◽  
Samuel Lorin ◽  
Johan Göhl ◽  
Johannes Quist ◽  
Christoffer Cromvik ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Layer Thickness ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Powder Bed ◽  
Mean Particle Size ◽  
Final Layer ◽  
Effect Of Particle Size

Abstract Selective laser melting (SLM) process is a powder bed fusion additive manufacturing process that finds applications in aerospace and medical industries for its ability to produce complex geometry parts. As the raw material used is in powder form, particle size distribution (PSD) is a significant characteristic that influences the build quality in turn affecting the functionality and aesthetics aspects of the product. This paper investigates the effect of PSD on the printed geometry for 316L stainless steel powder, where three coupled in-house simulation tools based on Discrete Element Method (DEM), Computational Fluid Dynamics (CFD), and Structural Mechanics are employed. DEM is used for simulating the powder bed distribution based on the different powder PSD. The CFD is used as a virtual testbed to determine thermal parameters such as heat capacity and thermal conductivity of the powder bed viewed as a continuum. The values found as a stochastic function of the powder distribution is used to analyse the effect on the melted zone and deformation using Structural Mechanics. Results showed that mean particle size and PSD had a significant effect on the packing density, melt pool layer thickness, and the final layer thickness after deformation. Specifically, a narrow particle size distribution with smaller mean particle size and standard deviation produced solidified final layer thickness closest to nominal layer thickness. The proposed simulation approach and the results will catalyze in development of geometry assurance strategies to minimize the effect of particle size distribution on the geometric quality of the printed part.

Paper 3: Influence of the Atmosphere on the Endurance of Some Solid Lubricants Compared at Constant Layer Thickness

1968 ◽  
Vol 183 (9) ◽  
pp. 18-27 ◽  
Author(s):  
A. W. J. de Gee ◽  
A. Begelinger ◽  
G. Salomon
Keyword(s):  
Particle Size ◽  
Layer Thickness ◽  
Film Formation ◽  
Film Surface ◽  
Solid Lubricants ◽  
Dual Role ◽  
Constant Thickness ◽  
Lubricant Degradation ◽  
Layer Formation ◽  
Lubricant Films

Friction and endurance of five powdered solid lubricants were studied on a pin and ring machine. Simple methods were developed to produce layers of constant thickness (1 μm). The ease of rubbing-in varies widely with structure and with particle size. Ease of layer formation is completely unrelated to endurance: NbSe2 is rubbed in readily, but is rubbed off directly on loading. Layers of constant thickness from MoS2, WS2, and WSe2 powders behave roughly similarly, but MoS2 has a much longer life. The lubricant films are gradually destroyed by oxidation and therefore endurance increases in the series oxygen, air, and nitrogen (with 100 p.p.m. oxygen). The process of lubricant degradation is the same for the synthetic crystalline powders as found previously for MoS2: blistering of the run-in film surface on release of loading. Oxygen accelerates this process, leading finally to descaling and the onset of seizure. The endurance of MoSe2 goes through a pronounced maximum in oxygen–nitrogen mixtures. It is suggested that oxygen plays a dual role, first by enhancing film formation, and second by causing oxidative embrittlement of the lubricant.

scholarly journals Preparation and characterization of Gliclazide incorporated Cellulosic Microspheres: studies on drug release, compatibility and micromeritics

2015 ◽  
Vol 13 (2) ◽  
pp. 149-166 ◽  
Author(s):  
Navid Jubaer Ayon ◽  
Ikramul Hasan ◽  
Md Shfiqul Islam ◽  
Md Selim Reza
Keyword(s):  
Particle Size ◽  
Drug Release ◽  
Surface Morphology ◽  
Sustained Release ◽  
Release Rate ◽  
Drug Loading ◽  
Angle Of Repose ◽  
Flow Properties ◽  
Dissolution Apparatus

Polymeric microspheres of gliclazide were prepared to provide sustained release delivery of gliclazide to aid in continuous therapy with high margin of safety. Gliclazide was microencapsulated with different polymers namely HPMC K100LV, Ethocel (20 cps) and HPMC K100M by emulsion solvent evaporation technique using acetone as internal phase and liquid paraffin as external phase. Seventeen formulations were prepared using different drug loading and polymeric ratio of which nine formulations were prepared by a 32 full factorial design. Each formulation was evaluated for flow properties, particle size, surface morphology, drug entrapment efficiency, drug release and compatibility. Yield (%) for every batch of microspheres was measured. Flow properties of the microspheres were examined by determining bulk density, tapped density, Carr’s compressibility index, Hausner ratio and angle of repose. Particle size distribution was examined by sieving and particle size analyzer. Surface morphology was determined by scanning electron microscopy (SEM). In-vitro drug release was studied in a paddle type dissolution apparatus (USP Type II Dissolution Apparatus) for a period of 8 hours at 37°C using phosphate buffer ( pH 7.4). FTIR and DSC studies established compatibility of the drug with the polymers. Microspheres prepared with Ethocel (20 cps) and HPMC K100M were free flowing than those prepared only with HPMC K100LV. Entrapment efficiencies were within 75.88-99.69%. Microspheres prepared with Ethocel (20 cps) and HPMC K100M showed more sustained release when compared to microspheres prepared with HPMC K100LV only. Increase in drug loading resulted in increased drug release for the microspheres. Kinetic modeling of in vitro dissolution profiles revealed the drug release mechanism ranging from diffusion controlled to anomalous type. Ethocel and HPMC K100M in a ratio of 1:3 exhibited better sustained release properties than 1:1 and 3:1 ratios. The release rate of gliclazide from microspheres prepared with Ethocel (20 cps) and HPMC K100M was less than the release rate of gliclazide from microspheres prepared with HPMC K100LV, demonstrating Ethocel and HPMC K100M as suitable polymeric blend for preparing the controlled release formulation for gliclazide whereas, HPMC K100LV was found not suitable candidate when used alone as a polymer. DOI: http://dx.doi.org/10.3329/dujps.v13i2.21893 Dhaka Univ. J. Pharm. Sci. 13(2): 149-166, 2014 (December)

Discussion on the Decomposition Laws of Limestone during Converter Steelmaking Process by Static Decomposition Model under Constant Temperature

2011 ◽  
Vol 233-235 ◽  
pp. 2648-2653 ◽  
Author(s):  
Luo Fang Guo ◽  
Hong Li ◽  
Zi Quan Li ◽  
Yong Qing Li ◽  
Wen Chen Song ◽  
...  
Keyword(s):  
Particle Size ◽  
Layer Thickness ◽  
Constant Temperature ◽  
Decomposition Rate ◽  
Large Particle ◽  
Converter Steelmaking ◽  
Steelmaking Process ◽  
Decomposition Model ◽  
Unreacted Core ◽  
Unreacted Core Model

Variations of decomposition rate and decomposition layer thickness of six spherical limestone particles with different sizes are calculated and compared with each other by the experiments and model of static decomposition of limestone under constant temperature. The results indicate that: the decomposition process of limestone can be explained by unreacted core model (UCM) when it is heated sharply; the decomposition rate of large particle is greater than that of small one; the smaller particle size, the larger decomposition layer thickness in unit time.

scholarly journals Energy estimation of the interaction of a roller vibratory classifier’s blade with crushed rock mass for solving design problems

2020 ◽  
Vol 168 ◽  
pp. 00058
Author(s):  
Volodymyr Nadutyi ◽  
Valentyna Chеlyshkinа ◽  
Vitalii Sukhariev ◽  
Jamil Haddad
Keyword(s):  
Particle Size ◽  
Rock Mass ◽  
Layer Thickness ◽  
Pair Correlation ◽  
Initial Moisture Content ◽  
Crushed Rock ◽  
Regression Equations ◽  
Energy Estimation ◽  
New Device ◽  
Correlation And Regression Analysis

The roller vibratory classifier is equipped with an impact device for implementing vibro-shock mode, which improves the classification efficiency, especially of viscous and wet materials. The new device is a disk nozzle with blades, which are made like petals of wearresistant polymer. The immersion of a petal at a given depth in a crushed rock mass is investigated experimentally. Theoretical studies includes pair correlation and regression analysis methods. It is obtained that an increase in humidity promotes penetration and leads to a decrease in the energy necessary for impact, whereas an increase in particle size and layer thickness leads to its increase. Analysis of regression equations makes it possible to establish the percentage ratio of influencing factors. The article presents mathematical models of impact energy from variable factors for the initial moisture content of the material, including separately for small classes (-2.5 + 1) mm and further, with variation of all three parameters in the range: layer thickness – 20-40 mm, particle size 1-10 mm, humidity – up to 9 %. The obtained correlation dependencies and regression models are necessary for improving the existing and designing new blade-type roller vibratory classifiers.

scholarly journals Novel Sensing Approach for LPG Leakage Detection—Part II: Effects of Particle Size, Composition, and Coating Layer Thickness

2016 ◽  
Vol 16 (4) ◽  
pp. 1088-1094 ◽  
Author(s):  
Anindya Nag ◽  
Asif Iqbal Zia ◽  
Xie Li ◽  
Subhas Chandra Mukhopadhyay ◽  
Jurgen Kosel
Keyword(s):  
Particle Size ◽  
Layer Thickness ◽  
Coating Layer ◽  
Size Composition ◽  
Leakage Detection ◽  
Particle Size Composition ◽  
Coating Layer Thickness

Dissolution Improvement of Itraconazole by a Nanoparticulate System Containing Lecithin-Pectin Complexes

2013 ◽  
Vol 747 ◽  
pp. 162-165 ◽  
Author(s):  
Pornsak Sriamornsak ◽  
Sontaya Limmatvapirat ◽  
Kamonrak Cheewatanakornkool
Keyword(s):  
Thin Film ◽  
Particle Size ◽  
Zeta Potential ◽  
Surface Charge ◽  
Low Cost ◽  
Drug Carriers ◽  
Drug Dissolution ◽  
Lipophilic Drug ◽  
Dissolution Apparatus ◽  
Film Method

Nanoparticulate system composing of polymeric or lipid materials have been proposed as drug carriers for improving efficacy of encapsulated drugs. Different materials, e.g. phospholipids and polysaccharides, have been proposed for the production of these systems due to their biocompatibility, biodegradability, low cost and safety. In this study, we report a novel particulate system containing lecithin-pectin complexes loaded with a lipophilic drug, itraconazole. The effect of pectin concentration on particle formation and drug dissolution was also investigated. The lecithin-pectin complexes were prepared by thin film method using soya lecithin and then hydrated with different concentration of pectin solution. The surface charge (zeta potential) and particle size of complex particles were characterized. The drug dissolution was determined by using USP dissolution apparatus. The results demonstrated that the particle size of complex particles were in nanometer range. When concentration of pectin increased, the size increased slightly while the surface charge of complex particles was less negative. The drug dissolution from complex particles containing lecithin and pectin was higher than those containing only pectin.

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