Home About us Contact
|
Home About us Contact | ||
|
|
||
Deposition Efficiency (deposition + efficiency)
Selected AbstractsDeposition of 90YPO4 and 144CePO4 radioisotopes on polymer surfaces for radiation delivery devicesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2002Xin Qu Abstract Intravascular irradiation with , emitters inhibits restenosis in arteries after balloon angioplasty or stent implantation. Yttrium-90 (90Y, T1/2=64 h) and cerium-144 (144Ce, T1/2=286 d) emit beta particles (Emax=2.28,3.50 MeV) having an ideal energy range for brachytherapy delivery system. In this article, a previously reported method for depositing 32P on poly(ethylene terephtalate) (PET) surfaces is generalized and modifications that allow deposition of other ,-emitting radioisotopes, such as 90Y and 144Ce, are demonstrated. PET films were first coated with chitosan hydrogel and then adsorbed different amounts of phosphoric acid (PA) in aqueous solutions. Yttrium was deposited onto the surface as YPO4 after the films were immersed in YCl3 solutions. 1 ,Ci 90YCl3 (2×10,9 g) was used in each sample as a tracer for measuring the deposition efficiency, which is defined as the percentage of YCl3 deposited on the surface compared to the amount of YCl3 in solutions before the deposition. In order to improve the safety of brachytherapy treatments, polyurethanes were used to seal the deposited radioisotopes on the surface to minimize the leakage of the isotopes into the patients. The generality of this method presented here for a wide variety of particular radioisotopic components allows design of a broad range of versatile radioisotope sources. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 98,105, 2002; DOI 10.1002/jbm.10095 [source] Electrostatic effects on inertial particle transport in bifurcated tubesAICHE JOURNAL, Issue 6 2009Fong Yew Leong Abstract Most aerosols found naturally in the ambient environment or those dispersed from artificial devices such as dry powder inhalers, are electrically charged. It is known that a strong electrostatic charge on aerosols can result in transport behavior dramatically different from that of uncharged aerosols, even in the absence of an external electric field. In the present work, we study pneumatic transport of corona-charged particles in bifurcated tubes. This is accomplished by tracking the motion of discrete particles numerically under the influence of drag, gravitational, and electrostatic forces. The model aerosol is fly ash powder, whose size and charge distributions have been determined experimentally. The electrical mobility of the charged particle cloud is modeled through coulombic interactions between discrete point charges. For the case of polydispersed particles electrically charged across a distribution, the deposition efficiency was found to be greater than what is indicated by the mean charge and size. In particular, use of negatively charged fly ash powder of mean size of 2 ,m and mean charge of ,1.5 C/kg led to significant increase in deposition efficiency (,29%) compared with uncharged fly ash powder of the same size distribution (,8%). Analysis of particle residence times suggests significant interaction between electrical and drag forces. These findings could have implications for pneumatic powder conveying or pulmonary drug delivery applications. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] A Human Oral-throat Cast Integrated with a Twin-stage Impinger for Evaluation of Dry Powder InhalersJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2000T. SRICHANA The aim of this study was to investigate the applicability of replacing the glass throat from a twin-stage impinger (TSI) with a human oral-throat cast. Monodisperse aerosols were used to calibrate the human oral cast-TSI at 60 L min,1 and cut-off in particle size was compared with that of the TSI described in the British Pharmacopoeia which employs a glass throat. The amount of salbutamol sulphate (and lactose) delivered by the Cyclohaler depositing on various elements of the in-vitro model were determined. The calibration of the model containing a human oral-throat cast at 60 L min,1 gave a particle size cut-off of 5.2 ,m which was less than that of the TSI (6.3 ,m). The oral-throat cast trapped more drug than the glass throat model with a formulation that employed the larger carrier (63,90 ,m; P<0.05) while it trapped a lesser amount of drug with those filled with the lower size carrier (Lactochem, micronised lactose). The greater amount of lactose in the formulation that employed the larger-sized carrier (63,90 ,m) was deposited closer to the inlet of the oral-throat cast than to the inlet of the glass throat model. Replacement of the glass throat in the TSI by the human oral-throat cast, leads to a change in deposition efficiency, with the cast having a higher filter efficiency and hence more aerosol particles being captured before their entry into the TSI. This should be investigated further to determine whether such a model might provide a more realistic assessment of the in-vivo characteristics of an aerosol in comparison with the TSI currently being employed, which utilises the glass throat as the portal of entry. [source] Influence of Plasma Spray Parameters on Formation and Morphology of ZrO2,8 wt% Y2O3 DepositsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2001Ahmet Kucuk Spray prints of thermal spray coatings were created on glass slides for air-plasma-sprayed 8-wt%-yttria-partially-stabilized zirconia (YSZ) deposits. The spray parameters such as carrier gas flow rate, standoff distance, and torch power were systematically changed to investigate the influence of these parameters on the YSZ deposit characteristics. The deposit properties such as deposition efficiency (DE), substrate coverage, deposit thickness, and roughness were measured. The deposits sprayed with a 3.5,4.0 L/min carrier gas flow rate at an 80 mm standoff distance exhibited higher values of DE within the range of studied process parameters. The DE increased as much as 25% by varying the carrier gas flow rate from 2.0 to 4.0 L/min. The deposits sprayed at a higher standoff distance and low torch power gave poor deposit characteristics. The deposit characteristics were compared with the in-flight particle parameters and revealed that the deposit characteristics strongly depended on the in-flight particle temperature. Using the in-flight particle properties, the flattening ratio and the splat thickness were calculated. The average size of particles adhering to the substrate was found to drastically change with a change of process conditions, being much less than the average size of the starting powder. [source] | ||||||||||