211 research outputs found
Drop Impact onto a Metallic Porous Layer: Effect of Liquid Viscosity and Air Entrapment
Get PDFThe drop impact onto porous surfaces has important applications in many fields, such as painting, paper coating,drug delivery and cosmetic sprays. In most of these applications, the optimisation of the deposition process is carried out empirically, without a proper understanding of the physics and a theoretical modelling of the spreading and the imbibition phenomena. The purpose of this study is to analyse droplet impacts on metallic meshes to define a general modelling strategy of the impact regimen on particular 2D regular porous surfaces. The application of this structure is relevant in process like filtration but also in the medical field, considering for example reconstructive surgery. By analysing the impact of droplets of water, acetone and a mixture of glycerol and water, having a diameter and an impact velocity in a range of 1.5-3mm and 2-4m/s, respectively, on meshes with a pore size ranging between 25 and 400 µm, a regime map was built considering 6 different impact outcomes. The outcomes were characterised by a deposition of the droplet on the substrate, or a partial imbibition, or a total imbibition. By increasing the impact velocity, a splash region was defined, which is still characterised by a final deposition, a partial imbibition and a total imbibition. It is found that the most influencing parameters are closely linked to the liquid properties and the impact velocity, more specifically liquid surface tension plays a major role in defining the impact outcome. In the case of Acetone, the lower surface tension brings to an almost instantaneous total imbibition whereas the experiments conducted using water and glycerol solution, showed a major distribution of the deposition regimes with respect to the other outcomes, due to the effect of a higher viscosity. It was found that the geometrical characteristics of the mesh such as pore size and wire diameter, play an important role as well in defining the total imbibition outcome. Finally, the defined transition maps, shows that for a certain combination of physical properties and initial condition,the outcome of the droplet impact is predictable.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4973</jats:p
Drop impact onto attached metallic meshes:liquid penetration and spreading
Get PDFThe interaction between drops and porous matter has important applications in many fields such as painting, paper coating, design of textiles, filtration and therapeutic delivery, the latter can include also reconstructive surgery processes. Since the phenomenon of droplet impact onto a porous surface is particularly complex, a first step consists in analysing impacts on 2D structures, such as metallic porous layers. The present paper shows the case of drop impacts onto metallic meshes attached to a solid substrate. The pores are squared and not planar, due to the woven structure of the meshes: the dynamics of the flow is particulary complex, but it resembles more realistic cases. In analysing the impact of droplets of water, acetone and a mixture of glycerol and water on meshes with different pore sizes, three main outcomes were observed for both test cases: deposition, partial imbibition and penetration. Higher velocity impacts lead to droplet splashing followed by deposition, partial imbibition and penetration. A higher amount of liquid penetration is linked to a higher velocity impact, lower viscosity and a larger dimension of the pore size. A map of the regimes is proposed introducing two dimensionless numbers M and γ, that are functions of the Weber and Reynolds numbers and pore and wire sizes. Previous papers have not considered the role of the wire diameter. The two numbers allow a clear separation of the outcomes and a practical use of the results.</p
Nanocarriers with smartness and responsiveness programmed for use in therapy
No full text2nd International Conference on Nanotechnology & Nanoscience In date 2021-08-07 by ,پرديس بين المللي ارس دانشگاه تهران in City Tehran was held. This conference is held by Civilica Sponsoring and articles and will be indexed in CIVILICA.Shima KA Far, Irina N Savina, Laila Kudsiova, Dipak K Sarker (2021) Nanocarriers with smartness and responsiveness programmed for use in therapy. Conference Proceedings of the 2nd International Conference on Nanotechnology and Nanoscience. University of Tehran, Tehran, Iran, 7thAugust 2021; Presentation 411, p535, pp(1)The presented paper discusses the use of vesicular systems with entrained and encapsulated nanoparticles for use as environmentally-tuneable and sensitive diagnostic/therapeutic (theranostic) single or dual application entitie
Ghana's labor market (1987-92)
Get PDFUsing the household survey and other data sources, the authors analyze returns to education and other aspects of Ghana's labor market profile from 1987 to 1991. The labor force grew slower than the population did between 1980 and 1990, but the supply of labor is expected to increase as the population of youth is expected to grow faster from 1990 to 2000. And labor force participation rates for 26- to 45-year-olds have been increasing rapidly. Over time, the average labor force participation rates of women have become equal to men's; that of children younger than 15 has remained unchanged at 38 percent. More than half of Ghana's child laborers are employed in agriculture. The formal sector's share of employment is on the decline, while the private informal sector's share has increased, especially in urban areas. Over time, the informal sector (in which most workers have a primary education or less) has absorbed more labor than the formal sector (in which most workers have middle or secondary schooling). Unemployment is pervasive in urban areas, and is less visible in rural areas. Labor productivity may not have increased and is possibly declining. Between 1987 and 1992, there was reverse migration, with many people moving from urban to rural areas, mostly for family reasons. Employment-related migration has also been on the increase. As is true elsewhere, the level of education affects participation in the labor force. Literacy rates for women are lower than those for men, which is one reason men dominate the private formal sector. The rate of return to education increases with higher education and work experience. The return for each additional year of schooling rangesfrom 4 percent to 6 percent in Ghana, quite high for a Sub-Saharan African country. Private and social returns to education are greater for primary than for secondary or postsecondary education.Public Health Promotion,Health Economics&Finance,Health Monitoring&Evaluation,Labor Policies,Environmental Economics&Policies,Health Monitoring&Evaluation,Environmental Economics&Policies,Health Economics&Finance,Labor Standards,Poverty Assessment
Effect of Solid State Diffusion on Microsegregation in Steels
Get PDFTitle: Effect of Solid State Diffusion on Microsegregation in Steels, Author: Dipak B. Moharil, Location: ThodeControlled solidification of Fe-2wt% Ni binary and Fe-2 wt% Ni-Xwt%C ternary alloys was carried out in a travelling furnace. Metallographic studies were used to observe the effect of carbon on the morphology of growth. Electron probe microanalysis was carried out to obtain
quantitative results on the microsegregation of Ni in the binary and ternary alloys. The extent of homogenization of Ni, occurring both during and after solidification was quantitatively estimated.ThesisMaster of Engineering (ME
Pharmaceutical emulsions:A drug developer's toolbag
Get PDFPharmaceutical Emulsions: A Drug Developer's Toolbag covers all the key aspects of pharmaceutical emulsions, starting from the fundamental scientific basics, to the pharmaceutical forms and the chemical tests for its application. The author uses his extensive experience in both industry and academic experience to provide a concise, student friendly guide to the essential fundamentals of physical pharmacy. Divided into three clear sections, the text begins with Section A - Consideration for Product: Medicinal Formulation which includes a historical perspective, explanation of what is an emulsion, stability and instability, and manufacture. Section B - Forms, Use and Application follows, with chapters on creams and ointments, pastes and bases, colloids, transdermal, gels and implants. The final Section, Tests: Chemistry to control the quality, efficacy and fitness for purpose of the product includes chapters on physic-chemical properties, sizing and microscopy, rheology, QC and finally questions, calculations and dilemmas. Throughout the text there are numerous figures, diagrams and tables to engage the reader. This is an invaluable reference for all students of pharmaceutical sciences, pharmacy industrial pharmaceutical sciences, physical pharmacy and pharmaceutical forms as well as industry professionals.</p
Malaysian labor markets under structural adjustment
Get PDFMalaysia's sustained growth in the 1970s was boosted by windfall gains during two oil price hikes plus a commodity boom. Oil and commodity prices fell in the 1980s and Malaysia, an oil exporter, bungled into a rather severe depression in 1985-86. But it recovered quickly, to the surprise of some - and growth resumed in 1987. The events that led to the recession and quick turnaround are a Southeast Asia prototype. The author analyzes the key relationships in this cyclical behavior. He then focuses on long-term labor market issues of interest during the economy's 20-year transformation. It was found that the real exchange rate appreciated because of the inflow of foreign capital to support the government's budget deficit. And the increase in average wages in the period leading up to the recession was not corrected with the rise in the domestic exchange rate in a fully employed economy. Wages increased more than labor productivity did at a time when employment growth had slowed and the rate of unemployment had risen. The author also concluded that rising labor costs were only part of the problem of rising costs before the recession. The whole package of fiscal, monetary, and exchange rate policies - together with the labor market behavior - led to the recession.Banks&Banking Reform,Environmental Economics&Policies,Economic Theory&Research,Economic Stabilization,Markets and Market Access
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