1,726,880 research outputs found
Validation of differential FFF
No full textIn this talk the general concepts of validation of an analytical method are introduced, and applied to differential FFF method (1).
Chemometrics will give us the basis for defining method parameters, such as the decision, detection and quantification limits as a function of both the signal error and the blank value. FFF theory and conventional theory of signal detection will allow us to specify the different error contributions as a function of the operative parameters. Therefore by this approach the "absolute character" of SdFFF as method for mass determination is further
enlarged to include the adsolute character of the analytical method. A separate experimental check of the independent sources of errors and of the total error will represent the validation of the method.
Examples (2) are reported. The role and relevance of the FFF method validation is thus enphasized.
1. L. Bregola, C.Contado, M.Martin, L. Pasti, F. Dondi. Precision in
Differential Field-Flow Fractionation: a chemiometric study, J. Sep.
Sci., 30, 2760-2779, 2007.
2. C.Contado, L. Bregola, F. Dondi. Sedimentation field flow
fractionation of immunoglobulin A coated polystyrene beads. Influence of carrier composition on complex characterization. J. Chromatogr. A, 1169(1-2), 158-174
Dosimetric comparison between 10MV-FFF and 6MV-FFF for lung SBRT
Full text link32nd International Physics Congress of Turkish-Physical-Society (TPS) -- SEP 06-09, 2016 -- Bodrum, TURKEYPlans were prepared by using same non-coplanar fields and physical parameters in 6MV-FIT and 10MV-FFF energies for fourteen lung Stereotactic Body Radio Therapy (SBRT) patients. In two plans which have different energies, critic organ doses, PTV doses, quality of plans (Gradient Index (GI), Homogeneity Index (HI), Conformity Index (CI)) and Monitor Unit (MU) values were compared. Quality controls were performed with 2D-Array Iba MatriXX Evolution (R) dosimetry system for each plans. As a results, plan with 6MV-FFF energy give better results in terms of CI and GI values. In this way, when more conformal dose distributions were provided, there was a rapid dose decrease at out of target volume. Lower MU values were obtained in plans which was prepared with 10MV-FFF energy. In plan with IOMV-FFF energy lower MU values are obtained. Lower values in heart and spinal cord doses are founded and better results are obtained in Body and Ipsa-Lung V5, V10, V20 values with 6MV-FFF energies. When differences were very small in volume which were taken low dose (V5), these differences increased in volume which were taken high dose (V20). High dose rates can be reached by both two unfiltered energies and can be used in lung SBRT.Turkish Phys So
Mechanical Properties of Thermoplastic Polymers in Fused Filament Fabrication (FFF)
No full textFused filament fabrication (FFF) is a method used to fabricate initial prototypes out of polymeric materials with printed parts often being used as load carrying elements. The mechanical properties of various polymer materials produced under certain printing conditions exhibit superior strength and ductility and may serve as an inexpensive replacement for metal or wooden parts. To gain knowledge of 3-D printed part strength and compare the quality of filament material from several manufacturers, this study characterizes the mechanical properties of parts printed from various commercial FFF feedstocks. Uniaxial tensile testing is performed to determine the ultimate tensile strength, Youngs modulus and fracture strain, of polymer and composite materials
Field-Flow Fractionation (FFF)
No full textInternational audienceField-Flow Fractionation techniques (FFF) are size-based separation methods first described in 1966 by Giddings. They belong to the family of liquid chromatographic techniques, but they are operated without any stationary phase.Yet, they have the unique ability to separate an extremely broad range of molecules, macromolecules and particles, and in particular very large particles, with a high resolution. FFF are versatile: by varying the experimental conditions, the range, speed, and power of the separation could be optimized. FFF techniques can succeed when Size-Exclusion Chromatography (SEC) methods fails, and they have a broad range of applications. In this chapter the theory of FFF is approached together with calibration and determination of some structural parameters such as size and molar mass, the instrumentation and detection of various classic FFF types is described and we show the added value of FFF techniques for the characterization of various biopolymers including polysaccharides, proteins and natural rubber
FFF — Fit für Früherkennung und Frühintervention bei problematischem Alkoholkonsum von älteren Menschen: Schlussbericht
Full text linkDie Studie «FFF» zeigt, dass Früherkennung und Frühintervention zu problematischem Alkohol- und Medikamentenkonsum älterer Menschen in den Bereichen Spitex, Alters- und Pflegeheime sowie in Qualitätszirkeln von Haus- und HeimärztInnen noch wenig bekannt und verankert sind. Die befragten ExpertInnen und Pflegedienstleitenden anerkennen Alkohol und Medikamente im Alter als zunehmende Problematik. Hauptsächliche Barrieren für die Umsetzung bestehender, bewährter Instrumente und Konzepte liegen in einer eher geringen Sensibilisierung für Früherkennung und Frühintervention, in ethischen Spannungsfeldern und in eingeschränkten Ressourcen. Drei Massnahmenpakete wurden zur Förderung von Früherkennung und Frühintervention definiert: niederschwellige Schulungsmodule in ärztlichen Qualitätszirkeln, für Spitex-Mitarbeitende und Haushelferinnen, ein integriertes Konzept für Früherkennung und Frühintervention in Alters- und Pflegeheimen sowie ein Fortbildungsmodul für Pflegende und Leitungen in bestehenden Ausbildungsgängen von Bildungsinstitutionen. Ein Implementierungsprozedere wurde etabliert
Greening Zambia’s charcoal business for improved livelihoods and forest management through strong producer groups
No full textFinding ways to effectively monitor, manage and support sustainable production and trade in wood fuel, especially charcoal, is critical for countries across much of Africa today. In Zambia, the government, with the support of the Forest and Farm Facility (FFF), is exploring ways to help recognize and organize the actors in charcoal value chains, contributing to more sustainable management and improved capture of value by producers, traders and by the government. This work supports the developmen t of Zambia’s new national charcoal regulation – in line with the Forest Act of 2015 ‐ and is providing a pilot demonstration of practical steps to improve livelihoods. The work will also help to guarantee the supply of this critical source of energy ‐ so vital for income and food security ‐ without destroying forests
Evaluation FFF - Impact Analysis. Background Report 3.2
Full text linkDer Forschungsförderungfonds für die gewerbliche Wirtschaft (FFF) nimmt im österreichischen Innovationssystem eine zentrale Rolle ein. Eine seiner Hauptaktivitäten ist die Bereitstellung öffentlicher Mittel für industrielle F&E-Projekte. Diese Studie ist Teil einer größeren Evaluierung des FFF, vorbereitet durch das Ministerium für Verkehr, Innovation und Technologie (BMVIT). Es ist darauf ausgerichtet, die Muster der F&E-Finanzierung durch den FFF sorgfältig zu beschreiben und Parameter zu identifizieren, welche die Bereitstellung von Mitteln beeinflussen und die direkten, indirekten und breiteren Auswirkungen der FFF-Finanzierung darstellen. Es war daher eines der Hauptinteressen, das Konzept der Additionalität zu nutzen, um verschiedene (Additionalitäts-) Aspekte von Unternehmen zu analysieren, die vom FFF finanziert wurden
Defects in 3D Printing and Strategies to Enhance Quality of FFF Additive Manufacturing. A Review
No full textAdditive manufacturing technologies (or 3D printing) have emerged as potent tools in the creation of a diverse array of objects, promising a paradigm shift in production methodologies across industries. However, the benefits of these technologies can be diminished by the use of suboptimal parameters or inferior materials, leading to defects that significantly degrade the quality and functionality of the resulting products. An incomplete understanding of defect formation keeps under the formulation of effective preventative strategies. In light of this, our review provides a comprehensive exploration of defects that arise during the Fused Filament Fabrication (FFF)—one of the most prevalent 3D printing methods. The defects are systematically classified according to several key characteristics, including size, type, mode of occurrence, and location. Each common defect is extensively discussed, detailing its external manifestation, root causes, the impact on the properties of printed parts, and potential preventative measures. Our findings unveil the complex interplay of material properties, printing parameters, and cooling dynamics in the defect formation process. This classification holds significant practical relevance, providing a solid foundation for the development of strategies for defect minimization and quality improvement in 3D printed products. It offers valuable insights for a broad audience, including researchers exploring additive manufacturing technologies, 3D printing engineers, 3D printer operators, and quality assurance (QA) engineers involved in production quality control. Furthermore, our review delineates the path for future research in this domain. There is a crucial need for the development of advanced machine learning and artificial intelligence models that can predict defect formation based on given printing parameters and material properties. Future investigations should also focus on the discovery of novel materials and refining of printing parameters to achieve superior quality of FFF 3D printed products. This review serves as a cornerstone for these future advancements, promoting a deeper understanding of defect formation and prevention in additive manufacturing
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