Search results for "Microscope"
showing 10 items of 1412 documents
Necking behavior of low-density polyethylene-isotactic polypropylene blends: A morphological investigation
1984
The tensile behavior of low-density polyethylene-isotactic polypropylene blends was investigated at room temperature. Neck formation and propagation along the whole length of the samples were observed for the whole range of composition. This behavior, which is not indicated by most data available in the literature, was examined in relation to sample morphology by scanning electron microscopy. The results of this investigation indicated some differences between the morphology of these materials and the morphology of blends which do not undergo necking propagation.
Investigations of polymerizable multilayers as gas separation membranes
1985
Abstract Polymerizable Langmuir—Blodgett (LB) multilayers of several diacetylenic amphiphiles were investigated on gas-permeable, polymeric supports. Macroscopically homogeneous multilayer films of hexacosa-10,12-diynoic acid and pentacosa-10,12-diyne phosphonate could be built up on polypropylene and polytetrafluoroethylene materials. As shown by scanning electron microscopy, the microscopic homogeneity of the built-up multilayers was mainly controlled by the surface structure of the support material, whereas the chemical nature of the support and photopolymerization of the layers did not affect the high order of the films. Such LB multilayers deposited on porous support materials are able…
Polymer Solidification under Pressure and High Cooling Rates
2000
Abstract Polymer solidification under processing conditions is a complex phenomenon in which the kinetics of flow, high thermal gradients and high pressures determine the product morphology. The study of polymer structure formed under pressure has been mainly made using conventional techniques such as dilatometry and differential scanning calorimetry under isothermal conditions or non isothermal conditions but at cooling rates several orders of magnitude lower than those experienced in industrial processes. A new equipment has been recently developed and improved to study the crystallization of polypropylene when subjected to pressure and cooled rapidly. An experimental apparatus essentiall…
Some Features of Polymeric Membranes for Water Purification via Membrane Distillation
2011
Polymeric membranes are currently adopted in water purification processes, such as reverse osmosis (RO) and membrane distillation (MD). This latter technique is very promising for separation effectiveness and energy savings. A valuable and effective MD unit must be equipped with polymeric membranes that exhibit specific properties, for example, hydrophobicity, a narrow pore size range, a high water penetration pressure, and a large vapor permeability. In this work, we present and examine the main features of membranes for MD processes, with the aim of experimentally evaluating the related performances. Scanning electron microscopy analysis was carried out for a first estimate of the pore si…
Multifunctional polyurethane foams with thermal energy storage/release capability
2020
In this work, polyurethane (PU) insulating panels containing different amounts of a microencapsulated paraffin with a nominal melting temperature of 24 °C, used as phase change material (PCM), were produced. The resulting panels behaved as multifunctional materials able to thermally insulate and simultaneously storing/releasing thermal energy near room temperature. The panels were characterized from a microstructural, thermal and mechanical point of view. Viscosity measurements highlighted an increase in the viscosity values of the PU liquid precursors due to the addition of the capsules, and this could lead to some difficulties during the production stages, especially in the mixing and foa…
Chemical compatibility of bulk alumina in flowing PbLi alloy under magnetic field
2021
Abstract Electrically insulating flow channel inserts (FCI) may be needed in liquid-based breeding blanket concepts to electrically decouple the metal flow from the strong magnetic field in a future fusion reactor. Although the magnetohydrodynamic simulation demonstrates a reduction of the pressure drop when a sandwich-like steel-alumina-steel FCI is employed, the tritium production efficiency in the breeding zone of a breeding blanket is limited to 550 °C due to the steel corrosion. Previous theoretical thermomechanical analyses point out the possible occurrence of induced interfacial stresses between the steel and the ceramic part. Both factors motivate the actual FCI development towards …
Probabilistic classification of intracranial gliomas in digital microscope images based on EGFR quantity
2009
A glioma is a type of cancer occurring, in the majority of cases, in the brain. The World Health Organization (WHO) assigns a grade from I to IV to this tumor, with I being the least aggressive and IV being the most aggressive. In glioma cells of grade IV the Epidermal Growth Factor Receptors (EGFRs) are over expressed. In this paper we hypothesize that this overexpression occurs also for gliomas of grades I to III. Moreover, we present a medical study aiming to determine the correlation between the WHO classification and the EGFR quantity in glioma tissue. We define five quantity classes for EGFR. First, results of immunohistochemical staining on brain glioma slices, which visualize the EG…
Effect of sintering process on color parameters of nano-sized yttria partially stabilized tetragonal monolithic zirconia
2018
Background Sintering process is responsible for aesthetic of zirconia restoration. This study evaluated the effect of different sintering temperatures and sintered-holding times on color parameters of monolithic zirconia. Material and Methods One hundred and thirty five zirconia bar specimens (width-length-thickness = 10×20×1.5 mm) were prepared from yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic and randomly divided into nine groups to be sintered at different temperatures [decreasing- (SD, 1350°C), regular- (SR, 1450°C), and increasing- (SI, 1550°C) sintering temperature] and different sintered-holding times [shortening- (HS, 60 min), regular- (HR, 120 min), and pro…
Influence of thermal tempering processes on color characteristics of different monolithic computer-assisted design and computer-assisted manufacturin…
2019
Background The optical properties of dental restoration were influenced by the sintering parameters. This study investigated the effects of different tempering processes on optical properties of three monolithic Cad-Cam ceramics. Material and Methods 135 monolithic material bars (4 mm width, 14 mm length, 1.2 mm thickness) were prepared from yttria-stabilized tetragonal zirconia polycrystalline (inCoris TZI, I), zirconia-reinforced lithium silicate (Vita Suprinity, V), and lithium disilicate glass (e.max CAD, E) ceramics, with different tempering processes through slow (S), normal (N), and fast (F) cooling (n=15). The color appearance (∆EW), translucency parameter (TP), contrast ratio (CR),…
Role of sintered temperature and sintering time on spectral translucence of nano-crystal monolithic zirconia
2018
Background Sintering process is accountable for aesthetic appearance of zirconia restoration. This study appraised the effect of different sintering procedure via sintered temperatures and sintering times on spectral translucence of monolithic zirconia. Material and Methods One hundred and thirty five monolithic zirconia specimens (width, length, thickness = 10, 20, 1.5 mm) were prepared from yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP, Ceramill®) and unintentionally divided into nine groups to be sintered at different temperatures [decreasing- (SD, 1350°C), regular- (SR, 1450°C), and increasing- (SI, 1550°C) sintering temperature] and different sintering times [shortening…