Search results for "sublimation"
showing 10 items of 38 documents
Interrogating on the Essence of the Zombie World
2019
The chapter discusses critically the ontology of zombie world, as well as its interlink with the Thana-capitalism, as a new stage of capitalism where the Other’s death is gazed, consumed and preferred. The paradigm of the zombie world is debated in this chapter. In this respect, the culture of zombies situates in a futurist—apocalyptic—world, where technology and modern science have contributed to the end of mankind. The survivors not only struggle against zombies in a hostile world but also redeem the human nature according to two contrasting forces, the needs of survival which led to extreme individualism and the needs of re-foundation. The figure of the zombie represents the pauperized o…
Study of the chemically activated sublimation of ZnSe
1999
Abstract The reactions and processes involved in the growth of ZnSe by chemically activated sublimation in a H 2 atmosphere are studied. The rate of transport as a function of source and substrate temperatures and the difference between them are determined from close spacing vapour transport experiments. According to this process, ZnSe layers are deposited on sapphire substrates by short distance chemically assisted sublimation. The experimental results are analysed and the thermodynamic constants of the transport are determined using a theoretical model for kinetically controlled processes, assuming water to act as sublimation catalyst. A preliminary optical and structural characterisation…
Study and optimization of freeze-drying cycles of a model probiotic strain
2018
This work is based on the experimental study of the freeze-drying process to understand the impact of numerous factors on the survival rates of a model probiotic strain of Lactobacillus casei type. With the aim to find out if cell density in the matrix and survival rates are linked, we have studied the location of the cells after freeze drying inside a porous matrix composed of a lactose basis with a polymer, the polyvinylpyrrolidone (PVP) in various amounts. The best survival rate were obtained at slow freezing rate for a formulation containing 5% (m/V) of lactose and 5% (m/V) of PVP. Keywords: Freeze-Drying; Freezing; Probiotics; L. Casei ATCC 393
Heterobimetallicd—f Metal Complexes as Potential Single-Source Precursors for MOCVD: Structure and Thermodynamic Study of the Sublimation of [Ni(sale…
1998
Heterobimetallic [Ni(salen)Ln(hfa)3] species [H2salen and Hhfa being N,N′-ethylenebis(salicylideneimine) and hexa-fluoroacetylacetone respectively], where Ni(salen) acts as a neutral chelating ligand towards LnIII, form a series of isostructural compounds for Ln = YIII and any lanthanideIII cation from La to Yb. They are also isostructural with some of the [Cu(salen)Ln(hfa)3] compounds. They sublime without decomposition under vacuum which makes them potential single-source precursors in MOCVD. Sublimation, thermal behaviour, pressure and composition of the vapour phase versus temperature have been studied for the yttrium derivative, by means of thermal analyses, and mass spectrometry using…
Effects of heat treatments on the properties of copper phthalocyanine films deposited by glow-discharge-induced sublimation
2006
Copper phthalocyanine films have been deposited by glow-discharge-induced sublimation. The films have undergone postdeposition heat treatments in air at 250 and 290 °C for different times, ranging from 30 min to 14 h. The properties of as-deposited and heated films have been investigated by different techniques in order to determine the effects of heat treatments on the film properties. Fourier transform infrared analysis and UV−visible optical absorption analysis point out a gradual evolution of the film structure from a mixture of α and β polymorphs to the only β polymorph in the sample heated at 290 °C for 14 h. A pronounced decrease of carbon and nitrogen atomic percentages against an o…
Efficient Wide-Bandgap Mixed-Cation and Mixed-Halide Perovskite Solar Cells by Vacuum Deposition
2021
Vacuum deposition methods are increasingly applied to the preparation of perovskite films and devices, in view of the possibility to prepare multilayer structures at low temperature. Vacuum-deposited, wide-bandgap solar cells based on mixed-cation and mixed-anion perovskites have been scarcely reported, due to the challenges associated with the multiple-source processing of perovskite thin films. In this work, we describe a four-source vacuum deposition process to prepare wide-bandgap perovskites of the type FA1-n Cs n Pb(I1-x Br x )3 with a tunable bandgap and controlled morphology, using FAI, CsI, PbI2, and PbBr2 as the precursors. The simultaneous sublimation of PbI2 and PbBr2 allows the…
Thermal stability under air of tungsten–titanium diffusion barrier layer between silica and platinum
2014
Abstract The present work investigated the thermal stability of tungsten–titanium diffusion barrier layers intercalated between SiO 2 substrate and platinum thin film. The resulting structures were annealed under air in the temperature range 400–600 °C for annealing times up to 100 h. Chemical and structural characterizations at different stages of the treatment evidenced several phenomena occurring during annealing under air, especially the complete oxidation of the adhesive layer, the diffusion of tungsten oxide through platinum film at particle boundaries as well as the sublimation process of tungsten oxide. The results of film surface chemistry and microstructure were correlated with di…
Synthesis and thermoelectric properties of 2- and 2,8-substituted tetrathiotetracenes
2018
Reaction of elemental sulfur with 2-R1 and 2,8-R1,R2-substituted tetracenes (2) in refluxing DMF affords 5,6,11,12 tetrathiotetracenes (1) in good yields (74–99%) for a range of substituents where R1,R2 are: H,H (a); Me,H (b); MeO,H (c); Ph,H (d); Me,Me (e), iPr,Me (f, iPr = iso-propyl, CHMe2), Me,MeO (g); MeO,MeO (h). The reaction rate is limited only by the solubility of the tetracene (2); 2g–h being both the least soluble and slowest reacting. At partial conversion recovered single crystalline 2g led to its X-ray structure determination. Vacuum deposited (substrate deposition temperature 300 K, pressure 7 × 10−6 mbar, source temperature 500 K) thin films from 1 (of initial 88–99% purity)…
Jet-vortex spray freeze drying for the production of inhalable lyophilisate powders
2016
Abstract Spray-freeze-dried powders were suggested for nasal, epidermal (needle-free injection) or pulmonary application of proteins, peptides or nucleic acids. In spray-freeze-drying processes an aqueous solution is atomized into a refrigerant medium and subsequently dried by sublimation. Droplet-stream generators produce a fast stream of monodisperse droplets, where droplets are subject to collisions and therefore the initial monodispersity is lost and droplets increase in diameter, which reduces their suitability for pulmonary application. In jet-vortex-freezing, a droplet-stream is injected into a vortex of cold process gas to prevent droplet collisions. Both the injection position of t…
Light-Induced Sublimation of Cadmium Sulphide
1984
It has recently been shown that single crystal CdS, illuminated by light whose photon energy exceeds the bandgap, can eject particles from its surface while the temperature is well below the value required for vacuum sublimation. This phenomenon has obvious applications to the fabrication of surface structures as well as to the production of thin films that can show good CdS stoichiometry. This work will present several data on the morphology of the etched surface and its dependance on crystal orientation; results of an analysis of the recondensed thin film phase from the ejected material will also be shown. Emphasis will be devoted to examples of high resolution surface structures fabricat…