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Dimethyl fumarate (DMF) is an FDA-approved drug for treating relapsing-remitting multiple sclerosis; but it is susceptible to sublimation leading to its loss during processing. Cocrystals can protect against thermal energy via the interaction of DMF with a coformer via weak forces of interaction. With this hypothesis, we have, for the first time, prepared DMF cocrystals using the solvent evaporation method using coformers like citric acid and succinic acid screened by in-silico predictions and hydrogen bonding properties. Analysis using infra-red (IR), powder x-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and sublimation evaluation characterized cocrystals and their thermostability. Comparative analysis of the release profile has been done by dissolution and pharmacokinetic study of DMF and its cocrystals. The cocrystals have improved thermal stability and better pharmacological activities than DMF. In the safety and efficacy evaluation of the formulated cocrystals, they were found to be non-cytotoxic, antioxidant, and inhibiting IL-6 and TNF-α in PBMC induced by lipopolysaccharide (LPS). We have obtained cocrystals of DMF with improved thermal stability and better pharmacological activities than DMF. [Display omitted] • DMF cocrystals have been prepared using the slow evaporation method. • DMF cocrystals are more thermostable than DMF and less prone to sublimation. • DMF cocrystals have similar pharmacokinetics as DMF. • DMF cocrystals have better pharmacological activities than DMF. [ABSTRACT FROM AUTHOR]

Measurement of heat transfer coefficients (K v) is an important part of freeze-dryers characterization and as well a necessary step for executing any modelling. In most cases only an average value of K v is calculated, or an average value of center and edge vials is provided. Our aim is to go a step further and to describe the overall K v distribution various vial/ freeze drier combinations, whatever the pressure. From an experimental point of view, in this article we propose three methods to calculate the K v value for individual vials based on the ice sublimation gravimetric method. The first method we use is the most usual one, where the K v value is calculated based on the mass of sublimated ice and the product temperature measured in selected vias. In the second method, the average product temperature is estimated for each vial, based on the mass difference before and after sublimation and the K v value is calculated accordingly. In the third method, the K v is estimated by comparison to sublimation results from a simulation. Results from methods 2 and 3 are very similar results and are slightly different from those of method 1. Method 1 was shown to exhibit a systematic bias due to the fact that it is based on the temperature of recording of selected vials only, which are not representative for all positions. Once the individual values of K v have been calculated, it is possible to establish a distribution for each method. It was observed that an overlay of two normal distributions describing the center and the edge vials provides a good representation of the empirical distribution. Furthermore, we propose a holistic model aiming to calculate the K v distribution for any specified pressure. [ABSTRACT FROM AUTHOR]

In this work, tetrafluorinated titanyl phthalocyanines with F-substituents in both peripheral (TiOPcF 4 -p) and non-peripheral (TiOPcF 4 -np) positions were synthesized and characterized by the methods of elemental analysis, IR and electronic absorption spectroscopies. The influence of the position of F-substituents on the structure of TiOPcF 4 -p and TiOPcF 4 -np single crystals and thin films grown by vacuum sublimation was studied. TiOPcF 4 -p crystallizes in the I4/m space group and its molecules form uniform stacks along the tetragonal axis. Introduction of F-substituents to non-peripheral positions leads to the change of the crystal structure: TiOPcF 4 -np crystallizes in the P-1 space group and its molecules are packed into 2D layers. Both phthalocyanines form oriented polycrystalline films when deposited by thermal sublimation in vacuum, but their phase composition is different from that of single crystals. The effect of post-deposition annealing of TiOPcF 4 -p and TiOPcF 4 -np films on their phase composition, morphology, optical absorption and Raman spectra, as well as conductivity was revealed. It was shown that a phase transition, which led to the appearance of an additional band in the near-IR region in the optical absorption spectrum, was observed in TiOPcF 4 -p films when heated, whereas no phase transition was observed in TiOPcF 4 -np films. • Structure of single crystals and films of fluorinated titanyl phthalocyanines were determined. • The position of F-substituent affects the structure and phase composition of thin films. • Phase transition in thin films was studied by XRD and spectral methods. • Phase transition leads to the change in optical absorption spectra. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both CdZnTe (2 1 1) and (1 3 3) epitaxial films were prepared on GaAs (2 1 1) by Close Spaced Sublimation. • CdZnTe (2 1 1)/GaAs are the best stable interfaces at the initial nucleation stage. • At lower growth temperature, a more stable interface structure results in the film maintaining the same orientation as substrate. • At higher growth temperature, only (1 3 3) nucleus can reach the critical size and thus stabilize the growth. The origin and evolution of dual epitaxy in CdZnTe epilayer grown on GaAs substrates by close spaced sublimation has been studied, both (2 1 1) and (1 3 3) films are suitable for HgCdTe growth. And the effect of growth temperature on the orientation and crystalline quality of CdZnTe films has been investigated, more uniform orientation of adjoining growth islands in the growth of (1 3 3) film leads to a smoother surface with less threading dislocations and roughness. The interfacial properties of CdZnTe films were studied by the first-principles calculations combined with scanning transmission electron microscopy observations. By calculation the work of adhesion between the CdTe films and GaAs (2 1 1), obtain the CdTe (2 1 1)/GaAs (2 1 1) interface is the more stable interface structure at the initial nucleation stage. Combining to the results of experiment, at higher growth temperature, only (1 3 3) nucleus can reach the critical size and thus stabilize the growth. More importantly, the results on the dual epitaxy of CdZnTe films are expected to play a crucial role in guiding the dual epitaxy growth of other zincblende-type crystal. [ABSTRACT FROM AUTHOR]

The Cd 0.96 Zn 0.04 Te (211) crystal is widely recognized as the optimal substrate for epitaxy growth of HgCdTe material. However, its further application is significantly hindered by size and cost limitations. CdZnTe films grown on GaAs substrates by close spaced sublimation may present a promising substrate for epitaxial HgCdTe. In this work, we successfully prepared high quality CdZnTe (133) films on GaAs (211) substrate. The results of scanning transmission electron microscope and selected-area electron diffraction reveals different crystal orientation between GaAs and CdZnTe, which can effectively accommodate the large lattice mismatch. The crystalline quality of the CdZnTe film was improved by introducing a ZnTe buffer layer, resulting in reduction in the etch pit density from 3.2 × 105 to 2.6 × 105 cm−2; a decrease in the full width at half maximum from 57 to 34″, and a lower surface roughness from 9.88 to 3.69 nm. The incorporation of the ZnTe buffer layer prompt the formation of CuPt-type ordered CdZnTe regions at the interface between the CdZnTe film and ZnTe, efficiently relieving the misfit strain originating from GaAs and ZnTe interface. Additionally, a two-step growth method was employed to adjust the Zn content of the film surface by controlling the growth temperature. Diverse lattice constant CdZnTe film is ready to further epitaxial growth of HgCdTe material with different bandgap. • CdZnTe (133) epitaxial films were prepared on GaAs (211) by Close Spaced Sublimation. • High quality CdZnTe (133) films are prepared by introducing a Zn 1−x Cd x Te/ZnTe buffer layer. • The formation of a CuPt-type CdZnTe ordered regions effectively release the misfit strain. • A two-step growth of CdZnTe was employed to precise control over the Zn content in the films. [ABSTRACT FROM AUTHOR]

Understanding surface kinetics of SiO 2 growth on single crystal SiC at elevated temperatures is crucial to fabricate high-performance SiC-based devices. However, the role of oxygen in the evolution mechanism of SiC surface at atomic scale has not been comprehensively elaborated. Here, we reveal the manipulation effect of oxygen on the competitive growth of thermal oxidation SiO 2 (TO-SiO 2) and thermal chemical vapor deposition SiO 2 (TCVD-SiO 2) on the 4H-SiC substrate at 1500 °C. TO-SiO 2 is formed by the thermal oxidation of SiC, in which the substrate undergoes layer-by-layer oxidation, resulting in an atomically flat SiC/TO-SiO 2 interface. TCVD-SiO 2 growth includes the sublimation of Si atoms, the reaction between sublimated Si atoms and reactive oxygen, and the adsorption of gaseous Si x O y species. A relatively high sublimation rate of Si atoms at SiC atomic steps causes the transverse evolution of the nucleation sites, leading to the formation of nonuniform micron-sized pits at the SiC/TCVD-SiO 2 interface. The low oxygen concentration favors TCVD-SiO 2 growth, whose crystal quality is much better than that of TO-SiO 2 due to the high surface mobility in the thermal CVD process. We further achieve the epitaxial growth of graphene on 4H-SiC in an almost oxygen-free reaction atmosphere. Additionally, ReaxFF reactive molecular dynamic simulation results illustrate that the decrease in oxygen concentration can promote the growth kinetics of SiO 2 on single crystal SiC from being dominated by thermal oxidation to being dominated by thermal CVD. [ABSTRACT FROM AUTHOR]

It has been believed that stereo-irregular polymers hardly form crystalline structure because of the deficient ordering along the backbone direction. Here we show the crystallization of atactic polymers by rapid thermal quenching of polymers co-melted with a chain-stretching agent. To this end, crystalline PMMAs (hc-PMMAs) are prepared from stereo-irregular atactic-PMMAs (M n = 35–1500 kg/mol) as well as stereo-regular isotactic- and syndiotactic-PMMAs by rapid quenching of molten PMMA/benzoic acid (BA) solutions. BA acts as a chain-stretching agent. PMMA chains are elongated up to 60% of their contour length when they are co-melted with BA. The preferential hydrogen bonding between PMMA and BA compensates the conformational entropy loss of PMMA chains in molten PMMA/BA solutions. Upon quenching, PMMA chains are further stretched because of the large tensile stress induced by the sudden temperature drop and because of mechanical squeezing by concomitant directional crystallization of anisotropic lath-like BA crystals. After sublimation of BA, the PMMA shows a clear melting transition: T m = 276–283 °C for hc- s -PMMA and 293–306 °C for hc- a -PMMA. Unlike other conventional crystals having 3D crystallinity, hc-PMMAs exhibits 1D crystallinity due to ordered lateral packing between chains (d = ∼4.3 Å) which is independent on the tacticity while the packing is amorphous-like for the other two directions. For the reason of the reduced dimensionality in crystallinity, we named the crystalline PMMA as 1D hypo-crystalline PMMA (hc-PMMA). Because of their high 1D crystallinity (55–65%), hc-PMMAs exhibit the storage modulus (E ′) enhanced by 20 times comparing with those of pristine PMMA. [ABSTRACT FROM AUTHOR]

• Two major species (mono-oxo, di-oxo) occur within deposited ReO x on TiO 2 (P25). • Reversible T-dependent tuning of termination configuration of dispersed ReO x. • Mono-oxo species favored with increasing temperature at constant coverage. • Di-oxo species favored with increasing coverage at constant temperature. • Terminal stretching wavenumbers blue shift with increasing coverage. A holistic approach based on in situ molecular vibrational spectroscopy (Raman-FTIR and Raman-18O/16O isotope exchange) is applied to unravel the molecular structure and termination configuration of dispersed ReVIIO x on TiO 2 (P25) at surface densities of 0.16–2.5 Re/nm2 and temperatures of 120–430 °C. It is shown that the deposited ReVIIO x phase is heterogeneous, consisting of two distinct species: Species–I with mono-oxo termination configuration and Species–II with di-oxo termination configuration. A meticulous study of temperature and coverage effects shows that the mono-oxo Species–I prevails with increasing temperature and/or low surface coverage, whilst the di-oxo Species–II is favored at low temperature and/or high surface coverage. At constant coverage, a reversible temperature dependent di-oxo ↔ mono-oxo interconversion renders possible to tune the termination configuration of the majority deposited species. The wavenumbers of the mono-oxo and di-oxo terminal stretching modes undergo a blue shift with increasing surface coverage due to a cascade effect caused by the diversity of the support's hydroxyls' basicity. The wavenumber of the terminal ν Re = O mode of Species–I is at 1004 cm−1 for 0.48 Re/nm2 and gradually shifts to 1009 cm−1 for 2.5 Re/nm2; correspondingly, the symmetric stretching ν O = Re = O mode of the di-oxo Species–II is at 996 cm−1 for 0.48 Re/nm2 shifting to 1003 cm−1 for 2.5 Re/nm2. Above 275 °C part of the deposited ReO x phase is lost by sublimation. [ABSTRACT FROM AUTHOR]

Dans le cadre du présent travail, nous proposons d'appréhender l'épidémie mondiale de coronavirus de type COVID-19, en tant que phénomène sociobiologique. Pour mener à bien notre réflexion, nous nous appuierons sur une expérience d'écoute psychologique d'orientation psychanalytique menée lors des attentats de Nice ayant eu lieu en 2016, et poursuivie ce jour dans le contexte pandémique actuel. Plus précisément, nous nous pencherons sur le signifiant « victime », avec tout ce qu'il engage comme questionnements quant au sujet. Notre proposition sera de considérer le statut de victime comme une traversée. Au cours de cette dernière, il est important que la souffrance des sujets soit écoutée, reconnue, jugée et indemnisée. Et cela, afin que chacun puisse trouver sa façon singulière de donner sa réponse au réel du virus, tel qu'il s'est imposé à nous ; mais, nous verrons aussi que l'une des conclusions possibles de cette traversée consiste à passer par des formes diverses de sublimation. As part of this work, we propose to understand the global epidemic of COVID-19 coronavirus, as a sociobiological phenomenon. To carry out our reflection, we will base ourselves on a psychological listening experience (in a psychoanalytic orientation) conducted during the Nice attacks in 2016, and continued today, during the current pandemic context. More specifically, we will look at the signifier "victim", including all that it involves as questions about the subject. Our proposal will be to consider the victim status as a crossing. During this one, it is important that the suffering of the subjects is listened to, recognised, judged and compensated. In order for this to happen, everyone can find his own way of giving an answer to the reality of the virus, as it has imposed itself on us; but we will also see that one of the possible conclusions of this crossing consists in going through various forms of sublimation. [ABSTRACT FROM AUTHOR]

The so-called buffer layer (BL) is a carbon rich reconstructed layer formed during SiC (0001) sublimation. The covalent bonds between some carbon atoms in this layer and underlying silicon atoms makes it different from epitaxial graphene. We report a systematical and statistical investigation of the BL signature and its coupling with epitaxial graphene by Raman spectroscopy. Three different BLs are studied: bare buffer layer obtained by direct growth (BL 0), interfacial buffer layer between graphene and SiC (c-BL 1) and the interfacial buffer layer without graphene above (u-BL 1). To obtain the latter, we develop a mechanical exfoliation of graphene by removing an epoxy-based resin or nickel layer. The BLs are ordered-like on the whole BL growth temperature range. BL 0 Raman signature may vary from sample to sample but forms patches on the same terrace. u-BL 1 share similar properties with BL 0 , albeit with more variability. These BLs have a strikingly larger overall intensity than BL with graphene on top. The signal high frequency side onset upshifts upon graphene coverage, unexplainable by a simple strain effect. Two fine peaks (1235, 1360 cm−1), present for epitaxial monolayer and absent for BL and transferred graphene. These findings point to a coupling between graphene and BL. Image 1 [ABSTRACT FROM AUTHOR]

Spherical ZrB 2 -SiC powder with a eutectic phase was synthesised via induction plasma spheroidisation (IPS) in this study. The influence of H 2 flow and reaction chamber pressure on the powder microstructure was investigated during the induction plasma spheroidisation process. The powders have an evidently better fluidity (< 44 s/50 g) and a larger apparent density (>1.65 g/cm3) after IPS treatment. With an increase in H 2 flow or pressure, the shape of surface grains successively shows an irregular, hexagonal, and rectangular shape because the grain growth mechanism changes from surface energy to diffusion activation energy. There is serious mass loss of SiC on the surface because of pure active oxidation and sublimation during the IPS treatment. The cross section of the ZrB 2 -SiC powder indicates a dense microstructure comprising coarse ZrB 2 and intergranular eutectic phases. Furthermore, the corresponding ZrB 2 -SiC bulk ceramics and coating fabricated using the IPS-treated powder both contain eutectic phase. Unlabelled Image • The best fluidity and apparent density of powder is 21.116 s/50 g and 3.1024 g/cm3. • The ZrB 2 growth is controlled by surface energy and diffusion activation energy. • SiC loss is caused by sublimation, active oxidation of SiC and SiO 2 volatilisation. • The eutectic can improve the densification and properties of powder and coating. [ABSTRACT FROM AUTHOR]

• Impurity-induced 2D phase forms on Bi 2 Se 3 surface during submonolayer In deposition. • Islands of indium-induced surface phase have a height of 0.4 nm. • During indium deposition, area of the surface phase increases until complete coverage. • The phase locally suppresses sublimation, which creates multilayer star-shaped islands. Using in situ reflection electron microscopy, transformations of Bi 2 Se 3 (0001) surface during In deposition have been studied. We first report the formation of an In-induced surface phase that precedes nucleation and growth of a layered In 2 Se 3 at substrate temperatures around 400 °C. The surface phase nucleates on Bi 2 Se 3 (0001) terraces as islands having high In content and a height of 0.4 nm. During continuous In deposition, the area of these islands increases and suppresses Bi 2 Se 3 sublimation from the regions covered by the In-induced surface phase. This locally suppressed sublimation and sublimation-induced ascending motion of Bi 2 Se 3 atomic steps create multilayer triangular star-shaped islands. [ABSTRACT FROM AUTHOR]

An interpretable machine learning model for predicting the melting behaviors of energetic materials has been developed, using precise experimental and computational data. [Display omitted] • Interpretable machine learning reveals hidden mechanisms for melting behaviors. • Melting point and melt-castable property of energetic compounds are studied. • The best model demonstrates prediction accuracy over 85 %. • Model interpretation provides physicochemical insights. Melting behaviors of energetic compounds determine their thermo-responsive properties, which affects the manufacturing operations and structural stabilities. However, the decisive physicochemical mechanisms for melting behaviors of energetic compounds are absent, which hurdles the acceptancy and generalization of prediction models for rational molecular design. Herein, an interpretable machine learning (IML) approach was proposed to construct accurate prediction models for melting point values and melt-castable potentials of energetic compounds. A high-quality melting-point dataset comprising 239 neutral CHNO compounds was obtained, and the data was collected with strict criteria involving chemical formulations, crystal structures and experimental measurement operations. Tailored descriptors, which involve the priori insights for melting behaviors, were adopted for IML algorithms. The extreme gradient boosting model presents the best prediction accuracy (85 %) for the classification of melting point values between 273 K and 650 K; while 87 % accuracy is achieved for the classification of melt-castable property. Importantly, model interpretation assists to reveal that the close contacts between OC and NC, dipole, oxygen balance and the cohesive energy are decisive features for melting point prediction; while enthalpy of sublimation and polar surface area are paramount for the identification of melt-castable property. The ability to determine melting behaviors using IML will broaden the high-throughput screening of energetic compounds and offer valuable guidance towards molecular design. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) plays a vital role both as a reactant in petrochemical processes and as an energy carrier and storage medium. When produced from carbon-containing feed stocks, such as fossil fuels and biomass, hydrogen is typically produced as a mixture with carbon dioxide (CO 2), and must be subsequently separated by the associated energy, with an invertible energy penalty. In this study, the process for the removal of carbon dioxide from CO 2 - H 2 mixtures by de-sublimation was analysed. This process is particularly relevant to the production of liquid hydrogen (LH 2) at cryogenic temperatures, for which cooling of the H 2 stream is already necessary. The solid – gas equilibrium of CO 2 - H 2 was studied using the Peng-Robinson equation of state which provided a wide range of operating conditions for process simulation. The de-sublimation process was compared with selected conventional separation processes, including amine-based absorption, pressure swing adsorption and membrane separation. In the scenario in which the resulting products, carbon dioxide and hydrogen, were subsequently liquefied for transportation and storage at 10 bar and −46 °C, and 1 bar and −251.8 °C, respectively. The overall energy consumption per kg of CO 2 separated (MJ/kgCO 2) , was found to follow the order: 8.19–11.21 for monoethanolamine (MEA) absorption; 1.81–8.93 for membrane separation; 1.53–5.69 for pressure swing adsorption; and 0.81–3.35 de-sublimation process. Each process was evaluated and compared on the bases of electricity demand, cooling water usage, high-pressure steam usage, and refrigeration energy requirements. Finally, the advantages and disadvantages were discussed and the feasibility and sustainability of the processes for application in the production of liquid hydrogen were assessed. Image 1 • Four approaches for CO 2 - H 2 separation were analysed. • Energy consumptions follows: MEA absorption > membrane separation > PSA > de-sublimation. • De-sublimation was proved having advantages when liquid as target products. • The advantages and disadvantages, the feasibility and sustainability were assessed. • Phase equilibrium analysis was conducted for a range of CO 2 /H 2 compositions. [ABSTRACT FROM AUTHOR]

The widespread commercialisation of proton exchange membrane fuel cell (PEMFC) for either transportation or stationary application is still hindered by cost barriers owing to the use of precious metal catalysts, as well as performance and material related insufficient durability. Therefore, it is important to enhance the platinum utilization as well as optimize the fabrication method for the production of membrane electrode assemblies (MEAs). This study demonstrates that the drying step during the electrode manufacturing directly affects the microstructure of the catalyst layer, having inherent influence on the porosity and the platinum utilization during PEMFC operation that greatly affects the performance. Freeze-drying as a novel drying technique for PEMFC electrodes is proposed for preparation of low Pt-loaded cathodes (0.160 mg Pt ·cm−2). This technique possesses the unique feature of solvent removal via sublimation and not only generates 3.5-fold higher effective porosities but also increases the electrochemical surface area by 1.5 times when comparing to electrode dried by regular oven drying technique. Additionally, freeze-drying of electrode also improved ionomer distribution, as evident from a reduced resistance between the pores and a reduced electrolyte resistance of the catalyst layer. Consequently, we consider freeze-drying to be a highly promising technique for future production of MEAs. Image 1 • Drying step in catalyst layer preparation significantly impacts cell performance • Freeze-drying allows greatly increasing porosity of catalyst layer • Freeze-dried electrodes exhibit reduced mass transport losses • Freeze-drying is applicable to different suspension coating techniques [ABSTRACT FROM AUTHOR]

Abstract A theoretical model of the Cd/Zn interdiffusion during the growth of different sequences of ZnTe/CdTe layers was developed. The model can predict the values of the growth parameters needed to obtain desired composition profiles from specific ZnTe/CdTe multilayer growth sequences. With these simulations as a guide, Cd x Z n1 - x Te graded composition samples with different Cd profiles and thicknesses were grown. A good agreement was found, demonstrating the possibility of preparing different and predictable Cd content profiles in Cd x Zn 1-x Te graded thin films by the simple isothermal close space sublimation method. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The well-aligned and highly-conductive carbon nanofibers were prepared. • The addition of AM-MWNTs possessed preferable capacitive performance than AC-MWNTs. • The flexibility of electrode was improved by the sublimation of terephthalic acid. • The hierarchical nanostructure led to excellent electrochemical performance. Abstract The highly flexible carbon nanofibers mixed with differently functionalized carbon nanotubes (MWNTs) and terephthalic acid (PTA) were fabricated and further applied as a binder-free electrode. The addition of AM-MWNTs possessed higher electrical conductivity and preferable capacitance performance than that of AC-MWNTs due to its better-aligned carbon architectures. Attributed to the sublimation of PTA in carbonization, the resulted self-sustained nano-films exhibited desirable electrochemical performances as high capacitance, good rate capability and excellent cycling stability. By virtue of the lightweight, flexibility and simplicity of operation, the self-sustained nanocomposite electrode we demonstrated will surely favor its application for the development of flexible energy storage devices. [ABSTRACT FROM AUTHOR]

• Beeswax parts of an artefact have been examined. • Quantification of degradation products was carried out by FTIR spectroscopy, Py-GC/MS analysis and DSC measurements. • The results support the theory of sublimation of n-alkanes from beeswax during ageing. This study is devoted to the statue of St. Ursula from the depositary to the Slovak National Museum–Červený Kameň Castle. It is a heavily damaged, slightly under life-size seated female statue from the 2nd half of 19th century. The artefact is very heterogeneous and degraded. The wax parts have been examined with the aim of detecting and quantifying degradation products using FTIR spectroscopy, Py - GC/MS analysis and DSC measurement. The results obtained were compared with the degradation studies from available literary sources. The most important achievement is that the results support the theory of sublimation of n-alkanes from beeswax during ageing. The degradation mechanisms taking part during ageing are hydrolysis and oxidation. The suggested methods of accelerated ageing could be a suitable simulation of natural ageing. The experimental methods employed are complementary and enable to follow the progress of beeswax degradation. [ABSTRACT FROM AUTHOR]

Highlights • Equilibrium vapor pressure of CH 3 NH 3 Br was measured in the range of 433–503 K. • Standard enthalpy of sublimation of CH 3 NH 3 Br at 298.15 K is 196.7 ± 2.8 kJ·mol−1. • Standard entropy of sublimation of CH 3 NH 3 Br at 298.15 K is 280.0 ± 5.6 J·mol−1 K−1. • Standard entropy of the crystalline CH 3 NH 3 Br at 298.15 K is 160.2 ± 5.6 J·mol−1 K−1. Abstract The equilibrium vapor pressure of methylammonium bromide was measured as a function of temperature in the range of 433–503 K. Standard enthalpy and entropy of sublimation of CH 3 NH 3 Br at 298.15 K and 1 atm were determined as (196.7 ± 2.8) kJ·mol−1 and (280.0 ± 5.6) J·mol−1 K−1, respectively. The measured value of sublimation enthalpy was found to be in agreement with that directly calculated from the available thermodynamic data. Standard entropy of the crystalline CH 3 NH 3 Br at 298.15 K was determined for the first time as (160.2 ± 5.6) J ·mol−1 K−1. [ABSTRACT FROM AUTHOR]

Abstract The sublimation of terbium and lutetium triiodides was studied by Knudsen effusion mass spectrometry. The temperature dependencies of partial vapor pressures [atm] of the monomer and dimer molecules were determined as: ln p (TbI 3) = – (31.74 ± 0.24)× 103/ T + (21.43 ± 0.29) for 743–906 K; ln p (Tb 2 I 6) = – (38.66 ± 0.38)× 103/ T + (25.63 ± 0.46) for 786–906 K; ln p (LuI 3) = – (31.48 ± 0.25)× 103/ T + (22.28 ± 0.30) for 721–951 K; and ln p (Lu 2 I 6) = – (36.95 ± 0.37)× 103/ T + (25.21 ± 0.43) for 796–950 K. On the basis of a joint analysis of all literature data, the sublimation enthalpies [kJ mol–1] at 298.15 K are recommended as 281 ± 3 (TbI 3), 346 ± 30 (Tb 2 I 6), 279 ± 12 (LuI 3), and 340 ± 30 (Lu 2 I 6). The standard formation enthalpies [kJ mol–1] of the gaseous species at 298.15 K are –343 ± 4 (TbI 3), –902 ± 30 (Tb 2 I 6),–326 ± 12 (LuI 3), and –870 ± 30 (Lu 2 I 6). Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract A new method of solubility estimations, applied to sparingly dissolved compounds in supercritical carbon dioxide has been introduced in this paper. The method is based on determination of solubility contributions along the thermodynamic path consisting of sublimation and solvation processes. The contribution of the sublimation process is taken from the experiment, while the free energy of solvation is calculated from the classical density functional theory based on the fundamental measure theory. The parameterization of potential was performed using the Weeks-Chandler-Anderson procedure, where the Lennard-Jones parameters were obtained from the thermodynamics data of solute and solvent critical points. The introduced method can efficiently predict the pressure crossover on solubility curve of sparingly dissolved compounds in supercritical carbon dioxide. Highlights • We developed the new method of solubility estimations for drug compounds. • The method is based on the classical density functional theory. • We obtained two crossovers on solubility curve of ibuprofen in scCO 2. [ABSTRACT FROM AUTHOR]

Abstract Obtaining SiC ceramics with high physical and mechanical properties requires the use of high purity products with a single crystal structure of particles. Such a product can be obtained by the plasma dynamic synthesis based on using a pulsed arc discharge. This paper presents that the way of an arc discharge ignition significantly influences both the effectiveness of the precursor sublimation and the phase composition of the final ultradispersed product. The arc discharge ignition through a thermal breakdown mechanism is the most efficient way to implement the plasma dynamic synthesis of silicon carbide β-SiC and achieve its yield up to ~99 wt% of the product. The synthesized powder is characterized by a single crystal structure of particles and their average size of ~70 nm. Spark plasma sintering of the as-prepared materials allows improving the ceramics quality in comparison with the ceramics sintered from the commercial silicon carbide. This effect is especially observed at sintering the ceramics with the use of Al-B-C additives, when the higher mechanical characteristics (ρ = 98.8%, H = 26 GPa) are achieved. Highlights • Ultradispersed SiC is synthesized by plasma dynamic method with the yield of ~99 wt%. • The SiC purity depends on the effective precursor sublimation and plasma ignition way. • As-prepared SiC powder contains single crystal particles with an average size of 70 nm. • SPS ceramics based on this SiC has both high density (~99%) and hardness (~26 GPa). [ABSTRACT FROM AUTHOR]

Abstract Mechanical polishing treatment was carried out on polycrystalline CdZnTe thick films grown by close-spaced sublimation method. The influence of Al 2 O 3 polishing powder particle sizes (2.5 μm, 1 μm and 0.05 μm) and polishing durations (1 h, 2 h and 3 h) on the structure, surface morphology and electrical performances of the CdZnTe thick films was studied by XRD, EDS, SEM, AFM and I-V characterization systems. The results showed that the reduction of the particle size of the polishing powder and the appropriate increase of the polishing time length could improve the surface roughness, surface defects and leakage current of the CdZnTe sample. Highlights • High quality CdZnTe thick film was prepared by close-spaced sublimation method. • The films were polished with different Al 2 O 3 particle sizes and polishing durations. • Mechanical polishing improved surface topography and reduced the defects of films. • Low leakage current and high UV sensitivity of detectors were obtained by polishing. [ABSTRACT FROM AUTHOR]

Abstract Equipment capability is an important factor in scale up and technology transfer for lyophilized pharmaceutical products. Experimental determination of equipment capability limits, such as the maximum sublimation rate at a given chamber pressure, is time-intensive for production lyophilizers. Here, we present computational fluid dynamics modeling of equipment capability and compare it with experimental data for minimum controllable pressure ice slab sublimation tests in a 23 m2 shelf area freeze dryer. It is found that the vapor flow in the production scale is characterized by turbulent effects at high sublimation rates. For the considered freeze dryer configuration, the onset of turbulence occurs at a sublimation rate of 17 kg/h and leads to an increase in the minimum controllable pressure by 3-4 mTorr for the flow rates up to 40 kg/h. Variations in the shelf and duct orientations as well as the valve stroke distance and their effect on the equipment limit and pressure uniformity are also discussed. The minimum controllable pressure measured experimentally agreed within 5% with computational fluid dynamics results. For high vapor sublimation rates at final stages of ice slab testing, the condenser load affects the product chamber pressure control. Estimate of condenser pressure changes because of ice accumulation has been included. [ABSTRACT FROM AUTHOR]

Abstract The use of co-solvent systems can benefit the freeze-drying process and product performance. In this study, cycle designs were applied based on existing recommendations for water-based formulations. Modifications thereof and the influence on the process (e.g., drying times) and product quality attributes (e.g., product appearance, residual solvent) were tested for various cosolvent systems. It was found that fast freezing was associated with the formation of large crystals for 50 mg/g polyvinylpyrrolidone in 40% 1,4-dioxane (w/w), resulting in a 7% reduction of primary drying. The application of high shelf temperatures during primary drying for 50 mg/g polyvinylpyrrolidone in 70% tert -butanol was feasible, resulting in shorter primary drying times but high residual solvent levels (7.7%). Most notable was that the inclusion of an evaporation step after freezing improved the product appearance for low-melting co-solvents (10% ethanol and 10% acetone). No ice or solvent nucleation occurred in the case of 50 mg/g mannitol in 50% N , N -dimethylacetamide during the normal freezing stage. Instead, the solution viscosity significantly increased after cooling to low shelf temperatures, followed by product evaporation (rather than sublimation) during the drying phase and failure to form a product cake after drying. The application of annealing enabled nucleation and sublimation. [ABSTRACT FROM AUTHOR]

Graphical abstract The first heterometallic Na–Cu fluorinated diketonate complex is reported and structurally characterized by X-ray crystallography. Abstract The unsolvated Cu(II) complex with bis(pentafluorobenzoyl)methanide ligand (L, C 6 F 5 COCHCOC 6 F 5 −) is prepared and crystallized as [CuL 2 ] (1) using gas phase sublimation-deposition at 150 °C. The X-ray crystallographic characterization confirmed the centrosymmetric mononuclear structure of 1 with a square planar geometry around Cu(II) (Cu–O av 1.9149(8) Å). The reaction of 1 with sodium hexafluoroacetylacetonate [Na(hfac)] in a solvent-free environment afforded [Na 2 Cu 2 L 4 (hfac) 2 ] (2), the first heterometallic Na–Cu β -diketonate characterized by single-crystal X-ray diffraction. In the centrosymmetric tetranuclear structure of 2 , a dimeric [Na(hfac)] 2 unit is sandwiched between two CuL 2 units. The L-ligands function as chelating-bridging between Cu and Na through one of their O-atoms. The hfac ligands are chelating-bridging between Cu and Na and between Na(1) and Na(1A) through both O-atoms. In addition to the five primary Na–O interactions (av. 2.4109(17) Å), three secondary Na–F contacts (av. 2.6006(15) Å) contribute to the overall distorted square antiprismatic coordination environment for Na. The geometry of Cu is square pyramidal with Cu–O(L) distances averaging at 1.922(14) Å and Cu–O(hfac) of 2.3021(15) Å. Thermal decomposition of 2 yields a mixture of NaCuF 3 , Na 2 CuF 4 and NaF, when conducted at 230 °C in argon at ambient pressure. [ABSTRACT FROM AUTHOR]

Abstract We report a high efficiency antimony selenide (Sb 2 Se 3) photovoltaic device structure using a new multi-step close space sublimation deposition process incorporating a Sb 2 Se 3 seed layer; key to achieving higher efficiency devices via close space sublimation. Utilizing a glass|FTO|TiO 2 |Sb 2 Se 3 |PCDTBT|Au structure, a peak efficiency of 6.6% was achieved, which is comparable to the current record devices for this material. Crucially, this device avoids toxic lead in the hole transport material, and cadmium in the window layer. Moreover, the addition of the PCDTBT back contact both maintains peak efficiency of 6.6%, and improves the uniformity of performance, increasing the average efficiency from 4.3% to 6.1%. Graphical abstract fx1 Highlights • 6.6% efficient antimony selenide photovoltaic devices. • High efficiency photovoltaic devices without toxic lead or cadmium. • A seed layer is a crucial step for high quality CSS antimony selenide films. • Incorporation of an organic PCDTBT layer improves uniformity of performance. [ABSTRACT FROM AUTHOR]

Abstract V-doped semi-insulating (VDSI) SiC crystal is a promising substrate for high-frequency electronic devices achieved using GaN epitaxial films. However, V doping in a SiC crystal is difficult to control owing to the different sublimation temperatures of VC and SiC. The amount of V changes depending on the growth sequence, which has been a significant concern in VDSI SiC substrates in terms of wafer reliability. In this study, therefore, we aimed to synthesize a single source by vaporizing Si, C, and V under the same conditions to improve the doping issue in VDSI SiC. We synthesized V-doped SiC powder as the starting material for VDSI SiC substrate based on thermodynamic modeling, and the synthesized powder was used to grow a VDSI SiC crystal via physical vapor transport. Finally, considering the homogeneous V concentration in the grown crystal, the synthesized V-doped SiC was observed to be effective to grow VDSI SiC independent of the growth sequence. [ABSTRACT FROM AUTHOR]

This study examines the differences in using two primary methods for adsorbing trimethylphosphine oxide (TMPO) onto acid catalysts and their influence on the NMR spectra of TMPO-loaded zeolites. The findings show that TMPO molecules interact with both Brønsted and Lewis acid sites, and that the amount of (TMPO) 2 H+ dimers formed increases with the amount of TMPO added. The use of dichloromethane as a solvent inhibits the formation of dimers and crystalline TMPO but may lead to inaccurate estimations of acid site strength and quantification due to interactions with residual solvent molecules. The gas-phase method is preferred for adsorbing TMPO onto zeolites, but caution is needed to avoid forming a high number of dimers that ca pose challenges in the interpretation of the NMR spectra. [Display omitted] • TMPO was successfully adsorbed onto HZSM-5 zeolites using dichloromethane as solvent and through sublimation of TMPO. • Even under high vacuum conditions, it is difficult to remove solvent molecules from zeolite pores. • The presence of residual solvent molecules adds significant complexity to the interpretation of NMR spectra. • The gas-phase method is superior for adsorbing TMPO as it eliminates interactions with residual solvent molecules. [ABSTRACT FROM AUTHOR]

Engineered, condensational growth of aerosol particles is a well-established technique incorporated into particle detection and sampling systems. It is typically accomplished through passage of particles through controlled temperature, supersaturated systems with moderate-to-high vapor pressure compounds, which are liquid at room temperature. However, there are instances where it is advantageous to intentionally grow particles with room temperature, low vapor pressure (<10−3 Pa) solid compounds, either as part of particle collection or ionization systems. Sublimation-condensation, though demonstrated previously, is much less examined, particularly for nanoparticle growth. In this study, we examine a thermally diffusive, laminar flow sublimation-condensation system, wherein solid organic powders (all ionization facilitating matrices) are sublimated at moderate temperature (70–130 °C) and subsequent cooling results in vapor supersaturation, promoting growth of particles. The extent of particle growth was characterized via tandem differential mobility analyzer (TDMA) measurements, with 30 nm–200 nm particles. The grown diameter distributions were monitored for three different low vapor pressure organic solids at variable sublimator temperature settings. We found optimized operating conditions enabled particle growth above diameters of 500 nm. Growth experiments with 7 nm protein (transferrin) particles using ferulic acid as the working solid additionally yielded grown particles in excess of 200 nm in diameter. However, we also found heterogeneous growth occurred simultaneously with homogeneous nucleation of the working solid, which could not be avoided if growth to diameters >500 nm was desired. Homogeneously nucleated particles were broadly distributed in size, and generally smaller than the test particles grown by condensation, but still with diameters in excess of 100 nm. While SEM images of grown particles revealed smooth surfaces not indicative of agglomeration with homogeneously nucleated particles, we cannot rule out the contribution to growth of homogeneously nucleated particle coagulation with sampled particles in the growth system. By comparing to numerical simulations, we use TDMA measurements to estimate effective vapor pressures for the tested sublimated solids, assuming growth occurred solely by vapor condensation. Simulations suggest that saturation ratios in excess of 102 are needed for nanoparticle growth. • A laminar flow sublimation-condensation system is designed • Tandem DMA experiments are performed with three low vapor pressure solid materials • Numerical simulations are performed to predict particle growth rates • Nanoparticles grow >500 nm with low vapor pressure working solids [ABSTRACT FROM AUTHOR]

• CdZnTe (2 1 1)/GaAs epitaxial films were prepared by Close Spaced Sublimation. • The effect of temperature on the crystalline quality of CdZnTe films has been investigated. • CdZnTe films with a low dislocation density were obtained. Cd 0.96 Zn 0.04 Te crystals are perfect substrates for epitaxial growth of HgCdTe films due to good lattice matching, but they are limited by cost factors. To grow a replacement substrate for the subsequent growth of low-cost, high-yield HgCdTe IR materials, CdZnTe epitaxial films have been fabricated by close-spaced sublimation on GaAs substrates, and the effect of substrate temperature on the crystalline quality of CdZnTe films has been investigated. The results of EBSD and TEM indicate that the surface is oriented in (2 1 1) and the low temperatures enhance the crystalline quality of the film. The results of dislocation density (average etch pit density ∼3.6 × 105 cm−2) and energy dispersive spectrometer (Zn content ∼5 %) indicate that CdZnTe films with appropriate Zn content and excellent crystal quality can be obtained by the close spaced sublimation method, which is expected to be applied for molecular beam epitaxy growth of HgCdTe films. [ABSTRACT FROM AUTHOR]

Antimony selenide (Sb 2 Se 3 ) based thin film solar cells have recently drawn a growing research interest due to their increasing power conversion efficiency, proper bandgap, high absorption coefficient, and earth abundant nature. Herein, the Sb 2 Se 3 thin films were prepared by close spaced sublimation (CSS) for efficient Sb 2 Se 3 solar cells. The origin and the mechanisms of shunt current were analyzed. Non-ohmic space-charge limited current (SCLC) was identified to be an important contribution to the nonlinear shunt current in Sb 2 Se 3 thin film solar cells. To tackle this issue, a high-resistance SnO 2 buffer was introduced at the front contact. With the insertion of a SnO 2 buffer, the micro-shunt paths were modified and a significant efficiency improvement to 5.18% was obtained. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Sublimation enthalpies are predicted using electrostatic potential model. • Model provides a good agreement with experiment except for 1-aminoadamantane. • Discrepancy may be due to not totally crystalline phase of 1-aminoadamantane. • Plastic crystals should be rejected in developing the estimation methods. Abstract The sublimation enthalpy of 1-aminoadamantane was estimated using the molecular electrostatic potential (MEP) model. An equation has been proposed that describes the relationship between the sublimation enthalpy and computed crystal density, molecular surface area plus four quantities obtained from the surface electrostatic potential. The coefficients in this equation were determined from least-squares fitting to reliable values of sublimation enthalpy of 23 adamantanes. The sublimation enthalpies estimated by MEP model agree within 4 kJ⋅mol−1 for all compounds, except for 1-aminoadamantane. The reason for a large difference between experimental and estimated sublimation enthalpy of 1-aminoadamantane is discussed. [ABSTRACT FROM AUTHOR]

Highlights • Electrical performance of Cu doped CdTe thin films show better than Ag doped films to some extent. • J-V characteristics demonstrates the preference of thermal annealing for higher efficiency. • C-V measurement reveals low acceptor concentration of 1.5 × 1014 cm−3. • Laser annealed samples suggest stricter control of laser energy and focus to improve efficiency. Abstract Copper (Cu) and silver (Ag) are the potential dopants that could enhance p-type doping of polycrystalline cadmium telluride (CdTe) thin films to be used in CdTe based solar cells. In this work, the effect of doping concentration of Ag and Cu in both thermal and laser anneal process of doping to CdTe thin film solar cells' electrical performance were investigated. CdTe thin films of 3 µm thickness were deposited using the close-spaced sublimation (CSS) process and subjected to Cu and Ag doping process through dip coating in copper (II) chloride (CuCl 2) and silver nitrate (AgNO 3) solution, respectively at different concentration range followed by either thermal or laser annealing. Thermally annealed CdTe thin films were treated in convection oven, whereas laser annealing was carried out by illuminating the samples with pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser at wavelength of 532 nm. Fabricated solar cells were electrically characterized by light current-voltage (J-V) and capacitance-voltage (C-V) measurements. J-V measurement demonstrates that Cu doped CdTe solar cells are having better electrical performance as compared to Ag doped ones. The effect of increasing dopant solution concentrations seems to have consistent trend with the increase of J-V parameters as identified in this work. C-V measurement shows that Cu doped CdTe films has higher doping capability with the highest acceptor concentration of 1.5 × 1014 cm−3 compared to Ag doped CdTe films of 8.1 × 1013 cm−3. In addition, laser annealing finds lower J-V performance and acceptor concentration of Cu and Ag doped CdTe solar cells with limitations in smaller process space for surface annealing as well as optimization. [ABSTRACT FROM AUTHOR]

Abstract The volatilization and condensation behaviours of magnesium during the sublimation and desublimation processes were investigated at 10 Pa, respectively. The average volatilization rate increases with increasing temperature, but decreases with increasing specific surface area. The condensation position at which the magnesium vapor becomes solid is further away from the heating source with the temperature of the heating source increasing, but the value of the condensation temperature is maintained in an interval (603–733 K). It can be beneficial to the condensation and crystallization of magnesium vapor with increasing the temperature and temperature gradient of the condensing zone appropriately. Highlights • A novel experimental method to study metal vapor condensation, the interaction of magnesium vapor with non-condensable gas, which also applies to other metal vapors. • The effects of pressure, condensation temperature and temperature gradient on the condensation of magnesium vapor were investigated. • The volatilization and condensation behavior of magnesium vapor is of great significance to the reverse reaction problem in the process of preparing magnesium metal by vacuum carbothermal reduction. [ABSTRACT FROM AUTHOR]

Knowledge of the vapor pressures and the sublimation/vaporization enthalpies of a metalorganic precursor can be indispensable for optimizing a deposition process. Unfortunately, published measurements of those values are often referred to a unique temperature, and comparing such studies requires adjusting the data to a common temperature. We tested four methods to adjust the difference between the heat capacities of the gaseous and condensed phases to the reference temperature 298.15 K. The tests used published data for the well-studied compound, ferrocene, as well as new data for the vapor pressure measured by the transpiration method in the range from 361 K to 435 K. The agreement among the four methods suggests that they will be reliable for other metal containing complexes for which limited thermodynamic data are available. [ABSTRACT FROM AUTHOR]

The early stages of close spaced sublimation growth of CdZnTe(0 0 1)/GaAs(0 0 1) epilayer were experimentally studied under different substrate temperatures and ambient pressures. SEM, AFM, XRD, EBSD and EDS were used for the characterization of morphology, structure and composition of the films. The films were found to be (0 0 1) oriented and epitaxial in nature with zinc blende cubic structure. Deposition models were used to explain the correlation between growth condition and CdZnTe island morphology. Films grown at 350 °C and 1 × 10 2  Pa show the best uniform and smooth surface. When increasing substrate temperature to 430 °C or ambient pressure to 1 × 10 4  Pa or 3 × 10 4  Pa, islands are less compact and exhibit preferential growth along one of 〈1 1 0〉 directions, which could be resulted from the big lattice mismatch (14.0%) of Cd 0.9 Zn 0.1 Te(0 0 1)/GaAs(0 0 1) heterojunction. For the growth at 430 °C in 3 × 10 4  Pa, prior nucleation at defect site was found, and the appearance of regular 〈0 1 0〉 oriented island edges proposes that steps 〈0 1 0〉{1 0 0} are more stable for CdZnTe(0 0 1)/GaAs(0 0 1) epilayer than steps 〈1 1 0〉{1 1 1}. [ABSTRACT FROM AUTHOR]

A facile one step method was developed for dyeing polypropylene fabrics with hydrazono propanenitrile disperse dyes under both aqueous and supercritical carbon dioxide mediums. The dyeing was carried out without any modification of the fabric and the results were compared. The dyeing parameters, mainly, dyeing concentration, temperature, time, and pressure in both water and scCO 2 mediums were studied. Also, the dye uptake expressed as colour strength (K/S) was measured for both dyeing mediums and it was observed that colour strength of the dyed polypropylene fibers in scCO 2 was significantly better than in water. The fastness properties (washing, rubbing, light and sublimation) of dyed samples in scCO 2 and water exhibited very good results. The ATR-FTIR of dyed samples in water and scCO 2 were found to be in good agreement with the structure of the dyestuff under application. [ABSTRACT FROM AUTHOR]

The study outlined in this article was carried out within the framework of ESA's PROSPECT programme, which will provide both a sample drill and miniaturised mass spectrometer system for flight on-board the planned Russian Luna-27 mission to the lunar south pole. There, it aims to collect samples of regolith, containing water ice and other volatiles, and to make isotopic and abundance measurements to fingerprint the source(s) of these volatile species. However, it is necessary to first consider how any localised temperature increases during sample acquisition activities may result in water ice loss via sublimation and thus isotopic modification of the remaining residual ice. To attempt to address these concerns, a suite of sublimation experiments was conducted at the Laboratoire de Géologie de Lyon, where a method for performing such experiments was already established (Lécuyer et al., 2017). The results of this work will help to inform modelling which will extrapolate the data down to lunar-relevant conditions. [ABSTRACT FROM AUTHOR]

Dimensionless analysis was used to develop a correlative dimensionless solubility (DS) model and a predictive dimensionless solubility (pDS) model for estimating solid solubilities in supercritical carbon dioxide. Solubilities of 20 organic compounds made up of 685 data were used in developing the DS model and an additional 10 organic compounds were used for assessing the pDS model. Average relative deviation (ARD) in logarithmic solubility for literature model correlations were: Jouyban (2.06%), Hozhabr (2.09%), Jafarinejad (2.27%), Chrastil (2.49%), and Mendez-Santiago-Teja (3.46%). The proposed DS model had an ARD of 2.35% and the pDS model had an ARD of 10.5%. When the pDS model was optimized to the entire database, an ARD of 10.3% was obtained. The pDS model requires only pure solute properties (melting point, molar volume, entropy-based solubility parameter) and pure CO2 density for predicting solubility of solids in supercritical CO2 [ABSTRACT FROM AUTHOR]

This manuscript shows how computational models, mainly based on Computational Fluid Dynamics (CFD), can be used to simulate different parts of an industrial freeze-drying equipment and to properly design them; in particular, the freeze-dryer chamber and the duct connecting the chamber with the condenser, with the valves and vanes eventually present are analysed in this work. In Part 1, it will be shown how CFD can be employed to improve specific designs, to perform geometry optimization, to evaluate different design choices and how it is useful to evaluate the effect on product drying and batch variance. Such an approach allows an in-depth process understanding and assessment of the critical aspects of lyophilisation. This can be done by running either steady-state or transient simulations with imposed sublimation rates or with multi-scale approaches. This methodology will be demonstrated on freeze-drying equipment of different sizes, investigating the influence of the equipment geometry and shelf inter-distance. The effect of valve type (butterfly and mushroom) and shape on duct conductance and critical flow conditions will be instead investigated in Part 2. [ABSTRACT FROM AUTHOR]

Rosetta has detected water ice existing on the surface of Comet 67P/Churyumov-Gerasimenko in various types of features. One of particular interest is the frost-like layer observed at the edge of receding shadows during the whole mission, interpreted as the recondensation of a thin layer of water ice. Two possible mechanisms, (1) subsurface ice sublimation and (2) gas coma deposition, have been proposed for producing this recondensation process and diurnal cycles of water ice. Previous studies have demonstrated both mechanisms based on simplified models. More precise and modern models are yet insufficient when addressing the gas-coma-deposition mechanism. We aim to study the recondensation from the inner water gas coma of the 67P/Churyumov-Gerasimenko with more physical constraints including the OSIRIS images, nucleus shape model, and insolation conditions. We compute, for the first time, the backflux distributions from the coma with various boundary conditions. Numerical simulations of this gas-coma-deposition process show that the equivalent water ice deposition can be up to several microns in an hour of accumulation time close to the perihelion passage, which is comparable with the simulation results of the other subsurface-ice sublimation mechanism. [ABSTRACT FROM AUTHOR]

A prominent green emitting anhydrous (Znq 2 ) 4 tetramer phosphor has been produced by the sublimation in Ar–atmosphere from dihydrated Znq 2 . The dihydrated Znq 2 was synthesized by the co–precipitation method under normal atmospheric condition. Structural changes which are responsible for change in their photo–physical properties have been confirmed by the XRD, FTIR, NMR analysis and relative stability by the TGA/DTA analysis. The dependence of UV–visible absorption spectrum, in different acidic and basic mediums at different concentrations on the alteration of phase from dihydrated Znq 2 to anhydrous (Znq 2 ) 4 tetramer leading to the change in the band gap, has been noted. A photoluminescence spectrum of solid and of solution state and structural dependence on emission and excitation wavelength, revealing the modification in the structure, is responsible for a prominent green emission. Solvato–chromatic effect on PL emission leading to blue shift by the addition of acidic solvents and a red shift by basic solvents has also been reported. The structural formation and experimental band gap energy information has been supported by the quantum chemical calculations using DFT Computational study. We conclude from the study that the produced anhydrous (Znq 2 ) 4 tetramer phosphor has a potential application as a prominent green dopant in OLEDs including indoor lighting. Additionally, this study gives an insight into the spectroscopy of Zinc (II) quinolate complex. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO) is commonly known as a coating technique. However, the present study shows that PEO of pure Al in 10 g l −1 Na 2 WO 4 ·2H 2 O leads to the synthesis of micro and nano sized powders of WO 3 . The as-synthesized WO 3 powders have been characterized by SEM, TEM and photocatalytic tests. The plasma discharges during the PEO process have been investigated by real-time imaging and spectrographic method. The energetic features of the single discharge at different stages of PEO have been evaluated. It was suggested that the electrolyte species were directly decomposed into tungsten oxides within the discharge channels and then the oxides re-entered the electrolyte due to the lower melting and boiling points of WO 3 , and more importantly, its tendency of sublimation. [ABSTRACT FROM AUTHOR]

High quality polycrystalline CdZnTe (CZT) films were prepared on GaN substrates via close-spaced sublimation (CSS). Au electrodes were deposited on the surface of CZT films to form CZT/Au structure. XRD, SEM, EDAX and UV-Vis spectra were adopted to investigate the structure, composition and morphology of CZT films. XPS and I-V characterizations were used to investigate the surface defects and electrical properties of CZT films. The quantity of the surface defects is decreased with the extended growth times and remains stable when the deposition times exceed 20 min. The minimum resistivity of CZT thick films grown on GaN substrates is 1.12 × 10 9  Ω-cm, which is about two orders of magnitude higher than that on FTOs. The high resistivity can significantly reduce the leakage currents of CZT films and thus improve the signal-to-noise ratio of the radiation detector based on CZT films. [ABSTRACT FROM AUTHOR]

Thin 33 S samples for the study of the 33 S(n, α ) 30 Si cross-section at the n_TOF facility at CERN were made by thermal evaporation of 33 S powder onto a dedicated substrate made of kapton covered with thin layers of copper, chromium and titanium. This method has provided for the first time bare sulfur samples a few centimeters in diameter. The samples have shown an excellent adherence with no mass loss after few years and no sublimation in vacuum at room temperature. The determination of the mass thickness of 33 S has been performed by means of Rutherford backscattering spectrometry. The samples have been successfully tested under neutron irradiation. [ABSTRACT FROM AUTHOR]

In a turbine passage, the wake, which affects the heat transfer of a turbine blade, occurs periodically due to rotation of the blade. We analyzed the effect of wake on the endwall of the turbine blade according to the relative position of the turbine blade and the vane in a stationary condition. The naphthalene sublimation method was used to measure the heat transfer and detached eddy simulation (DES) was used to analyze flow characteristics. The wake from the vane was simulated by using a cylindrical rod upstream of the blade. The cylindrical rod was placed in four which positions that were aligned leading edge-to‑leading edge. The pressure and Q criterion distributions varied according to the position of the upstream wake. As the position of the upstream wake changed, the point at which the passage vortex and wake met varied. Wake and passage vortex met at x / C x  = 0.2 in position 1 and at x / C x  = 0.55 in position 2. After the wake and passage vortex had met, the secondary flow scattered. Therefore, the local and averaged heat transfer varied due to flow characteristics. Thus designers of film cooling holes on endwalls should consider these effects to ensure appropriate cooling performance. [ABSTRACT FROM AUTHOR]

CdS:Dy polycrystalline films were deposited by close-spaced vacuum sublimation (CSVS) method using glass slides as substrates. The films are highly dispersed with the grain size from smaller than 0.1 μm to 1.0 μm. The CdS:Dy films are n-type and only correspond to single wurtzite phase. The crystallites are preferentially oriented with (002) planes parallel to the substrate surface. Analysis of PL spectra, caused by the emission of donor-acceptor pairs lets us determine the nature and energy structure of the intrinsic defects and residual impurities in the films. It is important to note that the PL and reflection spectra observe the narrow lines of bound and free excitons. This allows us to found bandgaps of these films quite accurately. A correlation between optical and structural properties was established. The results of the structural and PL measurements showed that the CdS:Dy polycrystalline films are of highly crystal and optical quality. [ABSTRACT FROM AUTHOR]

Biological sulfur reduction can theoretically produce sufficient sulfide to effectively remove and recover heavy metals in the treatment of organics-deficient sulfate-rich metal-laden wastewater such as acid mine drainage and metallurgic wastewater, using 75% less organics than biological sulfate reduction. However, it is still unknown whether sulfur reduction can indeed compete with sulfate reduction, particularly under high-strength sulfate conditions. The aim of this study was to investigate the long-term feasibility of biological sulfur reduction under high sulfate conditions in a lab-scale sulfur-reducing biological sulfide production (BSP) system with sublimed sulfur added. In the 169-day trial, an average sulfide production rate (SPR) as high as 47 ± 9 mg S/L-h was achieved in the absence of sulfate, and the average SPR under sulfate-rich conditions was similar (53 ± 10 mg S/L-h) when 1300 mg S/L sulfate were fed with the influent. Interestingly, sulfate was barely reduced even at such a high strength and contributed to only 1.5% of total sulfide production. Desulfomicrobium was identified as the predominant sulfidogenic bacterium in the bioreactor. Batch tests further revealed that this sulfidogenic bacteria used elemental sulfur as the electron acceptor instead of the highly bioavailable sulfate, during which polysulfide acted as an intermediate, leading to an even higher bioavailability of sulfur than sulfate. The pathway of sulfur to sulfide conversion via polysulfide in the presence of both sulfur and sulfate was discussed. Collectively, when conditions favor polysulfide formation, sulfur reduction can be a promising and attractive technology to realize a high-rate and low-cost BSP process for treating sulfate-rich metal-laden wastewater. [ABSTRACT FROM AUTHOR]