Search results for "medium"
showing 10 items of 3746 documents
Effect of different sintering process on flexural strength of translucency monolithic zirconia
2018
Background Sintering process is responsible for the strength of zirconia restoration. This study evaluated the effect of different sintering temperatures and sintered-holding times on flexural strength of translucency 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, …
Influence of artificial aging and ZrO2 nanoparticle-reinforced repair resin on the denture repair strength
2019
Background The purpose of this study was to evaluate the effect of aging process on the tensile strength (TS) of repaired acrylic denture base using ZrO2 nanoparticles (nano-ZrO2)-reinforced autopolymerized resin. Material and Methods A total of 240 heat-polymerized acrylic resin specimens (n=10) were prepared and sectioned creating 2 mm-repair-gap. Autopolymerized acrylic resin, pure and modified with 2.5, 5, and 7.5wt% nano-ZrO2 were used for specimens repair. TS of repaired specimens were measured using the universal testing machine after water immersion at 37oC for 2, 7 and 30 days. At each time interval, half the immersed specimens underwent thermo-cycling aging process (5000 cycles at…
Convective Roll Instabilities of Vertical Throughflow with Viscous Dissipation in a Horizontal Porous Layer
2009
Published version of an article from the journal: Transport in Porous Media. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11242-009-9417-y The vertical throughflow with viscous dissipation in a horizontal porous layer is studied. The horizontal plane boundaries are assumed to be isothermal with unequal temperatures and bottom heating. A basic stationary solution of the governing equations with a uniform vertical velocity field (throughflow) is determined. The temperature field in the basic solution depends only on the vertical coordinate. Departures from the linear heat conduction profile are displayed by the temperature distribution due to the forced con…
Linear instability of mixed convection of cold water in a porous layer induced by viscous dissipation
2009
Accepted version of an article published in the journal: International Journal of Thermal Sciences, Elsevier Published version available on Science Direct: http://dx.doi.org/10.1016/j.ijthermalsci.2008.06.012 An analysis of linear stability of the stationary laminar Darcy flow in a horizontal porous layer is performed. The porous layer is saturated with cold water. The upper plane boundary is assumed to be subject to heat transfer with finite conductance to an environment at the temperature of maximum density of cold water. The lower plane boundary is adiabatic. Convective instabilities are caused by flow viscous dissipation, inducing a basic temperature distribution that decreases in the u…
Nanofilm metal layers as vacuum quality sensors
2010
Abstract A monitoring device for vacuum quality is realized by lowest cost single use oxygen sensors for vacuum insulation panels. They use the pressure dependence of oxide layer growth thickness on electrically measured metal nanofilms. These films were manufactured by e-beam evaporation, characterized in terms of resistance change with subsequent modeling of underlying mechanisms.
Valdības loma mazo un vidējo uzņēmumu attīstībā Baltijas valstīs
2019
Mazajiem un vidējiem uzņēmumiem ir nozīmīga loma valstu attīstībā visā pasaulē. Uzņēmumu konkurētspēja ir liela daļa no visas valsts konkurētspējas. Tāpēc īpaša uzmanība jāpievērš mazo un vidējo uzņēmumu attīstībai. Darba mērķis ir novērtēt dažādu atbalsta pasākumu ietekmi uz mazo un vidējo uzņēmumu attīstību un sniegumu, lai risinātu problēmars, kas kavē to veiksmīgu attīstību. Pētījuma teorētiskā daļa ietver dažādu autoru veiktos MVU raksturojumus, kā arī iespējamos atbalsta pasākumus. Lai risinātu šo tēmu, tika izmantota kvalitatīvo pētījuma metode. Tika aptaujāti eksperti uzņēmējdarbības jomā, pēc tam tos analizēja autors. Pētījuma secinājumi noder politikas veidotājiem, komercbankām un…
Mazu un vidēju uzbekistānas uzņēmumu eksports: Lauksaimniecības produktu pārbaude
2020
Neskatoties uz pastāvīgu Uzbekistānas Republikas eksporta kvantitatīvo un kvalitatīvo rādītāju pieaugumu un ārējās tirdzniecības liberalizāciju, eksporta aktivitāte parāda vairākus faktorus, kuriem ir būtiska ierobežojoša ietekme uz MVU republikas eksporta attīstību. Tāpēc šis pētījums tika veikts ar mērķi izcelt un novērot izaicinājumus un nākotnes izredzes, ar kurām saskaras MVU, Uzbekistānas lauksaimniecības un pārtikas eksporta pierādījumos. Pieejas pamatā ir MVU eksporta novērošana, galvenokārt lauksaimniecības un pārtikas eksporta vide, tiešsaistes un papīra recenzijas akadēmiskajos žurnālos, grāmatās un iepriekšējos pētījumos. Pētījumā izmantota kvalitatīvā metode, un dati tiek apkop…
Localisation vs. delocalisation in the dimeric mixed-valence clusters in the generalised vibronic model. Magnetic manifestations
1999
Abstract The problem of localisation–delocalisation in the dimeric mixed-valence clusters is considered in the framework of the generalised vibronic model. The model takes into account both the local vibrations on the metal sites (Piepho–Krausz–Schatz model) and the multicenter (molecular) vibrations changing the intermetallic distances (as suggested by Piepho). In the framework of the semiclassical adiabatic approach the potential surfaces are analysed and different kinds of localised and delocalised states are found. On the basis of the calculated degrees of the localisation the conventional Robin and Day classification of mixed-valence compounds is reconsidered in view of the generalised…
Structural diversity in charge transfer salts based on Mo3S7 and Mo3S4Se3 clusters complexes and bis(ethylenedithio)tetrathiafulvalene (ET)
2007
Chemical modification of the trinuclear [Mo3(μ3-S)(μ2-S2)3Br6]2− cluster, at either the outer bromine or the disulfide ligands, allows the facile preparation of the dianions [Mo3(μ3-S)(μ2-S2)3(tdas)3]2− ([1]2−) (tdas = 1,2,5-thiadiazole-3,4-dithiol), [Mo3(μ3-S)(μ2-SSe)3Br6]2− ([2]2−) and [Mo3(μ3-S)(μ2-S2)3Cl6]2− ([3]2−). Electrocrystallization of bis(ethylenedithio)tetrathiafulvalene (ET) in the presence of these dianions affords a series of charge transfer salts, namely (ETA)(ETB)[1], (ETA)(n-Bu4N)[2], (ETA)(ETB)[3]2·CH3CN, and ((ETA)(ETB)(ETC)(ETD))2{[3]2Cl}·CH3CN, where the ET subscripts denote crystallographically independent molecules. In all cases, the various cluster–cluster, cluster…
Disentangling human from natural factors: Taphonomical value of microanatomical features on archaeological wood and charcoal assemblages
2020
International audience; Archaeobotanical charcoal and wood analyses rely on the observation of different macro and microanatomical features affecting wood structure to variable extents. These features may result from a wide range of intrinsic and extrinsic factors alluding to different stages of the wood's taphonomical history: initial growth conditions, human selection, transformation/use and discard, post-depositional processes and archaeological sampling strategies. Papers in this volume address taphonomy in this broad sense, through recent methodological work mainly based on experimentation and case studies from a variety of chrono-cultural and geographical contexts. The authors present…