36,155 research outputs found
Enhanced toluene removal using granular activated carbon and a yeast strain candida tropicalis in bubble-column bioreactors
The yeast strain Candida tropicalis was used for the biodegradation of gaseous toluene. Toluene was effectively treated by a liquid culture of C. tropicalis in abubble-column bioreactor, and the tolueneremoval efficiency increased with decreasing gas flow rate. However, toluene mass transfer from the gas-to-liquid phase was a major limitation for the uptake of toluene by C. tropicalis. The tolueneremoval efficiency was enhanced when granularactivatedcarbon (GAC) was added as a fluidized material. The GAC fluidized bioreactor demonstrated tolueneremoval efficiencies ranging from 50 to 82% when the inlet toluene loading was varied between 13.1 and 26.9 g/m3/h. The yield value of C. tropicalis ranged from 0.11 to 0.21 g-biomass/g-toluene, which was substantially lower than yield values for bacteria reported in the literature. The maximum elimination capacity determined in the GAC fluidized bioreactor was 172 g/m3/h at atoluene loading of 291 g/m3/h. Transient loading experiments revealed that approximately 50% of the toluene introduced was initially adsorbed onto the GAC during an increased loading period, and then slowly desorbed and became available to the yeast culture. Hence, the fluidized GAC mediated in improving the gas-to-liquid mass transfer of toluene, resulting in a high tolueneremoval capacity. Consequently, the GAC bubble-column bioreactor using the culture of C. tropicalis can be successfully applied for the removal of gaseous toluene
Mediatization of Emotion on Social Media: Forms and Norms in Digital Mourning Practices
This article provides the theoretical background for this Special Issue which explores the mediatization of emotion on social media as attested in different digital mourning practices. The overview discusses the affective and emotional turn alongside the mediatic turn in relation to key trends and foci in the study of affect/emotion. Our discussion points to a shift in conceptualizations of affect/emotion from mediated to mediatized practice, embedded in other social practices and subject to media and social media logics, affordances, and frames, which are worthy of empirical investigation. The article also presents key insights offered in the four articles of this Special Issue and foregrounds current and future directions in the study of mediatization, emotional sharing, and digital mourning practices
Shear flow of angular grains: acoustic effects and non-monotonic rate dependence of volume
Naturally-occurring granular materials often consist of angular particles
whose shape and frictional characteristics may have important implications on
macroscopic flow rheology. In this paper, we provide a theoretical account for
the peculiar phenomenon of auto-acoustic compaction -- non-monotonic variation
of shear band volume with shear rate in angular particles -- recently observed
in experiments. Our approach is based on the notion that the volume of a
granular material is determined by an effective-disorder temperature known as
the compactivity. Noise sources in a driven granular material couple its
various degrees of freedom and the environment, causing the flow of entropy
between them. The grain-scale dynamics is described by the
shear-transformation-zone (STZ) theory of granular flow, which accounts for
irreversible plastic deformation in terms of localized flow defects whose
density is governed by the state of configurational disorder. To model the
effects of grain shape and frictional characteristics, we propose an Ising-like
internal variable to account for nearest-neighbor grain interlocking and
geometric frustration, and interpret the effect of friction as an acoustic
noise strength. We show quantitative agreement between experimental
measurements and theoretical predictions, and propose additional experiments
that provide stringent tests on the new theoretical elements.Comment: 12 pages, 3 figure
Stick-slip instabilities in sheared granular flow: the role of friction and acoustic vibrations
We propose a theory of shear flow in dense granular materials. A key
ingredient of the theory is an effective temperature that determines how the
material responds to external driving forces such as shear stresses and
vibrations. We show that, within our model, friction between grains produces
stick-slip behavior at intermediate shear rates, even if the material is
rate-strengthening at larger rates. In addition, externally generated acoustic
vibrations alter the stick-slip amplitude, or suppress stick-slip altogether,
depending on the pressure and shear rate. We construct a phase diagram that
indicates the parameter regimes for which stick-slip occurs in the presence and
absence of acoustic vibrations of a fixed amplitude and frequency. These
results connect the microscopic physics to macroscopic dynamics, and thus
produce useful information about a variety of granular phenomena including
rupture and slip along earthquake faults, the remote triggering of
instabilities, and the control of friction in material processing.Comment: 12 pages, 8 figure
Study of timing performance of Silicon Photomultiplier and application for a Cherenkov detector
Silicon photomultipliers are very versatile photo detectors due to their high
photon detection efficiency, fast response, single photon counting capability,
high amplification, and their insensitivity to magnetic fields. At our
institute we are studying the performance of these photo detectors at various
operating conditions. On the basis of the experience in the laboratory we built
a prototype of a timing Cherenkov detector consisting of a quartz radiator with
two mm MPPCs S10362-33-100C from Hamamatsu Photonics as
photodetectors. The MPPC sensors were operated with Peltier cooling to minimize
thermal noise and to avoid gain drifts. The test measurements at the DANE
Beam-Test Facility (BTF) at the Laboratori Nazionali di Frascati (LNF) with
pulsed 490 MeV electrons and the results on timing performance with Cherenkov
photons are presented.Comment: Conference proceedings of 12th Vienna Conference on Instrumentation
201
Coating thickness and coverage effects on the forces between silica nanoparticles in water
The structure and interactions of coated silica nanoparticles have been
studied in water using molecular dynamics simulations. For 5 nm diameter
amorphous silica nanoparticles we studied the effects of varying the chain
length and grafting density of polyethylene oxide (PEO) on the nanoparticle
coating's shape and on nanoparticle-nanoparticle effective forces. For short
ligands of length and repeat units, the coatings are radially
symmetric while for longer chains () the coatings are highly
anisotropic. This anisotropy appears to be governed primarily by chain length,
with coverage playing a secondary role. For the largest chain lengths
considered, the strongly anisotropic shape makes fitting to a simple radial
force model impossible. For shorter ligands, where the coatings are isotropic,
we found that the force between pairs of nanoparticles is purely repulsive and
can be fit to the form where is the separation
between the center of the nanoparticles, is the radius of the
silica core, and is measured to be between 2.3 and 4.1.Comment: 20 pages, 6 figure
Türkiye's Foreign Trade Applications
Import and export customs rules and regulations are generally standardized and comparable in the majority of nations worldwide. This tendency is associated with the 1947 foundation of the GATT and the later development of the WTO, which has pushed to liberalize and ease international commerce. These initiatives have led to the expansion and integration of the global economy. This study aims to investigate the evolution of Türkiye's foreign trade policy through time and how the country has reacted to shifting global economic circumstances. The research will investigate the export and import agreements, product suggestions, and regulatory rules that have evolved through time to ease international commerce. Particular attention will be paid to the developments in Türkiye's trade policy from the 1970s to the current years when Türkiye started liberalizing its trade policy and adopting a more open and balanced approach. The research will also analyze Türkiye's attempts to diversify its trade partners and boost its competitiveness in international markets, as well as its efforts to align its laws and regulations with those of other nations. This study will examine how these initiatives have contributed to the economic growth and development of Türkiye throughout time
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