731,155 research outputs found
Determination of the thermal stability of perfluoroalkylethers
The thermal decomposition temperatures of several commercial and custom synthesized perfluoroalkylether fluids were determined with a computerized tensimeter. In general, the decomposition temperatures of the commercial fluids were all similar and significantly higher than those for custom synthesized fluids. Correlation of the decomposition temperatures with the molecular structures of the primary components of the commercial fluids revealed that the stability of the fluids is not affected by intrinsic factors such as carbon chain length, branching, or cumulated difluoroformal groups. Instead, correlation with extrinsic factors revealed that the stability may be limited by the presence of small quantities of thermally unstable material and/or chlorine-containing material arising from the use of chlorine-containing solvents during synthesis. Finally, correlation of decomposition temperatures with molecular weights for Demnum and Krytox fluids supports a chain cleavage reaction mechanism for Demnum fluids and an unzipping reaction mechanism for Krytox fluids
R fluids
A theory of collisionless fluids is developed in a unified picture, where
nonrotating figures with anisotropic random velocity component distributions
and rotating figures with isotropic random velocity component distributions,
make adjoints configurations to the same system. R fluids are defined and mean
and rms angular velocities and mean and rms tangential velocity components are
expressed, by weighting on the moment of inertia and the mass, respectively.
The definition of figure rotation is extended to R fluids. The generalized
tensor virial equations are formulated for R fluids and further attention is
devoted to axisymmetric configurations where, for selected coordinate axes, a
variation in figure rotation has to be counterbalanced by a variation in
anisotropy excess and vice versa. A microscopical analysis of systematic and
random motions is performed under a few general hypotheses, by reversing the
sign of tangential or axial velocity components of an assigned fraction of
particles, leaving the distribution function and other parameters unchanged
(Meza 2002). The application of the reversion process to tangential velocity
components, implies the conversion of random motion rotation kinetic energy
into systematic motion rotation kinetic energy. The application of the
reversion process to axial velocity components, implies the conversion of
random motion translation kinetic energy into systematic motion translation
kinetic energy, and the loss related to a change of reference frame is
expressed in terms of systematic (imaginary) motion rotation kinetic energy. A
procedure is sketched for deriving the spin parameter distribution (including
imaginary rotation) from a sample of observed or simulated large-scale
collisionless fluids i.e. galaxies and galaxy clusters.Comment: 29 pages, 2 figure
Criticality in strongly correlated fluids
In this brief review I will discuss criticality in strongly correlated
fluids. Unlike simple fluids, molecules of which interact through short ranged
isotropic potential, particles of strongly correlated fluids usually interact
through long ranged forces of Coulomb or dipolar form. While for simple fluids
mechanism of phase separation into liquid and gas was elucidated by van der
Waals more than a century ago, the universality class of strongly correlated
fluids, or in some cases even existence of liquid-gas phase separation remains
uncertain.Comment: Proceedings of Scaling Concepts and Complex Systems, Merida, Mexic
Microfluidic and Nanofluidic Cavities for Quantum Fluids Experiments
The union of quantum fluids research with nanoscience is rich with
opportunities for new physics. The relevant length scales in quantum fluids,
3He in particular, are comparable to those possible using microfluidic and
nanofluidic devices. In this article, we will briefly review how the physics of
quantum fluids depends strongly on confinement on the microscale and nanoscale.
Then we present devices fabricated specifically for quantum fluids research,
with cavity sizes ranging from 30 nm to 11 microns deep, and the
characterization of these devices for low temperature quantum fluids
experiments.Comment: 12 pages, 3 figures, Accepted to Journal of Low Temperature Physic
Identification of Cytotoxic Flavor Chemicals in Top-Selling Electronic Cigarette Refill Fluids.
We identified the most popular electronic cigarette (EC) refill fluids using an Internet survey and local and online sales information, quantified their flavor chemicals, and evaluated cytotoxicities of the fluids and flavor chemicals. "Berries/Fruits/Citrus" was the most popular EC refill fluid flavor category. Twenty popular EC refill fluids were purchased from local shops, and the ingredient flavor chemicals were identified and quantified by gas chromatography-mass spectrometry. Total flavor chemical concentrations ranged from 0.6 to 27.9 mg/ml, and in 95% of the fluids, total flavor concentration was greater than nicotine concentration. The 20 most popular refill fluids contained 99 quantifiable flavor chemicals; each refill fluid contained 22 to 47 flavor chemicals, most being esters. Some chemicals were found frequently, and several were present in most products. At a 1% concentration, 80% of the refill fluids were cytotoxic in the MTT assay. Six pure standards of the flavor chemicals found at the highest concentrations in the two most cytotoxic refill fluids were effective in the MTT assay, and ethyl maltol, which was in over 50% of the products, was the most cytotoxic. These data show that the cytotoxicity of some popular refill fluids can be attributed to their high concentrations of flavor chemicals
Bose Fluids Above Tc: Incompressible Vortex Fluids and "Supersolidity"
This paper emphasizes that non-linear rotational or diamagnetic
susceptibility is characteristic of Bose fluids above their superfluid Tcs, and
for sufficiently slow rotation or weak B-fields amounts to an incompressible
response to vorticity. The cause is a missing term in the conventionally
accepted model Hamiltonian for quantized vortices in the Bose fluid. The
resulting susceptibility can account for recent observations of Chan et al on
solid He, and Ong et al on cuprate superconductors
Of pools, oceans, and the Dead Sea.
In a comprehensive study in this issue of Blood, Carden and colleagues describe the importance of the tonicity of IV fluids used in the treatment of patients with sickle cell disease (SCD) during vaso-occlusive crises (VOCs). Hypertonic fluids decreased sickle red blood cell (sRBC) deformability, increased occlusion, and increased sRBC adhesion in microfluidic human microvasculature models. Hypotonic fluids decreased sRBC adhesion but prolonged sRBC transit time. Fluids with intermediate tonicities resulted in optimal changes that reduced the risk of vaso-occlusion. © 2017 by The American Society of Hematology
Turbulence and structure formation in complex plasmas and fluids
The formation and evolution of nonlinear and turbulent dynamical structures
in two-dimensional complex plasmas and fluids is explored by means of
generalised (drift) fluid simulations. Recent numerical results on turbulence
in dusty magnetised plasmas, strongly coupled fluids, semi-classical
("quantum") plasmas and in rotating quantum fluids are reviewed and discussed
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The Effect of Inkjet Ink Composition on Rheology And Jetting Behaviour
This work presents recent results on the way linear and non linear viscoelastic properties of the fluids affect the jetting
mechanism. Recent progress on quantitative characterising both high frequency linear (LVE) and non-linear (NLVE) viscoelasticity
of fluids allows fluids to be assessed for their jettability before using such materials in a DoD print head. In term of linear viscoelastic measurements, the Piezo Axial Vibrator (PAV) was used to probe the rheology of the fluids on a frequency range
between 10Hz and 10000Hz. A filament stretching apparatus, called the “Cambridge Trimaster”, was used in combination with
high speed cinematography, to characterize the fluids high speed stretching and break-up behaviour. The series of fluids investigated here consist in dilutions of mono disperse polystyrene with different molecular weight (110, 210, 306 and 488 kg/mol respectively) diluted in diethyl phthalate. The choice of polymer weights and concentrations were chosen to match both the
complex viscosity and the LVE. However, non linear rheological data experiments exhibit differences in the fluid relaxation time
and filament break-up mechanism. Ultra-high speed cinematography of DoD jetting events were correlated with filament break-up experiments and demonstrated that fluid rheology provides valuable information on the jetting quality of the fluids
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