219 research outputs found
Stringiness of Hyaluronic Acid Emulsions
In this work, we underline the importance of the molecular weight of
hyaluronic acid on the elongational properties of concentrated emulsions. The
filament formation properties, e.g. the stringiness, of an emulsion is a key
determinant of a product liking and repeat purchase. Here, we find that high
molecular weight hyaluronic acid and a high stretching speed are the control
parameters affecting the filament formation of an emulsion.Comment: 15 pages, 4 figures. Published in International Journal of Cosmetic
Science, 202
Numerical simulations of mass outflows driven from accretion disks by radiation and magnetic forces
We study the two-dimensional, time-dependent MHD of radiation-driven winds
from luminous accretion disks initially threaded by a purely axial magnetic
field. The radiation force is mediated primarily by spectral lines. We use
ideal MHD to compute the evolution of Keplerian disks, varying the magnetic
field strengths and the luminosity of the disk, the central accreting object or
both. We find that the magnetic fields very quickly start deviating from purely
axial due to the magnetorotational instability. This leads to fast growth of
the toroidal magnetic field. As a result the toroidal field dominates over the
poloidal field above the disk and the gradient of the former drives a slow and
dense disk outflow, which conserves specific angular momentum. Depending on the
strength of the magnetic field relative to the system luminosity the disk wind
can be radiation- or MHD driven. The pure radiation-driven wind consists of a
dense, slow outflow that is bounded on the polar side by a high-velocity
stream. The mass-loss rate is mostly due to the fast stream. As the magnetic
field strength increases first the slow part of the flow is affected, namely it
becomes denser and slightly faster and begins to dominate the mass-loss rate.
In very strong magnetic field or pure MHD cases, the wind consists of only a
dense, slow outflow without the presence of the distinctive fast stream so
typical to pure radiation-driven winds. Our simulations indicate that winds
launched by the magnetic fields are likely to remain dominated by the fields
downstream because of their relatively high densities.Comment: 30 pages, 4 figure (fig. 1 and fig. 2 in color), to appear in ApJ,
"see also http://rocinante.colorado.edu/~proga/
Формирование приоритетов интенсификации факторов производства угольного предприятия на основе структурно-иерархического анализа
Проведено оцінку взаємного впливу чинників виробництва і пріоритетів їх формування на базі підприємств вугільної галузі на основі структурно-ієрархічного підходу. Обґрунтовано можливості йі умови аналізу багатоваріантності впливів чинників праці і капіталу на зниження трудомісткості і капіталомісткості очисних робіт. Доведено доцільність застосування методу аналізу ієрархій, за допомогою якого побудовано матриці парних порівнянь.
Ключові слова: інтенсифікація чинників виробництва, матриця попарних порівнянь, метод аналізу ієрархій, структурно-ієрархічний метод, чинники виробництва.Проведена оценка взаимного влияния факторов производства и приоритетов их формирования на базе предприятий угольной отрасли на основе структурно-иерархического подхода. Обоснованы возможности и условия анализа многовариантности воздействия факторов труда и капитала на снижение трудоемкости и капиталоемкости очистных работ. Доказана целесообразность применения метода анализа иерархий, с помощью которого построены матрицы парных сравнений.
Ключевые слова: интенсификация факторов производства, матрица попарных сравнений, метод анализа иерархий, структурно-иерархический метод, факторы производства.In new economics which is based on the knowledge system the level and complicity of innovation development of industrial complexenterprise is determined by such deep transformational phenomena as change of structure of technological modes in world economy, change of qualitative and quantitative proportions of production factors and, in particular, intensification of production factors, which is able to solve such actual problem as migration to primary intensive way of development. That is why the purpose of this research is development and improvement of methodological approach to formation of priority variants of production factors intensification on the basis of method of hierarchies analysis. For solution ofthis task the method of hierarchies analysis is usedwhich is systematic procedure for hierarchical expressing the elements determining the essence of any problem.
The assessment of mutual influence of production factors and priorities of their formation by the example of coal industry enterprise on the basis of structural-hierarchic approach is given in the article. On the basis of structural-hierarchic approach the criteriawere formed, which, each in different ways and with different level of intensity, make influence on meaning of coal enterprise factors. There were proved the possibilities and conditions of multipart influence of labor factors and capital on decrease of labor and capital intensity of coal-face works, which will allow giving rise in increasing effectiveness while securing necessary labor safety. Practicability of method of hierarchies analysis, with the help of which the comparison-of-pairs matrix were built, was proved. Investigation conducted allowed choosing the directions of capital investments for the purpose of getting maximum effect.
Keywords: production factors intensification, comparison-of-pairs matrix, method of hierarchies analysis, structural-hierarchic method, production factors
Interacting Growth Walk - a model for hyperquenched homopolymer glass?
We show that the compact self avoiding walk configurations, kinetically
generated by the recently introduced Interacting Growth Walk (IGW) model, can
be considered as members of a canonical ensemble if they are assigned random
values of energy. Such a mapping is necessary for studying the thermodynamic
behaviour of this system. We have presented the specific heat data for the IGW,
obtained from extensive simulations on a square lattice; we observe a broad
hump in the specific heat above the -point, contrary to expectation.Comment: 4 figures; Submitted to PR
Photonic crystals of coated metallic spheres
It is shown that simple face-centered-cubic (fcc) structures of both metallic
and coated metallic spheres are ideal candidates to achieve a tunable complete
photonic bandgap (CPBG) for optical wavelengths using currently available
experimental techniques. For coated microspheres with the coating width to
plasma wavelength ratio and the coating and host
refractive indices and , respectively, between 1 and 1.47, one can
always find a sphere radius such that the relative gap width (gap
width to the midgap frequency ratio) is larger than 5% and, in some cases,
can exceed 9%. Using different coatings and supporting liquids, the width
and midgap frequency of a CPBG can be tuned considerably.Comment: 14 pages, plain latex, 3 ps figures, to appear in Europhys. Lett. For
more info on this subject see
http://www.amolf.nl/research/photonic_materials_theory/moroz/moroz.htm
Ethyl cellulose nanoparticles as stabilizers for Pickering emulsions
Pickering emulsions stabilized by ethyl cellulose nanoparticles have recently received –great attention for their remarkable stability and numerous industrial applications. De- spite this, the exact stabilization mechanism of such Pickering emulsions is still not fully understood. Both the stabilization of the emulsion by particle adsorption at the inter- face and through network formation in the continuous phase (leading to a yield stress) have been suggested. In this work we study soybean oil-in-water emulsions stabilized by ethyl cellulose nanoparticles and find, by the use of confocal microscopy and interfa- cial tension measurements, that the main stabilization mechanism of this nanoparticle- stabilized emulsions is the adsorption of the particles at the interface, instead of forming a network in the continuous phase. At the same time, oscillatory rheology measurements reveal that the emulsions exhibit a yield stress well below the random close-packing limit for hard spheres, suggesting short-range interactions between the droplets caused by the presence of the particles at the interface. The presence of the particles at the interface in combination with the observed rheological behavior of an attractive emulsion gives a strong indication for a particle-bridged stabilized emulsions
Design and characterization of Ca-Fe(III) pyrophosphate salts with tunable pH-dependent solubility for dual-fortification of foods
Food-fortification using poorly water-soluble mineral-containing compounds is a common approach to deliver iron. However, it comes with the challenge of ensuring iron bio-accessibility and limiting iron-phenolic interactions that can change organoleptic properties. Mixed Ca-Fe(III) pyrophosphate salts with the general formula Ca2(1-x)Fe4x(P2O7)(1+2x) were designed as a system for simultaneous delivery of iron and calcium. The salts were synthesized via a co-precipitation method and characterized by TEM-EDX, XRD, and FT-IR. All mixed salts with 0.14 ≤ x ≤ 0.35 yielded homogenous amorphous particles. The iron dissolution from these mixed salts showed a fourfold increase at gastric pH compared to Fe(III) pyrophosphate. In the food-relevant pH range, the salts with x ≤ 0.15 showed up to an eight-fold decrease in iron solubility. Despite this, reactivity of the mixed salts in tea was similar to that of FePP. Our results indicate that these mixed salts are potential dual-fortificants with tunable iron content and solubility
Origin of the short-range, strong repulsive force between ionic surfactant layers
We study the electrostatic interaction between two ionic surfactant layers by performing molecular dynamic simulations of salt-free thin water films coated by surfactants (Newton black films). We find a strong exponentially decaying short-range repulsion not explained by classical Poisson-Boltzmann theory. This electrostatic force is shown to be mainly due to the anomalous dielectric response of water near charged surfactant layers. This result clarifies the much debated physical mechanism underlying the controversial "hydration forces" observed in experiments. In the case of ionic thin films, the "hydration forces" can be identified with the electrostatic forces induced by the layers of highly polarized water originated at the interfaces
Viscous Effects on Inertial Drop Formation
The breakup of low-viscosity droplets like water is a ubiquitous and rich phenomenon. Theory predicts that in the inviscid limit one observes a finite-time singularity, giving rise to a universal power law, with a prefactor that is universal for a given density and surface tension. This universality has been proposed as a powerful tool to determine the dynamic surface tension at short time scales. We combine high-resolution experiments and simulations to show that this universality is unobservable in practice: in contrast to previous studies, we show that fluid and system parameters do play a role; notably a small amount of viscosity is sufficient to alter the breakup dynamics significantly
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