39 research outputs found
Особливості планування і реалізації проектів ресторанного бізнесу
Ресторанний бізнес є однією із найбільш значущих складових індустрії гостинності. Водночас, ресторанний бізнес, з одного боку, є одним із засобів високоліквідного використання капіталу, а з іншого − середовищем із високим ступенем конкурентності. У всьому світі він є одним із найбільш розповсюджених видів малого бізнесу, тому заклади та підприємства ведуть між собою постійну боротьбу за сегментацію ринку, за пошук нових та за утримання постійних споживачів їхньої продукції та послуг. Всі заклади та підприємства повинні мати високий рівень конкурентоспроможності та мати свою унікальність
Hierarchical Biomolecular Emulsions Using 3‑D Microfluidics with Uniform Surface Chemistry
Microfluidic
devices can be used to produce single, double and
higher order emulsions, where droplet sizes can be precisely controlled
and modulated. Such emulsions have great potential for the storage
and study of biomolecules, including peptides and proteins. However,
advancement of this technique has remained challenging due to the
tendency of various biomolecules to adhere to the surface of the formed
channels, resulting in changes in surface wetting and fouling on the
micrometer scale. Thus, precise control of surface wettability plays
a crucial role in the processes that govern droplet formation. Here,
we report an approach for producing both water–oil–water
(w/o/w) and oil–water–oil (o/w/o) double emulsions without
any need for surface modification, an enabling feature for biomolecular
encapsulation. Using this strategy, we show that the number of monodisperse
encapsulated internal droplets can be controlled systematically and
reproducibly by suitable adjustment of the relevant flow rates, and
ranges from 1 to 40 in the case of w/o/w emulsions. We further demonstrate
that the number of internal droplets scales linearly with the reciprocal
flow rate of the outer continuous phase, when the inner and middle
phase flow rates are kept constant. We demonstrate that this approach
is suitable for forming double emulsions where the inner phase consists
of reconstituted silk protein solution whereby incubation of the internal
droplets can be induced to form a gel resulting in silk fibroin microgels
surrounded by an external oil shell. Finally, for o/w/o emulsions,
we show that single or multiple monodisperse internal droplets can
be encapsulated with a size that ranges over 1 order of magnitude,
from ca. 10 μm to >100 μm. Moreover, o/w/o emulsions
where
the middle phase consists of silk fibroin solution were prepared and
by allowing the protein to aggregate, a core–shell structure
was formed. This microfluidic strategy allows for multiple emulsions
to be generated drop by drop for biomolecular solutions with potential
applications in the biomedical and pharmaceutical fields
The miscibility limit, <i>βϵ</i>*, of a chaperone–client mixture depends on the chaperone–client binding strength, <i>βϵ</i><sub>c-s</sub>, and the chaperone stoichiometric fraction, <i>x</i><sub>c</sub>.
<p>The chaperone–chaperone interactions have only a minor effect on <i>βϵ</i>*: the miscibility limits of solutions with promiscuous chaperone interfaces, for which <i>βϵ</i><sub>c-c</sub> = <i>βϵ</i><sub>c-s</sub>, are indicated by open circles, while the miscibility limits of solutions in which chaperone–chaperone interactions are prevented are indicated by closed circles. The client–client interaction strength, <i>βϵ</i><sub>s-s</sub>, is sufficient to drive the aggregation of clients in the absence of chaperones.</p
The optimized design window for a passive molecular chaperone coincides with the conditions under which chaperone oligomerization is most probable.
<p>(a) The response in the solution miscibility limit to an increase in the chaperone stoichiometric fraction. The approximately linear response regime for strong binding chaperones is indicated in red. (b) The response in the solution miscibility limit to an increase in the chaperone–client binding strength. (c) The probability that a chaperone binding interface is bound to another chaperone monomer. For a given stoichiometric ratio of chaperones and clients, this probability is greatest in approximately the same design window in which both ∂<i>βϵ</i>*/∂<i>x</i><sub>c</sub> and ∂<i>βϵ</i>*/∂<i>βϵ</i><sub>c-s</sub> are simultaneously maximized.</p
A minimal model of an associating fluid of passive chaperones and aggregation-prone client proteins.
<p>Chaperone and client monomers interact via nearest-neighbor interactions on a three-dimensional cubic lattice. Orientationally averaged nonspecific interactions may be either attractive or repulsive. Directional interactions between specific binding sites, indicated by blue patches, depend on the relative orientations of the monomers and are always attractive.</p
Density-Gradient-Free Microfluidic Centrifugation for Analytical and Preparative Separation of Nanoparticles
Sedimentation
and centrifugation techniques are widely applied
for the separation of biomolecules and colloids but require the presence
of controlled density gradients for stable operation. Here we present
an approach for separating nanoparticles in free solution without
gradients. We use microfluidics to generate a convective flow perpendicular
to the sedimentation direction. We show that the hydrodynamic Rayleigh–Taylor-like
instability, which, in traditional methods, requires the presence
of a density gradient, can be suppressed by the Poiseuille flow in
the microchannel. We illustrate the power of this approach by demonstrating
the separation of mixtures of particles on the nanometer scale, orders
of magnitude smaller than the micrometer-sized objects separated by
conventional inertial microfluidic approaches. This technique exhibits
a series of favorable features including short analysis time, small
sample volume, limited dilution of the analyte, limited interactions
with surfaces as well as the possibility to tune easily the separation
range by adjusting the geometry of the system. These features highlight
the potential of gradient-free microfluidic centrifugation as an attractive
route toward a broad range of nanoscale applications
The rigidity of the fibers can be reduced by removing the chirality of the employed model.
<p>In such systems, the fibers can bend to form a ring (depicted as a simulation snapshot in part B), which does not have a loose end available for further growth. This effects the whole growth process (shown in part A as a relative fiber mass concentration depending on time) and it results in a deviation from a global fit to Oosawa's theory, especially at later stages of the fibrillar growth, since there is no such effect included in theory. The fitted values are = 4.0 and . The black curve represents simulation data and the red curve is the fit.</p
The fibril growth from our simulation and corresponding fit by Oosawa's theory.
<p>The peptide concentrations are from left to right 7.97, 2.36, 1.00, 0.51, 0.30, and 0.19 mM. The fitted size of nucleus and growth rate are 3.8 particle and respectively. The inset shows the fit to obtain the nucleus size via the halftimes according to <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1002692#pcbi.1002692.e067" target="_blank">Eq. 2</a>. The logarithmic time scale tends to visually over-emphasize the differences between the global fit (red curve) and data (black curve) at short time (highest concentrations).</p
Representative snapshot of the simulation box in the later stage of the fibril growth.
<p>The blue/red particles are in the random coil state, while the orange/grey particles are in the -sheet state. Note that the particles in the random coil state are mostly monomers in solution or at the end of the fibres, while the -sheet are forming chiral cross stacked fibrils.</p
The configurations of small oligomers in the interaction minima with marked interactions and the total enthalpic contributions.
<p>The subscript and the size of the patch denotes the internal state of the PSC mode (: random coil and : -sheet).</p