1,704 research outputs found
Ultra-high permeable phenine nanotube membranes for water desalination
Nanopore desalination technology hinges on high water-permeable membranes
which, at the same time, block ions efficiently. In this study, we consider a
recently synthesized [Science 363, 151-155 (2019)] phenine nanotube (PNT) for
water desalination applications. Using both equilibrium and non-equilibrium
molecular dynamics simulations, we show that the PNT membrane completely
rejects salts, but permeates water at a rate which is an order-of-magnitude
higher than that of all the membranes used for water filtration. We provide the
microscopic mechanisms of salt rejection and fast water-transport by
calculating the free-energy landscapes and electrostatic potential profiles. A
collective diffusion model accurately predicts the water permeability obtained
from the simulations over a wide range of pressure gradients. We propose a
method to calculate the osmotic water permeability from the equilibrium
simulation data and find that it is very high for the PNT membrane. These
remarkable properties of PNT can be applied in various nanofluidic
applications, such as ion-selective channels, ionic transistors, sensing,
molecular sieving, and blue energy harvesting.Comment: 23 pages, 5 figure
Minimization of Handoff Failure Probability for Next-Generation Wireless Systems
During the past few years, advances in mobile communication theory have
enabled the development and deployment of different wireless technologies,
complementary to each other. Hence, their integration can realize a unified
wireless system that has the best features of the individual networks.
Next-Generation Wireless Systems (NGWS) integrate different wireless systems,
each of which is optimized for some specific services and coverage area to
provide ubiquitous communications to the mobile users. In this paper, we
propose to enhance the handoff performance of mobile IP in wireless IP networks
by reducing the false handoff probability in the NGWS handoff management
protocol. Based on the information of false handoff probability, we analyze its
effect on mobile speed and handoff signaling delay.Comment: 16 Page
Dynein catch bond as a mediator of codependent bidirectional cellular transport
Intracellular bidirectional transport of cargo on microtubule filaments is
achieved by the collective action of oppositely directed dynein and kinesin
motors. Experiments have found that in certain cases, inhibiting the activity
of one type of motor results in an overall decline in the motility of the
cellular cargo in both directions. This counter-intuitive observation, referred
to as {\em paradox of codependence} is inconsistent with the existing paradigm
of a mechanistic tug-of-war between oppositely directed motors. Unlike kinesin,
dynein motors exhibit catchbonding, wherein the unbinding rates of these motors
decrease with increasing force on them. Incorporating this catchbonding
behavior of dynein in a theoretical model, we show that the functional
divergence of the two motors species manifests itself as an internal regulatory
mechanism, and leads to codependent transport behaviour in biologically
relevant regimes. Using analytical methods and stochastic simulations, we
analyse the processivity characteristics and probability distribution of run
times and pause times of transported cellular cargoes. We show that
catchbonding can drastically alter the transport characteristics and also
provide a plausible resolution of the paradox of codependence.Comment: 14 pages, 13 figure
Continuous transition of social efficiencies in the stochastic strategy Minority Game
We show that in a variant of the Minority Game problem, the agents can reach
a state of maximum social efficiency, where the fluctuation between the two
choices is minimum, by following a simple stochastic strategy. By imagining a
social scenario where the agents can only guess about the number of excess
people in the majority, we show that as long as the guess value is sufficiently
close to the reality, the system can reach a state of full efficiency or
minimum fluctuation. A continuous transition to less efficient condition is
observed when the guess value becomes worse. Hence, people can optimize their
guess value for excess population to optimize the period of being in the
majority state. We also consider the situation where a finite fraction of
agents always decide completely randomly (random trader) as opposed to the rest
of the population that follow a certain strategy (chartist). For a single
random trader the system becomes fully efficient with majority-minority
crossover occurring every two-days interval on average. For just two random
traders, all the agents have equal gain with arbitrarily small fluctuations.Comment: 8 pages, 6 fig
Fluorinated lactide-based copolymers
Disclosed is a process for producing lactide-based copolymers and the copolymers produced by this process. Disclosed copolymers are formed in one embodiment through the copolymerization of a lactide monomer with a fluorinated diol, for example a perfluorinated polyether monomer, oligomer or copolymer. The disclosed materials may display improved mechanical characteristics, hydrolytic characteristics, and thermal characteristics as compared to previously known lactide-based materials
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