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A magnet-actuated biomimetic device for isolating biological entities in microwells
No full textMicrowell platforms show great promise in single-cell studies and protein measurements because of their low volume sampling, rapid analysis and high throughput screening ability. However, the existing actuation mechanisms to manipulate the target samples and fabrication procedures involved in the microwell-based microfluidic devices are complex, resource-intensive and require an external power source. In this work, we present proof of concept of a simple, power-free and low-cost closed magnet digital microfluidics device for isolating biological entities in femtoliter-sized microwells. The target biological entities were encapsulated in magnetic liquid marbles and shuttled back and forth between micropatterned top and bottom plates in the microdevice to obtain high loading efficiency and short processing time. The microdevice performance was studied through fluorescent detection of three different entities: microbeads, bovine serum albumin (BSA) and Escherichia coli, captured in the microwell array. Almost 80% of the microwells were loaded with single microbeads in five shuttling cycles, in less than a minute. Further, a low volume of BSA was compartmentalized in the microwell array over a two order range of concentration. The microdevice exhibits two unique features: lotus leaf stamps were used to fabricate micropatterns (microwells and micropillars) on top and bottom plates to impart functionality and cost-effectiveness, and the target samples were actuated by a permanent magnet to make the microdevice power-free and simple in operation. The developed biomimetic microdevice is therefore capable of capturing a multitude of biological entities in low-resource settings
Protecting solid-state spins from a strongly coupled environment
No full textQuantum memories are critical for solid-state quantum computing devices and a good quantum memory requires both long storage time and fast read/write operations. A promising system is the nitrogen-vacancy (NV) center in diamond, where the NV electronic spin serves as the computing qubit and a nearby nuclear spin as the memory qubit. Previous works used remote, weakly coupled C-13 nuclear spins, trading read/write speed for long storage time. Here we focus instead on the intrinsic strongly coupled N-14 nuclear spin. We first quantitatively understand its decoherence mechanism, identifying as its source the electronic spin that acts as a quantum fluctuator. We then propose a scheme to protect the quantum memory from the fluctuating noise by applying dynamical decoupling on the environment itself. We demonstrate a factor of 3 enhancement of the storage time in a proof-of-principle experiment, showing the potential for a quantum memory that combines fast operation with long coherence time
Release velocities and bowler performance in cricket
No full textThere is a widespread notion in the cricketing world that with increasing pace the performance of a bowler improves. Additionally, many cricket experts believe faster bowlers to be more effective against lower order batters than bowlers who bowl at slower speeds. The present study puts these two ubiquitous notions under test by statistically analysing the differences in performance of bowlers from three subpopulations based on average release velocities. Results from one-way ANOVA (and its modified versions), for international test matches, reveal faster bowlers to be performing better, in terms of Average and Strike-rate, but no significant differences in the Economy rate and Dynamic Bowling rate. Faster bowlers were found to be more effective in taking wickets of lower and middle order batters as compared to bowlers with less pace. However, there was no statistically significant difference in performance of Fast and Fast-Medium bowlers against a top-order batter
Squeezing Enhances Quantum Synchronization
No full textIt is desirable to observe synchronization of quantum systems in the quantum regime, defined by the low number of excitations and a highly nonclassical steady state of the self-sustained oscillator. Several existing proposals of observing synchronization in the quantum regime suffer from the fact that the noise statistics overwhelm synchronization in this regime. Here, we resolve this issue by driving a self-sustained oscillator with a squeezing Hamiltonian instead of a harmonic drive and analyze this system in the classical and quantum regime. We demonstrate that strong entrainment is possible for small values of squeezing, and in this regime, the states are nonclassical. Furthermore, we show that the quality of synchronization measured by the FWHM of the power spectrum is enhanced with squeezing
Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb-Pb collisions at root s(NN)=2.76 TeV
No full textIn ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v(2) reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two-and three-particle correlations in Pb-Pb collisions at root s(NN) = 2.76 TeV. The two-particle correlator , calculated for different combinations of charges alpha and beta, is almost independent of v(2) (for a given centrality), while the three-particle correlator scales almost linearly both with the event v(2) and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on v(2) points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10-50% centrality interval is found to be 26-33% at 95% confidence level. (c) 2017 The Author(s). Published by Elsevier B.V
The origin of diverse lattice dynamics in the graphene family
No full textWe employ first principles based density functional theory calculations to explore the lattice dynamics of members of the graphene family. We explore the changes observed in the lattice thermal conductivity via adopting physical models for estimating phonon lifetimes. This allows us to establish a connection between the parameters such as group velocity, Gruneisen parameter, and Debye temperature of the acoustic phonon modes and the lattice thermal conductivity. Our calculations show that the presence of buckling reduces the group velocity and the Debye temperature of the sheets down the group, and hence, reduces their lattice thermal conductivity. however, there is no linear dependence between the buckling height and the observed lowering. An increase in buckling height in sheets with different geometries of the same atomic species, beyond a certain limit, does not lead to change in the group velocity and the Debye temperature of the sheets
Enzymatic and non-enzymatic electrochemical glucose sensor based on carbon nano-onions
No full textA high sensitive glucose sensing characteristic has been realized in carbon nano-onions (CNOs). The CNOs of mean size 30 nm were synthesized by an energy-efficient, simple and inexpensive combustion technique. These as-synthesized CNOs could be employed as an electrochemical sensor by covalently immobilizing the glucose oxidase enzyme on them via carbodiimide chemistry. The sensitivity achieved by such a sensor is 26.5 mu A mM (1) cm (2) with a linear response in the range of 1-10 mM glucose. Further to improve the catalytic activity of the CNOs and also to make them enzyme free, platinum nanoparticles of average size 2.5 nm are decorated on CNOs. This sensor fabricated using Pt-decorated CNOs (Pt@CNOs) nanostructure has shown an enhanced sensitivity of 21.6 mu A mM (1) cm (2) with an extended linear response in the range of 2-28 mM glucose. Through these attempts we demonstrate CNOs as a versatile biosensing platform. (C) 2018 Elsevier B.V. All rights reserved
Stress enhanced calcium kinetics in a neuron
No full textAccurate modeling of the mechanobiological response of a Traumatic Brain Injury is beneficial toward its effective clinical examination, treatment and prevention. Here, we present a stress history-dependent non-spatial kinetic model to predict the microscale phenomena of secondary insults due to accumulation of excess calcium ions (Ca) induced by the macroscale primary injuries. The model is able to capture the experimentally observed increase and subsequent partial recovery of intracellular Ca concentration in response to various types of mechanical impulses. We further establish the accuracy of the model by comparing our predictions with key experimental observations
Circular Nanocavity in Ultrathin c-Si Solar Cell for Efficient Light Absorption
No full textIn this work, the effect of circular nanocavity on light trapping in a c-Si solar cell was studied by finite difference time domain (FDTD) simulation. The structure of the solar cell was considered to be Si3N4/c-Si/Ag, where the Ag layer was pattered and conformal growth of Si and Si3N4 was considered. The absorption spectra in the thin Si layer were determined and found 40 times higher at the infrared region (beyond 800nm). For qualitative analysis, the short-circuit current of the solar cell was determined computationally by AM 1.5G solar illumination and found to be 2.1 times higher in the case of nanocavity as that compared to un-patterned solar cell. The enhancement in absorption in the solar cell is attributed to the different plasmonic modes coupled in the thin c-Si layer. The incident angle-dependent study was performed to observe the effect on enhancement in wide-angle incidence. The thickness-dependent study confirms 2.1 to 1.75 times enhancement in short-circuit current in 100- to 250-nm-thick c-Si layer. Therefore, this observation suggests that this structure has good prospect in achieving high conversion efficiency while reducing the device cost
Correlation trends in the magnetic hyperfine structure of atoms: A relativistic coupled-cluster case study
No full textThe role of electron correlation in the hyperfine structure of alkali metals and alkaline earth metal monopositive ions in their ground electronic configuration is investigated using the Z-vector method in a relativistic coupled-cluster regime within the singles and doubles approximation. The systematic effects of core-correlating functions, polarization of core electrons, and high-lying virtual functions on core electrons correlation are studied. The study reveals that the core-correlating function plays a significant role in core polarization and thus is very important for precise calculation of the wave function near the nuclear region. The inner-core electrons (1s-2p) require very high virtual energy functions for proper correlation. Therefore, the all-electron correlation treatment and the inclusion of higher-energy virtual functions are the key factors for precise calculation of the hyperfine structure constant of atoms. Our calculated values are in excellent agreement with the available experimental values, which also implies that the wave function produced by the Z-vector method is accurate enough for further calculation of the parity- and time-reversal symmetry-violating properties in atoms and molecules