Circular domains in phase-separated lipid vesicles with symmetric leaflet composition commonly exhibit three stable morphologies: flat, dimpled, and budded. However, stable dimples (i.e., partially budded domains) pre...
详细信息
Circular domains in phase-separated lipid vesicles with symmetric leaflet composition commonly exhibit three stable morphologies: flat, dimpled, and budded. However, stable dimples (i.e., partially budded domains) present a puzzle since simple elastic theories of domain shape predict that only flat and spherical budded domains are mechanically stable in the absence of spontaneous curvature. We argue that this inconsistency arises from the failure of the constant surface tension ensemble to properly account for the effect of entropic bending fluctuations. Formulating membrane elasticity within an entropic tension ensemble, wherein tension represents the free energy cost of extracting membrane area from thermal bending of the membrane, we calculate a morphological phase diagram that contains regions of mechanical stability for each of the flat, dimpled, and budded domain morphologies.
作者：
Haack, S.J.Taylor, T.M.Cybyk, B.Z.Foster, C.H.Alvi, F.S.The Johns Hopkins University
Applied Physics Laboratory Global Engagement Department 11100 Johns Hopkins Road Laurel MD 20723 United States
Florida A and M University Florida State University Mechanical Engineering Department 2525 Pottsdamer St Tallahassee FL 32310 United States
A variety of active flow control (AFC) methods have been successfully applied to low speed flows;however, AFC techniques available for high-speed, supersonic applications are very limited. Under the Air Force Office o...
详细信息
ISBN:
(纸本)9781624101472
A variety of active flow control (AFC) methods have been successfully applied to low speed flows;however, AFC techniques available for high-speed, supersonic applications are very limited. Under the Air Force Office of Scientific Research sponsorship, The Johns Hopkins University appliedphysics Laboratory (JHU/APL) and Florida State University/Florida Center for Advanced Aero-Propulsion (FSU/FCAAP) are investigating a device intended for high-speed flow control called the Spark Jet actuator, which manipulates high-speed flows without active mechanical components. Previous characterization efforts of the SparkJet, invented by JHU/APL, include computational and experimental techniques over a variety of operating conditions in quiescent flow. To characterize the SparkJet in supersonic flow conditions, a supersonic wind tunnel test will be conducted by FSU using their facilities. To properly design a SparkJet array for wind tunnel testing, characterization efforts have turned toward array design variations and Spark Jet operation in conditions similar to the wind tunnel. The SparkJet array and supporting electronics design will depend on the efficiency of the SparkJet under various conditions. This paper focuses on understanding the energy transfer efficiency of the spark discharge from stored capacitor energy to heating the cavity air in quiescent flow and low pressure conditions. Previous experimental efforts included the use of high-resolution particle image velocimetry and digital speckle tomography. While these tests gave useful results, heat transferred to the air inside the cavity remained difficult to quantify experimentally. The results presented in this paper are a continuation of SparkJet characterization studies with a focus on estimating the efficiency by three experimental techniques: cavity pressure measurements, high-quality micro-Schlieren images acquisition for velocity measurements and Joule heat measurements. Computational Fluid Dynamic simulations
Vast numbers of bronze coins have been, and continue to be, excavated from archaeological sites around the Greco-Roman world. While often of little value from a strictly numismatic point of view, these coins provide i...
详细信息
Temperatures, pressures and velocities were measured in a Ranque-Hilsch vortex tube. Results show that the cooling power is larger than the heating power due to a heat loss to the surroundings. This heat loss became t...
Temperatures, pressures and velocities were measured in a Ranque-Hilsch vortex tube. Results show that the cooling power is larger than the heating power due to a heat loss to the surroundings. This heat loss became the more dominant thermodynamic process at large cold fractions (the ratio of cold mass flow over total mass flow). The velocities were obtained by means of Laser Doppler Anemometry. By this method, the three dimensional velocities of the gas and their standard deviations in the vortex tube are revealed by an non-intrusive measurement method. The turbulent fluctuations, characterized by the standard deviations, show that the turbulence is isotropic in the core region of the vortex tube.
This work demonstrates a method to develop high temperature metal-semiconductor-metal photodetectors using low-temperature, ion beam assisted deposition of nanocrystalline silicon carbide (SiC) and hydrothermal synthe...
详细信息
We investigate the vibrational properties of ultrananocrystalline diamond (UNCD) using molecular dynamics simulations. We compare the vibrational spectra of two UNCD models of average grain size 2 and 4 nm with single...
详细信息
We investigate the vibrational properties of ultrananocrystalline diamond (UNCD) using molecular dynamics simulations. We compare the vibrational spectra of two UNCD models of average grain size 2 and 4 nm with single crystal diamond and an isolated nanodiamond (ND) particle. The vibrational spectra of the ND particle and UNCD models exhibit the effect of phonon confinement as well as undercoordinated atoms at the surface/interfaces. This is further reflected in the specific heat of UNCD models and the ND particle that showed enhancements over that of single crystal diamond. The excess specific heat in UNCD models in comparison to single crystal diamond is found to be maximum at approximately 350 K.
The effect on the selection of different plasma chemistries for simulating a typical dielectric barrier discharge (DBD) driven by quasi-pulsed power source (20 kHz) is investigated. The numerical simulation was perfor...
详细信息
The present work proposes a new set of orthogonal hybrid functions (HF) which evolved from synthesis of orthogonal sample-and-hold functions (SHF) and triangular functions (TF). The HF set is used to approximate a tim...
详细信息
The present work proposes a new set of orthogonal hybrid functions (HF) which evolved from synthesis of orthogonal sample-and-hold functions (SHF) and triangular functions (TF). The HF set is used to approximate a time function in a piecewise linear manner. The algorithm of one-shot operational matrices for integration of different orders in HF domain are derived and employed for more accurate multiple integration and solution of third order non-homogeneous differential equations. The results are compared with the exact solution and the results obtained via 4 th order Runge-Kutta method.
This paper reports a multifunctional optical sensor platform based on the microelectromechanical systems (MEMS) technology with the aim to miniaturize conventional bulky optical measurement systems for space-constrain...
详细信息
This paper reports a multifunctional optical sensor platform based on the microelectromechanical systems (MEMS) technology with the aim to miniaturize conventional bulky optical measurement systems for space-constrained applications and harsh environment. Small discrete optical components are integrated onto a printed circuit board by using optical fibers as the waveguide. Low-coherence interferometry is used for modulation and retrieval of the sensing signal. The whole optical system including the related circuit takes up a footprint of 2.2" × 1.5". To test the functionality, a fiber-tip pressure sensor is interrogated using this platform. The successful demonstration suggests that this platform can be used for optical measurement in the sensor node of Wireless Sensor Networks (WSNs).
To avoid the difficult-to-solve optimized effective potential (OEP) integral equation, we introduce an efficient direct minimization scheme for performing OEP calculations within Kohn–Sham density functional theory (...
详细信息
To avoid the difficult-to-solve optimized effective potential (OEP) integral equation, we introduce an efficient direct minimization scheme for performing OEP calculations within Kohn–Sham density functional theory (KS-DFT). We reformulated the functional derivative of the total energy with respect to the KS effective potential in terms of efficient finite differences. Our method only uses the orbitals involved in the construction of the KS exchange-correlation functionals. We demonstrate our scheme by performing exact-exchange OEP for sodium clusters, in which only occupied KS orbitals are needed to obtain the OEP. Our efficient direct minimization scheme should aid future development of orbital-dependent density functionals and render OEP to be a practical choice for various applications.
暂无评论