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surface curvature

Naiyin Yu, Abhijit Ghosh, Michael F Hagan
We use computer simulations and simple theoretical models to analyze the morphologies that result when rod-like particles end-attach onto a curved surface, creating a finite-thickness monolayer aligned with the surface normal. This geometry leads to two forms of frustration, one associated with the incompatibility of hexagonal order on surfaces with Gaussian curvature, and the second reflecting the deformation of a layer with finite thickness on a surface with non-zero mean curvature. We show that the latter effect leads to a faceting mechanism...
October 17, 2016: Soft Matter
Gaoxing Su, Xiaofei Zhou, Hongyu Zhou, Ye Li, Xianren Zhang, Yin Liu, Dapeng Cao, Bing Yan
Understandings of how biomolecules modify nanoparticles in a biological context and how these exchanges impact nano-bio interactions are fundamental to nanomedicine and nanotoxicology research. In this work, cancer-targeting gold nanoparticles (TGNPs) with different sizes (5, 15, and 40 nm) were designed and synthesized. These nanoparticles spontaneously adsorbed proteins in complete cell culture medium (DMEM with 10% human serum). Although the targeting ligands on the surface of nanoparticles were likely to be shielded by adsorbed proteins, the targeting capability of nanoparticles was maintained due to the highly dynamic nature of protein adsorption...
October 17, 2016: ACS Applied Materials & Interfaces
Yan Sun, Yang Zhang, Claudia Felser, Binghai Yan
Since their discovery, topological insulators are expected to be ideal spintronic materials owing to the spin currents carried by surface states with spin-momentum locking. However, the bulk doping problem remains an obstacle that hinders such an application. In this work, we predict that a newly discovered family of topological materials, the Weyl semimetals, exhibits a large intrinsic spin Hall effect that can be utilized to generate and detect spin currents. Our ab initio calculations reveal a large spin Hall conductivity in the TaAs family of Weyl materials...
September 30, 2016: Physical Review Letters
Majid Ahmadlouydarab, Chuanjin Lan, Arup Kumar Das, Yanbao Ma
While there are intensive studies on the coalescence of sessile macroscale droplets, there is little study on the coalescence of sessile microdroplets. In this paper, the coalescence process of two sessile microdroplets is studied by using a many-body dissipative particle dynamics numerical method. A comprehensive parametric study is conducted to investigate the effects on the coalescence process from the wettability gradient, hydrophilicity of the solid surface, and symmetric or asymmetric configurations. A water bridge is formed after two microdroplets contact...
September 2016: Physical Review. E
Prashant Pendyala, Harpreet Singh Grewal, Hong Nam Kim, Il-Joo Cho, Eui-Sung Yoon
Nanoscale patterns have dimensions that are comparable to the length scales affected by intermolecular and surface forces. In this study, we systematically investigated the individual roles of curvature, surface energy, lateral stiffness, material, pattern density on the characteristics of the adhesion and friction of nanopatterns. For this purpose, we used a combination of capillary force lithography and nanodrawing methods to fabricate cylindrical and mushroom-shaped pillars with flat- and round-top morphologies...
October 14, 2016: ACS Applied Materials & Interfaces
Colin James Stockdale Klaus, Krishnan Raghunathan, Emmanuele DiBenedetto, Anne K Kenworthy
Diffusion of particles in curved surfaces is inherently complex compared with diffusion in a flat membrane owing to the non-planarity of the surface. The consequence of such non-planar geometry on diffusion is poorly understood but is highly relevant in the case of cell membranes, which often adopt complex geometries. To address this question, we developed a new finite element approach to model diffusion on curved membrane surfaces based on solutions to Fick's law of diffusion and used this to study the effects of geometry on the entry of surface-bound particles into tubules by diffusion...
October 12, 2016: Molecular Biology of the Cell
N Apurva Ratan Murty, Sripati Panditaradhyula Arun
We have no difficulty seeing a straight line drawn on a paper even when the paper is bent, but this inference is in fact nontrivial. Doing so requires either matching of local features or representing the pattern after factoring out the surface shape. Here we show that single neurons in the monkey inferior temporal cortex show invariant responses to patterns across rigid and non-rigid changes of surfaces. We recorded neuronal responses to stimuli in which the pattern and the surrounding surface were varied independently...
October 12, 2016: Journal of Neurophysiology
Nazlee Zebardast, Srinivasan Kavitha, Palaniswamy Krishnamurthy, David S Friedman, Monisha E Nongpiur, Tin Aung, Harry A Quigley, Pradeep Y Ramulu, Rengaraj Venkatesh
PURPOSE: To compare anterior segment optical coherence tomography (ASOCT) angle morphology before and after laser peripheral iridotomy (LPI) in a cohort of South Indian subjects with primary angle-closure suspect (PACS) or primary angle-closure/primary angle-closure glaucoma (PAC/PACG) and to examine baseline parameters associated with angle widening. DESIGN: Prospective observational study. PARTICIPANTS: A total of 244 subjects aged ≥30 years with PACS or PAC/PACG in at least 1 eye...
October 7, 2016: Ophthalmology
Akshit Peer, Rabin Dhakal, Rana Biswas, Jaeyoun Kim
We compare the rates of drug release from nanopatterned and flat biodegradable polymer surfaces, and observe significantly lower release rates from the nanopatterned surfaces. Specifically, we nanopattern poly(l-lactic acid) (PLLA), a biodegradable polymer frequently used for fabricating drug-eluting coronary stents, through microtransfer molding and solvent casting and investigate the nanopattern's impact on the release of sirolimus, an immunosuppressant agent, coated on the PLLA surface using high performance liquid chromatography/mass spectrometry...
October 5, 2016: Nanoscale
Shawkat Ali, Arshad Hassan, Jinho Bae, Chong Hyun Lee, Juho Kim
Since printed resistance temperature detectors (RTDs) is affected by tension and compression of metallic pattern on flexible or curved surfaces, a significant temperature sensing error is occurred in general. Hence, we propose differential temperature sensor (DTS) to compensate the bending effect of the printed RTDs, which is composed of two serially connected similar meander patterns fabricated back-to-back on the polyimide polyethyleneterephthalate (PET) substrate through inkjet printer Dimatix DMP-3000 by using silver nanoparticles...
October 8, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Duc D Nguyen, Guo-Wei Wei
This article explores the impact of surface area, volume, curvature, and Lennard-Jones (LJ) potential on solvation free energy predictions. Rigidity surfaces are utilized to generate robust analytical expressions for maximum, minimum, mean, and Gaussian curvatures of solvent-solute interfaces, and define a generalized Poisson-Boltzmann (GPB) equation with a smooth dielectric profile. Extensive correlation analysis is performed to examine the linear dependence of surface area, surface enclosed volume, maximum curvature, minimum curvature, mean curvature, and Gaussian curvature for solvation modeling...
October 8, 2016: Journal of Computational Chemistry
Sang-Mok Lee, Hyuk Jin Choi, Heejin Choi, Mee Kum Kim, Won Ryang Wee
: BACKGROUND: Though the development and fitting of scleral contact lenses are expanding steadily, there is no simple method to provide scleral metrics for scleral contact lens fitting yet. The aim of this study was to establish formulae for estimation of the axial radius of curvature (ARC) of the anterior sclera using ocular biometric parameters that can be easily obtained with conventional devices. METHODS: A semi-automated stitching method and a computational analysis tool for calculating ARC were developed by using the ImageJ and MATLAB software...
October 7, 2016: BMC Ophthalmology
A J Sodt, R M Venable, E Lyman, R W Pastor
The unique properties of the individual lipids that compose biological membranes together determine the energetics of the surface. The energetics of the surface, in turn, govern the formation of membrane structures and membrane reshaping processes, and thus they will underlie cellular-scale models of viral fusion, vesicle-dependent transport, and lateral organization relevant to signaling. The spontaneous curvature, to the best of our knowledge, is always assumed to be additive. We describe observations from simulations of unexpected nonadditive compositional curvature energetics of two lipids essential to the plasma membrane: sphingomyelin and cholesterol...
September 23, 2016: Physical Review Letters
Zhi-Chun Shao, Yan Zhao, Wanyu Zhang, Yanping Cao, Xi-Qiao Feng
Sinusoidal wrinkling will occur in a planar film-substrate bilayer when the uniaxial compressive strain imposed to the system exceeds a critical value. However, when a core-shell soft cylinder is subjected to axial compression, surface wrinkling patterns may evolve from the sinusoidal mode to the diamond-like mode, depending on the modular ratio and the curvature of the system. Inspired by this phenomenon, we here propose a simple yet robust strategy to fabricate hierarchical wrinkling patterns by controlling the curvature of a film-substrate system...
September 28, 2016: Soft Matter
Do-Kyun Kwon, Su Jeong Lee, Jae-Min Myoung
In this work, vertically aligned zinc oxide (ZnO) nanorod (NR)-based flexible ultraviolet (UV) photodetectors were successfully fabricated on a polyimide (PI) substrate with a copper (Cu) nanowire (NW) electrode. To enhance the flexibility and sensing properties, the entangled networks of Cu NWs were applied to UV photodetectors as a flexible electrode. Here, Cu NWs have a high conductivity with a low cost compared to other metals to achieve a Schottky contact with ZnO NRs. Moreover, because of forming a network structure, the surface of the sensing material has a large contact area with oxygen molecules, resulting in a faster response time...
September 22, 2016: Nanoscale
R Pompili, M P Anania, F Bisesto, M Botton, M Castellano, E Chiadroni, A Cianchi, A Curcio, M Ferrario, M Galletti, Z Henis, M Petrarca, E Schleifer, A Zigler
Highly energetic electrons are generated at the early phases of the interaction of short-pulse high-intensity lasers with solid targets. These escaping particles are identified as the essential core of picosecond-scale phenomena such as laser-based acceleration, surface manipulation, generation of intense magnetic fields and electromagnetic pulses. Increasing the number of the escaping electrons facilitate the late time processes in all cases. Up to now only indirect evidences of these important forerunners have been recorded, thus no detailed study of the governing mechanisms was possible...
October 7, 2016: Scientific Reports
David A Quint, Ajay Gopinathan, Gregory M Grason
Motivated to understand the behavior of biological filaments interacting with membranes of various types, we employ a theoretical model for the shape and thermodynamics of intrinsically helical filaments bound to curved membranes. We show that filament-surface interactions lead to a host of nonuniform shape equilibria, in which filaments progressively unwind from their native twist with increasing surface interaction and surface curvature, ultimately adopting uniform-contact curved shapes. The latter effect is due to nonlinear coupling between elastic twist and bending of filaments on anisotropically curved surfaces such as the cylindrical surfaces considered here...
October 4, 2016: Biophysical Journal
Elina Bengtsson, Malin Persson, Mohammad A Rahman, Saroj Kumar, Hideyo Takatsuki, Alf Månsson
Actin filaments have key roles in cell motility but are generally claimed to be passive interaction partners in actin-myosin-based motion generation. Here, we present evidence against this static view based on an altered myosin-induced actin filament gliding pattern in an in vitro motility assay at varied [MgATP]. The statistics that characterize the degree of meandering of the actin filament paths suggest that for [MgATP] ≥ 0.25 mM, the flexural rigidity of heavy meromyosin (HMM)-propelled actin filaments is similar (without phalloidin) or slightly lower (with phalloidin) than that of HMM-free filaments observed in solution without surface tethering...
October 4, 2016: Biophysical Journal
Wen-Jie Chen, Meng Xiao, C T Chan
Weyl points, as monopoles of Berry curvature in momentum space, have captured much attention recently in various branches of physics. Realizing topological materials that exhibit such nodal points is challenging and indeed, Weyl points have been found experimentally in transition metal arsenide and phosphide and gyroid photonic crystal whose structure is complex. If realizing even the simplest type of single Weyl nodes with a topological charge of 1 is difficult, then making a real crystal carrying higher topological charges may seem more challenging...
October 5, 2016: Nature Communications
Prasenjit Kabi, Swetaprovo Chaudhuri, Saptarshi Basu
Surface patterning with functional colloids is an important research area due to its widespread applicability in domains ranging from nano-electronics, pharmaceutics, semi-conductors, photovoltaics among others. To this endeavour, we propose a low-cost patterning technique that aspires to eliminate the more expensive methodologies presently in practise. Using a simple document stamp on which patterns of any geometry can be embossed, we are able to print two-dimensional mm-scale "wall-less confinement" using ink based hydrophobic fence on any plasma treated superhydrophilic surface...
October 4, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
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