Red blood cells and other non-spherical capsules in shear flow: oscillatory dynamics and the tank-treading-to-tumbling transition

We consider the motion of red blood cells and other non-spherical microcapsules dilutely suspended in a simple shear flow. Our analysis indicates that depending on the viscosity, membrane elasticity, geometry and shear rate, the particle exhibits either tumbling, tank-treading of the membrane about the viscous interior with periodic oscillations of the orientation angle, or intermittent behavior in which the two modes occur alternately. For red blood cells, we compute the complete phase diagram and identify a novel tank-treading-to-tumbling transition at low shear rates. Observations of such motions coupled with our theoretical framework may provide a sensitive means of assessing capsule properties.Comment: 11 pages, 4 figure

Origin of ferromagnetism in (Zn,Co)O from magnetization and spin-dependent magnetoresistance

In order to elucidate the nature of ferromagnetic signatures observed in (Zn,Co)O we have examined experimentally and theoretically magnetic properties and spin-dependent quantum localization effects that control low-temperature magnetoresistance. Our findings, together with a through structural characterization, substantiate the model assigning spontaneous magnetization of (Zn,Co)O to uncompensated spins at the surface of antiferromagnetic nanocrystal of Co-rich wurtzite (Zn,Co)O. The model explains a large anisotropy observed in both magnetization and magnetoresistance in terms of spin hamiltonian of Co ions in the crystal field of the wurtzite lattice.Comment: 6 pages, 6 figure

Swinging of red blood cells under shear flow

We reveal that under moderate shear stress (of the order of 0.1 Pa) red blood cells present an oscillation of their inclination (swinging) superimposed to the long-observed steady tanktreading (TT) motion. A model based on a fluid ellipsoid surrounded by a visco-elastic membrane initially unstrained (shape memory) predicts all observed features of the motion: an increase of both swinging amplitude and period (1/2 the TT period) upon decreasing the shear stress, a shear stress-triggered transition towards a narrow shear stress-range intermittent regime of successive swinging and tumbling, and a pure tumbling motion at lower shear stress-values.Comment: 4 pages 5 figures submitted to Physical Review Letter

Quantum limited particle sensing in optical tweezers

Particle sensing in optical tweezers systems provides information on the position, velocity and force of the specimen particles. The conventional quadrant detection scheme is applied ubiquitously in optical tweezers experiments to quantify these parameters. In this paper we show that quadrant detection is non-optimal for particle sensing in optical tweezers and propose an alternative optimal particle sensing scheme based on spatial homodyne detection. A formalism for particle sensing in terms of transverse spatial modes is developed and numerical simulations of the efficacy of both quadrant and spatial homodyne detection are shown. We demonstrate that an order of magnitude improvement in particle sensing sensitivity can be achieved using spatial homodyne over quadrant detection.Comment: Submitted to Biophys

The Use of Colorful Semantics to Improve Sentence Construction in Writing Sentences Among Year Four Pupils

This action research was set out to develop pupils' writing skill using colorful semantics. The main two objectives established from the outset were to develop pupils' sentence construction and improve my teaching practice in sentence construction teaching respectively. As the researcher, I conducted this classroom action research to 31 pupils which comprised 17 males and 14 females of Year 4J of SJK(C) Cheng Siu 2 in Malaysia. The data was gathered through pre- writing test and post- writing test, pupils' work as well as teacher's reflective journal. Over the course of four weeks, I introduced colorful semantics to my pupils in accordance to the sequence of ‘who', ‘what doing', ‘what' and ‘where'. As can be induced from the findings, colorful semantics was statistically significant to pupils' sentence construction through the enhancement of pupils' ability to understand words of each sentence part and also to write sentence in the correct order. The findings also depicted that utilization of colorful semantics improved my teaching practice to become a reflective, passionate, and motivational teacher. Therefore, the positive results warrant further research into colorful semantics with suggestions to integrate Information, Communication, and Technology (ICT) into lessons and expose pupils to more sentence types

Dependence of Adhesion Properties on Blend Ratio of Ethylene-Propylene-Diene Rubber/Standard Malaysian Rubber Blend Adhesive

Viscosity, tack and, peel and shear strengths of ethylene-propylene-diene rubber (EPDM)/standard Malaysian rubber (SMR L) blend adhesive were studied using various blend ratios of the two rubbers, ranging from 0 to 100% EPDM. Coumarone-indene resin, toluene, and poly(ethylene terephthalate) (PET) were used as the tackifier, solvent, and coating substrate, respectively. The tackifier content was fixed at 40 parts per hundred parts of rubber (phr). A SHEEN hand coater was used to coat the adhesive on PET film at four coating thicknesses, that is, 30, 60, 90, and 12

Adhesion Properties of Acrylonitrile-Butadiene Rubber/Standard Malaysian Rubber Blend Based Pressure-Sensitive Adhesive

Viscosity and adhesion properties of NBR/SMR L blend based pressure-sensitive adhesive were investigated using coumaroneindene resin, toluene, and poly(ethylene terephthalate) (PET) as tackifier, solvent, and coating substrate, respectively. Coumaroneindene resin content was fixed at 40 parts per hundred parts of rubber (phr) in the adhesive formulation.The ratio of NBR/SMR L blend used was 0, 20, 40, 60, 80, and 100% of NBR content. Four different thicknesses, that is, 30, 60, 90, and 12