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Bafkar O, Cajas J, Calmet H, Houzeaux G, Rosengarten G, Lester D, Nguyen V, Gulizia S, Cole I. Impact of sleeping position, gravitational force & tissue stiffness on obstructive sleep apnoea. Sleep Med 2019. [DOI: 10.1016/j.sleep.2019.11.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Herringer JW, Lester D, Dorrington GE, Rosengarten G. Can diatom girdle band pores act as a hydrodynamic viral defense mechanism? J Biol Phys 2019; 45:213-234. [PMID: 31140117 DOI: 10.1007/s10867-019-09525-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 04/12/2019] [Indexed: 10/26/2022] Open
Abstract
Diatoms are microalgae encased in highly structured and regular frustules of porous silica. A long-standing biological question has been the function of these frustules, with hypotheses ranging from them acting as photonic light absorbers to being particle filters. While it has been observed that the girdle band pores of the frustule of Coscinodiscus sp. resemble those of a hydrodynamic drift ratchet, we show using scaling arguments and numerical simulations that they cannot act as effective drift ratchets. Instead, we present evidence that frustules are semi-active filters. We propose that frustule pores simultaneously repel viruses while promoting uptake of ionic nutrients via a recirculating, electroosmotic dead-end pore flow, a new mechanism of "hydrodynamic immunity".
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Affiliation(s)
- J W Herringer
- School of Engineering, RMIT University, Carlton, Melbourne, Victoria, 3053, Australia.
| | - D Lester
- School of Engineering, RMIT University, Carlton, Melbourne, Victoria, 3053, Australia
| | - G E Dorrington
- School of Engineering, RMIT University, Carlton, Melbourne, Victoria, 3053, Australia
| | - G Rosengarten
- School of Engineering, RMIT University, Carlton, Melbourne, Victoria, 3053, Australia
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Molloy CP, Yao Y, Kammoun H, Bonnard T, Hoefer T, Alt K, Tovar-Lopez F, Rosengarten G, Ramsland PA, van der Meer AD, van den Berg A, Murphy AJ, Hagemeyer CE, Peter K, Westein E. Shear-sensitive nanocapsule drug release for site-specific inhibition of occlusive thrombus formation. J Thromb Haemost 2017; 15:972-982. [PMID: 28267256 DOI: 10.1111/jth.13666] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Indexed: 11/29/2022]
Abstract
Essentials Vessel stenosis due to large thrombus formation increases local shear 1-2 orders of magnitude. High shear at stenotic sites was exploited to trigger eptifibatide release from nanocapsules. Local delivery of eptifibatide prevented vessel occlusion without increased tail bleeding times. Local nanocapsule delivery of eptifibatide may be safer than systemic antiplatelet therapies. SUMMARY Background Myocardial infarction and stroke remain the leading causes of mortality and morbidity. The major limitation of current antiplatelet therapy is that the effective concentrations are limited because of bleeding complications. Targeted delivery of antiplatelet drug to sites of thrombosis would overcome these limitations. Objectives Here, we have exploited a key biomechanical feature specific to thrombosis, i.e. significantly increased blood shear stress resulting from a reduction in the lumen of the vessel, to achieve site-directed delivery of the clinically used antiplatelet agent eptifibatide by using shear-sensitive phosphatidylcholine (PC)-based nanocapsules. Methods PC-based nanocapsules (2.8 × 1012 ) with high-dose encapsulated eptifibatide were introduced into microfluidic blood perfusion assays and into in vivo models of thrombosis and tail bleeding. Results Shear-triggered nanocapsule delivery of eptifibatide inhibited in vitro thrombus formation selectively under stenotic and high shear flow conditions above a shear rate of 1000 s-1 while leaving thrombus formation under physiologic shear rates unaffected. Thrombosis was effectively prevented in in vivo models of vessel wall damage. Importantly, mice infused with shear-sensitive antiplatelet nanocapsules did not show prolonged bleeding times. Conclusions Targeted delivery of eptifibatide by shear-sensitive nanocapsules offers site-specific antiplatelet potential, and may form a basis for developing more potent and safer antiplatelet drugs.
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Affiliation(s)
- C P Molloy
- Atherothrombosis and Vascular Biology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Y Yao
- Atherothrombosis and Vascular Biology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - H Kammoun
- Haematopoiesis and Leukocyte Biology, Baker Heart & Diabetes Institute, Melbourne, Victoria, Australia
| | - T Bonnard
- Nano Biotechnology Laboratory, Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria, Australia
| | - T Hoefer
- Atherothrombosis and Vascular Biology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - K Alt
- Nano Biotechnology Laboratory, Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria, Australia
| | - F Tovar-Lopez
- School of Engineering, RMIT University, Melbourne, Victoria, Australia
| | - G Rosengarten
- School of Engineering, RMIT University, Melbourne, Victoria, Australia
| | - P A Ramsland
- School of Science, RMIT University, Bundoora, Victoria, Australia
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria, Australia
- Department of Immunology, Monash University, Melbourne, Victoria, Australia
- Department of Surgery at Austin Health, University of Melbourne, Heidelberg, Victoria, Australia
| | - A D van der Meer
- MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, the Netherlands
| | - A van den Berg
- MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, the Netherlands
| | - A J Murphy
- Haematopoiesis and Leukocyte Biology, Baker Heart & Diabetes Institute, Melbourne, Victoria, Australia
| | - C E Hagemeyer
- Nano Biotechnology Laboratory, Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria, Australia
| | - K Peter
- Atherothrombosis and Vascular Biology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - E Westein
- Atherothrombosis and Vascular Biology, Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
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Gajic M, Karwa N, Mojiri A, Rosengarten G. Modeling reflection loss from an evacuated tube inside a compound parabolic concentrator with a cylindrical receiver. Opt Express 2015; 23:A493-A501. [PMID: 26072874 DOI: 10.1364/oe.23.00a493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Linear compound parabolic concentrators with cylindrical receivers are often combined with evacuated tubes along their focal length to suppress convective heat loss for use as thermal collectors. When investigating the optical efficiency of such collectors it is important to consider the reflection loss introduced by the evacuated tube particularly at large angles of incidence of light onto the CPC aperture. In this paper reflection losses are determined using ray-tracing as a function of the angle of incidence in both the longitudinal and transversal planes of a CPC. The reflection losses are found to be approximately constant except close to the maximum acceptance angle.
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Chrimes AF, Khodasevych I, Mitchell A, Rosengarten G, Kalantar-zadeh K. Dielectrophoretically controlled Fresnel zone plate. Lab Chip 2015; 15:1092-1100. [PMID: 25524620 DOI: 10.1039/c4lc01213e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Switchability is a highly sought after feature for planar optical systems. Suspensions of nanomaterials can be used for generating controllable changes in such systems. We report a planar diffractive microfluidic lens which integrates controlled dielectrophoresis (DEP) for trapping suspended nanomaterials. Silicon and tungsten oxide nanoparticle suspensions are used. These nanomaterials are trapped in such a way as to form alternating opaque and transparent rings using the DEP forces on demand. These rings form a planar diffractive Fresnel zone plate to focus the incident light. The Fresnel zone plate is tuned for the visible light region and the lens can be turned on (DEP applied) or off (DEP removed) in a controlled manner. This proof of concept demonstration can be further expanded for a variety of switchable optical devices and can be integrated with lab-on-a-chip and optofluidic devices.
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Affiliation(s)
- A F Chrimes
- School of Electrical and Computer Engineering, RMIT University, Melbourne, Australia.
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Domachuk P, Cronin-Golomb M, Eggleton B, Mutzenich S, Rosengarten G, Mitchell A. Application of optical trapping to beam manipulation in optofluidics. Opt Express 2005; 13:7265-75. [PMID: 19498750 DOI: 10.1364/opex.13.007265] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We introduce a novel method of attaining all-optical beam control in an optofluidic device by displacing an optically trapped microsphere through a light beam. The micro-sphere causes the beam to be refracted by various degrees as a function of the sphere position, providing tunable attenuation and beam-steering in the device. The device itself consists of the manipulated light beam extending between two buried waveguides which are on either side of a microfluidic channel. This channel contains the micro-spheres which are suspended in water. We simulate this geometry using the Finite Difference Time Domain method and find good agreement between simulation and experiment.
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Abstract
EPR investigations of a variety of irradiated materials have provided the potential for useful dosimetry applications. Herbs and spices imported into Australia have been investigated to establish whether or not they have been irradiated. Post-irradiation studies have shown that there is more than one free radical species in most cases which decay rapidly with time. Changes to transition metal ion signals, e.g., Cu2+ or Fe3+, appear to be permanent against further irradiation. Thus if these signals change upon irradiation, the material almost certainly has not previously been irradiated. Power saturation studies of alanine, a favored dosimetry material, suggest two distinguishable types of behavior consistent with the presence of spin-flip transitions. Irradiation of vanadium doped beryl yields stable VO2+ ions which may provide a useful dosimetry material. Dosimetry applications would appear to demand low cost, user friendly, automated EPR spectrometers. A patented option based on a 2.5 GHz microstrip microwave bridge will be described briefly.
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Affiliation(s)
- J R Pilbrow
- Department of Physics, Monash University, Clayton, Victoria, Australia
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