148 research outputs found
Development of a high-density CHO-C system enables rapid protein production in 10 days
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Enhanced Optical Trapping
Optical tweezers have contributed substantially to the advancement of micro-manipulation. However, they do have restrictions, mainly the limited range of materials that yield to optical trapping. Here we propose a method of employing optically trapped objects to manipulate the surrounding fluid and thus particles freely diffusing within it. We create and investigate a reconfigurable active-feedback system of optically trapped actuators, capable of manipulating translational and rotational motion of one or more nearby free objects
Cavity design in woodpile based 3D photonic crystals
In this paper, we present a design of a three-dimensional (3D) photonic crystal (PhC) nanocavity based on an optimized woodpile structure. By carefully choosing the position of the defect at the lattice center, we can create a cavity with high symmetry which supports well confined Gaussian-like cavity modes similar to those seen in a Fabry Perot laser resonator. We could also tune the resonant frequency of the cavity and manually choose the cavity mode order by adjusting the size of the defect at a chosen position
Harnessing multi-photon absorption to produce three-dimensional magnetic structures at the nanoscale
Three-dimensional nanostructured magnetic materials have recently been the topic of intense interest since they provide access to a host of new physical phenomena. Examples include new spin textures that exhibit topological protection, magnetochiral effects and novel ultrafast magnetic phenomena such as the spin-Cherenkov effect. Two-photon lithography is a powerful methodology that is capable of realising 3D polymer nanostructures on the scale of 100 nm. Combining this with postprocessing and deposition methodologies allows 3D magnetic nanostructures of arbitrary geometry to be produced. In this article, the physics of two-photon lithography is first detailed, before reviewing the studies to date that have exploited this fabrication route. The article then moves on to consider how non-linear optical techniques and post-processing solutions can be used to realise structures with a feature size below 100 nm, before comparing two-photon lithography with other direct write methodologies and providing a discussion on future developments
Evidence of near-infrared partial photonic bandgap in polymeric rod-connected diamond structures
We present the simulation, fabrication, and optical characterization of
low-index polymeric rod-connected diamond (RCD) structures. Such complex
three-dimensional photonic crystal structures are created via direct laser
writing by two-photon polymerization. To our knowledge, this is the first
measurement at near-infrared wavelengths, showing partial photonic bandgaps for
this structure. We characterize structures in transmission and reflection using
angular resolved Fourier image spectroscopy to visualize the band structure.
Comparison of the numerical simulations of such structures with the
experimentally measured data show good agreement for both P- and
S-polarizations
Enhanced UV/blue fluorescent sensing using metal-dielectric-metal aperture nanoantenna arrays
Subwavelength aperture antenna arrays are designed and fabricated for potential applications in fluorescence sensing in the near UV/blue range. They are designed using finite-difference time-domain (FDTD) simulation, fabricated using focused ion beam etching and characterised using angular Fourier spectroscopy. The aperture arrays are formed in the top layer of an aluminum-silica-aluminum trilayer and produce a maximum simulated field intensity enhancement of 5.8 times at 406 nm and highly directive emission with a beamwidth of 8.3 deg. The normal incidence reflection response has been measured and shows reasonable agreement with modelled results. In addition, to investigate higher field intensity enhancements, bowtie aperture arrays are simulated and the influence of parameters such as dielectric gap, position of dipole source, and aperture shape and size are discussed and show enhancements up to 67 times are possible
Caffeic acid phenethyl amide ameliorates ischemia/reperfusion injury and cardiac dysfunction in streptozotocin-induced diabetic rats
BACKGROUND: Caffeic acid phenethyl ester (CAPE) has been shown to protect the heart against ischemia/reperfusion (I/R) injury by various mechanisms including its antioxidant effect. In this study, we evaluated the protective effects of a CAPE analog with more structural stability in plasma, caffeic acid phenethyl amide (CAPA), on I/R injury in streptozotocin (STZ)-induced type 1 diabetic rats. METHODS: Type 1 diabetes mellitus was induced in Sprague–Dawley rats by a single intravenous injection of 60 mg/kg STZ. To produce the I/R injury, the left anterior descending coronary artery was occluded for 45 minutes, followed by 2 hours of reperfusion. CAPA was pretreated intraperitoneally 30 minutes before reperfusion. An analog devoid of the antioxidant property of CAPA, dimethoxyl CAPA (dmCAPA), and a nitric oxide synthase (NOS) inhibitor (Nω-nitro-l-arginine methyl ester [l-NAME]) were used to evaluate the mechanism involved in the reduction of the infarct size following CAPA-treatment. Finally, the cardioprotective effect of chronic treatment of CAPA was analyzed in diabetic rats. RESULTS: Compared to the control group, CAPA administration (3 and 15 mg/kg) significantly reduced the myocardial infarct size after I/R, while dmCAPA (15 mg/kg) had no cardioprotective effect. Interestingly, pretreatment with a NOS inhibitor, (l-NAME, 3 mg/kg) eliminated the effect of CAPA on myocardial infarction. Additionally, a 4-week CAPA treatment (1 mg/kg, orally, once daily) started 4 weeks after STZ-induction could effectively decrease the infarct size and ameliorate the cardiac dysfunction by pressure-volume loop analysis in STZ-induced diabetic animals. CONCLUSIONS: CAPA, which is structurally similar to CAPE, exerts cardioprotective activity in I/R injury through its antioxidant property and by preserving nitric oxide levels. On the other hand, chronic CAPA treatment could also ameliorate cardiac dysfunction in diabetic animals
Microstructure-Stabilized Blue Phase Liquid Crystals
We show that micron-scale two-dimensional (2D) honeycomb microwells can
significantly improve the stability of blue phase liquid crystals (BPLCs).
Polymeric microwells made by direct laser writing improve various features of
the blue phase (BP) including a dramatic extension of stable temperature range
and a large increase both in reflectivity and thermal stability of the
reflective peak wavelength. These results are mainly attributed to the
omni-directional anchoring of the isotropically oriented BP molecules at the
polymer walls of the hexagonal microwells and at the top and bottom substrates.
This leads to an omni-directional stabilization of the entire BPLC system. This
study not only provides a novel insight into the mechanism for the BP formation
in the 2D microwell but also points to an improved route to stabilize BP using
2D microwell arrays.Comment: 16 pages, 5 figure
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