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Bonding effect of plasma-irradiated PET films can be preserved after soaking in various liquid reagents
No full textRestricted Access.To clarify the bonding mechanism for the plasma-irradiated PET films and the origin of the long lifetime of the bonding ability, we soaked the irradiated films in various types of liquid reagent, then tried to bond them by heat-pressing. The irradiated films do not lose the bonding ability after soaking in water, acid, alkali, and organic solvents, whereas they lose it after soaking in ionic solutions of AlCl3 and FeCl3. The COOH is created on the surface by the irradiation, but it is consumed by the chemical reaction with Al and Fe ions. This is the origin of the inactivation of the irradiated surface and the disappearance of the bonding ability after the soaking. The result supports our proposal of "dehydrated condensation reaction" concerning COOH as the bonding mechanism. The irradiated films should be stable in a normal atmosphere for a long time because they are not subjected to water, acid, alkali, and organic solvent
Investigation of the dynamical slowing down process in soft glassy colloidal suspensions: comparisons with supercooled liquids
No full textRestricted Access.The primary and secondary relaxation timescales of aging colloidal suspensions of Laponite are estimated from intensity autocorrelation functions obtained in dynamic light scattering (DLS) experiments. The dynamical slowing down of these relaxation processes are compared with observations in fragile supercooled liquids by establishing a one-to-one mapping between the waiting time since filtration of a Laponite suspension and the inverse of the temperature of a supercooled liquid that is rapidly quenched towards its glass transition temperature. New timescales associated with primary and secondary relaxation processes, such as the characteristic timescale associated with the slowdown of the secondary relaxation process and the glass transition time, are extracted to describe the phenomenon of dynamical arrest in Laponite suspensions. In results that are strongly reminiscent of those extracted from supercooled liquids approaching their glass transitions, it is demonstrated that a strong coupling exists between the primary and secondary relaxation processes of aging Laponite suspensions in the cage-forming regime. Furthermore, the experimental data presented here clearly demonstrate the self-similar nature of the aging dynamics of Laponite suspensions within a range of sample concentrations
The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14 110 Compact Radio Sources over 6 100 Square Degrees
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We present the results of an approximately 6 100 deg2 104–196 MHz radio sky survey performed with the Murchison Widefield Array during instrument commissioning between 2012 September and 2012 December: the MWACS. The data were taken as meridian drift scans with two different 32-antenna sub-arrays that were available during the commissioning period. The survey covers approximately 20.5 h < RA < 8.5 h, − 58° < Dec < −14°over three frequency bands centred on 119, 150 and 180 MHz, with image resolutions of 6–3 arcmin. The catalogue has 3 arcmin angular resolution and a typical noise level of 40 mJy beam− 1, with reduced sensitivity near the field boundaries and bright sources. We describe the data reduction strategy, based upon mosaicked snapshots, flux density calibration, and source-finding method. We present a catalogue of flux density and spectral index measurements for 14 110 sources, extracted from the mosaic, 1 247 of which are sub-components of complexes of sources
Chiral symmetry breaking dictated by electric-field-driven shape transitions of nucleating conglomerate domains in a bent-core liquid crystal
No full textOpen AccessGenerating and controlling chiral symmetry breaking and enantiomeric excess is not only interesting from a fundamental perspective but can also lead to novel functional materials. In this work, we show how the dark conglomerate (DC) liquid crystalline phase characterized by macroscopic chiral domains offers such a possibility if formed under an electric field. In addition the chiral domains are electro-optically switchable. The chiral segregation in the DC phase can be tuned by using dc or ac fields at different frequencies. Consequently, the enantioselectivity, dielectric parameters and switching polarization in the DC phase become tunable. Another interesting aspect is that the nucleating conglomerate domains formed under ac fields exhibit frequency dependent shape transitions which have a striking resemblance to domain shape changes observed in two-dimensional monolayers. This can therefore be used as a model experimental system to get a physical insight into the effects of chiral and electrostatic interactions, under external fields, on domain growth and interface structures. The domain shape transitions can also be used to investigate the role of growth morphology in coarsening and scaling hypotheses. From a technological point of view this opens up the possibility of obtaining chiral thin films with preferential sense of chirality which can be useful in chiroptical and nonlinear optical applications
The KaVA and KVN pulsar project
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We present our work towards using the Korean VLBI (Very Long Baseline Interferometer) Network (KVN) and VLBI Exploration of Radio Astronomy (VERA) arrays combined into the KVN and VERA Array (KaVA) for observations of radio pulsars at high frequencies (≃ 22 GHz). Pulsar astronomy is generally focused at frequencies approximately 0.3 to several GHz and pulsars are usually discovered and monitored with large, single-dish, radio telescopes. For most pulsars, reduced radio flux is expected at high frequencies due to their steep spectrum, but there are exceptions where high frequency observations can be useful. Moreover, some pulsars are observable at high frequencies only, such as those close to the Galactic Center. The discoveries of a radio-bright magnetar and a few dozen extended Chandra sources within 15′ of the Galactic Center provide strong motivations to make use of the KaVA frequency band to search for pulsars in this region. Here, we describe the science targets and report progress made from the KVN test observations for known pulsars. We then discuss why KaVA pulsar observations are compelling
Photorefractive performances of a graphene-doped PATPD/7-DCST/ECZ composite
No full textRestricted Access.Photorefractive polymer composites have gained considerable attention due to their fascinating applications like 3D displays and 3D Telepresence. In this report, the performance of a novel PR polymer composite doped with graphene is studied. The addition of graphene laminates to a photorefractive composite results in up to threefold enhancement of space charge (SC) field build-up time. From our optical and electrical measurements, the faster build-up time is attributed to larger charge generation resulting from electronic interaction between graphene and the 7-DCST chromophores