111,866 research outputs found
Graphene and carbon black nano-composite polymer absorbers for a pyro-electric solar energy harvesting device based on LiNbO3 crystals
No full textA novel scheme for solar energy harvesting based on the pyro-electric effect has been demonstrated. The proposed harvester is based on an optical system focusing solar radiation onto a ferroelectric crystal (i.e. lithium niobate). The face exposed to the heating source is coated with a nanocomposite material (i.e. carbon black and graphene particles) that greatly improves the adsorption of solar radiation. The solar energy focused onto the crystal through a simple optical system allows one to induce a thermal gradient able to generate electric charges. Experiments have been carried out indoor as well as outdoor (in Pozzuoli, Naples, Italy, on December). Results show that two configurations appear to be preferable: (a) pyro-electric element with carbon black-based coating and a Fresnel lens (surface of about 100 cm(2)); (b) pyro-electric element with graphene-based coating and a Fresnel lens (surface of about 600 cm(2)). In both experimental arrangements the maximum temperature variation reached locally onto the lithium niobate substrate is relatively high with peaks greater than 250 degrees C. The maximum electrical power peak is of about 90 mu W and about 50 mu W for (a) and (b) respectively. The results of this first investigation are encouraging for further development of more efficient harvesting devices. (C) 2014 Elsevier Ltd. All rights reserved
One-step fabrication of free-standing flexible membranes reinforced with self-assembled arrays of carbon nanotubes
No full textOscillation Dynamics of Dielectric Polymer Droplets during Electrohydrodynamic Jetting in a Wide Range of Viscosities
No full text: The electrohydrodynamic (EHD) jetting of fluids is used for several applications such as inkjet printing, atomization of analyte in mass spectrometry, liquid metal alloy ion sources, and electrospinning of polymer fibers. Historically, the bulk of research has focused on nonviscous, highly conductive fluids which are most suitable for EHD spray and printing, while there is relatively little experimental work on EHD jetting of highly viscous liquid dielectrics. We studied the dynamics of oscillation and pulsating jetting from a suspended drop of polydimethylsiloxane (PDMS) polymers in an electric field, with particular attention to the viscosity dependence of the oscillation period and meniscus elongation and contraction time over a wide viscosity range (102-105 cSt). The reported results could help the appropriate design of EHD processes and may open new possibilities for the rheological characterization of liquid polymers using small volumes at the scale of nanoliters
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Drop-on-demand pyro-electrohydrodynamic printing of nematic liquid crystal microlenses
No full textInkjet printing of liquid crystal (LC) microlens arrays is particularly appealing for the development of switchable 2D/3D organic light-emitting diode (OLED) displays, as the printing process ensures that the lenses can be deposited directly and on-demand onto the pixelated OLED layer without the need for additional steps, thus simplifying fabrication complexity. Even if different fabrication technologies have been employed and good results in LC direct printing have already been achieved, all the systems used require costly equipment and heated nozzles to reduce the LC solution’s viscosity. Here, we present the direct printing of a nematic LC (NLC) lens by a Drop-on-Demand (DoD) inkjet printing by a pyro-electrohydrodynamic effect for the first time. The method works at ambient temperature and avoids dispensing nozzles, thus offering a noncontact manipulation approach of liquid with high resolution and good repeatability on different kinds of substrates. NLC microlenses are printed on different substrates and fully characterized. Polarization properties are evaluated for various samples, i.e., NLC lenses on unaligned and indium-tin oxide (ITO) aligned. Moreover, an in-depth characterization of the NLC lenses is reported by polarized optical microscopy and by analyzing the birefringence in digital holographic microscopy
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Hybrid ferroelectric-polymer microfluidic device for dielectrophoretic self-assembling of nanoparticles
No full textCarbon nanoparticles are becoming ubiquitous in many fields of science and technology. However, a grand challenge remains in assembling, patterning, and positioning or even simple manipulation of CNTs for complex functional assemblies. CNTs have in fact enormous perspectives for application in biotechnologies as bactericide agents or as prominent tools for investigating cell mechanisms, or more in general as functionalized nanoparticle-vectors, but their exploitation requires viable technology at the lab-on-a-chip scale. Many approaches have been attempted in developing technologies for manipulating CNTs. One elective approach is based on electric fields driven mechanisms such as DEP forces. A variety of chips have been designed and realized with this aim. Here we report on a novel hybrid microfluidic chip made by assembling a polar-dielectric crystal with polymeric microfluidic channels. One challenging feature of such a hybrid device approach, based on an electrode-free dielectrophoretic (DEP) approach, is that it makes use of surface charge templates for self-assembling and manipulation of CNTs in liquid media directly into a microfluidic channel. Here various examples of self-assembly in microfluidic channels as well as separation and collection of two classes of nano/microparticles are reported. The method can open the way to novel fabrication protocols for the realisation of future flexible devices with new and more complex functionalities, highly desirable in electronics as well as in biotechnology at the lab-on-a-chip scale. 2014 The Royal Society of Chemistry
QUICK LIQUID PACKAGING: EMBRACING WATER SILHOUETTES BY THREE-DIMENSIONAL POLYMER MEMBRANES
No full textVariations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Pyro-EHD ink-jet printing for direct functionalization of 3D lab-on-chip devices
No full textA challenging request in the fabrication of microfluidics and biomedical microsystems is a flexible ink-jet printing for breaking the rigidity of classical lithography. A pyroelectric-EHD system is presented. The system has proved challenging spatial resolution down to nanoscale, printing of high ordered patterns, capability of dispensing bio-ink as DNA and protein array for biosensing fabrication, single cells printing and direct printing of nanoparticles. With the method proposed high viscous polymers could be easily printed at high resolution in 2D or in 3D configuration. The pyro-EHD process has been proved for the fabrication of biodegradable microneedles for trasndermal drug delivery and 3D optical waveguides
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