Poincare ball embeddings of the optical geometry

International Nuclear Information System (INIS)

Abramowicz, M A; Bengtsson, I; Karas, V; Rosquist, K

2002-01-01

It is shown that the optical geometry of the Reissner-Nordstroem exterior metric can be embedded in a hyperbolic space all the way down to its outer horizon. The adopted embedding procedure removes a breakdown of flat-space embeddings which occurs outside the horizon, at and below the Buchdahl-Bondi limit (R/M=9/4 in the Schwarzschild case). In particular, the horizon can be captured in the optical geometry embedding diagram. Moreover, by using the compact Poincare ball representation of the hyperbolic space, the embedding diagram can cover the whole extent of radius from spatial infinity down to the horizon. Attention is drawn to the advantages of such embeddings in an appropriately curved space: this approach gives compact embeddings and it clearly distinguishes the case of an extremal black hole from a non-extremal one in terms of the topology of the embedded horizon

Embedded academic writing support for nursing students with English as a second language.

Science.gov (United States)

Salamonson, Yenna; Koch, Jane; Weaver, Roslyn; Everett, Bronwyn; Jackson, Debra

2010-02-01

This paper reports a study which evaluated a brief, embedded academic support workshop as a strategy for improving academic writing skills in first-year nursing students with low-to-medium English language proficiency. Nursing students who speak English as a second language have lower academic success compared with their native English-speaking counterparts. The development of academic writing skills is known to be most effective when embedded into discipline-specific curricula. Using a randomized controlled design, in 2008 106 students pre-enrolled in an introductory bioscience subject were randomized to receive either the intervention, a 4-day embedded academic learning support workshop facilitated by two bioscience (content) nursing academics and a writing and editing professional, or to act as the control group. The primary focus of the workshop was to support students to work through a mock assignment by providing progressive feedback and written suggestions on how to improve their answers. Of the 59 students randomized to the intervention, only 28 attended the workshop. Bioscience assignment results were analysed for those who attended (attendees), those randomized to the intervention but who did not attend (non-attendees), and the control group. Using anova, the results indicated that attendees achieved statistically significantly higher mean scores (70.8, sd: 6.1) compared to both control group (58.4, sd: 3.4, P = 0.002) and non-attendees (48.5, sd: 5.5, P = 0.001). A brief, intensive, embedded academic support workshop was effective in improving the academic writing ability of nursing students with low-to-medium English language proficiency, although reaching all students who are likely to benefit from this intervention remains a challenge.

Direct-write/cure conductive polymer nanocomposites for 3D structural electronics

Energy Technology Data Exchange (ETDEWEB)

Lu, Yanfeng; Vatani, Morteza; Choi, Jae Won [The University of Akron, Akron, Ohio (United States)

2013-10-15

The use of direct-write (DW) in the fabrication of conductive structures offers dramatic benefits over traditional technologies in terms of low-cost, print-on-demand conformal manufacturing. This DW process can be combined with direct-cure (DC) process as one-step manufacturing of conducting elements, whereas conventional methods need a manufacturing process of conducting elements followed by a relatively long time post-curing/baking process. A hybrid technology combined with direct-write/cure (DWC) and projection microstereolithography (PμSL) is presented in this work. Carbon nanotubes (CNTs) were dispersed in a photopolymer solution to introduce conductivity. The developed PμSL was used to create 3D structures, and DWC of conductive photopolymers with CNTs was utilized to produce conductive paths. To show the capabilities of the developed system and materials, a 3D structure with embedded conductive paths was designed and fabricated. Based on the experiments, it is thought that the suggested manufacturing process and materials are promising to produce 3D structural electronics.

Direct-write/cure conductive polymer nanocomposites for 3D structural electronics

International Nuclear Information System (INIS)

Lu, Yanfeng; Vatani, Morteza; Choi, Jae Won

2013-01-01

The use of direct-write (DW) in the fabrication of conductive structures offers dramatic benefits over traditional technologies in terms of low-cost, print-on-demand conformal manufacturing. This DW process can be combined with direct-cure (DC) process as one-step manufacturing of conducting elements, whereas conventional methods need a manufacturing process of conducting elements followed by a relatively long time post-curing/baking process. A hybrid technology combined with direct-write/cure (DWC) and projection microstereolithography (PμSL) is presented in this work. Carbon nanotubes (CNTs) were dispersed in a photopolymer solution to introduce conductivity. The developed PμSL was used to create 3D structures, and DWC of conductive photopolymers with CNTs was utilized to produce conductive paths. To show the capabilities of the developed system and materials, a 3D structure with embedded conductive paths was designed and fabricated. Based on the experiments, it is thought that the suggested manufacturing process and materials are promising to produce 3D structural electronics.

Laser direct writing using submicron-diameter fibers.

Science.gov (United States)

Tian, Feng; Yang, Guoguang; Bai, Jian; Xu, Jianfeng; Hou, Changlun; Liang, Yiyong; Wang, Kaiwei

2009-10-26

In this paper, a novel direct writing technique using submicron-diameter fibers is presented. The submicron-diameter fiber probe serves as a tightly confined point source and it adopts micro touch mode in the process of writing. The energy distribution of direct writing model is analyzed by Three-Dimension Finite-Difference Time-Domain method. Experiments demonstrate that submicron-diameter fiber direct writing has some advantages: simple process, 350-nm-resolution (lower than 442-nm-wavelength), large writing area, and controllable width of lines. In addition, by altering writing direction of lines, complex submicron patterns can be fabricated.

Direct femtosecond laser writing of buried infrared waveguides in chalcogenide glasses

Science.gov (United States)

Le Coq, D.; Bychkov, E.; Masselin, P.

2016-02-01

Direct laser writing technique is now widely used in particular in glass, to produce both passive and active photonic devices. This technique offers a real scientific opportunity to generate three-dimensional optical components and since chalcogenide glasses possess transparency properties from the visible up to mid-infrared range, they are of great interest. Moreover, they also have high optical non-linearity and high photo-sensitivity that make easy the inscription of refractive index modification. The understanding of the fundamental and physical processes induced by the laser pulses is the key to well-control the laser writing and consequently to realize integrated photonic devices. In this paper, we will focus on two different ways allowing infrared buried waveguide to be obtained. The first part will be devoted to a very original writing process based on a helical translation of the sample through the laser beam. In the second part, we will report on another original method based on both a filamentation phenomenon and a point by point technique. Finally, we will demonstrate that these two writing techniques are suitable for the design of single mode waveguide for wavelength ranging from the visible up to the infrared but also to fabricate optical components.

Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating.

Science.gov (United States)

Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

2014-07-31

Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure.

Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating

Science.gov (United States)

Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

2014-01-01

Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure. PMID:28788148

Cobalt nanoparticles deposited and embedded in AlN: Magnetic, magneto-optical, and morphological properties

International Nuclear Information System (INIS)

Huttel, Y.; Gomez, H.; Clavero, C.; Cebollada, A.; Armelles, G.; Navarro, E.; Ciria, M.; Benito, L.; Arnaudas, J.I.; Kellock, A.J.

2004-01-01

We present a structural, morphological, magnetic, and magneto-optical study of cobalt nanoparticles deposited on 50 A ring AlN/c-sapphire substrates and embedded in an AlN matrix. The dependence of the properties of Co nanoclusters deposited on AlN with growth temperature and amount of deposited Co are studied and discussed. Also we directly compare the properties of as grown and AlN embedded Co nanoclusters and show that the AlN matrix has a strong impact on their magnetic and magneto-optical properties

Engineering of refractive index in sulfide chalcogenide glass by direct laser writing

KAUST Repository

Zhang, Yaping; Gao, Yangqin; Ng, Tien Khee; Ooi, Boon S.; Chew, Basil; Hedhili, Mohamed N.; Zhao, Donghui; Jain, Himanshu

2010-01-01

Arsenic trisulfide (As2S3) glass is an interesting material for photonic integrated circuits (PICs) as infrared (IR) or nonlinear optical components. In this paper, direct laser writing was applied to engineer the refractive index of As2S3 thin film

Direct writing of metal nanostructures: lithographic tools for nanoplasmonics research.

Science.gov (United States)

Leggett, Graham J

2011-03-22

Continued progress in the fast-growing field of nanoplasmonics will require the development of new methods for the fabrication of metal nanostructures. Optical lithography provides a continually expanding tool box. Two-photon processes, as demonstrated by Shukla et al. (doi: 10.1021/nn103015g), enable the fabrication of gold nanostructures encapsulated in dielectric material in a simple, direct process and offer the prospect of three-dimensional fabrication. At higher resolution, scanning probe techniques enable nanoparticle particle placement by localized oxidation, and near-field sintering of nanoparticulate films enables direct writing of nanowires. Direct laser "printing" of single gold nanoparticles offers a remarkable capability for the controlled fabrication of model structures for fundamental studies, particle-by-particle. Optical methods continue to provide a powerful support for research into metamaterials.

Soil-embedded optical fiber sensing cable interrogated by Brillouin optical time-domain reflectometry (B-OTDR) and optical frequency-domain reflectometry (OFDR) for embedded cavity detection and sinkhole warning system

International Nuclear Information System (INIS)

Lanticq, V; Bourgeois, E; Delepine-Lesoille, S; Magnien, P; Dieleman, L; Vinceslas, G; Sang, A

2009-01-01

A soil-embedded optical fiber sensing cable is evaluated for an embedded cavity detection and sinkhole warning system in railway tunnels. Tests were performed on a decametric structure equipped with an embedded 110 m long fiber optic cable. Both Brillouin optical time-domain reflectometry (B-OTDR) and optical frequency-domain reflectometry (OFDR) sensing techniques were used for cable interrogation, yielding results that were in good qualitative agreement with finite-element calculations. Theoretical and experimental comparison enabled physical interpretation of the influence of ground properties, and the analysis of embedded cavity size and position. A 5 mm embedded cavity located 2 m away from the sensing cable was detected. The commercially available sensing cable remained intact after soil collapse. Specificities of each technique are analyzed in view of the application requirements. For tunnel monitoring, the OFDR technique was determined to be more viable than the B-OTDR due to higher spatial resolution, resulting in better detection and size determination of the embedded cavities. Conclusions of this investigation gave outlines for future field use of distributed strain-sensing methods under railways and more precisely enabled designing a warning system suited to the Ebersviller tunnel specificities

Polymeric flat focal field arrayed waveguide grating using electron-beam direct writing

Science.gov (United States)

Lu, Si; Yan, Yingbai; Jin, Guofan; Wong, W. H.; Pun, E. Y. B.

2004-06-01

A four-channel 400-GHz spacing flat focal field arrayed waveguide grating (AWG) demultiplexer is designed based on polymeric optical waveguide. The waveguide core-layer material is a newly developed negative tone epoxy Novolak resin (ENR) polymer with ultravoilet (UV) cured resin Norland optical adhesive 61 (NOA61) as the cladding layer. The device is fabricated using electron-beam direct writing, which has less processing steps than the reported polymeric AWGs. The experimental result is presented.

Dynamic temperature measurements with embedded optical sensors.

Energy Technology Data Exchange (ETDEWEB)

Dolan, Daniel H.,; Seagle, Christopher T; Ao, Tommy

2013-10-01

This report summarizes LDRD project number 151365, \\Dynamic Temperature Measurements with Embedded Optical Sensors". The purpose of this project was to develop an optical sensor capable of detecting modest temperature states (<1000 K) with nanosecond time resolution, a recurring diagnostic need in dynamic compression experiments at the Sandia Z machine. Gold sensors were selected because the visible re ectance spectrum of gold varies strongly with temperature. A variety of static and dynamic measurements were performed to assess re ectance changes at di erent temperatures and pressures. Using a minimal optical model for gold, a plausible connection between static calibrations and dynamic measurements was found. With re nements to the model and diagnostic upgrades, embedded gold sensors seem capable of detecting minor (<50 K) temperature changes under dynamic compression.

Directional Scattering of Semiconductor Nanoparticles Embedded in a Liquid Crystal

Directory of Open Access Journals (Sweden)

Braulio García-Cámara

2014-04-01

Full Text Available Light scattering by semiconductor nanoparticles has been shown to be more complex than was believed until now. Both electric and magnetic responses emerge in the visible range. In addition, directional effects on light scattering of these nanoparticles were recently obtained. In particular, zero backward and minimum-forward scattering are observed. These phenomena are very interesting for several applications such as, for instance, optical switches or modulators. The strong dependence of these phenomena on the properties of both the particle and the surrounding medium can be used to tune them. The electrical control on the optical properties of liquid crystals could be used to control the directional effects of embedded semiconductor nanoparticles. In this work, we theoretically analyze the effects on the directional distribution of light scattering by these particles when the refractive index of a surrounded liquid crystal changes from the ordinary to the extraordinary configuration. Several semiconductor materials and liquid crystals are studied in order to optimize the contrast between the two states.

DIRECT CORRECTIVE FEEDBACK ON STUDENTS‟WRITING PERFORMANCE

Directory of Open Access Journals (Sweden)

Testiana Deni Wijayatiningsih

2017-04-01

Full Text Available Teaching writing genre especially recount, narrative, and descriptive need brief and detail correction. Moreover, students aware about their mistakes in writing genre clearly. So, they can revise themselves. Based on the background above, this research aimed to know students‘achievement differences between using direct corrective feedback and indirect corrective feedback. The subject of this research was the fourth semester of English Department of Universitas Muhammadiyah Semarang. It employed quasi experiment and one group pre test post test design to analyze the students‘ writing achievement. The result showed that there is a significant differences between direct corrective feedback and indirect corrective feedback. Hopefully this research gives benefit for lecturers to use direct corrective feedback in their teaching writing process .

Radiative properties of optical board embedded with optical black holes

International Nuclear Information System (INIS)

Qiu, J.; Liu, L.H.; Hsu, P.-F.

2011-01-01

Unique radiative properties, such as wavelength-selective transmission or absorption, have been intensively studied. Historically, geometries for wavelength-selective of light absorption were developed based on metallic periodical structures, which were only applied in the case of TM wave incidence due to the excitation of surface plasmons. In this paper, we develop an alternative approach to selective wavelength of light absorption (both TE and TM waves), based on an optical board periodical embedded with optical black holes. Numerical work was carried out to study such structure's radiative properties within the wavelength range of 1-100 μm. The electromagnetic wave transmission through such a structure is predicted by solving Maxwell's equations using the finite-difference time-domain (FDTD) method. Spectral absorptance varies with the period of optical black holes. When the incidence wavelength is much larger than the inner core radius, most of the light energy will be transmitted through the inner core. Otherwise, the energy will be mainly absorbed. Numerical results of the radiative properties of the optical board with different incidence wavelengths are also obtained. The effect of the oblique incidence wave is investigated. This study helps us gain a better understanding of the radiative properties of an optical board embedded with optical black holes and develop an alternative approach to selective light absorption.

Evaluation of insertion characteristics of less invasive Si optoneural probe with embedded optical fiber

Science.gov (United States)

Morikawa, Takumi; Harashima, Takuya; Kino, Hisashi; Fukushima, Takafumi; Tanaka, Tetsu

2017-04-01

A less invasive Si optoneural probe with an embedded optical fiber was proposed and successfully fabricated. The diameter of the optical fiber was completely controlled by hydrogen fluoride etching, and the thinned optical fiber can propagate light without any leakage. This optical fiber was embedded in a trench formed inside a probe shank, which causes less damage to tissues. In addition, it was confirmed that the optical fiber embedded in the probe shank successfully irradiated light to optically stimulate gene transfected neurons. The electrochemical impedance of the probe did not change despite the light irradiation. Furthermore, probe insertion characteristics were evaluated in detail and less invasive insertion was clearly indicated for the Si optoneural probe with the embedded optical fiber compared with conventional optical neural probes. This neural probe with the embedded optical fiber can be used as a simple and easy tool for optogenetics and brain science.

Optical fiber sensors embedded in flexible polymer foils

Science.gov (United States)

van Hoe, Bram; van Steenberge, Geert; Bosman, Erwin; Missinne, Jeroen; Geernaert, Thomas; Berghmans, Francis; Webb, David; van Daele, Peter

2010-04-01

In traditional electrical sensing applications, multiplexing and interconnecting the different sensing elements is a major challenge. Recently, many optical alternatives have been investigated including optical fiber sensors of which the sensing elements consist of fiber Bragg gratings. Different sensing points can be integrated in one optical fiber solving the interconnection problem and avoiding any electromagnetical interference (EMI). Many new sensing applications also require flexible or stretchable sensing foils which can be attached to or wrapped around irregularly shaped objects such as robot fingers and car bumpers or which can even be applied in biomedical applications where a sensor is fixed on a human body. The use of these optical sensors however always implies the use of a light-source, detectors and electronic circuitry to be coupled and integrated with these sensors. The coupling of these fibers with these light sources and detectors is a critical packaging problem and as it is well-known the costs for packaging, especially with optoelectronic components and fiber alignment issues are huge. The end goal of this embedded sensor is to create a flexible optical sensor integrated with (opto)electronic modules and control circuitry. To obtain this flexibility, one can embed the optical sensors and the driving optoelectronics in a stretchable polymer host material. In this article different embedding techniques for optical fiber sensors are described and characterized. Initial tests based on standard manufacturing processes such as molding and laser structuring are reported as well as a more advanced embedding technique based on soft lithography processing.

Fabrication of multi-functional silicon surface by direct laser writing

Science.gov (United States)

Verma, Ashwani Kumar; Soni, R. K.

2018-05-01

We present a simple, quick and one-step methodology based on nano-second laser direct writing for the fabrication of micro-nanostructures on silicon surface. The fabricated surfaces suppress the optical reflection by multiple reflection due to light trapping effect to a much lower value than polished silicon surface. These textured surfaces offer high enhancement ability after gold nanoparticle deposition and then explored for Surface Enhanced Raman Scattering (SERS) for specific molecular detection. The effect of laser scanning line interval on optical reflection and SERS signal enhancement ability was also investigated. Our results indicate that low optical reflection substrates exhibit uniform SERS enhancement with enhancement factor of the order of 106. Furthermore, this methodology provide an alternative approach for cost-effective large area fabrication with good control over feature size.

Quasi-crystalline and disordered photonic structures fabricated using direct laser writing

Science.gov (United States)

Sinelnik, Artem D.; Pinegin, Konstantin V.; Bulashevich, Grigorii A.; Rybin, Mikhail V.; Limonov, Mikhail F.; Samusev, Kirill B.

2017-09-01

Direct laser writing is a rapid prototyping technology that has been utilized for the fabrication of micro- and nano-scale materials that have a perfect structure in most of the cases. In this study we exploit the direct laser writing to create several classes of non-periodic materials, such as quasi-crystalline lattices and three-dimensional (3D) objects with an orientation disorder in structural elements. Among quasi-crystalline lattices we consider Penrose tiling and Lévy-type photonic glasses. Images of the fabricated structures are obtained with a scanning electron microscope. In experiment we study the optical diffraction from 3D woodpile photonic structures with orientation disorder and analyze diffraction patters observed on a flat screen positioned behind the sample. With increasing of the disorder degree, we find an impressive transformation of the diffraction patterns from perfect Laue picture to a speckle pattern.

Interfacial characterization of soil-embedded optical fiber for ground deformation measurement

International Nuclear Information System (INIS)

Zhang, Cheng-Cheng; Zhu, Hong-Hu; Shi, Bin; She, Jun-Kuan

2014-01-01

Recently fiber-optic sensing technologies have been applied for performance monitoring of geotechnical structures such as slopes, foundations, and retaining walls. However, the validity of measured data from soil-embedded optical fibers is strongly influenced by the properties of the interface between the sensing fiber and the soil mass. This paper presents a study of the interfacial properties of an optical fiber embedded in soil with an emphasis on the effect of overburden pressure. Laboratory pullout tests were conducted to investigate the load-deformation characteristics of a 0.9 mm tight-buffered optical fiber embedded in soil. Based on a tri-linear interfacial shear stress-displacement relationship, an analytical model was derived to describe the progressive pullout behavior of an optical fiber from soil matrix. A comparison between the experimental and predicted results verified the effectiveness of the proposed pullout model. The test results are further interpreted and discussed. It is found that the interfacial bond between an optical fiber and soil is prominently enhanced under high overburden pressures. The apparent coefficients of friction of the optical fiber/soil interface decrease as the overburden pressure increases, due to the restrained soil dilation around the optical fiber. Furthermore, to facilitate the analysis of strain measurement, three working states of a soil-embedded sensing fiber were defined in terms of two characteristic displacements. (paper)

Additive direct-write microfabrication for MEMS: A review

Science.gov (United States)

Teh, Kwok Siong

2017-12-01

Direct-write additive manufacturing refers to a rich and growing repertoire of well-established fabrication techniques that builds solid objects directly from computer- generated solid models without elaborate intermediate fabrication steps. At the macroscale, direct-write techniques such as stereolithography, selective laser sintering, fused deposition modeling ink-jet printing, and laminated object manufacturing have significantly reduced concept-to-product lead time, enabled complex geometries, and importantly, has led to the renaissance in fabrication known as the maker movement. The technological premises of all direct-write additive manufacturing are identical—converting computer generated three-dimensional models into layers of two-dimensional planes or slices, which are then reconstructed sequentially into threedimensional solid objects in a layer-by-layer format. The key differences between the various additive manufacturing techniques are the means of creating the finished layers and the ancillary processes that accompany them. While still at its infancy, direct-write additive manufacturing techniques at the microscale have the potential to significantly lower the barrier-of-entry—in terms of cost, time and training—for the prototyping and fabrication of MEMS parts that have larger dimensions, high aspect ratios, and complex shapes. In recent years, significant advancements in materials chemistry, laser technology, heat and fluid modeling, and control systems have enabled additive manufacturing to achieve higher resolutions at the micrometer and nanometer length scales to be a viable technology for MEMS fabrication. Compared to traditional MEMS processes that rely heavily on expensive equipment and time-consuming steps, direct-write additive manufacturing techniques allow for rapid design-to-prototype realization by limiting or circumventing the need for cleanrooms, photolithography and extensive training. With current direct-write additive

Development of Blue Laser Direct-Write Lithography System

Directory of Open Access Journals (Sweden)

Hao-Wen Chang

2012-01-01

Full Text Available The optical lithography system researched in this study adopted the laser direct-write lithography technology with nano-positioning stage by using retailing blue ray optical pickup head contained 405nm wavelength and 0.85 numerical aperture of focus lens as the system lighting source. The system employed a photodiode received the focusing error signal reflected by the glass substrate to identify specimen position and automatic focused control with voice coil motor. The pattern substrate was loaded on a nano-positioning stage; input pattern path automatically and collocate with inner program at the same time. This research has successfully developed a blue laser lithography process system. The single spot size can be narrowed down to 3.07 μm and the linewidth is 3.3μm, time of laser control can reach to 450 ns and the exposure pattern can be controlled by program as well.

Laser-based direct-write techniques for cell printing

Energy Technology Data Exchange (ETDEWEB)

Schiele, Nathan R; Corr, David T [Biomedical Engineering Department, Rensselaer Polytechnic Institute, Troy, NY (United States); Huang Yong [Department of Mechanical Engineering, Clemson University, Clemson, SC (United States); Raof, Nurazhani Abdul; Xie Yubing [College of Nanoscale Science and Engineering, University at Albany, SUNY, Albany, NY (United States); Chrisey, Douglas B, E-mail: schien@rpi.ed, E-mail: chrisd@rpi.ed [Material Science and Engineering Department, Rensselaer Polytechnic Institute, Troy, NY (United States)

2010-09-15

Fabrication of cellular constructs with spatial control of cell location ({+-}5 {mu}m) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing. (topical review)

Laser-based direct-write techniques for cell printing

International Nuclear Information System (INIS)

Schiele, Nathan R; Corr, David T; Huang Yong; Raof, Nurazhani Abdul; Xie Yubing; Chrisey, Douglas B

2010-01-01

Fabrication of cellular constructs with spatial control of cell location (±5 μm) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing. (topical review)

Symmetrical waveguide devices fabricated by direct UV writing

DEFF Research Database (Denmark)

Færch, Kjartan Ullitz; Svalgaard, Mikael

2002-01-01

Power splitters and directional couplers fabricated by direct UV writing in index matched silica-on-silicon samples can suffer from an asymmetrical device performance, even though the UV writing is carried out in a symmetrical fashion. This effect originates from a reduced photosensitivity...

Direct-Dispense Polymeric Waveguides Platform for Optical Chemical Sensors

Directory of Open Access Journals (Sweden)

Mohamad Hajj-Hassan

2008-12-01

Full Text Available We describe an automated robotic technique called direct-dispense to fabricate a polymeric platform that supports optical sensor arrays. Direct-dispense, which is a type of the emerging direct-write microfabrication techniques, uses fugitive organic inks in combination with cross-linkable polymers to create microfluidic channels and other microstructures. Specifically, we describe an application of direct-dispensing to develop optical biochemical sensors by fabricating planar ridge waveguides that support sol-gelderived xerogel-based thin films. The xerogel-based sensor materials act as host media to house luminophore biochemical recognition elements. As a prototype implementation, we demonstrate gaseous oxygen (O2 responsive optical sensors that operate on the basis of monitoring luminescence intensity signals. The optical sensor employs a Light Emitting Diode (LED excitation source and a standard silicon photodiode as the detector. The sensor operates over the full scale (0%-100% of O2 concentrations with a response time of less than 1 second. This work has implications for the development of miniaturized multisensor platforms that can be cost-effectively and reliably mass-produced.

The passive optical properties of a silicon nanoparticle-embedded benzocyclobutene polymer waveguide

International Nuclear Information System (INIS)

Chiu, J.-J.; Perng, Tsong P

2008-01-01

The passive optical properties of a silicon nanoparticle-embedded benzocyclobutene (BCB) waveguide were investigated. The silicon nanoparticles, of a size varying from 6 to 25 nm, were prepared by vapor condensation. The transmission modes and losses were examined by the prism coupler and cut-back methods. A He-Ne laser beam with a wavelength of 6328 A was used to measure the effective index and thickness of the waveguide. Laser light could be efficiently coupled into the BCB waveguide when the embedded Si nanoparticles were smaller than 6 nm. The film thickness and effective index of the Si-embedded BCB waveguide were measured to be 1.825 μm and 1.565, respectively. The optical transmission losses of the pure BCB and Si-embedded ridge waveguides measured by the cut-back method were 0.85 and 1.63 dB cm -1 , respectively. Although the optical loss was increased by the embedded Si, the disturbance of the output contour was quite small. This result demonstrates that the nanoparticle-embedded polymer waveguide may be used for optoelectronic integrated circuits

How directional change in reading/writing habits relates to directional change in displayed pictures.

Science.gov (United States)

Lee, Hachoung; Oh, Songjoo

2016-01-01

It has been suggested that reading/writing habits may influence the appreciation of pictures. For example, people who read and write in a rightward direction have an aesthetic preference for pictures that face rightward over pictures that face leftward, and vice versa. However, correlations for this phenomenon have only been found in cross-cultural studies. Will a directional change in reading/writing habits within a culture relate to changes in picture preference? Korea is a good place to research this question because the country underwent gradual changes in reading/writing direction habits, from leftward to rightward, during the 20th century. In this study, we analyzed the direction of drawings and photos published in the two oldest newspapers in Korea from 1920-2013. The results show that the direction of the drawings underwent a clear shift from the left to the right, but the direction of the photos did not change. This finding suggests a close psychological link between the habits of reading/writing and drawing that cannot be accounted for simply by an accidental correspondence across different cultures.

Laser direct writing of micro- and nano-scale medical devices

Science.gov (United States)

Gittard, Shaun D; Narayan, Roger J

2010-01-01

Laser-based direct writing of materials has undergone significant development in recent years. The ability to modify a variety of materials at small length scales and using short production times provides laser direct writing with unique capabilities for fabrication of medical devices. In many laser-based rapid prototyping methods, microscale and submicroscale structuring of materials is controlled by computer-generated models. Various laser-based direct write methods, including selective laser sintering/melting, laser machining, matrix-assisted pulsed-laser evaporation direct write, stereolithography and two-photon polymerization, are described. Their use in fabrication of microstructured and nanostructured medical devices is discussed. Laser direct writing may be used for processing a wide variety of advanced medical devices, including patient-specific prostheses, drug delivery devices, biosensors, stents and tissue-engineering scaffolds. PMID:20420557

A new repeatable, optical writing and electrical erasing device based on photochromism and electrochromism of viologen

International Nuclear Information System (INIS)

Gao, Li-ping; Wei, Jian; Wang, Yue-chuan; Ding, Guo-jing; Yang, Yu-lin

2012-01-01

New optical writing and electrical erasing devices have been successfully fabricated that exploit the photochromism and electrochromism of viologen. In a preliminary study, both the structures of viologen and device were investigated in detail by UV–vis spectra in order to confirm their effects on the optical writing and electrical erasing performances of corresponding devices. For sandwiched, single and complementary devices based on benzyl viologen (BV 2+ ), only optical writing can be performed, not electrical erasing operations, which indicated these devices cannot realize optical information rewriting. For single and complementary devices based on styrene-functional viologen (V BV 2+ ) and acrylic-functional viologen (ACV 2+ ), optical writing and electrical erasing operations can be reversibly performed and optical information rewriting realized. It is clear that single devices based on V BV 2+ and ACV 2+ possess better performance accompanied with contrast without significant degradation and bleaching times and without significant deterioration over 10 repeated writing/erasing cycles. Furthermore, we put forward possible mechanisms for sandwiched, single and complementary devices based on V BV 2+ and ACV 2+ for the optical writing and electrical erasing operations. This study provides a new strategy to design optical writing and electrical erasing devices to realize optical information rewriting. (paper)

Direct UV-Written Integrated Optical Beam Combiner for Stellar Interferometry

DEFF Research Database (Denmark)

Olivero, Massimo; Svalgaard, Mikael; Jocou, L.

2007-01-01

In this paper, we report the fabrication of an optical-beam combiner for stellar interferometry by means of direct ultraviolet (UV) writing. The component is shown to have good performance (fringe contrast > 95%, total loss similar to 0.7, -40-dB crosstalk, broadband operation covering at least...... the range 1.49-1.65 mu m, and low differential chromatic dispersion). The overall performance exceeds that of similar components currently used for astronomical research. This result, combined with the fast-prototyping ability of UV writing, opens up new possibilities for the realization of highly optimized...

Direct Writing of Three-Dimensional Macroporous Photonic Crystals on Pressure-Responsive Shape Memory Polymers.

Science.gov (United States)

Fang, Yin; Ni, Yongliang; Leo, Sin-Yen; Wang, Bingchen; Basile, Vito; Taylor, Curtis; Jiang, Peng

2015-10-28

Here we report a single-step direct writing technology for making three-dimensional (3D) macroporous photonic crystal patterns on a new type of pressure-responsive shape memory polymer (SMP). This approach integrates two disparate fields that do not typically intersect: the well-established templating nanofabrication and shape memory materials. Periodic arrays of polymer macropores templated from self-assembled colloidal crystals are squeezed into disordered arrays in an unusual shape memory "cold" programming process. The recovery of the original macroporous photonic crystal lattices can be triggered by direct writing at ambient conditions using both macroscopic and nanoscopic tools, like a pencil or a nanoindenter. Interestingly, this shape memory disorder-order transition is reversible and the photonic crystal patterns can be erased and regenerated hundreds of times, promising the making of reconfigurable/rewritable nanooptical devices. Quantitative insights into the shape memory recovery of collapsed macropores induced by the lateral shear stresses in direct writing are gained through fundamental investigations on important process parameters, including the tip material, the critical pressure and writing speed for triggering the recovery of the deformed macropores, and the minimal feature size that can be directly written on the SMP membranes. Besides straightforward applications in photonic crystal devices, these smart mechanochromic SMPs that are sensitive to various mechanical stresses could render important technological applications ranging from chromogenic stress and impact sensors to rewritable high-density optical data storage media.

UV waveguides light fabricated in fluoropolymer CYTOP by femtosecond laser direct writing.

Science.gov (United States)

Hanada, Yasutaka; Sugioka, Koji; Midorikawa, Katsumi

2010-01-18

We have fabricated optical waveguides inside the UV-transparent polymer, CYTOP, by femtosecond laser direct writing for propagating UV light in biochip applications. Femtosecond laser irradiation is estimated to increase the refractive index of CYTOP by 1.7 x 10(-3) due to partial bond breaking in CYTOP. The waveguide in CYTOP has propagation losses of 0.49, 0.77, and 0.91 dB/cm at wavelengths of 632.8, 355, and 266 nm, respectively.

Direct Embedding of Fiber-Optical Load Sensors into Wind Turbine Blades

DEFF Research Database (Denmark)

Glavind, Lars; Buggy, Stephen; Olesen, Ib S.

Long Period Gratings were embedded into the adhesive utilized in the matrix of a wind turbine blade. The LPGs were subsequently subjected to temperature-testing in order to assess their performance, which illustrates good embedding capabilities....

Reducing Unintentional Plagiarism amongst International Students in the Biological Sciences: An Embedded Academic Writing Development Programme

Science.gov (United States)

Divan, Aysha; Bowman, Marion; Seabourne, Anna

2015-01-01

There is general agreement in the literature that international students are more likely to plagiarise compared to their native speaker peers and, in many instances, plagiarism is unintentional. In this article we describe the effectiveness of an academic writing development programme embedded into a Biological Sciences Taught Masters course…

Design of titania nanotube structures by focused laser beam direct writing

International Nuclear Information System (INIS)

Enachi, Mihai; Stevens-Kalceff, Marion A.; Sarua, Andrei; Ursaki, Veaceslav; Tiginyanu, Ion

2013-01-01

In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO 2 NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes

Integrated Optical Interconnect Architectures for Embedded Systems

CERN Document Server

Nicolescu, Gabriela

2013-01-01

This book provides a broad overview of current research in optical interconnect technologies and architectures. Introductory chapters on high-performance computing and the associated issues in conventional interconnect architectures, and on the fundamental building blocks for integrated optical interconnect, provide the foundations for the bulk of the book which brings together leading experts in the field of optical interconnect architectures for data communication. Particular emphasis is given to the ways in which the photonic components are assembled into architectures to address the needs of data-intensive on-chip communication, and to the performance evaluation of such architectures for specific applications.   Provides state-of-the-art research on the use of optical interconnects in Embedded Systems; Begins with coverage of the basics for high-performance computing and optical interconnect; Includes a variety of on-chip optical communication topologies; Features coverage of system integration and opti...

Direct-write maskless lithography using patterned oxidation of Si-substrate Induced by femtosecond laser pulses

Science.gov (United States)

Kiani, Amirkianoosh; Venkatakrishnan, Krishnan; Tan, Bo

2013-03-01

In this study we report a new method for direct-write maskless lithography using oxidized silicon layer induced by high repetition (MHz) ultrafast (femtosecond) laser pulses under ambient condition. The induced thin layer of predetermined pattern can act as an etch stop during etching process in alkaline etchants such as KOH. The proposed method can be leading to promising solutions for direct-write maskless lithography technique since the proposed method offers a higher degree of flexibility and reduced time and cost of fabrication which makes it particularly appropriate for rapid prototyping and custom scale manufacturing. A Scanning Electron Microscope (SEM), Micro-Raman, Energy Dispersive X-ray (EDX), optical microscope and X-ray diffraction spectroscopy (XRD) were used to evaluate the quality of oxidized layer induced by laser pulses.

Embedded calibration system for the DIII-D Langmuir probe analog fiber optic links

International Nuclear Information System (INIS)

Watkins, J. G.; Rajpal, R.; Mandaliya, H.; Watkins, M.; Boivin, R. L.

2012-01-01

This paper describes a generally applicable technique for simultaneously measuring offset and gain of 64 analog fiber optic data links used for the DIII-D fixed Langmuir probes by embedding a reference voltage waveform in the optical transmitted signal before every tokamak shot. The calibrated data channels allow calibration of the power supply control fiber optic links as well. The array of fiber optic links and the embedded calibration system described here makes possible the use of superior modern data acquisition electronics in the control room.

Polymeric turbidity sensor fabricated by laser direct writing

International Nuclear Information System (INIS)

Li, Shu; Lin, Qiao; Wu, George; Chen, Liuhua; Wu, X

2011-01-01

The design of a miniature-sized turbidity sensor fabricated by laser direct writing was proposed and tested. A dual-beam dual-detector sensing structure was written by a 488 nm laser from UV curable optical polymer to form a 4 mm diameter turbidity sensing probe, with the fabrication process being shortened to a few seconds. Experimental tests on prototypes were conducted by using standard turbidity solutions, and the data were processed with a self-adapting neural network based on a single input single output algorithm. The scattering coefficient for normalized turbidity of the standards was obtained, and system accuracy was validated by an error analysis. Experimental results indicated that in the testing situation presented in this paper, the sensor was capable of responding to turbidity with a relative error of about 3%

Direct UV-writing of waveguides

DEFF Research Database (Denmark)

Færch, Kjartan Ullitz

2003-01-01

induced refractive index change of more than 10-2 have been obtained. New insight, with respect to understanding the UV induced index change obtained by direct UV writing, has been provided, through experiments conducted with such high-pressure loaded germanosilica samples. This include measurements...

Carbon nanotube formation by laser direct writing

International Nuclear Information System (INIS)

Wu, Y.-T.; Su, H.-C.; Tsai, C.-M.; Liu, K.-L.; Chen, G.-D.; Huang, R.-H.; Yew, T.-R.

2008-01-01

This letter presents carbon nanotube (CNT) formation by laser direct writing using 248 nm KrF excimer pulsed laser in air at room temperature, which was applied to irradiate amorphous carbon (a-C) assisted by Ni catalysts underneath for the transformation of carbon species into CNTs. The CNTs were synthesized under appropriate combination of laser energy density and a-C thickness. The growth mechanism and key parameters to determine the success of CNT formation were also discussed. The demonstration of the CNT growth by laser direct writing in air at room temperature opens an opportunity of in-position CNT formation at low temperatures

Dynamic virtual optical network embedding in spectral and spatial domains over elastic optical networks with multicore fibers

Science.gov (United States)

Zhu, Ruijie; Zhao, Yongli; Yang, Hui; Tan, Yuanlong; Chen, Haoran; Zhang, Jie; Jue, Jason P.

2016-08-01

Network virtualization can eradicate the ossification of the infrastructure and stimulate innovation of new network architectures and applications. Elastic optical networks (EONs) are ideal substrate networks for provisioning flexible virtual optical network (VON) services. However, as network traffic continues to increase exponentially, the capacity of EONs will reach the physical limitation soon. To further increase network flexibility and capacity, the concept of EONs is extended into the spatial domain. How to map the VON onto substrate networks by thoroughly using the spectral and spatial resources is extremely important. This process is called VON embedding (VONE).Considering the two kinds of resources at the same time during the embedding process, we propose two VONE algorithms, the adjacent link embedding algorithm (ALEA) and the remote link embedding algorithm (RLEA). First, we introduce a model to solve the VONE problem. Then we design the embedding ability measurement of network elements. Based on the network elements' embedding ability, two VONE algorithms were proposed. Simulation results show that the proposed VONE algorithms could achieve better performance than the baseline algorithm in terms of blocking probability and revenue-to-cost ratio.

Ultra-Low Power Optical Transistor Using a Single Quantum Dot Embedded in a Photonic Wire

DEFF Research Database (Denmark)

Nguyen, H.A.; Grange, T.; Malik, N.S.

2017-01-01

Using a single InAs quantum dot embedded in a GaAs photonic wire, we realize a giant non-linearity between two optical modes to experimentally demonstrate an all-optical transistor triggered by 10 photons.......Using a single InAs quantum dot embedded in a GaAs photonic wire, we realize a giant non-linearity between two optical modes to experimentally demonstrate an all-optical transistor triggered by 10 photons....

Creating large second-order optical nonlinearity in optical waveguides written by femtosecond laser pulses in boro-aluminosilicate glass

Science.gov (United States)

An, Hong-Lin; Arriola, Alexander; Gross, Simon; Fuerbach, Alexander; Withford, Michael J.; Fleming, Simon

2014-01-01

The thermal poling technique was applied to optical waveguides embedded in a commercial boro-aluminosilicate glass, resulting in high levels of induced second-order optical nonlinearity. The waveguides were fabricated using the femtosecond laser direct-write technique, and thermally poled samples were characterized with second harmonic optical microscopy to reveal the distribution profile of the induced nonlinearity. It was found that, in contrast to fused silica, the presence of waveguides in boro-aluminosilicate glass led to an enhancement of the creation of the second-order nonlinearity, which is larger in the laser written waveguiding regions when compared to the un-modified substrate. The magnitude of the nonlinear coefficient d33 achieved in the core of the laser-written waveguides, up to 0.2 pm/V, was comparable to that in thermally poled fused silica, enabling the realization of compact integrated electro-optic devices in boro-aluminosilicate glasses.

Embedded Bragg grating fiber optic sensor for composite flexbeams

Science.gov (United States)

Bullock, Daniel; Dunphy, James; Hufstetler, Gerard

1993-03-01

An embedded fiber-optic (F-O) sensor has been developed for translaminar monitoring of the structural integrity of composites, with a view to application in composite helicopter flexbeams for bearingless main rotor hubs. This through-thickness strain sensor is much more sensitive than conventional in-plane embedded F-O sensors to ply delamination, on the basis of a novel insertion technique and innovative Bragg grating sensor. Experimental trials have demonstrated the detection by this means of potential failures in advance of the edge-delamination or crack-propagation effect.

Novel silica surface charge density mediated control of the optical properties of embedded optically active materials and its application for fiber optic pH sensing at elevated temperatures.

Science.gov (United States)

Wang, Congjun; Ohodnicki, Paul R; Su, Xin; Keller, Murphy; Brown, Thomas D; Baltrus, John P

2015-02-14

Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices.

Imaging spectroscopy using embedded diffractive optical arrays

Science.gov (United States)

Hinnrichs, Michele; Hinnrichs, Bradford

2017-09-01

Pacific Advanced Technology (PAT) has developed an infrared hyperspectral camera based on diffractive optic arrays. This approach to hyperspectral imaging has been demonstrated in all three infrared bands SWIR, MWIR and LWIR. The hyperspectral optical system has been integrated into the cold-shield of the sensor enabling the small size and weight of this infrared hyperspectral sensor. This new and innovative approach to an infrared hyperspectral imaging spectrometer uses micro-optics that are made up of an area array of diffractive optical elements where each element is tuned to image a different spectral region on a common focal plane array. The lenslet array is embedded in the cold-shield of the sensor and actuated with a miniature piezo-electric motor. This approach enables rapid infrared spectral imaging with multiple spectral images collected and processed simultaneously each frame of the camera. This paper will present our optical mechanical design approach which results in an infrared hyper-spectral imaging system that is small enough for a payload on a small satellite, mini-UAV, commercial quadcopter or man portable. Also, an application of how this spectral imaging technology can easily be used to quantify the mass and volume flow rates of hydrocarbon gases. The diffractive optical elements used in the lenslet array are blazed gratings where each lenslet is tuned for a different spectral bandpass. The lenslets are configured in an area array placed a few millimeters above the focal plane and embedded in the cold-shield to reduce the background signal normally associated with the optics. The detector array is divided into sub-images covered by each lenslet. We have developed various systems using a different number of lenslets in the area array. Depending on the size of the focal plane and the diameter of the lenslet array will determine the number of simultaneous different spectral images collected each frame of the camera. A 2 x 2 lenslet array will image

Electrohydrodynamic Direct-Write Orderly Micro/Nanofibrous Structure on Flexible Insulating Substrate

Directory of Open Access Journals (Sweden)

Jiang-Yi Zheng

2014-01-01

Full Text Available AC pulse-modulated electrohydrodynamic direct-writing (EDW was utilized to direct-write orderly micro/nanofibrous structure on the flexible insulating polyethylene terephthalate (PET substrate. During the EDW process, AC electrical field induced charges to reciprocate along the jet and decreased the charge repulsive force that applied on charged jet. Thanks to the smaller charge repulsive force, stable straight jet can be built up to direct-write orderly micro/nanofibrous structures on the insulating substrate. The minimum motion velocity required to direct-write straight line fibrous structure on insulating PET substrate was 700 mm/s. Moreover, the influences of AC voltage amplitude, frequency, and duty cycle ratio on the line width of fibrous structures were investigated. This work proposes a novel solution to overcome the inherent charge repulsion emerging on the insulating substrate, and promotes the application of EDW technology on the flexible electronics.

Effect of D2 outdiffusion on direct writing of optical waveguides

DEFF Research Database (Denmark)

Svalgaard, Mikael

1999-01-01

It is shown that the performance of UV written waveguides can be influenced strongly by the outdiffusion of molecular deuterium during fabrication. By cooling the sample to -33 °C, the time available for UV writing may be increased to > 10 h, compared to ~15 min at room temperature.......It is shown that the performance of UV written waveguides can be influenced strongly by the outdiffusion of molecular deuterium during fabrication. By cooling the sample to -33 °C, the time available for UV writing may be increased to > 10 h, compared to ~15 min at room temperature....

Updated optical read/write memory system components

Science.gov (United States)

1974-01-01

A survey of the building blocks of the electro-optic read/write system was made. Critical areas and alternate paths are discussed. The latest PLZT block data composer is analyzed. Stricter controls in the production and fabrication of PLZT are implied by the performance of the BDC. A reverse charge before erase has eliminated several problems observed in the parallel plane charging process for photoconductor-thermoplastic hologram storage.

5 nm structures produced by direct laser writing

International Nuclear Information System (INIS)

Pavel, E; Jinga, S; Andronescu, E; Vasile, B S; Rotiu, E; Ionescu, L; Mazilu, C

2011-01-01

Here we present a new approach to overcome the optical diffraction limit by using novel materials. In the paper, we report experimental results obtained by high-resolution transmission electron microscopy (HRTEM) and optical absorption spectroscopy, for a fluorescent photosensitive glass-ceramic containing rare-earth ions such as samarium (Sm). Using a home built dynamic tester, with a low power laser, we recorded nanostructures having 5 nm line widths. In the line structure, measurements reveal the presence of silver nanocrystals with few nanometre sizes. HRTEM shows that there is a random orientation of the nanocrystals. A writing mechanism with three steps is proposed.

Optical properties of metal nanoparticles embedded in amorphous silicon analysed using discrete dipole approximation

Science.gov (United States)

Fantoni, Alessandro; Fernandes, Miguel; Vygranenko, Yuri; Vieira, Manuela; Oliveira-Silva, Rui P.; Prazeres, D. M. F.; Ribeiro, Ana P. C.; Alegria, Elisabete C. B. A.

2018-02-01

Localized surface plasmons (LSP) can be excited in metal nanoparticles (NP) by UV, visible or NIR light and are described as coherent oscillation of conduction electrons. Taking advantage of the tunable optical properties of NPs, we propose the realization of a plasmonic structure, based on the LSP interaction of NP with an embedding matrix of amorphous silicon. This study is directed to define the characteristics of NP and substrate necessary to the development of a LSP proteomics sensor that, once provided immobilized antibodies on its surface, will screen the concentration of selected antigens through the determination of LSPR spectra and peaks of light absorption. Metals of interest for NP composition are: Aluminium and Gold. Recent advances in nanoparticle production techniques allow almost full control over shapes and size, permitting full control over their optical and plasmonic properties and, above all, over their responsive spectra. Analytical solution is only possible for simple NP geometries, therefore our analysis, is realized recurring to computer simulation using the Discrete Dipole Approximation method (DDA). In this work we use the free software DDSCAT to study the optical properties of metal nanoparticles embedded in an amorphous silicon matrix, as a function of size, shape, aspect-ratio and metal type. Experimental measurements realized with arrays of metal nanoparticles are compared with the simulations.

Bragg grating writing in PMMA microstructured polymer optical fibers in less than 7 minutes

DEFF Research Database (Denmark)

Bundalo, Ivan-Lazar; Nielsen, Kristian; Markos, Christos

2014-01-01

We demonstrate fiber Bragg grating (FBG) writing in PMMA microstructured Polymer Optical Fibers (mPOFs) using UV Phase Mask technique with writing times shorter than 10 min. The shortest writing time was 6 minutes and 50 seconds and the longest writing time was 8 min and 50 sec. The FBGs were...... written in a 125 x00B5;m PMMA mPOF having 3-rings of holes, the reflection peaks were centred at 632.6 nm and have a reflectivity as high as 26 dB. We also demonstrate how the writing dynamics depends on the intensity of the writing beam....

Simultaneous measurement of temperature and tensile loading using superstructure FBGs developed by laser direct writing of periodic on-fiber metallic films

International Nuclear Information System (INIS)

Alemohammad, Hamidreza; Toyserkani, Ehsan

2009-01-01

This paper addresses the development of superstructure fiber Bragg gratings (FBGs) by laser-assisted direct writing of on-fiber metallic films. A novel laser direct write method is characterized to fabricate periodic films of silver nanoparticles on the non-planar surface of as-fabricated FBGs. Silver films with a thickness of 9 µm are fabricated around a Bragg grating optical fiber. The performance of the superstructure FBG is studied by applying temperature and tensile stress on the fiber. An opto-mechanical model is also developed to predict the optical response of the synthesized superstructure FBG under thermal and structural loadings. The results show that the reflectivity of sidebands in the reflection spectrum can be tuned up to 20% and 37% under thermal and structural loadings, respectively. In addition, the developed superstructure FBG is used for simultaneous measurement of force and temperature to eliminate the inherent limitation of regular FBGs in multi-parameter sensing

Effect of Direct Grammar Instruction on Student Writing Skills

Science.gov (United States)

Robinson, Lisa; Feng, Jay

2016-01-01

Grammar Instruction has an important role to play in helping students to speak and write more effectively. The purpose of this study was to examine the effects of direct grammar instruction on the quality of student's writing skills. The participants in this study included 18 fifth grade students and two fifth grade teachers. Based on the results…

Fluorescent Nanocomposite of Embedded Ceria Nanoparticles in Crosslinked PVA Electrospun Nanofibers

Directory of Open Access Journals (Sweden)

Nader Shehata

2016-06-01

Full Text Available This paper introduces a new fluorescent nanocomposite of electrospun biodegradable nanofibers embedded with optical nanoparticles. In detail, this work introduces the fluorescence properties of PVA nanofibers generated by the electrospinning technique with embedded cerium oxide (ceria nanoparticles. Under near-ultra violet excitation, the synthesized nanocomposite generates a visible fluorescent emission at 520 nm, varying its intensity peak according to the concentration of in situ embedded ceria nanoparticles. This is due to the fact that the embedded ceria nanoparticles have optical tri-valiant cerium ions, associated with formed oxygen vacancies, with a direct allowed bandgap around 3.5 eV. In addition, the impact of chemical crosslinking of the PVA on the fluorescence emission is studied in both cases of adding ceria nanoparticles in situ or of a post-synthesis addition via a spin-coating mechanism. Other optical and structural characteristics such as absorbance dispersion, direct bandgap, FTIR spectroscopy, and SEM analysis are presented. The synthesized optical nanocomposite could be helpful in different applications such as environmental monitoring and bioimaging.

Fast and Scalable Fabrication of Microscopic Optical Surfaces and its Application for Optical Interconnect Devices

Science.gov (United States)

Summitt, Christopher Ryan

The use of optical interconnects is a promising solution to the increasing demand for high speed mass data transmission used in integrated circuits as well as device to device data transfer applications. For the purpose, low cost polymer waveguides are a popular choice for routing signal between devices due to their compatibility with printed circuit boards. In optical interconnect, coupling from an external light source to such waveguides is a critical step, thus a variety of couplers have been investigated such as grating based couplers [1,2], evanescent couplers [3], and embedded mirrors [4-6]. These couplers are inherently micro-optical components which require fast and scalable fabrication for mass production with optical quality surfaces/structures. Low NA laser direct writing has been used for fast fabrication of structures such as gratings and Fresnel lenses using a linear laser direct writing scheme, though the length scale of such structures are an order of magnitude larger than the spot size of the focused laser of the tool. Nonlinear writing techniques such as with 2-photon absorption offer increased write resolution which makes it possible to fabricate sub-wavelength structures as well as having a flexibility in feature shape. However it does not allow a high speed fabrication and in general are not scalable due to limitations of speed and area induced by the tool's high NA optics. To overcome such limitations primarily imposed by NA, we propose a new micro-optic fabrication process which extends the capabilities of 1D, low NA, and thus fast and scalable, laser direct writing to fabricate a structure having a length scale close to the tool's spot size, for example, a mirror based and 45 degree optical coupler with optical surface quality. The newly developed process allows a high speed fabrication with a write speed of 2600 mm²/min by incorporating a mask based lithography method providing a blank structure which is critical to creating a 45 degree

Structural and optical properties of germanium nanostructures on Si(100 and embedded in high-k oxides

Directory of Open Access Journals (Sweden)

Ray Samit

2011-01-01

Full Text Available Abstract The structural and optical properties of Ge quantum dots (QDs grown on Si(001 for mid-infrared photodetector and Ge nanocrystals embedded in oxide matrices for floating gate memory devices are presented. The infrared photoluminescence (PL signal from Ge islands has been studied at a low temperature. The temperature- and bias-dependent photocurrent spectra of a capped Si/SiGe/Si(001 QDs infrared photodetector device are presented. The properties of Ge nanocrystals of different size and density embedded in high-k matrices grown using radio frequency magnetron sputtering have been studied. Transmission electron micrographs have revealed the formation of isolated spherical Ge nanocrystals in high-k oxide matrix of sizes ranging from 4 to 18 nm. Embedded nanocrystals in high band gap oxides have been found to act as discrete trapping sites for exchanging charge carriers with the conduction channel by direct tunneling that is desired for applications in floating gate memory devices.

Femtosecond laser direct writing of monocrystalline hexagonal silver prisms

Energy Technology Data Exchange (ETDEWEB)

Vora, Kevin; Kang, SeungYeon; Moebius, Michael [School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138 (United States); Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138 (United States); Department of Physics, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138 (United States)

2014-10-06

Bottom-up growth methods and top-down patterning techniques are both used to fabricate metal nanostructures, each with a distinct advantage: One creates crystalline structures and the other offers precise positioning. Here, we present a technique that localizes the growth of metal crystals to the focal volume of a laser beam, combining advantages from both approaches. We report the fabrication of silver nanoprisms—hexagonal nanoscale silver crystals—through irradiation with focused femtosecond laser pulses. The growth of these nanoprisms is due to a nonlinear optical interaction between femtosecond laser pulses and a polyvinylpyrrolidone film doped with silver nitrate. The hexagonal nanoprisms have bases hundreds of nanometers in size and the crystal growth occurs over exposure times of less than 1 ms (8 orders of magnitude faster than traditional chemical techniques). Electron backscatter diffraction analysis shows that the hexagonal nanoprisms are monocrystalline. The fabrication method combines advantages from both wet chemistry and femtosecond laser direct-writing to grow silver crystals in targeted locations. The results presented in this letter offer an approach to directly positioning and growing silver crystals on a substrate, which can be used for plasmonic devices.

Femtosecond laser direct writing of monocrystalline hexagonal silver prisms

International Nuclear Information System (INIS)

Vora, Kevin; Kang, SeungYeon; Moebius, Michael; Mazur, Eric

2014-01-01

Bottom-up growth methods and top-down patterning techniques are both used to fabricate metal nanostructures, each with a distinct advantage: One creates crystalline structures and the other offers precise positioning. Here, we present a technique that localizes the growth of metal crystals to the focal volume of a laser beam, combining advantages from both approaches. We report the fabrication of silver nanoprisms—hexagonal nanoscale silver crystals—through irradiation with focused femtosecond laser pulses. The growth of these nanoprisms is due to a nonlinear optical interaction between femtosecond laser pulses and a polyvinylpyrrolidone film doped with silver nitrate. The hexagonal nanoprisms have bases hundreds of nanometers in size and the crystal growth occurs over exposure times of less than 1 ms (8 orders of magnitude faster than traditional chemical techniques). Electron backscatter diffraction analysis shows that the hexagonal nanoprisms are monocrystalline. The fabrication method combines advantages from both wet chemistry and femtosecond laser direct-writing to grow silver crystals in targeted locations. The results presented in this letter offer an approach to directly positioning and growing silver crystals on a substrate, which can be used for plasmonic devices.

Optical architecture design for detection of absorbers embedded in visceral fat.

Science.gov (United States)

Francis, Robert; Florence, James; MacFarlane, Duncan

2014-05-01

Optically absorbing ducts embedded in scattering adipose tissue can be injured during laparoscopic surgery. Non-sequential simulations and theoretical analysis compare optical system configurations for detecting these absorbers. For absorbers in deep scattering volumes, trans-illumination is preferred instead of diffuse reflectance. For improved contrast, a scanning source with a large area detector is preferred instead of a large area source with a pixelated detector.

3D direct writing fabrication of electrodes for electrochemical storage devices

Science.gov (United States)

Wei, Min; Zhang, Feng; Wang, Wei; Alexandridis, Paschalis; Zhou, Chi; Wu, Gang

2017-06-01

Among different printing techniques, direct ink writing is commonly used to fabricate 3D battery and supercapacitor electrodes. The major advantages of using the direct ink writing include effectively building 3D structure for energy storage devices and providing higher power density and higher energy density than traditional techniques due to the increased surface area of electrode. Nevertheless, direct ink writing has high standards for the printing inks, which requires high viscosity, high yield stress under shear and compression, and well-controlled viscoelasticity. Recently, a number of 3D-printed energy storage devices have been reported, and it is very important to understand the printing process and the ink preparation process for further material design and technology development. We discussed current progress of direct ink writing technologies by using various electrode materials including carbon nanotube-based material, graphene-based material, LTO (Li4Ti5O12), LFP (LiFePO4), LiMn1-xFexPO4, and Zn-based metallic oxide. Based on achieve electrochemical performance, these 3D-printed devices deliver performance comparable to the energy storage device fabricated using traditional methods still leaving large room for further improvement. Finally, perspectives are provided on the potential future direction of 3D printing for all solid-state electrochemical energy storage devices.

Revelation of graphene-Au for direct write deposition and characterization

Directory of Open Access Journals (Sweden)

Deepa Melepurath

2011-01-01

Full Text Available Abstract Graphene nanosheets were prepared using a modified Hummer's method, and Au-graphene nanocomposites were fabricated by in situ reduction of a gold salt. The as-produced graphene was characterized by X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM. In particular, the HR-TEM demonstrated the layered crystallites of graphene with fringe spacing of about 0.32 nm in individual sheets and the ultrafine facetted structure of about 20 to 50 nm of Au particles in graphene composite. Scanning helium ion microscopy (HIM technique was employed to demonstrate direct write deposition on graphene by lettering with gaps down to 7 nm within the chamber of the microscope. Bare graphene and graphene-gold nanocomposites were further characterized in terms of their composition and optical and electrical properties.

On Embedding N2R Structures in Optical Fiber OMS-SP Ring

DEFF Research Database (Denmark)

Riaz, Muhammad Tahir; Pedersen, Jens Myrup; Nielsen, Rasmus Hjorth

2006-01-01

The objective of this paper is to propose methods for embedding N2R structures in optical fiber OMS-SP rings. The OMS-SP ring supports full mesh structure and restoration on the optical level. The N2R structures have been proven to be superior to other degree 3 network structures. Two main mapping...

Potential for GPC-based laser direct writing

DEFF Research Database (Denmark)

Bañas, Andrew; Glückstad, Jesper

2016-01-01

lasers for such applications by using phase modulation as opposed to amplitude truncating masks. Here, we explore GPC’s potential for increasing the yield of micropscopic 3D printing also known as direct laser writing. Many light based additive manufacturing techniques, adopt a point scanning approach...

Femtosecond single-beam direct laser poling of stable and efficient second-order nonlinear optical properties in glass

International Nuclear Information System (INIS)

Papon, G.; Marquestaut, N.; Royon, A.; Canioni, L.; Petit, Y.; Dussauze, M.; Rodriguez, V.; Cardinal, T.

2014-01-01

We depict a new approach for the localized creation in three dimensions (3D) of a highly demanded nonlinear optical function for integrated optics, namely second harmonic generation. We report on the nonlinear optical characteristics induced by single-beam femtosecond direct laser writing in a tailored silver-containing phosphate glass. The original spatial distribution of the nonlinear pattern, composed of four lines after one single laser writing translation, is observed and modeled with success, demonstrating the electric field induced origin of the second harmonic generation. These efficient second-order nonlinear structures (with χ eff (2)  ∼ 0.6 pm V −1 ) with sub-micron scale are impressively stable under thermal constraint up to glass transition temperature, which makes them very promising for new photonic applications, especially when 3D nonlinear architectures are desired

The temperature and tension characteristics of the FBGs embedded in the polythene sheath of an optical cable

Science.gov (United States)

Chen, Guanghui; Zhao, Ming; Sha, Jianbo; Zhang, Jun; Wu, Bingyan; Lin, Chen; Zhang, Mingliang; Gao, Kan

2015-10-01

The five of FBG were embedded in the PE sheath of a tether optical cable, which has about 18mm diameter and 7000mm length. The temperature and tension characteristics of the FBGs embedded in the polythene (PE) sheath had been demonstrated quantitatively. The Bragg wavelength of the embedded FBG shift linearly with the change of pulling force loaded on the tether optical cable and its tension sensitivity is about 3.75 pm/kg. The results of temperature experiment suggest the embedded FBG have been sensitized by PE material, so that its temperature sensitivity increase from 9.37pm/°C to about 12.51pm/°C.

Large-Scale Direct-Writing of Aligned Nanofibers for Flexible Electronics.

Science.gov (United States)

Ye, Dong; Ding, Yajiang; Duan, Yongqing; Su, Jiangtao; Yin, Zhouping; Huang, Yong An

2018-05-01

Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well-patterned microstructures in flexible electronics. Electro-hydrodynamic (EHD) direct-writing technology enables large-scale deposition of highly aligned nanofibers in an additive, noncontact, real-time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground-breaking research progress in the field of EHD direct-writing technology is summarized, including a brief chronology of EHD direct-writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct-written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An embedded optical tracking system for motion-corrected magnetic resonance imaging at 7T.

Science.gov (United States)

Schulz, Jessica; Siegert, Thomas; Reimer, Enrico; Labadie, Christian; Maclaren, Julian; Herbst, Michael; Zaitsev, Maxim; Turner, Robert

2012-12-01

Prospective motion correction using data from optical tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel optical embedded tracking system. The home-built optical embedded tracking system performs image processing within a 7 T scanner bore, enabling high speed tracking. Corrected and uncorrected in vivo MR volumes are acquired interleaved using a modified 3D FLASH sequence, and their image quality is assessed and compared. The latency between motion and correction of the slice position was measured to be (19 ± 5) ms, and the tracking noise has a standard deviation no greater than 10 μm/0.005° during conventional MR scanning. Prospective motion correction improved the edge strength by 16 % on average, even though the volunteers were asked to remain motionless during the acquisitions. Using a novel method for validating the effectiveness of in vivo prospective motion correction, we have demonstrated that prospective motion correction using motion data from the embedded tracking system considerably improved image quality.

Protection of critical infrastructure using fiber optic sensors embedded in technical textiles

Science.gov (United States)

Krebber, Katerina; Lenke, Philipp; Liehr, Sascha; Noether, Nils; Wendt, Mario; Wosniok, Aleksander

2010-04-01

Terrorists and criminals more and more attack and destroy important infrastructures like routes, railways, bridges, tunnels, dikes and dams, important buildings. Therefore, reliable on-line and long-term monitoring systems are required to protect such critical infrastructures. Fiber optic sensors are well-suited for that. They can be installed over many kilometers and are able to measure continuously distributed strain, pressure, temperature and further mechanical and physical quantities. The very tiny optical fibers can be integrated into structures and materials and can provide information about any significant changes or damages of the structures. These so-called smart materials and smart structures are able to monitor itself or its environment. Particularly smart technical textiles with embedded fiber optic sensors have become very attractive because of their high importance for the structural health monitoring of geotechnical and masonry infrastructures. Such textiles are usually used for reinforcement of the structures; the embedded fiber optic sensors provide information about the condition of the structures and detect the presence of any damages and destructions in real time. Thus, critical infrastructures can be preventively protected. The paper will introduce this innovative field and will present the results achieved within several German and European projects.

Laser direct writing (LDW of magnetic structures

Directory of Open Access Journals (Sweden)

Alaa Alasadi

2018-05-01

Full Text Available Laser direct writing (LDW has been used to pattern 90nm thick permalloy (Ni81Fe19 into 1-D and 2-D microstructures with strong shape anisotropy. Sub-nanosecond laser pulses were focused with a 0.75 NA lens to a 1.85μm diameter spot, to achieve a fluence of approximately 350 mJ.cm-2 and ablate the permalloy film. Computer-controlled sample scanning then allowed structures to be defined. Scan speeds were controlled to give 30% overlap between successive laser pulses and reduce the extent of width modulation in the final structures. Continuous magnetic wires that adjoined the rest of the film were fabricated with widths from 650 nm - 6.75μm and magneto-optical measurements showed coercivity reducing across this width range from 47 Oe to 11 Oe. Attempts to fabricate wires narrower than 650nm resulted in discontinuities in the wires and a marked decrease in coercivity. This approach is extremely rapid and was carried out in air, at room temperature and with no chemical processing. The 6-kHz laser pulse repetition rate allowed wire arrays across an area of 4 mm x 0.18 mm to be patterned in 85 s.

Laser direct writing (LDW) of magnetic structures

Science.gov (United States)

Alasadi, Alaa; Claeyssens, F.; Allwood, D. A.

2018-05-01

Laser direct writing (LDW) has been used to pattern 90nm thick permalloy (Ni81Fe19) into 1-D and 2-D microstructures with strong shape anisotropy. Sub-nanosecond laser pulses were focused with a 0.75 NA lens to a 1.85μm diameter spot, to achieve a fluence of approximately 350 mJ.cm-2 and ablate the permalloy film. Computer-controlled sample scanning then allowed structures to be defined. Scan speeds were controlled to give 30% overlap between successive laser pulses and reduce the extent of width modulation in the final structures. Continuous magnetic wires that adjoined the rest of the film were fabricated with widths from 650 nm - 6.75μm and magneto-optical measurements showed coercivity reducing across this width range from 47 Oe to 11 Oe. Attempts to fabricate wires narrower than 650nm resulted in discontinuities in the wires and a marked decrease in coercivity. This approach is extremely rapid and was carried out in air, at room temperature and with no chemical processing. The 6-kHz laser pulse repetition rate allowed wire arrays across an area of 4 mm x 0.18 mm to be patterned in 85 s.

Rapid selective metal patterning on polydimethylsiloxane (PDMS) fabricated by capillarity-assisted laser direct write

KAUST Repository

Lee, Ming-Tsang; Lee, Daeho; Sherry, Alexander; Grigoropoulos, Costas P

2011-01-01

direct write (LDW) technology. To achieve good metal film quality, a capillarity-assisted laser direct writing (CALDW) of nanoparticle suspensions on a low surface energy material (PDMS) was utilized. Experimental results showed controllable electrical

Vibration measurement on composite material with embedded optical fiber based on phase-OTDR

Science.gov (United States)

Franciscangelis, C.; Margulis, W.; Floridia, C.; Rosolem, J. B.; Salgado, F. C.; Nyman, T.; Petersson, M.; Hallander, P.; Hällstrom, S.; Söderquist, I.; Fruett, F.

2017-04-01

Distributed sensors based on phase-optical time-domain reflectometry (phase-OTDR) are suitable for aircraft health monitoring due to electromagnetic interference immunity, small dimensions, low weight and flexibility. These features allow the fiber embedment into aircraft structures in a nearly non-intrusive way to measure vibrations along its length. The capability of measuring vibrations on avionics structures is of interest for what concerns the study of material fatigue or the occurrence of undesirable phenomena like flutter. In this work, we employed the phase-OTDR technique to measure vibrations ranging from some dozens of Hz to kHz in two layers of composite material board with embedded polyimide coating 0.24 numerical aperture single-mode optical fiber.

Engineering of refractive index in sulfide chalcogenide glass by direct laser writing

KAUST Repository

Zhang, Yaping

2010-01-01

Arsenic trisulfide (As2S3) glass is an interesting material for photonic integrated circuits (PICs) as infrared (IR) or nonlinear optical components. In this paper, direct laser writing was applied to engineer the refractive index of As2S3 thin film. Film samples were exposed to focused above bandgap light with wavelength at 405 nm using different fluence adjusted by laser power and exposure time. The index of refraction before and after laser irradiation was calculated by fitting the experimental data obtained from Spectroscopic Ellipsometer (SE) measurement to Tauc-Lorenz dispersion formula. A positive change in refractive index (Δn = 0.19 at 1.55 μm) as well as an enhancement in anisotropy was achieved in As2S3 film by using 10 mW, 0.3 μs laser irradiation. With further increasing the fluence, refractive index increased while anisotropic property weakened. Due to the rapid and large photo-induced modification of refractive index obtainable with high spatial resolution, this process is promising for integrated optic device fabrication.

Dynamic exposure model analysis of continuous laser direct writing in Polar-coordinate

Science.gov (United States)

Zhang, Shan; Lv, Yingjun; Mao, Wenjie

2018-01-01

In order to exactly predict the continuous laser direct writing quality in Polar-coordinate, we take into consideration the effect of the photoresist absorbing beam energy, the Gaussian attribute of the writing beam and the dynamic exposure process, and establish a dynamic exposure model to describe the influence of the tangential velocity of the normal incident facular center and laser power on the line width and sidewall angle. Numerical simulation results indicate that while writing velocity remains unchanged, the line width and sidewall angle are all increased as the laser power increases; while laser power remains unchanged, the line width and sidewall angle are all decreased as the writing velocity increases; at the same time the line profile in the exposure section is asymmetry and the center of the line has tiny excursion toward the Polar-coordinate origin compared with the facular center. Then it is necessary to choose the right writing velocity and laser power to obtain the ideal line profile. The model makes up the shortcomings of traditional models that can only predict line width or estimate the profile of the writing line in the absence of photoresist absorption, and can be considered as an effect analysis method for optimizing the parameters of fabrication technique of laser direct writing.

The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer

KAUST Repository

Lee, Jung-Yong

2010-04-29

We analyze the enhancement in optical absorption of an absorbing medium when spherical metal nanoparticles are embedded in it. Our analysis uses generalized Mie theory to calculate the absorbed optical power as a function of the distance from the metal nanoparticle. This analysis is used to evaluate the potential of enhancing optical absorption in thin-film solar cells by embedding spherical metal nanoparticles. We consider the trade-off between maximizing overall optical absorption and ensuring that a large fraction of the incident optical power is dissipated in the absorbing host medium rather than in the metal nanoparticle. We show that enhanced optical absorption results from strong scattering by the metal nanoparticle which locally enhances the optical electric fields. We also discuss the effect of a thin dielectric encapsulation of the metal nanoparticles. ©2010 Optical Society of America.

The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer

KAUST Repository

Lee, Jung-Yong; Peumans, Peter

2010-01-01

We analyze the enhancement in optical absorption of an absorbing medium when spherical metal nanoparticles are embedded in it. Our analysis uses generalized Mie theory to calculate the absorbed optical power as a function of the distance from the metal nanoparticle. This analysis is used to evaluate the potential of enhancing optical absorption in thin-film solar cells by embedding spherical metal nanoparticles. We consider the trade-off between maximizing overall optical absorption and ensuring that a large fraction of the incident optical power is dissipated in the absorbing host medium rather than in the metal nanoparticle. We show that enhanced optical absorption results from strong scattering by the metal nanoparticle which locally enhances the optical electric fields. We also discuss the effect of a thin dielectric encapsulation of the metal nanoparticles. ©2010 Optical Society of America.

Energy-aware virtual network embedding in flexi-grid optical networks

Science.gov (United States)

Lin, Rongping; Luo, Shan; Wang, Haoran; Wang, Sheng; Chen, Bin

2018-01-01

Virtual network embedding (VNE) problem is to map multiple heterogeneous virtual networks (VN) on a shared substrate network, which mitigate the ossification of the substrate network. Meanwhile, energy efficiency has been widely considered in the network design. In this paper, we aim to solve the energy-aware VNE problem in flexi-grid optical networks. We provide an integer linear programming (ILP) formulation to minimize the power increment of each arriving VN request. We also propose a polynomial-time heuristic algorithm where virtual links are embedded sequentially to keep a reasonable acceptance ratio and maintain a low energy consumption. Numerical results show the functionality of the heuristic algorithm in a 24-node network.

High-throughput fabrication of micrometer-sized compound parabolic mirror arrays by using parallel laser direct-write processing

International Nuclear Information System (INIS)

Yan, Wensheng; Gu, Min; Cumming, Benjamin P

2015-01-01

Micrometer-sized parabolic mirror arrays have significant applications in both light emitting diodes and solar cells. However, low fabrication throughput has been identified as major obstacle for the mirror arrays towards large-scale applications due to the serial nature of the conventional method. Here, the mirror arrays are fabricated by using a parallel laser direct-write processing, which addresses this barrier. In addition, it is demonstrated that the parallel writing is able to fabricate complex arrays besides simple arrays and thus offers wider applications. Optical measurements show that each single mirror confines the full-width at half-maximum value to as small as 17.8 μm at the height of 150 μm whilst providing a transmittance of up to 68.3% at a wavelength of 633 nm in good agreement with the calculation values. (paper)

Optical characterizations of silver nanoprisms embedded in polymer thin film layers

Science.gov (United States)

Carlberg, Miriam; Pourcin, Florent; Margeat, Olivier; Le Rouzo, Judikael; Berginc, Gerard; Sauvage, Rose-Marie; Ackermann, Jorg; Escoubas, Ludovic

2017-10-01

The precise control of light-matter interaction has a wide range of applications and is currently driven by the use of nanoparticles (NPs) by the recent advances in nanotechnology. Taking advantage of the material, size, shape, and surrounding media dependence of the optical properties of plasmonic NPs, thin film layers with tunable optical properties are achieved. The NPs are synthesized by wet chemistry and embedded in a polyvinylpyrrolidone (PVP) polymer thin film layer. Spectrophotometer and spectroscopic ellipsometry measurements are coupled to finite-difference time domain numerical modeling to optically characterize the heterogeneous thin film layers. Silver nanoprisms of 10 to 50 nm edge size exhibit high absorption through the visible wavelength range. A simple optical model composed of a Cauchy law and a Lorentz law, accounting for the optical properties of the nonabsorbing polymer and the absorbing property of the nanoprisms, fits the spectroscopic ellipsometry measurements. Knowing the complex optical indices of heterogeneous thin film layers let us design layers of any optical properties.

Physical model for the incoherent writing/erasure of cavity solitons in semiconductor optical amplifiers.

Science.gov (United States)

Barbay, S; Kuszelewicz, R

2007-09-17

We present a physical mechanism that explains the recent observations of incoherent writing and erasure of Cavity Solitons in a semiconductor optical amplifier [S. Barbay et al, Opt. Lett. 31, 1504-1506 (2006)]. This mechanism allows to understand the main observations of the experiment. In particular it perfectly explains why writing and erasure are possible as a result of a local perturbation in the carrier density, and why a delay is observed along with the writing process. Numerical simulations in 1D are performed and show very good qualitative agreement with the experimental observations.

Silicon photonic IC embedded optical-PCB for high-speed interconnect application

Science.gov (United States)

Kallega, Rakshitha; Nambiar, Siddharth; Kumar, Abhai; Ranganath, Praveen; Selvaraja, Shankar Kumar

2018-02-01

Optical-Printed Circuit Board (PCB) is an emerging optical interconnect technology to bridge the gap between the board edge and the processing module. The technology so far has been used as a broadband transmitter using polymer waveguides in the PCB. In this paper, we report a Silicon Nitride based photonic IC embedded in the PCB along with the polymers as waveguides in the PCB. The motivation for such integration is to bring routing capability and to reduce the power loss due to broadcasting mode.

Direct writing of conductive silver micropatterns on flexible polyimide film by laser-induced pyrolysis of silver nanoparticle-dispersed film

International Nuclear Information System (INIS)

Aminuzzaman, Mohammod; Watanabe, Akira; Miyashita, Tokuji

2010-01-01

This article describes fabrication of Ag micropatterns on a flexible polyimide (PI) film by laser direct writing using an Ag nanoparticle-dispersed film as a precursor. Ag micropatterns are characterized by optical microscopy, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), surface profilometry, and resistivity measurements. The line width of Ag micropatterns can be effectively controlled by altering the experimental parameters of laser direct writing especially laser intensity, objective lens, and laser beam scanning speed etc. Using an objective lens of 100x and laser intensity of 170.50 kW/cm 2 , Ag micropatterns with a line width of about 6 μm have been achieved. The Ag micropatterns show strong adhesion to polyimide surface as evaluated by Scotch-tape test. The resistivity of the Ag micropatterns is determined to be 4.1 x 10 -6 Ω cm using two-point probe method. This value is comparable with the resistivity of bulk Ag (1.6 x 10 -6 Ω cm).

Molecule-by-Molecule Writing Using a Focused Electron Beam

DEFF Research Database (Denmark)

Van Dorp, Willem F.; Zhang, Xiaoyan; Feringa, Ben L.

2012-01-01

atoms also be written with an electron beam? We verify this with focused electron-beam-induced deposition (FEBID), a direct-write technique that has the current record for the smallest feature written by (electron) optical lithography. We show that the deposition of an organometallic precursor...... on graphene can be followed molecule-by-molecule with FEBID. The results show that mechanisms that are inherent to the process inhibit a further increase in control over the process. Hence, our results present the resolution limit of (electron) optical lithography techniques. The writing of isolated...

Ambient light-based optical biosensing platform with smartphone-embedded illumination sensor.

Science.gov (United States)

Park, Yoo Min; Han, Yong Duk; Chun, Hyeong Jin; Yoon, Hyun C

2017-07-15

We present a hand-held optical biosensing system utilizing a smartphone-embedded illumination sensor that is integrated with immunoblotting assay method. The smartphone-embedded illumination sensor is regarded as an alternative optical receiver that can replaces the conventional optical analysis apparatus because the illumination sensor can respond to the ambient light in a wide range of wavelengths, including visible and infrared. To demonstrate the biosensing applicability of our system employing the enzyme-mediated immunoblotting and accompanying light interference, various types of ambient light conditions including outdoor sunlight and indoor fluorescent were tested. For the immunoblotting assay, the biosensing channel generating insoluble precipitates as an end product of the enzymatic reaction is fabricated and mounted on the illumination sensor of the smartphone. The intensity of penetrating light arrives on the illumination sensor is inversely proportional to the amount of precipitates produced in the channel, and these changes are immediately analyzed and quantified via smartphone software. In this study, urinary C-terminal telopeptide fragment of type II collagen (uCTX-II), a biomarker of osteoarthritis diagnosis, was tested as a model analyte. The developed smartphone-based sensing system efficiently measured uCTX-II in the 0-5ng/mL concentration range with a high sensitivity and accuracy under various light conditions. These assay results show that the illumination sensor-based optical biosensor is suitable for point-of-care testing (POCT). Copyright © 2016 Elsevier B.V. All rights reserved.

UV written 1x8 optical splitters

DEFF Research Database (Denmark)

Olivero, Massimo; Svalgaard, Mikael

2005-01-01

In this paper the first demonstration of 1x8 optical power splitters made by direct UV writing is presented. Design and optimization of the process as well as the performance of the fabricated components are discussed.......In this paper the first demonstration of 1x8 optical power splitters made by direct UV writing is presented. Design and optimization of the process as well as the performance of the fabricated components are discussed....

Femtosecond laser inscription of asymmetric directional couplers for in-fiber optical taps and fiber cladding photonics.

Science.gov (United States)

Grenier, Jason R; Fernandes, Luís A; Herman, Peter R

2015-06-29

Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits.

3-D printed sensing patches with embedded polymer optical fibre Bragg gratings

DEFF Research Database (Denmark)

Zubel, Michal G.; Sugden, Kate; Saez-Rodriguez, D.

2016-01-01

The first demonstration of a polymer optical fibre Bragg grating (POFBG) embedded in a 3-D printed structure is reported. Its cyclic strain performance and temperature characteristics are examined and discussed. The sensing patch has a repeatable strain sensitivity of 0.38 pm/mu epsilon. Its...

Direct writing of flexible electronics through room temperature liquid metal ink.

Science.gov (United States)

Gao, Yunxia; Li, Haiyan; Liu, Jing

2012-01-01

Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn(10)-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. The electrical resistivity of the fluid like GaIn(10)-based material was measured as 34.5 µΩ·cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 µm thick. Several functional devices such as a light emitting diode (LED) array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn(10)-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized purpose and can be extended to more industrial areas, even

Direct writing of flexible electronics through room temperature liquid metal ink.

Directory of Open Access Journals (Sweden)

Yunxia Gao

Full Text Available BACKGROUND: Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn(10-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. METHODS: The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. RESULTS: The electrical resistivity of the fluid like GaIn(10-based material was measured as 34.5 µΩ·cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 µm thick. Several functional devices such as a light emitting diode (LED array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. CONCLUSIONS: The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn(10-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized

A Micro-Computed Tomography Technique to Study the Quality of Fibre Optics Embedded in Composite Materials

Directory of Open Access Journals (Sweden)

Gabriele Chiesura

2015-05-01

Full Text Available Quality of embedment of optical fibre sensors in carbon fibre-reinforced polymers plays an important role in the resultant properties of the composite, as well as for the correct monitoring of the structure. Therefore, availability of a tool able to check the optical fibre sensor-composite interaction becomes essential. High-resolution 3D X-ray Micro-Computed Tomography, or Micro-CT, is a relatively new non-destructive inspection technique which enables investigations of the internal structure of a sample without actually compromising its integrity. In this work the feasibility of inspecting the position, the orientation and, more generally, the quality of the embedment of an optical fibre sensor in a carbon fibre reinforced laminate at unit cell level have been proven.

Optical Fiber Sensors Based on Nanoparticle-Embedded Coatings

Directory of Open Access Journals (Sweden)

Aitor Urrutia

2015-01-01

Full Text Available The use of nanoparticles (NPs in scientific applications has attracted the attention of many researchers in the last few years. The use of NPs can help researchers to tune the physical characteristics of the sensing coating (thickness, roughness, specific area, refractive index, etc. leading to enhanced sensors with response time or sensitivity better than traditional sensing coatings. Additionally, NPs also offer other special properties that depend on their nanometric size, and this is also a source of new sensing applications. This review focuses on the current status of research in the use of NPs within coatings in optical fiber sensing. Most used sensing principles in fiber optics are briefly described and classified into several groups: absorbance-based sensors, interferometric sensors, fluorescence-based sensors, fiber grating sensors, and resonance-based sensors, among others. For each sensor group, specific examples of the utilization of NP-embedded coatings in their sensing structure are reported.

Femtosecond laser writing of a flat-top interleaver via cascaded Mach-Zehnder interferometers.

Science.gov (United States)

Ng, Jason C; Li, Chengbo; Herman, Peter R; Qian, Li

2012-07-30

A flat-top interleaver consisting of cascaded Mach-Zehnder interferometers (MZIs) was fabricated in bulk glass by femtosecond laser direct writing. Spectral contrast ratios of greater than 15 dB were demonstrated over a 30 nm bandwidth for 3 nm channel spacing. The observed spectral response agreed well with a standard transfer matrix model generated from responses of individual optical components, demonstrating the possibility for multi-component optical design as well as sufficient process accuracy and fabrication consistency for femtosecond laser writing of advanced optical circuits in three dimensions.

Programming Embedded Systems With C and GNU Development Tools

CERN Document Server

Barr, Michael

2009-01-01

Whether you're writing your first embedded program, designing the latest generation of hand-held whatchamacalits, or managing the people who do, this book is for you. Programming Embedded Systems will help you develop the knowledge and skills you need to achieve proficiency with embedded software.

Highly transparent and conductive Al-doped ZnO nanoparticulate thin films using direct write processing

International Nuclear Information System (INIS)

Vunnam, S; Ankireddy, K; Kellar, J; Cross, W

2014-01-01

Solution processable Al-doped ZnO (AZO) thin films are attractive candidates for low cost transparent electrodes. We demonstrate here an optimized nanoparticulate ink for the fabrication of AZO thin films using scalable, low-cost direct write processing (ultrasonic spray deposition) in air at atmospheric pressure. The thin films were made via thermal processing of as-deposited films. AZO films deposited using the proposed nanoparticulate ink with further reducing in vacuum and rf plasma of forming gas exhibited optical transparency greater than 95% across the visible spectrum, and electrical resistivity of 0.5 Ω cm and it drops down to 7.0 × 10 −2 Ω cm after illuminating with UV light, which is comparable to commercially available tin doped indium oxide colloidal coatings. Various structural analyses were performed to investigate the influence of ink chemistry, deposition parameters, and annealing temperatures on the structural, optical, and electrical characteristics of the spray deposited AZO thin films. Optical micrographs confirmed the presence of surface defects and cracks using the AZO NPs ink without any additives. After adding N-(2-Aminoethyl)-3-aminopropylmethyldimethoxy silane to the ink, AZO films exhibited an optical transparency which was virtually identical to that of the plain glass substrate. (papers)

Direct write printing of three-dimensional ZrO2 biological scaffolds

International Nuclear Information System (INIS)

Li, Ya-yun; Li, Long-tu; Li, Bo

2015-01-01

Graphical abstract: Three-dimensional (3D) zirconium dioxide (ZrO 2 ) scaffolds have been fabricated for biological engineering by direct write printing method. The water-based ZrO 2 ink with a solid content fraction of 70 wt% was deposited through a fine nozzle on the substrate by a layer-by-layer sequence to produce the 3D microperiodic structures. Under a microscope, the proliferation of HCT116 cells can be observed around the 3D ZrO 2 scaffolds. 3D porous internal architecture is beneficial for cell growth by providing more locations for cell attachment and proliferation. The largest value of compressive strength reached 10 MPa, which is more than that of the hydroxyapatite (HAp) scaffold. The ability of printing 3D scaffolds with the high precise control of their internal architecture is the unique characteristics performed by the direct write technique, which will provide potential application of biomaterials and tissue engineering scaffolds. (a) Top view of the sintered 3D woodpile ZrO 2 scaffold; (b) top view of the sintered 3D cylindrical ZrO 2 scaffold. - Highlights: • 3D cylindrical and woodpile ZrO 2 scaffolds were fabricated by direct write printing method. • The compressive strength of the sample with porosity about 63% was 8 MPa. • The compressive strength of the porosity 55% sample was 10 MPa. • 3D porous ZrO 2 scaffolds with interconnected architecture are beneficial for cell attachment and proliferation. - Abstract: Three-dimensional (3D) zirconium dioxide (ZrO 2 ) scaffolds have been fabricated for biological engineering by direct write printing method. The water-based ZrO 2 ink with a solid content fraction of 70 wt% was deposited through a fine nozzle on the substrate by a layer-by-layer sequence to produce the 3D microperiodic structures. The preparation and the rheological behavior of this ink, as well as the principles of the direct write printing process were investigated systematically. Sintered at 1250 °C for 4 h was the optimal

Effects of direct instruction and strategy modeling on upper-primary students' writing development

NARCIS (Netherlands)

López, P.; Torrance, M.; Rijlaarsdam, G.; Fidalgo, R.

Strategy-focused instruction is one of the most effective approaches to improve writing skills. It aims to teach developing writers strategies that give them executive control over their writing processes. Programs under this kind of instruction tend to have multiple components that include direct

Experimental study of optical fibers influence on composite

Science.gov (United States)

Liu, Rong-Mei; Liang, Da-Kai

2010-03-01

Bending strength and elasticity modulus of composite, with and without embedded optical fibers, were experimentally studied. Two kinds of laminates, which were denoted as group 1 and group 2, were fabricated from an orthogonal woven glass/epoxy prepreg. Since the normal stress value becomes the biggest at the surface of a beam, the optical fibers were embedded at the outmost layer and were all along the loading direction. Four types of materials, using each kind of laminated prepreg respectively, were manufactured. The embedded optical fibers for the 4 material types were 0, 10, 30 and 50 respectively. Three-point bending tests were carried out on the produced specimens to study the influence of embedded optical fiber on host composite. The experimental results indicated that the materials in group 2 were more sensitive to the embedded optical fibers.

Pervasive liquid metal based direct writing electronics with roller-ball pen

Directory of Open Access Journals (Sweden)

Yi Zheng

2013-11-01

Full Text Available A roller-ball pen enabled direct writing electronics via room temperature liquid metal ink was proposed. With the rolling to print mechanism, the metallic inks were smoothly written on flexible polymer substrate to form conductive tracks and electronic devices. The contact angle analyzer and scanning electron microscope were implemented to disclose several unique inner properties of the obtained electronics. An ever high writing resolution with line width and thickness as 200 μm and 80 μm, respectively was realized. Further, with the administration of external writing pressure, GaIn24.5 droplets embody increasing wettability on polymer which demonstrates the pervasive adaptability of the roller-ball pen electronics.

Embedded Distributed Optical Fiber Sensors in Reinforced Concrete Structures-A Case Study.

Science.gov (United States)

Barrias, António; Casas, Joan R; Villalba, Sergi

2018-03-26

When using distributed optical fiber sensors (DOFS) on reinforced concrete structures, a compromise must be achieved between the protection requirements and robustness of the sensor deployment and the accuracy of the measurements both in the uncracked and cracked stages and under loading, unloading and reloading processes. With this in mind the authors have carried out an experiment where polyimide-coated DOFS were installed on two concrete beams, both embedded in the rebar elements and also bonded to the concrete surface. The specimens were subjected to a three-point load test where after cracking, they are unloaded and reloaded again to assess the capability of the sensor when applied to a real loading scenarios in concrete structures. Rayleigh Optical Frequency Domain Reflectometry (OFDR) was used as the most suitable technique for crack detection in reinforced concrete elements. To verify the reliability and accuracy of the DOFS measurements, additional strain gauges were also installed at three locations along the rebar. The results show the feasibility of using a thin coated polyimide DOFS directly bonded on the reinforcing bar without the need of indention or mechanization. A proposal for a Spectral Shift Quality (SSQ) threshold is also obtained and proposed for future works when using polyimide-coated DOFS bonded to rebars with cyanoacrylate adhesive.

Embedded Distributed Optical Fiber Sensors in Reinforced Concrete Structures—A Case Study

Science.gov (United States)

Villalba, Sergi

2018-01-01

When using distributed optical fiber sensors (DOFS) on reinforced concrete structures, a compromise must be achieved between the protection requirements and robustness of the sensor deployment and the accuracy of the measurements both in the uncracked and cracked stages and under loading, unloading and reloading processes. With this in mind the authors have carried out an experiment where polyimide-coated DOFS were installed on two concrete beams, both embedded in the rebar elements and also bonded to the concrete surface. The specimens were subjected to a three-point load test where after cracking, they are unloaded and reloaded again to assess the capability of the sensor when applied to a real loading scenarios in concrete structures. Rayleigh Optical Frequency Domain Reflectometry (OFDR) was used as the most suitable technique for crack detection in reinforced concrete elements. To verify the reliability and accuracy of the DOFS measurements, additional strain gauges were also installed at three locations along the rebar. The results show the feasibility of using a thin coated polyimide DOFS directly bonded on the reinforcing bar without the need of indention or mechanization. A proposal for a Spectral Shift Quality (SSQ) threshold is also obtained and proposed for future works when using polyimide-coated DOFS bonded to rebars with cyanoacrylate adhesive. PMID:29587449

Diffractive optical elements written by photodeposition

International Nuclear Information System (INIS)

Baal-Zedaka, I.; Hava, S.; Mirchin, N.; Margolin, R.; Zagon, M.; Lapsker, I.; Azoulay, J.; Peled, A.

2003-01-01

In this work direct laser writing of diffractive optical elements (DOE) by photodeposition (PD) of amorphous selenium (a-Se) from colloid solutions has been investigated. We used a computer controlled laser scanner for patterning thin film micro-profiles creating thus planar optical elements by direct beam writing on surfaces immersed in a liquid phase PD cell. The laser employed was an argon ion laser at 488 nm wavelength, with powers up to 55 mW, for writing typically 25-250 μm wide lines of 200 nm thickness at rates of about 150 μm/s. Various elements made of photodeposited thin films on polymethyl-methacrylate (PMMA) substrates were produced for prototyping microlenses, linear grating arrays, cylindrical and circular profiled DOE patterns

On Gendered Technologies and Cyborg Writing

DEFF Research Database (Denmark)

Muhr, Sara Louise; Rehn, Alf

2015-01-01

Since Hélène Cixous introduced it in 1975, the notion of a specifically feminine writing — écriture féminine — has been discussed as a provocative and potentially disruptive form of representation that breaks with masculine and authoritarian modes thereof. However, in this paper we will discuss how......, as the writer — when writing/publishing — is always already embedded in the technologies of the publishing machine, turning (academic) writing into something akin to cyborg writing. We further suggest that an understanding of the cyborg nature of writing can introduce a parallel mode of inquiry, which holds...

Laser deposition and direct-writing of thermoelectric misfit cobaltite thin films

Science.gov (United States)

Chen, Jikun; Palla-Papavlu, Alexandra; Li, Yulong; Chen, Lidong; Shi, Xun; Döbeli, Max; Stender, Dieter; Populoh, Sascha; Xie, Wenjie; Weidenkaff, Anke; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas

2014-06-01

A two-step process combining pulsed laser deposition of calcium cobaltite thin films and a subsequent laser induced forward transfer as micro-pixel is demonstrated as a direct writing approach of micro-scale thin film structures for potential applications in thermoelectric micro-devices. To achieve the desired thermo-electric properties of the cobaltite thin film, the laser induced plasma properties have been characterized utilizing plasma mass spectrometry establishing a direct correlation to the corresponding film composition and structure. The introduction of a platinum sacrificial layer when growing the oxide thin film enables a damage-free laser transfer of calcium cobaltite thereby preserving the film composition and crystallinity as well as the shape integrity of the as-transferred pixels. The demonstrated direct writing approach simplifies the fabrication of micro-devices and provides a large degree of flexibility in designing and fabricating fully functional thermoelectric micro-devices.

Using PELA to Predict International Business Students' English Writing Performance with Contextualised English Writing Workshops as Intervention Program

Science.gov (United States)

Wong, Caroline; Delante, Nimrod Lawsin; Wang, Pengji

2017-01-01

This study examines the effectiveness of Post-Entry English Language Assessment (PELA) as a predictor of international business students' English writing performance and academic performance. An intervention involving the implementation of contextualised English writing workshops was embedded in a specific business subject targeted at students who…

A new direction-sensitive optical module for deep-sea neutrino telescopy

International Nuclear Information System (INIS)

Brunoldi, Marco

2009-01-01

Within the KM3NeT framework, the NEMO (NEutrino Mediterranean Observatory) project is studying new technologies for a km 3 -scale neutrino telescope in the Mediterranean Sea. The telescope goal will be the investigation of the high-energy component of the cosmic neutrino spectrum: a promising tool to better understand the mechanisms that originate extreme-energy cosmic rays. Neutrino energy and direction will be reconstructed using the Cherenkov light produced in water by muons coming from neutrino interactions. Two prototypes of a new large-area (10 in.) 4-anode photomultipliers, manufactured by Hamamatsu at the request of the NEMO Collaboration, have been extensively studied. These tubes will be integrated into spherical glass pressure-resistant optical modules and used for the first time to detect the direction of the detected Cherenkov light at the NEMO deep-sea (3600 m) site near Capo Passero in Sicily. The photocathode surface in these optical modules will be effectively divided into four quadrants by a pair of crescent-shaped mirrors embedded in the optical gel linking the PMT to the glass pressure sphere. A series of measurements was performed at the testing facility of the NEMO group at the INFN Sezione di Catania. The single photoelectron peak, the transit time spread, the gain and the cross-talk of the prototype have been studied, to have a complete characterization and make feasible a comparison with previous models. The first prototype of direction-sensitive optical module has been assembled and tested with a dedicated experimental setup at the INFN Sezione di Genova. First results of tests of the prototype are presented.

Direct writing of sub-wavelength ripples on silicon using femtosecond laser at high repetition rate

International Nuclear Information System (INIS)

Xie, Changxin; Li, Xiaohong; Liu, Kaijun; Zhu, Min; Qiu, Rong; Zhou, Qiang

2016-01-01

Graphical abstract: - Highlights: • The NSRs and DSRs are obtained on silicon surface. • With increasing direct writing speed, the NSRs suddenly changes and becomes the DSRs. • We develop a Sipe–Drude interference theory by considering the thermal excitation. - Abstract: The near sub-wavelength and deep sub-wavelength ripples on monocrystalline silicon were formed in air by using linearly polarized and high repetition rate femtosecond laser pulses (f = 76 MHz, λ = 800 nm, τ = 50 fs). The effects of laser pulse energy, direct writing speed and laser polarization on silicon surface morphology are studied. When the laser pulse energy is 2 nJ/pulse and the direct writing speed varies from 10 to 25 mm/s, the near sub-wavelength ripples (NSRs) with orientation perpendicular to the laser polarization are generated. While the direct writing speed reaches 30 mm/s, the direction of the obtained deep sub-wavelength ripples (DSRs) suddenly changes and becomes parallel to the laser polarization, rarely reported so far for femtosecond laser irradiation of silicon. Meanwhile, we extend the Sipe–Drude interference theory by considering the thermal excitation, and numerically calculate the efficacy factor for silicon irradiated by femtosecond laser pulses. The revised Sipe–Drude interference theoretical results show good agreement with the periods and orientations of sub-wavelength ripples.

Highly directive Fabry-Perot leaky-wave nanoantennas based on optical partially reflective surfaces

Energy Technology Data Exchange (ETDEWEB)

Lorente-Crespo, M.; Mateo-Segura, C., E-mail: C.Mateo-Segura@hw.ac.uk [Institute of Sensors, Signals and Systems, Heriot-Watt University, EH14 4AS Edinburgh (United Kingdom)

2015-05-04

Nanoantennas enhance the conversion between highly localized electromagnetic fields and far-field radiation. Here, we investigate the response of a nano-patch partially reflective surface backed with a silver mirror to an optical source embedded at the centre of the structure. Using full wave simulations, we demonstrate a two orders of magnitude increased directivity compared to the isotropic radiator, 50% power confinement to a 13.8° width beam and a ±16 nm bandwidth. Our antenna does not rely on plasmonic phenomena thus reducing non-radiative losses and conserving source coherence.

One-step fabrication of submicrostructures by low one-photon absorption direct laser writing technique with local thermal effect

Science.gov (United States)

Nguyen, Dam Thuy Trang; Tong, Quang Cong; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

2016-01-01

In this work, local thermal effect induced by a continuous-wave laser has been investigated and exploited to optimize the low one-photon absorption (LOPA) direct laser writing (DLW) technique for fabrication of polymer-based microstructures. It was demonstrated that the temperature of excited SU8 photoresist at the focusing area increases to above 100 °C due to high excitation intensity and becomes stable at that temperature thanks to the use of a continuous-wave laser at 532 nm-wavelength. This optically induced thermal effect immediately completes the crosslinking process at the photopolymerized region, allowing obtain desired structures without using the conventional post-exposure bake (PEB) step, which is usually realized after the exposure. Theoretical calculation of the temperature distribution induced by local optical excitation using finite element method confirmed the experimental results. LOPA-based DLW technique combined with optically induced thermal effect (local PEB) shows great advantages over the traditional PEB, such as simple, short fabrication time, high resolution. In particular, it allowed the overcoming of the accumulation effect inherently existed in optical lithography by one-photon absorption process, resulting in small and uniform structures with very short lattice constant.

Advanced applications in microphotonics using proton beam writing

International Nuclear Information System (INIS)

Bettiol, A.A.; Chiam, S.Y.; Teo, E.J.; Udalagama, C.; Chan, S.F.; Hoi, S.K.; Kan, J.A. van; Breese, M.B.H.; Watt, F.

2009-01-01

Proton beam writing (PBW) is a powerful tool for prototyping microphotonic structures in a wide variety of materials including polymers, insulators, semiconductors and metals. Prototyping is achieved either through direct fabrication with the proton beam, or by the fabrication of a master that can be used for replication. In recent times we have explored the use of PBW for various advanced optical applications including fabrication of subwavelength metallic structures and metamaterials, direct write of silicon waveguides for mid IR applications and integrated waveguides for lab-on-a-chip devices. This paper will review the recent progress made in these areas with particular emphasis on the main advantages of using the PBW technique for these novel applications.

Fabrication of 2 × 8 power splitters in silica-on-silicon by the direct UV writing technique

DEFF Research Database (Denmark)

Olivero, Massimo; Svalgaard, Mikael

2006-01-01

In this letter, we present the first demonstration of 2 × 8 power splitters made in silica-on-silicon by direct ultraviolet (UV) writing. The fabricated components are compact and exhibit good performance in terms of loss, uniformity, and bandwidth, showing that direct UV writing can become...

Expressive/Exploratory Technical Writing (XTW) in Engineering: Shifting the Technical Writing Curriculum

Science.gov (United States)

Warnock, Scott; Kahn, Michael

2007-01-01

While the importance of "expressive writing," or informal, self-directed writing, has been well established, teachers underutilize it, particularly in technical writing courses. We introduce the term expressive/exploratory technical writing (XTW), which is the use of informal, self-directed writing to problem-solve in technical fields. We describe…

Rapid selective metal patterning on polydimethylsiloxane (PDMS) fabricated by capillarity-assisted laser direct write

KAUST Repository

Lee, Ming-Tsang

2011-08-12

In this study we demonstrate a novel approach for the rapid fabricating micro scale metal (silver) patterning directly on a polydimethylsiloxane (PDMS) substrate. Silver nanoparticles were sintered on PDMS to form conductive metal films using laser direct write (LDW) technology. To achieve good metal film quality, a capillarity-assisted laser direct writing (CALDW) of nanoparticle suspensions on a low surface energy material (PDMS) was utilized. Experimental results showed controllable electrical conductivities and good film properties of the sintered silver patterns. This study reveals an advanced method of metal patterning on PDMS, and proposes a new research application of LDW in a nanoparticle colloidal environment. © 2011 IOP Publishing Ltd.

Development of an Erlang System Adaopted to Embedded Devices

OpenAIRE

Andersson, Fredrik; Bergström, Fabian

2011-01-01

Erlang is a powerful and robust language for writing massively parallel and distributed applications. With the introduction of multi-core ARM processors, the embedded market will be looking for ways of taking advantage of the newfound opportunities for parallelism. To support the development of embedded applications using Erlang we want to provide Erlang and Embedded developers with a run-time system suited for embedded devices. We have managed to shrink the disk size of the Erlang runtime sy...

Optical spectroscopy in channel waveguides made in Nd:YAG crystals by femtosecond laser writing

International Nuclear Information System (INIS)

Torchia, G.A.; Mendez, C.; Roso, L.; Tocho, J.O.

2008-01-01

In this work, we present an optical characterization of channel waveguides fabricated by means of femtosecond laser writing on Nd:YAG substrates. These guiding structures show a refractive index increment of about 1x10 -3 which allows TE propagation. By pumping with a CW solid-state laser at 532 nm reaching the 2 G 9/2 and 4 G 7/2 manifolds of Nd 3+ ions, we have explored the emission band corresponding to 4 F 3/2 → 4 I 9/2 optical transitions (peaked at 890 nm). From data, we have found that emission showed similar characteristics for waveguide and bulk. On the other hand, the lifetime corresponding to the 4 F 3/2 metaestable level was determined to be 240 μs for bulk and waveguide. Summarizing, we have made suitable channel waveguides in Nd:YAG crystals, by fs interaction, with similar spectroscopic properties to those of the bulk, a fact that boosters the photonics application of these devices. For the first time to our knowledge, a direct index increment waveguide made by interaction with ultra-short intense pulses in YAG crystals has been performed. This fabrication procedure can be an efficient tool to make several optical circuits in active materials by means of the one-step, fast and low-cost processing

Optical Control of Intersubband Absorption in a Multiple Quantum Well-Embedded Semiconductor Microcravity

Science.gov (United States)

Liu, Ansheng; Ning, Cun-Zheng

2000-01-01

Optical intersubband response of a multiple quantum well (MQW)-embedded microcavity driven by a coherent pump field is studied theoretically. The n-type doped MQW structure with three subbands in the conduction band is sandwiched between a semi-infinite medium and a distributed Bragg reflector (DBR). A strong pump field couples the two upper subbands and a weak field probes the two lower subbands. To describe the optical response of the MQW-embedded microcavity, we adopt a semi-classical nonlocal response theory. Taking into account the pump-probe interaction, we derive the probe-induced current density associated with intersubband transitions from the single-particle density-matrix formalism. By incorporating the current density into the Maxwell equation, we solve the probe local field exactly by means of Green's function technique and the transfer-matrix method. We obtain an exact expression for the probe absorption coefficient of the microcavity. For a GaAs/Al(sub x)Ga(sub 1-x)As MQW structure sandwiched between a GaAs/AlAs DBR and vacuum, we performed numerical calculations of the probe absorption spectra for different parameters such as pump intensity, pump detuning, and cavity length. We find that the probe spectrum is strongly dependent on these parameters. In particular, we find that the combination of the cavity effect and the Autler-Townes effect results in a triplet in the optical spectrum of the MQW system. The optical absorption peak value and its location can be feasibly controlled by varying the pump intensity and detuning.

Femtosecond laser direct-write of optofluidics in polymer-coated optical fiber

Science.gov (United States)

Joseph, Kevin A. J.; Haque, Moez; Ho, Stephen; Aitchison, J. Stewart; Herman, Peter R.

2017-03-01

Multifunctional lab in fiber technology seeks to translate the accomplishments of optofluidic, lab on chip devices into silica fibers. a robust, flexible, and ubiquitous optical communication platform that can underpin the `Internet of Things' with distributed sensors, or enable lab on chip functions deep inside our bodies. Femtosecond lasers have driven significant advances in three-dimensional processing, enabling optical circuits, microfluidics, and micro-mechanical structures to be formed around the core of the fiber. However, such processing typically requires the stripping and recoating of the polymer buffer or jacket, increasing processing time and mechanically weakening the device. This paper reports on a comprehensive assessment of laser damage in urethane-acrylate-coated fiber. The results show a sufficient processing window is available for femtosecond laser processing of the fiber without damaging the polymer jacket. The fiber core, cladding, and buffer could be simultaneously processed without removal of the buffer jacket. Three-dimensional lab in fiber devices were successfully fabricated by distortion-free immersionlens focusing, presenting fiber-cladding optical circuits and progress towards chemically-etched channels, microfluidic cavities, and MEMS structure inside buffer-coated fiber.

Encapsulation of Polymer Colloids in a Sol-Gel Matrix. Direct-Writing of Coassembling Organic-Inorganic Hybrid Photonic Crystals.

Science.gov (United States)

Mikosch, Annabel; Kuehne, Alexander J C

2016-03-22

The spontaneous self-assembly of polymer colloids into ordered arrangements provides a facile strategy for the creation of photonic crystals. However, these structures often suffer from defects and insufficient cohesion, which result in flaking and delamination from the substrate. A coassembly process has been developed for convective assembly, resulting in large-area encapsulated colloidal crystals. However, to generate patterns or discrete deposits in designated places, convective assembly is not suitable. Here we experimentally develop conditions for direct-writing of coassembling monodisperse dye-doped polystyrene particles with a sol-gel precursor to form solid encapsulated photonic crystals. In a simple procedure the colloids are formulated in a sol-gel precursor solution, drop-cast on a flat substrate, and dried. We here establish the optimal parameters to form reproducible highly ordered photonic crystals with good optical performance. The obtained photonic crystals interact with light in the visible spectrum with a narrow optical stop-gap.

Column generation algorithms for virtual network embedding in flexi-grid optical networks.

Science.gov (United States)

Lin, Rongping; Luo, Shan; Zhou, Jingwei; Wang, Sheng; Chen, Bin; Zhang, Xiaoning; Cai, Anliang; Zhong, Wen-De; Zukerman, Moshe

2018-04-16

Network virtualization provides means for efficient management of network resources by embedding multiple virtual networks (VNs) to share efficiently the same substrate network. Such virtual network embedding (VNE) gives rise to a challenging problem of how to optimize resource allocation to VNs and to guarantee their performance requirements. In this paper, we provide VNE algorithms for efficient management of flexi-grid optical networks. We provide an exact algorithm aiming to minimize the total embedding cost in terms of spectrum cost and computation cost for a single VN request. Then, to achieve scalability, we also develop a heuristic algorithm for the same problem. We apply these two algorithms for a dynamic traffic scenario where many VN requests arrive one-by-one. We first demonstrate by simulations for the case of a six-node network that the heuristic algorithm obtains very close blocking probabilities to exact algorithm (about 0.2% higher). Then, for a network of realistic size (namely, USnet) we demonstrate that the blocking probability of our new heuristic algorithm is about one magnitude lower than a simpler heuristic algorithm, which was a component of an earlier published algorithm.

Femtosecond Laser Structuring in Optical Fiber and Transparent Films

Directory of Open Access Journals (Sweden)

Herman Peter R.

2013-11-01

Full Text Available Femtosecond laser processing is optimized for writing optical circuits, optical resonators, and microfluidic devices inside the cladding of single-mode optical fiber that couple efficiently with the fiber core waveguide. The laser processes open new directions towards Labon-a-Fiber.

Direct Metal Writing and Precise Positioning of Gold Nanoparticles within Microfluidic Channels for SERS Sensing of Gaseous Analytes.

Science.gov (United States)

Lee, Mian Rong; Lee, Hiang Kwee; Yang, Yijie; Koh, Charlynn Sher Lin; Lay, Chee Leng; Lee, Yih Hong; Phang, In Yee; Ling, Xing Yi

2017-11-15

We demonstrate a one-step precise direct metal writing of well-defined and densely packed gold nanoparticle (AuNP) patterns with tunable physical and optical properties. We achieve this by using two-photon lithography on a Au precursor comprising poly(vinylpyrrolidone) (PVP) and ethylene glycol (EG), where EG promotes higher reduction rates of Au(III) salt via polyol reduction. Hence, clusters of monodisperse AuNP are generated along raster scanning of the laser, forming high-particle-density, well-defined structures. By varying the PVP concentration, we tune the AuNP size from 27.3 to 65.0 nm and the density from 172 to 965 particles/μm 2 , corresponding to a surface roughness of 12.9 to 67.1 nm, which is important for surface-based applications such as surface-enhanced Raman scattering (SERS). We find that the microstructures exhibit an SERS enhancement factor of >10 5 and demonstrate remote writing of well-defined Au microstructures within a microfluidic channel for the SERS detection of gaseous molecules. We showcase in situ SERS monitoring of gaseous 4-methylbenzenethiol and real-time detection of multiple small gaseous species with no specific affinity to Au. This one-step, laser-induced fabrication of AuNP microstructures ignites a plethora of possibilities to position desired patterns directly onto or within most surfaces for the future creation of multifunctional lab-on-a-chip devices.

Fabrication of computer-generated holograms using femtosecond laser direct writing.

Science.gov (United States)

Berlich, René; Richter, Daniel; Richardson, Martin; Nolte, Stefan

2016-04-15

We demonstrate a single-step fabrication method for computer-generated holograms based on femtosecond laser direct writing. Therefore, a tightly arranged longitudinal waveguide array is directly inscribed into a transparent material. By tailoring the individual waveguide length, the phase profile of an incident laser beam can be arbitrarily adapted. The approach is verified in common borosilicate glass by inscribing a designed phase hologram, which forms the desired intensity pattern in its far field. The resulting performance is analyzed, and the potential as well as limitations of the method are discussed.

Estimation of line dimensions in 3D direct laser writing lithography

International Nuclear Information System (INIS)

Guney, M G; Fedder, G K

2016-01-01

Two photon polymerization (TPP) based 3D direct laser writing (3D-DLW) finds application in a wide range of research areas ranging from photonic and mechanical metamaterials to micro-devices. Most common structures are either single lines or formed by a set of interconnected lines as in the case of crystals. In order to increase the fidelity of these structures and reach the ultimate resolution, the laser power and scan speed used in the writing process should be chosen carefully. However, the optimization of these writing parameters is an iterative and time consuming process in the absence of a model for the estimation of line dimensions. To this end, we report a semi-empirical analytic model through simulations and fitting, and demonstrate that it can be used for estimating the line dimensions mostly within one standard deviation of the average values over a wide range of laser power and scan speed combinations. The model delimits the trend in onset of micro-explosions in the photoresist due to over-exposure and of low degree of conversion due to under-exposure. The model guides setting of high-fidelity and robust writing parameters of a photonic crystal structure without iteration and in close agreement with the estimated line dimensions. The proposed methodology is generalizable by adapting the model coefficients to any 3D-DLW setup and corresponding photoresist as a means to estimate the line dimensions for tuning the writing parameters. (paper)

Direct writing and electro-mechanical characterization of Ag micro-patterns on polymer substrates for flexible electronics

International Nuclear Information System (INIS)

Torres Arango, Maria A.; Cokeley, Anna M.; Beard, Jared J.; Sierros, Konstantinos A.

2015-01-01

There is currently a great interest in developing flexible electrodes. Such components are used in most electronic devices from displays to solar cells to flexible sensors. To date most of them are fabricated using expensive vacuum techniques, and are based on transparent conducting oxides. These oxides are not entirely compatible with flexible substrates under the application of mechanical stresses, due to their brittle nature. Therefore, there is a need to explore novel low-cost, large-area fabrication methods to deposit alternative conducting materials with enhanced electro-mechanical performance. This work focuses on Ag patterns fabricated at low temperatures (below 150 °C) on flexible polyethylene naphthalate utilizing a robotic printing approach. Such lithography-free method minimizes material waste by printing exact amounts of inks on digitally predefined locations. Additionally, it allows a broad feature size range, from a few μm to a few mm, and a variety of ink viscosities for better pattern control. We investigate the synthesis and direct writing of Ag particle-based inks, patterned-on-flex as lines and grids in the μm scale. We report on a high-yield ink synthesis method (~ 61.6%) with controlled particle size. It is found that the electrical resistivity (1.75 ∗ 10"−"4 Ω cm) of the patterns is in the same range with similar particle-based conductive components. The correlation between annealing temperature, microstructural evolution, and electrical performance is established. Also, the optical transmittance of the patterns can be controlled to meet specific application requirements by regulating the substrate surface area covered. Finally, the mechanical behavior under both monotonic and cyclic conditions shows a superior performance compared to brittle counterparts and underlines the potential of such metallic micro-patterns to be utilized in a wide range of flexible electronic applications. It is believed that direct writing of Ag patterns on

Direct writing and electro-mechanical characterization of Ag micro-patterns on polymer substrates for flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Torres Arango, Maria A.; Cokeley, Anna M.; Beard, Jared J.; Sierros, Konstantinos A., E-mail: kostas.sierros@mail.wvu.edu

2015-12-01

There is currently a great interest in developing flexible electrodes. Such components are used in most electronic devices from displays to solar cells to flexible sensors. To date most of them are fabricated using expensive vacuum techniques, and are based on transparent conducting oxides. These oxides are not entirely compatible with flexible substrates under the application of mechanical stresses, due to their brittle nature. Therefore, there is a need to explore novel low-cost, large-area fabrication methods to deposit alternative conducting materials with enhanced electro-mechanical performance. This work focuses on Ag patterns fabricated at low temperatures (below 150 °C) on flexible polyethylene naphthalate utilizing a robotic printing approach. Such lithography-free method minimizes material waste by printing exact amounts of inks on digitally predefined locations. Additionally, it allows a broad feature size range, from a few μm to a few mm, and a variety of ink viscosities for better pattern control. We investigate the synthesis and direct writing of Ag particle-based inks, patterned-on-flex as lines and grids in the μm scale. We report on a high-yield ink synthesis method (~ 61.6%) with controlled particle size. It is found that the electrical resistivity (1.75 ∗ 10{sup −4} Ω cm) of the patterns is in the same range with similar particle-based conductive components. The correlation between annealing temperature, microstructural evolution, and electrical performance is established. Also, the optical transmittance of the patterns can be controlled to meet specific application requirements by regulating the substrate surface area covered. Finally, the mechanical behavior under both monotonic and cyclic conditions shows a superior performance compared to brittle counterparts and underlines the potential of such metallic micro-patterns to be utilized in a wide range of flexible electronic applications. It is believed that direct writing of Ag patterns

Fabrication of submicron proteinaceous structures by direct laser writing

Energy Technology Data Exchange (ETDEWEB)

Serien, Daniela [Center for International Research on Integrative Biomedical Systems, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505 Tokyo (Japan); Takeuchi, Shoji, E-mail: takeuchi@iis.u-tokyo.ac.jp [Center for International Research on Integrative Biomedical Systems, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505 Tokyo (Japan); ERATO Takeuchi Biohybrid Innovation Project, Japan Science and Technology Agency, 4-6-1 Komaba, Meguro-ku, 153-8505 Tokyo (Japan)

2015-07-06

In this paper, we provide a characterization of truly free-standing proteinaceous structures with submicron feature sizes depending on the fabrication conditions by model-based analysis. Protein cross-linking of bovine serum albumin is performed by direct laser writing and two-photon excitation of flavin adenine dinucleotide. We analyze the obtainable fabrication resolution and required threshold energy for polymerization. The applied polymerization model allows prediction of fabrication conditions and resulting fabrication size, alleviating the application of proteinaceous structure fabrication.

Fabrication of three-dimensional polymer quadratic nonlinear grating structures by layer-by-layer direct laser writing technique

Science.gov (United States)

Bich Do, Danh; Lin, Jian Hung; Diep Lai, Ngoc; Kan, Hung-Chih; Hsu, Chia Chen

2011-08-01

We demonstrate the fabrication of a three-dimensional (3D) polymer quadratic nonlinear (χ(2)) grating structure. By performing layer-by-layer direct laser writing (DLW) and spin-coating approaches, desired photobleached grating patterns were embedded in the guest--host dispersed-red-1/poly(methylmethacrylate) (DR1/PMMA) active layers of an active-passive alternative multilayer structure through photobleaching of DR1 molecules. Polyvinyl-alcohol and SU8 thin films were deposited between DR1/PMMA layers serving as a passive layer to separate DR1/PMMA active layers. After applying the corona electric field poling to the multilayer structure, nonbleached DR1 molecules in the active layers formed polar distribution, and a 3D χ(2) grating structure was obtained. The χ(2) grating structures at different DR1/PMMA nonlinear layers were mapped by laser scanning second harmonic (SH) microscopy, and no cross talk was observed between SH images obtained from neighboring nonlinear layers. The layer-by-layer DLW technique is favorable to fabricating hierarchical 3D polymer nonlinear structures for optoelectronic applications with flexible structural design.

We learn to write by reading, but writing can make you smarter We learn to write by reading, but writing can make you smarter

Directory of Open Access Journals (Sweden)

Stephen Krashen

2008-04-01

Full Text Available My goal in this paper is to make Iwo points: Writing style does not come from writing or from direct instruction, but from reading. Actual writing can help us solve problems and can make us smarter. Writing Style Comes from Readino, A substantial amount of research strongly suggests that we learn to write by reading. To be more precise, we acquire writing style, the special language of writing, by reading. Hypothesizing that writing style comes from reading, not from writing or instniction, is consistent with what is known about language acquisition: Most of language acquisition lakes place subconsciously, not through deliberate study, and it is a result of input (comprehension, not output (production (Krashen, 1982. My goal in this paper is to make Iwo points: Writing style does not come from writing or from direct instruction, but from reading. Actual writing can help us solve problems and can make us smarter. Writing Style Comes from Readino, A substantial amount of research strongly suggests that we learn to write by reading. To be more precise, we acquire writing style, the special language of writing, by reading. Hypothesizing that writing style comes from reading, not from writing or instniction, is consistent with what is known about language acquisition: Most of language acquisition lakes place subconsciously, not through deliberate study, and it is a result of input (comprehension, not output (production (Krashen, 1982.

Dewetting of thin films on flexible substrates via direct-write laser exposure

Science.gov (United States)

Ferrer, Anthony Jesus

Microelectromechanical systems (MEMS) have enabled a wide variety of technologies both in the consumer space and in industrial/research areas. At the market level, such devices advance by the invention and innovation of production techniques. Additionally, there has been increased demand for flexible versions of such MEMS devices. Thin film patterning, represents a key technology for the realization of such flexible electronics. Patterns and methods that can be directly written into the thin film allow for design modification on the fly with the need for harsh chemicals and long etching steps. Laser-induced dewetting has the potential to create patterns in thin films at both the microscopic and nanoscopic level without wasting deposited material. This thesis presents the first demonstration of high-speed direct-write patterning of metallic thin films that uses a laser-induced dewetting phenomenon to prevent material loss. The ability to build film material with this technique is explored using various scanning geometries. Finally, demonstrations of direct-write dewetting of a variety of thin films will be presented with special consideration for high melting point metals deposited upon polymer substrates.

Multi-axial strain transfer from laminated CFRP composites to embedded Bragg sensor: I. Parametric study

International Nuclear Information System (INIS)

Luyckx, G; Voet, E; De Waele, W; Degrieck, J

2010-01-01

Embedded optical fibre sensors are considered in numerous applications for structural health monitoring purposes. However, since the optical fibre and the host material in which it is embedded, will have different material properties, strain in both materials will not be equal when load is applied. Therefore, the multi-axial strain transfer from the host material to the embedded sensor (optical fibre) has to be considered in detail. In the first part of this paper the strain transfer will be determined using finite element modelling of a circular isotropic glass fibre embedded first in an isotropic host and second in an anisotropic composite material. The strain transfer or relation depends on the mechanical properties of the host material and the sensor (Young's modulus and Poisson's ratio), on the lay-up of the composite material (uni-directional lay-up/cross-ply lay-up) and the position of the sensor in a certain layer. In the second part of the paper the developed strain transfer model will be evaluated for one specific lay-up and sensor type

Crosstalk-aware virtual network embedding over inter-datacenter optical networks with few-mode fibers

Science.gov (United States)

Huang, Haibin; Guo, Bingli; Li, Xin; Yin, Shan; Zhou, Yu; Huang, Shanguo

2017-12-01

Virtualization of datacenter (DC) infrastructures enables infrastructure providers (InPs) to provide novel services like virtual networks (VNs). Furthermore, optical networks have been employed to connect the metro-scale geographically distributed DCs. The synergistic virtualization of the DC infrastructures and optical networks enables the efficient VN service over inter-DC optical networks (inter-DCONs). While the capacity of the used standard single-mode fiber (SSMF) is limited by their nonlinear characteristics. Thus, mode-division multiplexing (MDM) technology based on few-mode fibers (FMFs) could be employed to increase the capacity of optical networks. Whereas, modal crosstalk (XT) introduced by optical fibers and components deployed in the MDM optical networks impacts the performance of VN embedding (VNE) over inter-DCONs with FMFs. In this paper, we propose a XT-aware VNE mechanism over inter-DCONs with FMFs. The impact of XT is considered throughout the VNE procedures. The simulation results show that the proposed XT-aware VNE can achieves better performances of blocking probability and spectrum utilization compared to conventional VNE mechanisms.

Giant nonlinear interaction between two optical beams via a quantum dot embedded in a photonic wire

DEFF Research Database (Denmark)

Nguyen, H.A.; Grange, T.; Reznychenko, B.

2018-01-01

a tailored photonic environment. Here, we demonstrate a two-mode giant nonlinearity with a single semiconductor quantum dot (QD) embedded in a photonic wire antenna. We exploit two detuned optical transitions associated with the exciton-biexciton QD level scheme. Owing to the broadband waveguide antenna...

Gelatin-based laser direct-write technique for the precise spatial patterning of cells.

Science.gov (United States)

Schiele, Nathan R; Chrisey, Douglas B; Corr, David T

2011-03-01

Laser direct-writing provides a method to pattern living cells in vitro, to study various cell-cell interactions, and to build cellular constructs. However, the materials typically used may limit its long-term application. By utilizing gelatin coatings on the print ribbon and growth surface, we developed a new approach for laser cell printing that overcomes the limitations of Matrigel™. Gelatin is free of growth factors and extraneous matrix components that may interfere with cellular processes under investigation. Gelatin-based laser direct-write was able to successfully pattern human dermal fibroblasts with high post-transfer viability (91% ± 3%) and no observed double-strand DNA damage. As seen with atomic force microscopy, gelatin offers a unique benefit in that it is present temporarily to allow cell transfer, but melts and is removed with incubation to reveal the desired application-specific growth surface. This provides unobstructed cellular growth after printing. Monitoring cell location after transfer, we show that melting and removal of gelatin does not affect cellular placement; cells maintained registry within 5.6 ± 2.5 μm to the initial pattern. This study demonstrates the effectiveness of gelatin in laser direct-writing to create spatially precise cell patterns with the potential for applications in tissue engineering, stem cell, and cancer research.

10,000 optical write, read, and erase cycles in an azobenzene sidechain liquid-crystalline polyester

DEFF Research Database (Denmark)

Holme, NCR; Ramanujam, P.S.; Hvilsted, Søren

1996-01-01

We show far what is believed to he the first time that it is possible tu generate 10,000 rapid write, read, and erase cycles optically in an azobenzene sidechain liquid-crystalline polyester. We do this by exposing the film alternately to visible light from an argon laser at 488 nm and ultraviolet...

The art of programming embedded systems

CERN Document Server

Ganssle, Jack

1992-01-01

Embedded systems are products such as microwave ovens, cars, and toys that rely on an internal microprocessor. This book is oriented toward the design engineer or programmer who writes the computer code for such a system. There are a number of problems specific to the embedded systems designer, and this book addresses them and offers practical solutions.Key Features* Offers cookbook routines, algorithms, and design techniques* Includes tips for handling debugging management and testing* Explores the philosophy of tightly coupling software and hardware in programming and dev

Surface patterned dielectrics by direct writing of anodic oxides using scanning droplet cell microscopy

International Nuclear Information System (INIS)

Siket, Christian M.; Mardare, Andrei Ionut; Kaltenbrunner, Martin; Bauer, Siegfried; Hassel, Achim Walter

2013-01-01

Highlights: • Scanning droplet cell microscopy was applied for local gate oxide writing. • Sharp lines are obtained at the highest writing speed of 1 mm min −1 . • 13.4 kC cm −3 was found as charge per volume for aluminium oxide. • High field constant of 24 nm V −1 and dielectric constant of 12 were determined for Al 2 O 3 by CV and EIS. -- Abstract: Scanning droplet cell microscopy was used for patterning of anodic oxide lines on the surface of Al thin films by direct writing. The structural modifications of the written oxide lines as a function of the writing speed were studied by analyzing the relative error of the line widths. Sharper lines were obtained for writing speeds faster than 1 mm min −1 . An increase in sharpness was observed for higher writing speeds. A theoretical model based on the Faraday law is proposed to explain the constant anodisation current measured during the writing process and yielded a charge per volume of 13.4 kC cm −3 for Al 2 O 3 . From calculated oxide film thicknesses the high field constant was found to be 24 nm V −1 . Electrochemical impedance spectroscopy revealed an increase of the electrical permittivity up to ε = 12 with the decrease of the writing speed of the oxide line. Writing of anodic oxide lines was proven to be an important step in preparing capacitors and gate dielectrics in plastic electronics

Embedded Fiber Optic Sensors for Measuring Transient Detonation/Shock Behavior;Time-of-Arrival Detection and Waveform Determination.

Energy Technology Data Exchange (ETDEWEB)

Chavez, Marcus Alexander; Willis, Michael David; Covert, Timothy Todd

2014-09-01

The miniaturization of explosive components has driven the need for a corresponding miniaturization of the current diagnostic techniques available to measure the explosive phenomena. Laser interferometry and the use of spectrally coated optical windows have proven to be an essential interrogation technique to acquire particle velocity time history data in one- dimensional gas gun and relatively large-scale explosive experiments. A new diagnostic technique described herein allows for experimental measurement of apparent particle velocity time histories in microscale explosive configurations and can be applied to shocks/non-shocks in inert materials. The diagnostic, Embedded Fiber Optic Sensors (EFOS), has been tested in challenging microscopic experimental configurations that give confidence in the technique's ability to measure the apparent particle velocity time histories of an explosive with pressure outputs in the tenths of kilobars to several kilobars. Embedded Fiber Optic Sensors also allow for several measurements to be acquired in a single experiment because they are microscopic, thus reducing the number of experiments necessary. The future of EFOS technology will focus on further miniaturization, material selection appropriate for the operating pressure regime, and extensive hydrocode and optical analysis to transform apparent particle velocity time histories into true particle velocity time histories as well as the more meaningful pressure time histories.

Silver Nanowire Embedded Colorless Polyimide Heater for Wearable Chemical Sensors: Improved Reversible Reaction Kinetics of Optically Reduced Graphene Oxide.

Science.gov (United States)

Choi, Seon-Jin; Kim, Sang-Joon; Jang, Ji-Soo; Lee, Ji-Hyun; Kim, Il-Doo

2016-09-14

Optically reduced graphene oxide (ORGO) sheets are successfully integrated on silver nanowire (Ag NW)-embedded transparent and flexible substrate. As a heating element, Ag NWs are embedded in a colorless polyimide (CPI) film by covering Ag NW networks using polyamic acid and subsequent imidization. Graphene oxide dispersed aqueous solution is drop-coated on the Ag NW-embedded CPI (Ag NW-CPI) film and directly irradiated by intense pulsed light to obtain ORGO sheets. The heat generation property of Ag NW-CPI film is investigated by applying DC voltage, which demonstrates unprecedentedly reliable and stable characteristics even in dynamic bending condition. To demonstrate the potential application in wearable chemical sensors, NO 2 sensing characteristic of ORGO is investigated with respect to the different heating temperature (22.7-71.7 °C) of Ag NW-CPI film. The result reveals that the ORGO sheets exhibit high sensitivity of 2.69% with reversible response/recovery sensing properties and minimal deviation of baseline resistance of around 1% toward NO 2 molecules when the temperature of Ag NW-CPI film is 71.7 °C. This work first demonstrates the improved reversible NO 2 sensing properties of ORGO sheets on flexible and transparent Ag NW-CPI film assisted by Ag NW heating networks. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct Write Printing on Thin and Flexible Substrates for Space Applications

Science.gov (United States)

Paquette, Beth

2016-01-01

This presentation describes the work done on direct-write printing conductive traces for a flexible detector application. A Repeatability Plan was established to define detector requirements, material and printer selections, printing facilities, and tests to verify requirements are met. Designs were created for the detector, and printed using an aerosol jet printer. Testing for requirement verification is ongoing.

Development of Embedded Fiber-Optic Evanescent Wave Sensors for Optical Characterization of Graphite Anodes in Lithium-Ion Batteries.

Science.gov (United States)

Ghannoum, AbdulRahman; Nieva, Patricia; Yu, Aiping; Khajepour, Amir

2017-11-29

The development, fabrication, and embedment of fiber-optic evanescent wave sensors (FOEWSs) to monitor the state of charge (SOC) and the state of health (SOH) of lithium-ion batteries (LIBs) are presented. Etching of FOEWSs is performed using a solution of 40 wt % ammonium fluoride (NH 4 F) and 49 wt % hydrofluoric acid (HF) (6:1), which is found to be superior to an etching solution containing just 49 wt % HF. FOEWSs were characterized using glycerol and found to have the highest sensitivity in a lithium-ion battery when they lose 92% of their transmittance in the presence of glycerol on their sensing region. The physical effect that the FOEWS has on the graphite anode is also investigated and is found to be much more significant in Swagelok cells compared to that in in-house-fabricated pouch cells, mainly due to pressure variation. The FOEWS was found to be most sensitive to the changes in the LIB when it was completely embedded using a slurry of graphite anode material within a pouch cell. The optimized fabrication process of the embedded FOEWS demonstrates the potential of using such sensors commercially for real-time monitoring of the SOC and SOH of LIBs while in operation.

Higher-resolution selective metallization on alumina substrate by laser direct writing and electroless plating

International Nuclear Information System (INIS)

Lv, Ming; Liu, Jianguo; Wang, Suhuan; Ai, Jun; Zeng, Xiaoyan

2016-01-01

Graphical abstract: - Highlights: • Mechanisms of laser direct writing and electroless plating were studied. • Active seeds in laser-irradiated zone and laser-affected zone were found to be different. • A special chemical cleaning method with aqua regia was taken. • Higher-resolution copper patterns on alumina ceramic were obtained conveniently. - Abstract: How to fabricate conductive patterns on ceramic boards with higher resolution is a challenge in the past years. The fabrication of copper patterns on alumina substrate by laser direct writing and electroless copper plating is a low cost and high efficiency method. Nevertheless, the lower resolution limits its further industrial applications in many fields. In this report, the mechanisms of laser direct writing and electroless copper plating were studied. The results indicated that as the decomposed products of precursor PdCl_2 have different chemical states respectively in laser-irradiated zone (LIZ) and laser-affected zone (LAZ). This phenomenon was utilized and a special chemical cleaning method with aqua regia solution was taken to selectively remove the metallic Pd in LAZ, while kept the PdO in LIZ as the only active seeds. As a result, the resolution of subsequent copper patterns was improved significantly. This technique has a great significance to develop the microelectronics devices.

Fabrication of amplitude-phase type diffractive optical elements in aluminium films

Science.gov (United States)

Fomchenkov, S. A.; Butt, M. A.

2017-11-01

In the course of studies have been conducted a method of forming the phase diffractive optical elements (DOEs) by direct laser writing in thin films of aluminum. The quality of the aluminum films were investigated depending on the parameters of magnetron sputtering process. Moreover, the parameters of the laser writing process in thin films of aluminum were optimized. The structure of phase diffractive optical elements was obtained by the proposed method.

Final Report for Grant "Direct Writing via Novel Aromatic Ladder Polymer Precursors"

Energy Technology Data Exchange (ETDEWEB)

C. B. Gorman

2010-10-29

This report describes activities and findings under the above entitled grant. These pertain to the development of new synthetic routes to novel precursor polymers and oligomers that are applicable for conversion from electrical insulators to electrical conductors under the application of light (e.g. direct photolithographic writing)

Embedding Multiple Literacies into STEM Curricula

Science.gov (United States)

Soules, Aline; Nielsen, Sarah; LeDuc, Danika; Inouye, Caron; Singley, Jason; Wildy, Erica; Seitz, Jeff

2014-01-01

In fall 2012, an interdisciplinary team of science, English, and library faculty embedded reading, writing, and information literacy strategies in Science, Technology, Engineering, and Mathematics (STEM) curricula as a first step in improving student learning and retention in science courses and aligning them with the Next Generation Science and…

Competition of Faraday rotation and birefringence in femtosecond laser direct written waveguides in magneto-optical glass.

Science.gov (United States)

Liu, Qiang; Gross, S; Dekker, P; Withford, M J; Steel, M J

2014-11-17

We consider the process of Faraday rotation in femtosecond laser direct-write waveguides. The birefringence commonly associated with such waveguides may be expected to impact the observable Faraday rotation. Here, we theoretically calculate and experimentally verify the competition between Faraday rotation and birefringence in two waveguides created by laser writing in a commercial magneto-optic glass. The magnetic field applied to induce Faraday rotation is nonuniform, and as a result, we find that the two effects can be clearly separated and used to accurately determine even weak birefringence. The birefringence in the waveguides was determined to be on the scale of Δn = 10(-6) to 10(-5). The reduction in Faraday rotation caused by birefringence of order Δn = 10(-6) was moderate and we obtained approximately 9° rotation in an 11 mm waveguide. In contrast, for birefringence of order 10(-5), a significant reduction in the polarization azimuth change was found and only 6° rotation was observed.

Playwright meets career coach : writing dialogues to promote awareness and self-direction

NARCIS (Netherlands)

Reinekke Lengelle; dr. Frans Meijers

2015-01-01

In this chapter we propose that writing dialogues in creative, expressive, and reflective ways can foster more awareness and self-direction among those who aim to start, build, or rescue their careers. In the first section of the chapter we sketch the societal issues for which narrative counselling

Composition Medium Comparability in a Direct Writing Assessment of Non-Native English Speakers

Directory of Open Access Journals (Sweden)

Edward W. Wolfe

2004-01-01

Full Text Available The Test of English as a Foreign Language (TOEFL contains a direct writing assessment, and examinees are given the option of composing their responses at a computer terminal using a keyboard or composing their responses in handwriting. This study sought to determine whether performance on a direct writing assessment is comparable for examinees when given the choice to compose essays in handwriting versus word processing. We examined this relationship controlling for English language proficiency and several demographic characteristics of examinees using linear models. We found a weak two-way interaction between composition medium and English language proficiency with examinees with weaker English language scores performing better on handwritten essays while examinees with better English language scores performing comparably on the two testing media. We also observed predictable differences associated with geographic region, native language, gender, and age.

Optical polarization studies of Herbig-Haro objects. Pt. 7

International Nuclear Information System (INIS)

Scarrott, S.M.; Gledhill, T.M.; Rolph, C.D.

1990-01-01

A small patch of optical nebulosity in the cometary globule CG30 is an amorphous reflection nebula containing a Herbig-Haro knot. The exciting and illuminating star, which we identify with the IR source IRAS 08076-3356/CG30IRS4, is deeply embedded in the globule and is not seen directly at optical wavelengths. Structure in the polarization data suggests that the optical nebula is formed by the illumination of the walls of a cavity excavated in the cloud during outflow activity from the embedded source. (author)

Direct-write fabrication of a nanoscale digital logic element on a single nanowire

International Nuclear Information System (INIS)

Roy, Somenath; Gao Zhiqiang

2010-01-01

In this paper we report on the 'direct-write' fabrication and electrical characteristics of a nanoscale logic inverter, integrating enhancement-mode (E-mode) and depletion-mode (D-mode) field-effect transistors (FETs) on a single zinc oxide (ZnO) nanowire. 'Direct-writing' of platinum metal electrodes and a dielectric layer is executed on individual single-crystalline ZnO nanowires using either a focused electron beam (FEB) or a focused ion beam (FIB). We fabricate a top-gate FET structure, in which the gate electrode wraps around the ZnO nanowire, resulting in a more efficient gate response than the conventional back-gate nanowire transistors. For E-mode device operation, the gate electrode (platinum) is deposited directly onto the ZnO nanowire by a FEB, which creates a Schottky barrier and in turn a fully depleted channel. Conversely, sandwiching an insulating layer between the FIB-deposited gate electrode and the nanowire channel makes D-mode operation possible. Integrated E- and D-mode FETs on a single nanowire exhibit the characteristics of a direct-coupled FET logic (DCFL) inverter with a high gain and noise margin.

Fabrication of optical devices in poly(dimethylsiloxane) by proton microbeam

International Nuclear Information System (INIS)

Huszank, R.; Szilasi, S.Z.; Rajta, I.; Csik, A.

2009-01-01

Complete text of publication follows. Optical diffraction grating and micro Fresnel zone plate type structures were fabricated in relatively thin poly(dimethylsiloxane) (PDMS) layers using proton beam writing technique and the performance of these optical devices was tested. Micro-optics is a key technology in many fields of common applications like, for example, data communication, lighting technology, industrial automation, display technology, sensing applications and data storage. It enables new functionalities and applications previously inaccessible and improves performance of the already available products with reduced cost, volume and weight. There are a few different fabrication techniques to produce refractive or diffractive micro-optical devices such as X-ray lithography, UV-lithography, e-beam lithography, laser writing, plasma etching, proton beam writing. In general, three different kinds of materials are used for micro-optics, such as glass, polymers and crystal. PDMS is a commonly used silicon-based organic polymer, optically clear, generally considered to be inert, non-toxic and biocompatible and it has been used as a resist material for direct write techniques only in very few cases. In this work, PDMS was used as a resist material; the structures were irradiated directly into the polymer. We were looking for a biocompatible, micropatternable polymer in which the chemical structure changes significantly due to proton beam exposure making the polymer capable of proton beam writing. We demonstrated that the change in the structure of the polymer is so significant that there is no need to perform any development processes. The proton irradiation causes refractive index change in the polymer, so diffraction gratings and other optical devices like Fresnel zone plates can be fabricated in this way. The observed high order diffraction patterns prove the high quality of the created optical devices [1]. This technique may be a useful tool for designing

Engineering fluidic delays in paper-based devices using laser direct-writing.

Science.gov (United States)

He, P J W; Katis, I N; Eason, R W; Sones, C L

2015-10-21

We report the use of a new laser-based direct-write technique that allows programmable and timed fluid delivery in channels within a paper substrate which enables implementation of multi-step analytical assays. The technique is based on laser-induced photo-polymerisation, and through adjustment of the laser writing parameters such as the laser power and scan speed we can control the depth and/or the porosity of hydrophobic barriers which, when fabricated in the fluid path, produce controllable fluid delay. We have patterned these flow delaying barriers at pre-defined locations in the fluidic channels using either a continuous wave laser at 405 nm, or a pulsed laser operating at 266 nm. Using this delay patterning protocol we generated flow delays spanning from a few minutes to over half an hour. Since the channels and flow delay barriers can be written via a common laser-writing process, this is a distinct improvement over other methods that require specialist operating environments, or custom-designed equipment. This technique can therefore be used for rapid fabrication of paper-based microfluidic devices that can perform single or multistep analytical assays.

Strain monitoring of a newly developed precast concrete track for high speed railway traffic using embedded fiber optic sensors

Science.gov (United States)

Crail, Stephanie; Reichel, D.; Schreiner, U.; Lindner, E.; Habel, Wolfgang R.; Hofmann, Detlef; Basedau, Frank; Brandes, K.; Barner, A.; Ecke, Wolfgang; Schroeder, Kerstin

2002-07-01

In a German slab track system (Feste Fahrbahn FF, system Boegl) for speeds up to 300 km/h and more different fiber optic sensors have been embedded in several levels and locations of the track system. The track system consists of prestressed precast panels of steel fiber concrete which are supported by a cat-in-situ concrete or asphalt base course. The sensors are to measure the bond behavior or the stress transfer in the track system. For that, tiny fiber-optic sensors - fiber Fabry-Perot and Bragg grating sensors - have been embedded very near to the interface of the layers. Measurements were taken on a full scale test sample (slab track panel of 6.45 m length) as well as on a real high speed track. The paper describes the measurement task and discusses aspects with regard to sensor design and prefabrication of the sensor frames as well as the embedding procedure into the concrete track. Results from static and dynamic full scale tests carried out in the testing laboratory of BAM and from measurements on a track are given.

We learn to write by reading, but writing can make you smarter We learn to write by reading, but writing can make you smarter

Directory of Open Access Journals (Sweden)

Stephen Krashen

2008-04-01

Full Text Available My goal in this paper is to make two points: 1. Writing style does not come from writing or from direct instruction, but from reading. 2. Actual writing can help us solve problems and can make us smarter. Writing Style Comes from Reading A substantial amount of research slrongly suggests that wc learn to write by reading. To be more precise, wc acquire writing style, the special language of writing, by reading. Hypothesizing that writing style comes from reading, not from writing or instruction, is consistent with what is known about language acquisition: Most of language acquisition takes place subconsciously, not through deliberate study, and it is a result of input (comprehension, not output (production (Krashen, 1982. Thus, if you wrile a page a day, your writing style or your command of mechanics will not improve. On Ihe other hand, other good things may result from your writing, as we shall see in the second section of this paper. My goal in this paper is to make two points: 1. Writing style does not come from writing or from direct instruction, but from reading. 2. Actual writing can help us solve problems and can make us smarter. Writing Style Comes from Reading A substantial amount of research slrongly suggests that wc learn to write by reading. To be more precise, wc acquire writing style, the special language of writing, by reading. Hypothesizing that writing style comes from reading, not from writing or instruction, is consistent with what is known about language acquisition: Most of language acquisition takes place subconsciously, not through deliberate study, and it is a result of input (comprehension, not output (production (Krashen, 1982. Thus, if you wrile a page a day, your writing style or your command of mechanics will not improve. On Ihe other hand, other good things may result from your writing, as we shall see in the second section of this paper.

Institutional Integrated Teletandem: What have we been learning about writing and peer feedback?

Directory of Open Access Journals (Sweden)

Solange ARANHA

2015-12-01

Full Text Available ABSTRACT We define institutionally integrated teletandem (iiTTD as a series of teletandem sessions that are embedded in regular foreign language lessons, so that such lessons both feed and are fed by teletandem practice. In this paper, we analyze prospective Brazilian teachers correcting American students' writing productions in Portuguese during their participation in an iiTTD. We address issues about how pre-service FL teachers (participants in iiTTD offer writing feedback to their peers. Data included all the texts written and revised during the length of their partnership. Results show that most participants tend to correct their iiTTD partners' written productions in a direct way, focusing mainly on language form and according to their beliefs and experience as learners.

Optical interconnects

CERN Document Server

Chen, Ray T

2006-01-01

This book describes fully embedded board level optical interconnect in detail including the fabrication of the thin-film VCSEL array, its characterization, thermal management, the fabrication of optical interconnection layer, and the integration of devices on a flexible waveguide film. All the optical components are buried within electrical PCB layers in a fully embedded board level optical interconnect. Therefore, we can save foot prints on the top real estate of the PCB and relieve packaging difficulty reduced by separating fabrication processes. To realize fully embedded board level optical

Customization of Protein Single Nanowires for Optical Biosensing.

Science.gov (United States)

Sun, Yun-Lu; Sun, Si-Ming; Wang, Pan; Dong, Wen-Fei; Zhang, Lei; Xu, Bin-Bin; Chen, Qi-Dai; Tong, Li-Min; Sun, Hong-Bo

2015-06-24

An all-protein single-nanowire optical biosensor is constructed by a facile and general femtosecond laser direct writing approach with nanoscale structural customization. As-formed protein single nanowires show excellent optical properties (fine waveguiding performance and bio-applicable transmission windows), and are utilized as evanescent optical nanobiosensors for label-free biotin detection. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

InP quantum dots embedded in GaP: Optical properties and carrier dynamics

International Nuclear Information System (INIS)

Hatami, F.; Masselink, W.T.; Schrottke, L.; Tomm, J.W.; Talalaev, V.; Kristukat, C.; Goni, A.R.

2003-01-01

The optical emission and dynamics of carriers in Stranski-Krastanow self-organized InP quantum dots embedded in a GaP matrix are studied. InP deposited on GaP (001) using gas-source molecular-beam epitaxy forms quantum dots for InP coverage greater than 1.8 monolayers. Strong photoluminescence from the quantum dots is observed up to room temperature at about 2 eV; photoluminescence from the two-dimensional InP wetting layer is measured at about 2.2 eV. Modeling based on the 'model-solid theory' indicates that the band alignment for the InP quantum dots is direct and type I. Furthermore, low-temperature time-resolved photoluminescence measurements indicate that the carrier lifetime in the quantum dots is about 2 ns, typical for type-I quantum dots. Pressure-dependent photoluminescence measurements provide further evidence for a type-I band alignment for InP/GaP quantum dots at normal pressure with the GaP X states lying about 30 meV higher than the Γ states in the InP quantum dots, but indicate that they become type II under hydrostatic pressures of about 1.2 GPa

Training Engineers to Write: Old Assumptions and New Directions.

Science.gov (United States)

Schillaci, William C.

1996-01-01

States that universities and engineering firms do not generally train engineers in business technical writing, although firms benefit from having engineers who can write clear descriptions of their work. Suggests a program to promote writing skills of engineers and engineering students with limited English skills that involves clear, logical lists…

Direct Laser Writing of Single-Material Sheets with Programmable Self-Rolling Capability

Science.gov (United States)

Bauhofer, Anton; KröDel, Sebastian; Bilal, Osama; Daraio, Chiara; Constantinescu, Andrei

Direct laser writing, a sub-class of two-photon polymerization, facilitates 3D-printing of single-material microstructures with inherent residual stresses. Here we show that controlled distribution of these stresses allows for fast and cost-effective fabrication of structures with programmable self-rolling capability. We investigate 2D sheets that evolve into versatile 3D structures. Precise control over the shape morphing potential is acquired through variations in geometry and writing parameters. Effects of capillary action and gravity were shown to be relevant for very thin sheets (thickness 1.5um) are dominated by residual stresses and adhesion forces. The presented structures create local tensions up to 180MPa, causing rolling curvatures of 25E3m-1. A comprehensive analytical model that captures the relevant influence factors was developed based on laminate plate theory. The predicted curvature and directionality correspond well with the experimentally obtained data. Potential applications are found in drug encapsulation and particle traps for emulsions with differing surface energies. This work was supported by the Swiss National Science Foundation.

Electrostatic nanopatterning of PMMA by AFM charge writing for directed nano-assembly

International Nuclear Information System (INIS)

Ressier, L; Nader, V Le

2008-01-01

Electrostatic nanopatterning of poly(methylmethacrylate) (PMMA) thin films by atomic force microscopy (AFM) charge writing was investigated using Kelvin force microscopy (KFM). The lateral size of the electrostatic patterns and the amount of injected charges are closely correlated and can be controlled by the height of the voltage pulses applied to the AFM tip and the tip-sample separation during the writing process. Charge retention measurements show that PMMA has excellent charge storage properties in air under relative humidities from 1% to 60% and withstands immersion in ultra-pure water. This study thus reveals that PMMA is a very promising electret to create efficient electrostatic nanopatterns for directed self-assembly of nanoscale objects, including the broad range of colloidal particles or molecules in aqueous solutions

Enhancing Critical Thinking Skills and Writing Skills through the Variation in Non-Traditional Writing Task

Science.gov (United States)

Sinaga, Parlindungan; Feranie, Shelly

2017-01-01

The research aims to identify the impacts of embedding non-traditional writing tasks within the course of modern physics conducted to the students of Physics Education and Physics Study Programs. It employed a quasi-experimental method with the pretest-posttest control group design. The used instruments were tests on conceptual mastery, tests on…

Large-area nanoimprinting on various substrates by reconfigurable maskless laser direct writing

KAUST Repository

Lee, Daeho

2012-08-10

Laser-assisted, one-step direct nanoimprinting of metal and semiconductor nanoparticles (NPs) was investigated to fabricate submicron structures including mesh, line, nanopillar and nanowire arrays. Master molds were fabricated with high-speed (200mms 1) laser direct writing (LDW) of negative or positive photoresists on Si wafers. The fabrication was completely free of lift-off or reactive ion etching processes. Polydimethylsiloxane (PDMS) stamps fabricated from master molds replicated nanoscale structures (down to 200nm) with no or negligible residual layers on various substrates. The low temperature and pressure used for nanoimprinting enabled direct nanofabrication on flexible substrates. With the aid of high-speed LDW, wafer scale 4inch direct nanoimprinting was demonstrated. © 2012 IOP Publishing Ltd.

A Review of Embedded Systems Education in the Arduino Age: Lessons Learned and Future Directions

Directory of Open Access Journals (Sweden)

Mohammed El-Abd

2017-06-01

Full Text Available In this paper, the subject of embedded systems education in the Arduino age is examined. Arduino is an open-source microcontroller platform that has been widely popular in the past decade among hobbyists and academics. Arduino is increasingly being adopted in courses that span different disciplines in schools and universities. As a result, numerous papers are being published every year in different engineering education conferences and journals reporting the integration of Arduino in teaching. In this work, the impact of Arduino on embedded systems education is investigated. First, challenges facing embedded systems education are identified from the literature. Second, different Arduino teaching integration methodologies reported in the literature are surveyed and analyzed. Third, the question whether Arduino successfully addresses embedded education challenges or not is discussed taking both surveyed findings and recent market trends into consideration. Finally, a number of open-ended research directions are proposed.

Applying Distributed Object Technology to Distributed Embedded Control Systems

DEFF Research Database (Denmark)

Jørgensen, Bo Nørregaard; Dalgaard, Lars

2012-01-01

In this paper, we describe our Java RMI inspired Object Request Broker architecture MicroRMI for use with networked embedded devices. MicroRMI relieves the software developer from the tedious and error-prone job of writing communication protocols for interacting with such embedded devices. MicroR...... in developing control systems for distributed embedded platforms possessing severe resource restrictions.......RMI supports easy integration of high-level application specific control logic with low-level device specific control logic. Our experience from applying MicroRMI in the context of a distributed robotics control application, clearly demonstrates that it is feasible to use distributed object technology...

Optical bio-sensors in microfluidic chips

NARCIS (Netherlands)

Pollnau, Markus; Dongre, C.; Pham Van So, P.V.S.; Bernhardi, Edward; Worhoff, Kerstin; de Ridder, R.M.; Hoekstra, Hugo

2012-01-01

Direct femtosecond laser writing is used to integrate optical waveguides that intersect the microfluidic channels in a commercial optofluidic chip. With laser excitation, fluorescently labeled DNA molecules of different sizes are separated by capillary electrophoresis with high operating speed and

One-step direct-laser metal writing of sub-100 nm 3D silver nanostructures in a gelatin matrix

International Nuclear Information System (INIS)

Kang, SeungYeon; Vora, Kevin; Mazur, Eric

2015-01-01

Developing an ability to fabricate high-resolution, 3D metal nanostructures in a stretchable 3D matrix is a critical step to realizing novel optoelectronic devices such as tunable bulk metal-dielectric optical devices and THz metamaterial devices that are not feasible with alternative techniques. We report a new chemistry method to fabricate high-resolution, 3D silver nanostructures using a femtosecond-laser direct metal writing technique. Previously, only fabrication of 3D polymeric structures or single-/few-layer metal structures was possible. Our method takes advantage of unique gelatin properties to overcome such previous limitations as limited freedom in 3D material design and short sample lifetime. We fabricate more than 15 layers of 3D silver nanostructures with a resolution of less than 100 nm in a stable dielectric matrix that is flexible and has high large transparency that is well-matched for potential applications in the optical and THz metamaterial regimes. This is a single-step process that does not require any further processing. This work will be of interest to those interested in fabrication methods that utilize nonlinear light–matter interactions and the realization of future metamaterials. (fast track communication)

One-step direct-laser metal writing of sub-100 nm 3D silver nanostructures in a gelatin matrix

Science.gov (United States)

Kang, SeungYeon; Vora, Kevin; Mazur, Eric

2015-03-01

Developing an ability to fabricate high-resolution, 3D metal nanostructures in a stretchable 3D matrix is a critical step to realizing novel optoelectronic devices such as tunable bulk metal-dielectric optical devices and THz metamaterial devices that are not feasible with alternative techniques. We report a new chemistry method to fabricate high-resolution, 3D silver nanostructures using a femtosecond-laser direct metal writing technique. Previously, only fabrication of 3D polymeric structures or single-/few-layer metal structures was possible. Our method takes advantage of unique gelatin properties to overcome such previous limitations as limited freedom in 3D material design and short sample lifetime. We fabricate more than 15 layers of 3D silver nanostructures with a resolution of less than 100 nm in a stable dielectric matrix that is flexible and has high large transparency that is well-matched for potential applications in the optical and THz metamaterial regimes. This is a single-step process that does not require any further processing. This work will be of interest to those interested in fabrication methods that utilize nonlinear light-matter interactions and the realization of future metamaterials.

Direct laser writing of nanorough cell microbarriers on anatase/Si and graphite/Si

Energy Technology Data Exchange (ETDEWEB)

Xiang, Y.C. [Departamento de Física Aplicada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid (Spain); Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom); Martínez-Martínez, R.M. [Departamento de Física Aplicada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid (Spain); Torres-Costa, V. [Departamento de Física Aplicada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid (Spain); Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Madrid (Spain); Agulló-Rueda, F. [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), 28049 Madrid (Spain); García-Ruiz, J.P. [Departamento de Biología Molecular, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Manso-Silván, M., E-mail: miguel.manso@uam.es [Departamento de Física Aplicada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid (Spain)

2016-09-01

The formation of hierarchical structures consisting of microstripe barriers decorated with nanorough ablated materials prepared by direct laser writing is described. Linear features of circa 25 μm width and 12 μm height are achieved on amorphous and crystalline titania and graphitic carbon films deposited on silicon. Ablated protrusions build up barriers decorated by nanoscale Si-film reconstructions, as indicated by EDX maps and micro-Raman spectroscopy. Wettability tests show a dramatic change in water contact angle, which leads to almost full wetting after irradiation, irrespective of the original film composition. Fluorescence microscopy images of human mesenchymal stem cells cultured on 1D and 2D structures demonstrate the short term biocompatibility of the ablated surfaces. It is shown that cells adhere, extend and polarize on feature edges, independently of the type of surface, thus suggesting that the created nanoroughness is at the origin of the antifouling behavior. In particular, irradiated anatase and graphite surfaces demonstrate an increased performance of crystalline films for the creation of cell guiding and trapping devices. The results suggest that such laser processing of films may serve as a time-and-cost-efficient method for the design of few-cells analytical surfaces. - Graphical abstract: Response of human mesenchymal stem cells to the microbarriers grown by direct laser writing on anatase/Si. Microbarriers show low colonization and high induction of cellular polarization on the feature edges. Display Omitted - Highlights: • Hierarchical microbarriers by direct IR laser writing on thin films. • Complex reconstruction of irradiated materials includes nanorough features. • Ablated areas become fully wettable. • Short term biocompatibility of the grown hierarchical structures confirmed. • Particular designs functional for cell guiding or trapping.

Direct laser writing of nanorough cell microbarriers on anatase/Si and graphite/Si

International Nuclear Information System (INIS)

Xiang, Y.C.; Martínez-Martínez, R.M.; Torres-Costa, V.; Agulló-Rueda, F.; García-Ruiz, J.P.; Manso-Silván, M.

2016-01-01

The formation of hierarchical structures consisting of microstripe barriers decorated with nanorough ablated materials prepared by direct laser writing is described. Linear features of circa 25 μm width and 12 μm height are achieved on amorphous and crystalline titania and graphitic carbon films deposited on silicon. Ablated protrusions build up barriers decorated by nanoscale Si-film reconstructions, as indicated by EDX maps and micro-Raman spectroscopy. Wettability tests show a dramatic change in water contact angle, which leads to almost full wetting after irradiation, irrespective of the original film composition. Fluorescence microscopy images of human mesenchymal stem cells cultured on 1D and 2D structures demonstrate the short term biocompatibility of the ablated surfaces. It is shown that cells adhere, extend and polarize on feature edges, independently of the type of surface, thus suggesting that the created nanoroughness is at the origin of the antifouling behavior. In particular, irradiated anatase and graphite surfaces demonstrate an increased performance of crystalline films for the creation of cell guiding and trapping devices. The results suggest that such laser processing of films may serve as a time-and-cost-efficient method for the design of few-cells analytical surfaces. - Graphical abstract: Response of human mesenchymal stem cells to the microbarriers grown by direct laser writing on anatase/Si. Microbarriers show low colonization and high induction of cellular polarization on the feature edges. Display Omitted - Highlights: • Hierarchical microbarriers by direct IR laser writing on thin films. • Complex reconstruction of irradiated materials includes nanorough features. • Ablated areas become fully wettable. • Short term biocompatibility of the grown hierarchical structures confirmed. • Particular designs functional for cell guiding or trapping.

Embedded Electro-Optic Sensor Network for the On-Site Calibration and Real-Time Performance Monitoring of Large-Scale Phased Arrays

National Research Council Canada - National Science Library

Yang, Kyoung

2005-01-01

This final report summarizes the progress during the Phase I SBIR project entitled "Embedded Electro-Optic Sensor Network for the On-Site Calibration and Real-Time Performance Monitoring of Large-Scale Phased Arrays...

Light propagation studies on laser modified waveguides using scanning near-field optical microscopy

DEFF Research Database (Denmark)

Borrise, X.; Berini, Abadal Gabriel; Jimenez, D.

2001-01-01

By means of direct laser writing on Al, a new method to locally modify optical waveguides is proposed. This technique has been applied to silicon nitride waveguides, allowing modifications of the optical propagation along the guide. To study the formed structures, a scanning near-held optical mic...

Plasmonic direct writing lithography with a macroscopical contact probe

Science.gov (United States)

Huang, Yuerong; Liu, Ling; Wang, Changtao; Chen, Weidong; Liu, Yunyue; Li, Ling

2018-05-01

In this work, we design a plasmonic direct writing lithography system with a macroscopical contact probe to achieve nanometer scale spots. The probe with bowtie-shaped aperture array adopts spring hinge and beam deflection method (BDM) to realize near-field lithography. Lithography results show that a macroscopical plasmonic contact probe can achieve a patterning resolution of around 75 nm at 365 nm wavelength, and demonstrate that the lithography system is promising for practical applications due to beyond the diffraction limit, low cost, and simplification of system configuration. CST calculations provide a guide for the design of recording structure and the arrangement of placing polarizer.

Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

DEFF Research Database (Denmark)

Pankratov, V.; Osinniy, Viktor; Kotlov, A.

2011-01-01

done. It is demonstrated that the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger than the theoretical predictions. The influence of point defects in the SiO2 matrix on the optical and luminescence properties of the embedded Si nanocrystals...... is discussed. Moreover, it is demonstrated that no energy transfer takes place between the SiO2 and Si nanocrystals when the excitation energy is higher than the band-to-band transition energy in SiO2....

The direct writing and focusing of nanoparticles generated by an electrical discharge

Energy Technology Data Exchange (ETDEWEB)

Saleh, E., E-mail: ems2g09@soton.ac.uk; Praeger, M. [University of Southampton, Optoelectronics Research Centre (United Kingdom); Vaughan, A. S. [University of Southampton, Electronics and Computer Science (United Kingdom); Stewart, W.; Loh, W. H. [University of Southampton, Optoelectronics Research Centre (United Kingdom)

2012-11-15

Direct writing aims to deposit materials onto substrates in localised positions. In this paper, we demonstrate a new method for direct writing of nanoparticles at ambient-air-pressure. An electrical discharge is used to generate gold nanoparticles of the order of 10 nm diameter, which are then transported and 'focused' by an electric field in air, through the process of electric field-assisted diffusion, as opposed to normal ballistic focusing since the mean free path in air is very short. This process is novel and allows for practical normal atmospheric-pressure focused deposition of nanoparticles. The focusing mechanism is capable of producing patterned arrays of deposited nanoparticles with widths that are less than 10 % of the diameter of the focusing apparatus; in the present experimental configuration, gold spots with diameters of a few tens of micrometres were achieved, with ultimate size being limited by transverse diffusion and by charged particle mutual repulsion. In this study, the process of generating nanoparticles from bulk material, transporting and focusing these particles takes place in one operation, which is a key advantage in rapid prototyping and manufacturing techniques.

Mask-free and programmable patterning of graphene by ultrafast laser direct writing

International Nuclear Information System (INIS)

Chen, Hao-Yan; Han, Dongdong; Tian, Ye; Shao, Ruiqiang; Wei, Shu

2014-01-01

Graphical abstract: - Highlights: • We present a mask-free and programmable patterning of graphene. • Ultrafast laser can homogeneously reduce graphene oxides into micropatterns. • Desired graphene micropatterns could be created on flexible substrates. • Laser exposure duration shows influence on the conductivity of reduced graphene. • The method holds promise for fabrication and integration of graphene electronics. - Abstract: Reported here is a mask-free and programmable patterning of graphene by using femtosecond laser direct writing on graphene oxide (GO) films. Take advantage of the ultrahigh instantaneous intensity of the femtosecond laser pulse, and especially its nonlinear interactions with materials, the GO could be efficiently reduced under atmospheric condition at room temperature. Moreover, the designability of femtosecond laser direct writing (FsLDW) technique allow making graphene micropatterns arbitrarily according to the preprogrammed structures, which provides the feasibility for rational design, flexible fabrication and integration of graphene-based micro-devices. Raman spectra show that the reduced and patterned region is very homogeneous, which is confirmed by the almost consistent I D /I G ratio. The novel graphene patterning technique would provide a technical support for the development of graphene-based micro-devices for future electronics

Rejuvenating direct modulation and direct detection for modern optical communications

Science.gov (United States)

Che, Di; Li, An; Chen, Xi; Hu, Qian; Shieh, William

2018-02-01

High-speed transoceanic optical fiber transmission using direct modulation (DM) and direct detection (DD) was one of the most stirring breakthroughs for telecommunication in 1990s, which drove the internet as a global phenomenon. However, the later evolution of optical coherent communications in 2000s gradually took over the long-haul applications, due to its superior optical spectral efficiency. Nowadays, DM-DD systems are dominant mainly in cost- and power-sensitive short-reach applications, because of its natural characteristics-the simplicity. This paper reviews the recent advances of DM-DD transceivers from both hardware and signal processing perspectives. It introduces a variety of modified DM and/or DD systems for 3 application scenarios: very-short-reach interconnect with little fiber channel impact; single or a few spans of fiber transmission up to several hundred km; and distance beyond the 2nd scenario. Besides the DM-DD and multi-dimension DM-DD with polarization diversity, this paper focuses on how to rejuvenate traditional DM and DD technologies in order to bridge the transmission application gap between DM-DD and coherent transceivers, using technologies such as dispersion compensation, signal field recovery from the intensity-only DD receiver, and complex direct modulation with coherent detection. More than 30 years since the birth, DM and DD still hold indispensable roles in modern optical communications.

Recent developments in the use of plastic optical fiber for an embedded wear sensor

Science.gov (United States)

Cohen, Edward I.; Mastro, Stephen A.; Nemarich, Christopher P.; Korczynski, Joseph F., Jr.; Jarrett, Andrew W.; Jones, Wayne C.

1999-05-01

This paper describes recent developments of a practical, low cost embedded plastic optical fiber (POF) wear sensor system for the condition based maintenance of external outboard water lubricated bearings aboard U.S. Navy Ships. The benefit of this measurement system over the status quo is the ability to remotely monitor bearing wear. The Embedded Wear Sensor system (Navy invention disclosure #78,570) features a sacrificial wear fiber embedded into the nitrile rubber bearing. This fiber may also act as a conduit for the transmission of pressure and temperature data that may be resolved into alignment data. The authors selected a commercially-off-the- shelf plastic fiber for the sensor because of its material compatibility with the nitrile rubber bearing staves in terms of flexural modulus and wear properties. Presented herein is a description of the system concept, the results of non-linear finite element analysis, market survey of POF, mold studies, small scale prototyping and abrasive wear testing. A description of the sensor concept and the results of the preliminary finite element analysis of the bearing stave geometry are presented. Preliminary results of molding and glue bonding POF in nitrile rubber and then abrasive wear testing indicate that this is a viable concept.

Feasibility Study on the Development of 2-channel Embedded Infrared Fiber-optic Sensor for Thermometry of Secondary Water System in Nuclear Power Plant

International Nuclear Information System (INIS)

Yoo, W. J.; Jang, K. W.; Seo, J. K.; Moon, J.; Han, K. T.; Lee, B.; Park, B. G.

2011-01-01

Any warm object by measuring the emitted infrared (IR) radiation. The radiometers using infrared optical fibers are based on the relationship between the temperature of a heat source and the quality and the quantity of an IR radiation. To measure physical properties including a temperature, optical fiber-based sensor has many advantages, such as small size, low cost, high resolution, remote sensing and immunity to electromagnetic radiation over conventional electrical sensors. In this study, we carried out the feasibility study on the development of an embedded IR fiber-optic sensor for thermometry of the secondary water system in a nuclear power plant. The 2-channel embedded fiberoptic temperature sensor was fabricated using two identical IR optical fibers for accurate thermometry without complicated calibration processes. To decide accurate temperature of the water, we measured the difference between the IR radiations emitted from the two temperature sensing probes according to the temperature variation of the water

Did you seek assistance for writing your advance directive? A qualitative study.

Science.gov (United States)

Becker, Matthias; Jaspers, Birgit; King, Claudius; Radbruch, Lukas; Voltz, Raymond; Nauck, Friedemann

2010-11-01

the completion of an advanced directive is paired with a high degree of self-responsibility of the signatory. It requires anticipation of probably complex medical situations. In the literature, the family physician is often seen as the most important person for advice when writing an advance directive. But little is known about whether or not patients want to involve medical advisors and to what extent physicians are willing to give advice. The aim of this study was to analyse whether or not individuals approached advisors for the completion of their advance directive, whom they chose and which reasons were given for seeking or foregoing assistance. semi-structured interviews with healthy individuals, chronically ill individuals and patients in palliative care including questions associated with advice for completing an advance directive (8/2008-7/2009). age 55-70 years and advance directive ≥ 3 months old. The interviews were fully transcribed according to standard transcription rules and analysed applying an inductive category development. interviews were conducted with 53 probands (healthy n = 20, chronically ill n = 17, palliative care patients n = 16); 18 probands were male. Mean age was 63.2 ± 4.4 years (range 55-70 years). Professional advice was sought by 12 probands (physician = 2, nurse = 1, lawyer/notary = 8, self-employed advisor = 1), another 8 probands included family members. In 17 cases, the physician knew the proband's advance directive, 36 probands never told their doctor about its existence. Categories of reasons for seeking or foregoing advice were trust/lack of trust, autonomy, rejection and financial considerations. information about the medical implications concerning patient preferences for end-of-life care seems not to be the main focus of interest when individuals write an advance directive. Autonomy and trust into notarially certified documents seem to be more important matters. If family physicians want to have a role in their

Giant nonlinear interaction between two optical beams via a quantum dot embedded in a photonic wire

Science.gov (United States)

Nguyen, H. A.; Grange, T.; Reznychenko, B.; Yeo, I.; de Assis, P.-L.; Tumanov, D.; Fratini, F.; Malik, N. S.; Dupuy, E.; Gregersen, N.; Auffèves, A.; Gérard, J.-M.; Claudon, J.; Poizat, J.-Ph.

2018-05-01

Optical nonlinearities usually appear for large intensities, but discrete transitions allow for giant nonlinearities operating at the single-photon level. This has been demonstrated in the last decade for a single optical mode with cold atomic gases, or single two-level systems coupled to light via a tailored photonic environment. Here, we demonstrate a two-mode giant nonlinearity with a single semiconductor quantum dot (QD) embedded in a photonic wire antenna. We exploit two detuned optical transitions associated with the exciton-biexciton QD level scheme. Owing to the broadband waveguide antenna, the two transitions are efficiently interfaced with two free-space laser beams. The reflection of one laser beam is then controlled by the other beam, with a threshold power as low as 10 photons per exciton lifetime (1.6 nW ). Such a two-color nonlinearity opens appealing perspectives for the realization of ultralow-power logical gates and optical quantum gates, and could also be implemented in an integrated photonic circuit based on planar waveguides.

Facile fabrication of a superhydrophobic cage by laser direct writing for site-specific colloidal self-assembled photonic crystal.

Science.gov (United States)

Yoo, Jae-Hyuck; Kwon, Hyuk-Jun; Paeng, Dongwoo; Yeo, Junyeob; Elhadj, Selim; Grigoropoulos, Costas P

2016-04-08

Micron-sized ablated surface structures with nano-sized 'bumpy' structures were produced by femtosecond (fs) laser ablation of polytetrafluoroethylene (PTFE) film under ambient conditions. Upon just a single step, the processed surface exhibited hierarchical micro/nano morphology. In addition, due to the tribological properties of PTFE, polydimethylsiloxane (PDMS) could be replicated from the laser-ablated PTFE surface without anti-adhesive surface treatment. By controlling the design of the ablated patterns, tunable wettability and superhydrophobicity were achieved on both PTFE and PDMS replica surfaces. Furthermore, using fs laser ablation direct writing, a flexible superhydrophobic PDMS cage formed by superhydrophobic patterns encompassing the unmodified region was demonstrated for aqueous droplet positioning and trapping. Through evaporation-driven colloidal self-assembly in this superhydrophobic cage, a colloidal droplet containing polystyrene (PS) particles dried into a self-assembled photonic crystal, whose optical band gap could be manipulated by the particle size.

Fast‐writing E‐beam for defining large arrays of nano‐holes

DEFF Research Database (Denmark)

Højlund-Nielsen, Emil; Clausen, Jeppe Sandvik; Christiansen, Alexander Bruun

2013-01-01

Efficient nanoscale patterning of large areas is required for sub-wavelength optics. For example, 200 nm periodic structures are often too small to be made with standard UV- and DUV-equipment. Still, the final product must be made at an economic cost. Here we use a fast-writing strategy described...... in [1], where electron beam lithography (EBL) with a focused Gaussian beam is used to define shapes directly. The serial technique is optimized for speed and pattern fidelity to a maximum writing speed of around 30 min/cm2 for 200 nm periods in 2D lattices. The overall costs in terms of machine time...

Optical Fiber Grating based Sensors

DEFF Research Database (Denmark)

Michelsen, Susanne

2003-01-01

In this thesis differenct optical fiber gratings are used for sensor purposes. If a fiber with a core concentricity error (CCE) is used, a directional dependent bend sensor can be produced. The CCE direction can be determined by means of diffraction. This makes it possible to produce long......-period gratings in a fiber with a CCE direction parallel or perpendicular to the writing direction. The maximal bending sensitivity is independent on the writing direction, but the detailed bending response is different in the two cases. A temperature and strain sensor, based on a long-period grating and two...... sampled gratings, was produced and investigated. It is based on the different temperature and strain response of these gratings. Both a transfer matrix method and an overlap calculation is performed to explain the sensor response. Another type of sensor is based on tuning and modulation of a laser...

THEMATIC PROGRESSION PATTERN : A TECHNIQUE TO IMPROVE STUDENTS’ WRITING SKILL VIEWED FROM WRITING APPREHENSION

Directory of Open Access Journals (Sweden)

Fitri Nurdianingsih

2017-10-01

Full Text Available The objective of conducting this research was to find out : (1 whether or not the use of thematic progression pattern is more effective than direct instruction in teaching writing to the second semester students at English Education Department; (2 the students who have a low writing apprehension have better writing skill than those who have a high writng apprehension; and (3 there is an interaction between teaching technique and writing apprehension in teaching writing skill. This reasearch was an experimental research design. The population of this research was the second semester students at English Education Department of IKIP PGRI Bojonegoro. Meanwhile the sample of this research was selected by using cluster random sampling. The instruments of data collection were witing test and writing apprehension questionnaire. The findings of this study are: (1 thematic progression pattern is more effective than direct instruction in teaching writing; (2 the students who have low writing apprehension have better writing skill than those who have high writing apprehension; and (3 there is an interaction between teaching technique and writing apprehension in teaching writing skill. It can be summarized that thematic progression pattern is an effective technique in teaching writing skill at the second semester students of English Education Department in IKIP PGRI Bojonegoro. The effectiveness of the technique is affected by writing apprehension.

Higher-resolution selective metallization on alumina substrate by laser direct writing and electroless plating

Science.gov (United States)

Lv, Ming; Liu, Jianguo; Wang, Suhuan; Ai, Jun; Zeng, Xiaoyan

2016-03-01

How to fabricate conductive patterns on ceramic boards with higher resolution is a challenge in the past years. The fabrication of copper patterns on alumina substrate by laser direct writing and electroless copper plating is a low cost and high efficiency method. Nevertheless, the lower resolution limits its further industrial applications in many fields. In this report, the mechanisms of laser direct writing and electroless copper plating were studied. The results indicated that as the decomposed products of precursor PdCl2 have different chemical states respectively in laser-irradiated zone (LIZ) and laser-affected zone (LAZ). This phenomenon was utilized and a special chemical cleaning method with aqua regia solution was taken to selectively remove the metallic Pd in LAZ, while kept the PdO in LIZ as the only active seeds. As a result, the resolution of subsequent copper patterns was improved significantly. This technique has a great significance to develop the microelectronics devices.

Directional amplifier in an optomechanical system with optical gain

Science.gov (United States)

Jiang, Cheng; Song, L. N.; Li, Yong

2018-05-01

Directional amplifiers are crucial nonreciprocal devices in both classical and quantum information processing. Here we propose a scheme for realizing a directional amplifier between optical and microwave fields based on an optomechanical system with optical gain, where an active optical cavity and two passive microwave cavities are coupled to a common mechanical resonator via radiation pressure. The two passive cavities are coupled via hopping interaction to facilitate the directional amplification between the active and passive cavities. We obtain the condition of achieving optical directional amplification and find that the direction of amplification can be controlled by the phase differences between the effective optomechanical couplings. The effects of the gain rate of the active cavity and the effective coupling strengths on the maximum gain of the amplifier are discussed. We show that the noise added to this amplifier can be greatly suppressed in the large cooperativity limit.

Deep Proton Writing for the rapid prototyping of polymer micro-components for optical interconnects and optofluidics

Science.gov (United States)

Van Erps, Jürgen; Vervaeke, Michael; Ottevaere, Heidi; Hermanne, Alex; Thienpont, Hugo

2013-07-01

The use of photonics in data communication and numerous other industrial applications brought plenty of prospects for innovation and opened up different unexplored market opportunities. This is a major driving force for the fabrication of micro-optical and micro-mechanical structures and their accurate alignment and integration into opto-mechanical modules and systems. To this end, we present Deep Proton Writing (DPW) as a powerful rapid prototyping technology for such micro-components. The DPW process consists of bombarding polymer samples (PMMA or SU-8) with swift protons, which results after chemical processing steps in high-quality micro-optical components. One of the strengths of the DPW micro-fabrication technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we comment on how we shifted from using 8.3 to 16.5 MeV protons for DPW and give some examples of micro-optical and micro-mechanical components recently fabricated through DPW, targeting applications in optical interconnections and in optofluidics.

Deep Proton Writing for the rapid prototyping of polymer micro-components for optical interconnects and optofluidics

Energy Technology Data Exchange (ETDEWEB)

Van Erps, Jürgen, E-mail: jurgen.van.erps@vub.ac.be; Vervaeke, Michael; Ottevaere, Heidi; Hermanne, Alex; Thienpont, Hugo

2013-07-15

The use of photonics in data communication and numerous other industrial applications brought plenty of prospects for innovation and opened up different unexplored market opportunities. This is a major driving force for the fabrication of micro-optical and micro-mechanical structures and their accurate alignment and integration into opto-mechanical modules and systems. To this end, we present Deep Proton Writing (DPW) as a powerful rapid prototyping technology for such micro-components. The DPW process consists of bombarding polymer samples (PMMA or SU-8) with swift protons, which results after chemical processing steps in high-quality micro-optical components. One of the strengths of the DPW micro-fabrication technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. In this paper we comment on how we shifted from using 8.3 to 16.5 MeV protons for DPW and give some examples of micro-optical and micro-mechanical components recently fabricated through DPW, targeting applications in optical interconnections and in optofluidics.

Writing learning cases for an information literacy tutorial

OpenAIRE

Gunhild Austrheim

2010-01-01

The research and writing processes are often hidden mysteries to our students. A key point in the online tutorial Search and Write (Søk and Skriv) has been to supply our students with tools to handle these processes. Learning cases embedded in the tutorial allow us to demonstrate a variety of working techniques and to better cater for a diverse student population. The tutorial can be used as an independent resource for students and as a teaching aid for both library sessions on inform...

On the way to enhance the optical absorption of a-Si in NIR by embedding Mg_2Si thin film

International Nuclear Information System (INIS)

Chernev, I. M.; Shevlyagin, A. V.; Galkin, K. N.; Stuchlik, J.; Remes, Z.; Fajgar, R.; Galkin, N. G.

2016-01-01

Mg_2Si thin film was embedded in amorphous silicon matrix by solid phase epitaxy. The structure and optical properties were investigated by electron energy loss, X-ray photoelectron, Raman, and photo thermal deflection spectroscopy measurements. It was found that in the photon energy range of 0.8–1.7 eV, the light absorption of the structure with magnesium silicide (Mg_2Si) film embedded in a-Si(i) matrix is 1.5 times higher than that for the same structure without Mg_2Si.

Microring embedded hollow polymer fiber laser

Energy Technology Data Exchange (ETDEWEB)

Linslal, C. L., E-mail: linslal@gmail.com; Sebastian, S.; Mathew, S.; Radhakrishnan, P.; Nampoori, V. P. N.; Girijavallabhan, C. P.; Kailasnath, M. [International School of Photonics, Cochin University of Science and Technology, Cochin 22 (India)

2015-03-30

Strongly modulated laser emission has been observed from rhodamine B doped microring resonator embedded in a hollow polymer optical fiber by transverse optical pumping. The microring resonator is fabricated on the inner wall of a hollow polymer fiber. Highly sharp lasing lines, strong mode selection, and a collimated laser beam are observed from the fiber. Nearly single mode lasing with a side mode suppression ratio of up to 11.8 dB is obtained from the strongly modulated lasing spectrum. The microring embedded hollow polymer fiber laser has shown efficient lasing characteristics even at a propagation length of 1.5 m.

Controllable assembly of silver nanoparticles induced by femtosecond laser direct writing

International Nuclear Information System (INIS)

Wang, Huan; Liu, Sen; Zhang, Yong-Lai; Wang, Jian-Nan; Wang, Lei; Xia, Hong; Chen, Qi-Dai; Sun, Hong-Bo; Ding, Hong

2015-01-01

We report controllable assembly of silver nanoparticles (Ag NPs) for patterning of silver microstructures. The assembly is induced by femtosecond laser direct writing (FsLDW). A tightly focused femtosecond laser beam is capable of trapping and driving Ag NPs to form desired micropatterns with a high resolution of ∼190 nm. Taking advantage of the ‘direct writing’ feature, three microelectrodes have been integrated with a microfluidic chip; two silver-based microdevices including a microheater and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices. (focus issue paper)

Characterization of a Reconfigurable Free-Space Optical Channel for Embedded Computer Applications with Experimental Validation Using Rapid Prototyping Technology

Directory of Open Access Journals (Sweden)

Rafael Gil-Otero

2007-02-01

Full Text Available Free-space optical interconnects (FSOIs are widely seen as a potential solution to current and future bandwidth bottlenecks for parallel processors. In this paper, an FSOI system called optical highway (OH is proposed. The OH uses polarizing beam splitter-liquid crystal plate (PBS/LC assemblies to perform reconfigurable beam combination functions. The properties of the OH make it suitable for embedding complex network topologies such as completed connected mesh or hypercube. This paper proposes the use of rapid prototyping technology for implementing an optomechanical system suitable for studying the reconfigurable characteristics of a free-space optical channel. Additionally, it reports how the limited contrast ratio of the optical components can affect the attenuation of the optical signal and the crosstalk caused by misdirected signals. Different techniques are also proposed in order to increase the optical modulation amplitude (OMA of the system.

Characterization of a Reconfigurable Free-Space Optical Channel for Embedded Computer Applications with Experimental Validation Using Rapid Prototyping Technology

Directory of Open Access Journals (Sweden)

Lim Theodore

2007-01-01

Full Text Available Free-space optical interconnects (FSOIs are widely seen as a potential solution to current and future bandwidth bottlenecks for parallel processors. In this paper, an FSOI system called optical highway (OH is proposed. The OH uses polarizing beam splitter-liquid crystal plate (PBS/LC assemblies to perform reconfigurable beam combination functions. The properties of the OH make it suitable for embedding complex network topologies such as completed connected mesh or hypercube. This paper proposes the use of rapid prototyping technology for implementing an optomechanical system suitable for studying the reconfigurable characteristics of a free-space optical channel. Additionally, it reports how the limited contrast ratio of the optical components can affect the attenuation of the optical signal and the crosstalk caused by misdirected signals. Different techniques are also proposed in order to increase the optical modulation amplitude (OMA of the system.

Direct writing on graphene ‘paper’ by manipulating electrons as ‘invisible ink’

International Nuclear Information System (INIS)

Zhang Wei; Theil Kuhn, Luise; Zhang Qiang; Zhao Mengqiang

2013-01-01

The combination of self-assembly (bottom up) and nano-imprint lithography (top down) is an efficient and effective way to record information at the nanoscale by writing. The use of an electron beam for writing is quite a promising strategy; however, the ‘paper’ on which to save the information is not yet fully realized. Herein, graphene was selected as the thinnest paper for recording information at the nanoscale. In a transmission electron microscope, in situ high precision writing and drawing were achieved on graphene nanosheets by manipulating electrons with a 1 nm probe (probe current ∼2 × 10 −9 A m −2 ) in scanning transmission electron microscopy (STEM) mode. Under electron probe irradiation, the carbon atom tends to displace within a crystalline specimen, and dangling bonds are formed from the original sp 2 bonding after local carbon atoms have been kicked off. The absorbed random foreign amorphous carbon assembles along the line of the scanning direction induced by secondary electrons and is immobilized near the edge. With the ultralow secondary electron yield of the graphene, additional foreign atoms determining the accuracy of the pattern have been greatly reduced near the targeting region. Therefore, the electron probe in STEM mode serves as invisible ink for nanoscale writing and drawing. These results not only shed new light on the application of graphene by the interaction of different forms of carbon, but also illuminate the interaction of different carbon forms through electron beams. (paper)

Introduction to Embedded Systems Using ANSI C and the Arduino Development Environment

CERN Document Server

Russell, David

2010-01-01

Many electrical and computer engineering projects involve some kind of embedded system in which a microcontroller sits at the center as the primary source of control. The recently-developed Arduino development platform includes an inexpensive hardware development board hosting an eight-bit ATMEL ATmega-family processor and a Java-based software-development environment. These features allow an embedded systems beginner the ability to focus their attention on learning how to write embedded software instead of wasting time overcoming the engineering CAD tools learning curve. The goal of this text

Manufacturing of the ISO 25178-70 material measures with direct laser writing: a feasibility study

Science.gov (United States)

Eifler, M.; Hering, J.; von Freymann, G.; Seewig, J.

2018-06-01

The standard ISO 25178-70 defines material measures for the calibration of 2D- and 3D-topography measurement devices. Some of the suggested material measures are established within the industrial application for a long time while others have not yet been extensively researched regarding their practical abilities. This paper describes a holistic and systematic investigation of the ISO 25178-70 material measures. The manufacturing of the suggested geometries is executed with two-photon laser lithography, alias direct laser writing (DLW). Since this manufacturing process is not yet frequently used in a material measures context, it is examined regarding its suitability for the fabrication of the ISO 25178-70 material measures. With DLW, it is possible to manufacture multiple material measures on one sample in order to enable a comprehensive calibration of optical topography measurement devices. The manufactured ISO 25178-70 geometries are examined using different 3D-topography measuring devices. In doing so, their abilities regarding the calibration of the devices can be evaluated and the practical feasibility of their industrial application is assessed. For the review of this practical usefulness, varying calibration and evaluation strategies are taken into account.

Integrated Optical Components Utilizing Long-Range Surface Plasmon Polaritons

DEFF Research Database (Denmark)

Boltasseva, Alexandra; Nikolajsen, Thomas; Leosson, Kristjan

2005-01-01

New optical waveguide technology for integrated optics, based on propagation of long-range surface plasmon polaritons (LR-SPPs) along metal stripes embedded in dielectric, is presented. Guiding and routing of electromagnetic radiation along nanometer-thin and micrometer-wide gold stripes embedded......), and a bend loss of ~5 dB for a bend radius of 15 mm are evaluated for 15-nm-thick and 8-mm-wide stripes at the wavelength of 1550 nm. LR-SPP-based 3-dB power Y-splitters, multimode interference waveguides, and directional couplers are demonstrated and investigated. At 1570 nm, coupling lengths of 1.9 and 0...

Molecular Properties through Polarizable Embedding

DEFF Research Database (Denmark)

Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob

2011-01-01

We review the theory related to the calculation of electric and magnetic molecular properties through polarizable embedding. In particular, we derive the expressions for the response functions up to the level of cubic response within the density functional theory-based polarizable embedding (PE......-DFT) formalism. In addition, we discuss some illustrative applications related to the calculation of nuclear magnetic resonance parameters, nonlinear optical properties, and electronic excited states in solution....

Direct-write Bioprinting of Cell-laden Methacrylated Gelatin Hydrogels

Science.gov (United States)

Bertassoni, Luiz E.; Cardoso, Juliana C.; Manoharan, Vijayan; Cristino, Ana L.; Bhise, Nupura S.; Araujo, Wesleyan A.; Zorlutuna, Pinar; Vrana, Nihal E.; Ghaemmaghami, Amir M.

2014-01-01

Fabrication of three dimensional (3D) organoids with controlled microarchitectures has been shown to enhance tissue functionality. Bioprinting can be used to precisely position cells and cell-laden materials to generate controlled tissue architecture. Therefore, it represents an exciting alternative for organ fabrication. Despite the rapid progress in the field, the development of printing processes that can be used to fabricate macroscale tissue constructs from ECM-derived hydrogels has remained a challenge. Here we report a strategy for bioprinting of photolabile cell-laden methacrylated gelatin (GelMA) hydrogels. We bioprinted cell-laden GelMA at concentrations ranging from 7 to 15% with varying cell densities and found a direct correlation between printability and the hydrogel mechanical properties. Furthermore, encapsulated HepG2 cells preserved cell viability for at least 8 days following the bioprinting process. In summary, this work presents a strategy for direct-write bioprinting of a cell-laden photolabile ECM-derived hydrogel, which may find widespread application for tissue engineering, organ printing and the development of 3D drug discovery platforms. PMID:24695367

Direct-write bioprinting of cell-laden methacrylated gelatin hydrogels

International Nuclear Information System (INIS)

Bertassoni, Luiz E; Cardoso, Juliana C; Manoharan, Vijayan; Cristino, Ana L; Bhise, Nupura S; Araujo, Wesleyan A; Zorlutuna, Pinar; Vrana, Nihal E; Dokmeci, Mehmet R; Khademhosseini, Ali; Ghaemmaghami, Amir M

2014-01-01

Fabrication of three dimensional (3D) organoids with controlled microarchitectures has been shown to enhance tissue functionality. Bioprinting can be used to precisely position cells and cell-laden materials to generate controlled tissue architecture. Therefore, it represents an exciting alternative for organ fabrication. Despite the rapid progress in the field, the development of printing processes that can be used to fabricate macroscale tissue constructs from ECM-derived hydrogels has remained a challenge. Here we report a strategy for bioprinting of photolabile cell-laden methacrylated gelatin (GelMA) hydrogels. We bioprinted cell-laden GelMA at concentrations ranging from 7 to 15% with varying cell densities and found a direct correlation between printability and the hydrogel mechanical properties. Furthermore, encapsulated HepG2 cells preserved cell viability for at least eight days following the bioprinting process. In summary, this work presents a strategy for direct-write bioprinting of a cell-laden photolabile ECM-derived hydrogel, which may find widespread application for tissue engineering, organ printing and the development of 3D drug discovery platforms. (paper)

Direct-write bioprinting of cell-laden methacrylated gelatin hydrogels.

Science.gov (United States)

Bertassoni, Luiz E; Cardoso, Juliana C; Manoharan, Vijayan; Cristino, Ana L; Bhise, Nupura S; Araujo, Wesleyan A; Zorlutuna, Pinar; Vrana, Nihal E; Ghaemmaghami, Amir M; Dokmeci, Mehmet R; Khademhosseini, Ali

2014-06-01

Fabrication of three dimensional (3D) organoids with controlled microarchitectures has been shown to enhance tissue functionality. Bioprinting can be used to precisely position cells and cell-laden materials to generate controlled tissue architecture. Therefore, it represents an exciting alternative for organ fabrication. Despite the rapid progress in the field, the development of printing processes that can be used to fabricate macroscale tissue constructs from ECM-derived hydrogels has remained a challenge. Here we report a strategy for bioprinting of photolabile cell-laden methacrylated gelatin (GelMA) hydrogels. We bioprinted cell-laden GelMA at concentrations ranging from 7 to 15% with varying cell densities and found a direct correlation between printability and the hydrogel mechanical properties. Furthermore, encapsulated HepG2 cells preserved cell viability for at least eight days following the bioprinting process. In summary, this work presents a strategy for direct-write bioprinting of a cell-laden photolabile ECM-derived hydrogel, which may find widespread application for tissue engineering, organ printing and the development of 3D drug discovery platforms.

Announcing the ESL-WOW for Self-Directed Writing Support

Directory of Open Access Journals (Sweden)

Thaddeus M. Niles

2013-03-01

Full Text Available This is an overview of ESL-WOW (Writing Online Workshop, a new online resource for students aiming to develop academic writing skills which has been available to the public at no charge since December 2012. Students can visit www.esl-wow.org to learn more about the academic conventions that confound new entrants into academic discourse communities, or to learn more about what makes writing clear and cogent in general. While the site is designed for adult learners and students entering community colleges, a wide variety of intermediate and advanced learners can certainly benefit from the materials offered by the ESL-WOW.

Elasto-plastic bond mechanics of embedded fiber optic sensors in concrete under uniaxial tension with strain localization

Science.gov (United States)

Li, Qingbin; Li, Guang; Wang, Guanglun

2003-12-01

Brittleness of the glass core inside fiber optic sensors limits their practical usage, and therefore they are coated with low-modulus softer protective materials. Protective coatings absorb a portion of the strain, and hence part of the structural strain is sensed. The study reported here corrects for this error through development of a theoretical model to account for the loss of strain in the protective coating of optical fibers. The model considers the coating as an elasto-plastic material and formulates strain transfer coefficients for elastic, elasto-plastic and strain localization phases of coating deformations in strain localization in concrete. The theoretical findings were verified through laboratory experimentation. The experimental program involved fabrication of interferometric optical fiber sensors, embedding within mortar samples and tensile tests in a closed-loop servo-hydraulic testing machine. The elasto-plastic strain transfer coefficients were employed for correction of optical fiber sensor data and results were compared with those of conventional extensometers.

Microfabricated ommatidia using a laser induced self-writing process for high resolution artificial compound eye optical systems.

Science.gov (United States)

Jung, Hyukjin; Jeong, Ki-Hun

2009-08-17

A microfabricated compound eye, comparable to a natural compound eye shows a spherical arrangement of integrated optical units called artificial ommatidia. Each consists of a self-aligned microlens and waveguide. The increase of waveguide length is imperative to obtain high resolution images through an artificial compound eye for wide field-of - view imaging as well as fast motion detection. This work presents an effective method for increasing the waveguide length of artificial ommatidium using a laser induced self-writing process in a photosensitive polymer resin. The numerical and experimental results show the uniform formation of waveguides and the increment of waveguide length over 850 microm. (c) 2009 Optical Society of America

A embedded Linux system based on PowerPC

International Nuclear Information System (INIS)

Ye Mei; Zhao Jingwei; Chu Yuanping

2006-01-01

The authors will introduce a Embedded Linux System based on PowerPC as well as the base method on how to establish the system. The goal of the system is to build a test system of VMEbus device. It also can be used to setup the small data acquisition and control system. Two types of compiler are provided by the developer system according to the features of the system and the Power PC. At the top of the article some typical embedded Operation system will be introduced and the features of different system will be provided. And then the method on how to build a embedded Linux system as well as the key technique will be discussed in detail. Finally a successful read-write example will be given based on the test system. (authors)

Identification of constitutive theory parameters using a tensile machine for deposited filaments of microcrystalline ink by the direct-write method

International Nuclear Information System (INIS)

Lourdel, N; Therriault, D; Lévesque, M

2009-01-01

A custom-designed tensile machine is developed to characterize the mechanical properties of ink micro-filaments deposited by the direct-write method. The direct-write method has been used for the fabrication of a wide variety of micro-systems such as microvascular networks, chaotic mixers and laboratory on chips. The tensile machine was used to measure the induced force in ink filaments during tensile and tension-relaxation tests as a function of the applied strain rate, the ink composition and the filament diameter. Experimental data were fitted by a linearly viscoelastic model using a data reduction procedure in order to identify the constitutive theory parameters of the deposited ink filaments. The model predictions based on the linearly viscoelastic model and the defined constitutive theory parameters give a close approximation of all experimental data generated in this study. Such models will be useful for the development and optimization of future 3D complex structures made by the direct-write method

Stable dissipative optical vortex clusters by inhomogeneous effective diffusion.

Science.gov (United States)

Li, Huishan; Lai, Shiquan; Qui, Yunli; Zhu, Xing; Xie, Jianing; Mihalache, Dumitru; He, Yingji

2017-10-30

We numerically show the generation of robust vortex clusters embedded in a two-dimensional beam propagating in a dissipative medium described by the generic cubic-quintic complex Ginzburg-Landau equation with an inhomogeneous effective diffusion term, which is asymmetrical in the two transverse directions and periodically modulated in the longitudinal direction. We show the generation of stable optical vortex clusters for different values of the winding number (topological charge) of the input optical beam. We have found that the number of individual vortex solitons that form the robust vortex cluster is equal to the winding number of the input beam. We have obtained the relationships between the amplitudes and oscillation periods of the inhomogeneous effective diffusion and the cubic gain and diffusion (viscosity) parameters, which depict the regions of existence and stability of vortex clusters. The obtained results offer a method to form robust vortex clusters embedded in two-dimensional optical beams, and we envisage potential applications in the area of structured light.

Orchestrated structure evolution: accelerating direct-write nanomanufacturing by combining top-down patterning with bottom-up growth

Energy Technology Data Exchange (ETDEWEB)

Kitayaporn, Sathana; Baneyx, Francois; Schwartz, Daniel T [Department of Chemical Engineering, University of Washington, Seattle, WA 98195-1750 (United States); Hoo, Ji Hao; Boehringer, Karl F, E-mail: dts@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, WA 98195-1750 (United States)

2010-05-14

Direct-write nanomanufacturing with scanning beams and probes is flexible and can produce high quality products, but it is normally slow and expensive to raster point-by-point over a pattern. We demonstrate the use of an accelerated direct-write nanomanufacturing method called 'orchestrated structure evolution' (OSE), where a direct-write tool patterns a small number of growth 'seeds' that subsequently grow into the final thin film pattern. Through control of seed size and spacing, it is possible to vary the ratio of 'top-down' to 'bottom-up' character of the patterning processes, ranging from conventional top-down raster patterning to nearly pure bottom-up space-filling via seed growth. Electron beam lithography (EBL) and copper electrodeposition were used to demonstrate trade-offs between process time and product quality over nano- to microlength scales. OSE can reduce process times for high-cost EBL patterning by orders of magnitude, at the expense of longer (but inexpensive) copper electrodeposition processing times. We quantify the degradation of pattern quality that accompanies fast OSE patterning by measuring deviations from the desired patterned area and perimeter. We also show that the density of OSE-induced grain boundaries depends upon the seed separation and size. As the seed size is reduced, the uniformity of an OSE film becomes more dependent on details of seed nucleation processes than normally seen for conventionally patterned films.

Patterned direct-write and screen-printing of NIR-to-visible upconverting inks for security applications.

Science.gov (United States)

Blumenthal, Tyler; Meruga, Jeevan; Stanley May, P; Kellar, Jon; Cross, William; Ankireddy, Krishnamraju; Vunnam, Swathi; Luu, Quocanh N

2012-05-11

Two methods of direct-write printing for producing highly resolved features of a polymer impregnated with luminescent upconversion phosphors for security applications are presented. The printed polymer structures range in shape from features to text. The thin polymer features were deposited by direct-write printing of atomized material as well as by screen-printing techniques. These films contain highly luminescent lanthanide-doped, rare-earth nanocrystals, β-NaYF₄:3%Er, 17%Yb, which are capped with oleic acid. This capping agent allows the nanocrystals to disperse throughout the films for full detailing of printed features. Upconversion of deposited features was obtained using a 980 nm wavelength laser with emission of upconverted light in the visible region at both 540 and 660 nm. Features were deposited onto high bond paper, Kapton®, and glass to demonstrate possible covert and forensic security printing applications, as they are printed in various features and invisible to 'naked-eye' viewing at low concentrations of nanocrystals.

Patterned direct-write and screen-printing of NIR-to-visible upconverting inks for security applications

International Nuclear Information System (INIS)

Blumenthal, Tyler; Meruga, Jeevan; Kellar, Jon; Cross, William; Ankireddy, Krishnamraju; Vunnam, Swathi; Stanley May, P; Luu, QuocAnh N

2012-01-01

Two methods of direct-write printing for producing highly resolved features of a polymer impregnated with luminescent upconversion phosphors for security applications are presented. The printed polymer structures range in shape from features to text. The thin polymer features were deposited by direct-write printing of atomized material as well as by screen-printing techniques. These films contain highly luminescent lanthanide-doped, rare-earth nanocrystals, β-NaYF 4 :3%Er, 17%Yb, which are capped with oleic acid. This capping agent allows the nanocrystals to disperse throughout the films for full detailing of printed features. Upconversion of deposited features was obtained using a 980 nm wavelength laser with emission of upconverted light in the visible region at both 540 and 660 nm. Features were deposited onto high bond paper, Kapton ® , and glass to demonstrate possible covert and forensic security printing applications, as they are printed in various features and invisible to ‘naked-eye’ viewing at low concentrations of nanocrystals. (paper)

Patterned direct-write and screen-printing of NIR-to-visible upconverting inks for security applications

Science.gov (United States)

Blumenthal, Tyler; Meruga, Jeevan; May, P. Stanley; Kellar, Jon; Cross, William; Ankireddy, Krishnamraju; Vunnam, Swathi; Luu, QuocAnh N.

2012-05-01

Two methods of direct-write printing for producing highly resolved features of a polymer impregnated with luminescent upconversion phosphors for security applications are presented. The printed polymer structures range in shape from features to text. The thin polymer features were deposited by direct-write printing of atomized material as well as by screen-printing techniques. These films contain highly luminescent lanthanide-doped, rare-earth nanocrystals, β-NaYF4:3%Er, 17%Yb, which are capped with oleic acid. This capping agent allows the nanocrystals to disperse throughout the films for full detailing of printed features. Upconversion of deposited features was obtained using a 980 nm wavelength laser with emission of upconverted light in the visible region at both 540 and 660 nm. Features were deposited onto high bond paper, Kapton®, and glass to demonstrate possible covert and forensic security printing applications, as they are printed in various features and invisible to ‘naked-eye’ viewing at low concentrations of nanocrystals.

The role of research-article writing motivation and self-regulatory strategies in explaining research-article abstract writing ability.

Science.gov (United States)

Lin, Ming-Chia; Cheng, Yuh-Show; Lin, Sieh-Hwa; Hsieh, Pei-Jung

2015-04-01

The purpose of the study was to investigate the effects of research-article writing motivation and use of self-regulatory writing strategies in explaining second language (L2) research-article abstract writing ability, alongside the L2 literacy effect. Four measures were administered: a L2 literacy test, a research abstract performance assessment, and inventories of writing motivation and strategy. Participants were L2 graduate students in Taiwan (N=185; M age=25.8 yr., SD=4.5, range=22-53). Results of structural equation modeling showed a direct effect of motivation on research-article writing ability, but no direct effect of strategy or indirect effect of motivation via strategy on research-article writing ability, with L2 literacy controlled. The findings suggest research-article writing instruction should address writing motivation, besides L2 literacy.

Embedded Fiber Optic Sensors for Integral Armor

National Research Council Canada - National Science Library

Fink, Bruce

2000-01-01

This report describes the work performed with Production Products Manufacturing & Sales (PPMS), Inc., under the "Liquid Molded Composite Armor Smart Structures Using Embedded Sensors" Small Business Innovative Research...

On the way to enhance the optical absorption of a-Si in NIR by embedding Mg{sub 2}Si thin film

Energy Technology Data Exchange (ETDEWEB)

Chernev, I. M., E-mail: igor-chernev7@mail.ru; Shevlyagin, A. V.; Galkin, K. N. [Institute of Automation and Control Processes of FEB RAS, Radio St. 5, 690041 Vladivostok (Russian Federation); Stuchlik, J. [Institute of Physics of the ASCR, v. v. i., Cukrovarnická 10/112, 162 00 Praha 6 (Czech Republic); Remes, Z. [Institute of Physics of the ASCR, v. v. i., Cukrovarnická 10/112, 162 00 Praha 6 (Czech Republic); FBE CTU, Nam. Sitna 3105, 272 01 Kladno (Czech Republic); Fajgar, R. [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojová 135, 165 02 Praha 6 (Czech Republic); Galkin, N. G. [Institute of Automation and Control Processes of FEB RAS, Radio St. 5, 690041 Vladivostok (Russian Federation); Far Eastern Federal University, School of Natural Sciences, Sukhanova St. 8, 690950 Vladivostok (Russian Federation)

2016-07-25

Mg{sub 2}Si thin film was embedded in amorphous silicon matrix by solid phase epitaxy. The structure and optical properties were investigated by electron energy loss, X-ray photoelectron, Raman, and photo thermal deflection spectroscopy measurements. It was found that in the photon energy range of 0.8–1.7 eV, the light absorption of the structure with magnesium silicide (Mg{sub 2}Si) film embedded in a-Si(i) matrix is 1.5 times higher than that for the same structure without Mg{sub 2}Si.

Si Micro-turbine by Proton BeamWriting and Porous Silicon Micromachining

International Nuclear Information System (INIS)

Rajta, I.; Szilasi, S.Z.; Fekete, Z.

2008-01-01

Complete text of publication follows. A 3D Si micro-turbine characterized by high aspect ratio vertical walls was formed by the combination of proton beam writing (PBW) and subsequent selective porous Si (PS) etching. Crystal damages generated by the implanted protons result in increased resistivity, thereby limit or even prevent the current to flow through the implanted area during electrochemical etching. Characteristic feature of the proposed process is that the shape of the micro electromechanical (MEMS) components is defined by two implantation energies. A higher energy is applied for defining the housing of the device while the lower energy is used to write the moving components. The implantation energies were selected such as to result appropriate difference between the two projected ranges, thereby providing structures with different height after development. The thickness of the walls of the moving component and the isotropic etching profile of the electrochemical PS formation was also taken into consideration. The electrochemical etching is driven until the sacrificial PS layer completely under etches the moving components, but the etch-front does not reach the bottom of the housing. Therefore, the dissolution of PS results in a ready-to-operate device with a released moving component embedded in the cavity of the housing. The operation of the encapsulated device fabricated by the two-energy implantation is successfully demonstrated (Fig. 1). Rotation speed of the device is estimated in the range of thousands rpm, however, further analysis of the novel structure optimized for performance and MEMS compatible assembly will be done and precise characteristics will be determined by adequate optical read-out method. The feasibility of Proton Beam Writing combined with Porous Si Micromachining and conventional Si processing steps was successfully demonstrated by fabricating Si microturbine chip. The aligned, two-energy proton beam implantation can provide high

Fabrication of Si-nozzles for parallel mechano-electrospinning direct writing

International Nuclear Information System (INIS)

Pan, Yanqiao; Huang, YongAn; Bu, Ningbin; Yin, Zhouping

2013-01-01

Nozzles with micro-scale orifices drive high-resolution printing techniques for generating micro- to nano-scale droplets/lines. This paper presents the fabrication and application of Si-nozzles in mechano-electrospinning (MES). The fabrication process mainly consists of photolithography, Au deposition, inductively coupled plasma, and polydimethylsiloxane encapsulation. The 6 wt% polyethylene oxide solution is adopted to study the electrospinning behaviour and the relations between fibre diameter and process parameters in MES. A fibre grid with 250 µm spacing is able to be direct written, and the diameters are less than 3 µm. To improve the printing efficiency, positioning accuracy and flexibility, a rotatable multi-nozzle is adopted. The distance between parallel lines reduces sharply from 4.927 to 0.308 mm with the rotating angle increasing from 0° to 87°, and the fibre grids with tunable distance are achieved. This method paves the way for fabrication of addressable Si-nozzle array in parallel MES direct writing. (paper)

Embedding objects during 3D printing to add new functionalities.

Science.gov (United States)

Yuen, Po Ki

2016-07-01

A novel method for integrating and embedding objects to add new functionalities during 3D printing based on fused deposition modeling (FDM) (also known as fused filament fabrication or molten polymer deposition) is presented. Unlike typical 3D printing, FDM-based 3D printing could allow objects to be integrated and embedded during 3D printing and the FDM-based 3D printed devices do not typically require any post-processing and finishing. Thus, various fluidic devices with integrated glass cover slips or polystyrene films with and without an embedded porous membrane, and optical devices with embedded Corning(®) Fibrance™ Light-Diffusing Fiber were 3D printed to demonstrate the versatility of the FDM-based 3D printing and embedding method. Fluid perfusion flow experiments with a blue colored food dye solution were used to visually confirm fluid flow and/or fluid perfusion through the embedded porous membrane in the 3D printed fluidic devices. Similar to typical 3D printed devices, FDM-based 3D printed devices are translucent at best unless post-polishing is performed and optical transparency is highly desirable in any fluidic devices; integrated glass cover slips or polystyrene films would provide a perfect optical transparent window for observation and visualization. In addition, they also provide a compatible flat smooth surface for biological or biomolecular applications. The 3D printed fluidic devices with an embedded porous membrane are applicable to biological or chemical applications such as continuous perfusion cell culture or biocatalytic synthesis but without the need for any post-device assembly and finishing. The 3D printed devices with embedded Corning(®) Fibrance™ Light-Diffusing Fiber would have applications in display, illumination, or optical applications. Furthermore, the FDM-based 3D printing and embedding method could also be utilized to print casting molds with an integrated glass bottom for polydimethylsiloxane (PDMS) device replication

Direct generation of all-optical random numbers from optical pulse amplitude chaos.

Science.gov (United States)

Li, Pu; Wang, Yun-Cai; Wang, An-Bang; Yang, Ling-Zhen; Zhang, Ming-Jiang; Zhang, Jian-Zhong

2012-02-13

We propose and theoretically demonstrate an all-optical method for directly generating all-optical random numbers from pulse amplitude chaos produced by a mode-locked fiber ring laser. Under an appropriate pump intensity, the mode-locked laser can experience a quasi-periodic route to chaos. Such a chaos consists of a stream of pulses with a fixed repetition frequency but random intensities. In this method, we do not require sampling procedure and external triggered clocks but directly quantize the chaotic pulses stream into random number sequence via an all-optical flip-flop. Moreover, our simulation results show that the pulse amplitude chaos has no periodicity and possesses a highly symmetric distribution of amplitude. Thus, in theory, the obtained random number sequence without post-processing has a high-quality randomness verified by industry-standard statistical tests.

Damage detection in laminar thermoplastic composite materials by means of embedded optical fibers

Directory of Open Access Journals (Sweden)

Kojović Aleksandar M.

2006-01-01

Full Text Available This paper investigates the possibility of applying optical fibers as sensors for investigating low energy impact damage in laminar thermoplastic composite materials, in real time. Impact toughness testing by a Charpy impact pendulum with different loads was conducted in order to determine the method for comparative measurement of the resulting damage in the material. For that purpose intensity-based optical fibers were built in to specimens of composite materials with Kevlar 129 (the DuPont registered trade-mark for poly(p-phenylene terephthalamide woven fabric as reinforcement and thermoplastic PVB (poly(vinyl butyral as the matrix. In some specimens part of the layers of Kevlar was replaced with metal mesh (50% or 33% of the layers. Experimental testing was conducted in order to observe and analyze the response of the material under multiple low-energy impacts. Light from the light-emitting diode (LED was launched to the embedded optical fiber and was propagated to the phototransistor-based photo detector. During each impact, the signal level, which is proportional to the light intensity in the optical fiber, drops and then slowly recovers. The obtained signals were analyzed to determine the appropriate method for real time damage monitoring. The major part of the damage occurs during impact. The damage reflects as a local, temporary release of strain in the optical fiber and an increase of the signal level. The obtained results show that intensity-based optical fibers could be used for measuring the damage in laminar thermoplastic composite materials. The acquired optical fiber signals depend on the type of material, but the same set of rules (relatively different, depending on the type of material could be specified. Using real time measurement of the signal during impact and appropriate analysis enables quantitative evaluation of the impact damage in the material. Existing methods in most cases use just the intensity of the signal before

Laser writing of coherent colour centres in diamond

Science.gov (United States)

Chen, Yu-Chen; Salter, Patrick S.; Knauer, Sebastian; Weng, Laiyi; Frangeskou, Angelo C.; Stephen, Colin J.; Ishmael, Shazeaa N.; Dolan, Philip R.; Johnson, Sam; Green, Ben L.; Morley, Gavin W.; Newton, Mark E.; Rarity, John G.; Booth, Martin J.; Smith, Jason M.

2017-02-01

Optically active point defects in crystals have gained widespread attention as photonic systems that could be applied in quantum information technologies. However, challenges remain in the placing of individual defects at desired locations, an essential element of device fabrication. Here we report the controlled generation of single negatively charged nitrogen-vacancy (NV-) centres in diamond using laser writing. Aberration correction in the writing optics allows precise positioning of the vacancies within the diamond crystal, and subsequent annealing produces single NV- centres with a probability of success of up to 45 ± 15%, located within about 200 nm of the desired position in the transverse plane. Selected NV- centres display stable, coherent optical transitions at cryogenic temperatures, a prerequisite for the creation of distributed quantum networks of solid-state qubits. The results illustrate the potential of laser writing as a new tool for defect engineering in quantum technologies, and extend laser processing to the single-defect domain.

Microstructures and Recording Mechanism of Mo/Si Bilayer Applied for Write-Once Blue Laser Optical Recording

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Sin-Liang Ou

2014-01-01

Full Text Available Mo/Si bilayer thin films were grown by magnetron sputtering and applied to write-once blu-ray disc (BD-R. The microstructures and optical storage properties of Mo/Si bilayer were investigated. From the temperature dependence of reflectivity measurement, it was revealed that a phase change occurred in the range of 255–425°C. Transmission electron microscopy analysis showed that the as-deposited film possessed Mo polycrystalline phase. The hexagonal MoSi2 and cubic Mo3Si phases appeared after annealing at 300 and 450°C, respectively. By measuring the optical reflectivity at a wavelength of 405 nm, the optical contrast of Mo/Si bilayer between as-deposited and 450°C-annealed states was evaluated to 25.8%. The optimum jitter value of 6.8% was obtained at 10.65 mW for 4× recording speed. The dynamic tests show that the Mo/Si bilayer has high potential in BD-R applications.

Linear and nonlinear intraband optical properties of ZnO quantum dots embedded in SiO2 matrix

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Deepti Maikhuri

2012-03-01

Full Text Available In this work we investigate some optical properties of semiconductor ZnO spherical quantum dot embedded in an amorphous SiO2 dielectric matrix. Using the framework of effective mass approximation, we have studied intraband S-P, and P-D transitions in a singly charged spherical ZnO quantum dot. The optical properties are investigated in terms of the linear and nonlinear photoabsorption coefficient, the change in refractive index, and the third order nonlinear susceptibility and oscillator strengths. Using the parabolic confinement potential of electron in the dot these parameters are studied with the variation of the dot size, and the energy and intensity of incident radiation. The photoionization cross sections are also obtained for the different dot radii from the initial ground state of the dot. It is found that dot size, confinement potential, and incident radiation intensity affects intraband optical properties of the dot significantly.

Revision Strategies for Adolescent Writers: Moving Students in the Write Direction

Science.gov (United States)

Borgese, Jolene; Heyler, Dick; Romano, Stephanie

2011-01-01

For many secondary students, writing effectively is the most elusive of the critical literacy skills needed for college and career readiness. And for many teachers, revision is the most difficult part of the writing process to tackle. How can adolescent writers be guided to revisit their work, to identify the weaknesses in their writing drafts,…

Diode-laser pumping into the emitting level for efficient lasing of depressed cladding waveguides realized in Nd:YVO4 by the direct femtosecond-laser writing technique.

Science.gov (United States)

Pavel, Nicolaie; Salamu, Gabriela; Jipa, Florin; Zamfirescu, Marian

2014-09-22

Depressed cladding waveguides have been realized in Nd:YVO(4) employing direct writing technique with a femtosecond-laser beam. It was shown that the output performances of such laser devices are improved by the reduction of the quantum defect between the pump wavelength and the laser wavelength. Thus, under the classical pump at 808 nm (i.e. into the (4)F(5/2) level), a 100-μm diameter circular waveguide inscribed in a 0.7-at.% Nd:YVO(4) outputted 1.06-μm laser pulses with 3.0-mJ energy, at 0.30 optical efficiency and slope efficiency of 0.32. The pump at 880 nm (i.e.directly into the (4)F(3/2) emitting level) increased the pulse energy at 3.8 mJ and improved both optical efficiency and slope efficiency at 0.36 and 0.39, respectively. The same waveguide yielded continuous-wave 1.5-W output power at 1.06 μm under the pump at 880 nm. Laser emission at 1.34 μm was also improved using the pump into the (4)F(3/2) emitting level of Nd:YVO(4).

New Directions in Postcolonial Studies: a review of Absolutely Postcolonial: Writing Between the Singular and the Specific 5 New Directions in Postcolonial Studies: a review of Absolutely Postcolonial: Writing Between the Singular and the Specific 5

Directory of Open Access Journals (Sweden)

Jessica Schagerl

2008-04-01

Full Text Available Peter Hallward’s aggressively theoretical book, Absolutely Postcolonial: Writing Between the Singular and the Specific, offers a focused reconceptualisation of some of the critical terms in contemporary postcolonial discourse. Accordingly, Hallward’s book marks a new direction for postcolonial literary studies since in contrast to much postcolonial theory, which has often privileged poststructuralist notions of hybridity, heterogeneity, and contingency, Hallward argues that the postcolonial is singular, subjective, and non-relational and can be best understood in tension with the specific. Peter Hallward’s aggressively theoretical book, Absolutely Postcolonial: Writing Between the Singular and the Specific, offers a focused reconceptualisation of some of the critical terms in contemporary postcolonial discourse. Accordingly, Hallward’s book marks a new direction for postcolonial literary studies since in contrast to much postcolonial theory, which has often privileged poststructuralist notions of hybridity, heterogeneity, and contingency, Hallward argues that the postcolonial is singular, subjective, and non-relational and can be best understood in tension with the specific.

Directly writing resistor, inductor and capacitor to composite functional circuits: a super-simple way for alternative electronics.

Science.gov (United States)

Gao, Yunxia; Li, Haiyan; Liu, Jing

2013-01-01

The current strategies for making electronic devices are generally time, water, material and energy consuming. Here, the direct writing of composite functional circuits through comprehensive use of GaIn10-based liquid metal inks and matching material is proposed and investigated, which is a rather easy going and cost effective electronics fabrication way compared with the conventional approaches. Owing to its excellent adhesion and electrical properties, the liquid metal ink was demonstrated as a generalist in directly making various basic electronic components such as planar resistor, inductor and capacitor or their combination and thus composing circuits with expected electrical functions. For a precise control of the geometric sizes of the writing, a mask with a designed pattern was employed and demonstrated. Mechanisms for justifying the chemical components of the inks and the magnitudes of the target electronic elements so as to compose various practical circuits were disclosed. Fundamental tests on the electrical components including capacitor and inductor directly written on paper with working time up to 48 h and elevated temperature demonstrated their good stability and potential widespread adaptability especially when used in some high frequency circuits. As the first proof-of-concept experiment, a typical functional oscillating circuit including an integrated chip of 74HC04 with a supply voltage of 5 V, a capacitor of 10 nF and two resistors of 5 kΩ and 1 kΩ respectively was directly composed on paper through integrating specific electrical elements together, which presented an oscillation frequency of 8.8 kHz. The present method significantly extends the roles of the metal ink in recent works serving as only a single electrical conductor or interconnecting wires. It opens the way for directly writing out complex functional circuits or devices on different substrates. Such circuit composition strategy has generalized purpose and can be extended to more

Effects of Embedded and Direct Language Strategies on Prekindergarten Students' Cognitive and Social Emotional Development

Science.gov (United States)

Dominy, Matthew L.

2012-01-01

The purpose of this study is to measure the effect of a standard of care embedded language strategies program utilized in combination with direct language strategy instruction on the measured expressive language, cognitive development, social emotional development, and language development of prekindergarten students attending three neighborhood…

Writing Like a Scientist: Exploring Elementary Teachers' Understandings and Practices of Writing in Science

Science.gov (United States)

Glen, Nicole J.; Dotger, Sharon

2013-10-01

This qualitative study examined the connections between elementary teachers’ conceptions of how scientists use writing and how the teachers used writing during science lessons. Data collected included lesson observations, interviews, handouts to students, and curriculum resources. The findings revealed that teachers in this study thought scientists write for several purposes: the presentation of data, observations, experiences, procedures, and facts. The teachers used writing tasks that mirrored this with their students. The teachers also had a limited definition of creativity in writing, and when they had students write creatively in science it was to add in fictional elements. Implications of this study include providing teachers with better models for how and why scientists write, including these models in more inquiry-based science lessons, and directly relating concepts of nature of science to elementary science writing.

An optically transparent and flexible memory with embedded gold nanoparticles in a polymethylsilsesquioxane dielectric

International Nuclear Information System (INIS)

Ooi, P.C.; Aw, K.C.; Gao, W.; Razak, K.A.

2013-01-01

In this work, we demonstrated a simple fabrication route towards an optically transparent and flexible memory device. The device is simple and consists of a metal/insulator/semiconductor structure; namely MIS. The preliminary MIS study with gold nanoparticles embedded between the polymethylsilsesquioxane layers was fabricated on p-Si substrate and the capacitance versus voltage measurements confirmed the charge trapped capability of the fabricated MIS memory device. Subsequently, an optically transparent and flexible MIS memory device made from indium–tin-oxide coated polyethylene terephthalate substrate and pentacene was used to replace the opaque p-Si substrate as the active layer. Current versus voltage (I–V) plot of the transparent and flexible device shows the presence of hysteresis. In an I–V plot, three distinct regions have been identified and the transport mechanisms are explained. The fabricated optically transparent and mechanically flexible MIS memory device can be programmed and erased multiple times, similar to a flash memory. Mechanical characterization to determine the robustness of the flexible memory device was also conducted but failed to establish any relationship in this preliminary work as the effect was random. Hence, more work is needed to understand the reliability of this device, especially when they are subjected to mechanical stress. - Highlights: ► An optically transparent and mechanically flexible memory is presented. ► Electrical characteristics show reprogrammable memory similar to flash memory. ► Transport mechanisms are proposed and explained. ► Mechanical bending tests are conducted

An optically transparent and flexible memory with embedded gold nanoparticles in a polymethylsilsesquioxane dielectric

Energy Technology Data Exchange (ETDEWEB)

Ooi, P.C. [Mechanical Engineering, The University of Auckland (New Zealand); Aw, K.C., E-mail: k.aw@auckland.ac.nz [Mechanical Engineering, The University of Auckland (New Zealand); Gao, W. [Chemical and Materials Engineering, The University of Auckland (New Zealand); Razak, K.A. [School of Materials and Mineral Resources Engineering, Universiti Sains (Malaysia); NanoBiotechnology Research and Innovation, INFORMM, Universiti Sains (Malaysia)

2013-10-01

In this work, we demonstrated a simple fabrication route towards an optically transparent and flexible memory device. The device is simple and consists of a metal/insulator/semiconductor structure; namely MIS. The preliminary MIS study with gold nanoparticles embedded between the polymethylsilsesquioxane layers was fabricated on p-Si substrate and the capacitance versus voltage measurements confirmed the charge trapped capability of the fabricated MIS memory device. Subsequently, an optically transparent and flexible MIS memory device made from indium–tin-oxide coated polyethylene terephthalate substrate and pentacene was used to replace the opaque p-Si substrate as the active layer. Current versus voltage (I–V) plot of the transparent and flexible device shows the presence of hysteresis. In an I–V plot, three distinct regions have been identified and the transport mechanisms are explained. The fabricated optically transparent and mechanically flexible MIS memory device can be programmed and erased multiple times, similar to a flash memory. Mechanical characterization to determine the robustness of the flexible memory device was also conducted but failed to establish any relationship in this preliminary work as the effect was random. Hence, more work is needed to understand the reliability of this device, especially when they are subjected to mechanical stress. - Highlights: ► An optically transparent and mechanically flexible memory is presented. ► Electrical characteristics show reprogrammable memory similar to flash memory. ► Transport mechanisms are proposed and explained. ► Mechanical bending tests are conducted.

Direct write of copper-graphene composite using micro-cold spray

Directory of Open Access Journals (Sweden)

Sameh Dardona

2016-08-01

Full Text Available Direct write of a new class of composite materials containing copper and graphene in the powder phase is described. The composite was synthesized using batch electroless plating of copper for various times onto Nano Graphene Platelets (NGP to control the amount of copper deposited within the loosely aggregated graphene powder. Copper deposition was confirmed by both Focused Ion Beam (FIB and Auger electron spectroscopic analysis. A micro-cold spray technique was used to deposit traces that are ∼230 μm wide and ∼5 μm thick of the formulated copper/graphene powder onto a glass substrate. The deposited traces were found to have good adhesion to the substrate with ∼65x the copper bulk resistivity.

Optimization of LOPA-based direct laser writing technique for fabrication of submicrometric polymer two- and three-dimensional structures

Science.gov (United States)

Do, Mai Trang; Li, Qinggele; Ledoux-Rak, Isabelle; Lai, Ngoc D.

2013-05-01

We demonstrate a novel and very simple method allowing very easy flexible fabrication of 2D and 3D submicrometric structures. By using a photosensitive polymer (SU8) possessing an ultralow one-photon absorption (LOPA) coefficient at the excition laser wavelength (532 nm) and a high numerical aperture (NA = 1.3, oil immersion) objective lens, various submicrometric structures with feature size as small as 150 nm have been successfully fabricated. We have further investigated the energy accumulation effect in LOPA direct laser writing when the structure lattice constant approaches the diffraction limit. In this case, a proximity correction, i.e., a compensation of the doses between different voxels, was applied, allowing to create uniform and submicrometric structures with a lattice constant as small as 400 nm. As compared to commonly used two-photon absorption microscopy, the LOPA method allows to simplify the experimental setup and also to minimize the photo-damaging or bleaching effect. The idea of using LOPA also opens a new and inexpensive way to optically address 3D structures, namely 3D fluorescence imaging and 3D data storage.

Direct detection of the optical field beyond single polarization mode.

Science.gov (United States)

Che, Di; Sun, Chuanbowen; Shieh, William

2018-02-05

Direct detection is traditionally regarded as a detection method that recovers only the optical intensity. Compared with coherent detection, it owns a natural advantage-the simplicity-but lacks a crucial capability of field recovery that enables not only the multi-dimensional modulation, but also the digital compensation of the fiber impairments linear with the optical field. Full-field detection is crucial to increase the capacity-distance product of optical transmission systems. A variety of methods have been investigated to directly detect the optical field of the single polarization mode, which normally sends a carrier traveling with the signal for self-coherent detection. The crux, however, is that any optical transmission medium supports at least two propagating modes (e.g. single mode fiber supports two polarization modes), and until now there is no direct detection that can recover the complete set of optical fields beyond one polarization, due to the well-known carrier fading issue after mode demultiplexing induced by the random mode coupling. To avoid the fading, direct detection receivers should recover the signal in an intensity space isomorphic to the optical field without loss of any degrees of freedom, and a bridge should be built between the field and its isomorphic space for the multi-mode field recovery. Based on this thinking, we propose, for the first time, the direct detection of dual polarization modes by a novel receiver concept, the Stokes-space field receiver (SSFR) and its extension, the generalized SSFR for multiple spatial modes. The idea is verified by a dual-polarization field recovery of a polarization-multiplexed complex signal over an 80-km single mode fiber transmission. SSFR can be applied to a much wider range of fields beyond optical communications such as coherent sensing and imaging, where simple field recovery without an extra local laser is desired for enhanced system performance.

A novel and simple fabrication method of embedded SU-8 micro channels by direct UV lithography

International Nuclear Information System (INIS)

Fu, C; Hung, C; Huang, H

2006-01-01

In this paper, we presents a novel and simple method to fabricate embedded micro channels. The method based on different light absorption properties of the SU-8 thick photoresist under different incident UV wavelengths. The channel structures are defined by the ordinary I-line, while the cover layer is patterned by the deep UV. Because the deep UV is obtained directly on the same aligner with a set of filter mirrors, the embedded channel can be easily produced without other rare facilities. Besides, the relationship between the thickness of the top layer and the exposure dose of the deep UV has been measured by an ingeniously designed experiment. The specific thickness of the top layer of the embedded micro channel can then be secured by the specific deep-UV exposure dose. Further more, many meaningful mechanical structures have been realized by this method, the material property of the top layer are also measured

Linearly polarized emission from an embedded quantum dot using nanowire morphology control.

Science.gov (United States)

Foster, Andrew P; Bradley, John P; Gardner, Kirsty; Krysa, Andrey B; Royall, Ben; Skolnick, Maurice S; Wilson, Luke R

2015-03-11

GaAs nanowires with elongated cross sections are formed using a catalyst-free growth technique. This is achieved by patterning elongated nanoscale openings within a silicon dioxide growth mask on a (111)B GaAs substrate. It is observed that MOVPE-grown vertical nanowires with cross section elongated in the [21̅1̅] and [1̅12] directions remain faithful to the geometry of the openings. An InGaAs quantum dot with weak radial confinement is realized within each nanowire by briefly introducing indium into the reactor during nanowire growth. Photoluminescence emission from an embedded nanowire quantum dot is strongly linearly polarized (typically >90%) with the polarization direction coincident with the axis of elongation. Linearly polarized PL emission is a result of embedding the quantum dot in an anisotropic nanowire structure that supports a single strongly confined, linearly polarized optical mode. This research provides a route to the bottom-up growth of linearly polarized single photon sources of interest for quantum information applications.

Laser direct-write of single microbeads into spatially-ordered patterns

International Nuclear Information System (INIS)

Phamduy, Theresa B; Schiele, Nathan R; Corr, David T; Chrisey, Douglas B; Raof, Nurazhani Abdul; Xie Yubing; Yan Zijie; Huang Yong

2012-01-01

Fabrication of heterogeneous microbead patterns on a bead-by-bead basis promotes new opportunities for sensors, lab-on-a-chip technology and cell-culturing systems within the context of customizable constructs. Laser direct-write (LDW) was utilized to target and deposit solid polystyrene and stem cell-laden alginate hydrogel beads into computer-programmed patterns. We successfully demonstrated single-bead printing resolution and fabricated spatially-ordered patterns of microbeads. The probability of successful microbead transfer from the ribbon surface increased from 0 to 80% with decreasing diameter of 600 to 45 µm, respectively. Direct-written microbeads retained spatial pattern registry, even after 10 min of ultrasonication treatment. SEM imaging confirmed immobilization of microbeads. Viability of cells encapsulated in transferred hydrogel microbeads achieved 37 ± 11% immediately after the transfer process, whereas randomly-patterned pipetted control beads achieved a viability of 51 ± 25%. Individual placement of >10 µm diameter microbeads onto planar surfaces has previously been unattainable. We have demonstrated LDW as a valuable tool for the patterning of single, micrometer-diameter beads into spatially-ordered patterns. (paper)

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

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R. Brian Jenkins

2017-01-01

Full Text Available Fiber Bragg grating (FBG temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors.

Science.gov (United States)

Jenkins, R Brian; Joyce, Peter; Mechtel, Deborah

2017-01-27

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

Commentary on "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games" by Almond et al.

Science.gov (United States)

Timms, Mike

2014-01-01

In his commentary on "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games" by Almond et al., Mike Timms writes that his own research has involved the use of embedded assessments using simulations in interactive learning environments, and the Evidence Centered Design (ECD) approach has provided a solid…

“Beating speckles” via electrically-induced vibrations of Au nanorods embedded in sol-gel

Science.gov (United States)

Ritenberg, Margarita; Beilis, Edith; Ilovitsh, Asaf; Barkai, Zehava; Shahmoon, Asaf; Richter, Shachar; Zalevsky, Zeev; Jelinek, Raz

2014-01-01

Generation of macroscopic phenomena through manipulating nano-scale properties of materials is among the most fundamental goals of nanotechnology research. We demonstrate cooperative “speckle beats” induced through electric-field modulation of gold (Au) nanorods embedded in a transparent sol-gel host. Specifically, we show that placing the Au nanorod/sol-gel matrix in an alternating current (AC) field gives rise to dramatic modulation of incident light scattered from the material. The speckle light patterns take form of “beats”, for which the amplitude and frequency are directly correlated with the voltage and frequency, respectively, of the applied AC field. The data indicate that the speckle beats arise from localized vibrations of the gel-embedded Au nanorods, induced through the interactions between the AC field and the electrostatically-charged nanorods. This phenomenon opens the way for new means of investigating nanoparticles in constrained environments. Applications in electro-optical devices, such as optical modulators, movable lenses, and others are also envisaged. PMID:24413086

Droplet-Assisted Laser Direct Nanoscale Writing on Silicon

Directory of Open Access Journals (Sweden)

Yuan-Jen Chang

2016-03-01

Full Text Available Nano-structuring using laser direct writing technology has shown great potential for industrial applications. A novel application of water droplets to this technology is proposed in this paper. With a hydrophobic layer and a controlled substrate temperature, a layer of randomly distributed water droplets with a high contact angle is formed on the substrate. These liquid droplets can be used as lenses to enhance the laser intensity at the bottom of the droplets. As a result, nanoscale holes can be fabricated on the substrate by controlling the laser energy density. We successfully fabricated holes with a diameter of 600 nm at a substrate temperature of 12 ∘C and a power density of 1.2 × 108 W/cm2 in our experiments. We also found that the hole diameter was around a ninth of the water droplet diameter. Meanwhile, the machined holes are not affected much by the focal length of the lens, but a hole with less than 100 nm in diameter at the center was observed.

Technical Writing 1987: Galloping Off in at Least Two Directions.

Science.gov (United States)

Stohrer, Freda F.

Technical writing instructors generally agree about the absolute need for communication skills throughout the technological work place, but a survey of technical writing journal articles shows a lack of focus on ways to address business's needs for on-the-job literacy. One major advance within the profession in recent years has been the…

Avant-garde femtosecond laser writing

OpenAIRE

Kazansky, Peter G.; Beresna, Martynas; Shimotsuma, Yasuhiko; Hirao, Kazuyuki; Svirko, Yuri P.; Aktürk, Selcuk

2010-01-01

Recently discovered phenomena of quill and non-reciprocal femtosecond laser writing in glasses and crystals are reviewed. Common beliefs that laser writing does not change when reversing beam scan or propagation direction are challenged.

Performance Characterization of an xy-Stage Applied to Micrometric Laser Direct Writing Lithography

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Juan Jaramillo

2017-01-01

Full Text Available This article concerns the characterization of the stability and performance of a motorized stage used in laser direct writing lithography. The system was built from commercial components and commanded by G-code. Measurements use a pseudo-periodic-pattern (PPP observed by a camera and image processing is based on Fourier transform and phase measurement methods. The results report that the built system has a stability against vibrations determined by peak-valley deviations of 65 nm and 26 nm in the x and y directions, respectively, with a standard deviation of 10 nm in both directions. When the xy-stage is in movement, it works with a resolution of 0.36 μm, which is an acceptable value for most of research and development (R and D microtechnology developments in which the typical feature size used is in the micrometer range.

Performance Characterization of an xy-Stage Applied to Micrometric Laser Direct Writing Lithography.

Science.gov (United States)

Jaramillo, Juan; Zarzycki, Artur; Galeano, July; Sandoz, Patrick

2017-01-31

This article concerns the characterization of the stability and performance of a motorized stage used in laser direct writing lithography. The system was built from commercial components and commanded by G-code. Measurements use a pseudo-periodic-pattern (PPP) observed by a camera and image processing is based on Fourier transform and phase measurement methods. The results report that the built system has a stability against vibrations determined by peak-valley deviations of 65 nm and 26 nm in the x and y directions, respectively, with a standard deviation of 10 nm in both directions. When the xy-stage is in movement, it works with a resolution of 0.36 μm, which is an acceptable value for most of research and development (R and D) microtechnology developments in which the typical feature size used is in the micrometer range.

Femtosecond laser direct writing of gratings and waveguides in high quantum efficiency erbium-doped Baccarat glass

International Nuclear Information System (INIS)

Vishnubhatla, K C; Kumar, R Sai Santosh; Rao, D Narayana; Rao, S Venugopal; Osellame, R; Ramponi, R; Bhaktha, S N B; Mattarelli, M; Montagna, M; Turrell, S; Chiappini, A; Chiasera, A; Ferrari, M; Righini, G C

2009-01-01

The femtosecond laser direct writing technique was employed to inscribe gratings and waveguides in high quantum efficiency erbium-doped Baccarat glass. Using the butt coupling technique, a systematic study of waveguide loss with respect to input pulse energy and writing speed was performed to achieve the best waveguide with low propagation loss (PL). By pumping at 980 nm, we observed signal enhancement in these active waveguides in the telecom spectral region. The refractive index change was smooth and we estimated it to be ∼10 -3 . The high quantum efficiency (∼80%) and a best PL of ∼0.9 dB cm -1 combined with signal enhancement makes Baccarat glass a potential candidate for application in photonics.

Talking Grammatically: L1 Adolescent Metalinguistic Reflection on Writing

Science.gov (United States)

Watson, Annabel Mary; Newman, Ruth Malka Charlotte

2017-01-01

This study investigated the metalinguistic reflections of 12 students, aged 14-15 years, undertaking a unit of work focused on reading and writing non-fiction. The unit embedded contextualised grammar teaching into preparation for English Language examinations. Students were interviewed twice, with prompts to discuss a sample of argument text in…

Nanoscale Engineering in VO2 Nanowires via Direct Electron Writing Process.

Science.gov (United States)

Zhang, Zhenhua; Guo, Hua; Ding, Wenqiang; Zhang, Bin; Lu, Yue; Ke, Xiaoxing; Liu, Weiwei; Chen, Furong; Sui, Manling

2017-02-08

Controlling phase transition in functional materials at nanoscale is not only of broad scientific interest but also important for practical applications in the fields of renewable energy, information storage, transducer, sensor, and so forth. As a model functional material, vanadium dioxide (VO 2 ) has its metal-insulator transition (MIT) usually at a sharp temperature around 68 °C. Here, we report a focused electron beam can directly lower down the transition temperature of a nanoarea to room temperature without prepatterning the VO 2 . This novel process is called radiolysis-assisted MIT (R-MIT). The electron beam irradiation fabricates a unique gradual MIT zone to several times of the beam size in which the temperature-dependent phase transition is achieved in an extended temperature range. The gradual transformation zone offers to precisely control the ratio of metal/insulator phases. This direct electron writing technique can open up an opportunity to precisely engineer nanodomains of diversified electronic properties in functional material-based devices.

Direct Wafer Bonding and Its Application to Waveguide Optical Isolators

Directory of Open Access Journals (Sweden)

Ryohei Takei

2012-05-01

Full Text Available This paper reviews the direct bonding technique focusing on the waveguide optical isolator application. A surface activated direct bonding technique is a powerful tool to realize a tight contact between dissimilar materials. This technique has the potential advantage that dissimilar materials are bonded at low temperature, which enables one to avoid the issue associated with the difference in thermal expansion. Using this technique, a magneto-optic garnet is successfully bonded on silicon, III-V compound semiconductors and LiNbO₃. As an application of this technique, waveguide optical isolators are investigated including an interferometric waveguide optical isolator and a semileaky waveguide optical isolator. The interferometric waveguide optical isolator that uses nonreciprocal phase shift is applicable to a variety of waveguide platforms. The low refractive index of buried oxide layer in a silicon-on-insulator (SOI waveguide enhances the magneto-optic phase shift, which contributes to the size reduction of the isolator. A semileaky waveguide optical isolator has the advantage of large fabrication-tolerance as well as a wide operation wavelength range.

Direct Wafer Bonding and Its Application to Waveguide Optical Isolators.

Science.gov (United States)

Mizumoto, Tetsuya; Shoji, Yuya; Takei, Ryohei

2012-05-24

This paper reviews the direct bonding technique focusing on the waveguide optical isolator application. A surface activated direct bonding technique is a powerful tool to realize a tight contact between dissimilar materials. This technique has the potential advantage that dissimilar materials are bonded at low temperature, which enables one to avoid the issue associated with the difference in thermal expansion. Using this technique, a magneto-optic garnet is successfully bonded on silicon, III-V compound semiconductors and LiNbO₃. As an application of this technique, waveguide optical isolators are investigated including an interferometric waveguide optical isolator and a semileaky waveguide optical isolator. The interferometric waveguide optical isolator that uses nonreciprocal phase shift is applicable to a variety of waveguide platforms. The low refractive index of buried oxide layer in a silicon-on-insulator (SOI) waveguide enhances the magneto-optic phase shift, which contributes to the size reduction of the isolator. A semileaky waveguide optical isolator has the advantage of large fabrication-tolerance as well as a wide operation wavelength range.

Media effects on the optical absorption spectra of silver clusters embedded in rara gas matrices

International Nuclear Information System (INIS)

Fedrigo, S.; Harbich, W.; Buttet, J.

1993-01-01

The optical absorption of small mass selected Ag n -clusters (n=7, 11, 15, 21) embedded in solid Ar, Kr and Xe has been measured. The absorption spectra show 1 to 3 major peaks between 3 and 4.5 eV, depending on the cluster size. Changing the matrix gas Ar→Kr→Xe induces a redshift which is comparable for all sizes studied and does not affect the main structure of the absorption spectra. We propose a scheme to estimate the gas phase value of the absorption energies which is in fair agreement with an estimation obtained by a simple model based on a Drude metal. (author). 10 refs, 2 figs

Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications

International Nuclear Information System (INIS)

Akhter, Perveen; Huang, Mengbing; Spratt, William; Kadakia, Nirag; Amir, Faisal

2015-01-01

Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics

The Conductive Silver Nanowires Fabricated by Two-beam Laser Direct Writing on the Flexible Sheet

Science.gov (United States)

He, Gui-Cang; Zheng, Mei-Ling; Dong, Xian-Zi; Jin, Feng; Liu, Jie; Duan, Xuan-Ming; Zhao, Zhen-Sheng

2017-02-01

Flexible electrically conductive nanowires are now a key component in the fields of flexible devices. The achievement of metal nanowire with good flexibility, conductivity, compact and smooth morphology is recognized as one critical milestone for the flexible devices. In this study, a two-beam laser direct writing system is designed to fabricate AgNW on PET sheet. The minimum width of the AgNW fabricated by this method is 187 ± 34 nm with the height of 84 ± 4 nm. We have investigated the electrical resistance under different voltages and the applicable voltage per meter range is determined to be less than 7.5 × 103 V/m for the fabricated AgNW. The flexibility of the AgNW is very excellent, since the resistance only increases 6.63% even after the stretched bending of 2000 times at such a small bending radius of 1.0 mm. The proposed two-beam laser direct writing is an efficient method to fabricate AgNW on the flexible sheet, which could be applied in flexible micro/nano devices.

Anisotropic surroundings effects on photo absorption of partially embedded Au nanospheroids in silica glass substrate

Energy Technology Data Exchange (ETDEWEB)

Meng, Xuan; Shibayama, Tamaki, E-mail: shiba@qe.eng.hokudai.ac.jp; Watanabe, Seiichi [Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060–8628 (Japan); Yu, Ruixuan; Ishioka, Junya [Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060–8628 (Japan)

2015-02-15

The influence of a directly adjacent or an anisotropic surrounding medium alters the plasmonic properties of a nanoparticle because it provides a mechanism for symmetry breaking of the scattering. Given the success of ion irradiation induced embedment of rigid metallic nanospheroids into amorphous substrate, it is possible to examine the effect of the silica glass substrate on the plasmonic properties of these embedded nanospheroids. In this work presented here, discrete dipole approximation (DDA) calculations for the Au nanospheroids’ optical properties were performed based on 3–dimensional (3D) configuration extracted from planar SEM micrographs and cross–sectional TEM micrographs of the Au nanospheroids partially embedded in the silica glass, and the well–matched simulations with respect to the experimental measurements could demonstrate the dielectric constant at the near surface of silica glass decreased after Ar–ion irradiation.

Three-dimensionally embedded indium tin oxide (ITO) films in photosensitive glass: a transparent and conductive platform for microdevices

International Nuclear Information System (INIS)

Beke, S.; Sugioka, K.; Midorikawa, K.; Koroesi, L.; Dekany, I.

2011-01-01

A new method for embedding transparent and conductive two- and three-dimensional microstructures in glass is presented. We show that the internal surface of hollow structures fabricated by femtosecond-laser direct writing inside the photosensitive glass can be coated by indium tin oxide (Sn-doped In 2 O 3 , ITO) using a sol-gel process. The idea of combining two transparent materials with different electrical properties, i.e., insulating and conductive, is very promising and hence it opens new prospects in manufacturing cutting edge microdevices, such as lab-on-a-chips (LOCs) and microelectromechanical systems (MEMS). (orig.)

Assurance of Learning for Principles of Marketing Students: A Longitudinal Study of a Course-Embedded Direct Assessment

Science.gov (United States)

LaFleur, Elizabeth K.; Babin, Laurie A.; Lopez, Tara Burnthorne

2009-01-01

This article describes the process one marketing faculty followed to demonstrate assurance of learning for marketing students and presents longitudinal results associated with a course-embedded direct assessment device in the Principles of Marketing course. The process follows closely the Association to Advance Collegiate Schools of Business…

Natural Fe3O4 nanoparticles embedded zinc–tellurite glasses: Polarizability and optical properties

International Nuclear Information System (INIS)

Widanarto, W.; Sahar, M.R.; Ghoshal, S.K.; Arifin, R.; Rohani, M.S.; Hamzah, K.; Jandra, M.

2013-01-01

Modifying the optical behavior of zinc–tellurite glass by embedding magnetic nanoparticles has implication in nanophotonics. A series of zinc–tellurite glasses containing natural Fe 3 O 4 nanoparticles with composition (80 − x)TeO 2 ·xFe 3 O 4 ·20ZnO (0 ≤ x ≤ 2) in mol% are synthesized by melt quenching method and their optical properties are investigated using FTIR and UV–vis–NIR spectroscopies. Lorentz–Lorenz relations are exploited to determine the refractive index, molar refraction and electronic polarizability. The sharp absorption peaks of FTIR spectra show a shift from 667 cm −1 to 671 cm −1 in the presence of nanoparticles that increase the non-bridging oxygen, confirmed by the intensity change of the TeO 3 peak at 752 cm −1 . A new peak around 461 cm −1 is also observed which is attributed to the band characteristic of covalent Fe–O linkages. A decrease in the Urbach energy as much as 0.122 eV and the optical energy band gap with the increase of Fe 3 O 4 concentration (0.5–1.0 mol%) is evidenced. Electronic polarizability of the glasses increases with increasing Fe 3 O 4 nanoparticles concentration up to 1 mol%. Interestingly, the polarizability tends to decrease with the further increase of Fe 3 O 4 concentration at 2 mol%. The role of magnetic nanoparticles in influencing the structural and optical behavior are examined and understood. - Highlights: ► Incorporation of natural Fe 3 O 4 nanoparticles into the zinc–tellurite glass. ► Influence of magnetic nanoparticles in modifying structure and optical properties. ► Enhancement of refraction index and change in electronic polarizability

The Word Writing CAFE: Assessing Student Writing for Complexity, Accuracy, and Fluency

Science.gov (United States)

Leal, Dorothy J.

2005-01-01

The Word Writing CAFE is a new assessment tool designed for teachers to evaluate objectively students' word-writing ability for fluency, accuracy, and complexity. It is designed to be given to the whole class at one time. This article describes the development of the CAFE and provides directions for administering and scoring it. The author also…

Directly writing resistor, inductor and capacitor to composite functional circuits: a super-simple way for alternative electronics.

Directory of Open Access Journals (Sweden)

Yunxia Gao

Full Text Available BACKGROUND: The current strategies for making electronic devices are generally time, water, material and energy consuming. Here, the direct writing of composite functional circuits through comprehensive use of GaIn10-based liquid metal inks and matching material is proposed and investigated, which is a rather easy going and cost effective electronics fabrication way compared with the conventional approaches. METHODS: Owing to its excellent adhesion and electrical properties, the liquid metal ink was demonstrated as a generalist in directly making various basic electronic components such as planar resistor, inductor and capacitor or their combination and thus composing circuits with expected electrical functions. For a precise control of the geometric sizes of the writing, a mask with a designed pattern was employed and demonstrated. Mechanisms for justifying the chemical components of the inks and the magnitudes of the target electronic elements so as to compose various practical circuits were disclosed. RESULTS: Fundamental tests on the electrical components including capacitor and inductor directly written on paper with working time up to 48 h and elevated temperature demonstrated their good stability and potential widespread adaptability especially when used in some high frequency circuits. As the first proof-of-concept experiment, a typical functional oscillating circuit including an integrated chip of 74HC04 with a supply voltage of 5 V, a capacitor of 10 nF and two resistors of 5 kΩ and 1 kΩ respectively was directly composed on paper through integrating specific electrical elements together, which presented an oscillation frequency of 8.8 kHz. CONCLUSIONS: The present method significantly extends the roles of the metal ink in recent works serving as only a single electrical conductor or interconnecting wires. It opens the way for directly writing out complex functional circuits or devices on different substrates. Such circuit

Model of diffusion-assisted direct laser writing by means of nanopolymerization in the presence of radical quencher

International Nuclear Information System (INIS)

Pikulin, Alexander; Bityurin, Nikita; Sokolov, Viktor I.

2015-01-01

Diffusion-assisted direct laser writing (DA-DLW) by multiphoton polymerization has been recently shown to be one of the most promising methods for the high-resolution 3D nanofabrication [I. Sakellari, et al., ACS Nano 6, 2302 (2012)]. The improvement of the writing spatial resolution has been observed under certain conditions when the mobile radical quencher (polymerization inhibitor) is added to the photosensitive composition. In this work, we present a theoretical study of this method, focusing on the resolution capabilities and optimal writing parameters. The laser beam absorption in the polymerizable composition causes the localized depletion of the quencher molecules. If the quencher depletion is balanced by its diffusion from the outside of the focal volume, the quasi-stationary non-equillibrium concentration spatial profile with zero minimum can be obtained. The polymer is then effectively formed only in the domain where the quencher is depleted. The spatially-distributed quencher, in this case, has the effect similar to that of the vortex beam in STimulated Emission Microscopy (STED)

Hybrid 2D patterning using UV laser direct writing and aerosol jet printing of UV curable polydimethylsiloxane

Science.gov (United States)

Obata, Kotaro; Schonewille, Adam; Slobin, Shayna; Hohnholz, Arndt; Unger, Claudia; Koch, Jürgen; Suttmann, Oliver; Overmeyer, Ludger

2017-09-01

The hybrid technique of aerosol jet printing and ultraviolet (UV) laser direct writing was developed for 2D patterning of thin film UV curable polydimethylsiloxane (PDMS). A dual atomizer module in an aerosol jet printing system generated aerosol jet streams from material components of the UV curable PDMS individually and enables the mixing in a controlled ratio. Precise control of the aerosol jet printing achieved the layer thickness of UV curable PDMS as thin as 1.6 μm. This aerosol jet printing system is advantageous because of its ability to print uniform thin-film coatings of UV curable PDMS on planar surfaces as well as free-form surfaces without the use of solvents. In addition, the hybrid 2D patterning using the combination of UV laser direct writing and aerosol jet printing achieved selective photo-initiated polymerization of the UV curable PDMS layer with an X-Y resolution of 17.5 μm.

Optically sensitive devices based on Pt nano particles fabricated by atomic layer deposition and embedded in a dielectric stack

Energy Technology Data Exchange (ETDEWEB)

Mikhelashvili, V.; Padmanabhan, R.; Eisenstein, G. [Electrical Engineering Department, Technion, Haifa 3200 (Israel); Russell Berrie Nanotechnology Institute, Technion, Haifa 3200 (Israel); Meyler, B.; Yofis, S.; Weindling, S.; Salzman, J. [Electrical Engineering Department, Technion, Haifa 3200 (Israel); Atiya, G.; Cohen-Hyams, Z.; Kaplan, W. D. [Department of Material Science and Engineering, Technion, Haifa 3200 (Israel); Russell Berrie Nanotechnology Institute, Technion, Haifa 3200 (Israel); Ankonina, G. [Russell Berrie Nanotechnology Institute, Technion, Haifa 3200 (Israel); Photovoltaic Laboratory, Technion, Haifa 3200 (Israel)

2015-10-07

We report a series of metal insulator semiconductor devices with embedded Pt nano particles (NPs) fabricated using a low temperature atomic layer deposition process. Optically sensitive nonvolatile memory cells as well as optical sensors: (i) varactors, whose capacitance-voltage characteristics, nonlinearity, and peak capacitance are strongly dependent on illumination intensity; (ii) highly linear photo detectors whose responsivity is enhanced due to the Pt NPs. Both single devices and back to back pairs of diodes were used. The different configurations enable a variety of functionalities with many potential applications in biomedical sensing, environmental surveying, simple imagers for consumer electronics and military uses. The simplicity and planar configuration of the proposed devices makes them suitable for standard CMOS fabrication technology.

Optically sensitive devices based on Pt nano particles fabricated by atomic layer deposition and embedded in a dielectric stack

International Nuclear Information System (INIS)

Mikhelashvili, V.; Padmanabhan, R.; Eisenstein, G.; Meyler, B.; Yofis, S.; Weindling, S.; Salzman, J.; Atiya, G.; Cohen-Hyams, Z.; Kaplan, W. D.; Ankonina, G.

2015-01-01

We report a series of metal insulator semiconductor devices with embedded Pt nano particles (NPs) fabricated using a low temperature atomic layer deposition process. Optically sensitive nonvolatile memory cells as well as optical sensors: (i) varactors, whose capacitance-voltage characteristics, nonlinearity, and peak capacitance are strongly dependent on illumination intensity; (ii) highly linear photo detectors whose responsivity is enhanced due to the Pt NPs. Both single devices and back to back pairs of diodes were used. The different configurations enable a variety of functionalities with many potential applications in biomedical sensing, environmental surveying, simple imagers for consumer electronics and military uses. The simplicity and planar configuration of the proposed devices makes them suitable for standard CMOS fabrication technology

Direct writing of large-area micro/nano-structural arrays on single crystalline germanium substrates using femtosecond lasers

Science.gov (United States)

Li, Lin; Wang, Jun

2017-06-01

A direct writing technique for fabricating micro/nano-structural arrays without using a multi-scanning process, multi-beam interference, or any assisted microlens arrays is reported. Various sub-wavelength micro/nano-structural arrays have been directly written on single crystalline germanium substrate surfaces using femtosecond laser pulses. The evolution of the multiscale surface morphology from periodic micro/nano-structures to V-shaped microgrooves has been achieved, and the relationship between array characteristics and laser polarization directions has been discussed. The self-organization model agrees well with the experimental results in this study.

Avant-Garde Ultrafast Laser Writing

Directory of Open Access Journals (Sweden)

Kazansky P. G.

2013-11-01

Full Text Available Ultrafast laser processing of transparent materials reveals new phenomena. Reviewed, are recent demonstrations of 5D optical memory, vortex polarization and Airy beam converters employing self-assembled nanostructuring, ultrafast laser calligraphy and polarization writing control using pulses with tilted front.

Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring.

Science.gov (United States)

Sartiano, Demetrio; Sales, Salvador

2017-12-13

The aim of this paper is to report the design of a low-cost plastic optical fiber (POF) pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is implemented using Arduino board, standard LEDs for optical communication in POF (λ = 645 nm) and a silicon light sensor. The Super ESKA ® plastic fibers were used to implement the fiber intensity sensor, arranged in a 4 × 4 matrix. During the breathing cycles, the force transmitted from the lungs to the thorax is in the order of tens of Newtons, and the respiration rate is of one breath every 2-5 s (0.2-0.5 Hz). The sensor has a resolution of force applied on a single point of 2.2-4.5%/N on the normalized voltage output, and a bandwidth of 10 Hz, it is then suitable to monitor the respiration movements. Another issue to be addressed is the presence of hysteresis over load cycles. The sensor was loaded cyclically to estimate the drift of the system, and the hysteresis was found to be negligible.

Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring

Directory of Open Access Journals (Sweden)

Demetrio Sartiano

2017-12-01

Full Text Available The aim of this paper is to report the design of a low-cost plastic optical fiber (POF pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is implemented using Arduino board, standard LEDs for optical communication in POF (λ = 645 nm and a silicon light sensor. The Super ESKA® plastic fibers were used to implement the fiber intensity sensor, arranged in a 4 × 4 matrix. During the breathing cycles, the force transmitted from the lungs to the thorax is in the order of tens of Newtons, and the respiration rate is of one breath every 2–5 s (0.2–0.5 Hz. The sensor has a resolution of force applied on a single point of 2.2–4.5%/N on the normalized voltage output, and a bandwidth of 10 Hz, it is then suitable to monitor the respiration movements. Another issue to be addressed is the presence of hysteresis over load cycles. The sensor was loaded cyclically to estimate the drift of the system, and the hysteresis was found to be negligible.

YBa2Cu3O7 nanobridges fabricated by direct-write electron beam lithography

International Nuclear Information System (INIS)

Wendt, J.R.; Martens, J.S.; Ashby, C.I.H.; Plut, T.A.; Hietala, V.M.; Tigges, C.P.; Ginley, D.S.; Siegal, M.P.; Phillips, J.M.; Hohenwarter, G.K.G.

1992-01-01

A direct method for nondamaging, nanometer-scale patterning of high T c superconductor thin films is presented. We have fabricated superconducting nanobridges in high-quality, epitaxial thin-film YBa 2 Cu 3 O 7 (YBCO) by combining direct-write electron beam lithography and an improved aqueous etchant. Weak links with both length and width dimensions less than 20 nm have exhibited critical currents at 77 K of 4--20 μA and I cRn products of 10--100 μV which compare favorably with results for other YBCO junction technologies. We have used this technique in the fabrication of a shock-wave pulse former as an initial demonstration of its applicability to monolithic superconductive electronics

Development of an Embedded Solar Tracker using Compact RIO

Energy Technology Data Exchange (ETDEWEB)

Oh, Seung Jin; Lee, Yoon Joon; Chun, Won Gee [Jeju National University, Jeju (Korea, Republic of)

2011-08-15

An embedded two-axis solar tracking system using LabVIEW to write the operation and control algorithms was developed for enhancing solar energy utilization. The system consists of a real-time processor, two motion- control modules, two step drives, two step motors, feedback devices, and other accessories needed for functional stability. The real-time processor allows the solar tracker to be used as a stand-alone, real-time system that can operate automatically without any external control. The system combines two different solar tracking methods: the optical method and the astronomical method. CdS sensors are employed to continuously generate feedback signals to the controller, ensuring high-precision solar tracking even under adverse conditions. CdS sensor is a resistor whose resistance decreases with increasing incident light intensity. A database of solar altitude, azimuth, and sunrise and sunset times is provided by this solar tracking system. Other solar trackers operating in an astronomical method may access and use this database over the Internet. Solar position and sunrise and sunset times in the database were compared with those of the Astronomical Applications Department of the U.S. Naval Observatory. The differences were found to be negligible.

Development of an Embedded Solar Tracker using Compact RIO

International Nuclear Information System (INIS)

Oh, Seung Jin; Lee, Yoon Joon; Chun, Won Gee

2011-01-01

An embedded two-axis solar tracking system using LabVIEW to write the operation and control algorithms was developed for enhancing solar energy utilization. The system consists of a real-time processor, two motion- control modules, two step drives, two step motors, feedback devices, and other accessories needed for functional stability. The real-time processor allows the solar tracker to be used as a stand-alone, real-time system that can operate automatically without any external control. The system combines two different solar tracking methods: the optical method and the astronomical method. CdS sensors are employed to continuously generate feedback signals to the controller, ensuring high-precision solar tracking even under adverse conditions. CdS sensor is a resistor whose resistance decreases with increasing incident light intensity. A database of solar altitude, azimuth, and sunrise and sunset times is provided by this solar tracking system. Other solar trackers operating in an astronomical method may access and use this database over the Internet. Solar position and sunrise and sunset times in the database were compared with those of the Astronomical Applications Department of the U.S. Naval Observatory. The differences were found to be negligible

Re-contextualising academic writing in English

DEFF Research Database (Denmark)

Larsen, Sanne

six focal students’ challenges in re-contextualising themselves as writers in English in a new university environment, data were generated from regular interviews with the participants over one semester, supplemented by questionnaires, documentary evidence, and observational data. Analyses building......’ experiences as writers of English, manifested in three main areas of concern: ideational, linguistic, and interpersonal. These writing concerns were embedded in more global processes of establishing academic continuity and in managing English-mediated instruction and learning in the English...

Propagation properties of silver nanowires embedded in a substrate with gain

DEFF Research Database (Denmark)

Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi

2016-01-01

The transmittance, reflectance and absorption of silver nanowires metamaterial embedded into a semiconductor matrix with optical gain are numerically investigated. Metamaterials may suffer from appreciable dissipative losses which are inherent for all plasmonic structures. The losses can signific......The transmittance, reflectance and absorption of silver nanowires metamaterial embedded into a semiconductor matrix with optical gain are numerically investigated. Metamaterials may suffer from appreciable dissipative losses which are inherent for all plasmonic structures. The losses can...... significantly be reduced by introducing optical gain in the dielectric matrix by placing atomic or molecular impurities which are pumped by an external light source to create a population inversion. We numerically analyzed the optical properties when the semiconductor host material represents a gain medium. We...

The art of femtosecond laser writing

OpenAIRE

Kazansky, Peter G.; Yang, Weijia; Shimotsuma, Yasuhiko; Hirao, Kazuyuki; Arai, Alan; Svirko, Yuri P.

2009-01-01

Common beliefs that laser writing does not change when reversing beam scan or propagation direction are challenged. Recently discovered phenomena of quill and non-reciprocal femtosecond laser writing in glasses and crystals are reviewed

Minimizing embedding impact in steganography using trellis-coded quantization

Science.gov (United States)

Filler, Tomáš; Judas, Jan; Fridrich, Jessica

2010-01-01

In this paper, we propose a practical approach to minimizing embedding impact in steganography based on syndrome coding and trellis-coded quantization and contrast its performance with bounds derived from appropriate rate-distortion bounds. We assume that each cover element can be assigned a positive scalar expressing the impact of making an embedding change at that element (single-letter distortion). The problem is to embed a given payload with minimal possible average embedding impact. This task, which can be viewed as a generalization of matrix embedding or writing on wet paper, has been approached using heuristic and suboptimal tools in the past. Here, we propose a fast and very versatile solution to this problem that can theoretically achieve performance arbitrarily close to the bound. It is based on syndrome coding using linear convolutional codes with the optimal binary quantizer implemented using the Viterbi algorithm run in the dual domain. The complexity and memory requirements of the embedding algorithm are linear w.r.t. the number of cover elements. For practitioners, we include detailed algorithms for finding good codes and their implementation. Finally, we report extensive experimental results for a large set of relative payloads and for different distortion profiles, including the wet paper channel.

Reading and writing direction effects on the aesthetic appreciation of photographs.

Science.gov (United States)

Chahboun, Sobh; Flumini, Andrea; Pérez González, Carmen; McManus, I Chris; Santiago, Julio

2017-05-01

Does reading and writing direction (RWD) influence the aesthetic appreciation of photography? Pérez González showed that nineteenth-century Iranian and Spanish professional photographers manifest lateral biases linked to RWD in their compositions. The present study aimed to test whether a population sample showed similar biases. Photographs with left-to-right (L-R) and right-to-left (R-L) directionality were selected from Pérez González's collections and presented in both original and mirror-reversed forms to Spanish (L-R readers) and Moroccan (R-L readers) participants. In Experiment 1, participants rated each picture for its aesthetic pleasingness. The results showed neither effects of lateral organization nor interactions with RWD. In Experiment 2, each picture and its mirror version were presented together and participants chose the one they liked better. Spaniards preferred rightward versions and Moroccans preferred leftward versions. RWD therefore affects aesthetic impressions of photography in our participants when people pay attention to the lateral spatial dimension of pictures. The observed directional aesthetic preferences were not sensitive to the sex of the model in the photographs, failing to support expectations from the hypotheses of emotionality and agency. Preferences were attributable to the interaction between general scanning strategies and scanning habits linked to RWD.

Static and ultrafast optical properties of nanolayered composites. Gold nanoparticles embedded in polyelectrolytes

Energy Technology Data Exchange (ETDEWEB)

Kiel, Mareike

2012-08-16

In the course of this thesis gold nanoparticle/polyelectrolyte multilayer structures were prepared, characterized, and investigated according to their static and ultrafast optical properties. Using the dip-coating or spin-coating layer-by-layer deposition method, gold-nanoparticle layers were embedded in a polyelectrolyte environment with high structural perfection. Typical structures exhibit four repetition units, each consisting of one gold-particle layer and ten double layers of polyelectrolyte (cationic+anionic polyelectrolyte). The structures were characterized by X-ray reflectivity measurements, which reveal Bragg peaks up to the seventh order, evidencing the high stratification of the particle layers. In the same measurements pronounced Kiessig fringes were observed, which indicate a low global roughness of the samples. Atomic force microscopy (AFM) images verified this low roughness, which results from the high smoothing capabilities of polyelectrolyte layers. This smoothing effect facilitates the fabrication of stratified nanoparticle/polyelectrolyte multilayer structures, which were nicely illustrated in a transmission electron microscopy image. The samples' optical properties were investigated by static spectroscopic measurements in the visible and UV range. The measurements revealed a frequency shift of the reflectance and of the plasmon absorption band, depending on the thickness of the polyelectrolyte layers that cover a nanoparticle layer. When the covering layer becomes thicker than the particle interaction range, the absorption spectrum becomes independent of the polymer thickness. However, the reflectance spectrum continues shifting to lower frequencies (even for large thicknesses). The range of plasmon interaction was determined to be in the order of the particle diameter for 10 nm, 20 nm, and 150 nm particles. The transient broadband complex dielectric function of a multilayer structure was determined experimentally by ultrafast pump

Analysis and experimental study on the strain transfer mechanism of an embedded basalt fiber-encapsulated fiber Bragg grating sensor

Science.gov (United States)

Zhang, Zhenglin; Wang, Yuan; Sun, Yangyang; Zhang, Qinghua; You, Zewei; Huang, Xiaodi

2017-01-01

The precision of the encapsulated fiber optic sensor embedded into a host suffers from the influences of encapsulating materials. Furthermore, an interface transfer effect of strain sensing exists. This study uses an embedded basalt fiber-encapsulated fiber Bragg grating (FBG) sensor as the research object to derive an expression in a multilayer interface strain transfer coefficient by considering the mechanical properties of the host material. The direct impact of the host material on the strain transfer at an embedded multipoint continuous FBG (i.e., multiple gratings written on a single optical fiber) monitoring strain sensor, which was self-developed and encapsulated with basalt fiber, is studied to present the strain transfer coefficients corresponding to the positions of various gratings. The strain transfer coefficients of the sensor are analyzed based on the experiments designed for this study. The error of the experimental results is ˜2 μɛ when the strain is at 60 μɛ and below. Moreover, the measured curves almost completely coincide with the theoretical curves. The changes in the internal strain field inside the embedded structure of the basalt fiber-encapsulated FBG strain sensor could be easily monitored. Hence, important references are provided to measure the internal stress strain of the sensor.

Optical filtering in directly modulated/detected OOFDM systems.

Science.gov (United States)

Sánchez, C; Ortega, B; Wei, J L; Capmany, J

2013-12-16

This work presents a theoretical investigation on the performance of directly modulated/detected (DM/DD) optical orthogonal frequency division multiplexed (OOFDM) systems subject to optical filtering. The impact of both linear and nonlinear distortion effects are taken into account to calculate the effective signal-to-noise ratio of each subcarrier. These results are then employed to optimize the design parameters of two simple optical filtering structures: a Mach Zehnder interferometer and a uniform fiber Bragg grating, leading to a significant optical power budget improvement given by 3.3 and 3dB, respectively. These can be further increased to 5.5 and 4.2dB respectively when balanced detection configurations are employed. We find as well that this improvement is highly dependent on the clipping ratio.

Advanced Methods for Direct Ink Write Additive Manufacturing

Energy Technology Data Exchange (ETDEWEB)

Compel, W. S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lewicki, J. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2018-01-24

Lawrence Livermore National Laboratory is one of the world’s premier labs for research and development of additive manufacturing processes. Out of these many processes, direct ink write (DIW) is arguably one of the most relevant for the manufacture of architected polymeric materials, components and hardware. However, a bottleneck in this pipeline that has largely been ignored to date is the lack of advanced software implementation with respect to toolpath execution. There remains to be a convenient, automated method to design and produce complex parts that is user-friendly and enabling for the realization of next generation designs and structures. For a material to be suitable as a DIW ink it must possess the appropriate rheological properties for this process. Most importantly, the material must exhibit shear-thinning in order to extrude through a print head and have a rapid recovery of its static shear modulus. This makes it possible for the extrudate to be self-supporting upon exiting the print head. While this and other prerequisites narrow the scope of ‘offthe- shelf’ printable materials directly amenable to DIW, the process still tolerates a wide range of potential feedstock materials. These include metallic alloys, inorganic solvent borne dispersions, polymeric melts, filler stabilized monomer compositions, pre-elastomeric feedstocks and thermoset resins each of which requires custom print conditions tailored to the individual ink. As such, an ink perfectly suited for DIW may be prematurely determined to be undesirable for the process if printed under the wrong conditions. Defining appropriate print conditions such as extrusion rate, layer height, and maximum bridge length is a vital first step in validating an ink’s DIW capability.

Spectroscopic enhancement in nanoparticles embedded glasses

Energy Technology Data Exchange (ETDEWEB)

Sahar, M. R., E-mail: mrahim057@gmail.com; Ghoshal, S. K., E-mail: mrahim057@gmail.com [Advanced Optical Material Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru, Johor (Malaysia)

2014-09-25

This presentation provides an overview of the recent progress in the enhancement of the spectroscopic characteristics of the glass embedded with nanoparticles (NPs). Some of our research activities with few significantly new results are highlighted and facilely analyzed. The science and technology dealing with the manipulation of the physical properties of rare earth doped inorganic glasses by embedding metallic NPs or nanoclusters produce the so-called 'nanoglass'. Meanwhile, the spectroscopic enhancement relates the intensity of the luminescence measured at certain transition. The enhancement which expectedly due to the 'plasmonics wave' (referring to the coherent coupling of photons to free electron oscillations called plasmon) occurs at the interface between a conductor and a dielectric. Plasmonics being an emerging concept in advanced optical material of nanophotonics has given this material the ability to exploit the optical response at nanoscale and opened up a new avenue in metal-based glass optics. There is a vast array of plasmonic NPs concepts yet to be explored, with applications spanning solar cells, (bio) sensing, communications, lasers, solid-state lighting, waveguides, imaging, optical data transfer, display and even bio-medicine. Localized surface plasmon resonance (LSPR) can enhance the optical response of nanoglass by orders of magnitude as observed. The luminescence enhancement and surface enhanced Raman scattering (SERS) are new paradigm of research. The enhancement of luminescence due to the influence of metallic NPs is the recurring theme of this paper.

Kindergarten Predictors of Third Grade Writing

Science.gov (United States)

Kim, Young-Suk; Al Otaiba, Stephanie; Wanzek, Jeanne

2015-01-01

The primary goal of the present study was to examine the relations of kindergarten transcription, oral language, word reading, and attention skills to writing skills in third grade. Children (N = 157) were assessed on their letter writing automaticity, spelling, oral language, word reading, and attention in kindergarten. Then, they were assessed on writing in third grade using three writing tasks – one narrative and two expository prompts. Children’s written compositions were evaluated in terms of writing quality (the extent to which ideas were developed and presented in an organized manner). Structural equation modeling showed that kindergarten oral language and lexical literacy skills (i.e., word reading and spelling) were independently predicted third grade narrative writing quality, and kindergarten literacy skill uniquely predicted third grade expository writing quality. In contrast, attention and letter writing automaticity were not directly related to writing quality in either narrative or expository genre. These results are discussed in light of theoretical and practical implications. PMID:25642118

Visually Imperceptible Liquid-Metal Circuits for Transparent, Stretchable Electronics with Direct Laser Writing.

Science.gov (United States)

Pan, Chengfeng; Kumar, Kitty; Li, Jianzhao; Markvicka, Eric J; Herman, Peter R; Majidi, Carmel

2018-03-01

A material architecture and laser-based microfabrication technique is introduced to produce electrically conductive films (sheet resistance = 2.95 Ω sq -1 ; resistivity = 1.77 × 10 -6 Ω m) that are soft, elastic (strain limit >100%), and optically transparent. The films are composed of a grid-like array of visually imperceptible liquid-metal (LM) lines on a clear elastomer. Unlike previous efforts in transparent LM circuitry, the current approach enables fully imperceptible electronics that have not only high optical transmittance (>85% at 550 nm) but are also invisible under typical lighting conditions and reading distances. This unique combination of properties is enabled with a laser writing technique that results in LM grid patterns with a line width and pitch as small as 4.5 and 100 µm, respectively-yielding grid-like wiring that has adequate conductivity for digital functionality but is also well below the threshold for visual perception. The electrical, mechanical, electromechanical, and optomechanical properties of the films are characterized and it is found that high conductivity and transparency are preserved at tensile strains of ≈100%. To demonstrate their effectiveness for emerging applications in transparent displays and sensing electronics, the material architecture is incorporated into a couple of illustrative use cases related to chemical hazard warning. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct writing of microtunnels using proton beam micromachining

International Nuclear Information System (INIS)

Marot, Laurent; Munnik, Frans; Mikhailov, Serguei

2006-01-01

The production of high aspect ratio microstructures is a potential growth area. The combination of deep X-ray lithography with electroforming and micromolding (i.e. LIGA) is one of the main techniques used to produce 3D microstructures. The new technique of proton micromachining employs focused MeV protons in a direct write process which is complementary to LIGA. During ion exposure of positive photoresist like PMMA, scission of molecular chains occurs. These degraded polymer chains are removed by the developer. The aim of this paper is to investigate the capabilities of proton micromachining as a lithographic technique. We show the realization of sub-surface channels, or microtunnels, which have been fabricated in only one exposure and without cutting or resurfacing the material. Using our Van-de-Graaff accelerator, the resist (PMMA) has been exposed with high-energy protons (2.5 MeV). The range of charged particles in matter is well-defined and depends on the energy. Therefore, it is possible to obtain a dose which is sufficient to develop the bottom part of the ion paths but not the top part. Thus, by selecting the energy and the exposure time, a big variety of microtunnels can be realized

Laser-Direct Writing of Silver Metal Electrodes on Transparent Flexible Substrates with High-Bonding Strength.

Science.gov (United States)

Zhou, Weiping; Bai, Shi; Ma, Ying; Ma, Delong; Hou, Tingxiu; Shi, Xiaomin; Hu, Anming

2016-09-21

We demonstrate a novel approach to rapidly fabricate conductive silver electrodes on transparent flexible substrates with high-bonding strength by laser-direct writing. A new type of silver ink composed of silver nitrate, sodium citrate, and polyvinylpyrrolidone (PVP) was prepared in this work. The role of PVP was elucidated for improving the quality of silver electrodes. Silver nanoparticles and sintered microstructures were simultaneously synthesized and patterned on a substrate using a focused 405 nm continuous wave laser. The writing was completed through the transparent flexible substrate with a programmed 2D scanning sample stage. Silver electrodes fabricated by this approach exhibit a remarkable bonding strength, which can withstand an adhesive tape test at least 50 times. After a 1500 time bending test, the resistance only increased 5.2%. With laser-induced in-situ synthesis, sintering, and simultaneous patterning of silver nanoparticles, this technology is promising for the facile fabrication of conducting electronic devices on flexible substrates.

Embedded Active Fiber Optic Sensing Network for Structural Health Monitoring in Harsh Environments

Energy Technology Data Exchange (ETDEWEB)

Wang, Anbo [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

2016-09-30

This report summarizes technical progress on the program “Embedded Active Fiber Optic Sensing Network for Structural Health Monitoring in Harsh Environments” funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Center for Photonics Technology at Virginia Tech. The objective of this project is to develop a first-of-a-kind technology for remote fiber optic generation and detection of acoustic waves for structural health monitoring in harsh environments. During the project period, which is from April 1, 2013 to Septemeber 30, 2016, three different acoustic generation mechanisms were studied in detail for their applications in building a fiber optic acoustic generation unit (AGU), including laser induced plasma breakdown (LIP), Erbium-doped fiber laser absorption, and metal laser absorption. By comparing the performance of the AGUs designed based on these three mechanisms and analyzing the experimental results with simulations, the metal laser absorption method was selected to build a complete fiber optic structure health monitoring (FO-SHM) system for the proposed high temperature multi-parameter structure health monitoring application. Based on the simulation of elastic wave propagation and fiber Bragg grating acoustic pulse detection, an FO-SHM element together with a completed interrogation system were designed and built. This system was first tested on an aluminum piece in the low-temperature range and successfully demonstrated its capability of multi-parameter monitoring and multi-point sensing. In the later stages of the project, the research was focused on improving the surface attachment design and preparing the FO-SHM element for high temperature environment tests. After several upgrades to the surface attachment methods, the FO-SHM element was able to work reliably up to 600oC when attached to P91 pipes, which are the target material of this project. In the final stage of this project, this FO

An optical Fourier transform coprocessor with direct phase determination.

Science.gov (United States)

Macfaden, Alexander J; Gordon, George S D; Wilkinson, Timothy D

2017-10-20

The Fourier transform is a ubiquitous mathematical operation which arises naturally in optics. We propose and demonstrate a practical method to optically evaluate a complex-to-complex discrete Fourier transform. By implementing the Fourier transform optically we can overcome the limiting O(nlogn) complexity of fast Fourier transform algorithms. Efficiently extracting the phase from the well-known optical Fourier transform is challenging. By appropriately decomposing the input and exploiting symmetries of the Fourier transform we are able to determine the phase directly from straightforward intensity measurements, creating an optical Fourier transform with O(n) apparent complexity. Performing larger optical Fourier transforms requires higher resolution spatial light modulators, but the execution time remains unchanged. This method could unlock the potential of the optical Fourier transform to permit 2D complex-to-complex discrete Fourier transforms with a performance that is currently untenable, with applications across information processing and computational physics.

Simulation flow and model verification for laser direct-write lithography

Science.gov (United States)

Onanuga, Temitope; Rumler, Maximilian; Erdmann, Andreas

2017-07-01

A simulation flow for laser direct-write lithography (LDWL), a maskless lithography process in which a focused laser beam is scanned through a photoresist, is proposed. The simulation flow includes focusing of Gaussian beams, photoresist exposure, free-radical polymerization chemistry of the photoresist, and photoresist development. We applied the simulation method to investigate the scaling of feature sizes or linewidths for a varying number of exposure cycles at a total constant exposure dose. Experimental results from literature demonstrate that exposing the photoresist over multiple exposure cycles causes a reduction in linewidths. We explore possible reasons for this phenomenon and conclude that radical losses occurring between subsequent exposures provide a possible explanation of the observed effects. Furthermore, we apply the developed simulation method to analyze lithographic structures that were fabricated by a combination of LDWL and nanoimprint lithography. The simulation results agree with the experimental tendencies of a reduced likelihood of overexposures with an increase in the number of exposure cycles.

Jet behaviors and ejection mode recognition of electrohydrodynamic direct-write

Science.gov (United States)

Zheng, Jianyi; Zhang, Kai; Jiang, Jiaxin; Wang, Xiang; Li, Wenwang; Liu, Yifang; Liu, Juan; Zheng, Gaofeng

2018-01-01

By introducing image recognition and micro-current testing, jet behavior research was conducted, in which the real-time recognition of ejection mode was realized. To study the factors influencing ejection modes and the current variation trends under different modes, an Electrohydrodynamic Direct-Write (EDW) system with functions of current detection and ejection mode recognition was firstly built. Then a program was developed to recognize the jet modes. As the voltage applied to the metal tip increased, four jet ejection modes in EDW occurred: droplet ejection mode, Taylor cone ejection mode, retractive ejection mode and forked ejection mode. In this work, the corresponding relationship between the ejection modes and the effect on fiber deposition as well as current was studied. The real-time identification of ejection mode and detection of electrospinning current was realized. The results in this paper are contributed to enhancing the ejection stability, providing a good technical basis to produce continuous uniform nanofibers controllably.

Carbon/ternary alloy/carbon optical stack on mylar as an optical data storage medium to potentially replace magnetic tape.

Science.gov (United States)

Wang, Hao; Lunt, Barry M; Gates, Richard J; Asplund, Matthew C; Shutthanandan, V; Davis, Robert C; Linford, Matthew R

2013-09-11

A novel write-once-read-many (WORM) optical stack on Mylar tape is proposed as a replacement for magnetic tape for archival data storage. This optical tape contains a cosputtered bismuth-tellurium-selenium (BTS) alloy as the write layer sandwiched between thin, protective films of reactively sputtered carbon. The composition and thickness of the BTS layer were confirmed by Rutherford Backscattering (RBS) and atomic force microscopy (AFM), respectively. The C/BTS/C stack on Mylar was written to/marked by 532 nm laser pulses. Under the same conditions, control Mylar films without the optical stack were unaffected. Marks, which showed craters/movement of the write material, were characterized by optical microscopy and AFM. The threshold laser powers for making marks on C/BTS/C stacks with different thicknesses were explored. Higher quality marks were made with a 60× objective compared to a 40× objective in our marking apparatus. The laser writing process was simulated with COMSOL.

Carbon/Ternary Alloy/Carbon Optical Stack on Mylar as an Optical Data Storage Medium to Potentially Replace Magnetic Tape

Energy Technology Data Exchange (ETDEWEB)

Wang, Hao; Lunt, Barry M.; Gates, Richard J.; Asplund, Matthew C.; Shutthanandan, V.; Davis, Robert C.; Linford, Matthew R.

2013-09-11

A novel write-once-read-many (WORM) optical stack on Mylar tape is proposed as a replacement for magnetic tape for archival data storage. This optical tape contains a cosputtered bismuth–tellurium–selenium (BTS) alloy as the write layer sandwiched between thin, protective films of reactively sputtered carbon. The composition and thickness of the BTS layer were confirmed by Rutherford Backscattering (RBS) and atomic force microscopy (AFM), respectively. The C/BTS/C stack on Mylar was written to/marked by 532 nm laser pulses. Under the same conditions, control Mylar films without the optical stack were unaffected. Marks, which showed craters/movement of the write material, were characterized by optical microscopy and AFM. The threshold laser powers for making marks on C/BTS/C stacks with different thicknesses were explored. Higher quality marks were made with a 60× objective compared to a 40× objective in our marking apparatus. Finally, the laser writing process was simulated with COMSOL.

Optical CDMA with Embedded Spectral-Polarization Coding over Double Balanced Differential-Detector

Science.gov (United States)

Huang, Jen-Fa; Yen, Chih-Ta; Chen, Bo-Hau

A spectral-polarization coding (SPC) optical code-division multiple-access (OCDMA) configuration structured over arrayed-waveguide grating (AWG) router is proposed. The polarization-division double balanced detector is adopted to execute difference detection and enhances system performance. The signal-to-noise ratio (SNR) is derived by taking the effect of PIIN into account. The result indicates that there would be up to 9-dB SNR improvement than the conventional spectral-amplitude coding (SAC) structures with Walsh-Hadamard codes. Mathematical deriving results of the SNR demonstrate the system embedded with the orthogonal state of polarization (SOP) will suppress effectively phase-induced intensity noise (PIIN). In addition, we will analyze the relations about bit error rate (BER) vs. the number of active users under the different encoding schemes and compare them with our proposed scheme. The BER vs. the effective power under the different encoding scheme with the same number of simultaneous active user conditions are also revealed. Finally, the polarization-matched factor and the difference between simulated and experimental values are discussed.

Electrochemical writing on edible polysaccharide films for intelligent food packaging.

Science.gov (United States)

Wu, Si; Wang, Wenqi; Yan, Kun; Ding, Fuyuan; Shi, Xiaowen; Deng, Hongbing; Du, Yumin

2018-04-15

Polysaccharide films used as intelligent food packaging possess the advantages of renewability, safety and biodegradability. Printing on the polysaccharidic food packaging is challenging due to the high demand for edible-ink and the need for a suitable printing technique. In this work, we propose an electrochemical method for writing on polysaccharide film. Unlike conventional printing, this electrochemical writing process relies on the pH responsive color change of anthocyanin embedded in the chitosan/agarose hydrogel. By biasing a negative potential to a stainless wire (used as a pen) contacting the surface of the chitosan/agarose/ATH hydrogel, the locally generated pH change induced the color change of ATH and wrote programmed information on the hydrogel. We demonstrate the writing can be temporary in the hydrogel but stable when the hydrogel is dried. We further demonstrate that the written film is applicable for the detection of the spoilage of crucian fish. The reported electrochemical writing process provides a novel method for printing information on polysaccharide film and great potential for intelligent food packaging. Copyright © 2018 Elsevier Ltd. All rights reserved.

Direct electro-optic effect in langasites and α-quartz

Science.gov (United States)

Ivanov, Vadim

2018-05-01

Strain-constant (clamped) electro-optic coefficients r11S of langasite La3Ga5SiO14 (LGS), langatate La3Ga5.5Ta0.5O14 (LGT), catangasite Ca3TaGa3Si2O14 (CTGS) and α-quartz are measured at 1540 nm in the frequency range of 3-25 MHz. Experimental ratio of clamped and unclamped electro-optic coefficients r11S/r11T is 0.97 for LGS, 0.91 for LGT, 0.31 for CTGS, and 0.49 for quartz. Most of direct electro-optic effect in LGS and LGT is associated with lanthanum ions: clamped electro-optic coefficient r11S in lanthanum-free CTGS is 14 times less than in LGS. Low piezoelectric contribution to unclamped electro-optic coefficient r11T makes LGS and LGT promising materials for electro-optic devices, whose performance can be deteriorated by piezoelectric effect, especially, for high-voltage optical voltage sensors.

Quantum-dot based nanothermometry in optical plasmonic recording media

International Nuclear Information System (INIS)

Maestro, Laura Martinez; Zhang, Qiming; Li, Xiangping; Gu, Min; Jaque, Daniel

2014-01-01

We report on the direct experimental determination of the temperature increment caused by laser irradiation in a optical recording media constituted by a polymeric film in which gold nanorods have been incorporated. The incorporation of CdSe quantum dots in the recording media allowed for single beam thermal reading of the on-focus temperature from a simple analysis of the two-photon excited fluorescence of quantum dots. Experimental results have been compared with numerical simulations revealing an excellent agreement and opening a promising avenue for further understanding and optimization of optical writing processes and media

Clad modified optical fiber gas sensors based on nanocrystalline nickel oxide embedded coatings

Science.gov (United States)

Yamini, K.; Renganathan, B.; Ganesan, A. R.; Prakash, T.

2017-07-01

A clad modified optical fiber gas sensor for sensing volatile organic compound vapours (VOCs) such as formaldehyde (HCHO), ammonia (NH3), ethanol (C2H5OH) and methanol (CH3OH) up to 500 ppm was studied using nanocrystalline nickel oxide embedded coatings. Prior to the measurements, nickel oxide in two different crystallite sizes such as 24 nm and 76 nm was synthesized by calcination of reverse precipitated nickel hydroxide subsequently at 450 °C and 900 °C for 30 min. Then, samples physical properties were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Our gas sensing measurement concludes that the lower crystallite size (24 nm) nickel oxide nanocrystals exhibits superior performance to formaldehyde and ethanol vapours as compared with other two VOCs, the observed experimental results were discussed in detail.

Detection of local birefringence in embedded fiber Bragg grating caused by concentrated transverse load using optical frequency domain reflectometry

Science.gov (United States)

Wada, D.; Murayama, H.; Igawa, H.

2014-05-01

We investigate the capability of local birefringence detection in an embedded fiber Bragg grating (FBG) using optical frequency domain reflectometry. We embed an FBG into carbon fiber reinforced plastic specimen, and conduct 3-point bending test. The cross-sectional stresses are applied to the FBG at the loading location in addition to the non-uniform longitudinal strain distribution over the length of the FBG. The local birefringence due to the cross-sectional stresses was successfully detected while the non-uniform longitudinal strain distribution was accurately measured.

Embedded high-contrast distributed grating structures

Science.gov (United States)

Zubrzycki, Walter J.; Vawter, Gregory A.; Allerman, Andrew A.

2002-01-01

A new class of fabrication methods for embedded distributed grating structures is claimed, together with optical devices which include such structures. These new methods are the only known approach to making defect-free high-dielectric contrast grating structures, which are smaller and more efficient than are conventional grating structures.

Direct implantation versus platelet-rich fibrin-embedded adipose-derived mesenchymal stem cells in treating rat acute myocardial infarction.

Science.gov (United States)

Sun, Cheuk-Kwan; Zhen, Yen-Yi; Leu, Steve; Tsai, Tzu-Hsien; Chang, Li-Teh; Sheu, Jiunn-Jye; Chen, Yung-Lung; Chua, Sarah; Chai, Han-Tan; Lu, Hung-I; Chang, Hsueh-Wen; Lee, Fan-Yen; Yip, Hon-Kan

2014-05-15

This study tested whether adipose-derived mesenchymal stem cells (ADMSC) embedded in platelet-rich fibrin (PRF) scaffold is superior to direct ADMSC implantation in improving left ventricular (LV) performance and reducing LV remodeling in a rat acute myocardial infarction (AMI) model of left anterior descending coronary artery (LAD) ligation. Twenty-eight male adult Sprague Dawley rats equally divided into group 1 [sham control], group 2 (AMI only), group 3 (AMI+direct ADMSC implantation), and group 4 (AMI+PRF-embedded autologous ADMSC) were sacrificed on day 42 after AMI. LV systolic and diastolic dimensions and volumes, and infarct/fibrotic areas were highest in group 2, lowest in group 1 and significantly higher in group 3 than in group 4, whereas LV performance and LV fractional shortening exhibited a reversed pattern (p<0.005). Protein expressions of inflammation (oxidative stress, IL-1β, MMP-9), apoptosis (mitochondrial Bax, cleaved PARP), fibrosis (Smad3, TGF-β), and pressure-overload biomarkers (BNP, MHC-β) displayed a pattern similar to that of LV dimensions, whereas anti-inflammatory (IL-10), anti-apoptotic (Bcl-2), and anti-fibrotic (Smad1/5, BMP-2) indices showed a pattern similar to that of LV performance among the four groups (all p<0.05). Angiogenesis biomarkers at protein (CXCR4, SDF-1α, VEGF), cellular (CD31+, CXCR4+, SDF-1α+), and immunohistochemical (small vessels) levels, and cardiac stem cell markers (C-kit+, Sca-1+) in infarct myocardium were highest in group 4, lowest in group 1, and significantly higher in group 3 than in group 2 (all p<0.005). PRF-embedded ADMSC is superior to direct ADMSC implantation in preserving LV function and attenuating LV remodeling. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Generating size-controlled embryoid bodies using laser direct-write

International Nuclear Information System (INIS)

Dias, A D; Corr, D T; Unser, A M; Xie, Y; Chrisey, D B

2014-01-01

Embryonic stem cells (ESCs) have the potential to self-renew and differentiate into any specialized cell type. One common method to differentiate ESCs in vitro is through embryoid bodies (EBs), three-dimensional cellular aggregates that spontaneously self-assemble and generally express markers for the three germ layers, endoderm, ectoderm, and mesoderm. It has been previously shown that both EB size and 2D colony size each influence differentiation. We hypothesized that we could control the size of the EB formed by mouse ESCs (mESCs) by using a cell printing method, laser direct-write (LDW), to control both the size of the initial printed colony and the local cell density in printed colonies. After printing mESCs at various printed colony sizes and printing densities, two-way ANOVAs indicated that the EB diameter was influenced by printing density after three days (p = 0.0002), while there was no effect of the printed colony diameter on the EB diameter at the same timepoint (p = 0.74). There was no significant interaction between these two factors. Tukey's honestly significant difference test showed that high-density colonies formed significantly larger EBs, suggesting that printed mESCs quickly aggregate with nearby cells. Thus, EBs can be engineered to a desired size by controlling printing density, which will influence the design of future differentiation studies. Herein, we highlight the capacity of LDW to control the local cell density and colony size independently, at prescribed spatial locations, potentially leading to better stem cell maintenance and directed differentiation. (paper)

Direct cell writing of 3D microorgan for in vitro pharmacokinetic model.

Science.gov (United States)

Chang, Robert; Nam, Jae; Sun, Wei

2008-06-01

A novel targeted application of tissue engineering is the development of an in vitro pharmacokinetic model for drug screening and toxicology. An in vitro pharmacokinetic model is needed to realistically and reliably predict in vivo human response to drug administrations and potential toxic exposures. This paper details the fabrication process development and adaptation of microfluidic devices for the creation of such a physiologically relevant pharmacokinetic model. First, an automated syringe-based, layered direct cell writing (DCW) bioprinting process creates a 3D microorgan that biomimics the cell's natural microenvironment with enhanced functionality. Next, soft lithographic micropatterning techniques are used to fabricate a microscale in vitro device to house the 3D microorgan. This paper demonstrates the feasibility of the DCW process for freeform biofabrication of 3D cell-encapsulated hydrogel-based tissue constructs with defined reproducible patterns, direct integration of 3D constructs onto a microfluidic device for continuous perfusion drug flow, and characterization of 3D tissue constructs with predictable cell viability/proliferation outcomes and enhanced functionality over traditional culture methods.

Phase-controlled localization and directed transport in an optical bipartite lattice.

Science.gov (United States)

Hai, Kuo; Luo, Yunrong; Lu, Gengbiao; Hai, Wenhua

2014-02-24

We investigate coherent control of a single atom interacting with an optical bipartite lattice via a combined high-frequency modulation. Our analytical results show that the quantum tunneling and dynamical localization can depend on phase difference between the modulation components, which leads to a different route for the coherent destruction of tunneling and a convenient phase-control method for stabilizing the system to implement the directed transport of atom. The similar directed transport and the phase-controlled quantum transition are revealed for the corresponding many-particle system. The results can be referable for experimentally manipulating quantum transport and transition of cold atoms in the tilted and shaken optical bipartite lattice or of analogical optical two-mode quantum beam splitter, and also can be extended to other optical and solid-state systems.

The Effects of Teacher Directed Writing Instruction Combined with SOLO Literacy Suite

Science.gov (United States)

Park, Y.; Ambrose, G.; Coleman, M. B.; Moore, T. C.

2017-01-01

The purpose of this study was to examine the effectiveness of an intervention in which teacher-led instruction was combined with computerized writing software to improve paragraph writing for three middle school students with intellectual disability. A multiple probe across participants design was used to evaluate the effectiveness of the…

Balancing Self-Directed Learning with Expert Mentoring: The Science Writing Heuristic Approach

Science.gov (United States)

Shelley, Mack; Fostvedt, Luke; Gonwa-Reeves, Christopher; Baenziger, Joan; McGill, Michael; Seefeld, Ashley; Hand, Brian; Therrien, William; Taylor, Jonte; Villanueva, Mary Grace

2012-01-01

This study focuses on the implementation of the Science Writing Heuristic (SWH) curriculum (Hand, 2007), which combines current understandings of learning as a cognitive and negotiated process with the techniques of argument-based inquiry, critical thinking skills, and writing to strengthen student outcomes. Success of SWH is dependent on the…

All-optical switching using a new photonic crystal directional coupler

Directory of Open Access Journals (Sweden)

B. Vakili

2015-07-01

Full Text Available In this paper all-optical switching in a new photonic crystal directional coupler is performed.  The structure of the switch consists of a directional coupler and a separate path for a control signal called “control waveguide”. In contrast to the former reported structures in which the directional couplers are made by removing a row of rods entirely, the directional coupler in our optical switch is constructed by two reduced-radius line-defect waveguides separated by the control waveguide. Furthermore, in our case the background material has the nonlinear Kerr property. Therefore, in the structure of this work, no frequency overlap occurs between the control waveguide mode and the directional coupler modes. It is shown that such a condition provides a very good isolation between the control and the probe signals at the output ports. In the control waveguide, nonlinear Kerr effect causes the required refractive index change by the presence of a high power control (pump signal. Even and odd modes of the coupler are investigated by applying the distribution of the refractive index change in the nonlinear region of a super-cell so that a switching length of about 94 µm is obtained at the wavelength of 1.55 µm. Finally, all-optical switching of the 1.55 µm probe signal using a control signal at the wavelength of 1.3 µm, is simulated through the finite-difference time-domain method, where both signals are desirable in optical communication systems. A very high extinction ratio of 67 dB is achieved and the temporal characteristics of the switch are demonstrated.

Further Thoughts on "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games"

Science.gov (United States)

Oliveri, María Elena; Khan, Saad

2014-01-01

María Oliveri, and Saad Khan write that the article: "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games" provided helpful illustrations regarding the implementation of evidence-centered assessment design (Mislevy & Haertel, 2006; Mislevy, Steinberg, & Almond, 1999) with games and simulations.…

The Design of Polymer Planar Optical Triplexer with MMI Filter and Directional Coupler

Directory of Open Access Journals (Sweden)

V. Jerabek

2013-12-01

Full Text Available Optical bidirectional WDM transceiver is a key component of the Passive Optical Network of the Fiber to the Home topology. Essential parts of such transceivers are filters that combine multiplexing and demultiplexing function of optical signal (triplexing filters. In this paper we report about a design of a new planar optical multi-wavelength selective system triplexing filter, which combines a multimode interference filter with directional coupler based on the epoxy polymer SU-8 on Si/SiO2 substrate. The optical triplexing filter was designed using the Beam Propagation Method. The aim of this project was to optimize the triplexing filter optical parameters and to minimize the planar optical wavelength selective system dimensions. The multimode interference filter was used for separation of downstream optical signal in designed optoelectronic integrated WDM transceiver. The directional coupler was used for adding of upstream optical signal.

Phylogenetic trees and Euclidean embeddings.

Science.gov (United States)

Layer, Mark; Rhodes, John A

2017-01-01

It was recently observed by de Vienne et al. (Syst Biol 60(6):826-832, 2011) that a simple square root transformation of distances between taxa on a phylogenetic tree allowed for an embedding of the taxa into Euclidean space. While the justification for this was based on a diffusion model of continuous character evolution along the tree, here we give a direct and elementary explanation for it that provides substantial additional insight. We use this embedding to reinterpret the differences between the NJ and BIONJ tree building algorithms, providing one illustration of how this embedding reflects tree structures in data.

Natural Fe{sub 3}O{sub 4} nanoparticles embedded zinc–tellurite glasses: Polarizability and optical properties

Energy Technology Data Exchange (ETDEWEB)

Widanarto, W. [Physics Study Program, Jenderal Soedirman University, Jl. Dr. Soeparno 61, Purwokerto 53123 (Indonesia); Sahar, M.R., E-mail: rahimsahar@utm.my [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia); Ghoshal, S.K.; Arifin, R.; Rohani, M.S.; Hamzah, K. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia); Jandra, M. [FTI, University Teknologi Malaysia, Johor Bahru, Skudai 81310 (Malaysia)

2013-02-15

Modifying the optical behavior of zinc–tellurite glass by embedding magnetic nanoparticles has implication in nanophotonics. A series of zinc–tellurite glasses containing natural Fe{sub 3}O{sub 4} nanoparticles with composition (80 − x)TeO{sub 2}·xFe{sub 3}O{sub 4}·20ZnO (0 ≤ x ≤ 2) in mol% are synthesized by melt quenching method and their optical properties are investigated using FTIR and UV–vis–NIR spectroscopies. Lorentz–Lorenz relations are exploited to determine the refractive index, molar refraction and electronic polarizability. The sharp absorption peaks of FTIR spectra show a shift from 667 cm{sup −1} to 671 cm{sup −1} in the presence of nanoparticles that increase the non-bridging oxygen, confirmed by the intensity change of the TeO{sub 3} peak at 752 cm{sup −1}. A new peak around 461 cm{sup −1} is also observed which is attributed to the band characteristic of covalent Fe–O linkages. A decrease in the Urbach energy as much as 0.122 eV and the optical energy band gap with the increase of Fe{sub 3}O{sub 4} concentration (0.5–1.0 mol%) is evidenced. Electronic polarizability of the glasses increases with increasing Fe{sub 3}O{sub 4} nanoparticles concentration up to 1 mol%. Interestingly, the polarizability tends to decrease with the further increase of Fe{sub 3}O{sub 4} concentration at 2 mol%. The role of magnetic nanoparticles in influencing the structural and optical behavior are examined and understood. - Highlights: ► Incorporation of natural Fe{sub 3}O{sub 4} nanoparticles into the zinc–tellurite glass. ► Influence of magnetic nanoparticles in modifying structure and optical properties. ► Enhancement of refraction index and change in electronic polarizability.

Fluorescent scattering by molecules embedded in small particles. Progress report, May 1, 1977--October 31, 1978

International Nuclear Information System (INIS)

Chew, H.; McNulty, P.J.

1978-01-01

A model for the fluorescence and Raman scattering by molecules that comprise or are embedded in small particles was developed and numerical calculations performed. The emphasis during this first year of the contract was on writing and testing the computer programs necessary for numerical calculations and on demonstrating the extent of the potential effects that the geometrical and optical properties of the particle would have on the Raman and fluorescent emissions. For the purpose of demonstrating effects emphasis was focused upon the case of isotropically polarizable molecules that fluoresce or Raman scatter through electric dipole transitions. Some preliminary results are described. One result of these investigations that is of particular significance for remote sensing of pollutants is that it would be a serious mistake to use inelastic scattering techniques such as Raman and fluorescent scattering for quantitative assay of specific molecules in aerosols containing particulates without taking into account the size, structure and refractive index of the particles. A list of publications is included

Laser Direct Write micro-fabrication of large area electronics on flexible substrates

International Nuclear Information System (INIS)

Zacharatos, F.; Makrygianni, M.; Geremia, R.; Biver, E.; Karnakis, D.; Leyder, S.; Puerto, D.; Delaporte, P.; Zergioti, I.

2016-01-01

Highlights: • Laser Direct Writing of metallic patterns with a minimum feature size of 1 μm. • Selective Laser Ablation of 50 nm thick metal films on flexible substrates. • Selective Laser sintering resulting in an electrical resistivity of 9 μΩ cm. • Laser fabrication of interdigitated electrodes for sensor applications. - Abstract: To date, Laser Direct Write (LDW) techniques, such as Laser Induced Forward Transfer (LIFT), selective laser ablation and selective laser sintering of metal nanoparticle (NP) ink layers are receiving growing attention for the printing of uniform and well-defined conductive patterns with resolution down to 10 μm. For flexible substrates in particular, selective laser sintering of such NP patterns has been widely applied, as a low temperature and high resolution process compatible with large area electronics. In this work, LDW of silver NP inks has been carried out on polyethylene-terephthalate (PET), polyethylene-naphthalate (PEN) and polyimide (PI) substrates to achieve low electrical resistivity electrodes. In more detail, high speed short pulsed (picosecond and nanosecond) lasers with repetition rates up to 1 MHz were used to print (LIFT) metal NP inks. We thus achieved uniform and continuous patterns with a minimum feature size of 1 μm and a total footprint larger than 1 cm"2. Next, the printed patterns were laser sintered with ns pulses at 532 nm over a wide laser fluence window, resulting in an electrical resistivity of 10 μΩ cm. We carried out spatial beam shaping experiments to achieve a top-hat laser intensity profile and employed selective laser ablation of thin films (thickness on the order of 100 nm) to produce silver micro-electrodes with a resolution on the order of 10 μm and a low line edge roughness. Laser sintering was combined with laser ablation to constitute a fully autonomous micro-patterning technique of metallic micro-features, with a 10 μm resolution and geometrical characteristics tuned for

Laser Direct Write micro-fabrication of large area electronics on flexible substrates

Energy Technology Data Exchange (ETDEWEB)

Zacharatos, F.; Makrygianni, M. [National Technical University of Athens, Physics Department, Zografou Campus, 15780 (Greece); Geremia, R.; Biver, E.; Karnakis, D. [Oxford Lasers Ltd, Unit 8 Moorbrook Park, Oxfordshire OX11 7HP (United Kingdom); Leyder, S.; Puerto, D.; Delaporte, P. [Aix-Marseille University, CNRS, LP3 – UMR 7341, 13288 Marseille Cedex 9 (France); Zergioti, I., E-mail: zergioti@central.ntua.gr [National Technical University of Athens, Physics Department, Zografou Campus, 15780 (Greece)

2016-06-30

Highlights: • Laser Direct Writing of metallic patterns with a minimum feature size of 1 μm. • Selective Laser Ablation of 50 nm thick metal films on flexible substrates. • Selective Laser sintering resulting in an electrical resistivity of 9 μΩ cm. • Laser fabrication of interdigitated electrodes for sensor applications. - Abstract: To date, Laser Direct Write (LDW) techniques, such as Laser Induced Forward Transfer (LIFT), selective laser ablation and selective laser sintering of metal nanoparticle (NP) ink layers are receiving growing attention for the printing of uniform and well-defined conductive patterns with resolution down to 10 μm. For flexible substrates in particular, selective laser sintering of such NP patterns has been widely applied, as a low temperature and high resolution process compatible with large area electronics. In this work, LDW of silver NP inks has been carried out on polyethylene-terephthalate (PET), polyethylene-naphthalate (PEN) and polyimide (PI) substrates to achieve low electrical resistivity electrodes. In more detail, high speed short pulsed (picosecond and nanosecond) lasers with repetition rates up to 1 MHz were used to print (LIFT) metal NP inks. We thus achieved uniform and continuous patterns with a minimum feature size of 1 μm and a total footprint larger than 1 cm{sup 2}. Next, the printed patterns were laser sintered with ns pulses at 532 nm over a wide laser fluence window, resulting in an electrical resistivity of 10 μΩ cm. We carried out spatial beam shaping experiments to achieve a top-hat laser intensity profile and employed selective laser ablation of thin films (thickness on the order of 100 nm) to produce silver micro-electrodes with a resolution on the order of 10 μm and a low line edge roughness. Laser sintering was combined with laser ablation to constitute a fully autonomous micro-patterning technique of metallic micro-features, with a 10 μm resolution and geometrical characteristics tuned for

Optical characterization of directly deposited graphene on a dielectric substrate

DEFF Research Database (Denmark)

Kaplas, Tommi; Karvonen, Lasse; Ahmadi, Sepehr

2016-01-01

By using scanning multiphoton microscopy we compare the nonlinear optical properties of the directly deposited and transferred to the dielectric substrate graphene. The direct deposition of graphene on oxidized silicon wafer was done by utilizing sacrificial copper catalyst film. We demonstrate...

Controlling plasma distributions as driving forces for ion migration during fs laser writing

International Nuclear Information System (INIS)

Fernandez, Toney Teddy; Siegel, Jan; Hoyo, Jesus; Solis, Javier; Sotillo, Belen; Fernandez, Paloma

2015-01-01

The properties of structures written inside dielectrics with high repetition rate femtosecond lasers are known to depend strongly on the complex interplay of a large number of writing parameters. Recently, ion migration within the laser-excited volume has been identified as a powerful mechanism for changing the local element distribution and producing efficient optical waveguides. In this work it is shown that the transient plasma distribution induced during laser irradiation is a reliable monitor for predicting the final refractive index distribution of the waveguide caused by ion migration. By performing in situ plasma emission microscopy during the writing process inside a La-phosphate glass it is found that the long axis of the plasma distribution determines the axis of ion migration, being responsible for the local refractive index increase. This observation is also valid when strong positive or negative spherical aberration is induced, greatly deforming the focal volume and inverting the index profile. Even subtle changes in the writing conditions, such as an inversion of the writing direction (quill writing effect), show up in the form of a modified plasma distribution, which manifests as a modified index distribution. Finally, it is shown that the superior control over the waveguide properties employing the slit shaping technique is caused by the more confined plasma distribution produced. The underlying reasons for this unexpected result are discussed in terms of non-linear propagation and heat accumulation. (paper)

Controlling plasma distributions as driving forces for ion migration during fs laser writing

Science.gov (United States)

Teddy Fernandez, Toney; Siegel, Jan; Hoyo, Jesus; Sotillo, Belen; Fernandez, Paloma; Solis, Javier

2015-04-01

The properties of structures written inside dielectrics with high repetition rate femtosecond lasers are known to depend strongly on the complex interplay of a large number of writing parameters. Recently, ion migration within the laser-excited volume has been identified as a powerful mechanism for changing the local element distribution and producing efficient optical waveguides. In this work it is shown that the transient plasma distribution induced during laser irradiation is a reliable monitor for predicting the final refractive index distribution of the waveguide caused by ion migration. By performing in situ plasma emission microscopy during the writing process inside a La-phosphate glass it is found that the long axis of the plasma distribution determines the axis of ion migration, being responsible for the local refractive index increase. This observation is also valid when strong positive or negative spherical aberration is induced, greatly deforming the focal volume and inverting the index profile. Even subtle changes in the writing conditions, such as an inversion of the writing direction (quill writing effect), show up in the form of a modified plasma distribution, which manifests as a modified index distribution. Finally, it is shown that the superior control over the waveguide properties employing the slit shaping technique is caused by the more confined plasma distribution produced. The underlying reasons for this unexpected result are discussed in terms of non-linear propagation and heat accumulation.

Unsteady Flame Embedding

KAUST Repository

El-Asrag, Hossam A.

2011-01-01

Direct simulation of all the length and time scales relevant to practical combustion processes is computationally prohibitive. When combustion processes are driven by reaction and transport phenomena occurring at the unresolved scales of a numerical simulation, one must introduce a dynamic subgrid model that accounts for the multiscale nature of the problem using information available on a resolvable grid. Here, we discuss a model that captures unsteady flow-flame interactions- including extinction, re-ignition, and history effects-via embedded simulations at the subgrid level. The model efficiently accounts for subgrid flame structure and incorporates detailed chemistry and transport, allowing more accurate prediction of the stretch effect and the heat release. In this chapter we first review the work done in the past thirty years to develop the flame embedding concept. Next we present a formulation for the same concept that is compatible with Large Eddy Simulation in the flamelet regimes. The unsteady flame embedding approach (UFE) treats the flame as an ensemble of locally one-dimensional flames, similar to the flamelet approach. However, a set of elemental one-dimensional flames is used to describe the turbulent flame structure directly at the subgrid level. The calculations employ a one-dimensional unsteady flame model that incorporates unsteady strain rate, curvature, and mixture boundary conditions imposed by the resolved scales. The model is used for closure of the subgrid terms in the context of large eddy simulation. Direct numerical simulation (DNS) data from a flame-vortex interaction problem is used for comparison. © Springer Science+Business Media B.V. 2011.

Hardware Support for Embedded Java

DEFF Research Database (Denmark)

Schoeberl, Martin

2012-01-01

The general Java runtime environment is resource hungry and unfriendly for real-time systems. To reduce the resource consumption of Java in embedded systems, direct hardware support of the language is a valuable option. Furthermore, an implementation of the Java virtual machine in hardware enables...... worst-case execution time analysis of Java programs. This chapter gives an overview of current approaches to hardware support for embedded and real-time Java....

Costs and benefits of embedded generation

International Nuclear Information System (INIS)

1996-01-01

Ilex Associates has been appointed by ETSU to examine the underlying costs and benefits of embedded generation (i.e. generation which is directly connected into a REF's distribution network instead of the national transmission network). The main impetus for this work stems from the need to understand the true value of embedded generation in time to review the development of further NFFO contracts following the expiry of the, so called, ''nuclear levy''. This is particularly important at this time because of the view expressed by the Director General of Electricity Supply (DGES) that to continue to receive support renewables technologies should be able to demonstrate good progress in converging towards a market price. The prime objectives of this study are to determine the costs and benefits of connecting and operating a generator that is embedded in a local Regional Electricity Company's (REC's) distribution network compared to the alternative option of providing electricity from a large generating station which is connected directly to the transmission system (and colloquially known as directly connected generation). (UK)

Direct writing on graphene ‘paper’ by manipulating electrons as ‘invisible ink’

DEFF Research Database (Denmark)

Zhang, Wei; Zhang, Qiang; Zhao, Meng-Qiang

2013-01-01

The combination of self-assembly (bottom up) and nano-imprint lithography (top down) is an efficient and effective way to record information at the nanoscale by writing. The use of an electron beam for writing is quite a promising strategy; however, the ‘paper’ on which to save the information...... is not yet fully realized. Herein, graphene was selected as the thinnest paper for recording information at the nanoscale. In a transmission electron microscope, in situ high precision writing and drawing were achieved on graphene nanosheets by manipulating electrons with a 1 nm probe (probe current ∼2 × 10...... region. Therefore, the electron probe in STEM mode serves as invisible ink for nanoscale writing and drawing. These results not only shed new light on the application of graphene by the interaction of different forms of carbon, but also illuminate the interaction of different carbon forms through...

Factors influencing pre-service physics teachers' skills of writing teaching materials

Science.gov (United States)

Sinaga, Parlindungan

2016-02-01

Writing teaching materials is one of the generic pedagogical skills. Teachers and pre-service teachers should be trained to have the skills of writing teaching materials. This study examines the factors that influence the skills of writing in the disciplines among pre-service physics teachers. This study in particular aims to contribute to the development of science writing in the disciplines and to the organization of workshops on writing teaching materials for pre-service teachers. The problems of this research are formulated in the question of what are the factors that influence the skills of pre-service physics teachers in writing teaching materials. The research adopted mixed methods with embedded experimental design. The research subjects were 18 students enrolled in the school physics course. The instruments used consisted of conceptual understanding tests, learning strategy questionnaire, tests of the multiple representation skills, and one-on-one semi- structured interview. Results of data analysis show that the ability and skills of writing physics teaching materials of the pre- service physics teachers are determined by the factors of conceptual understanding of the subject matter with a contribution of 20%, the skills of making multiple representations of concepts with a contribution of 9.8% and students' self-regulation and learning strategy with a contribution of 33.5%. There are other factors that have not been investigated in this study; therefore, it is recommended that future research conduct further investigation on other factors that influence pre-service teachers' skills in writing physics teaching materials.

Direct writing of micro/nano-scale patterns by means of particle lens arrays scanned by a focused diode pumped Nd:YVO4 laser

Science.gov (United States)

Pena, Ana; Wang, Zengbo; Whitehead, David; Li, Lin

2010-11-01

A practical approach to a well-known technique of laser micro/nano-patterning by optical near fields is presented. It is based on surface patterning by scanning a Gaussian laser beam through a self-assembled monolayer of silica micro-spheres on a single-crystalline silicon (Si) substrate. So far, the outcome of this kind of near-field patterning has been related to the simultaneous, parallel surface-structuring of large areas either by top hat or Gaussian laser intensity distributions. We attempt to explore the possibility of using the same technique in order to produce single, direct writing of features. This could be of advantage for applications in which only some areas need to be patterned (i.e. local area selective patterning) or single lines are required (e.g. a particular micro/nano-fluidic channel). A diode pumped Nd:YVO4 laser system (wavelength of 532 nm, pulse duration of 8 ns, repetition rate of 30 kHz) with a computer-controlled 3 axis galvanometer beam scanner was employed to write user-defined patterns through the particle lens array on the Si substrate. After laser irradiation, the obtained patterns which are in the micro-scale were composed of sub-micro/micro-holes or bumps. The micro-pattern resolution depends on the dimension of both the micro-sphere’s diameter and the beam’s spot size. The developed technique could potentially be employed to fabricate photonic crystal structures mimicking nature’s butterfly wings and anti-reflective “moth eye” arrays for photovoltaic cells.

Laser Direct Writing of Tree-Shaped Hierarchical Cones on a Superhydrophobic Film for High-Efficiency Water Collection.

Science.gov (United States)

Wang, Meng; Liu, Qian; Zhang, Haoran; Wang, Chuang; Wang, Lei; Xiang, Bingxi; Fan, Yongtao; Guo, Chuan Fei; Ruan, Shuangchen

2017-08-30

Directional water collection has stimulated a great deal of interest because of its potential applications in the field of microfluidics, liquid transportation, fog harvesting, and so forth. There have been some bio or bioinspired structures for directional water collection, from one-dimensional spider silk to two-dimensional star-like patterns to three-dimensional Nepenthes alata. Here we present a simple way for the accurate design and highly controllable driving of tiny droplets: by laser direct writing of hierarchical patterns with modified wettability and desired geometry on a superhydrophobic film, the patterned film can precisely and directionally drive tiny water droplets and dramatically improve the efficiency of water collection with a factor of ∼36 compared with the original superhydrophobic film. Such a patterned film might be an ideal platform for water collection from humid air and for planar microfluidics without tunnels.

Direct UV-written broadband directional broadband planar waveguide couplers

DEFF Research Database (Denmark)

Olivero, Massimo; Svalgaard, Mikael

2005-01-01

We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation.......We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation....

Amplitudes for multiphoton quantum processes in linear optics

International Nuclear Information System (INIS)

UrIas, Jesus

2011-01-01

The prominent role that linear optical networks have acquired in the engineering of photon states calls for physically intuitive and automatic methods to compute the probability amplitudes for the multiphoton quantum processes occurring in linear optics. A version of Wick's theorem for the expectation value, on any vector state, of products of linear operators, in general, is proved. We use it to extract the combinatorics of any multiphoton quantum processes in linear optics. The result is presented as a concise rule to write down directly explicit formulae for the probability amplitude of any multiphoton process in linear optics. The rule achieves a considerable simplification and provides an intuitive physical insight about quantum multiphoton processes. The methodology is applied to the generation of high-photon-number entangled states by interferometrically mixing coherent light with spontaneously down-converted light.

Amplitudes for multiphoton quantum processes in linear optics

Science.gov (United States)

Urías, Jesús

2011-07-01

The prominent role that linear optical networks have acquired in the engineering of photon states calls for physically intuitive and automatic methods to compute the probability amplitudes for the multiphoton quantum processes occurring in linear optics. A version of Wick's theorem for the expectation value, on any vector state, of products of linear operators, in general, is proved. We use it to extract the combinatorics of any multiphoton quantum processes in linear optics. The result is presented as a concise rule to write down directly explicit formulae for the probability amplitude of any multiphoton process in linear optics. The rule achieves a considerable simplification and provides an intuitive physical insight about quantum multiphoton processes. The methodology is applied to the generation of high-photon-number entangled states by interferometrically mixing coherent light with spontaneously down-converted light.

Hard X-ray-induced optical luminescence via biomolecule-directed metal clusters†

Science.gov (United States)

Pratx, Guillem; Sun, Conroy; Sakamoto, Masanori; Ahmad, Moiz; Volotskova, Olga; Ong, Qunxiang; Teranishi, Toshiharu; Harada, Yoshie

2014-01-01

Here, we demonstrate that biomolecule-directed metal clusters are applicable in the study of hard X-ray excited optical luminescence, promising a new direction in the development of novel X-ray-activated imaging probes. PMID:24463467

Null geodesics and embedding diagrams of the interior Schwarzschild--de Sitter spacetimes with uniform density

International Nuclear Information System (INIS)

Stuchlik, Zdenek; Hledik, Stanislav; Soltes, Jiri; Ostgaard, Erlend

2001-01-01

Null geodesics and embedding diagrams of central planes in the ordinary space geometry and the optical reference geometry of the interior Schwarzschild--de Sitter spacetimes with uniform density are studied. For completeness, both positive and negative values of the cosmological constant are considered. The null geodesics are restricted to the central planes of these spacetimes, and their properties can be reflected by an 'effective potential.' If the interior spacetime is extremely compact, the effective potential has a local maximum corresponding to a stable circular null geodesic around which bound null geodesics are concentrated. The upper limit on the size of the interior spacetimes containing bound null geodesics is R=3M, independently of the value of the cosmological constant. The embedding diagrams of the central planes of the ordinary geometry into three-dimensional Euclidean space are well defined for the complete interior of all spacetimes with a repulsive cosmological constant, but the planes cannot be embedded into the Euclidean space in the case of spacetimes with subcritical values of an attractive cosmological constant. On the other hand, the embedding diagrams of the optical geometry are well defined for all of the spacetimes, and the turning points of these diagrams correspond to the radii of the circular null geodesics. All the embedding diagrams, for both the ordinary and optical geometry, are smoothly matched to the corresponding embedding diagrams of the external vacuum Schwarzschild--de Sitter spacetimes

Synthesis of Ag and Au nanoparticles embedded in carbon film: Optical, crystalline and topography analysis

Science.gov (United States)

Gholamali, Hediyeh; Shafiekhani, Azizollah; Darabi, Elham; Elahi, Seyed Mohammad

2018-03-01

Atomic force microscopy (AFM) images give valuable information about surface roughness of thin films based on the results of power spectral density (PSD) through the fast Fourier transform (FFT) algorithms. In the present work, AFM data are studied for silver and gold nanoparticles (Ag NPs a-C: H and Au NPs a-C: H) embedded in amorphous hydrogenated carbon films and co-deposited on glass substrate via of RF-Sputtering and RF-Plasma Enhanced Chemical Vapor Deposition methods. Here, the working gas is acetylene and the targets are Ag and Au. While time and power are constant, the only variable parameter in this study is initial pressure. In addition, the crystalline structure of Ag NPs a-C: H and Au NPs a-C: H are studied using X-ray diffraction (XRD). UV-visible spectrophotometry will also investigate optical properties and localized surface plasmon resonance (LSPR) of samples.

FIBER-OPTIC BIOSENSOR FOR DIRECT DETERMINATION OF ORGANOPHOSPHATE NERVE AGENTS. (R823663)

Science.gov (United States)

A fiber-optic enzyme biosensor for the direct measurement of organophosphate nerveagents was developed. The basic element of this biosensor is organophosphorus hydrolaseimmobilized on a nylon membrane and attached to the common end of a bifurcated optical fiberbundle....

TRAVEL WRITING: AN APPLICATION OF WRITING WORKSHOP TO ENHANCE STUDENTS’S CREATIVE WRITING

Directory of Open Access Journals (Sweden)

Prayudias Margawati

2014-10-01

Full Text Available Writing is often assumed as uneasy skill to either learn or teach. For students, they find it difficult to develop ideas in writing. On the other hand, teachers, many of them, only ready with the materials but confuse with the appropriate ways to teach. This paper intends to describe and discuss a method of teaching writing namely writing workshop to improve students’ writing skill through travel writing. Writing workshop proposed by Calkins that consists of mini lesson, work time, peer conferring and/or response groups, share sessions, and publication celebration is applied in writing class for methodological purposes. In mini lesson, teacher offers something to the class that is meant to introduce a writing strategy done at the beginning of the workshop. During work time point, students start their new piece of writing. Teacher moves among students conferring with them while checking their works. Peer conferences or response groups provide a forum for students to talk about works in progress. When students work in group, one of them could arrange his/ her group needs during the work time. A share session may be varied, one possible way is each group shares their process of writing to other students. At the end of writing class, student writers come together to publish and/ or celebrate their final work. The publication could be in the form of portfolio, students’ diary, blog, or others. Travel writing genre is chosen as it could develop students’ creativity in describing/ narrating their own stories during, let say holiday or things they used to see on the way home weekly or monthly. Furthermore, travel writing as the product of creative writing teaches the readers of values, characteristics, and way of life. Last but not least, a professional writing teacher should set the writing workshop components in variety ways to achieve effective running-class.

EXPLICIT PLANNING FOR PARAGRAPH WRITING CLASS

Directory of Open Access Journals (Sweden)

Lestari Setyowati

2017-11-01

Full Text Available The purpose of the study is to improve the students writing ability for paragraph writing class. The subjects of the study were 37 students of English Education Study Program who joined the paragraph writing class. The design of the study was Classroom Action Research with two cycles. Cycle 1 consisted of three meetings, and cycle 2 consisted of two meetings. The types of explicit planning used in the action research were word listing and word mapping with phrases and sentence for detail.  The instruments used were direct writing test, observation, and  documentation of students’ reflective essay. To score the students’ writing, two raters  were asked to rate the composition by using Jacobs ESL Composition profile scoring rubric. The finding shows that the use of explicit planning was able to improve the students’ paragraph writing performance, indicated with the achievement of the criteria of success. The students’ mean improved from cycle 1 (74.62  to cycle2 (76.78. Although explicit planning instruction was able to help the students to write better, data from their self-reflection essay showed that many of the students preferred to use free writing instead of explicit planning instruction.

Dynamic strain distribution measurement and crack detection of an adhesive-bonded single-lap joint under cyclic loading using embedded FBG

International Nuclear Information System (INIS)

Ning, Xiaoguang; Murayama, Hideaki; Kageyama, Kazuro; Wada, Daichi; Kanai, Makoto; Ohsawa, Isamu; Igawa, Hirotaka

2014-01-01

In this study, the dynamic strain distribution measurement of an adhesive-bonded single-lap joint was carried out in a cyclic load test using a fiber Bragg grating (FBG) sensor embedded into the adhesive/adherend interface along the overlap length direction. Unidirectional carbon fiber reinforced plastic (CFRP) substrates were bonded by epoxy resin to form the joint, and the FBG sensor was embedded into the surface of one substrate during its curing. The measurement was carried out with a sampling rate of 5 Hz by the sensing system, based on the optical frequency domain reflectometry (OFDR) throughout the test. A finite element analysis (FEA) was performed for the measurement evaluation using a three-dimensional model, which included the embedded FBG sensor. The crack detection method, based on the longitudinal strain distribution measurement, was introduced and performed to estimate the cracks that occurred at the adhesive/adherend interface in the test. (paper)

UHD Video Transmission over Bi-Directional Underwater Wireless Optical Communication

KAUST Repository

Al-Halafi, Abdullah

2018-04-02

In this paper, we experimentally demonstrate for the first time a bi-directional underwater wireless optical communication system that is capable of transmitting an ultra high definition real-time video using a downlink channel while simultaneously receiving the feedback messages on the uplink channel. The links extend up to 4.5 m using QPSK, 16-QAM and 64-QAM modulations. The system is built using software defined platforms connected to TO-9 packaged pigtailed 520 nm directly modulated green laser diode (LD) with 1.2 GHz bandwidth as the optical transmitter for video streaming on the downlink, and an avalanche photodiode (APD) module as the downlink receiver. The uplink channel is connected to another pigtailed 450 nm directly modulated blue LD with 1.2 GHz bandwidth as the optical uplink transmitter for the feedback channel, and to a second APD as the uplink receiver. We perform laboratory experiments on different water types. The measured throughput is 15 Mbps for QPSK, and 30 Mbps for both 16-QAM and 64-QAM. We evaluate the quality of the received live video streams using Peak Signal-to-Noise Ratio and achieve values up to 16 dB for 64-QAM when streaming UHD video in harbor II water and 22 dB in clear ocean.

UHD Video Transmission over Bi-Directional Underwater Wireless Optical Communication

KAUST Repository

Al-Halafi, Abdullah; Shihada, Basem

2018-01-01

In this paper, we experimentally demonstrate for the first time a bi-directional underwater wireless optical communication system that is capable of transmitting an ultra high definition real-time video using a downlink channel while simultaneously receiving the feedback messages on the uplink channel. The links extend up to 4.5 m using QPSK, 16-QAM and 64-QAM modulations. The system is built using software defined platforms connected to TO-9 packaged pigtailed 520 nm directly modulated green laser diode (LD) with 1.2 GHz bandwidth as the optical transmitter for video streaming on the downlink, and an avalanche photodiode (APD) module as the downlink receiver. The uplink channel is connected to another pigtailed 450 nm directly modulated blue LD with 1.2 GHz bandwidth as the optical uplink transmitter for the feedback channel, and to a second APD as the uplink receiver. We perform laboratory experiments on different water types. The measured throughput is 15 Mbps for QPSK, and 30 Mbps for both 16-QAM and 64-QAM. We evaluate the quality of the received live video streams using Peak Signal-to-Noise Ratio and achieve values up to 16 dB for 64-QAM when streaming UHD video in harbor II water and 22 dB in clear ocean.

Embedded micro-sensor for monitoring pH in concrete structures

Science.gov (United States)

Srinivasan, Rengaswamy; Phillips, Terry E.; Bargeron, C. Brent; Carlson, Micah A.; Schemm, Elizabeth R.; Saffarian, Hassan M.

2000-04-01

Three major causes of corrosion of steel in concrete are chloride ions (Cl-), temperature (T) and acidity (pH). Under normal operating temperatures and with pH above 13, steel does not undergo pitting corrosion. In presence of Cl-, if the pH decreases below 12, the probability of pitting increases. Acid rain and atmospheric carbon dioxide cause the pH to drop in concrete, often leading to corrosion of the structure with the concomitant cost of repair or replacement. Currently, the pH level in concrete is estimated through destructive testing of the structures. Glass ISFET, and other pH sensors that need maintenance and calibration cannot be embedded in concrete. In this paper, we describe an inexpensive solid state pH sensor that can be embedded in concrete, to detect pH changes at the early stages. It employs a chemical reagent, trinitrobenzenesulfonic acid (TNBS) that exhibits changes in optical properties in the 12 - 14 pH range, and is held in a film of a sol-gel/TNBS composite on an optically transparent surface. A simple LED/filter/photodiode transducer monitors pH-induced changes in TNBS. Such a device needs no periodic calibration or maintenance. The optical window, the light-source and sensor can be easily housed and encapsulated in a chemically inert structure, and embedded in concrete.

Laser direct writing of thin-film copper structures as a modification of lithographic processes

International Nuclear Information System (INIS)

Meyer, F; Ostendorf, A; Stute, U

2007-01-01

This paper presents a flexible, mask-free and efficient technique for UV-laser micropatterning of photosensitive resist by laser direct writing (LDW). Photo resist spun on gold sputtered silicon wafers has been laser structured by a scanner guided 266nm DPSSL and electroplated. Ablation behaviour and optimum seed layer preparation in relation to parameters like pulse energy, scanning speed and number of scanned cycles and the electroplating results are discussed. The resulting adhesive strength was measured by a μ-sear device and the gold seed layer-plated copper interface investigated by SEM and EDX to explain correlation to identified bonding behaviour. Improved adhesive strength was observed with higher laser pulse energy and reduced number of cycle

Reading and Writing as Academic Literacy in EAP Program of Indonesian Leaners

Directory of Open Access Journals (Sweden)

Imroatus Solikhah

2015-12-01

Full Text Available This study investigates academic literacy imposed in reading and writing for academic purposes in the EAP program. This study uses descriptive design elaborating data from curriculum documents and interviews.  Involving 45 participants from IAIN Surakarta and Veteran University, data were analyzed using constant-comparison and inductive analysis tecniques. The study diseovers that academic literacy is prominent to serve and recently it has been the growing learning outcomes universities should provide besides discipline and experise. Academic literacy in EAP program is embedded into academic vocabulary, grammar, reading and writing for academic purposes.  Consequently, academic literacy should be incurred in the curriculum, syllabus, aims and objectives, and teaching materials.

EMBEDding the CEFR in Academic Writing Assessment : A case study in training and standardization

NARCIS (Netherlands)

Haines, Kevin; Lowie, Wander; Jansma, Petra; Schmidt, Nicole

2013-01-01

The CEFR is increasingly being used as the framework of choice for the assessment of language proficiency at universities across Europe. However, to attain consistent assessment, familiarization and standardization are essential. In this paper we report a case study of embedding a standardization

Flexible Microsphere-Embedded Film for Microsphere-Enhanced Raman Spectroscopy.

Science.gov (United States)

Xing, Cheng; Yan, Yinzhou; Feng, Chao; Xu, Jiayu; Dong, Peng; Guan, Wei; Zeng, Yong; Zhao, Yan; Jiang, Yijian

2017-09-27

Dielectric microspheres with extraordinary microscale optical properties, such as photonic nanojets, optical whispering-gallery modes (WGMs), and directional antennas, have drawn interest in many research fields. Microsphere-enhanced Raman spectroscopy (MERS) is an alternative approach for enhanced Raman detection by dielectric microstructures. Unfortunately, fabrication of microsphere monolayer arrays is the major challenge of MERS for practical applications on various specimen surfaces. Here we report a microsphere-embedded film (MF) by immersing a highly refractive microsphere monolayer array in the poly(dimethylsiloxane) (PDMS) film as a flexible MERS sensing platform for one- to three-dimensional (1D to 3D) specimen surfaces. The directional antennas and wave-guided whispering-gallery modes (WG-WGMs) contribute to the majority of Raman enhancement by the MFs. Moreover, the MF can be coupled with surface-enhanced Raman spectroscopy (SERS) to provide an extra >10-fold enhancement. The limit of detection is therefore improved for sensing of crystal violet (CV) and Sudan I molecules in aqueous solutions at concentrations down to 10 -7 M. A hybrid dual-layer microsphere enhancer, constructed by depositing a MF onto a microsphere monolayer array, is also demonstrated, wherein the WG-WGMs become dominant and boost the enhancement ratio >50-fold. The present work opens up new opportunities for design of cost-effective and flexible MERS sensing platforms as individual or associated techniques toward practical applications in ultrasensitive Raman detection.

Optical Degradation of Colloidal Eu-Complex Embedded in Silica Glass Film Using Reprecipitation and Sol-Gel Methods.

Science.gov (United States)

Fukuda, Takeshi; Kurabayashi, Tomokazu; Yamaki, Tatsuki

2016-04-01

A reprecipitation method has been investigated for fabricating colloidal nanoparticles using Eu-complex. Herein, we investigated optical degradation characteristics of (1,10-phenanthroline)tris [4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato]europium(III) colloidal nanoparticles, which were embedded into a silica glass film fabricated by a conventional sol-gel process. At first, we tried several types of good solvents for the reprecipitation method, and dimethyl sulfoxide (DMSO) is found to be a suitable solvent for realizing the small diameter and the high long-term stability against the ultraviolet irradiation even though the boing point of DMSO is higher than that of water used as a poor solvent. By optimizing the good solvent and the concentration of Eu-complex, the relative photoluminescence intensity of 0.96 was achieved even though the ultraviolet light was continuously irradiated for 90 min. In addition, the average diameter of 106 nm was achieved when DMSO was used as a good solvent, resulting in the high transmittance at a visible wavelength region. Therefore, we can achieve the transparent emissive thin film with a center wavelength of 612 nm, and the optical degradation was drastically reduced by forming nanoparticles.

RadSensor: Xray Detection by Direct Modulation of an Optical Probe Beam

International Nuclear Information System (INIS)

Lowry, M E; Bennett, C V; Vernon, S P; Bond, T; Welty, R; Behymer, E; Petersen, H; Krey, A; Stewart, R; Kobayashi, N P; Sperry, V; Stephan, P; Reinhardt, C; Simpson, S; Stratton, P; Bionta, R; McKernan, M; Ables, E; Ott, L; Bond, S; Ayers, J.; Landen, O L; Bell, P M

2003-01-01

We present a new x-ray detection technique based on optical measurement of the effects of x-ray absorption and electron hole pair creation in a direct band-gap semiconductor. The electron-hole pairs create a frequency dependent shift in optical refractive index and absorption. This is sensed by simultaneously directing an optical carrier beam through the same volume of semiconducting medium that has experienced an xray induced modulation in the electron-hole population. If the operating wavelength of the optical carrier beam is chosen to be close to the semiconductor band-edge, the optical carrier will be modulated significantly in phase and amplitude. This approach should be simultaneously capable of very high sensitivity and excellent temporal response, even in the difficult high-energy xray regime. At xray photon energies near 10 keV and higher, we believe that sub-picosecond temporal responses are possible with near single xray photon sensitivity. The approach also allows for the convenient and EMI robust transport of high-bandwidth information via fiber optics. Furthermore, the technology can be scaled to imaging applications. The basic physics of the detector, implementation considerations, and preliminary experimental data are presented and discussed

Direct fabrication of polymer micro-lens array

Science.gov (United States)

Coppola, S.; Pagliarulo, V.; Vespini, V.; Nasti, G.; Olivieri, F.; Grilli, S.; Ferraro, P.

2017-06-01

In order to break the rigidity of classic lithographic techniques, a flexible pyro-electric-electrohydrodynamic (EHD) inkjet printing is presented. In particular, here is showed a method able to manipulate highly viscous polymers, usable for optical integrated devices. The system proposed reaches spatial resolution up to the nano-scale and can print, for instance, nano-particles and high viscous polymer solutions. This technique allows writing patterns directly onto a substrate of interest in 2D or in 3D configuration and is studied in order to overcome limitations in terms of type of materials, geometry and thickness of the substrate. In the present work, we show the potential of pyro-EHD printing in fields as optics and micro-fluidics. A micro-channel chip is functionalized with a PDMS-made micro-lenses array, directly printed on the chip. The geometric properties and the quality of the lenses are evaluated by a Digital Holography (DH) analysis.

What is technical writing? Prolegomenon to a contextual definition

Science.gov (United States)

Barton, B. F.; Barton, M. S.

1981-01-01

The question, "What is Technical Writing?", is addressed. Interest about the stance a teacher assumes in a classroom, the orientation of textbooks, and the shape of curricula are considered. Technical writing is considered of age, definitions abound and the time is ripe for a metaperspective on the question. This analyzes pitfalls in representative definitions of technical writing suggest a direction for future inquiry.

Scalable High-Performance Ultraminiature Graphene Micro-Supercapacitors by a Hybrid Technique Combining Direct Writing and Controllable Microdroplet Transfer.

Science.gov (United States)

Shen, Daozhi; Zou, Guisheng; Liu, Lei; Zhao, Wenzheng; Wu, Aiping; Duley, Walter W; Zhou, Y Norman

2018-02-14

Miniaturization of energy storage devices can significantly decrease the overall size of electronic systems. However, this miniaturization is limited by the reduction of electrode dimensions and the reproducible transfer of small electrolyte drops. This paper reports first a simple scalable direct writing method for the production of ultraminiature microsupercapacitor (MSC) electrodes, based on femtosecond laser reduced graphene oxide (fsrGO) interlaced pads. These pads, separated by 2 μm spacing, are 100 μm long and 8 μm wide. A second stage involves the accurate transfer of an electrolyte microdroplet on top of each individual electrode, which can avoid any interference of the electrolyte with other electronic components. Abundant in-plane mesopores in fsrGO induced by a fs laser together with ultrashort interelectrode spacing enables MSCs to exhibit a high specific capacitance (6.3 mF cm -2 and 105 F cm -3 ) and ∼100% retention after 1000 cycles. An all graphene resistor-capacitor (RC) filter is also constructed by combining the MSC and a fsrGO resistor, which is confirmed to exhibit highly enhanced performance characteristics. This new hybrid technique combining fs laser direct writing and precise microdroplet transfer easily enables scalable production of ultraminiature MSCs, which is believed to be significant for practical application of micro-supercapacitor microelectronic systems.

Direct writing of half-meter long CNT based fiber for flexible electronics.

Science.gov (United States)

Huang, Sihan; Zhao, Chunsong; Pan, Wei; Cui, Yi; Wu, Hui

2015-03-11

Rapid construction of flexible circuits has attracted increasing attention according to its important applications in future smart electronic devices. Herein, we introduce a convenient and efficient "writing" approach to fabricate and assemble ultralong functional fibers as fundamental building blocks for flexible electronic devices. We demonstrated that, by a simple hand-writing process, carbon nanotubes (CNTs) can be aligned inside a continuous and uniform polymer fiber with length of more than 50 cm and diameters ranging from 300 nm to several micrometers. The as-prepared continuous fibers exhibit high electrical conductivity as well as superior mechanical flexibility (no obvious conductance increase after 1000 bending cycles to 4 mm diameter). Such functional fibers can be easily configured into designed patterns with high precision according to the easy "writing" process. The easy construction and assembly of functional fiber shown here holds potential for convenient and scalable fabrication of flexible circuits in future smart devices like wearable electronics and three-dimensional (3D) electronic devices.

Interferometric fiber-optic sensor embedded in a spark plug for in-cylinder pressure measurement in engines.

Science.gov (United States)

Bae, Taehan; Atkins, Robert A; Taylor, Henry F; Gibler, William N

2003-02-20

Pressure sensing in an internal combustion engine with an intrinsic fiber Fabry-Perot interferometer (FFPI) integrated with a spark plug is demonstrated for the first time. The spark plug was used for the ignition of the cylinder in which it was mounted. The FFPI element, protected with a copper/gold coating, was embedded in a groove in the spark-plug housing. Gas pressure inthe engine induced longitudinal strain in this housing, which was also experienced by the fiber-optic sensing element. The sensor was monitored with a signal conditioning unit containing a chirped distributed-feedback laser. Pressure sensitivities as high as 0.00339 radians round-trip phase shift per pounds per square inch of pressure were observed. Measured pressure versus time traces showed good agreement with those from a piezoelectric reference sensor mounted in the same engine cylinder.

International Conference on Integrated Optical Circuit Engineering, 1st, Cambridge, MA, October 23-25, 1984, Proceedings

Science.gov (United States)

Ostrowsky, D. B.; Sriram, S.

Aspects of waveguide technology are explored, taking into account waveguide fabrication techniques in GaAs/GaAlAs, the design and fabrication of AlGaAs/GaAs phase couplers for optical integrated circuit applications, ion implanted GaAs integrated optics fabrication technology, a direct writing electron beam lithography based process for the realization of optoelectronic integrated circuits, and advances in the development of semiconductor integrated optical circuits for telecommunications. Other subjects examined are related to optical signal processing, optical switching, and questions of optical bistability and logic. Attention is given to acousto-optic techniques in integrated optics, acousto-optic Bragg diffraction in proton exchanged waveguides, optical threshold logic architectures for hybrid binary/residue processors, integrated optical modulation and switching, all-optic logic devices for waveguide optics, optoelectronic switching, high-speed photodetector switching, and a mechanical optical switch.

Direct Laser Writing of Low-Density Interdigitated Foams for Plasma Drive Shaping [Direct Laser Writing of Low Density Nanostitched Foams for Plasma Drive Shaping

International Nuclear Information System (INIS)

Oakdale, James S.; Smith, Raymond F.; Forien, Jean-Baptiste; Smith, William L.; Ali, Suzanne J.

2017-01-01

Monolithic porous bulk materials have many promising applications ranging from energy storage and catalysis to high energy density physics. High resolution additive manufacturing techniques, such as direct laser writing via two photon polymerization (DLW-TPP), now enable the fabrication of highly porous microlattices with deterministic morphology control. In this work, DLW-TPP is used to print millimeter-sized foam reservoirs (down to 0.06 g cm –3 ) with tailored density-gradient profiles, where density is varied by over an order of magnitude (for instance from 0.6 to 0.06 g cm –3 ) along a length of <100 µm. Taking full advantage of this technology, however, is a multiscale materials design problem that requires detailed understanding of how the different length scales, from the molecular level to the macroscopic dimensions, affect each other. The design of these 3D-printed foams is based on the brickwork arrangement of 100 × 100 × 16 µm 3 log-pile blocks constructed from sub-micrometer scale features. A block-to-block interdigitated stitching strategy is introduced for obtaining high density uniformity at all length scales. Lastly, these materials are used to shape plasma-piston drives during ramp-compression of targets under high energy density conditions created at the OMEGA Laser Facility.

Analog direct-modulation behavior of semiconductor laser transmitters using optical FM demodulation

NARCIS (Netherlands)

Yabre, G.S.

1998-01-01

In this paper, we report a theoretical investigation of the analog modulation performance of a semiconductor laser transmitter which employs the direct optical FM demodulation. This analysis is based on the rate equations in which Langevin noise functions are included. The optical FM response has

Characterization of fatigue resistance in photochromic composite materials for 3D rewritable optical memory applications

International Nuclear Information System (INIS)

Samoylova, Elena; Dallari, William; Allione, Marco; Pignatelli, Francesca; Marini, Lara; Cingolani, Roberto; Diaspro, Alberto; Athanassiou, Athanassia

2013-01-01

Highlights: • Fatigue resistance of diarylethene–polymer composites was tested with optical absorption and fluorescence methods upon repetitive UV–VIS irradiation. • Significant differences in fatigue were found in different polymeric matrices and in one-photon and two-photon excitation experiments. • Several explanations for fatigue resistance of the composites are proposed based on the physico-chemical properties of the diarylethenes and polymeric matrices. -- Abstract: Fatigue resistance of the photochromic diarylethene molecules 1,2-bis[2-methylbenzo[b]thyophen-3-yl] -3,3,4,4,5,5-hexafluoro-1-cyclopentene embedded in three different acrylic polymers is studied upon multiple coloration–decoloration cycles. The resistance to photofatigue is found to be different in the three polymeric materials when one-photon excitation was used for the reversible photoconversion experiment. In particular, the photochromic molecules lose their photoisomerization ability faster if they are embedded in poly(methyl methacrylate) (PMMA) with respect to poly(ethyl methacrylate-co-methyl acrylate) (PEMMA) and poly(ethyl methacrylate) (PEMA). We propose several explanations based on the physico-chemical properties of the matrix and of the photochromic molecules. In the case of two-photon excitation, which is necessary for 3D optical writing, the fatigue resistance is found to be poorer than in the one-photon case. The accelerated photodegradation can be assigned to the non-linear nature of interaction between the polymeric composite material and light

Characterization of fatigue resistance in photochromic composite materials for 3D rewritable optical memory applications

Energy Technology Data Exchange (ETDEWEB)

Samoylova, Elena, E-mail: Elena.Samoylova@physik.uni-muenchen.de [Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Dallari, William; Allione, Marco; Pignatelli, Francesca; Marini, Lara; Cingolani, Roberto; Diaspro, Alberto [Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Athanassiou, Athanassia, E-mail: athanassia.athanassiou@iit.it [Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Center for Biomolecular Nanotechnologies-Unile, Istituto Italiano di Tecnologia, via Barsanti, 73010 Arnesano, Lecce (Italy)

2013-06-01

Highlights: • Fatigue resistance of diarylethene–polymer composites was tested with optical absorption and fluorescence methods upon repetitive UV–VIS irradiation. • Significant differences in fatigue were found in different polymeric matrices and in one-photon and two-photon excitation experiments. • Several explanations for fatigue resistance of the composites are proposed based on the physico-chemical properties of the diarylethenes and polymeric matrices. -- Abstract: Fatigue resistance of the photochromic diarylethene molecules 1,2-bis[2-methylbenzo[b]thyophen-3-yl] -3,3,4,4,5,5-hexafluoro-1-cyclopentene embedded in three different acrylic polymers is studied upon multiple coloration–decoloration cycles. The resistance to photofatigue is found to be different in the three polymeric materials when one-photon excitation was used for the reversible photoconversion experiment. In particular, the photochromic molecules lose their photoisomerization ability faster if they are embedded in poly(methyl methacrylate) (PMMA) with respect to poly(ethyl methacrylate-co-methyl acrylate) (PEMMA) and poly(ethyl methacrylate) (PEMA). We propose several explanations based on the physico-chemical properties of the matrix and of the photochromic molecules. In the case of two-photon excitation, which is necessary for 3D optical writing, the fatigue resistance is found to be poorer than in the one-photon case. The accelerated photodegradation can be assigned to the non-linear nature of interaction between the polymeric composite material and light.

Tailored silver grid as transparent electrodes directly written by femtosecond laser

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yuan-Yuan; Ren, Xue-Liang [Laboratory of Organic NanoPhotonics and Laboratory of Bio-Inspired Smart Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, No. 29, Zhongguancun East Road, Beijing 100190 (China); University of Chinese Academy of Sciences, No. 29, Zhongguancun East Road, Beijing 100190 (China); Zheng, Mei-Ling, E-mail: zhengmeiling@mail.ipc.ac.cn, E-mail: xmduan@mail.ipc.ac.cn; Dong, Xian-Zi; Jin, Feng; Liu, Jie; Zhao, Zhen-Sheng [Laboratory of Organic NanoPhotonics and Laboratory of Bio-Inspired Smart Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, No. 29, Zhongguancun East Road, Beijing 100190 (China); Duan, Xuan-Ming, E-mail: zhengmeiling@mail.ipc.ac.cn, E-mail: xmduan@mail.ipc.ac.cn [Laboratory of Organic NanoPhotonics and Laboratory of Bio-Inspired Smart Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, No. 29, Zhongguancun East Road, Beijing 100190 (China); Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, No. 266 Fangzheng Ave., Shuitu Technology Development Zone, Beibei District, Chongqing 400714 (China)

2016-05-30

We present the design and realization of silver grid transparent electrodes (SGTEs) easily fabricated by femtosecond laser direct writing of silver aqueous solution. The fabricated SGTEs with a sheet resistance down to 47 Ω/□ and optical transmittance up to 93% are demonstrated. These sheet resistance and transmittance values are comparable to commercially available indium tin oxide. High uniform morphology of the directly written SGTEs results in the ultra-stable tailored performance parameter at electronic and optical fields. The sheet resistance and transmittance can be tailored precisely by manipulating the filling fraction of the uniform SGTEs. This study provides an approach for creating SGTEs in a controllable fashion, and the SGTEs exhibit high transmittance and low sheet resistance, which could open up new avenues towards widespread application in electronics, photovoltaics, and optoelectronics.

Relating beliefs in writing skill malleability to writing performance: The mediating role of achievement goals and self-efficacy

Directory of Open Access Journals (Sweden)

Teresa Limpo

2017-10-01

Full Text Available It is well established that students’ beliefs in skill malleability influence their academic performance. Specifically, thinking of ability as an incremental (vs. fixed trait is associated with better outcomes. Though this was shown across many domains, little research exists into these beliefs in the writing domain and into the mechanisms underlying their effects on writing performance. The aim of this study was twofold: to gather evidence on the validity and reliability of instruments to measure beliefs in skill malleability, achievement goals, and self-efficacy in writing; and to test a path-analytic model specifying beliefs in writing skill malleability to influence writing performance, via goals and self-efficacy. For that, 196 Portuguese students in Grades 7-8 filled in the instruments and wrote an opinion essay that was assessed for writing performance. Confirmatory factor analyses supported instruments’ validity and reliability. Path analysis revealed direct effects from beliefs in writing skill malleability to mastery goals (ß = .45; from mastery goals to self-efficacy for conventions, ideation, and self-regulation (ß = .27, .42, and .42, respectively; and from self-efficacy for self-regulation to writing performance (ß = .16; along with indirect effects from beliefs in writing skill malleability to self-efficacy for self-regulation via mastery goals (ß = .19, and from mastery goals to writing performance via self-efficacy for self-regulation (ß = .07. Overall, students’ mastery goals and self-efficacy for self-regulation seem to be key factors underlying the link between beliefs in writing skill malleability and writing performance. These findings highlight the importance of attending to motivation-related components in the teaching of writing.

Directional radiation of Babinet-inverted optical nanoantenna integrated with plasmonic waveguide

Science.gov (United States)

Kim, Jineun; Roh, Young-Geun; Cheon, Sangmo; Jeong Kim, Un; Hwang, Sung Woo; Park, Yeonsang; Lee, Chang-Won

2015-07-01

We present a Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide. Using an integrated nanoantenna, we can couple the plasmon guide mode in a metal-insulator-metal (MIM) structure into the resonant antenna feed directly. The resonantly excited feed slot then radiates to free space and generates a magnetic dipole-like far-field pattern. The coupling efficiency of the integrated nanoantenna is calculated as being approximately 19% using a three-dimensional finite-difference time-domain (3D FDTD) simulation. By adding an auxiliary groove structure along with the feed, the radiation direction can be controlled similar to an optical Yagi-Uda antenna. We also determine, both theoretically and experimentally, that groove depth plays a significant role to function groove structure as a reflector or a director. The demonstrated Babinet-inverted optical nanoantenna integrated with a plasmonic waveguide can be used as a “plasmonic via” in plasmonic nanocircuits.

Fully Packaged Carbon Nanotube Supercapacitors by Direct Ink Writing on Flexible Substrates.

Science.gov (United States)

Chen, Bolin; Jiang, Yizhou; Tang, Xiaohui; Pan, Yayue; Hu, Shan

2017-08-30

The ability to print fully packaged integrated energy storage components (e.g., supercapacitors) is of critical importance for practical applications of printed electronics. Due to the limited variety of printable materials, most studies on printed supercapacitors focus on printing the electrode materials but rarely the full-packaged cell. This work presents for the first time the printing of a fully packaged single-wall carbon nanotube-based supercapacitor with direct ink writing (DIW) technology. Enabled by the developed ink formula, DIW setup, and cell architecture, the whole printing process is mask free, transfer free, and alignment free with precise and repeatable control on the spatial distribution of all constituent materials. Studies on cell design show that a wider electrode pattern and narrower gap distance between electrodes lead to higher specific capacitance. The as-printed fully packaged supercapacitors have energy and power performances that are among the best in recently reported planar carbon-based supercapacitors that are only partially printed or nonprinted.

CO2 laser direct writing of silver lines on epoxy resin from solid film

International Nuclear Information System (INIS)

Liu, J.G.; Chen, C.H.; Zheng, J.S.; Huang, J.Y.

2005-01-01

A technique of CO 2 laser direct writing from solid film was proposed in this paper. Patterns of silver lines were locally deposited on the non-conductive substrate using a preset layer of silver compound solid film, which was irradiated by focused CO 2 laser beam. The deposits were analyzed by XPS and EPMA. Results showed that metallic silver was dominant with an even distribution on the surface of the substrate, and part of the deposited silver had diffused into the substrate interior. The deposits had catalytic activity for the further electroless copper plating and had strong adhesion to the substrate. At last, the deposition mechanism and the dependence of the width of silver lines on the laser power and scan speed were roughly explored

Investigation of Writing Strategies, Writing Apprehension, and Writing Achievement among Saudi EFL-Major Students

Science.gov (United States)

Al Asmari, AbdulRahman

2013-01-01

The tenet of this study is to investigate the use of writing strategies in reducing writing apprehension and uncovering its effect on EFL students' writing achievement. It also attempts to explore associations between foreign language apprehension, writing achievement and writing strategies. The primary aims of the study were to explore the…

Whose Job Is It? Exploring Subject Tutor Roles in Addressing Students' Academic Writing via Essay Feedback

Science.gov (United States)

Court, Krista; Johnson, Helen

2016-01-01

Strong arguments have been forwarded for embedding academic writing development into the UK higher education curriculum and for subject tutors to facilitate this development (Hyland, 2000; Lea & Street, 2006; Monroe, 2003; Wingate, 2006). This small-scale case study explores subject tutors' practices and beliefs with regard to the provision of…

University writing

Directory of Open Access Journals (Sweden)

Miguel Zabalza Beraza

2013-01-01

Full Text Available Writing in the University is a basic necessity and a long-range educational purpose. One of the basic characteristics of the university context is that it requires writing both as a tool of communication and as a source of intellectual stimulation. After establishing the basic features of academic writing, this article analyzes the role of writing for students (writing to learn and for teachers (write to plan, to reflect, to document what has been done. The article also discusses the contributions of writing for both students and teachers together: writing to investigate. Finally, going beyond what writing is as academic tool, we conclude with a more playful and creative position: writing for pleasure and enjoyment.

Optical fibre sensing in metals by embedment in 3D printed metallic structures

Science.gov (United States)

Maier, R. R. J.; Havermann, D.; Schneller, O.; Mathew, J.; Polyzos, D.; MacPherson, W. N.; Hand, D. P.

2014-05-01

Additive manufacturing or 3D printing of structural components in metals has potential to revolutionise the manufacturing industry. Embedded sensing in such structures opens a route towards SMART metals, providing added functionality, intelligence and enhanced performance in many components. Such embedded sensors would be capable of operating at extremely high temperatures by utilizing regenerated fibre Bragg gratings and in-fibre Fabry-Perot cavities.

Positional Accuracy in Optical Trap-Assisted Nanolithography

Science.gov (United States)

Arnold, Craig B.; McLeod, Euan

2009-03-01

The ability to directly print patterns on size scales below 100 nm is important for many applications where the production or repair of high resolution and density features are important. Laser-based direct-write methods have the benefit of quickly and easily being able to modify and create structures on existing devices, but feature sizes are conventionally limited by diffraction. In this presentation, we show how to overcome this limit with a new method of probe-based near-field nanopatterning in which we employ a CW laser to optically trap and manipulate dispersed microspheres against a substrate using a 2-d Bessel beam optical trap. A secondary, pulsed nanosecond laser at 355 nm is directed through the bead and used to modify the surface below the microsphere, taking advantage of the near-field enhancement in order to produce materials modification with feature sizes under 100 nm. Here, we analyze the 3-d positioning accuracy of the microsphere through analytic modeling as a function of experimental parameters. The model is verified in all directions for our experimental conditions and is used to predict the conditions required for improved positional accuracy.

A synthesis of mathematics writing: Assessments, interventions, and surveys

Directory of Open Access Journals (Sweden)

Sarah R. Powell

2017-02-01

Full Text Available Mathematics standards in the United States describe communication as an essential part of mathematics. One outlet for communication is writing. To understand the mathematics writing of students, we conducted a synthesis to evaluate empirical research about mathematics writing. We identified 29 studies that included a mathematics-writing assessment, intervention, or survey for students in 1st through 12th grade. All studies were published between 1991 and 2015. The majority of assessments required students to write explanations to mathematical problems, and fewer than half scored student responses according to a rubric. Approximately half of the interventions involved the use of mathematics journals as an outlet for mathematics writing. Few intervention studies provided explicit direction on how to write in mathematics, and a small number of investigations provided statistical evidence of intervention efficacy. From the surveys, the majority of students expressed enjoyment when writing in mathematics settings but teachers reported using mathematics writing rarely. Across studies, findings indicate mathematics writing is used for a variety of purposes, but the quality of the studies is variable and more empirical research is needed.

Performance of direct and iterative algorithms on an optical systolic processor

Science.gov (United States)

Ghosh, A. K.; Casasent, D.; Neuman, C. P.

1985-11-01

The frequency-multiplexed optical linear algebra processor (OLAP) is treated in detail with attention to its performance in the solution of systems of linear algebraic equations (LAEs). General guidelines suitable for most OLAPs, including digital-optical processors, are advanced concerning system and component error source models, guidelines for appropriate use of direct and iterative algorithms, the dominant error sources, and the effect of multiple simultaneous error sources. Specific results are advanced on the quantitative performance of both direct and iterative algorithms in the solution of systems of LAEs and in the solution of nonlinear matrix equations. Acoustic attenuation is found to dominate iterative algorithms and detector noise to dominate direct algorithms. The effect of multiple spatial errors is found to be additive. A theoretical expression for the amount of acoustic attenuation allowed is advanced and verified. Simulations and experimental data are included.

Direct laser writing of auxetic structures: present capabilities and challenges

International Nuclear Information System (INIS)

Hengsbach, Stefan; Lantada, Andrés Díaz

2014-01-01

Auxetic materials (or metamaterials) are those with a negative Poisson ratio (NPR) and that display the unexpected property of lateral expansion when stretched, as well as an equal and opposing densification when compressed. Such geometries are being progressively employed in the development of novel products, especially in the fields of intelligent expandable actuators, shape morphing structures and minimally invasive implantable devices. Although several micromanufacturing technologies have already been applied to the development of auxetic geometries and devices, additional precision is needed to take full advantage of their special mechanical properties. In this study we present a very promising approach for the development of auxetic metamaterials and devices based on the use of direct laser writing. The process stands out for its precision and complex three-dimensional (3D) geometries attainable without the need of supporting structures. To our knowledge it represents one of the first examples of the application of this technology to the manufacture of auxetic geometries and mechanical metamaterials, with details even more remarkable than those shown in very recent studies, almost reaching the current limit of this additive manufacturing technology. We have used some special 3D auxetic designs whose remarkable NPR has been previously highlighted. (paper)

Investigation of optical properties of Cu/Ni multilayer nanowires embedded in etched ion-track template

Energy Technology Data Exchange (ETDEWEB)

Xie, Lu [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Yao, Huijun, E-mail: Yaohuijun@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Duan, Jinglai; Chen, Yonghui [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Lyu, Shuangbao [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Maaz, Khan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Nanomaterials Research Group, Physics Division, PINSTECH, Nilore 45650, Islamabad (Pakistan); Mo, Dan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liu, Jie, E-mail: J.Liu@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Sun, Youmei; Hou, Mingdong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2016-12-01

Graphical abstract: The schematic diagram of measurement of extinction spectra of Cu/Ni multilayer nanowire arrays embedded in the template after removing the gold/copper substrate. - Highlights: • The optical properties of Cu/Ni multilayer nanowire arrays were first investigated by UV/Vis/NIR spectrometer and it was confirmed that the extinction peaks strongly related to the periodicity of the multilayer nanowire. • The Ni segment was thought as a kind of impurity which can change the surface electron distribution and thereby the extinction peaks of nanowire. • Current work supplied the clear layer thickness information of Cu and Ni in Cu/Ni multilayer nanowire with TEM and EDS line-scan profile analysis. - Abstract: For understanding the interaction between light and noble/magnetism multilayer nanowires, Cu/Ni multilayer nanowires are fabricated by a multi-potential step deposition technique in etched ion-track polycarbonate template. The component and the corresponding layer thickness of multilayer nanowire are confirmed by TEM and EDS line-scan analysis. By tailoring the nanowire diameter, the Cu layer thickness and the periodicity of the nanowire, the extinction spectral of nanowire arrays exhibit an extra sensitivity to the change of structural parameters. The resonance wavelength caused by surface plasmon resonance increases obviously with increasing the nanowire diameter, the Cu layer thickness and the periodicity. The observations in our work can be explained by the “impurity effect” and coupled effect and can also be optimized for developing optical devices based on multilayer nanowires.

Control systems using modal domain optical fiber sensors for smart structure applications

Science.gov (United States)

Lindner, Douglas K.; Reichard, Karl M.

1991-01-01

Recently, a new class of sensors has emerged for structural control which respond to environmental changes over a significant gauge length; these sensors are called distributed-effect sensors. These sensors can be fabricated with spatially varying sensitivity to the distributed measurand, and can be configured to measure a variety of structural parameters which can not be measured directly using point sensors. Examples of distributed-effect sensors include piezoelectric film, holographic sensors, and modal domain optical fiber sensors. Optical fiber sensors are particularly attractive for smart structure applications because they are flexible, have low mass, and can easily be embedded directly into materials. In this paper we describe the implementation of weighted modal domain optical fiber sensors. The mathematical model of the modal domain optical fiber sensor model is described and used to derive an expression for the sensor sensitivity. The effects of parameter variations on the sensor sensitivity are demonstrated to illustrate methods of spatially varying the sensor sensitivity.

Recognizing Textual Entailment with Attentive Reading and Writing Operations

DEFF Research Database (Denmark)

Liu, Liang; Huo, Huan; Liu, Xiufeng

2018-01-01

-range dependency. In this paper, we propose to facilitate the conventional attentive reading operations with two sophisticated writing operations - forget and update. Instead of utilizing a single vector that accommodates the attention history, we write the past attention information directly into the sentence...

ENHANCING WRITING SKILL THROUGH WRITING PROCESS APPROACH

Directory of Open Access Journals (Sweden)

M. Zaini Miftah

2015-03-01

Full Text Available The study is aimed at developing the implementation of Writing Process Approach (WPA to enhance the students’ skill in writing essay. The study employed Classroom Action Research. The subjects of the study were 15 university students enrolled in the writing class. The data were gained from writing task, observation and field notes. The findings show that the implementation of WPA with the proper model procedures developed can enhance the students’ skill in writing essay. Before the strategy was implemented, the percentage of the students achieving the score greater than or equal to C (56-70 was 40.00% (6 students of the class. However, after the strategy was implemented in Cycle I, it enhanced enough to 60.00% (9 students of the class, but this result did not meet the criteria of success set up in the study. Next, in Cycle II it increased slightly to 86.67% (13 students of the class. Thus, the enhancement of the students’ skill in writing essay can be reached but it should follow the proper model procedures of the implementation of WPA developed. Keywords: writing process approach, writing skill, essay writing

ENHANCING WRITING SKILL THROUGH WRITING PROCESS APPROACH

OpenAIRE

M. Zaini Miftah

2015-01-01

The study is aimed at developing the implementation of Writing Process Approach (WPA) to enhance the students’ skill in writing essay. The study employed Classroom Action Research. The subjects of the study were 15 university students enrolled in the writing class. The data were gained from writing task, observation and field notes. The findings show that the implementation of WPA with the proper model procedures developed can enhance the students’ skill in writing essay. Before the strategy ...

Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

International Nuclear Information System (INIS)

Chiamenti, Ismael; Costa, Larissa N. da; Kalinowski, Hypolito J.; Bonfigli, Francesca; Montereali, Rosa Maria; Gomes Anderson, S. L.

2014-01-01

Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F 2 and F 3 + color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10 −3 −10 −4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF

Broadband Optical Active Waveguides Written by Femtosecond Laser Pulses in Lithium Fluoride

Science.gov (United States)

Ismael, Chiamenti; Francesca, Bonfigli; Anderson, S. L. Gomes; Rosa, Maria Montereali; Larissa, N. da Costa; Hypolito, J. Kalinowski

2014-01-01

Broadband waveguiding through light-emitting strips directly written in a blank lithium fluoride crystal with a femtosecond laser is reported. Light guiding was observed at several optical wavelengths, from blue, 458 nm, to near-infrared, at 1550 nm. Visible photoluminescence spectra of the optically active F2 and F3+ color centers produced by the fs laser writing process were measured. The wavelength-dependent refractive index increase was estimated to be in the order of 10-3-10-4 in the visible and near-infrared spectral intervals, which is consistent with the stable formation of point defects in LiF.

Solution-processed organic tandem solar cells with embedded optical spacers

NARCIS (Netherlands)

Hadipour, Afshin; de Boer, Bert; Blom, Paul W. M.

2007-01-01

We demonstrate a solution-processed polymer tandem solar cell in which the two photoactive single cells are separated by an optical spacer. The use of an optical spacer allows for an independent optimization of both the electronic and optical properties of the tandem cell. The optical transmission

Directly UV written silica-on-silicon planar waveguides with low insertion loss

DEFF Research Database (Denmark)

Zauner, Dan; Svalgaard, Mikael; Kristensen, Martin

1998-01-01

in waveguide geometry, and excellent control of the refractive index step. Direct UV writing of waveguides became a realistic alternative to other fabrication methods when propagation losses below 0.2 dB/cm were reported in single-mode waveguides. However, the coupling loss to optical fibers remained high......, typically 1.8 dB/facet, which is significantly more than that obtained with other techniques. In this paper we present results in which the coupling loss to optical fibers has been lowered substantially. In addition, the glass photosensitivity has been increased, thus permitting shorter fabrication times......The photosensitive properties of germanosilica may be utilized to directly induce waveguide patterns into thin-film structures using ultraviolet (UV) light. The advantages of fabricating planar waveguides with UV light include the absence of photolithography and reactive ion etching, flexibility...

Direct laser writing of synthetic poly(amino acid) hydrogels and poly(ethylene glycol) diacrylates by two-photon polymerization

Energy Technology Data Exchange (ETDEWEB)

Käpylä, Elli, E-mail: elli.kapyla@tut.fi [Department of Electronics and Communications Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland); BioMediTech, Biokatu 10, 33520 Tampere (Finland); Sedlačík, Tomáš [Institute of Macromolecular Chemistry of the Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 06 Praha 6, Břevnov, Prague (Czech Republic); Aydogan, Dogu Baran [Department of Electronics and Communications Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland); BioMediTech, Biokatu 10, 33520 Tampere (Finland); Viitanen, Jouko [VTT Technical Research Centre of Finland, P.O. Box 1300, 33101 Tampere (Finland); Rypáček, František [Institute of Macromolecular Chemistry of the Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 06 Praha 6, Břevnov, Prague (Czech Republic); Kellomäki, Minna [Department of Electronics and Communications Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland); BioMediTech, Biokatu 10, 33520 Tampere (Finland)

2014-10-01

The additive manufacturing technique of direct laser writing by two-photon polymerization (2PP-DLW) enables the fabrication of three-dimensional microstructures with superior accuracy and flexibility. When combined with biomimetic hydrogel materials, 2PP-DLW can be used to recreate the microarchitectures of the extracellular matrix. However, there are currently only a limited number of hydrogels applicable for 2PP-DLW. In order to widen the selection of synthetic biodegradable hydrogels, in this work we studied the 2PP-DLW of methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s). The performance of these materials was compared to widely used poly(ethylene glycol) diacrylates (PEGdas) in terms of polymerization and damage thresholds, voxel size, line width, post-polymerization swelling and deformation. We found that both methacryloylated and acryloylated poly(AA) hydrogels are suitable to 2PP-DLW with a wider processing window than PEGdas. The poly(AA) with the highest degree of acryloylation showed the greatest potential for 3D microfabrication. - Highlights: • Methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s) were synthesized. • Direct laser writing by two-photon polymerization (2PP-DLW) of poly(AA)s is shown. • Poly(AA)s have wider processing windows than poly(ethylene glycol) diacrylates. • 3D poly(AA) structures with 80% water content were fabricated.

Direct laser writing of synthetic poly(amino acid) hydrogels and poly(ethylene glycol) diacrylates by two-photon polymerization

International Nuclear Information System (INIS)

Käpylä, Elli; Sedlačík, Tomáš; Aydogan, Dogu Baran; Viitanen, Jouko; Rypáček, František; Kellomäki, Minna

2014-01-01

The additive manufacturing technique of direct laser writing by two-photon polymerization (2PP-DLW) enables the fabrication of three-dimensional microstructures with superior accuracy and flexibility. When combined with biomimetic hydrogel materials, 2PP-DLW can be used to recreate the microarchitectures of the extracellular matrix. However, there are currently only a limited number of hydrogels applicable for 2PP-DLW. In order to widen the selection of synthetic biodegradable hydrogels, in this work we studied the 2PP-DLW of methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s). The performance of these materials was compared to widely used poly(ethylene glycol) diacrylates (PEGdas) in terms of polymerization and damage thresholds, voxel size, line width, post-polymerization swelling and deformation. We found that both methacryloylated and acryloylated poly(AA) hydrogels are suitable to 2PP-DLW with a wider processing window than PEGdas. The poly(AA) with the highest degree of acryloylation showed the greatest potential for 3D microfabrication. - Highlights: • Methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s) were synthesized. • Direct laser writing by two-photon polymerization (2PP-DLW) of poly(AA)s is shown. • Poly(AA)s have wider processing windows than poly(ethylene glycol) diacrylates. • 3D poly(AA) structures with 80% water content were fabricated

Optically erasable and rewritable solid-state holograms.

Science.gov (United States)

Gaylord, T. K.; Rabson, T. A.; Tittel, F. K.

1972-01-01

Optical holographic storage in single-crystal LiNbO3 is described which can be optically erased at room temperature and then rewritten with no degradation in efficiency or writing rate. The diffraction efficiencies associated with the process are about 0.0001. Some variations from previously obtained results include a lack of threshold power density for writing, very-long-term persistence of the stored hologram, and a lack of a dependence of the diffracted intensity on the polarization of the readout beam.

Method and apparatus for bistable optical information storage for erasable optical disks

Science.gov (United States)

Land, Cecil E.; McKinney, Ira D.

1990-01-01

A method and an optical device for bistable storage of optical information, together with reading and erasure of the optical information, using a photoactivated shift in a field dependent phase transition between a metastable or a bias-stabilized ferroelectric (FE) phase and a stable antiferroelectric (AFE) phase in an lead lanthanum zirconate titanate (PLZT). An optical disk contains the PLZT. Writing and erasing of optical information can be accomplished by a light beam normal to the disk. Reading of optical information can be accomplished by a light beam at an incidence angle of 15 to 60 degrees to the normal of the disk.

Directed assembly of hybrid nanostructures using optically resonant nanotweezers

Energy Technology Data Exchange (ETDEWEB)

Erickson, David [Cornell Univ., Ithaca, NY (United States)

2015-09-09

This represents the final report for this project. Over the course of the project we have made significant progress in photonically driven nano-assembly including: (1) demonstrating the first direct optical tweezer based manipulation of proteins, (2) the ability to apply optical angular torques to microtubuals and other rod-shaped microparticles, (3) direct assembly of hybrid nanostructures comprising of polymeric nanoparticles and carbon nanotubes and, (4) the ability to drive biological reactions (specifically protein aggregation) that are thermodynamically unfavorable by applying localized optical work. These advancements are described in the list of papers provided in section 2.0 of the below. Summary details are provided in prior year annual reports. We have two additional papers which will be submitted shortly based on the work done under this award. An updated publication list will be provided to the program manager when those are accepted. In this report, we report on a new advancement made in the final project year, which uses the nanotweezer technology to perform direct measurements of particle-surface interactions. Briefly, these measurements are important for characterizing the stability and behavior of colloidal and nanoparticle suspensions and current techniques are limited in their ability to measure piconewton scale interaction forces on sub-micrometer particles due to signal detection limits and thermal noise. In this project year we developed a new technique called “Nanophotonic Force Microscopy” which uses the localized region of exponentially decaying, near-field, light to confine small particles close to a surface. From the statistical distribution of the light intensity scattered by the particle the technique maps out the potential well of the trap and directly quantify the repulsive force between the nanoparticle and the surface. The major advantage of the technique is that it can measure forces and energy wells below the thermal noise

Teaching Science Writing in an Introductory Lab Course

Science.gov (United States)

Holstein, Sarah E.; Mickley Steinmetz, Katherine R.; Miles, John D.

2015-01-01

One challenge that many neuroscience instructors face is how to teach students to communicate within the field. The goal of this project was to improve students’ scientific writing in an introductory psychology laboratory course that serves as a feeder course into the neuroscience curriculum. This course included a scaffolded approach - breaking assignments into different sections that build upon each other to allow for more direction and feedback on each section. Students were also provided with examples of scientific writing, given direction on finding and reading journal articles, and were taught how to effectively peer review a paper. Research papers were assessed before (Year 1) and after (Year 2) this scaffolded approach was instituted. The assessment included measures of “Genre Knowledge” for each section of a research paper (abstract, introduction, method, results, discussion) as well as measures of “Writing Elements” (grammar, formatting, clarity, transitions, building to the hypothesis, using evidence). The results indicated that there was an improvement for Genre Knowledge scores when comparing Year 1 to Year 2. However, there was no systematic improvement in Writing Elements. This suggests that this teaching technique was most effective in improving students’ ability to write within the scientific genre. The logistics of implementing such an approach are discussed. PMID:25838801

'Hopeful' directions for writing centres in South Africa: From safe ...

African Journals Online (AJOL)

Kate H

discuss the theory of the transitional space, which resonates with Delpit's conclusions and which explicitly ... Africa is focused by the memory of the lump of concrete that shattered one of the Wits Writing. Centre windows last ..... racialised culture. Now I think that we must include a focus on the dynamics of racialised power.

Directed Self-Inquiry: A Scaffold for Teaching Laboratory Report Writing

Science.gov (United States)

Deiner, L. Jay; Newsome, Daniel; Samaroo, Diana

2012-01-01

A scaffold was created for the explicit instruction of laboratory report writing. The scaffold breaks the laboratory report into sections and teaches students to ask and answer questions in order to generate section-appropriate content and language. Implementation of the scaffold is done through a series of section-specific worksheets that are…

Embedded NVM technology at BEOL for 14nm FinFET and beyond

Science.gov (United States)

Chi, Min-hwa

2016-10-01

As the FinFET technology is state-of-art CMOS platform at 14nm node and beyond, the embedded non-volatile memory (NVM) technologies need to be fully compatible at front-of-line (FEOL) or back-of-line (BEOL), e.g. Phase-Change-RAM (PCRAM), Resistive-RAM (RRAM), Magnetic-RAM (MRAM), and Nanotube-RAM (NRAM). Each NVM technology at BEOL has its own challenges in program power/energy/speed, thermal stability, read/write stability, endurance, scalability, read/write margins, and degradation by Oxidation, thus, a combination of the NVM technologies at BEOL may offer new applications with capability of stacking-up into 3D array. The CNT-based logic and spin-based logic circuits can be integrated in BEOL and lead to powerful 3D-monolithic integration for new applications with high performance and low power.

Game-Based Practice versus Traditional Practice in Computer-Based Writing Strategy Training: Effects on Motivation and Achievement

Science.gov (United States)

Proske, Antje; Roscoe, Rod D.; McNamara, Danielle S.

2014-01-01

Achieving sustained student engagement with practice in computer-based writing strategy training can be a challenge. One potential solution is to foster engagement by embedding practice in educational games; yet there is currently little research comparing the effectiveness of game-based practice versus more traditional forms of practice. In this…

Real-time capture of student reasoning while writing

Science.gov (United States)

Franklin, Scott V.; Hermsen, Lisa M.

2014-12-01

We present a new approach to investigating student reasoning while writing: real-time capture of the dynamics of the writing process. Key-capture or video software is used to record the entire writing episode, including all pauses, deletions, insertions, and revisions. A succinct shorthand, "S notation," is used to highlight significant moments in the episode that may be indicative of shifts in understanding and can be used in followup interviews for triangulation. The methodology allows one to test the widespread belief that writing is a valuable pedagogical technique, which currently has little directly supportive research. To demonstrate the method, we present a case study of a writing episode. The data reveal an evolution of expression and articulation, discontinuous in both time and space. Distinct shifts in the tone and topic that follow long pauses and revisions are not restricted to the most recently written text. Real-time writing analysis, with its study of the temporal breaks and revision locations, can serve as a complementary tool to more traditional research methods (e.g., speak-aloud interviews) into student reasoning during the writing process.

Sub-10-nm suspended nano-web formation by direct laser writing

Science.gov (United States)

Wang, Sihao; Yu, Ye; Liu, Hailong; Lim, Kevin T. P.; Madurai Srinivasan, Bharathi; Zhang, Yong Wei; Yang, Joel K. W.

2018-06-01

A diffraction-limited three-dimensional (3D) direct laser writing (DLW) system based on two-photon polymerization can routinely pattern structures at the 100 nm length scale. Several schemes have been developed to improve the patterning resolution of 3D DLW but often require customized resist formulations or multi-wavelength exposures. Here, we introduce a scheme to produce suspended nano-webs with feature sizes below 10 nm in IP-Dip resist using sub-threshold exposure conditions in a commercial DLW system. The narrowest suspended lines (nano-webs) measured 7 nm in width. Larger ∼20 nm nano-webs were patterned with ∼80% yield at increased laser powers. In addition, closely spaced nano-gaps with a center-to-center distance of 33 nm were produced by patterning vertically displaced suspended lines followed by metal deposition and liftoff. We provide hypotheses and present preliminary results for a mechanism involving the initiation of a percolative path and a strain-induced narrowing in the nano-web formation. Our approach allows selective features to be patterned with dimensions comparable to the sub-10 nm patterning capability of electron-beam lithography (EBL).

Printing of highly conductive solution by alternating current electrohydrodynamic direct-write

Science.gov (United States)

Jiang, Jiaxin; Zheng, Gaofeng; Wang, Xiang; Zheng, Jianyi; Liu, Juan; Liu, Yifang; Li, Wenwang; Guo, Shumin

2018-03-01

Electrohydrodynamic Direct-Write (EDW) is a novel technology for the printing of micro/nano structures. In this paper, Alternating Current (AC) electrical field was introduced to improve the ejection stability of jet with highly conductive solution. By alternating the electrical field, the polarity of free charges on the surface of jet was changed and the average density of charge, as well as the repulsive force, was reduced to stabilize the jet. When the frequency of AC electrical field increased, the EDW process became more stable and the shape of deposited droplets became more regular. The diameter of printed droplets decreased and the deposition frequency increased with the increase of voltage frequency. The phenomenon of corona discharge was overcome effectively as well. To further evaluate the performance of AC EDW for highly conductive solution, more NaCl was added to the solution and the conductivity was increased to 2810μs/cm. With such high conductivity, the problem of serious corona discharge could still be prevented by AC EDW, and the diameter of printed droplets decreased significantly. This work provides an effective way to accelerate industrial applications of EDW.

Miniaturized and general purpose fiber optic ultrasonic sources

International Nuclear Information System (INIS)

Biagi, E.; Fontani, S.; Masotti, L.; Pieraccini, M.

1997-01-01

Innovative photoacoustic sources for ultrasonic NDE, smart structure, and clinical diagnosis are proposed. The working principle is based on thermal conversion of laser pulses into a metallic film evaporated directly onto the tip of a fiber optic. Unique features of the proposed transducers are very high miniaturization and potential easy embedding in smart structure. Additional advantages, high bedding in smart structure. Additional advantages, high ultrasonic frequency, large and flat bandwidth. All these characteristics make the proposed device an ideal ultrasonic source

Comparing Technologies for Online Writing Conferences: Effects of Medium on Conversation

Science.gov (United States)

Wolfe, Joanna; Griffin, Jo Ann

2012-01-01

This study directly compares face-to-face writing center consultations with two closely related variations of Online Writing Instruction (OWI). Although the study takes place in a busy, dynamic writing center, the authors try to make their comparisons as systematic as possible so they can better foreground some of the benefits and disadvantages of…

A novel sourceline voltage compensation circuit for embedded NOR flash memory

International Nuclear Information System (INIS)

Zhang Shengbo; Yang Guangjun; Hu Jian; Xiao Jun

2014-01-01

A novel sourceline voltage compensation circuit for program operation in embedded flash memory is presented. With the sourceline voltage compensation circuit, the charge pump can modulate the output voltage according to the number of cells to be programmed with data “0”. So the IR drop on the sourceline decoding path is compensated, and a stable sourceline voltage can be obtained. In order to reduce the power dissipation in program operation, a bit-inversion program circuit is adopted. By using the bit-inversion program circuit, the cells programmed to data “0” are limited to half of the bits of a write data word, thus power dissipation in program operation is greatly reduced. A 1.8-V 8 × 64-kbits embedded NOR flash memory employing the two circuits has been integrated using a GSMC 0.18-μm 4-poly 4-metal CMOS process. (semiconductor integrated circuits)

Progress In Optical Memory Technology

Science.gov (United States)

Tsunoda, Yoshito

1987-01-01

More than 20 years have passed since the concept of optical memory was first proposed in 1966. Since then considerable progress has been made in this area together with the creation of completely new markets of optical memory in consumer and computer application areas. The first generation of optical memory was mainly developed with holographic recording technology in late 1960s and early 1970s. Considerable number of developments have been done in both analog and digital memory applications. Unfortunately, these technologies did not meet a chance to be a commercial product. The second generation of optical memory started at the beginning of 1970s with bit by bit recording technology. Read-only type optical memories such as video disks and compact audio disks have extensively investigated. Since laser diodes were first applied to optical video disk read out in 1976, there have been extensive developments of laser diode pick-ups for optical disk memory systems. The third generation of optical memory started in 1978 with bit by bit read/write technology using laser diodes. Developments of recording materials including both write-once and erasable have been actively pursued at several research institutes. These technologies are mainly focused on the optical memory systems for computer application. Such practical applications of optical memory technology has resulted in the creation of such new products as compact audio disks and computer file memories.

Writing learning cases for an information literacy tutorial

Directory of Open Access Journals (Sweden)

Gunhild Austrheim

2010-09-01

Full Text Available The research and writing processes are often hidden mysteries to our students. A key point in the online tutorial Search and Write (Søk and Skriv has been to supply our students with tools to handle these processes. Learning cases embedded in the tutorial allow us to demonstrate a variety of working techniques and to better cater for a diverse student population. The tutorial can be used as an independent resource for students and as a teaching aid for both library sessions on information literacy and for faculty-led sessions on academic writing. Our tutorial is available in Norwegian and in English and thereby the tutorial can be used with both local and international students. An online tutorial is aimed at all students and therefore the information literacy content is of a general kind. The pedagogical foundation for the Search and Write tutorial is in contextual learning. Adding context to our general content has been important to us and we decided to develop learning cases for this purpose. In our online tutorial we have developed three sample student blogs, Kuhlthau’s information search process functions as a template in structuring the students’ stories. The blogs are learning cases, developed with the intent of illustrating various aspects of academic writing tasks. The blog stories are idealized and touch upon many of the known stumbling stones for student writers. Contextualising the search and write process like this let us explore the diversity of student assignments and from various fields of study. When our real-life students use Search and Write they may use their own research question as a point of departure. They can read the blog stories and relate these stories to their own experiences. They can use the How to brainstorm-tips provided in Sofie’s blog. Christian’s use of tutors, library staff and his writing group can provide guidance on who to ask for help. For students writing literature reviews Oda’s systematic

Passionate Writing

DEFF Research Database (Denmark)

Borgström, Benedikte

With care of writing as a method of inquiry, this paper engages in academic writing such as responsible knowledge development drawing on emotion, thought and reason. The aim of the paper is to better understand emancipatory knowledge development. Bodily experiences and responses shape academic...... writing and there are possibilities for responsible academic writing in that iterative process. I propose that academic writing can be seen as possibilities of passionate as well as passive writing....

Optical characterization of luminescent silicon nanocrystals embedded in glass matrices

Energy Technology Data Exchange (ETDEWEB)

Debieu, Olivier

2008-12-16

properties of embedded nc-Si. Proceeding to Ge implantation, we are convinced to synthesize for the first time luminescent alloy nc-Si{sub 1-x}Ge{sub x} with this technique. Taking into account this result, one can reasonably put forward the assumption that not only pure nc-Si can exhibit PL. Chapter 4 deals with the optical and structural properties of free O-passivated nc-Si and nc-Si/SiO{sub 2} systems synthesized by laser pyrolysis of silane and ion implantation, respectively. We were particularly interested in the formation nc-Si/SiO{sub 2} systems and their PL properties, the purpose of which is to obtain efficient luminescent samples into which additional atomic elements will be incorporated. In the last chapter, we focus on the effect of the incorporation of additional atomic elements into our nc-Si/SiO{sub 2} systems on their optical properties. Motivated by the desire to synthesize luminescent alloy nc-Si{sub 1} {sub -x}Ge{sub x}, we also applied our incorporation procedure to Ge.

The technical writer's handbook writing with style and clarity

CERN Document Server

Young, Matt

2002-01-01

"The Technical Writer's Handbook" is by a practising scientist who screens hundreds of manuscripts each year. It is directed at scientists, engineers and others who want to improve their writing and communication. It teaches that technical writing, although it has its own special requirements, is no different from ordinary writing and should be written with short, clear sentences and in the active voice. Divided into two parts, the first part is an introduction to technical and report writing and provides a sort of prescription for writing and organizing technical papers of all kinds. The second part is written in dictionary format and contains entries on grammar, style, and organization, as well as entries on topics such as common errors, resume writing, metric units, jargon, conference proceedings, figures, tables and slides. A comprehensive list of cross-references reveals related topics quickly and easily.

Design and test of a novel accelerometer made-up of an optical-fiber embedded within a polymer resin

Directory of Open Access Journals (Sweden)

Tihon Pierre

2015-01-01

Full Text Available This paper presents a transducer for an optical-fiber accelerometer based on a polarization analysis. The transducer is made up of a fiber section embedded within a resin placed between two metallic pieces. Due to the acceleration, the resin is crushed between the metallic pieces, deforming the fiber section and inducing birefringence in the latter. This birefringence modifies the light polarization state, which can be used as an acceleration measurement. The sensor characteristics (sensitivity and resonance frequency are numerically and experimentally determined. Sine accelerations at 120 Hz with amplitudes going from 5 m/s2 to 13 m/s2 have been successfully measured. The resonance frequency for the transducer crushing mode is above 5000 Hz, but low-frequency vibration modes exist, disturbing the measurements.

Embedded Hyperchaotic Generators: A Comparative Analysis

Science.gov (United States)

Sadoudi, Said; Tanougast, Camel; Azzaz, Mohamad Salah; Dandache, Abbas

In this paper, we present a comparative analysis of FPGA implementation performances, in terms of throughput and resources cost, of five well known autonomous continuous hyperchaotic systems. The goal of this analysis is to identify the embedded hyperchaotic generator which leads to designs with small logic area cost, satisfactory throughput rates, low power consumption and low latency required for embedded applications such as secure digital communications between embedded systems. To implement the four-dimensional (4D) chaotic systems, we use a new structural hardware architecture based on direct VHDL description of the forth order Runge-Kutta method (RK-4). The comparative analysis shows that the hyperchaotic Lorenz generator provides attractive performances compared to that of others. In fact, its hardware implementation requires only 2067 CLB-slices, 36 multipliers and no block RAMs, and achieves a throughput rate of 101.6 Mbps, at the output of the FPGA circuit, at a clock frequency of 25.315 MHz with a low latency time of 316 ns. Consequently, these good implementation performances offer to the embedded hyperchaotic Lorenz generator the advantage of being the best candidate for embedded communications applications.

Embedded Volttron specification - benchmarking small footprint compute device for Volttron

Energy Technology Data Exchange (ETDEWEB)

Sanyal, Jibonananda [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fugate, David L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Woodworth, Ken [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nutaro, James J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuruganti, Teja [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-08-17

An embedded system is a small footprint computing unit that typically serves a specific purpose closely associated with measurements and control of hardware devices. These units are designed for reasonable durability and operations in a wide range of operating conditions. Some embedded systems support real-time operations and can demonstrate high levels of reliability. Many have failsafe mechanisms built to handle graceful shutdown of the device in exception conditions. The available memory, processing power, and network connectivity of these devices are limited due to the nature of their specific-purpose design and intended application. Industry practice is to carefully design the software for the available hardware capability to suit desired deployment needs. Volttron is an open source agent development and deployment platform designed to enable researchers to interact with devices and appliances without having to write drivers themselves. Hosting Volttron on small footprint embeddable devices enables its demonstration for embedded use. This report details the steps required and the experience in setting up and running Volttron applications on three small footprint devices: the Intel Next Unit of Computing (NUC), the Raspberry Pi 2, and the BeagleBone Black. In addition, the report also details preliminary investigation of the execution performance of Volttron on these devices.

Embedded system of image storage based on fiber channel

Science.gov (United States)

Chen, Xiaodong; Su, Wanxin; Xing, Zhongbao; Wang, Hualong

2008-03-01

In domains of aerospace, aviation, aiming, and optic measure etc., the embedded system of imaging, processing and recording is absolutely necessary, which has small volume, high processing speed and high resolution. But the embedded storage technology becomes system bottleneck because of developing slowly. It is used to use RAID to promote storage speed, but it is unsuitable for the embedded system because of its big volume. Fiber channel (FC) technology offers a new method to develop the high-speed, portable storage system. In order to make storage subsystem meet the needs of high storage rate, make use of powerful Virtex-4 FPGA and high speed fiber channel, advance a project of embedded system of digital image storage based on Xilinx Fiber Channel Arbitrated Loop LogiCORE. This project utilizes Virtex- 4 RocketIO MGT transceivers to transmit the data serially, and connects many Fiber Channel hard drivers by using of Arbitrated Loop optionally. It can achieve 400MBps storage rate, breaks through the bottleneck of PCI interface, and has excellences of high-speed, real-time, portable and massive capacity.

Electro-mechanical control of an on-chip optical beam splitter containing an embedded quantum emitter.

Science.gov (United States)

Bishop, Z K; Foster, A P; Royall, B; Bentham, C; Clarke, E; Skolnick, M S; Wilson, L R

2018-05-01

We demonstrate electro-mechanical control of an on-chip GaAs optical beam splitter containing a quantum dot single-photon source. The beam splitter consists of two nanobeam waveguides, which form a directional coupler (DC). The splitting ratio of the DC is controlled by varying the out-of-plane separation of the two waveguides using electromechanical actuation. We reversibly tune the beam splitter between an initial state, with emission into both output arms, and a final state with photons emitted into a single output arm. The device represents a compact and scalable tuning approach for use in III-V semiconductor integrated quantum optical circuits.

Electro-mechanical control of an on-chip optical beam splitter containing an embedded quantum emitter

Science.gov (United States)

Bishop, Z. K.; Foster, A. P.; Royall, B.; Bentham, C.; Clarke, E.; Skolnick, M. S.; Wilson, L. R.

2018-05-01

We demonstrate electro-mechanical control of an on-chip GaAs optical beam splitter containing a quantum dot single-photon source. The beam splitter consists of two nanobeam waveguides, which form a directional coupler (DC). The splitting ratio of the DC is controlled by varying the out-of-plane separation of the two waveguides using electro-mechanical actuation. We reversibly tune the beam splitter between an initial state, with emission into both output arms, and a final state with photons emitted into a single output arm. The device represents a compact and scalable tuning approach for use in III-V semiconductor integrated quantum optical circuits.

Direct writing of gold nanostructures with an electron beam: On the way to pure nanostructures by combining optimized deposition with oxygen-plasma treatment

Directory of Open Access Journals (Sweden)

Domagoj Belić

2017-11-01

Full Text Available This work presents a highly effective approach for the chemical purification of directly written 2D and 3D gold nanostructures suitable for plasmonics, biomolecule immobilisation, and nanoelectronics. Gold nano- and microstructures can be fabricated by one-step direct-write lithography process using focused electron beam induced deposition (FEBID. Typically, as-deposited gold nanostructures suffer from a low Au content and unacceptably high carbon contamination. We show that the undesirable carbon contamination can be diminished using a two-step process – a combination of optimized deposition followed by appropriate postdeposition cleaning. Starting from the common metal-organic precursor Me2-Au-tfac, it is demonstrated that the Au content in pristine FEBID nanostructures can be increased from 30 atom % to as much as 72 atom %, depending on the sustained electron beam dose. As a second step, oxygen-plasma treatment is established to further enhance the Au content in the structures, while preserving their morphology to a high degree. This two-step process represents a simple, feasible and high-throughput method for direct writing of purer gold nanostructures that can enable their future use for demanding applications.

Exact solutions for isometric embeddings of pseudo-Riemannian manifolds

International Nuclear Information System (INIS)

Amery, G; Moodley, J

2014-01-01

Embeddings into higher dimensions are of direct importance in the study of higher dimensional theories of our Universe, in high energy physics and in classical general relativity. Theorems have been established that guarantee the existence of local and global codimension-1 embeddings between pseudo-Riemannian manifolds, particularly for Einstein embedding spaces. A technique has been provided to determine solutions to such embeddings. However, general solutions have not yet been found and most known explicit solutions are for embedded spaces with relatively simple Ricci curvature. Motivated by this, we have considered isometric embeddings of 4-dimensional pseudo-Riemannian spacetimes into 5-dimensional Einstein manifolds. We have applied the technique to treat specific 4-dimensional cases of interest in astrophysics and cosmology (including the global monopole exterior and Vaidya-de Sitter-class solutions), and provided novel physical insights into, for example, Einstein-Gauss-Bonnet gravity. Since difficulties arise in solving the 5-dimensional equations for given 4-dimensional spaces, we have also investigated embedded spaces, which admit bulks with a particular metric form. These analyses help to provide insight to the general embedding problem

Researching into a MOOC Embedded Flipped Classroom Model for College English Reading and Writing Course

Science.gov (United States)

Xinying, Zhang

2017-01-01

There is obvious pressure for higher education institutions to undergo transformation now in China. Reflecting this, the computer and information technology give rise to the development of a Massive Open Online Course (MOOC) embedded flipped classroom. Flipped classroom approaches replace the traditional transmissive teaching with engaging…

Demonstration and Methodology of Structural Monitoring of Stringer Runs out Composite Areas by Embedded Optical Fiber Sensors and Connectors Integrated during Production in a Composite Plant.

Science.gov (United States)

Miguel Giraldo, Carlos; Zúñiga Sagredo, Juan; Sánchez Gómez, José; Corredera, Pedro

2017-07-21

Embedding optical fibers sensors into composite structures for Structural Health Monitoring purposes is not just one of the most attractive solutions contributing to smart structures, but also the optimum integration approach that insures maximum protection and integrity of the fibers. Nevertheless this intended integration level still remains an industrial challenge since today there is no mature integration process in composite plants matching all necessary requirements. This article describes the process developed to integrate optical fiber sensors in the Production cycle of a test specimen. The sensors, Bragg gratings, were integrated into the laminate during automatic tape lay-up and also by a secondary bonding process, both in the Airbus Composite Plant. The test specimen, completely representative of the root joint of the lower wing cover of a real aircraft, is comprised of a structural skin panel with the associated stringer run out. The ingress-egress was achieved through the precise design and integration of miniaturized optical connectors compatible with the manufacturing conditions and operational test requirements. After production, the specimen was trimmed, assembled and bolted to metallic plates to represent the real triform and buttstrap, and eventually installed into the structural test rig. The interrogation of the sensors proves the effectiveness of the integration process; the analysis of the strain results demonstrate the good correlation between fiber sensors and electrical gauges in those locations where they are installed nearby, and the curvature and load transfer analysis in the bolted stringer run out area enable demonstration of the consistency of the fiber sensors measurements. In conclusion, this work presents strong evidence of the performance of embedded optical sensors for structural health monitoring purposes, where in addition and most importantly, the fibers were integrated in a real production environment and the ingress

Writing by the Book, Writing beyond the Book

Science.gov (United States)

Johnson, Kristine

2017-01-01

Writing has become more visible in academia through writing advice manuals and the faculty development activities they inspire. In this article, I examine writing advice manuals and argue they are epistemologically current traditional, which limits how well and how far they can support scholarly writers. Writing advice manuals and composition…

Embedded Leverage

DEFF Research Database (Denmark)

Frazzini, Andrea; Heje Pedersen, Lasse

find that asset classes with embedded leverage offer low risk-adjusted returns and, in the cross-section, higher embedded leverage is associated with lower returns. A portfolio which is long low-embedded-leverage securities and short high-embedded-leverage securities earns large abnormal returns...

Experiences as an embedded librarian in online courses.

Science.gov (United States)

Konieczny, Alison

2010-01-01

Embedded librarianship gives librarians a prime opportunity to have a direct, positive impact in a clinical setting, classroom setting, or within a working group by providing integrated services that cater to the group's needs. Extending embedded librarian services beyond the various physical settings and into online classrooms is an exceptional way for librarians to engage online learners. This group of students is growing rapidly in numbers and could benefit greatly from having library services and resources incorporated into their classes. The author's services as an embedded librarian in fully online courses at a medium-sized university will be discussed, as will strategies, lessons learned, and opportunities for engaging in this realm. To develop a foundation of knowledge on embedded librarianship, an overview of this topic is provided.

Quantum optics with quantum dots in photonic nanowires

DEFF Research Database (Denmark)

We will review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices.......We will review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices....

Photoinduced transformations of optical properties of CdSe and Ag-In-S nanocrystals embedded in the films of polyvinyl alcohol

Directory of Open Access Journals (Sweden)

Tetyana Kryshtab

2016-06-01

Full Text Available The results of investigation of photostability of the composites of CdSe and Ag-In-S nanocrystals (NCs embedded in the films of polyvinyl alcohol (PVA are presented. The films were studied by photoluminescence (PL, optical absorption, micro-Raman and X-ray diffraction methods. It is found that heating of the films to 100 °C promotes PVA crystallization and stimulates an increase of the PL intensity for the NCs of both types. The latter effect is ascribed mainly to the improvement of NC surface passivation by functional groups of PVA. The illumination with the 409-nm LED’s light enhances PL intensity for CdSe NCs and decreases it for Ag-In-S NCs as well as results in the darkening of the films. The color of the Ag-In-S-PVA film restores with time, while the change of the optical properties of the CdSe-PVA composite is irreversible. The possible mechanisms of the revealed effects, such as structural transformations at NC/PVA interface as well as the formation of new light-absorbing species are discussed.

Embedding potentials for excited states of embedded species

International Nuclear Information System (INIS)

Wesolowski, Tomasz A.

2014-01-01

Frozen-Density-Embedding Theory (FDET) is a formalism to obtain the upper bound of the ground-state energy of the total system and the corresponding embedded wavefunction by means of Euler-Lagrange equations [T. A. Wesolowski, Phys. Rev. A 77(1), 012504 (2008)]. FDET provides the expression for the embedding potential as a functional of the electron density of the embedded species, electron density of the environment, and the field generated by other charges in the environment. Under certain conditions, FDET leads to the exact ground-state energy and density of the whole system. Following Perdew-Levy theorem on stationary states of the ground-state energy functional, the other-than-ground-state stationary states of the FDET energy functional correspond to excited states. In the present work, we analyze such use of other-than-ground-state embedded wavefunctions obtained in practical calculations, i.e., when the FDET embedding potential is approximated. Three computational approaches based on FDET, that assure self-consistent excitation energy and embedded wavefunction dealing with the issue of orthogonality of embedded wavefunctions for different states in a different manner, are proposed and discussed

Optically resonant magneto-electric cubic nanoantennas for ultra-directional light scattering

Energy Technology Data Exchange (ETDEWEB)

Sikdar, Debabrata, E-mail: debabrata.sikdar@monash.edu; Premaratne, Malin [Advanced Computing and Simulation Laboratory (A chi L), Department of Electrical and Computer Systems Engineering, Monash University, Clayton 3800, Victoria (Australia); Cheng, Wenlong [Department of Chemical Engineering, Faculty of Engineering, Monash University, Clayton 3800, Victoria (Australia); The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton 3168, Victoria (Australia)

2015-02-28

Cubic dielectric nanoparticles are promising candidates for futuristic low-loss, ultra-compact, nanophotonic applications owing to their larger optical coefficients, greater packing density, and relative ease of fabrication as compared to spherical nanoparticles; besides possessing negligible heating at nanoscale in contrast to their metallic counterparts. Here, we present the first theoretical demonstration of azimuthally symmetric, ultra-directional Kerker's-type scattering of simple dielectric nanocubes in visible and near-infrared regions via simultaneous excitation and interference of optically induced electric- and magnetic-resonances up to quadrupolar modes. Unidirectional forward-scattering by individual nanocubes is observed at the first generalized-Kerker's condition for backward-scattering suppression, having equal electric- and magnetic-dipolar responses. Both directionality and magnitude of these unidirectional-scattering patterns get enhanced where matching electric- and magnetic-quadrupolar responses spectrally overlap. While preserving azimuthal-symmetry and backscattering suppression, a nanocube homodimer provides further directionality improvement for increasing interparticle gap, but with reduced main-lobe magnitude due to emergence of side-scattering lobes from diffraction-grating effect. We thoroughly investigate the influence of interparticle gap on scattering patterns and propose optimal range of gap for minimizing side-scattering lobes. Besides suppressing undesired side-lobes, significant enhancement in scattering magnitude and directionality is attained with increasing number of nanocubes forming a linear chain. Optimal directionality, i.e., the narrowest main-scattering lobe, is found at the wavelength of interfering quadrupolar resonances; whereas the largest main-lobe magnitude is observed at the wavelength satisfying the first Kerker's condition. These unique optical properties of dielectric nanocubes thus can

Kodak phase-change media for optical tape applications

Science.gov (United States)

Tyan, Yuan-Sheng; Preuss, Donald R.; Olin, George R.; Vazan, Fridrich; Pan, Kee-Chuan; Raychaudhuri, Pranab. K.

1993-01-01

The SbInSn phase-change write-once optical medium developed by Eastman Kodak Company is particularly suitable for development into the next generation optical tape media. Its performance for optical recording has already been demonstrated in some of the highest performance optical disk systems. Some of the key performance features are presented.

Hybrid fabrication process of additive manufacturing and direct writing for a 4 X 4 mm matrix flexible tactile sensor

Energy Technology Data Exchange (ETDEWEB)

Woo, Sang Gu; Lee, In Hwan [Chungbuk National University, Chungju (Korea, Republic of); Lee, Kyong Chang [Pukyong National University, Busan (Korea, Republic of)

2015-09-15

Various machines require data from their external environments for safety and/or accuracy. In this respect, many sensors that mimic the human sensory system have been investigated. Among these, tactile sensors may be useful for obtaining data on the roughness of, and external forces acting upon, an object. Several tactile sensors have been developed; however, these are typically fabricated via a series of complex processes, and hence are unsuitable for volume manufacturing. In this paper, we report a fabrication process for a 4 X 4 mm matrix flexible sensor element using layered manufacturing and direct-write technology. A composite composed of photocurable resin and Multi-walled carbon nanotubes (MWCNTs) was used as the sensing material. The MWCNTs were mixed with the photocurable resin using ultrasonic dispersion, and the liquid mixture exhibited excellent piezoresistive properties following curing using ultraviolet light. The used photocurable resin is flexible and elastic after curing. Therefore, the composite material can be bent and deformed. To use this composite material with the flexible sensor, dispensing characteristics were examined using direct-write technology. For the acquisition of sensor data, a commercial pin-header was inserted and photocurable resin was filled up to the height of pin-header and cured . Then, the composite material was dispensed onto the pin-header as a sensing material. Using this process, a flexible sensor with piezoresistive properties was formed.

Hybrid fabrication process of additive manufacturing and direct writing for a 4 X 4 mm matrix flexible tactile sensor

International Nuclear Information System (INIS)

Woo, Sang Gu; Lee, In Hwan; Lee, Kyong Chang

2015-01-01

Various machines require data from their external environments for safety and/or accuracy. In this respect, many sensors that mimic the human sensory system have been investigated. Among these, tactile sensors may be useful for obtaining data on the roughness of, and external forces acting upon, an object. Several tactile sensors have been developed; however, these are typically fabricated via a series of complex processes, and hence are unsuitable for volume manufacturing. In this paper, we report a fabrication process for a 4 X 4 mm matrix flexible sensor element using layered manufacturing and direct-write technology. A composite composed of photocurable resin and Multi-walled carbon nanotubes (MWCNTs) was used as the sensing material. The MWCNTs were mixed with the photocurable resin using ultrasonic dispersion, and the liquid mixture exhibited excellent piezoresistive properties following curing using ultraviolet light. The used photocurable resin is flexible and elastic after curing. Therefore, the composite material can be bent and deformed. To use this composite material with the flexible sensor, dispensing characteristics were examined using direct-write technology. For the acquisition of sensor data, a commercial pin-header was inserted and photocurable resin was filled up to the height of pin-header and cured . Then, the composite material was dispensed onto the pin-header as a sensing material. Using this process, a flexible sensor with piezoresistive properties was formed.

Detailed noise statistics for an optically preamplified direct detection receiver

DEFF Research Database (Denmark)

Danielsen, Søren Lykke; Mikkelsen, Benny; Durhuus, Terji

1995-01-01

We describe the exact statistics of an optically preamplified direct detection receiver by means of the moment generating function. The theory allows an arbitrary shaped electrical filter in the receiver circuit. The moment generating function (MGF) allows for a precise calculation of the error...... rate by using the inverse Fast Fourier transform (FFT). The exact results are compared with the usual Gaussian approximation (GA), the saddlepoint approximation (SAP) and the modified Chernoff bound (MCB). This comparison shows that the noise is not Gaussian distributed for all values of the optical...... and calculate the sensitivity degradation due to inter symbol interference (ISI)...

Real-time capture of student reasoning while writing

Directory of Open Access Journals (Sweden)

Scott V. Franklin

2014-09-01

Full Text Available We present a new approach to investigating student reasoning while writing: real-time capture of the dynamics of the writing process. Key-capture or video software is used to record the entire writing episode, including all pauses, deletions, insertions, and revisions. A succinct shorthand, “S notation,” is used to highlight significant moments in the episode that may be indicative of shifts in understanding and can be used in followup interviews for triangulation. The methodology allows one to test the widespread belief that writing is a valuable pedagogical technique, which currently has little directly supportive research. To demonstrate the method, we present a case study of a writing episode. The data reveal an evolution of expression and articulation, discontinuous in both time and space. Distinct shifts in the tone and topic that follow long pauses and revisions are not restricted to the most recently written text. Real-time writing analysis, with its study of the temporal breaks and revision locations, can serve as a complementary tool to more traditional research methods (e.g., speak-aloud interviews into student reasoning during the writing process.

Technical writing versus technical writing

Science.gov (United States)

Dillingham, J. W.

1981-01-01

Two terms, two job categories, 'technical writer' and 'technical author' are discussed in terms of industrial and business requirements and standards. A distinction between 'technical writing' and technical 'writing' is made. The term 'technical editor' is also considered. Problems inherent in the design of programs to prepare and train students for these jobs are discussed. A closer alliance between industry and academia is suggested as a means of preparing students with competent technical communication skills (especially writing and editing skills) and good technical skills.

Relevant optical properties for direct restorative materials.

Science.gov (United States)

Pecho, Oscar E; Ghinea, Razvan; do Amaral, Erika A Navarro; Cardona, Juan C; Della Bona, Alvaro; Pérez, María M

2016-05-01

To evaluate relevant optical properties of esthetic direct restorative materials focusing on whitened and translucent shades. Enamel (E), body (B), dentin (D), translucent (T) and whitened (Wh) shades for E (WhE) and B (WhB) from a restorative system (Filtek Supreme XTE, 3M ESPE) were evaluated. Samples (1 mm thick) were prepared. Spectral reflectance (R%) and color coordinates (L*, a*, b*, C* and h°) were measured against black and white backgrounds, using a spectroradiometer, in a viewing booth, with CIE D65 illuminant and d/0° geometry. Scattering (S) and absorption (K) coefficients and transmittance (T%) were calculated using Kubelka-Munk's equations. Translucency (TP) and opalescence (OP) parameters and whiteness index (W*) were obtained from differences of CIELAB color coordinates. R%, S, K and T% curves from all shades were compared using VAF (Variance Accounting For) coefficient with Cauchy-Schwarz inequality. Color coordinates and optical parameters were statistically analyzed using one-way ANOVA, Tukey's test with Bonferroni correction (α=0.0007). Spectral behavior of R% and S were different for T shades. In addition, T shades showed the lowest R%, S and K values, as well as the highest T%, TP an OP values. In most cases, WhB shades showed different color and optical properties (including TP and W*) than their corresponding B shades. WhE shades showed similar mean W* values and higher mean T% and TP values than E shades. When using whitened or translucent composites, the final color is influenced not only by the intraoral background but also by the color and optical properties of multilayers used in the esthetic restoration. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Career Directions--Fiber Optic Installer

Science.gov (United States)

Tech Directions, 2012

2012-01-01

Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber that is roughly the diameter of a human hair. The light forms an electromagnetic carrier wave that is modulated to carry information. Each optical fiber is capable of carrying an enormous amount of…

Improving Understanding in Ordinary Differential Equations through Writing in a Dynamical Environment

Science.gov (United States)

Habre, Samer

2012-01-01

Research on writing in mathematics has shown that students learn more effectively in an environment that promotes this skill and that writing is most beneficial when it is directed at the learning aspect. Writing, however, necessitates proficiency on the part of the students that may not have been developed at earlier learning stages. Research has…

Students’ Problems in Writing Paraphrases in Research Paper Writing Class

Directory of Open Access Journals (Sweden)

Herdiansari Hayuningrum

2017-01-01

Full Text Available Paraphrase is one of the techniques of incorporating sources in which every writer is allowed to borrow the author’s ideas and restate them into their own words. Based on the previous study, it was found that English Language Education Study Program (ELESP students, Sanata Dharma University, were unable to paraphrase properly since they tended to copy the author’s words directly. If this problem was continuously ignored, it would be dangerous for the students because they could be charged with inadvertent plagiarism. This study was intended to investigate ELESP students’ problems in writing paraphrases and the reasons why they produce unacceptable paraphrases by conducting document analysis and interview in Research Paper Writing class. From the findings, it could be identified that the most frequent type of problem encountered by the students was word-for-word plagiarism.   DOI: https://doi.org/10.24071/llt.2012.150101

Integrating Fiber Optic Strain Sensors into Metal Using Ultrasonic Additive Manufacturing

Science.gov (United States)

Hehr, Adam; Norfolk, Mark; Wenning, Justin; Sheridan, John; Leser, Paul; Leser, Patrick; Newman, John A.

2018-03-01

Ultrasonic additive manufacturing, a rather new three-dimensional (3D) printing technology, uses ultrasonic energy to produce metallurgical bonds between layers of metal foils near room temperature. This low temperature attribute of the process enables integration of temperature sensitive components, such as fiber optic strain sensors, directly into metal structures. This may be an enabling technology for Digital Twin applications, i.e., virtual model interaction and feedback with live load data. This study evaluates the consolidation quality, interface robustness, and load sensing limits of commercially available fiber optic strain sensors embedded into aluminum alloy 6061. Lastly, an outlook on the technology and its applications is described.

Stop. Write! Writing Grounded Theory

Directory of Open Access Journals (Sweden)

Barney G. Glaser, PhD, Hon. PhD

2012-06-01

Full Text Available The message in this book, the dictum in this book, is to stop and write when the Grounded Theory (GT methodology puts you in that ready position. Stop unending conceptualization, unending data coverage, and unending listening to others who would egg you on with additional data, ideas and/or requirements or simply wait too long. I will discuss these ideas in detail. My experience with PhD candidates is that for the few who write when ready, many do not and SHOULD. Simply put, many write-up, but many more should.

Writing Workshop.

Science.gov (United States)

Novelli, Joan

2001-01-01

Six ideas for writing autobiographies with elementary school students include: model the writing process to get students started; read examples of autobiographies; brainstorm writing ideas; free-write the first draft; edit and revise; and publish the stories. Suggestions for mini-lessons are included. A student reproducible offers an editing…

Hard real-time multibody simulations using ARM-based embedded systems

Energy Technology Data Exchange (ETDEWEB)

Pastorino, Roland, E-mail: roland.pastorino@kuleuven.be, E-mail: rpastorino@udc.es; Cosco, Francesco, E-mail: francesco.cosco@kuleuven.be; Naets, Frank, E-mail: frank.naets@kuleuven.be; Desmet, Wim, E-mail: wim.desmet@kuleuven.be [KU Leuven, PMA division, Department of Mechanical Engineering (Belgium); Cuadrado, Javier, E-mail: javicuad@cdf.udc.es [Universidad de La Coruña, Laboratorio de Ingeniería Mecánica (Spain)

2016-05-15

The real-time simulation of multibody models on embedded systems is of particular interest for controllers and observers such as model predictive controllers and state observers, which rely on a dynamic model of the process and are customarily executed in electronic control units. This work first identifies the software techniques and tools required to easily write efficient code for multibody models to be simulated on ARM-based embedded systems. Automatic Programming and Source Code Translation are the two techniques that were chosen to generate source code for multibody models in different programming languages. Automatic Programming is used to generate procedural code in an intermediate representation from an object-oriented library and Source Code Translation is used to translate the intermediate representation automatically to an interpreted language or to a compiled language for efficiency purposes. An implementation of these techniques is proposed. It is based on a Python template engine and AST tree walkers for Source Code Generation and on a model-driven translator for the Source Code Translation. The code is translated from a metalanguage to any of the following four programming languages: Python-Numpy, Matlab, C++-Armadillo, C++-Eigen. Two examples of multibody models were simulated: a four-bar linkage with multiple loops and a 3D vehicle steering system. The code for these examples has been generated and executed on two ARM-based single-board computers. Using compiled languages, both models could be simulated faster than real-time despite the low resources and performance of these embedded systems. Finally, the real-time performance of both models was evaluated when executed in hard real-time on Xenomai for both embedded systems. This work shows through measurements that Automatic Programming and Source Code Translation are valuable techniques to develop real-time multibody models to be used in embedded observers and controllers.

Hard real-time multibody simulations using ARM-based embedded systems

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