Science.gov

Sample records for additional fabrication steps

  1. Additives in fibers and fabrics.

    PubMed

    Barker, R H

    1975-06-01

    The additives and contaminants which occur in textile fibers vary widely, depending on the type of fiber and the pretreatment which it has received. Synthetic fibers such as nylon and polyester contain trace amounts of contaminants such as catalysts and catalyst deactivators which remain after the synthesis of the basic polymers. In addition, there are frequently a number of materials which are added to perform specific functions in almost all man-made fibers. Examples of these would include traces of metals or metal salts used as tracers for identification of specific lots of fiber, TiO2 or similar materials added as delustrants, and a host of organic species added for such special purposes as antistatic agents or flame retardants. There may also be considerable quantities of residual monomer or small oligomers dissolved in the polymer matrix. The situation becomes even more complex after the fibers are converted into fabric form. Numerous materials are applied at various stages of fabric preparation to act as lubricants, sizing agents, antistats, bleaches, and wetting agents to facilitate the processing, but these are normally removed before the fabric reaches the cutters of the ultimate consumers and therefore usually do not constitute potential hazards. However, there are many other chemical agents which are frequently added during the later stages of fabric preparation and which are not designed to be removed. Aside from dyes and printing pigments, the most common additive for apparel fabrics is a durable press treatment. This generally involves the use of materials capable of crosslinking cellulosics by reacting through such functions as N-methylolated amides or related compounds such as ureas and carbamates. These materials pose some potential hazards due to both the nitrogenous bases and the formaldehyde which they usually release. There is usually also some residual catalyst in fabrics which have received such treatments. Other types of chemical treatments

  2. Additives in fibers and fabrics.

    PubMed Central

    Barker, R H

    1975-01-01

    The additives and contaminants which occur in textile fibers vary widely, depending on the type of fiber and the pretreatment which it has received. Synthetic fibers such as nylon and polyester contain trace amounts of contaminants such as catalysts and catalyst deactivators which remain after the synthesis of the basic polymers. In addition, there are frequently a number of materials which are added to perform specific functions in almost all man-made fibers. Examples of these would include traces of metals or metal salts used as tracers for identification of specific lots of fiber, TiO2 or similar materials added as delustrants, and a host of organic species added for such special purposes as antistatic agents or flame retardants. There may also be considerable quantities of residual monomer or small oligomers dissolved in the polymer matrix. The situation becomes even more complex after the fibers are converted into fabric form. Numerous materials are applied at various stages of fabric preparation to act as lubricants, sizing agents, antistats, bleaches, and wetting agents to facilitate the processing, but these are normally removed before the fabric reaches the cutters of the ultimate consumers and therefore usually do not constitute potential hazards. However, there are many other chemical agents which are frequently added during the later stages of fabric preparation and which are not designed to be removed. Aside from dyes and printing pigments, the most common additive for apparel fabrics is a durable press treatment. This generally involves the use of materials capable of crosslinking cellulosics by reacting through such functions as N-methylolated amides or related compounds such as ureas and carbamates. These materials pose some potential hazards due to both the nitrogenous bases and the formaldehyde which they usually release. There is usually also some residual catalyst in fabrics which have received such treatments. Other types of chemical treatments

  3. One-step fabrication of multifunctional micromotors

    NASA Astrophysics Data System (ADS)

    Gao, Wenlong; Liu, Mei; Liu, Limei; Zhang, Hui; Dong, Bin; Li, Christopher Y.

    2015-08-01

    Although artificial micromotors have undergone tremendous progress in recent years, their fabrication normally requires complex steps or expensive equipment. In this paper, we report a facile one-step method based on an emulsion solvent evaporation process to fabricate multifunctional micromotors. By simultaneously incorporating various components into an oil-in-water droplet, upon emulsification and solidification, a sphere-shaped, asymmetric, and multifunctional micromotor is formed. Some of the attractive functions of this model micromotor include autonomous movement in high ionic strength solution, remote control, enzymatic disassembly and sustained release. This one-step, versatile fabrication method can be easily scaled up and therefore may have great potential in mass production of multifunctional micromotors for a wide range of practical applications.Although artificial micromotors have undergone tremendous progress in recent years, their fabrication normally requires complex steps or expensive equipment. In this paper, we report a facile one-step method based on an emulsion solvent evaporation process to fabricate multifunctional micromotors. By simultaneously incorporating various components into an oil-in-water droplet, upon emulsification and solidification, a sphere-shaped, asymmetric, and multifunctional micromotor is formed. Some of the attractive functions of this model micromotor include autonomous movement in high ionic strength solution, remote control, enzymatic disassembly and sustained release. This one-step, versatile fabrication method can be easily scaled up and therefore may have great potential in mass production of multifunctional micromotors for a wide range of practical applications. Electronic supplementary information (ESI) available: Videos S1-S4 and Fig. S1-S3. See DOI: 10.1039/c5nr03574k

  4. Fabrication of (Co,Mn)3O4/rGO Composite for Lithium Ion Battery Anode by a One-Step Hydrothermal Process with H2O2 as Additive

    PubMed Central

    Li, Zuohua; Cui, Yanhui; Chen, Jun; Deng, Lianlin

    2016-01-01

    Binary transition metal oxides have been regarded as one of the most promising candidates for high-performance electrodes in energy storage devices, since they can offer high electrochemical activity and high capacity. Rational designing nanosized metal oxide/carbon composite architectures has been proven to be an effective way to improve the electrochemical performance. In this work, the (Co,Mn)3O4 spinel was synthesized and anchored on reduced graphene oxide (rGO) nanosheets using a facile and single hydrothermal step with H2O2 as additive, no further additional calcination required. Analysis showed that this method gives a mixed spinel, i.e. (Co,Mn)3O4, having 2+ and 3+ Co and Mn ions in both the octahedral and tetrahedral sites of the spinel structure, with a nanocubic morphology roughly 20 nm in size. The nanocubes are bound onto the rGO nanosheet uniformly in a single hydrothermal process, then the as-prepared (Co,Mn)3O4/rGO composite was characterized as the anode materials for Li-ion battery (LIB). It can deliver 1130.6 mAh g-1 at current density of 100 mA g-1 with 98% of coulombic efficiency after 140 cycles. At 1000 mA g-1, the capacity can still maintain 750 mAh g-1, demonstrating excellent rate capabilities. Therefore, the one-step process is a facile and promising method to fabricate metal oxide/rGO composite materials for energy storage applications. PMID:27788161

  5. Two-step photolithography to fabricate multilevel microchannels.

    PubMed

    Choi, Sungyoung; Park, Je-Kyun

    2010-01-01

    In this paper, we study the variation of the thickness of patterned microchannel features in photoresist (PR) by two-step photolithography. The final PR thickness is determined by the thickness and width of the predefined PR pattern in the first-step lithography and the thickness of the spin-coated PR film in the second-step lithography. Thickness variation is demonstrated to be an important consideration within the critical pattern width that the capillary pressure is still dominant for forming the PR film thickness. With this mechanism of two-step photolithography, we demonstrate its ability to form multilevel channel features and its use to fabricate a cross-flow filter with two different pore sizes as a microfluidic application.

  6. Fabricating specialised orthopaedic implants using additive manufacturing

    NASA Astrophysics Data System (ADS)

    Unwin, Paul

    2014-03-01

    It has been hypothesised that AM is ideal for patient specific orthopaedic implants such as those used in bone cancer treatment, that can rapidly build structures such as lattices for bone and tissues to in-grow, that would be impossible using current conventional subtractive manufacturing techniques. The aim of this study was to describe the adoption of AM (direct metal laser sintering and electron beam melting) into the design manufacturing and post-manufacturing processes and the early clinical use. Prior to the clinical use of AM implants, extensive metallurgical and mechanical testing of both laser and electron beam fabrications were undertaken. Concurrently, post-manufacturing processes evaluated included hipping, cleaning and coating treatments. The first clinical application of a titanium alloy mega-implant was undertaken in November 2010. A 3D model of the pelvic wing implant was designed from CT scans. Novel key features included extensive lattice structures at the bone interfaces and integral flanges to fix the implant to the bone. The pelvic device was implanted with the aid of navigation and to date the patient remains active. A further 18 patient specific mega-implants have now been implanted. The early use of this advanced manufacturing route for patient specific implants has been very encouraging enabling the engineer to produce more advanced and anatomical conforming implants. However, there are a new set of design, manufacturing and regulatory challenges that require addressing to permit this technique to be used more widely. This technology is changing the design and manufacturing paradigm for the fabrication of specialised orthopaedic implants.

  7. One-step electrodeposition process to fabricate cathodic superhydrophobic surface

    NASA Astrophysics Data System (ADS)

    Chen, Zhi; Li, Feng; Hao, Limei; Chen, Anqi; Kong, Youchao

    2011-12-01

    In this work, a rapid one-step process is developed to fabricate superhydrophobic cathodic surface by electrodepositing copper plate in an electrolyte solution containing manganese chloride (MnCl2·4H2O), myristic acid (CH3(CH2)12COOH) and ethanol. The superhydrophobic surfaces were characterized by means of scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The shortest electrolysis time for fabricating a superhydrophobic surface is about 1 min, the measured maximum contact angle is 163° and rolling angle is less than 3°. Furthermore, this method can be easily extended to other conductive materials. The approach is time-saving and cheap, and it is supposed to have a promising future in industrial fields.

  8. Nucleophilic addition of reactive dyes on amidoximated acrylic fabrics.

    PubMed

    El-Shishtawy, Reda M; El-Zawahry, Manal M; Abdelghaffar, Fatma; Ahmed, Nahed S E

    2014-01-01

    Seven reactive dyes judiciously selected based on chemical structures and fixation mechanisms were applied at 2% of of shade on amidoximated acrylic fabrics. Amidoximated acrylic fabric has been obtained by a viable amidoximation process. The dyeability of these fabrics was evaluated with respect to the dye exhaustion, fixation, and colour strength under different conditions of temperature and dyeing time. Nucleophilic addition type reactive dyes show higher colour data compared to nucleophilic substitution ones. FTIR studies further implicate the binding of reactive dyes on these fabrics. A tentative mechanism is proposed to rationalize the high fixation yield obtained using nucleophilic addition type reactive dyes. Also, the levelling and fastness properties were evaluated for all dyes used. Excellent to good fastness and levelling properties were obtained for all samples irrespective of the dye used. The result of investigation offers a new method for a viable reactive dyeing of amidoximated acrylic fabrics.

  9. A Four-step Approach for Evaluation of Dose Additivity

    EPA Science Inventory

    A four step approach was developed for evaluating toxicity data on a chemical mixture for consistency with dose addition. Following the concepts in the U.S. EPA mixture guidance (EPA 2000), toxicologic interaction for a defined mixture (all components known) is departure from a c...

  10. Ion Milling On Steps for Fabrication of Nanowires

    NASA Technical Reports Server (NTRS)

    Yun, Minhee; Vasquez, Richard; Lee, Choonsup

    2006-01-01

    Arrays of nanowires having controlled dimensions can now be fabricated on substrates, optionally as integral parts of multilayer structures, by means of a cost-effective, high-yield process based on ion milling on steps. Nanowires made, variously, of semiconductors or metals are needed as components of sensors and high-density electronic circuits. Unlike prior processes used to fabricate nanowires, the present process does not involve electron-beam lithography, manipulation of nanoscopic objects by use of an atomic-force microscope, or any other technique that is inherently unsuitable for scaling up to mass production. In comparison with the prior processes, this process is rapid and simple. Wires having widths as small as a few tens of nanometers and lengths as long as millimeters have been fabricated by use of this process. The figure depicts a workpiece at different stages of the process. A silicon dioxide substrate is coated with a photoresist or poly(methyl methacrylate) [PMMA] to a thickness of as much as 500 nm. The photoresist or PMMA is patterned to form edges where wires are to be formed. A metal - either Pt or Ti - is deposited, by sputtering, to a thickness of as much as 200 nm. By ion milling at normal incidence, the thickness of the metal deposit is reduced until the only metal that remains is in the form of wall-like nanowires along the edges of the photoresist or PMMA. Finally, an oxygen plasma is used to remove the photoresist or PMMA, leaving only the nanowires on the substrate.

  11. Enhanced performance of wearable piezoelectric nanogenerator fabricated by two-step hydrothermal process

    SciTech Connect

    Qiu, Yu; Lei, Jixue; Yin, Bing; Zhang, Heqiu; Ji, Jiuyu; Hu, Lizhong; Bian, Jiming; Liu, Yanhong; Zhao, Yu; Luo, Yingmin

    2014-03-17

    A simple two-step hydrothermal process was proposed for enhancing the performance of the nanogenerator on flexible and wearable terylene-fabric substrate. With this method, a significant enhancement in output voltage of the nanogenerator from ∼10 mV to 7 V was achieved, comparing with the one by conventional one-step process. In addition, another advantage with the devices synthesized by two-step hydrothermal process was that their output voltages are only sensitive to strain rather than strain rate. The devices with a high output voltage have the ability to power common electric devices and will have important applications in flexible electronics and wearable devices.

  12. Design and fabrication of step mirrors used in space-modulated Fourier transform infrared spectrometer.

    PubMed

    Zheng, Ying; Liang, Jingqiu; Liang, Zhongzhu

    2013-01-14

    A model of miniaturized space-modulated Fourier transform infrared spectrometer (FTIR) is given. The two step mirrors as the key components are designed and a lithography-electroplating technique used to fabricate the small step mirror is proposed. We analyze the effect of the experiment results resulted from fabricating technics on the recovery spectrum in theory, and demonstrate that the lithography-electroplating technique is an effective method to fabricate the step mirror, which make miniaturized FTIR realized. We believe that the performances of FTIR can be better realized by optimizing experimental conditions to make this fabricating method more attractive.

  13. Fabrication of a Flexible Amperometric Glucose Sensor Using Additive Processes

    PubMed Central

    Du, Xiaosong; Durgan, Christopher J.; Matthews, David J.; Motley, Joshua R.; Tan, Xuebin; Pholsena, Kovit; Árnadóttir, Líney; Castle, Jessica R.; Jacobs, Peter G.; Cargill, Robert S.; Ward, W. Kenneth; Conley, John F.; Herman, Gregory S.

    2015-01-01

    This study details the use of printing and other additive processes to fabricate a novel amperometric glucose sensor. The sensor was fabricated using a Au coated 12.7 μm thick polyimide substrate as a starting material, where micro-contact printing, electrochemical plating, chloridization, electrohydrodynamic jet (e-jet) printing, and spin coating were used to pattern, deposit, chloridize, print, and coat functional materials, respectively. We have found that e-jet printing was effective for the deposition and patterning of glucose oxidase inks with lateral feature sizes between ~5 to 1000 μm in width, and that the glucose oxidase was still active after printing. The thickness of the permselective layer was optimized to obtain a linear response for glucose concentrations up to 32 mM and no response to acetaminophen, a common interfering compound, was observed. The use of such thin polyimide substrates allow wrapping of the sensors around catheters with high radius of curvature ~250 μm, where additive and microfabrication methods may allow significant cost reductions. PMID:26634186

  14. Effective Mechanical Properties of Lattice Material Fabricated by Material Extrusion Additive Manufacturing

    SciTech Connect

    Park, Sang-In; Choi, Seung-kyum; Rosen, David W; Duty, Chad E

    2014-01-01

    In this paper, a two-step homogenization method is proposed and implemented for evaluating effective mechanical properties of lattice structured material fabricated by the material extrusion additive manufacturing process. In order to consider the characteristics of the additive manufacturing process in estimation procedures, the levels of scale for homogenization are divided into three stages the levels of layer deposition, structural element, and lattice structure. The method consists of two transformations among stages. In the first step, the transformation between layer deposition and structural element levels is proposed to find the geometrical and material effective properties of structural elements in the lattice structure. In the second step, the method to estimate effective mechanical properties of lattice material is presented, which uses a unit cell and is based on the discretized homogenization method for periodic structure. The method is implemented for cubic lattice structure and compared to experimental results for validation purposes.

  15. Non toxic additives for improved fabric filter performance

    SciTech Connect

    Bustard, C.J.; Baldrey, K.E.; Ebner, T.G.

    1995-11-01

    The overall objective of this three-phase Small Business innovative Research (SBIR) program funded by the Department of Energy pittsburgh Energy Technology Center (PETC) is to commercialize a technology based upon the use of non-toxic, novel flue gas conditioning agents to improve particulate air toxic control and overall fabric filter performance. The ultimate objective of the Phase II program currently in progress is to demonstrate that the candidate additives are successful at full-scale on flue gas from a coal-fired utility boiler. This paper covers bench-scale field tests conducted during the period February through May, 1995. The bench-scale additives testing was conducted on a flue gas slipstream taken upstream of the existing particulate control device at a utility power plant firing a Texas lignite coal. These tests were preceded by extensive testing with additives in the laboratory using a simulated flue gas stream and re-dispersed flyash from the same power plant. The bench-scale field testing was undertaken to demonstrate the performance with actual flue gas of the bet candidate additives previously identified in the laboratory. Results from the bench-scale tests will be used to establish operating parameters for a larger-scale demonstration on either a single baghouse compartment or a full baghouse at the same site.

  16. Applications for Gradient Metal Alloys Fabricated Using Additive Manufacturing

    NASA Technical Reports Server (NTRS)

    Hofmann, Douglas C.; Borgonia, John Paul C.; Dillon, Robert P.; Suh, Eric J.; Mulder, jerry L.; Gardner, Paul B.

    2013-01-01

    Recently, additive manufacturing (AM) techniques have been developed that may shift the paradigm of traditional metal production by allowing complex net-shaped hardware to be built up layer-by-layer, rather than being machined from a billet. The AM process is ubiquitous with polymers due to their low melting temperatures, fast curing, and controllable viscosity, and 3D printers are widely available as commercial or consumer products. 3D printing with metals is inherently more complicated than with polymers due to their higher melting temperatures and reactivity with air, particularly when heated or molten. The process generally requires a high-power laser or other focused heat source, like an electron beam, for precise melting and deposition. Several promising metal AM techniques have been developed, including laser deposition (also called laser engineered net shaping or LENS® and laser deposition technology (LDT)), direct metal laser sintering (DMLS), and electron beam free-form (EBF). These machines typically use powders or wire feedstock that are melted and deposited using a laser or electron beam. Complex net-shape parts have been widely demonstrated using these (and other) AM techniques and the process appears to be a promising alternative to machining in some cases. Rather than simply competing with traditional machining for cost and time savings, the true advantage of AM involves the fabrication of hardware that cannot be produced using other techniques. This could include parts with "blind" features (like foams or trusses), parts that are difficult to machine conventionally, or parts made from materials that do not exist in bulk forms. In this work, the inventors identify that several AM techniques can be used to develop metal parts that change composition from one location in the part to another, allowing for complete control over the mechanical or physical properties. This changes the paradigm for conventional metal fabrication, which relies on an

  17. Multi-Step Deep Reactive Ion Etching Fabrication Process for Silicon-Based Terahertz Components

    NASA Technical Reports Server (NTRS)

    Jung-Kubiak, Cecile (Inventor); Reck, Theodore (Inventor); Chattopadhyay, Goutam (Inventor); Perez, Jose Vicente Siles (Inventor); Lin, Robert H. (Inventor); Mehdi, Imran (Inventor); Lee, Choonsup (Inventor); Cooper, Ken B. (Inventor); Peralta, Alejandro (Inventor)

    2016-01-01

    A multi-step silicon etching process has been developed to fabricate silicon-based terahertz (THz) waveguide components. This technique provides precise dimensional control across multiple etch depths with batch processing capabilities. Nonlinear and passive components such as mixers and multipliers waveguides, hybrids, OMTs and twists have been fabricated and integrated into a small silicon package. This fabrication technique enables a wafer-stacking architecture to provide ultra-compact multi-pixel receiver front-ends in the THz range.

  18. Fabrication of Turbine Disk Materials by Additive Manufacturing

    NASA Technical Reports Server (NTRS)

    Sudbrack, Chantal; Bean, Quincy A.; Cooper, Ken; Carter, Robert; Semiatin, S. Lee; Gabb, Tim

    2014-01-01

    Precipitation-strengthened, nickel-based superalloys are widely used in the aerospace and energy industries due to their excellent environmental resistance and outstanding mechanical properties under extreme conditions. Powder-bed additive manufacturing (AM) technologies offer the potential to revolutionize the processing of superalloy turbine components by eliminating the need for extensive inventory or expensive legacy tooling. Like selective laser melting (SLM), electron beam melting (EBM) constructs three-dimensional dense components layer-by-layer by melting and solidification of atomized, pre-alloyed powder feedstock within 50-200 micron layers. While SLM has been more widely used for AM of nickel alloys like 718, EBM offers several distinct advantages, such as less retained residual stress, lower risk of contamination, and faster build rates with multiple-electron-beam configurations. These advantages are particularly attractive for turbine disks, for which excessive residual stress and contamination can shorten disk life during high-temperature operation. In this presentation, we will discuss the feasibility of fabricating disk superalloy components using EBM AM. Originally developed using powder metallurgy forging processing, disk superalloys contain a higher refractory content and precipitate volume fraction than alloy 718, thus making them more prone to thermal cracking during AM. This and other challenges to produce homogeneous builds with desired properties will be presented. In particular, the quality of lab-scale samples fabricated via a design of experiments, in which the beam current, build temperature, and beam velocity were varied, will be summarized. The relationship between processing parameters, microstructure, grain orientation, and mechanical response will be discussed.

  19. One-step fabrication of robust fabrics with both-faced superhydrophobicity for the separation and capture of oil from water.

    PubMed

    Li, Jian; Yan, Long; Zhao, Yuzhu; Zha, Fei; Wang, Qingtao; Lei, Ziqiang

    2015-03-01

    In this work, a facile and inexpensive one-step sonochemistry irradiation method was developed for the fabrication of SiO2 nanoparticles functionalized with octadecyltrimethoxysilane and their in situ incorporation into cotton fabrics. The double sides of as-prepared fabrics show both superhydrophobic and superoleophilic properties simultaneously with a high water contact angle of 159 ± 1° and an oil contact angle of 0°. Thus, it can be used to separate and capture a series of oils from water, like kerosene, toluene and chloroform, etc. In addition, the as-prepared fabrics still have superhydrophobicity with a water contact angle of above 150° after 40 separation cycles with the separation efficiency for the kerosene-water mixture always above 94.6%. More importantly, the as-prepared fabrics showed robust and stable superhydrophobic properties towards hot water, many corrosive solutions (acidic, basic, salt liquids) and mechanical abrasion. Therefore, this reported fabric has the advantages of scalable fabrication, high separation efficiency, stable recyclability, and excellent durability, exhibiting the strong potential for industrial production.

  20. Direct laser additive fabrication system with image feedback control

    DOEpatents

    Griffith, Michelle L.; Hofmeister, William H.; Knorovsky, Gerald A.; MacCallum, Danny O.; Schlienger, M. Eric; Smugeresky, John E.

    2002-01-01

    A closed-loop, feedback-controlled direct laser fabrication system is disclosed. The feedback refers to the actual growth conditions obtained by real-time analysis of thermal radiation images. The resulting system can fabricate components with severalfold improvement in dimensional tolerances and surface finish.

  1. Fabrication High Resolution Metrology Target By Step And Repeat Method

    NASA Astrophysics Data System (ADS)

    Dusa, Mircea

    1983-10-01

    Based on the photolithography process generally used to generate high resolution masks for semiconductor I.C.S, we found a very useful industrial application of laser technology.First, we have generated high resolution metrology targets which are used in industrial measurement laser interferometers as difra.ction gratings. Secondi we have generated these targets using step and repeat machine, with He-Ne laser interferometer controlled state, as a pattern generator, due to suitable computer programming.Actually, high resolution metrology target, means two chromium plates, one of which is called the" rule" the other one the "vernier". In Fig.1 we have the configuration of the rule and the vernier. The rule has a succesion of 3 μM lines generated as a difraction grating on a 4 x 4 inch chromium blank. The vernier has several exposed fields( areas) having 3 - 15 μm lines, fields placed on very precise position on the chromium blank surface. High degree of uniformity, tight CD tolerances, low defect density required by the targets, creates specialised problems during processing. Details of the processing, together with experimental results will be presented. Before we start to enter into process details, we have to point out that the dimensional requirements of the reticle target, are quite similar or perhaps more strict than LSI master casks. These requirements presented in Fig.2.

  2. Facile fabrication of superhydrophobic surfaces on wood substrates via a one-step hydrothermal process

    NASA Astrophysics Data System (ADS)

    Liu, Ming; Qing, Yan; Wu, Yiqiang; Liang, Jin; Luo, Sha

    2015-03-01

    Superhydrophobic nanocomposite surfaces were successfully fabricated on wood substrates via a one-step hydrothermal process. The morphology of the nanocomposite surfaces was characterized using scanning electron microscopy (SEM), and the elemental composition was determined via energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) analysis, and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the crystallization of the anatase phase of TiO2 was prevented because of the presence of vinyltriethoxysilane [VTES, CH2CHSi(OC2H5)3] during the hydrothermal process. In addition, the nanocomposite contained Ti/Si particles with diameters ranging from 50 to 100 nm that thoroughly covered the wood substrate. Furthermore, the roughness coupled with the presence of low surface free energy groups led to superhydrophobicity; the static water contact angle (WCA) was as high as 153°, and the sliding angle was very low.

  3. Robust, Self-Healing Superhydrophobic Fabrics Prepared by One-Step Coating of PDMS and Octadecylamine

    NASA Astrophysics Data System (ADS)

    Xue, Chao-Hua; Bai, Xue; Jia, Shun-Tian

    2016-06-01

    A robust, self-healing superhydrophobic poly(ethylene terephthalate) (PET) fabric was fabricated by a convenient solution-dipping method using an easily available material system consisting of polydimethylsiloxane and octadecylamine (ODA). The surface roughness was formed by self-roughening of ODA coating on PET fibers without any lithography steps or adding any nanomaterials. The fabric coating was durable to withstand 120 cycles of laundry and 5000 cycles of abrasion without apparently changing the superhydrophobicity. More interestingly, the fabric can restore its super liquid-repellent property by 72 h at room temperature even after 20000 cycles of abrasion. Meanwhile, after being damaged chemically, the fabric can restore its superhydrophobicity automatically in 12 h at room temperature or by a short-time heating treatment. We envision that this simple but effective coating system may lead to the development of robust protective clothing for various applications.

  4. Robust, Self-Healing Superhydrophobic Fabrics Prepared by One-Step Coating of PDMS and Octadecylamine

    PubMed Central

    Xue, Chao-Hua; Bai, Xue; Jia, Shun-Tian

    2016-01-01

    A robust, self-healing superhydrophobic poly(ethylene terephthalate) (PET) fabric was fabricated by a convenient solution-dipping method using an easily available material system consisting of polydimethylsiloxane and octadecylamine (ODA). The surface roughness was formed by self-roughening of ODA coating on PET fibers without any lithography steps or adding any nanomaterials. The fabric coating was durable to withstand 120 cycles of laundry and 5000 cycles of abrasion without apparently changing the superhydrophobicity. More interestingly, the fabric can restore its super liquid-repellent property by 72 h at room temperature even after 20000 cycles of abrasion. Meanwhile, after being damaged chemically, the fabric can restore its superhydrophobicity automatically in 12 h at room temperature or by a short-time heating treatment. We envision that this simple but effective coating system may lead to the development of robust protective clothing for various applications. PMID:27264995

  5. Robust, Self-Healing Superhydrophobic Fabrics Prepared by One-Step Coating of PDMS and Octadecylamine.

    PubMed

    Xue, Chao-Hua; Bai, Xue; Jia, Shun-Tian

    2016-01-01

    A robust, self-healing superhydrophobic poly(ethylene terephthalate) (PET) fabric was fabricated by a convenient solution-dipping method using an easily available material system consisting of polydimethylsiloxane and octadecylamine (ODA). The surface roughness was formed by self-roughening of ODA coating on PET fibers without any lithography steps or adding any nanomaterials. The fabric coating was durable to withstand 120 cycles of laundry and 5000 cycles of abrasion without apparently changing the superhydrophobicity. More interestingly, the fabric can restore its super liquid-repellent property by 72 h at room temperature even after 20000 cycles of abrasion. Meanwhile, after being damaged chemically, the fabric can restore its superhydrophobicity automatically in 12 h at room temperature or by a short-time heating treatment. We envision that this simple but effective coating system may lead to the development of robust protective clothing for various applications.

  6. Robust, Self-Healing Superhydrophobic Fabrics Prepared by One-Step Coating of PDMS and Octadecylamine.

    PubMed

    Xue, Chao-Hua; Bai, Xue; Jia, Shun-Tian

    2016-01-01

    A robust, self-healing superhydrophobic poly(ethylene terephthalate) (PET) fabric was fabricated by a convenient solution-dipping method using an easily available material system consisting of polydimethylsiloxane and octadecylamine (ODA). The surface roughness was formed by self-roughening of ODA coating on PET fibers without any lithography steps or adding any nanomaterials. The fabric coating was durable to withstand 120 cycles of laundry and 5000 cycles of abrasion without apparently changing the superhydrophobicity. More interestingly, the fabric can restore its super liquid-repellent property by 72 h at room temperature even after 20000 cycles of abrasion. Meanwhile, after being damaged chemically, the fabric can restore its superhydrophobicity automatically in 12 h at room temperature or by a short-time heating treatment. We envision that this simple but effective coating system may lead to the development of robust protective clothing for various applications. PMID:27264995

  7. Facile fabrication of HDPE-g-MA/nanodiamond nanocomposites via one-step reactive blending

    PubMed Central

    2012-01-01

    In this letter, nanocomposites based on maleic anhydride grafted high density polyethylene (HDPE-g-MA) and amine-functionalized nanodiamond (ND) were fabricated via one-step reactive melt-blending, generating a homogeneous dispersion of ND, as evidenced by transmission electron microscope observations. Thermal analysis results suggest that addition of ND does not affect significantly thermal stability of polymer matrix in nitrogen. However, it was interestingly found that incorporating pure ND decreases the thermal oxidation degradation stability temperature, but blending amino-functionalized ND via reactive processing significantly enhances it of HDPE in air condition. Most importantly, cone tests revealed that both ND additives and reactive blending greatly reduce the heat release rate of HDPE. The results suggest that ND has a potential application as flame retardant alternative for polymers. Tensile results show that adding ND considerably enhances Young’s modulus, and reactive blending leads to further improvement in Young’s modulus while hardly reducing the elongation at break of HDPE. PMID:22747773

  8. Fabrication of Flex Joint Utilizing Additively Manufactured Parts

    NASA Technical Reports Server (NTRS)

    Eddleman, David; Richard, Jim

    2015-01-01

    The Selective Laser Melting (SLM) manufacturing technique has been utilized in the manufacture of a flex joint typical of those found in rocket engine and main propulsion system ducting. The SLM process allowed for the combination of parts that are typically machined separately and welded together. This resulted in roughly a 65% reduction of the total number of parts, roughly 70% reduction in the total number of welds, and an estimated 60% reduction in the number of machining operations. The majority of the new design was in three SLM pieces. These pieces, as well as a few traditionally fabricated parts, were assembled into a complete unit, which has been pressure tested. The design and planned cryogenic testing of the unit will be presented.

  9. Single-Step Fabrication of Computationally Designed Microneedles by Continuous Liquid Interface Production.

    PubMed

    Johnson, Ashley R; Caudill, Cassie L; Tumbleston, John R; Bloomquist, Cameron J; Moga, Katherine A; Ermoshkin, Alexander; Shirvanyants, David; Mecham, Sue J; Luft, J Christopher; DeSimone, Joseph M

    2016-01-01

    Microneedles, arrays of micron-sized needles that painlessly puncture the skin, enable transdermal delivery of medications that are difficult to deliver using more traditional routes. Many important design parameters, such as microneedle size, shape, spacing, and composition, are known to influence efficacy, but are notoriously difficult to alter due to the complex nature of microfabrication techniques. Herein, we utilize a novel additive manufacturing ("3D printing") technique called Continuous Liquid Interface Production (CLIP) to rapidly prototype sharp microneedles with tuneable geometries (size, shape, aspect ratio, spacing). This technology allows for mold-independent, one-step manufacturing of microneedle arrays of virtually any design in less than 10 minutes per patch. Square pyramidal CLIP microneedles composed of trimethylolpropane triacrylate, polyacrylic acid and photopolymerizable derivatives of polyethylene glycol and polycaprolactone were fabricated to demonstrate the range of materials that can be utilized within this platform for encapsulating and controlling the release of therapeutics. These CLIP microneedles effectively pierced murine skin ex vivo and released the fluorescent drug surrogate rhodamine.

  10. Single-Step Fabrication of Computationally Designed Microneedles by Continuous Liquid Interface Production.

    PubMed

    Johnson, Ashley R; Caudill, Cassie L; Tumbleston, John R; Bloomquist, Cameron J; Moga, Katherine A; Ermoshkin, Alexander; Shirvanyants, David; Mecham, Sue J; Luft, J Christopher; DeSimone, Joseph M

    2016-01-01

    Microneedles, arrays of micron-sized needles that painlessly puncture the skin, enable transdermal delivery of medications that are difficult to deliver using more traditional routes. Many important design parameters, such as microneedle size, shape, spacing, and composition, are known to influence efficacy, but are notoriously difficult to alter due to the complex nature of microfabrication techniques. Herein, we utilize a novel additive manufacturing ("3D printing") technique called Continuous Liquid Interface Production (CLIP) to rapidly prototype sharp microneedles with tuneable geometries (size, shape, aspect ratio, spacing). This technology allows for mold-independent, one-step manufacturing of microneedle arrays of virtually any design in less than 10 minutes per patch. Square pyramidal CLIP microneedles composed of trimethylolpropane triacrylate, polyacrylic acid and photopolymerizable derivatives of polyethylene glycol and polycaprolactone were fabricated to demonstrate the range of materials that can be utilized within this platform for encapsulating and controlling the release of therapeutics. These CLIP microneedles effectively pierced murine skin ex vivo and released the fluorescent drug surrogate rhodamine. PMID:27607247

  11. Single-Step Fabrication of Computationally Designed Microneedles by Continuous Liquid Interface Production

    PubMed Central

    Johnson, Ashley R.; Caudill, Cassie L.; Tumbleston, John R.; Bloomquist, Cameron J.; Moga, Katherine A.; Ermoshkin, Alexander; Shirvanyants, David; Mecham, Sue J.; Luft, J. Christopher; DeSimone, Joseph M.

    2016-01-01

    Microneedles, arrays of micron-sized needles that painlessly puncture the skin, enable transdermal delivery of medications that are difficult to deliver using more traditional routes. Many important design parameters, such as microneedle size, shape, spacing, and composition, are known to influence efficacy, but are notoriously difficult to alter due to the complex nature of microfabrication techniques. Herein, we utilize a novel additive manufacturing (“3D printing”) technique called Continuous Liquid Interface Production (CLIP) to rapidly prototype sharp microneedles with tuneable geometries (size, shape, aspect ratio, spacing). This technology allows for mold-independent, one-step manufacturing of microneedle arrays of virtually any design in less than 10 minutes per patch. Square pyramidal CLIP microneedles composed of trimethylolpropane triacrylate, polyacrylic acid and photopolymerizable derivatives of polyethylene glycol and polycaprolactone were fabricated to demonstrate the range of materials that can be utilized within this platform for encapsulating and controlling the release of therapeutics. These CLIP microneedles effectively pierced murine skin ex vivo and released the fluorescent drug surrogate rhodamine. PMID:27607247

  12. Clinical and Laboratory Steps for Fabricating a Complete-Arch Fixed Prosthesis Using CAD/CAM.

    PubMed

    Keerthi, Senthil; Proussaefs, Periklis; Lozada, Jaime

    2015-01-01

    The fabrication of a full-arch maxillary prosthesis has been associated with several prosthetic complications and difficulties. Even though it has been reported that phonetics, esthetics, and proper lip support are difficult to achieve, there is a scarcity in the literature regarding the clinical and laboratory procedures necessary to minimize these complications. This article provides clinical and laboratory steps that may enable the clinician to achieve more predictable restorative results when using computer-aided design/computer-assisted manufacture (CAD/CAM) to fabricate a full-arch maxillary implant-supported prosthesis. The technique presented here describes the use of an implant-retained diagnostic wax-up that is subsequently duplicated to an interim polymethylmethacrylate prosthesis using CAD/CAM before fabricating the definitive restoration.

  13. Single-step laser-based fabrication and patterning of cell-encapsulated alginate microbeads

    PubMed Central

    Kingsley, DM; Dias, AD; Chrisey, DB; Corr, DT

    2014-01-01

    Alginate can be used to encapsulate mammalian cells and for the slow release of small molecules. Packaging alginate as microbead structures allows customizable delivery for tissue engineering, drug release, or contrast agents for imaging. However, state-of-the-art microbead fabrication has limited range in achievable bead sizes, and poor control over bead placement, which may be desired to localize cellular signaling or delivery. Herein, we present a novel, laser-based method for single-step fabrication and precise planar placement of alginate microbeads. Our results show that bead size is controllable within 8%, and fabricated microbeads can remain immobilized within 2% of their target placement. Demonstration of this technique using human breast cancer cells shows that cells encapsulated within these microbeads survive at a rate of 89.6%, decreasing to 84.3% after five days in culture. Infusing rhodamine dye into microbeads prior to fluorescent microscopy shows their 3D spheroidal geometry and the ability to sequester small molecules. Microbead fabrication and patterning is compatible with conventional cellular transfer and patterning by laser direct-write, allowing location-based cellular studies. While this method can also be used to fabricate microbeads en masse for collection, the greatest value to tissue engineering and drug delivery studies and applications lies in the pattern registry of printed microbeads. PMID:24192221

  14. Surface Modified Particles By Multi-Step Addition And Process For The Preparation Thereof

    DOEpatents

    Cook, Ronald Lee; Elliott, Brian John; Luebben, Silvia DeVito; Myers, Andrew William; Smith, Bryan Matthew

    2006-01-17

    The present invention relates to a new class of surface modified particles and to a multi-step surface modification process for the preparation of the same. The multi-step surface functionalization process involves two or more reactions to produce particles that are compatible with various host systems and/or to provide the particles with particular chemical reactivities. The initial step comprises the attachment of a small organic compound to the surface of the inorganic particle. The subsequent steps attach additional compounds to the previously attached organic compounds through organic linking groups.

  15. One-step fabrication of nanowire-grid polarizers using liquid-bridge-mediated nanotransfer molding

    PubMed Central

    2012-01-01

    Ag nanowire-grid polarizers (NWGPs) were prepared by a one-step fabrication method, called liquid-bridge-mediated nanotransfer molding (LB-nTM). LB-nTM is a new direct nano-patterning method based on the direct transfer of various materials from a mold to a substrate via liquid layer. We fabricated NWGPs with Ag nanowire arrays (81 nm parallel lines and 119 nm spaces) on 2.5 in. transparent substrates by LB-nTM using an Ag nanoparticle solution. The maximum and minimum transmittances of the Ag NWGP at 800 nm were 80% and 10%, respectively. PMID:22738252

  16. Additive fabrication of microstructures using self-assembled organic thin-film templates

    NASA Astrophysics Data System (ADS)

    Jeon, Noo Li

    A novel approach to thin film patterning is described in this thesis: printed self-assembled monolayers (SAMs) were used as a template for the selective deposition of metal and ceramic thin films. In contrast to the conventional subtractive patterning processes involving photolithography and reactive ion etching, thin films were patterned in an additive manner with two or three maskless (photolithography-free) steps. First, SAMs of octadecyltrichlorosilane (OTS) were patterned by microcontact printing (muCP) with sub-micron to centimeter resolution on a variety of substrates such as SiOsb2/Si, TiN, indium tin oxide, plasma modified polyimide, and sapphire. The patterned SAMs allow manipulation of such surface properties as adsorption, wetting, and adhesion which are used for the selective deposition of thin films via a chemical route. The microcontact printed OTS SAMs were characterized with reflection absorption infrared spectroscopy (RAIRS), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). It was found that after 30s of microcontact printing (using 10 mM OTS solution in hexane), well oriented and fully covered SAMs are formed. These monolayers are chemically and thermally robust enough to withstand the CVD and sol-gel processing conditions. Effects of such processing variables as concentration of OTS, substrate, moisture, and duration of contact on the structure of the OTS films were also studied. Thin films of metals such as copper, palladium, and platinum (by chemical vapor deposition, CVD) and of ceramics such as LiNbOsb3, Pb(Zr,Ti)Osb3 (PZT), Tasb2Osb5 and (Pb,La)TiOsb3 (PLT) (from corresponding sol-gel precursors) were selectively deposited on surfaces modified with OTS SAMs by microcontact printing. This thesis discusses several examples of microstructures of copper, palladium, and platinum fabricated by selective CVD, including the fabrication of thin-film interconnects (with line widths of 0

  17. A simple two-step method to fabricate highly transparent ITO/polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Liu, Haitao; Zeng, Xiaofei; Kong, Xiangrong; Bian, Shuguang; Chen, Jianfeng

    2012-09-01

    Transparent functional indium tin oxide (ITO)/polymer nanocomposite films were fabricated via a simple approach with two steps. Firstly, the functional monodisperse ITO nanoparticles were synthesized via a facile nonaqueous solvothermal method using bifunctional chemical agent (N-methyl-pyrrolidone, NMP) as the reaction solvent and surface modifier. Secondly, the ITO/acrylics polyurethane (PUA) nanocomposite films were fabricated by a simple sol-solution mixing method without any further surface modification step as often employed traditionally. Flower-like ITO nanoclusters with about 45 nm in diameter were mono-dispersed in ethyl acetate and each nanocluster was assembled by nearly spherical nanoparticles with primary size of 7-9 nm in diameter. The ITO nanoclusters exhibited an excellent dispersibility in polymer matrix of PUA, remaining their original size without any further agglomeration. When the loading content of ITO nanoclusters reached to 5 wt%, the transparent functional nanocomposite film featured a high transparency more than 85% in the visible light region (at 550 nm), meanwhile cutting off near-infrared radiation about 50% at 1500 nm and blocking UV ray about 45% at 350 nm. It could be potential for transparent functional coating materials applications.

  18. One-step controllable fabrication of superhydrophobic surfaces with special composite structure on zinc substrates.

    PubMed

    Ning, Tao; Xu, Wenguo; Lu, Shixiang

    2011-09-01

    Stable superhydrophobic platinum surfaces have been effectively fabricated on the zinc substrates through one-step replacement deposition process without further modification or any other post-treatment procedures. The fabrication process was controllable, which could be testified by various morphologies and hydrophobic properties of different prepared samples. By conducting SEM and water CA analysis, the effects of reaction conditions on the surface morphology and hydrophobicity of the resulting surfaces were carefully studied. The results show that the optimum condition of superhydrophobic surface fabrication depends largely on the positioning of zinc plate and the concentrations of reactants. When the zinc plate was placed vertically and the concentration of PtCl(4) solution was 5 mmol/L, the zinc substrate would be covered by a novel and interesting composite structure. The structure was composed by microscale hexagonal cavities, densely packed nanoparticles layer and top micro- and nanoscale flower-like structures, which exhibit great surface roughness and porosity contributing to the superhydrophobicity. The maximal CA value of about 171° was obtained under the same reaction condition. The XRD, XPS and EDX results indicate that crystallite pure platinum nanoparticles were aggregated on the zinc substrates in accordance with a free deposition way.

  19. Closed hollow bulb obturator--one-step fabrication: a clinical report.

    PubMed

    Buzayan, Muaiyed M; Ariffin, Yusnidar T; Yunus, Norsiah

    2013-10-01

    A method is described for the fabrication of a closed hollow bulb obturator prosthesis using a hard thermoforming splint material and heat-cured acrylic resin. The technique allowed the thickness of the thermoformed bulb to be optimized for weight reduction, while the autopolymerized seal area was covered in heat-cured acrylic resin, thus eliminating potential leakage and discoloration. This technique permits the obturator prosthesis to be processed to completion from the wax trial denture without additional laboratory investing, flasking, and processing.

  20. A Four Step Approach to Evaluate Mixtures for Consistency with Dose Addition

    EPA Science Inventory

    We developed a four step approach for evaluating chemical mixture data for consistency with dose addition for use in environmental health risk assessment. Following the concepts in the U.S. EPA mixture risk guidance (EPA 2000a,b), toxicological interaction for a defined mixture (...

  1. One-step solution immersion process to fabricate superhydrophobic surfaces on light alloys.

    PubMed

    Ou, Junfei; Hu, Weihua; Xue, Mingshan; Wang, Fajun; Li, Wen

    2013-10-23

    A simple and universal one-step process bas been developed to render light alloys (including AZ91D Mg alloy, 5083 Al alloy, and TC4 Ti alloy) superhydrophobic by immersing the substrates in a solution containing low-surface-energy molecules of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS, 20 μL), ethanol (10 mL), and H2O (10 mL for Al and Mg alloy)/H2O2 (15%, 10 mL for Ti alloy). Field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and water contact angle measurements have been performed to characterize the morphological features, chemical composition, and wettability of the surfaces, respectively. The results indicate that the treated light alloys are rough-structured and covered by PFOTS molecules; consequently, the surfaces show static contact angles higher than 150° and sliding angles lower than 10°. This research reveals that it is feasible to fabricate superhydrophobic surfaces (SHS) easily and effectively without involving the traditional two-step processes. Moreover, this one-step process may find potential application in the field of industrial preparation of SHS because of its simplicity and universality.

  2. Reference Alloy Waste Form Fabrication and Initiation of Reducing Atmosphere and Reductive Additives Study on Alloy Waste Form Fabrication

    SciTech Connect

    S.M. Frank; T.P. O'Holleran; P.A. Hahn

    2011-09-01

    This report describes the fabrication of two reference alloy waste forms, RAW-1(Re) and RAW-(Tc) using an optimized loading and heating method. The composition of the alloy materials was based on a generalized formulation to process various proposed feed streams resulting from the processing of used fuel. Waste elements are introduced into molten steel during alloy fabrication and, upon solidification, become incorporated into durable iron-based intermetallic phases of the alloy waste form. The first alloy ingot contained surrogate (non-radioactive), transition-metal fission products with rhenium acting as a surrogate for technetium. The second alloy ingot contained the same components as the first ingot, but included radioactive Tc-99 instead of rhenium. Understanding technetium behavior in the waste form is of particular importance due the longevity of Tc-99 and its mobility in the biosphere in the oxide form. RAW-1(Re) and RAW-1(Tc) are currently being used as test specimens in the comprehensive testing program investigating the corrosion and radionuclide release mechanisms of the representative alloy waste form. Also described in this report is the experimental plan to study the effects of reducing atmospheres and reducing additives to the alloy material during fabrication in an attempt to maximize the oxide content of waste streams that can be accommodated in the alloy waste form. Activities described in the experimental plan will be performed in FY12. The first aspect of the experimental plan is to study oxide formation on the alloy by introducing O2 impurities in the melt cover gas or from added oxide impurities in the feed materials. Reducing atmospheres will then be introduced to the melt cover gas in an attempt to minimize oxide formation during alloy fabrication. The second phase of the experimental plan is to investigate melting parameters associated with alloy fabrication to allow the separation of slag and alloy components of the melt.

  3. Plastic-Syringe Induced Silicone Contamination in Organic Photvoltaic Fabrication: Implications for Small-Volume Additives

    SciTech Connect

    Carr, John A.; Nalwa, Kanwar S.; Mahadevapuram, Rakesh; Chen, Yuqing; Anderegg, James; Chaudhary, Sumit

    2012-05-15

    Herein, the implications of silicone contamination found in solution-processed conjugated polymer solar cells are explored. Similar to a previous work based on molecular cells, we find this contamination as a result of the use of plastic syringes during fabrication. However, in contrast to the molecular case, we find that glass-syringe fabricated devices give superior performance than plastic-syringe fabricated devices in poly(3-hexylthiophene)-based cells. We find that the unintentional silicone addition alters the solution’s wettability, which translates to a thinner, less absorbent film on spinning. With many groups studying the effects of small-volume additives, this work should be closely considered as many of these additives may also directly alter the solutions’ wettability, or the amount of silicone dissolved off the plastic syringes, or both. Thereby, film thickness, which generally is not reported in detail, can vary significantly from device to device.

  4. Blazed vector grating liquid crystal cells with photocrosslinkable polymeric alignment films fabricated by one-step polarizer rotation method

    NASA Astrophysics Data System (ADS)

    Kawai, Kotaro; Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2014-12-01

    Blazed vector grating liquid crystal (LC) cells, in which the directors of low-molar-mass LCs are antisymmetrically distributed, were fabricated by one-step exposure of an empty glass cell inner-coated with a photocrosslinkable polymer LC (PCLC) to UV light. By adopting a LC cell structure, twisted nematic (TN) and homogeneous (HOMO) alignments were obtained in the blazed vector grating LC cells. Moreover, the diffraction efficiency of the blazed vector grating LC cells was greatly improved by increasing the thickness of the device in comparison with that of a blazed vector grating with a thin film structure obtained in our previous study. In addition, the diffraction efficiency and polarization states of ±1st-order diffracted beams from the resultant blazed vector grating LC cells were controlled by designing a blazed pattern in the alignment films, and these diffraction properties were well explained on the basis of Jones calculus and the elastic continuum theory of nematic LCs.

  5. Two-step fabrication technique of gold tips for use in point-contact spectroscopy

    SciTech Connect

    Narasiwodeyar, S.; Dwyer, M.; Liu, M.; Park, W. K. Greene, L. H.

    2015-03-15

    For a successful point-contact spectroscopy (PCS) measurement, metallic tips of proper shape and smoothness are essential to ensure the ballistic nature of a point-contact junction. Until recently, the fabrication of Au tips suitable for use in point-contact spectroscopy has remained more of an art involving a trial and error method rather than an automated scientific process. To address these issues, we have developed a technique with which one can prepare high quality Au tips reproducibly and systematically. It involves an electronic control of the driving voltages used for an electrochemical etching of a gold wire in a HCl-glycerol mixture or a HCl solution. We find that a stopping current, below which the circuit is set to shut off, is a single very important parameter to produce an Au tip of desired shape. We present detailed descriptions for a two-step etching process for Au tips and also test results from PCS measurements using them.

  6. One-step electrochemical fabrication of bilayered MgO/polymer coating on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Liang, Jun; Zhang, Ren-Hui; Peng, Zhen-Jun; Liu, Bai-Xing

    2014-09-01

    This research demonstrates a novel one-step electrochemical method to fabricate thick bilayer coatings on magnesium alloy in acid phosphate electrolyte containing aniline monomer and styrene-acrylic emulsion (SAE) with pulsed DC voltage. The morphologies, XRD and FTIR results show that the bilayer coating consists of an inner oxide layer and an outer polyaniline (PANI)/SAE composite layer. It is believed that the bilayered structure achieved results from a hybrid process combining electropolymerization (EPM) of aniline, electrophoretic deposition (EPD) of SAE and plasma electrolyte oxidation (PEO) of magnesium alloy substrate. Electrochemical corrosion tests indicate that the bilayer coating can provide superior corrosion protection to the magnesium alloy substrate in 3.5 wt.% NaCl solution.

  7. Double-layer anisotropic light diffusion films fabricated using a two-step UV curing technique

    NASA Astrophysics Data System (ADS)

    Kusama, Kentaro; Ishinabe, Takahiro; Katagiri, Baku; Orui, Tomoo; Shoshi, Satoru; Fujikake, Hideo

    2016-04-01

    We developed a novel light diffusion film with a double diffusion layer structure for high reflectivity and a wide diffusion angle range. We demonstrated that the internal layer structure of the light diffusion film is controlled by the diffusion angle of the ultraviolet (UV) light used for photopolymerization. We successfully fabricated two different diffusion layers in a single polymer film using a two-step UV curing process and achieved a wide diffusion angle range and high reflectivity normal to the film surface. Our light diffusion film can control the distribution of diffused light, and should contribute to the development of future low-power reflective displays with high reflectivity similar to the white paper.

  8. Single-step fabrication of microfluidic channels filled with nanofibrous membrane using femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Tavangar, Amirhossein; Tan, Bo; Venkatakrishnan, K.

    2010-08-01

    In this paper, we demonstrate a new method of fabricating silicon microfluidic channels filled with a porous nanofibrous structure utilizing a femtosecond laser. The nanofibrous structure can act as a membrane used for microfiltration. This method allows us to generate both the microfluidic channel and the fibrous nanostructure in a single step under ambient conditions. Due to laser irradiation, a large number of nanoparticles ablate from the channel surface, and then aggregate and grow into porous nanofibrous structures and fill the channels. Energy dispersive x-ray spectroscopy (EDS) analysis was conducted to examine the oxygen concentration in the membrane structure. Our results demonstrated that by controlling the laser parameters including pulse repetition, pulse width and scanning speed, different microfluidic channels with a variety of porosity could be obtained.

  9. Fabrication of metallic nanodisc hexagonal arrays using nanosphere lithography and two-step lift-off.

    PubMed

    Huang, Xiaolu; Ratchford, Daniel; Pehrsson, Pehr E; Yeom, Junghoon

    2016-09-30

    Nanosphere lithography (NSL) has been widely used as an inexpensive method to create periodic arrays of metallic nanoparticles or nanodiscs on substrates. However, most nanodisc arrays derived from a NSL template are restricted to hexagonally-ordered triangular arrays because the metal layer is deposited onto the interstices between the nanospheres. Metallic nanodisc arrays with the same arrangement as the original nanosphere array have been rarely reported. Here, we demonstrate a facile, low-cost method to fabricate large-area hexagonal arrays of metallic nanodiscs using an NSL template combined with a two-step lift-off process. We employ a bi-layer of two dissimilar metals to create a re-entrant sidewall profile to undercut the sacrificial layer and facilitate the final lift-off of the metallic nanodiscs. The quality of the nanodisc pattern and the array periodicity is determined using statistical image analysis and compared to the original nanosphere array in terms of size distribution, surface smoothness, and array pitch. This nanodisc array is used as an etch mask to create a vertically-aligned Si nanowire array. This combined approach is a scalable and inexpensive fabrication method for creating relatively large-area, ordered arrays of various nanostructures.

  10. Fabrication of metallic nanodisc hexagonal arrays using nanosphere lithography and two-step lift-off.

    PubMed

    Huang, Xiaolu; Ratchford, Daniel; Pehrsson, Pehr E; Yeom, Junghoon

    2016-09-30

    Nanosphere lithography (NSL) has been widely used as an inexpensive method to create periodic arrays of metallic nanoparticles or nanodiscs on substrates. However, most nanodisc arrays derived from a NSL template are restricted to hexagonally-ordered triangular arrays because the metal layer is deposited onto the interstices between the nanospheres. Metallic nanodisc arrays with the same arrangement as the original nanosphere array have been rarely reported. Here, we demonstrate a facile, low-cost method to fabricate large-area hexagonal arrays of metallic nanodiscs using an NSL template combined with a two-step lift-off process. We employ a bi-layer of two dissimilar metals to create a re-entrant sidewall profile to undercut the sacrificial layer and facilitate the final lift-off of the metallic nanodiscs. The quality of the nanodisc pattern and the array periodicity is determined using statistical image analysis and compared to the original nanosphere array in terms of size distribution, surface smoothness, and array pitch. This nanodisc array is used as an etch mask to create a vertically-aligned Si nanowire array. This combined approach is a scalable and inexpensive fabrication method for creating relatively large-area, ordered arrays of various nanostructures. PMID:27559986

  11. Fabrication of metallic nanodisc hexagonal arrays using nanosphere lithography and two-step lift-off

    NASA Astrophysics Data System (ADS)

    Huang, Xiaolu; Ratchford, Daniel; Pehrsson, Pehr E.; Yeom, Junghoon

    2016-09-01

    Nanosphere lithography (NSL) has been widely used as an inexpensive method to create periodic arrays of metallic nanoparticles or nanodiscs on substrates. However, most nanodisc arrays derived from a NSL template are restricted to hexagonally-ordered triangular arrays because the metal layer is deposited onto the interstices between the nanospheres. Metallic nanodisc arrays with the same arrangement as the original nanosphere array have been rarely reported. Here, we demonstrate a facile, low-cost method to fabricate large-area hexagonal arrays of metallic nanodiscs using an NSL template combined with a two-step lift-off process. We employ a bi-layer of two dissimilar metals to create a re-entrant sidewall profile to undercut the sacrificial layer and facilitate the final lift-off of the metallic nanodiscs. The quality of the nanodisc pattern and the array periodicity is determined using statistical image analysis and compared to the original nanosphere array in terms of size distribution, surface smoothness, and array pitch. This nanodisc array is used as an etch mask to create a vertically-aligned Si nanowire array. This combined approach is a scalable and inexpensive fabrication method for creating relatively large-area, ordered arrays of various nanostructures.

  12. The Use of Additive Manufacturing for Fabrication of Multi-Function Small Satellite Structures

    SciTech Connect

    Horais, Brian J; Love, Lonnie J; Dehoff, Ryan R

    2013-01-01

    The use of small satellites in constellations is limited only by the growing functionality of smallsats themselves. Additive manufacturing provides exciting new design opportunities for development of multifunction CubeSat structures that integrate such functions as propulsion and thermal control into the satellite structures themselves. Manufacturing of these complex multifunction structures is now possible in lightweight, high strength, materials such as titanium by using existing electron beam melting additive manufacturing processes. However, the use of today's additive manufacturing capabilities is often cost-prohibitive for small companies due to the large capital investments required. To alleviate this impediment the U.S. Department of Energy has established a Manufacturing Demonstration Facility (MDF) at their Oak Ridge National Laboratory (ORNL) in Tennessee that provides industry access to a broad range of energy-efficient additive manufacturing equipment for collaborative use by both small and large organizations. This paper presents a notional CubeSat multifunction design that integrates the propulsion system into a three-unit (3U) CubeSat structure. The full-scale structure has been designed and fabricated at the ORNL MDF. The use of additive manufacturing for spacecraft fabrication is opening up many new possibilities in design and fabrication capabilities for what had previously been impossible structures to fabricate.

  13. Closed hollow bulb obturator--one-step fabrication: a clinical report.

    PubMed

    Buzayan, Muaiyed M; Ariffin, Yusnidar T; Yunus, Norsiah

    2013-10-01

    A method is described for the fabrication of a closed hollow bulb obturator prosthesis using a hard thermoforming splint material and heat-cured acrylic resin. The technique allowed the thickness of the thermoformed bulb to be optimized for weight reduction, while the autopolymerized seal area was covered in heat-cured acrylic resin, thus eliminating potential leakage and discoloration. This technique permits the obturator prosthesis to be processed to completion from the wax trial denture without additional laboratory investing, flasking, and processing. PMID:23551843

  14. Single-step approach for fabrication of vancomycin-bonded silica monolith as chiral stationary phase.

    PubMed

    Hsieh, Ming-Lung; Chau, Lai-Kwan; Hon, Yung-Son

    2014-09-01

    A vancomycin-bonded silica monolithic column for capillary electrochromatography (CEC) was prepared by a single-step in situ sol-gel approach. This sol-gel process incorporates a synthetic sol-gel precursor which contains a macrocyclic antibiotic, vancomycin, to form a porous silica network inside a fused-silica capillary. To avoid degradation of vancomycin during the column fabrication, a mild step was adopted into the sol-gel process. The performance of the vancomycin chiral stationary phase was investigated by CEC in both the reversed-phase mode and the normal-phase mode. The vancomycin chiral stationary phase was optimized with respect to vancomycin loading in the reversed-phase mode for chiral separation of thalidomide enantiomers. The best efficiency and resolution values of 94600plates/m and 5.79, respectively, were achieved. The optimized column was further applied to chiral separation of alprenolol enantiomers. A plate height of less than 7μm for the first eluted enantiomer of alprenolol was obtained in an aqueous mobile phase at a flow rate of 0.74mm/s. Using enantiomers of seven β-blockers and some other basic enantiomers as test analytes, separation efficiencies of up to 148100plates/m in the reversed-phase mode and up to 138100plates/m in the normal-phase mode were achieved.

  15. One-step fabrication of near superhydrophobic aluminum surface by nanosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Jagdheesh, R.; García-Ballesteros, J. J.; Ocaña, J. L.

    2016-06-01

    Inspired by the micro and nano structures of biological surface such as lotus leaf, rice leaves, etc. a functional near superhydrophobic surface of pure aluminum has been fabricated using one-step nanosecond laser processing. Thin aluminum sheets are micro-patterned with ultraviolet laser pulses to create near superhydrophobic surface in one-step direct laser writing technique. The impact of number of pulses/microhole with respect to the geometry and static contact angle measurements has been investigated. The microstructure shows the formation of blind microholes along with the micro-wall by laser processing, which improves the composite interface between the three phases such as water, air and solid, thus enhance the wetting property of the surface. The geometrical changes are supported by the chemical changes induced on the surface for improving the degree of hydrophobicity. Laser processed microholes exhibited near superhydrophobic surface with SCA measurement of 148 ± 3°. The static contact angle values are very consistent for repeated measurement at same area and across the laser patterned surface.

  16. Fabrication of efficient planar perovskite solar cells using a one-step chemical vapor deposition method

    PubMed Central

    Tavakoli, Mohammad Mahdi; Gu, Leilei; Gao, Yuan; Reckmeier, Claas; He, Jin; Rogach, Andrey L.; Yao, Yan; Fan, Zhiyong

    2015-01-01

    Organometallic trihalide perovskites are promising materials for photovoltaic applications, which have demonstrated a rapid rise in photovoltaic performance in a short period of time. We report a facile one-step method to fabricate planar heterojunction perovskite solar cells by chemical vapor deposition (CVD), with a solar power conversion efficiency of up to 11.1%. We performed a systematic optimization of CVD parameters such as temperature and growth time to obtain high quality films of CH3NH3PbI3 and CH3NH3PbI3-xClx perovskite. Scanning electron microscopy and time resolved photoluminescence data showed that the perovskite films have a large grain size of more than 1 micrometer, and carrier life-times of 10 ns and 120 ns for CH3NH3PbI3 and CH3NH3PbI3-xClx, respectively. This is the first demonstration of a highly efficient perovskite solar cell using one step CVD and there is likely room for significant improvement of device efficiency. PMID:26392200

  17. Effects of Process Parameters on the Characteristics of Mixed-Halide Perovskite Solar Cells Fabricated by One-Step and Two-Step Sequential Coating.

    PubMed

    Ahmadian-Yazdi, Mohammad Reza; Zabihi, Fatemeh; Habibi, Mehran; Eslamian, Morteza

    2016-12-01

    In this paper, two-step sequential spin-dip and spin-spin coating, as well as one-step spin coating, methods are used to fabricate methylammonium lead mixed-halide perovskites to study the effect of process parameters, including the choice of the solvent, annealing temperature, spin velocity, and dipping time on the characteristics of the perovskite film. Our results show that using a mixture of DMF and DMSO, with volume ratio of 1:1, as the organic solvents for PbCl2 results in the best mixed-halide perovskite because of the effective coordination between DMSO and PbCl2. Surface dewetting due to two effects, i.e., crystallization and thin liquid film instability, is observed and discussed, where an intermediate spin velocity of about 4000 rpm is found suitable to suppress dewetting. The perovskite film fabricated using the one-step method followed by anti-solvent treatment shows the best perovskite conversion in XRD patterns, and the planar device fabricated using the same method exhibited the highest efficiency among the employed methods. The perovskite layer made by sequential spin-dip coating is found thicker with higher absorbance, but the device shows a lower efficiency because of the challenges associated with perovskite conversion in the sequential method. The one-step deposition method is found easier to control and more promising than the sequential deposition methods.

  18. Effects of Process Parameters on the Characteristics of Mixed-Halide Perovskite Solar Cells Fabricated by One-Step and Two-Step Sequential Coating

    NASA Astrophysics Data System (ADS)

    Ahmadian-Yazdi, Mohammad Reza; Zabihi, Fatemeh; Habibi, Mehran; Eslamian, Morteza

    2016-09-01

    In this paper, two-step sequential spin-dip and spin-spin coating, as well as one-step spin coating, methods are used to fabricate methylammonium lead mixed-halide perovskites to study the effect of process parameters, including the choice of the solvent, annealing temperature, spin velocity, and dipping time on the characteristics of the perovskite film. Our results show that using a mixture of DMF and DMSO, with volume ratio of 1:1, as the organic solvents for PbCl2 results in the best mixed-halide perovskite because of the effective coordination between DMSO and PbCl2. Surface dewetting due to two effects, i.e., crystallization and thin liquid film instability, is observed and discussed, where an intermediate spin velocity of about 4000 rpm is found suitable to suppress dewetting. The perovskite film fabricated using the one-step method followed by anti-solvent treatment shows the best perovskite conversion in XRD patterns, and the planar device fabricated using the same method exhibited the highest efficiency among the employed methods. The perovskite layer made by sequential spin-dip coating is found thicker with higher absorbance, but the device shows a lower efficiency because of the challenges associated with perovskite conversion in the sequential method. The one-step deposition method is found easier to control and more promising than the sequential deposition methods.

  19. Effects of Process Parameters on the Characteristics of Mixed-Halide Perovskite Solar Cells Fabricated by One-Step and Two-Step Sequential Coating.

    PubMed

    Ahmadian-Yazdi, Mohammad Reza; Zabihi, Fatemeh; Habibi, Mehran; Eslamian, Morteza

    2016-12-01

    In this paper, two-step sequential spin-dip and spin-spin coating, as well as one-step spin coating, methods are used to fabricate methylammonium lead mixed-halide perovskites to study the effect of process parameters, including the choice of the solvent, annealing temperature, spin velocity, and dipping time on the characteristics of the perovskite film. Our results show that using a mixture of DMF and DMSO, with volume ratio of 1:1, as the organic solvents for PbCl2 results in the best mixed-halide perovskite because of the effective coordination between DMSO and PbCl2. Surface dewetting due to two effects, i.e., crystallization and thin liquid film instability, is observed and discussed, where an intermediate spin velocity of about 4000 rpm is found suitable to suppress dewetting. The perovskite film fabricated using the one-step method followed by anti-solvent treatment shows the best perovskite conversion in XRD patterns, and the planar device fabricated using the same method exhibited the highest efficiency among the employed methods. The perovskite layer made by sequential spin-dip coating is found thicker with higher absorbance, but the device shows a lower efficiency because of the challenges associated with perovskite conversion in the sequential method. The one-step deposition method is found easier to control and more promising than the sequential deposition methods. PMID:27639581

  20. One-step Maskless Fabrication and Optical Characterization of Silicon Surfaces with Antireflective Properties and a White Color Appearance

    PubMed Central

    Schneider, Ling; Feidenhans’l, Nikolaj A.; Telecka, Agnieszka; Taboryski, Rafael J.

    2016-01-01

    We report a simple one-step maskless fabrication of inverted pyramids on silicon wafers by reactive ion etching. The fabricated surface structures exhibit excellent anti-reflective properties: The total reflectance of the nano inverted pyramids fabricated by our method can be as low as 12% without any anti-reflective layers, and down to only 0.33% with a silicon nitride coating. The results from angle resolved scattering measurements indicate that the existence of triple reflections is responsible for the reduced reflectance. The surfaces with the nano inverted pyramids also exhibit a distinct milky white color. PMID:27725703

  1. One-step Maskless Fabrication and Optical Characterization of Silicon Surfaces with Antireflective Properties and a White Color Appearance

    NASA Astrophysics Data System (ADS)

    Schneider, Ling; Feidenhans’L, Nikolaj A.; Telecka, Agnieszka; Taboryski, Rafael J.

    2016-10-01

    We report a simple one-step maskless fabrication of inverted pyramids on silicon wafers by reactive ion etching. The fabricated surface structures exhibit excellent anti-reflective properties: The total reflectance of the nano inverted pyramids fabricated by our method can be as low as 12% without any anti-reflective layers, and down to only 0.33% with a silicon nitride coating. The results from angle resolved scattering measurements indicate that the existence of triple reflections is responsible for the reduced reflectance. The surfaces with the nano inverted pyramids also exhibit a distinct milky white color.

  2. Fabrication of twisted nematic structure and vector grating cells by one-step exposure on photocrosslinkable polymer liquid crystals.

    PubMed

    Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2012-03-15

    We present a simple yet efficient method to automatically fabricate the twisted nematic structure by one-step exposure on an empty glass cell coated with photocrosslinkable polymer liquid crystal (PCLC) films. The resultant photoalignment directions of two substrates can be orthogonal to each other by controlling the difference between the exposure energy for upper and lower PCLC films and the twisted nematic (TN) structure can be automatically fabricated. The vector grating liquid crystalline cell with TN structure was also fabricated by means of a developed method, and the diffraction properties were well explained by the theoretical calculation on the basis of Jones calculus. PMID:22446243

  3. One-step electrodeposition process to fabricate corrosion-resistant superhydrophobic surface on magnesium alloy.

    PubMed

    Liu, Qin; Chen, Dexin; Kang, Zhixin

    2015-01-28

    A simple, one-step method has been developed to construct a superhydrophobic surface by electrodepositing Mg-Mn-Ce magnesium plate in an ethanol solution containing cerium nitrate hexahydrate and myristic acid. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were employed to characterize the surfaces. The shortest electrodeposition time to obtain a superhydrophobic surface was about 1 min, and the as-prepared superhydrophobic surfaces had a maximum contact angle of 159.8° and a sliding angle of less than 2°. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5 wt % aqueous solutions of NaCl, Na2SO4, NaClO3, and NaNO3. Besides, the chemical stability and mechanical durability of the as-prepared superhydrophobic surface were also examined. The presented method is rapid, low-cost, and environmentally friendly and thus should be of significant value for the industrial fabrication of anticorrosive superhydrophobic surfaces and should have a promising future in expanding the applications of magnesium alloys.

  4. One-step electrodeposition process to fabricate corrosion-resistant superhydrophobic surface on magnesium alloy.

    PubMed

    Liu, Qin; Chen, Dexin; Kang, Zhixin

    2015-01-28

    A simple, one-step method has been developed to construct a superhydrophobic surface by electrodepositing Mg-Mn-Ce magnesium plate in an ethanol solution containing cerium nitrate hexahydrate and myristic acid. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were employed to characterize the surfaces. The shortest electrodeposition time to obtain a superhydrophobic surface was about 1 min, and the as-prepared superhydrophobic surfaces had a maximum contact angle of 159.8° and a sliding angle of less than 2°. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5 wt % aqueous solutions of NaCl, Na2SO4, NaClO3, and NaNO3. Besides, the chemical stability and mechanical durability of the as-prepared superhydrophobic surface were also examined. The presented method is rapid, low-cost, and environmentally friendly and thus should be of significant value for the industrial fabrication of anticorrosive superhydrophobic surfaces and should have a promising future in expanding the applications of magnesium alloys. PMID:25559356

  5. A four-step approach to evaluate mixtures for consistency with dose addition.

    PubMed

    Hertzberg, Richard C; Pan, Yi; Li, Ruosha; Haber, Lynne T; Lyles, Robert H; Herr, David W; Moser, Virginia C; Simmons, Jane Ellen

    2013-11-16

    Mixture risk assessment is often hampered by the lack of dose-response information on the mixture being assessed, forcing reliance on component formulas such as dose addition. We present a four-step approach for evaluating chemical mixture data for consistency with dose addition for use in supporting a component based mixture risk assessment. Following the concepts in the U.S. EPA mixture risk guidance (U.S. EPA, 2000a,b), toxicological interaction for a defined mixture (all components known) is departure from a clearly articulated definition of component additivity. For the common approach of dose additivity, the EPA guidance identifies three desirable characteristics, foremost of which is that the component chemicals are toxicologically similar. The other two characteristics are empirical: the mixture components have toxic potencies that are fixed proportions of each other (throughout the dose range of interest), and the mixture dose term in the dose additive prediction formula, which we call the combined prediction model (CPM), can be represented by a linear combination of the component doses. A consequent property of the proportional toxic potencies is that the component chemicals must share a common dose-response model, where only the dose coefficients depend on the chemical components. A further consequence is that the mixture data must be described by the same mathematical function ("mixture model") as the components, but with a distinct coefficient for the total mixture dose. The mixture response is predicted from the component dose-response curves by using the dose additive CPM and the prediction is then compared with the observed mixture results. The four steps are to evaluate: (1) toxic proportionality by determining how well the CPM matches the single chemical models regarding mean and variance; (2) fit of the mixture model to the mixture data; (3) agreement between the mixture data and the CPM prediction; and (4) consistency between the CPM and the

  6. A four-step approach to evaluate mixtures for consistency with dose addition.

    PubMed

    Hertzberg, Richard C; Pan, Yi; Li, Ruosha; Haber, Lynne T; Lyles, Robert H; Herr, David W; Moser, Virginia C; Simmons, Jane Ellen

    2013-11-16

    Mixture risk assessment is often hampered by the lack of dose-response information on the mixture being assessed, forcing reliance on component formulas such as dose addition. We present a four-step approach for evaluating chemical mixture data for consistency with dose addition for use in supporting a component based mixture risk assessment. Following the concepts in the U.S. EPA mixture risk guidance (U.S. EPA, 2000a,b), toxicological interaction for a defined mixture (all components known) is departure from a clearly articulated definition of component additivity. For the common approach of dose additivity, the EPA guidance identifies three desirable characteristics, foremost of which is that the component chemicals are toxicologically similar. The other two characteristics are empirical: the mixture components have toxic potencies that are fixed proportions of each other (throughout the dose range of interest), and the mixture dose term in the dose additive prediction formula, which we call the combined prediction model (CPM), can be represented by a linear combination of the component doses. A consequent property of the proportional toxic potencies is that the component chemicals must share a common dose-response model, where only the dose coefficients depend on the chemical components. A further consequence is that the mixture data must be described by the same mathematical function ("mixture model") as the components, but with a distinct coefficient for the total mixture dose. The mixture response is predicted from the component dose-response curves by using the dose additive CPM and the prediction is then compared with the observed mixture results. The four steps are to evaluate: (1) toxic proportionality by determining how well the CPM matches the single chemical models regarding mean and variance; (2) fit of the mixture model to the mixture data; (3) agreement between the mixture data and the CPM prediction; and (4) consistency between the CPM and the

  7. SEMICONDUCTOR TECHNOLOGY: Reduction of proximity effect in fabricating nanometer-spaced nanopillars by two-step exposure

    NASA Astrophysics Data System (ADS)

    Yang, Zhang; Renping, Zhang; Weihua, Han; Jian, Liu; Xiang, Yang; Ying, Wang; Chian Chiu, Li; Fuhua, Yang

    2009-11-01

    A two-step exposure method to effectively reduce the proximity effect in fabricating nanometer-spaced nanopillars is presented. In this method, nanopillar patterns on poly-methylmethacrylate (PMMA) were partly cross-linked in the first-step exposure. After development, PMMA between nanopillar patterns was removed, and hence the proximity effect would not take place there in the subsequent exposure. In the second-step exposure, PMMA masks were completely cross-linked to achieve good resistance in inductively coupled plasma etching. Accurate pattern transfer of rows of nanopillars with spacing down to 40 nm was realized on a silicon-on-insulator substrate.

  8. A Novel One-Step Fabricated, Droplet-Based Electrochemical Sensor for Facile Biochemical Assays.

    PubMed

    Yao, Yong; Zhang, Chunsun

    2016-01-01

    A simple, novel concept for the one-step fabrication of a low-cost, easy-to-use droplet-based electrochemical (EC) sensor is described, in which the EC reagents are contained in a droplet and the droplet assay is operated on a simple planar surface instead of in a complicated closed channel/chamber. In combination with an elegant carbon electrode configuration, screen-printed on a widely available polyethylene terephthalate (PET) substrate, the developed sensor exhibits a stable solution-restriction capacity and acceptable EC response, and thus can be used directly for the detection of different analytes (including ascorbic acid (AA), copper ions (Cu(2+)), 2'-deoxyguanosine 5'-triphosphate (dGTP) and ferulic acid (FA)), without any pretreatment. The obtained, acceptable linear ranges/detection limits for AA, Cu(2+), dGTP and FA are 0.5-10/0.415 mM, (0.0157-0.1574 and 0.1574-1.5736)/0.011 mM, 0.01-0.1/0.008 mM and 0.0257-0.515/0.024 mM, respectively. Finally, the utility of the droplet-based EC sensor was demonstrated for the determination of AA in two commercial beverages, and of Cu(2+) in two water samples, with reliable recovery and good stability. The applicability of the droplet-based sensor demonstrates that the proposed EC strategy is potentially a cost-effective solution for a series of biochemical sensing applications in public health, environmental monitoring, and the developing world. PMID:27527176

  9. Fabrication of parylene channels embedded in silicon using a single parylene deposition step

    NASA Astrophysics Data System (ADS)

    Tolstosheeva, Elena; Pimentel, João. V.; Schander, Andreas; Kempen, Ludger; Vellekoop, Michael; Lang, Walter

    2015-06-01

    In-situ integration of microfluidic channels into the microfabrication process flow of implantable microsystems is desirable, for example to enable efficient drug delivery. We propose a fabrication method for such microfluidic channels using parylene C, a biocompatible material whose inert nature favours water flow. A single deposition of parylene C enabled monolithical integration of fully-sealed micro-channels in a silicon substrate. The channel geometry was predefined by etching 100 μm-deep grooves into a silicon substrate. A PVC foil was fixed manually on the wafer and served as a top-cover for the grooves. The wafers were coated with the adhesion promoter AdPro Poly® and a 15 μm-thick parylene C film was deposited conformally into the grooves-foil enclosed space. The outgasing nature of the PVC foil hindered the adhesion of parylene C, allowing the foil to be peeled off easily from the parylene surface. The functionality of the fully-sealed parylene channels, embedded in the silicon wafer, was verified by injecting DI water with dispersed polystyrene microbeads (diameter 6 μm): the polystyrene beads were successfully transported along the channel. Further, a fully-sealed parylene chamber remained leak-tight throughout a stepwise application of hydrostatic pressures from 0.2 to 3.0 bar (15 s step-interval). In short, our parylene channels are: (1) suitable for microsystem drug-delivery; (2) in-situ enclosed hollow spaces embedded in the silicon substrate, realized with a single parylene deposition; (3) intact at hydrostatic pressures up to 3 bar.

  10. A Novel One-Step Fabricated, Droplet-Based Electrochemical Sensor for Facile Biochemical Assays

    PubMed Central

    Yao, Yong; Zhang, Chunsun

    2016-01-01

    A simple, novel concept for the one-step fabrication of a low-cost, easy-to-use droplet-based electrochemical (EC) sensor is described, in which the EC reagents are contained in a droplet and the droplet assay is operated on a simple planar surface instead of in a complicated closed channel/chamber. In combination with an elegant carbon electrode configuration, screen-printed on a widely available polyethylene terephthalate (PET) substrate, the developed sensor exhibits a stable solution-restriction capacity and acceptable EC response, and thus can be used directly for the detection of different analytes (including ascorbic acid (AA), copper ions (Cu2+), 2′-deoxyguanosine 5′-triphosphate (dGTP) and ferulic acid (FA)), without any pretreatment. The obtained, acceptable linear ranges/detection limits for AA, Cu2+, dGTP and FA are 0.5–10/0.415 mM, (0.0157–0.1574 and 0.1574–1.5736)/0.011 mM, 0.01–0.1/0.008 mM and 0.0257–0.515/0.024 mM, respectively. Finally, the utility of the droplet-based EC sensor was demonstrated for the determination of AA in two commercial beverages, and of Cu2+ in two water samples, with reliable recovery and good stability. The applicability of the droplet-based sensor demonstrates that the proposed EC strategy is potentially a cost-effective solution for a series of biochemical sensing applications in public health, environmental monitoring, and the developing world. PMID:27527176

  11. An evaluation of dimensional accuracy of one-step and two-step impression technique using addition silicone impression material: an in vitro study.

    PubMed

    Pande, Neelam A; Parkhedkar, R D

    2013-09-01

    The study is aimed to evaluate the dimensional accuracy, the effect of undercut of two different configurations and the elastic recovery of addition silicone impression material assessed indirectly, by measuring the dimensions on stone models recorded from the impression of the master model, using one-step and two-step impression technique, for addition silicone impression materials. Measurements are taken to evaluate horizontal or linear and vertical dimensional changes, of the abutment V and abutment C from the stainless steel model. Heavy body/light body material is used for making one-step impression technique in a custom tray. Putty/light body is used for taking two-step technique in a stock metal tray. Improved die stone is used for pouring the impression. The different 11 locations on the dies produced by two different techniques are measured microscopically on image analyzer and compared with those of stainless steel model. Anova test was applied to test the differences of mean values of inter and intra abutment measurements, to calculate p value. Unpaired t test was applied to calculate t value. Results showed less deviation of stone models produced by one-step technique from stainless steel model, whereas the deviation of stone models produced by two-step is comparatively more. (p < 0.01). This difference of deviation is significantly less in one-step as compared to two-step technique. One-step is sufficiently dimensionally accurate than two-step technique in conjunction with addition silicone impression material. They have the best elastic recovery from the two undercut configurations.

  12. A rapid one-step fabrication of patternable superhydrophobic surfaces driven by Marangoni instability.

    PubMed

    Kang, Sung-Min; Hwang, Sora; Jin, Si-Hyung; Choi, Chang-Hyung; Kim, Jongmin; Park, Bum Jun; Lee, Daeyeon; Lee, Chang-Soo

    2014-03-18

    We present a facile and inexpensive approach without any fluorinated chemistry to create superhydrophobic surface with exceptional liquid repellency, transportation of oil, selective capture of oil, optical bar code, and self-cleaning. Here we show experimentally that the control of evaporation is important and can be used to form superhydrophobic surface driven by Marangoni instability: the method involves in-situ photopolymerization in the presence of a volatile solvent and porous PDMS cover to afford superhydrophobic surfaces with the desired combination of micro- and nanoscale roughness. The porous PDMS cover significantly affects Marangoni convection of coating fluid, inducing composition gradients at the same time. In addition, the change of concentration of ethanol is able to produce versatile surfaces from hydrophilic to superhydrophobic and as a consequence to determine contact angles as well as roughness factors. In conclusion, the control of evaporation under the polymerization provides a convenient parameter to fabricate the superhydrophobic surface, without application of fluorinated chemistry and the elegant nanofabrication technique.

  13. Synchrotron X-ray CT characterization of titanium parts fabricated by additive manufacturing. Part I. Morphology.

    PubMed

    Scarlett, Nicola Vivienne Yorke; Tyson, Peter; Fraser, Darren; Mayo, Sheridan; Maksimenko, Anton

    2016-07-01

    Synchrotron X-ray tomography has been applied to the study of titanium parts fabricated by additive manufacturing (AM). The AM method employed here was the Arcam EBM(®) (electron beam melting) process which uses powdered titanium alloy, Ti64 (Ti alloy with approximately 6%Al and 4%V), as the feed and an electron beam for the sintering/welding. The experiment was conducted on the Imaging and Medical Beamline of the Australian Synchrotron. Samples were chosen to examine the effect of build direction and complexity of design on the surface morphology and final dimensions of the piece.

  14. Synchrotron X-ray CT characterization of titanium parts fabricated by additive manufacturing. Part I. Morphology.

    PubMed

    Scarlett, Nicola Vivienne Yorke; Tyson, Peter; Fraser, Darren; Mayo, Sheridan; Maksimenko, Anton

    2016-07-01

    Synchrotron X-ray tomography has been applied to the study of titanium parts fabricated by additive manufacturing (AM). The AM method employed here was the Arcam EBM(®) (electron beam melting) process which uses powdered titanium alloy, Ti64 (Ti alloy with approximately 6%Al and 4%V), as the feed and an electron beam for the sintering/welding. The experiment was conducted on the Imaging and Medical Beamline of the Australian Synchrotron. Samples were chosen to examine the effect of build direction and complexity of design on the surface morphology and final dimensions of the piece. PMID:27359150

  15. Double-Step Image Superimposition Technique for Fabricating a Drilling Guide to Access the Abutment Screw in Implant Prostheses.

    PubMed

    Mai, Hang-Nga; Kim, Kyung-Rok; Lee, Du-Hyeong

    2016-01-01

    Limited retrievability is a major disadvantage of cement-retained implant restorations. Despite great progress in locating the abutment screw within crowns, the existing techniques are based on prior data or prefabricated devices and require significant work. This study introduces a new procedure for fabricating a guide template to drill a screw access hole using a double-step superimposition technique that incorporates intraoral optical scanning, cone beam computed tomography, and dental design software. The double-step superimposition technique with computer-aided design/computer-assisted manufacturing technology can enhance the convenience and accuracy of drilling the screw-access hole. PMID:27479352

  16. Thermal imaging for assessment of electron-beam freeform fabrication (EBF3) additive manufacturing deposits

    NASA Astrophysics Data System (ADS)

    Zalameda, Joseph N.; Burke, Eric R.; Hafley, Robert A.; Taminger, Karen M.; Domack, Christopher S.; Brewer, Amy; Martin, Richard E.

    2013-05-01

    Additive manufacturing is a rapidly growing field where 3-dimensional parts can be produced layer by layer. NASA's electron beam freeform fabrication (EBF3) technology is being evaluated to manufacture metallic parts in a space environment. The benefits of EBF3 technology are weight savings to support space missions, rapid prototyping in a zero gravity environment, and improved vehicle readiness. The EBF3 system is composed of 3 main components: electron beam gun, multi-axis position system, and metallic wire feeder. The electron beam is used to melt the wire and the multi-axis positioning system is used to build the part layer by layer. To insure a quality deposit, a near infrared (NIR) camera is used to image the melt pool and solidification areas. This paper describes the calibration and application of a NIR camera for temperature measurement. In addition, image processing techniques are presented for deposit assessment metrics.

  17. Fatigue Life of Titanium Alloys Fabricated by Additive Layer Manufacturing Techniques for Dental Implants

    NASA Astrophysics Data System (ADS)

    Chan, Kwai S.; Koike, Marie; Mason, Robert L.; Okabe, Toru

    2013-02-01

    Additive layer deposition techniques such as electron beam melting (EBM) and laser beam melting (LBM) have been utilized to fabricate rectangular plates of Ti-6Al-4V with extra low interstitial (ELI) contents. The layer-by-layer deposition techniques resulted in plates that have different surface finishes which can impact significantly on the fatigue life by providing potential sites for fatigue cracks to initiate. The fatigue life of Ti-6Al-4V ELI alloys fabricated by EBM and LBM deposition techniques was investigated by three-point testing of rectangular beams of as-fabricated and electro-discharge machined surfaces under stress-controlled conditions at 10 Hz until complete fracture. Fatigue life tests were also performed on rolled plates of Ti-6Al-4V ELI, regular Ti-6Al-4V, and CP Ti as controls. Fatigue surfaces were characterized by scanning electron microscopy to identify the crack initiation site in the various types of specimen surfaces. The fatigue life data were analyzed statistically using both analysis of variance techniques and the Kaplan-Meier survival analysis method with the Gehan-Breslow test. The results indicate that the LBM Ti-6Al-4V ELI material exhibits a longer fatigue life than the EBM counterpart and CP Ti, but a shorter fatigue life compared to rolled Ti-6Al-4V ELI. The difference in the fatigue life behavior may be largely attributed to the presence of rough surface features that act as fatigue crack initiation sites in the EBM material.

  18. Surface Modified Particles By Multi-Step Michael-Type Addition And Process For The Preparation Thereof

    DOEpatents

    Cook, Ronald Lee; Elliott, Brian John; Luebben, Silvia DeVito; Myers, Andrew William; Smith, Bryan Matthew

    2005-05-03

    A new class of surface modified particles and a multi-step Michael-type addition surface modification process for the preparation of the same is provided. The multi-step Michael-type addition surface modification process involves two or more reactions to compatibilize particles with various host systems and/or to provide the particles with particular chemical reactivities. The initial step comprises the attachment of a small organic compound to the surface of the inorganic particle. The subsequent steps attach additional compounds to the previously attached organic compounds through reactive organic linking groups. Specifically, these reactive groups are activated carbon—carbon pi bonds and carbon and non-carbon nucleophiles that react via Michael or Michael-type additions.

  19. Deformation Mechanisms in NiTi-Al Composites Fabricated by Ultrasonic Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Chen, Xiang; Hehr, Adam; Dapino, Marcelo J.; Anderson, Peter M.

    2015-09-01

    Thermally active NiTi shape memory alloy (SMA) fibers can be used to tune or tailor the effective coefficient of thermal expansion (CTE) of a metallic matrix composite. In this paper, a novel NiTi-Al composite is fabricated using ultrasonic additive manufacturing (UAM). A combined experimental-simulation approach is used to develop and validate a microstructurally based finite element model of the composite. The simulations are able to closely reproduce the macroscopic strain versus temperature cyclic response, including initial transient effects in the first cycle. They also show that the composite CTE is minimized if the austenite texture in the SMA wires is <001>B2, that a fiber aspect ratio >10 maximizes fiber efficiency, and that the UAM process may reduce hysteresis in embedded SMA wires.

  20. One-step polymer screen-printing for microfluidic paper-based analytical device (μPAD) fabrication.

    PubMed

    Sameenoi, Yupaporn; Nongkai, Piyaporn Na; Nouanthavong, Souksanh; Henry, Charles S; Nacapricha, Duangjai

    2014-12-21

    We report a simple, low-cost, one-step fabrication method for microfluidic paper-based analytical devices (μPAD) using only polystyrene and a patterned screen. The polystyrene solution applied through the screen penetrates through the paper, forming a three-dimensional hydrophobic barrier, defining a hydrophilic analysis zone. The optimal polystyrene concentration and paper types were first investigated. Adjusting polystyrene concentration allows for various types of paper to be used for successful device fabrication. Using an optimized polystyrene concentration with Whatman#4 filter paper, a linear relationship was found to exist between the design width and the printed width. The smallest hydrophilic channel and hydrophobic barrier that can be obtained are 670 ± 50 μm and 380 ± 40 μm, respectively. High device-to-device fabrication reproducibility was achieved yielding a relative standard deviation (%RSD) in the range of 1.12-2.54% (n = 64) of the measured diameter of the well-shaped fabricated test zones with a designed diameter of 5 and 7 mm. To demonstrate the significance of the fabricated μPAD, distance-based and well-based paper devices were constructed for the analysis of H2O2 and antioxidant activity, respectively. The analysis of H2O2 in real samples using distance-based measurement with CeO2 nanoparticles as the colorimetric agent produced the same results at 95% confidence level, as those obtained using KMnO4 titration. A proof-of-concept antioxidant activity determination based on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was also demonstrated. The results verify that the polymer screen-printing method can be used as an alternative method for μPAD fabrication. PMID:25360590

  1. Additional efficient computation of branched nerve equations: adaptive time step and ideal voltage clamp.

    PubMed

    Borg-Graham, L J

    2000-01-01

    Various improvements are described for the simulation of biophysically and anatomically detailed compartmental models of single neurons and networks of neurons. These include adaptive time-step integration and a reordering of the circuit matrix to allow ideal voltage clamp of arbitrary nodes. We demonstrate how the adaptive time-step method can give equivalent accuracy as a fixed time-step method for typical current clamp simulation protocols, with about a 2.5 reduction in runtime. The ideal voltage clamp method is shown to be more stable than the nonideal case, in particular when used with the adaptive time-step method. Simulation results are presented using the Surf-Hippo Neuron Simulation System, a public domain object-oriented simulator written in Lisp. PMID:10809013

  2. Virus elimination during the purification of monoclonal antibodies by column chromatography and additional steps.

    PubMed

    Roberts, Peter L

    2014-01-01

    The theoretical potential for virus transmission by monoclonal antibody based therapeutic products has led to the inclusion of appropriate virus reduction steps. In this study, virus elimination by the chromatographic steps used during the purification process for two (IgG-1 & -3) monoclonal antibodies (MAbs) have been investigated. Both the Protein G (>7log) and ion-exchange (5 log) chromatography steps were very effective for eliminating both enveloped and non-enveloped viruses over the life-time of the chromatographic gel. However, the contribution made by the final gel filtration step was more limited, i.e., 3 log. Because these chromatographic columns were recycled between uses, the effectiveness of the column sanitization procedures (guanidinium chloride for protein G or NaOH for ion-exchange) were tested. By evaluating standard column runs immediately after each virus spiked run, it was possible to directly confirm that there was no cross contamination with virus between column runs (guanidinium chloride or NaOH). To further ensure the virus safety of the product, two specific virus elimination steps have also been included in the process. A solvent/detergent step based on 1% triton X-100 rapidly inactivating a range of enveloped viruses by >6 log inactivation within 1 min of a 60 min treatment time. Virus removal by virus filtration step was also confirmed to be effective for those viruses of about 50 nm or greater. In conclusion, the combination of these multiple steps ensures a high margin of virus safety for this purification process.

  3. Fabrication and assembly of MEMS accelerometer-based heart monitoring device with simplified, one step placement.

    PubMed

    Tjulkins, Fjodors; Nguyen, Anh-Tuan Thai; Andreassen, Erik; Aasmundtveit, Knut; Hoivik, Nils; Hoff, Lars; Halvorsen, Per Steinar; Grymyr, Ole-Johannes; Imenes, Kristin

    2015-01-01

    An accelerometer-based heart monitoring system has been developed for real-time evaluation of heart wall movement. In this paper, assembly and fabrication of an improved device is presented along with system characterization and test data from an animal experiment. The new device is smaller and has simplified the implantation procedure compared to earlier prototypes. Leakage current recordings were well below those set by the corresponding standards. PMID:25429874

  4. Interfacial shear strength estimates of NiTi-Al matrix composites fabricated via ultrasonic additive manufacturing

    NASA Astrophysics Data System (ADS)

    Hehr, Adam; Pritchard, Joshua; Dapino, Marcelo J.

    2014-03-01

    The purpose of this study is to understand and improve the interfacial shear strength of metal matrix composites fabricated via very high power (VHP) ultrasonic additive manufacturing (UAM). VHP-UAM NiTi-Al composites have shown a dramatic decrease in thermal expansion compared to Al, yet thermal blocking stresses developed during thermal cycling have been found to degrade and eventually cause interface failure. Consequently, to improve understanding of the interface and guide the development of stronger NiTi- Al composites, the interface strength was investigated through the use of single ber pullout tests. It was found that the matrix yielded prior to the interface breaking since adhered aluminum was consistently observed on all pullout samples. Additionally, measured pullout loads were utilized as an input to a nite element model for stress and shear lag analysis, which, in turn showed that the Al matrix experienced a peak shear stress near 230 MPa. This stress is above the Al matrix's ultimate shear strength of 150-200 MPa, thus this large stress corroborates with matrix failure observed during testing. The in uence of various ber surface treatments on bond mechanisms was also studied with scanning electron microscopy and energy dispersive X-ray spectroscopy.

  5. One-step fabrication of free-standing flexible membranes reinforced with self-assembled arrays of carbon nanotubes

    SciTech Connect

    Grilli, S.; Coppola, S.; Vespini, V.; Pagliarulo, V.; Ferraro, P.; Nasti, G.; Carfagna, C.

    2014-10-13

    Here, we report on a single step approach for fabricating free-standing polymer membranes reinforced with arrayed self-assembled carbon nanotubes (CNTs). The CNTs are self-assembled spontaneously by electrode-free DC dielectrophoresis based on surface charge templates. The electrical charge template is generated through the pyroelectric effect onto periodically poled lithium niobate ferroelectric crystals. A thermal stimulus enables simultaneously the self-assembly of the CNTs and the cross-linking of the host polymer. Examples of thin polydimethylsiloxane membranes reinforced with CNT patterns are shown.

  6. One-step fabrication of intense red fluorescent gold nanoclusters and their application in cancer cell imaging

    NASA Astrophysics Data System (ADS)

    Bian, Pingping; Zhou, Jing; Liu, Yueying; Ma, Zhanfang

    2013-06-01

    A one-step method for successfully fabrication of water-soluble and alkanethiol-stabilized Au nanoclusters (NCs) was demonstrated. The novel and facile method was based on simply placing histidine (His), HAuCl4 and 11-mercaptoundcanoic acid (MUA) together at room temperature. The resulting Au NCs were exclusively composed of Au17MUA4His22 (AMH), as demonstrated by the photoluminescence, UV-Vis absorption, electrospray ionization mass and X-ray photoelectron spectroscopy. AMH exhibited intense red fluorescence (λem = 600 nm), a long fluorescence lifetime (7.11 μs), considerable stability, and a large Stoke's shift (320 nm). Based on the excellent properties of the AMH, cell experiments were conducted. Cytotoxicity studies showed that the Au NCs exhibited negligible effects in altering cell proliferation or triggering apoptosis. Cancer cell imaging of HeLa cell lines indicated that the obtained AMH could serve as a promising fluorescent bioprobe for bioimaging. This strategy, based on the one-step method, may offer a novel approach to fabricate other water-soluble and alkanethiol-stabilized metal nanoclusters for application in biolabelling and bioimaging.A one-step method for successfully fabrication of water-soluble and alkanethiol-stabilized Au nanoclusters (NCs) was demonstrated. The novel and facile method was based on simply placing histidine (His), HAuCl4 and 11-mercaptoundcanoic acid (MUA) together at room temperature. The resulting Au NCs were exclusively composed of Au17MUA4His22 (AMH), as demonstrated by the photoluminescence, UV-Vis absorption, electrospray ionization mass and X-ray photoelectron spectroscopy. AMH exhibited intense red fluorescence (λem = 600 nm), a long fluorescence lifetime (7.11 μs), considerable stability, and a large Stoke's shift (320 nm). Based on the excellent properties of the AMH, cell experiments were conducted. Cytotoxicity studies showed that the Au NCs exhibited negligible effects in altering cell proliferation or

  7. One-step process for the fabrication of superhydrophobic surfaces with easy repairability

    NASA Astrophysics Data System (ADS)

    Li, Jian; Wan, Hongqi; Ye, Yinping; Zhou, Huidi; Chen, Jianmin

    2012-01-01

    A simple technique for fabrication of superhydrophobic surfaces was developed by spraying copper stearate suspension on various substrates. The copper stearate suspension is prepared by the reaction of copper acetate and stearic acid in ethanol solution. The as-prepared surfaces exhibit both superhydrophobicity and self-cleaning properties. When the superhydrophobic surfaces were destroyed, the damaged surfaces could be easily repaired by spraying the copper stearate suspension on the wrecked surfaces again, and the superhydrophobicity of the surfaces was regenerated at the same time.

  8. Dual metamaterial structures generated from an one-step fabrication using stencil lithography

    NASA Astrophysics Data System (ADS)

    Leong, Eunice S. P.; Deng, J.; Liu, Y. J.; Teng, J. H.

    2014-09-01

    The flexibility to deposit metallic structures on any substrates without the need of lift-off or etching process are the main reasons for the recent popularity of using stencil lithography for plasmonic applications. In this work, we fabricate nanoholes on a Si3N4 membrane and deposit metal-dielectric layers and such approach allows us to have a perforated fishnet metamaterial structure on the membrane as well as its complementary pillar structure on a quartz substrate. We then studied and compared their optical properties from both experiment and simulation results.

  9. One-step process to fabrication of transparent superhydrophobic SiO2 paper

    NASA Astrophysics Data System (ADS)

    Li, Jian; Wan, Hongqi; Ye, Yinping; Zhou, Huidi; Chen, Jianmin

    2012-11-01

    A simple technique for fabrication of superhydrophobic SiO2 paper was developed by spraying hydrophobic SiO2 nanoparticles suspension on paper substrate. The hydrophobic SiO2 nanoparticles were prepared by imparting octadecyltrichloro group on SiO2 nanoparticles. The as-prepared superhydrophobic SiO2 paper exhibted high water contact angle and low water sliding angle. Futhermore, the obtained superhydrophobic SiO2 paper was found to be highly transparent and the visibility of the character on the paper was not changed after spray-coating the hydrophobic SiO2 nanoparticles.

  10. Single-step fabrication of quantum funnels via centrifugal colloidal casting of nanoparticle films

    PubMed Central

    Kim, Jin Young; Adinolfi, Valerio; Sutherland, Brandon R.; Voznyy, Oleksandr; Kwon, S. Joon; Kim, Tae Wu; Kim, Jeongho; Ihee, Hyotcherl; Kemp, Kyle; Adachi, Michael; Yuan, Mingjian; Kramer, Illan; Zhitomirsky, David; Hoogland, Sjoerd; Sargent, Edward H.

    2015-01-01

    Centrifugal casting of composites and ceramics has been widely employed to improve the mechanical and thermal properties of functional materials. This powerful method has yet to be deployed in the context of nanoparticles—yet size–effect tuning of quantum dots is among their most distinctive and application-relevant features. Here we report the first gradient nanoparticle films to be constructed in a single step. By creating a stable colloid of nanoparticles that are capped with electronic-conduction-compatible ligands we were able to leverage centrifugal casting for thin-films devices. This new method, termed centrifugal colloidal casting, is demonstrated to form films in a bandgap-ordered manner with efficient carrier funnelling towards the lowest energy layer. We constructed the first quantum-gradient photodiode to be formed in a single deposition step and, as a result of the gradient-enhanced electric field, experimentally measured the highest normalized detectivity of any colloidal quantum dot photodetector. PMID:26165185

  11. Step and flash imprint lithography template fabrication for emerging market applications

    NASA Astrophysics Data System (ADS)

    Resnick, Douglas J.; Schmid, Gerard; Miller, Mike; Doyle, Gary; Jones, Chris; LaBrake, Dwayne

    2007-05-01

    The Step and Flash Imprint Lithography (S-FIL TM) process uses field-to-field drop dispensing of UV curable liquids for step and repeat patterning for applications where high-resolution mix-and-match overlay is desired. Several applications, including patterned media, photonic crystals and wire grid polarizers, are better served by a patterning process that prints the full wafer since alignment requirements are not so stringent. In this paper, a methodology for creating high resolution thin templates for full wafer (or disk) imprinting is described. The methods have been applied toward the imprinting of both photonic crystal and patterned media devices using a large area printing tool developed around the S-FIL process.

  12. Single-step fabrication of quantum funnels via centrifugal colloidal casting of nanoparticle films.

    PubMed

    Kim, Jin Young; Adinolfi, Valerio; Sutherland, Brandon R; Voznyy, Oleksandr; Kwon, S Joon; Kim, Tae Wu; Kim, Jeongho; Ihee, Hyotcherl; Kemp, Kyle; Adachi, Michael; Yuan, Mingjian; Kramer, Illan; Zhitomirsky, David; Hoogland, Sjoerd; Sargent, Edward H

    2015-07-13

    Centrifugal casting of composites and ceramics has been widely employed to improve the mechanical and thermal properties of functional materials. This powerful method has yet to be deployed in the context of nanoparticles--yet size-effect tuning of quantum dots is among their most distinctive and application-relevant features. Here we report the first gradient nanoparticle films to be constructed in a single step. By creating a stable colloid of nanoparticles that are capped with electronic-conduction-compatible ligands we were able to leverage centrifugal casting for thin-films devices. This new method, termed centrifugal colloidal casting, is demonstrated to form films in a bandgap-ordered manner with efficient carrier funnelling towards the lowest energy layer. We constructed the first quantum-gradient photodiode to be formed in a single deposition step and, as a result of the gradient-enhanced electric field, experimentally measured the highest normalized detectivity of any colloidal quantum dot photodetector.

  13. Low-cost one-step fabrication of superhydrophobic surface on Al alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Youfa; Wu, Jie; Yu, Xinquan; Wu, Hao

    2011-07-01

    A stable superhydrophobicity on aluminum alloy has been rendered by a low-cost one-step method, simply immersing the substrates in a solution containing hydrochloric acid and fatty acid molecules. The formation mechanism of such a surface was proposed by SEM morphology and EDS results. The resulting surface shows superhydrophobicity and low adhesion. This low cost and facile process provides a real feasible avenue for large-scale production of superhydrophobic surfaces.

  14. Facile fabrication of nano-structured silica hybrid film with superhydrophobicity by one-step VAFS approach

    NASA Astrophysics Data System (ADS)

    Jia, Yi; Yue, Renliang; Liu, Gang; Yang, Jie; Ni, Yong; Wu, Xiaofeng; Chen, Yunfa

    2013-01-01

    Here we report a novel one-step vapor-fed aerosol flame synthesis (VAFS) method to attain silica hybrid film with superhydrophobicity on normal glass and other engineering material substrates using hexamethyldisiloxane (HMDSO) as precursor. The deposited nano-structured silica films represent excellent superhydrophobicity with contact angle larger than 150° and sliding angle below 5°, without any surface modification or other post treatments. SEM photographs proved that flame-made SiO2 nanoparticles formed dual-scale surface roughness on the substrates. It was confirmed by FTIR and XPS that the in situ formed organic fragments on the particle surface as species like (CH3)xSiO2-x/2 (x = 1, 2, 3) which progressively lowered the surface energy of fabricated films. Thus, these combined dual-scale roughness and lowered surface energy cooperatively produced superhydrophobic films. IR camera had been used to monitor the real-time flame temperature. It is found that the inert dilution gas inflow played a critical role in attaining superhydrophobicity due to its cooling and anti-oxidation effect. This method is facile and scalable for diverse substrates, without any requirement of complex equipments and multiple processing steps. It may contribute to the industrial fabrication of superhydrophobic films.

  15. Single-step direct fabrication of pillar-on-pore hybrid nanostructures in anodizing aluminum for superior superhydrophobic efficiency.

    PubMed

    Jeong, Chanyoung; Choi, Chang-Hwan

    2012-02-01

    Conventional electrochemical anodizing processes of metals such as aluminum typically produce planar and homogeneous nanopore structures. If hydrophobically treated, such 2D planar and interconnected pore structures typically result in lower contact angle and larger contact angle hysteresis than 3D disconnected pillar structures and, hence, exhibit inferior superhydrophobic efficiency. In this study, we demonstrate for the first time that the anodizing parameters can be engineered to design novel pillar-on-pore (POP) hybrid nanostructures directly in a simple one-step fabrication process so that superior surface superhydrophobicity can also be realized effectively from the electrochemical anodization process. On the basis of the characteristic of forming a self-ordered porous morphology in a hexagonal array, the modulation of anodizing voltage and duration enabled the formulation of the hybrid-type nanostructures having controlled pillar morphology on top of a porous layer in both mild and hard anodization modes. The hybrid nanostructures of the anodized metal oxide layer initially enhanced the surface hydrophilicity significantly (i.e., superhydrophilic). However, after a hydrophobic monolayer coating, such hybrid nanostructures then showed superior superhydrophobic nonwetting properties not attainable by the plain nanoporous surfaces produced by conventional anodization conditions. The well-regulated anodization process suggests that electrochemical anodizing can expand its usefulness and efficacy to render various metallic substrates with great superhydrophilicity or -hydrophobicity by directly realizing pillar-like structures on top of a self-ordered nanoporous array through a simple one-step fabrication procedure.

  16. Microwave Enabled One-Pot, One-Step Fabrication and Nitrogen Doping of Holey Graphene Oxide for Catalytic Applications.

    PubMed

    Patel, Mehulkumar; Feng, Wenchun; Savaram, Keerthi; Khoshi, M Reza; Huang, Ruiming; Sun, Jing; Rabie, Emann; Flach, Carol; Mendelsohn, Richard; Garfunkel, Eric; He, Huixin

    2015-07-15

    The unique properties of a holey graphene sheet, referred to as a graphene sheet with nanoholes in its basal plane, lead to wide range of applications that cannot be achieved by its nonporous counterpart. However, the large-scale solution-based production requires graphene oxide (GO) or reduced GO (rGO) as the starting materials, which take hours to days for fabrication. Here, an unexpected discovery that GO with or without holes can be controllably, directly, and rapidly (tens of seconds) fabricated from graphite powder via a one-step-one-pot microwave assisted reaction with a production yield of 120 wt% of graphite is reported. Furthermore, a fast and low temperature approach is developed for simultaneous nitrogen (N) doping and reduction of GO sheets. The N-doped holey rGO sheets demonstrate remarkable electrocatalytic capabilities for the electrochemical oxygen reduction reaction. The existence of the nanoholes provides a "short cut" for efficient mass transport and dramatically increases edges and surface area, therefore, creates more catalytic centers. The capability of rapid fabrication and N-doping as well as reduction of holey GO can lead to development of an efficient catalyst that can replace previous coin metals for energy generation and storage, such as fuel cells and metal-air batteries. PMID:25683019

  17. Microwave Enabled One-Pot, One-Step Fabrication and Nitrogen Doping of Holey Graphene Oxide for Catalytic Applications.

    PubMed

    Patel, Mehulkumar; Feng, Wenchun; Savaram, Keerthi; Khoshi, M Reza; Huang, Ruiming; Sun, Jing; Rabie, Emann; Flach, Carol; Mendelsohn, Richard; Garfunkel, Eric; He, Huixin

    2015-07-15

    The unique properties of a holey graphene sheet, referred to as a graphene sheet with nanoholes in its basal plane, lead to wide range of applications that cannot be achieved by its nonporous counterpart. However, the large-scale solution-based production requires graphene oxide (GO) or reduced GO (rGO) as the starting materials, which take hours to days for fabrication. Here, an unexpected discovery that GO with or without holes can be controllably, directly, and rapidly (tens of seconds) fabricated from graphite powder via a one-step-one-pot microwave assisted reaction with a production yield of 120 wt% of graphite is reported. Furthermore, a fast and low temperature approach is developed for simultaneous nitrogen (N) doping and reduction of GO sheets. The N-doped holey rGO sheets demonstrate remarkable electrocatalytic capabilities for the electrochemical oxygen reduction reaction. The existence of the nanoholes provides a "short cut" for efficient mass transport and dramatically increases edges and surface area, therefore, creates more catalytic centers. The capability of rapid fabrication and N-doping as well as reduction of holey GO can lead to development of an efficient catalyst that can replace previous coin metals for energy generation and storage, such as fuel cells and metal-air batteries.

  18. Additional evidence for blepharismin photoreceptor pigment mediating step-up photophobic response of unicellular organism, Blepharisma.

    PubMed

    Matsuoka, T; Watanabe, Y; Sagara, Y; Takayanagi, M; Kato, Y

    1995-07-01

    In the ciliated protozoan, Blepharisma japonicum, the pink-colored pigment (blepharismin) contained in the pigment granules is believed to be the photoreceptor pigment responsible for the step-up photophobic response. When the cells partially bleached by extrusion of the pigment granules caused by cold shock were subsequently cultured under illuminated conditions, the pigment-less granules regenerated and the cells were further bleached (pigment content below 0.5%). The photosensitivity of such colorless cells disappeared completely. In contrast, the blepharismin pigment regenerated gradually when such colorless cells were transferred to darkness. The photosensitivity of the cells also recovered with regeneration of the pigment. We found that blepharismin pigment was not photobleached in the absence of O2. The step-up photophobic response was also completely repressed in the absence of O2. These results strongly confirm that blepharismin is a photoreceptor pigment mediating photobehavior of Blepharisma and that O2 is required for the early step in the phototransduction of the light-excited pigment.

  19. Characterization and analysis of surface notches on Ti-alloy plates fabricated by additive manufacturing techniques

    NASA Astrophysics Data System (ADS)

    Chan, Kwai S.

    2015-12-01

    Rectangular plates of Ti-6Al-4V with extra low interstitial (ELI) were fabricated by layer-by-layer deposition techniques that included electron beam melting (EBM) and laser beam melting (LBM). The surface conditions of these plates were characterized using x-ray micro-computed tomography. The depth and radius of surface notch-like features on the LBM and EBM plates were measured from sectional images of individual virtual slices of the rectangular plates. The stress concentration factors of individual surface notches were computed and analyzed statistically to determine the appropriate distributions for the notch depth, notch radius, and stress concentration factor. These results were correlated with the fatigue life of the Ti-6Al-4V ELI alloys from an earlier investigation. A surface notch analysis was performed to assess the debit in the fatigue strength due to the surface notches. The assessment revealed that the fatigue lives of the additively manufactured plates with rough surface topographies and notch-like features are dominated by the fatigue crack growth of large cracks for both the LBM and EBM materials. The fatigue strength reduction due to the surface notches can be as large as 60%-75%. It is concluded that for better fatigue performance, the surface notches on EBM and LBM materials need to be removed by machining and the surface roughness be improved to a surface finish of about 1 μm.

  20. Foreword: Additive Manufacturing: Interrelationships of Fabrication, Constitutive Relationships Targeting Performance, and Feedback to Process Control

    DOE PAGES

    Carpenter, John S.; Beese, Allison M.; Bourell, David L.; Hamilton, Reginald F.; Mishra, Rajiv; Sears, James

    2015-06-26

    Additive manufacturing (AM) offers distinct advantages over conventional manufacturing processes including the capability to both build and repair complex part shapes; to integrate and consolidate parts and thus overcome joining concerns; and to locally tailor material compositions as well as properties. Moreover, a variety of fields such as aerospace, military, automotive, and biomedical are employing this manufacturing technique as a way to decrease costs, increase manufacturing agility, and explore novel geometry/functionalities. In order to increase acceptance of AM as a viable processing method, pathways for qualifying both the material and the process need to be developed and, perhaps, standardized. Thismore » symposium was designed to serve as a venue for the international AM community—including government, academia, and industry—to define the fundamental interrelationships between feedstock, processing, microstructure, shape, mechanical behavior/materials properties, and function/performance. Eventually, insight into the connections between processing, microstructure, property, and performance will be achieved through experimental observations, theoretical advances, and computational modeling of physical processes. Finally, once this insight matures, AM will be able to move from the realm of making parts to making qualified materials that are certified for use with minimal need for post-fabrication characterization.« less

  1. Foreword: Additive Manufacturing: Interrelationships of Fabrication, Constitutive Relationships Targeting Performance, and Feedback to Process Control

    SciTech Connect

    Carpenter, John S.; Beese, Allison M.; Bourell, David L.; Hamilton, Reginald F.; Mishra, Rajiv; Sears, James

    2015-06-26

    Additive manufacturing (AM) offers distinct advantages over conventional manufacturing processes including the capability to both build and repair complex part shapes; to integrate and consolidate parts and thus overcome joining concerns; and to locally tailor material compositions as well as properties. Moreover, a variety of fields such as aerospace, military, automotive, and biomedical are employing this manufacturing technique as a way to decrease costs, increase manufacturing agility, and explore novel geometry/functionalities. In order to increase acceptance of AM as a viable processing method, pathways for qualifying both the material and the process need to be developed and, perhaps, standardized. This symposium was designed to serve as a venue for the international AM community—including government, academia, and industry—to define the fundamental interrelationships between feedstock, processing, microstructure, shape, mechanical behavior/materials properties, and function/performance. Eventually, insight into the connections between processing, microstructure, property, and performance will be achieved through experimental observations, theoretical advances, and computational modeling of physical processes. Finally, once this insight matures, AM will be able to move from the realm of making parts to making qualified materials that are certified for use with minimal need for post-fabrication characterization.

  2. One-step fabrication of nanostructured Ni film with lotus effect from deep eutectic solvent.

    PubMed

    Gu, Changdong; Tu, Jiangping

    2011-08-16

    We report a procedure to fabricate nanostructured Ni films via programmed electrochemical deposition from a choline-chloride-based ionic liquid at a high temperature of 90 °C. Three electrodeposition modes using constant voltage, pulse voltage, and reverse pulse voltage produce a variety of nanostructured Ni films with micro/nanobinary surface architectures, such as nanosheets, aligned nanostrips, and hierarchical flowers. The nanostructured Ni films possess face-centered cubic crystal structure. Amazingly, it is found that the electrodeposited Ni films deliver the superhydrophobic surfaces without any further modifications by low surface-energy materials, which might be attributed to the vigorous micro/nanobinary architectures and the surface chemical composition. The electrochemical measurements reveal that the superhydrophobic Ni film exhibit an obvious passivation phenomenon, which could provide enhanced corrosion resistance for the substrate in the aqueous solutions. PMID:21739965

  3. Preliminary Investigation of Keyhole Phenomena during Single Layer Fabrication in Laser Additive Manufacturing of Stainless Steel

    NASA Astrophysics Data System (ADS)

    Matilainen, Ville-Pekka; Piili, Heidi; Salminen, Antti; Nyrhilä, Olli

    Laser additive manufacturing (LAM) is a fabrication technology that enables production of complex parts from metallic materials with mechanical properties comparable to conventionally manufactured parts. In the LAM process, parts are manufactured by melting metallic powder layer-by-layer with a laser beam. This manufacturing technology is nowadays called powder bed fusion (PBF) according to the ASTM F2792-12a standard. This strategy involves several different independent and dependent thermal cycles, all of which have an influence on the final properties of the manufactured part. The quality of PBF parts depends strongly on the characteristics of each single laser-melted track and each single layer. This study consequently concentrates on investigating the effects of process parameters such as laser power on single track and layer formation and laser-material interaction phenomena occurring during the PBF process. Experimental tests were done with two different machines: a modified research machine based on an EOS EOSINT M-series system and an EOS EOSINT M280 system. The material used was EOS stainless steel 17-4 PH. Process monitoring was done with an active illuminated high speed camera system. After microscopy analysis, it was concluded that a keyhole can form during laser additive manufacturing of stainless steel. It was noted that heat input has an important effect on the likelihood of keyhole formation. The threshold intensity value for keyhole formation of 106 W/cm2 was exceeded in all manufactured single tracks. Laser interaction time was found to have an effect on penetration depth and keyhole formation, since the penetration depth increased with increased laser interaction time. It was also concluded that active illuminated high speed camera systems are suitable for monitoring of the manufacturing process and facilitate process control.

  4. Corrosion resistance properties of superhydrophobic copper surfaces fabricated by one-step electrochemical modification process

    NASA Astrophysics Data System (ADS)

    Huang, Ying; Sarkar, D. K.; Gallant, Danick; Chen, X.-Grant

    2013-10-01

    Superhydrophobic copper surfaces have been prepared by a one-step electrochemical modification process in an ethanolic stearic acid solution. In this work, the corrosion properties of hydrophobic copper surface and superhydrophobic copper surfaces were analyzed by means of electrochemical analyses and compared with that of as-received bare copper substrate. The decrease of corrosion current density (icorr) as well as the increase of polarization resistance (Rp) obtained from potentiodynamic polarization curves revealed that the superhydrophobic film on the copper surfaces improved the corrosion resistance performance of the copper substrate.

  5. Additive Manufacturing, Design, Testing, and Fabrication: A Full Engineering Experience at JSC

    NASA Technical Reports Server (NTRS)

    Zusack, Steven

    2016-01-01

    I worked on several projects this term. While most projects involved additive manufacturing, I was also involved with two design projects, two testing projects, and a fabrication project. The primary mentor for these was Richard Hagen. Secondary mentors were Hai Nguyen, Khadijah Shariff, and fabrication training from James Brown. Overall, my experience at JSC has been successful and what I have learned will continue to help me in my engineering education and profession long after I leave. My 3D printing projects ranged from less than a 1 cubic centimeter to about 1 cubic foot and involved several printers using different printing technologies. It was exciting to become familiar with printing technologies such as industrial grade FDM (Fused Deposition Modeling), the relatively new SLA (Stereolithography), and PolyJet. My primary duty with the FDM printers was to model parts that came in from various sources to print effectively and efficiently. Using methods my mentor taught me and the Stratasys Insight software, I was able to minimize imperfections, hasten build time, improve strength for specific forces (tensile, shear, etc...), and reduce likelihood of a print-failure. Also using FDM, I learned how to repair a part after it was printed. This is done by using a special kind of glue that chemically melts the two faces of plastic parts together to form a fused interface. My first goal with SLA technology was to bring the printer back to operational readiness. In becoming familiar with the Pegasus SLA printer, I researched the leveling, laser settings, and different vats to hold liquid material. With this research, I was successfully able to bring the Pegasus back online and have successfully printed multiple sample parts as well as functional parts. My experience with PolyJet technology has been focused on an understanding of the abilities/limits, costs, and the maintenance for daily use. Still upcoming will be experience with using a composite printer that uses FDM

  6. Growth of carbon nanowalls at atmospheric pressure for one-step gas sensor fabrication

    NASA Astrophysics Data System (ADS)

    Yu, Kehan; Bo, Zheng; Lu, Ganhua; Mao, Shun; Cui, Shumao; Zhu, Yanwu; Chen, Xinqi; Ruoff, Rodney S.; Chen, Junhong

    2011-12-01

    Carbon nanowalls (CNWs), two-dimensional "graphitic" platelets that are typically oriented vertically on a substrate, can exhibit similar properties as graphene. Growth of CNWs reported to date was exclusively carried out at a low pressure. Here, we report on the synthesis of CNWs at atmosphere pressure using "direct current plasma-enhanced chemical vapor deposition" by taking advantage of the high electric field generated in a pin-plate dc glow discharge. CNWs were grown on silicon, stainless steel, and copper substrates without deliberate introduction of catalysts. The as-grown CNW material was mainly mono- and few-layer graphene having patches of O-containing functional groups. However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing. A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth. The sensor responded to relatively low concentrations of NO2 (g) and NH3 (g), thus suggesting high-quality CNWs that are useful for room temperature gas sensors. PACS: Graphene (81.05.ue), Chemical vapor deposition (81.15.Gh), Gas sensors (07.07.Df), Atmospheric pressure (92.60.hv)

  7. Two step novel hydrogen system using additives to enhance hydrogen release from the hydrolysis of alane and activated aluminum

    SciTech Connect

    Zidan, Ragaiy; Teprovich, Joseph A.; Motyka, Theodore

    2015-12-01

    A system for the generation of hydrogen for use in portable power systems is set forth utilizing a two-step process that involves the thermal decomposition of AlH.sub.3 (10 wt % H.sub.2) followed by the hydrolysis of the activated aluminum (Al*) byproduct to release additional H.sub.2. Additionally, a process in which water is added directly without prior history to the AlH.sub.3:PA composite is also disclosed.

  8. Magnetic properties of planar nanowire arrays of Co fabricated on oxidized step-bunched silicon templates.

    PubMed

    Arora, S K; O'Dowd, B J; Ballesteros, B; Gambardella, P; Shvets, I V

    2012-06-15

    Planar nanowire (NW) arrays of Co grown on oxidized step-bunched Si(111) templates exhibit room temperature ferromagnetic behaviour for wire widths down to 25 nm. Temperature and thickness dependent magnetization studies on these polycrystalline NW arrays show that the magnetic anisotropy of the NW array is dominated by shape anisotropy, which keeps the magnetization in-plane with easy axis parallel to the wires. This shape related uniaxial anisotropy is preserved even at low temperatures (10 K). Thickness dependent studies reveal that the magnetization reversal is governed by the curling mode reversal for thick wires whereas thinner wires exhibit a more complex behaviour which is related to thermal effects and size distribution of the crystal grains that constitute the NWs.

  9. Migration of additive molecules in a polymer filament obtained by melt spinning: Influence of the fiber processing steps

    NASA Astrophysics Data System (ADS)

    Gesta, E.; Skovmand, O.; Espuche, E.; Fulchiron, R.

    2015-12-01

    The purpose of this study is to understand the influence of the yarn processing on the migration of additives molecules, especially insecticide, within polyethylene (PE) yarns. Yarns were manufactured in the laboratory focusing on three key-steps (spinning, post-stretching and heat-setting). Influence of each step on yarn properties was investigated using tensile tests, differential scanning calorimetry and wide-angle X-ray diffraction. The post-stretching step was proved to be critical in defining yarn mechanical and structural properties. Although a first orientation of polyethylene crystals was induced during spinning, the optimal orientation was only reached by post-stretching. The results also showed that the heat-setting did not significantly change these properties. The presence of additives crystals at the yarn surface was evidenced by scanning-electron microscopy. These studies performed at each yarn production step allowed a detailed analysis of the additives' ability to migrate. It is concluded that while post-stretching decreased the migration rate, heat-setting seems to boost this migration.

  10. One-step fabrication of three-dimensional polydimethylsiloxane peel-off microwell array for cell trapping

    NASA Astrophysics Data System (ADS)

    Xue, Ning; Bleris, Leonidas; Lee, Jeong-Bong (JB)

    2015-01-01

    A three-dimensional polydimethylsiloxane (PDMS)-based microarray was one-step fabricated by releasing from an SU-8 mold for cell trapping. A human embryonic kidney-293 cell line was cultured on the PDMS microarray. By taking advantage of the chemical nature difference between PDMS surface released from oxidized silicon and released from SU-8 substrate, cells can only grow and be attached inside the PDMS microarray after 2 days of cell culture. To investigate the substantial nature of the cell adhesion and repellency on the PDMS substrate, atomic force microscopy, contact angle, and x-ray photoelectron spectroscopy methods have been carried out to analyze the physical and chemical properties of the PDMS material surfaces under different surface treatment circumstances.

  11. One-step fabrication of inorganic/organic hybrid microspheres with tunable surface texture for controlled drug release application.

    PubMed

    Dong, Hua; Tang, Guannan; Ma, Ting; Cao, Xiaodong

    2016-01-01

    In this paper, we report one-step fabrication of poly(lactide-co-glycolic acid)/titanium oxide (PLGA/TiO2) hybrid microspheres with tunable surface texture via droplet-based microfluidics. Surface texture of microspheres can be continuously tuned by changing the mass ratio between titanium tetraisopropoxide (TTIP) and PLGA in the dispersed phase. The fast hydrolysis of TTIP on the droplet surface can generate a thin shell membrane, resulting in a wrinkled surface after extraction of organic solvent. In vitro drug release monitoring of tanshinone IIA-loaded PLGA/TiO2 hybrid microsphere reveals that surface texture can affect the drug release rate to a large extent without sacrificing the drug encapsulation efficiency. Our finding might benefit the sustained drug delivery where variable drug release rate and high drug encapsulation efficiency are both required. PMID:26610930

  12. Fabrication of non-flaking, superhydrophobic surfaces using a one-step solution-immersion process on copper foams

    NASA Astrophysics Data System (ADS)

    Xu, Jia; Xu, Jinliang; Cao, Yang; Ji, Xianbing; Yan, Yuying

    2013-12-01

    Non-flaking superhydrophobic surfaces were prepared using a simple one-step solution-immersion process on commercially obtained copper foam substrates. Copper foams were immersed in a 0.05 M ethanolic stearic acid solution at room temperature for several days. This formed coverage of copper stearate with micro- and nano-scale hierarchical surface morphology. The surface of the copper foam after 4 days of immersion demonstrates superhydrophobicity with a water contact angle of 156°. A sliding angel of 4° for a 5 μL droplet indicates excellent non-sticking behavior. Compared with a flat copper plate, the superhydrophobic surfaces based on copper foams are much more robust and mechanically stable. This work provides a promising strategy for scalable fabrication of superhydrophobic surfaces on 3D porous structures.

  13. One-step fabrication of membraneless microbial fuel cell cathode by electropolymerization of polypyrrole onto stainless steel mesh.

    PubMed

    Feng, Chunhua; Wan, Qunyi; Lv, Zhisheng; Yue, Xianjun; Chen, Yanfeng; Wei, Chaohai

    2011-05-15

    A unique one-step method for fabrication of a membraneless microbial fuel cell (MFC) cathode was developed by coating a conductive polymer onto stainless steel mesh. The resulting polypyrrole/anthraquinone-2-sulfonate (PPy/AQS) film was synthesized via electropolymerization using AQS as the dopants. The scanning electron microscopy results indicated that the PPy/AQS film was uniformly formed on the metal mesh electrode without cracks on its surface and featuring a globular structure. Being equipped with such a cathode that was able to catalyze oxygen reduction and prevent water leakage, the membraneless MFC allowed power generation over 250 h and exhibited a maximum power density of 575 mW m(-2). Increasing film thickness seemed to result in a reduction in power performance due to the increased ohmic resistance of the cathode material and the enhanced difficulty for oxygen diffusion inside the cathode.

  14. Multilayered film microreactors fabricated by a one-step thermal bonding technique with high reproducibility and their applications.

    PubMed

    Min, Kyoung-Ik; Kim, Jin-Oh; Kim, Heejin; Im, Do Jin; Kim, Dong-Pyo

    2016-03-21

    We report the versatile uses of multilayered polyimide (PI) film microreactors with various functions including pressure tolerance, three-dimensional mixing and multistep membrane emulsification. Such PI film microreactors were fabricated by a simple one-step thermal bonding technique with high reproducibility. Upon bonding at 300 °C for 1 hour, the thin and flexible film microdevices could withstand pressure up to 8.6 MPa and 16.3 MPa with PI adhesive film or fluoropolymer adhesive, respectively, due to differences in wettability. The hydrophilic and hydrophobic microchannel devices were used to generate monodisperse oil-in-water (O/W) and water-in-oil (W/O) droplets, and polymer micro/nanoparticles at a high generation frequency. A monolithic and chemical resistant film microreactor with a three-dimensional serpentine microchannel was used for the selective reduction of ester to aldehyde by efficient mixing and quenching in a flash chemistry manner, within a several 10(1) millisecond time scale. Furthermore, a novel multilayered film microreactor for organic-aqueous biphasic interfacial reactions was devised by embedding a membrane layer to induce chaotic mixing in both the interface and emulsified phase by flowing through multiple numbers of meshed structures along the hydrophobic channel. This simple and economic fabrication technique significantly facilitates mass production of multilayered film devices that could be useful as a platform for various microfluidic applications in chemistry and biology.

  15. Rapid Stencil Mask Fabrication Enabled One-Step Polymer-Free Graphene Patterning and Direct Transfer for Flexible Graphene Devices.

    PubMed

    Yong, Keong; Ashraf, Ali; Kang, Pilgyu; Nam, SungWoo

    2016-01-01

    We report a one-step polymer-free approach to patterning graphene using a stencil mask and oxygen plasma reactive-ion etching, with a subsequent polymer-free direct transfer for flexible graphene devices. Our stencil mask is fabricated via a subtractive, laser cutting manufacturing technique, followed by lamination of stencil mask onto graphene grown on Cu foil for patterning. Subsequently, micro-sized graphene features of various shapes are patterned via reactive-ion etching. The integrity of our graphene after patterning is confirmed by Raman spectroscopy. We further demonstrate the rapid prototyping capability of a stretchable, crumpled graphene strain sensor and patterned graphene condensation channels for potential applications in sensing and heat transfer, respectively. We further demonstrate that the polymer-free approach for both patterning and transfer to flexible substrates allows the realization of cleaner graphene features as confirmed by water contact angle measurements. We believe that our new method promotes rapid, facile fabrication of cleaner graphene devices, and can be extended to other two dimensional materials in the future. PMID:27118249

  16. Fabrication of Cu2ZnSnS4 Thin Film Solar Cell Using Single Step Electrodeposition Method

    NASA Astrophysics Data System (ADS)

    Pawar, Sambhaji M.; Pawar, Bharati S.; Gurav, Kishor V.; Bae, Do Won; Kwon, Se Han; Kolekar, Sanjay S.; Hyeok Kim, Jin

    2012-10-01

    Cu2ZnSnS4 (CZTS) thin films were deposited onto Mo-coated and tin-doped indium oxide (ITO) coated glass substrates by using single step electrodeposition technique followed by annealing in N2 + H2S atmosphere. Subsequently, they were applied to the fabrication of thin film solar cells. Upon annealing, the amorphous nature of as-deposited precursor film changes into polycrystalline kesterite crystal structure with uniform and densely packed surface morphology. Energy dispersive X-ray spectroscopy (EDS) study reveals that the deposited thin films are nearly stoichiometric. Optical absorption study shows the band gap energy of as-deposited CZTS thin films is 2.7 eV whereas, after annealing, it is found to be 1.53 eV. The solar cell fabricated with CZTS absorber layer, showed the best conversion efficiency (η) 1.21% for 0.44 cm2 with open-circuit voltage (Voc) = 315 mV, short-circuit current density (Jsc) = 12.27 mA/cm2 and fill factor (FF) = 0.31.

  17. Rapid Stencil Mask Fabrication Enabled One-Step Polymer-Free Graphene Patterning and Direct Transfer for Flexible Graphene Devices

    PubMed Central

    Yong, Keong; Ashraf, Ali; Kang, Pilgyu; Nam, SungWoo

    2016-01-01

    We report a one-step polymer-free approach to patterning graphene using a stencil mask and oxygen plasma reactive-ion etching, with a subsequent polymer-free direct transfer for flexible graphene devices. Our stencil mask is fabricated via a subtractive, laser cutting manufacturing technique, followed by lamination of stencil mask onto graphene grown on Cu foil for patterning. Subsequently, micro-sized graphene features of various shapes are patterned via reactive-ion etching. The integrity of our graphene after patterning is confirmed by Raman spectroscopy. We further demonstrate the rapid prototyping capability of a stretchable, crumpled graphene strain sensor and patterned graphene condensation channels for potential applications in sensing and heat transfer, respectively. We further demonstrate that the polymer-free approach for both patterning and transfer to flexible substrates allows the realization of cleaner graphene features as confirmed by water contact angle measurements. We believe that our new method promotes rapid, facile fabrication of cleaner graphene devices, and can be extended to other two dimensional materials in the future. PMID:27118249

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Rapid Stencil Mask Fabrication Enabled One-Step Polymer-Free Graphene Patterning and Direct Transfer for Flexible Graphene Devices

    NASA Astrophysics Data System (ADS)

    Yong, Keong; Ashraf, Ali; Kang, Pilgyu; Nam, Sungwoo

    2016-04-01

    We report a one-step polymer-free approach to patterning graphene using a stencil mask and oxygen plasma reactive-ion etching, with a subsequent polymer-free direct transfer for flexible graphene devices. Our stencil mask is fabricated via a subtractive, laser cutting manufacturing technique, followed by lamination of stencil mask onto graphene grown on Cu foil for patterning. Subsequently, micro-sized graphene features of various shapes are patterned via reactive-ion etching. The integrity of our graphene after patterning is confirmed by Raman spectroscopy. We further demonstrate the rapid prototyping capability of a stretchable, crumpled graphene strain sensor and patterned graphene condensation channels for potential applications in sensing and heat transfer, respectively. We further demonstrate that the polymer-free approach for both patterning and transfer to flexible substrates allows the realization of cleaner graphene features as confirmed by water contact angle measurements. We believe that our new method promotes rapid, facile fabrication of cleaner graphene devices, and can be extended to other two dimensional materials in the future.

  20. Migration of additive molecules in a polymer filament obtained by melt spinning: Influence of the fiber processing steps

    SciTech Connect

    Gesta, E.; Skovmand, O.; Espuche, E. Fulchiron, R.

    2015-12-17

    The purpose of this study is to understand the influence of the yarn processing on the migration of additives molecules, especially insecticide, within polyethylene (PE) yarns. Yarns were manufactured in the laboratory focusing on three key-steps (spinning, post-stretching and heat-setting). Influence of each step on yarn properties was investigated using tensile tests, differential scanning calorimetry and wide-angle X-ray diffraction. The post-stretching step was proved to be critical in defining yarn mechanical and structural properties. Although a first orientation of polyethylene crystals was induced during spinning, the optimal orientation was only reached by post-stretching. The results also showed that the heat-setting did not significantly change these properties. The presence of additives crystals at the yarn surface was evidenced by scanning-electron microscopy. These studies performed at each yarn production step allowed a detailed analysis of the additives’ ability to migrate. It is concluded that while post-stretching decreased the migration rate, heat-setting seems to boost this migration.

  1. Fabrication of extremely thermal-stable GaN template on Mo substrate using double bonding and step annealing process

    NASA Astrophysics Data System (ADS)

    Qing, Wang; Yang, Liu; Yongjian, Sun; Yuzhen, Tong; Guoyi, Zhang

    2016-08-01

    A new layer transfer technique which comprised double bonding and a step annealing process was utilized to transfer the GaN epilayer from a sapphire substrate to a Mo substrate. Combined with the application of the thermal-stable bonding medium, the resulting two-inch-diameter GaN template showed extremely good stability under high temperature and low stress state. Moreover, no cracks and winkles were observed. The transferred GaN template was suitable for homogeneous epitaxial, thus could be used for the direct fabrication of vertical LED chips as well as power electron devices. It has been confirmed that the double bonding and step annealing technique together with the thermal-stable bonding layer could significantly improve the bonding strength and stress relief, finally enhancing the thermal stability of the transferred GaN template. Project supported by the Guangdong Innovative Research Team Program (No. 2009010044), the China Postdoctoral Science Foundation (No. 2014M562233), the National Natural Science Foundation of Guangdong, China (No. 2015A030312011), and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics (No. IOSKL2014KF17).

  2. Fabrication and characterization of metal-packaged fiber Bragg grating sensor by one-step ultrasonic welding

    NASA Astrophysics Data System (ADS)

    Zhang, Yumin; Zhu, Lianqing; Luo, Fei; Dong, Mingli; Ding, Xiangdong; He, Wei

    2016-06-01

    A metallic packaging technique of fiber Bragg grating (FBG) sensors is developed for measurement of strain and temperature, and it can be simply achieved via one-step ultrasonic welding. The average strain transfer rate of the metal-packaged sensor is theoretically evaluated by a proposed model aiming at surface-bonded metallic packaging FBG. According to analytical results, the metallic packaging shows higher average strain transfer rate compared with traditional adhesive packaging under the same packaging conditions. Strain tests are performed on an elaborate uniform strength beam for both tensile and compressive strains; strain sensitivities of approximately 1.16 and 1.30 pm/μɛ are obtained for the tensile and compressive situations, respectively. Temperature rising and cooling tests are also executed from 50°C to 200°C, and the sensitivity of temperature is 36.59 pm/°C. All the measurements of strain and temperature exhibit good linearity and stability. These results demonstrate that the metal-packaged sensors can be successfully fabricated by one-step welding technique and provide great promise for long-term and high-precision structural health monitoring.

  3. Fabrication of Fe-FeAl Functionally Graded Material Using the Wire-Arc Additive Manufacturing Process

    NASA Astrophysics Data System (ADS)

    Shen, Chen; Pan, Zengxi; Cuiuri, Dominic; Roberts, Jon; Li, Huijun

    2016-02-01

    A functionally gradient iron-aluminum wall structure with aluminum composition gradient from 0 at. pct to over 50 at. pct is fabricated using a wire-arc additive manufacturing (WAAM) system. The as-fabricated alloy is investigated using optical microstructure analysis, hardness testing, tensile testing, X-ray diffraction phase characterization, and electron-dispersive spectrometry. The comprehensive analysis of the experimental samples has shown that the WAAM system can be used for manufacturing iron aluminide functionally graded material with full density, desired composition, and reasonable mechanical properties.

  4. Fabrication

    NASA Astrophysics Data System (ADS)

    Angel, Roger; Helms, Richard; Bilbro, Jim; Brown, Norman; Eng, Sverre; Hinman, Steve; Hull-Allen, Greg; Jacobs, Stephen; Keim, Robert; Ulmer, Melville

    1992-08-01

    What aspects of optical fabrication technology need to be developed so as to facilitate existing planned missions, or enable new ones? Throughout the submillimeter to UV wavelengths, the common goal is to push technology to the limits to make the largest possible apertures that are diffraction limited. At any one wavelength, the accuracy of the surface must be better than lambda/30 (rms error). The wavelength range is huge, covering four orders of magnitude from 1 mm to 100 nm. At the longer wavelengths, diffraction limited surfaces can be shaped with relatively crude techniques. The challenge in their fabrication is to make as large as possible a reflector, given the weight and volume constraints of the launch vehicle. The limited cargo diameter of the shuttle has led in the past to emphasis on deployable or erectable concepts such as the Large Deployable Reflector (LDR), which was studied by NASA for a submillimeter astrophysics mission. Replication techniques that can be used to produce light, low-cost reflecting panels are of great interest for this class of mission. At shorter wavelengths, in the optical and ultraviolet, optical fabrication will tax to the limit the most refined polishing methods. Methods of mechanical and thermal stabilization of the substrate will be severely stressed. In the thermal infrared, the need for large aperture is tempered by the even stronger need to control the telescope's thermal emission by cooled or cryogenic operation. Thus, the SIRTF mirror at 1 meter is not large and does not require unusually high accuracy, but the fabrication process must produce a mirror that is the right shape at a temperature of 4 K. Future large cooled mirrors will present more severe problems, especially if they must also be accurate enough to work at optical wavelengths. At the very shortest wavelengths accessible to reflecting optics, in the x-ray domain, the very low count fluxes of high energy photons place a premium on the collecting area. It is

  5. Fabrication

    NASA Technical Reports Server (NTRS)

    Angel, Roger; Helms, Richard; Bilbro, Jim; Brown, Norman; Eng, Sverre; Hinman, Steve; Hull-Allen, Greg; Jacobs, Stephen; Keim, Robert; Ulmer, Melville

    1992-01-01

    What aspects of optical fabrication technology need to be developed so as to facilitate existing planned missions, or enable new ones? Throughout the submillimeter to UV wavelengths, the common goal is to push technology to the limits to make the largest possible apertures that are diffraction limited. At any one wavelength, the accuracy of the surface must be better than lambda/30 (rms error). The wavelength range is huge, covering four orders of magnitude from 1 mm to 100 nm. At the longer wavelengths, diffraction limited surfaces can be shaped with relatively crude techniques. The challenge in their fabrication is to make as large as possible a reflector, given the weight and volume constraints of the launch vehicle. The limited cargo diameter of the shuttle has led in the past to emphasis on deployable or erectable concepts such as the Large Deployable Reflector (LDR), which was studied by NASA for a submillimeter astrophysics mission. Replication techniques that can be used to produce light, low-cost reflecting panels are of great interest for this class of mission. At shorter wavelengths, in the optical and ultraviolet, optical fabrication will tax to the limit the most refined polishing methods. Methods of mechanical and thermal stabilization of the substrate will be severely stressed. In the thermal infrared, the need for large aperture is tempered by the even stronger need to control the telescope's thermal emission by cooled or cryogenic operation. Thus, the SIRTF mirror at 1 meter is not large and does not require unusually high accuracy, but the fabrication process must produce a mirror that is the right shape at a temperature of 4 K. Future large cooled mirrors will present more severe problems, especially if they must also be accurate enough to work at optical wavelengths. At the very shortest wavelengths accessible to reflecting optics, in the x-ray domain, the very low count fluxes of high energy photons place a premium on the collecting area. It is

  6. Carboxylic Acids as A Traceless Activation Group for Conjugate Additions: A Three-Step Synthesis of (±)-Pregabalin

    PubMed Central

    2015-01-01

    The direct application of carboxylic acids as a traceless activation group for radical Michael additions has been accomplished via visible light-mediated photoredox catalysis. Photon-induced oxidation of a broad series of carboxylic acids, including hydrocarbon-substituted, α-oxy, and α-amino acids, provides a versatile CO2-extrusion platform to generate Michael donors without the requirement for organometallic activation or propagation. A diverse array of Michael acceptors is amenable to this new conjugate addition strategy. An application of this technology to a three-step synthesis of the medicinal agent pregabalin (commercialized by Pfizer under the trade name Lyrica) is also presented. PMID:25032785

  7. Holographic binary grating liquid crystal cells fabricated by one-step exposure of photocrosslinkable polymer liquid crystalline alignment substrates to a polarization interference ultraviolet beam.

    PubMed

    Kawai, Kotaro; Sasaki, Tomoyuki; Noda, Kohei; Sakamoto, Moritsugu; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2015-07-01

    Holographic binary grating liquid crystal (LC) cells, in which the optical anisotropy was rectangularly modulated even as the grating was fabricated using holographic exposure, were fabricated by one-step polarization holographic exposure of an empty glass cell, the interior of which was coated with a photocrosslinkable polymer LC (PCLC). The present study is of great significance in that three types of holographic binary grating LC cells containing twisted alignments can be fabricated by simultaneous exposure of two PCLC substrates to the UV interference beams, which are sinusoidally modulated. The polarization conversion properties of the diffracted beams are explained well by theoretical analysis based on Jones calculus. PMID:26193145

  8. Fabrication of p-type porous silicon nanowire with oxidized silicon substrate through one-step MACE

    SciTech Connect

    Li, Shaoyuan; Ma, Wenhui; Zhou, Yang; Chen, Xiuhua; Xiao, Yongyin; Ma, Mingyu; Wei, Feng; Yang, Xi

    2014-05-01

    In this paper, the simple pre-oxidization process is firstly used to treat the starting silicon wafer, and then MPSiNWs are successfully fabricated from the moderately doped wafer by one-step MACE technology in HF/AgNO{sub 3} system. The PL spectrum of MPSiNWs obtained from the oxidized silicon wafers show a large blue-shift, which can be attributed to the deep Q. C. effect induced by numerous mesoporous structures. The effects of HF and AgNO{sub 3} concentration on formation of SiNWs were carefully investigated. The results indicate that the higher HF concentration is favorable to the growth of SiNWs, and the density of SiNWs is significantly reduced when Ag{sup +} ions concentrations are too high. The deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon surface were studied. According to the experimental results, a model was proposed to explain the formation mechanism of porous SiNWs by etching the oxidized starting silicon. - Graphical abstract: Schematic cross-sectional views of PSiNWs array formation by etching oxidized silicon wafer in HF/AgNO{sub 3} solution. (A) At the starting point; (B) during the etching process; and (C) after Ag dendrites remove. - Highlights: • Prior to etching, a simple pre-oxidation is firstly used to treat silicon substrate. • The medially doped p-type MPSiNWs are prepared by one-step MACE. • Deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon are studied. • A model is finally proposed to explain the formation mechanism of PSiNWs.

  9. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  10. Microfluidic assisted one-step fabrication of porous silicon@acetalated dextran nanocomposites for precisely controlled combination chemotherapy.

    PubMed

    Liu, Dongfei; Zhang, Hongbo; Mäkilä, Ermei; Fan, Jin; Herranz-Blanco, Bárbara; Wang, Chang-Fang; Rosa, Ricardo; Ribeiro, António J; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2015-01-01

    An advanced nanocomposite consisting of an encapsulated porous silicon (PSi) nanoparticle and an acid-degradable acetalated dextran (AcDX) matrix (nano-in-nano), was efficiently fabricated by a one-step microfluidic self-assembly approach. The obtained nano-in-nano PSi@AcDX composites showed improved surface smoothness, homogeneous size distribution, and considerably enhanced cytocompatibility. Furthermore, multiple drugs with different physicochemical properties have been simultaneously loaded into the nanocomposites with a ratiometric control. The release kinetics of all the payloads was predominantly controlled by the decomposition rate of the outer AcDX matrix. To facilitate the intracellular drug delivery, a nona-arginine cell-penetrating peptide (CPP) was chemically conjugated onto the surface of the nanocomposites by oxime click chemistry. Taking advantage of the significantly improved cell uptake, the proliferation of two breast cancer cell lines was markedly inhibited by the CPP-functionalized multidrug-loaded nanocomposites. Overall, this nano-in-nano PSi@polymer composite prepared by the microfluidic self-assembly approach is a universal platform for nanoparticles encapsulation and precisely controlled combination chemotherapy. PMID:25468375

  11. Simple and Green Fabrication of a Superhydrophobic Surface by One-Step Immersion for Continuous Oil/Water Separation.

    PubMed

    Zhu, Jingfang; Liu, Bin; Li, Longyang; Zeng, Zhixiang; Zhao, Wenjie; Wang, Gang; Guan, Xiaoyan

    2016-07-21

    In this paper, stainless steel meshes with superhydrophobic and superoleophilic surfaces were fabricated by rapid and simple one-step immersion in a solution containing hydrochloric acid and stearic acid. The apparent contact angles were tested by a video contact angle measurement system (CA). Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were conducted to characterize the surface topographies and chemical compositions. The SEM results showed that mesh surfaces were covered by ferric stearate (Fe[CH3(CH2)16COO]2) with low surface energy. The CA test results showed that the mesh had a maximum apparent contact angle of 160 ± 1.0° and a sliding angle of less than 5.0° for the water droplet, whereas the apparent contact angle for the oil droplet was zero. Ultrasound oscillation and exposure tests at atmospheric conditions and immersion tests in 3.5 wt % NaCl aqueous solution were conducted to confirm the mesh with excellent superhydrophobic and superoleophilic properties. On the basis of the superhydrophobic mesh, a miniature separation device pump was designed to collect pure oil from the oil/water mixture. It showed that the device was easier and convenient. The techniques and materials presented in this work are promising for application to wastewater and oil spill treatment.

  12. Microfluidic assisted one-step fabrication of porous silicon@acetalated dextran nanocomposites for precisely controlled combination chemotherapy.

    PubMed

    Liu, Dongfei; Zhang, Hongbo; Mäkilä, Ermei; Fan, Jin; Herranz-Blanco, Bárbara; Wang, Chang-Fang; Rosa, Ricardo; Ribeiro, António J; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2015-01-01

    An advanced nanocomposite consisting of an encapsulated porous silicon (PSi) nanoparticle and an acid-degradable acetalated dextran (AcDX) matrix (nano-in-nano), was efficiently fabricated by a one-step microfluidic self-assembly approach. The obtained nano-in-nano PSi@AcDX composites showed improved surface smoothness, homogeneous size distribution, and considerably enhanced cytocompatibility. Furthermore, multiple drugs with different physicochemical properties have been simultaneously loaded into the nanocomposites with a ratiometric control. The release kinetics of all the payloads was predominantly controlled by the decomposition rate of the outer AcDX matrix. To facilitate the intracellular drug delivery, a nona-arginine cell-penetrating peptide (CPP) was chemically conjugated onto the surface of the nanocomposites by oxime click chemistry. Taking advantage of the significantly improved cell uptake, the proliferation of two breast cancer cell lines was markedly inhibited by the CPP-functionalized multidrug-loaded nanocomposites. Overall, this nano-in-nano PSi@polymer composite prepared by the microfluidic self-assembly approach is a universal platform for nanoparticles encapsulation and precisely controlled combination chemotherapy.

  13. Simple and Green Fabrication of a Superhydrophobic Surface by One-Step Immersion for Continuous Oil/Water Separation.

    PubMed

    Zhu, Jingfang; Liu, Bin; Li, Longyang; Zeng, Zhixiang; Zhao, Wenjie; Wang, Gang; Guan, Xiaoyan

    2016-07-21

    In this paper, stainless steel meshes with superhydrophobic and superoleophilic surfaces were fabricated by rapid and simple one-step immersion in a solution containing hydrochloric acid and stearic acid. The apparent contact angles were tested by a video contact angle measurement system (CA). Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were conducted to characterize the surface topographies and chemical compositions. The SEM results showed that mesh surfaces were covered by ferric stearate (Fe[CH3(CH2)16COO]2) with low surface energy. The CA test results showed that the mesh had a maximum apparent contact angle of 160 ± 1.0° and a sliding angle of less than 5.0° for the water droplet, whereas the apparent contact angle for the oil droplet was zero. Ultrasound oscillation and exposure tests at atmospheric conditions and immersion tests in 3.5 wt % NaCl aqueous solution were conducted to confirm the mesh with excellent superhydrophobic and superoleophilic properties. On the basis of the superhydrophobic mesh, a miniature separation device pump was designed to collect pure oil from the oil/water mixture. It showed that the device was easier and convenient. The techniques and materials presented in this work are promising for application to wastewater and oil spill treatment. PMID:27328269

  14. One-step modification of fabrics with bioinspired polydopamine@octadecylamine nanocapsules for robust and healable self-cleaning performance.

    PubMed

    Liu, Yanhua; Liu, Zhilu; Liu, Yupeng; Hu, Haiyuan; Li, Yi; Yan, Pengxun; Yu, Bo; Zhou, Feng

    2015-01-27

    An in-situ polymerization to coat fabrics with polydopamine-encapsulated octadecylamine endows the fabrics with self-cleaning and self-healing abilities. The treated fabric exhibits self-healing after losing its hydrophobicity. It is durable against washing and mechanical abrasion without changing the hydrophobicity. Thanks to the versatile adhesive property of polydopamine, the approach is compatibile with a variety of substrates, such as fabrics, glass, sponge, paper, and polymeric materials.

  15. Enhanced Self-Cleaning Properties on Polyester Fabric Under Visible Light Through Single-Step Synthesis of Cuprous Oxide Doped Nano-TiO2.

    PubMed

    Gaminian, Hamdam; Montazer, Majid

    2015-01-01

    Nowadays, introducing self-cleaning properties on various fabrics under daylight irradiation for automotive and upholstery application is in a central point of research. This can be achieved by application of metal-doped TiO2 nano particles on the textile fabrics. Here, alkali hydrolysis of polyester fabric has been carried out along with synthesis of Cu2 O/TiO2 nanoparticles in a single-step process by using sonochemical technique. CuSO4 .5H2 O was used as a source of copper in the presence of glucose as reducing and stabilizing agent. Moreover, central composite design based on response surface methodology (RSM) was used to determine the role of variables (CuSO4 .5H2 O, glucose and pH) and their effects on the self-cleaning properties and weight of the fabric. The self-cleaning property was investigated by degradation of Methylene blue on the surface of the treated fabrics under daylight. Further, the tensile properties, colorimetric measurement, and washing fastness of the treated fabric produced in the optimum conditions were investigated. The morphology of Cu2 O/TiO2 nanoparticles was examined using X-ray diffraction and field emission scanning electron microscopy (FESEM). The new polyester fabric obtained through in situ synthesis of Cu2 O/TiO2 nanoparticles can be used as a desirable stable fabric with high tensile strength and visible-light self-cleaning properties.

  16. Aerosol based direct-write micro-additive fabrication method for sub-mm 3D metal-dielectric structures

    NASA Astrophysics Data System (ADS)

    Rahman, Taibur; Renaud, Luke; Heo, Deuk; Renn, Michael; Panat, Rahul

    2015-10-01

    The fabrication of 3D metal-dielectric structures at sub-mm length scale is highly important in order to realize low-loss passives and GHz wavelength antennas with applications in wearable and Internet-of-Things (IoT) devices. The inherent 2D nature of lithographic processes severely limits the available manufacturing routes to fabricate 3D structures. Further, the lithographic processes are subtractive and require the use of environmentally harmful chemicals. In this letter, we demonstrate an additive manufacturing method to fabricate 3D metal-dielectric structures at sub-mm length scale. A UV curable dielectric is dispensed from an Aerosol Jet system at 10-100 µm length scale and instantaneously cured to build complex 3D shapes at a length scale  <1 mm. A metal nanoparticle ink is then dispensed over the 3D dielectric using a combination of jetting action and tilted dispense head, also using the Aerosol Jet technique and at a length scale 10-100 µm, followed by the nanoparticle sintering. Simulation studies are carried out to demonstrate the feasibility of using such structures as mm-wave antennas. The manufacturing method described in this letter opens up the possibility of fabricating an entirely new class of custom-shaped 3D structures at a sub-mm length scale with potential applications in 3D antennas and passives.

  17. Additive Manufacturing Modeling and Simulation A Literature Review for Electron Beam Free Form Fabrication

    NASA Technical Reports Server (NTRS)

    Seufzer, William J.

    2014-01-01

    Additive manufacturing is coming into industrial use and has several desirable attributes. Control of the deposition remains a complex challenge, and so this literature review was initiated to capture current modeling efforts in the field of additive manufacturing. This paper summarizes about 10 years of modeling and simulation related to both welding and additive manufacturing. The goals were to learn who is doing what in modeling and simulation, to summarize various approaches taken to create models, and to identify research gaps. Later sections in the report summarize implications for closed-loop-control of the process, implications for local research efforts, and implications for local modeling efforts.

  18. An Efficient Multi-Scale Simulation Architecture for the Prediction of Performance Metrics of Parts Fabricated Using Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Pal, Deepankar; Patil, Nachiket; Zeng, Kai; Teng, Chong; Stucker, Brent

    2015-09-01

    In this study, an overview of the computational tools developed in the area of metal-based additively manufactured (AM) to simulate the performance metrics along with their experimental validations will be presented. The performance metrics of the AM fabricated parts such as the inter- and intra-layer strengths could be characterized in terms of the melt pool dimensions, solidification times, cooling rates, granular microstructure, and phase morphologies along with defect distributions which are a function of the energy source, scan pattern(s), and the material(s). The four major areas of AM simulation included in this study are thermo-mechanical constitutive relationships during fabrication and in- service, the use of Euler angles for gaging static and dynamic strengths, the use of algorithms involving intelligent use of matrix algebra and homogenization extracting the spatiotemporal nature of these processes, a fast GPU architecture, and specific challenges targeted toward attaining a faster than real-time simulation efficiency and accuracy.

  19. Influence of NH4Cl Powder Addition for Fabrication of Aluminum Nitride Coating in Reactive Atmospheric Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

    2011-01-01

    Reactive plasma spray is the key to fabricating aluminum nitride (AlN) thermally sprayed coatings. It was possible to fabricate AlN/Al composite coatings using atmospheric plasma spray process through plasma nitriding of Al powders (Al 30 μm). The nitriding reaction and the AlN content could be improved by controlling the spray distance and the feedstock powder particle size. Increasing the spray distance and/or using smaller particle size of Al powders improved the in-flight nitriding reaction. However, it was difficult to fabricate thick and dense AlN coatings with an increase in the spray distance and/or when using fine particles. Thus, the coatings thickness was suppressed because of the complete nitriding of some particles (formation of AlN particles) during flight, which prevents the particle deposition. Furthermore, the excessive vaporization of Al fine particles (due to increased particle temperature) decreased the deposition efficiency. To fabricate thick AlN coatings in the reactive plasma spray process, improving the nitriding reaction of the large Al particles at short spray distance is required to decrease the vaporization of Al particles during flight. This study investigated the influence of adding ammonium chloride (NH4Cl) powders on the nitriding process of large Al powders and on the microstructure of the fabricated coatings. It was possible to fabricate thick AlN coatings at 100 mm spray distance with small addition of NH4Cl powders to the Al feedstock powders (30 μm). Addition of NH4Cl to the starting Al powders promoted the formation of AlN through changing the reaction path to vapor-phase nitridation chlorination-nitridation sequences as confirmed by the thermodynamic analysis of possible intermediate reactions. This changes the nitriding reaction to a mild way, so it is more controlled with no explosive mode and with relatively low heating rates. Thus, NH4Cl acts as a catalyst, nitrogen source, and diluent agent. Furthermore, the evolved

  20. One-step sonoelectrochemical fabrication of gold nanoparticle/carbon nanosheet hybrids for efficient surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Zhang, Kaige; Yao, Su; Li, Gongke; Hu, Yuling

    2015-01-01

    A simple, fast, reproducible and efficient one-step fabrication method was successfully developed to prepare gold nanoparticle/carbon nanosheet (Au NP/CNS) hybrids by using sonoelectrochemistry. This method involved simultaneous generation of carbon nanosheets (CNSs) by oxidation of a graphite anode and generation of Au NPs by reduction of AuCl4- on the surface of the cathode. Then the Au NPs modified with poly(diallyl dimethyl ammonium chloride) were self-assembled on the surface of the CNS. A homemade sonoelectrochemical device that provided both high-intensity electric and ultrasonic fields was applied. The ability to obtain Au NPs with a controlled size and distribution on the surface of the CNS benefitted from the synergistic effect of the electric field and ultrasonic field. The Au NPs on the CNS surface exhibited distinctive and high-quality SERS activity. The enhancement factor of the developed substrate was 1.2 × 106 using 4-aminothiophenol as the probe molecule. The Au NP/CNS hybrid showed a great increase of Raman signals for aromatic molecules because of the high affinity of the CNS for aromatic molecules and the SERS activity of Au NPs. This SERS substrate also showed charge selectivity for cationic aromatic dyes, due to the negative charge on the surface of the CNS. Subsequently, the potential practical application of the SERS substrate was evaluated by quantitative analysis of adenine. The results suggest that Au NP/CNS materials as sensitive SERS-active substrates have great potential for detection of biomolecules.A simple, fast, reproducible and efficient one-step fabrication method was successfully developed to prepare gold nanoparticle/carbon nanosheet (Au NP/CNS) hybrids by using sonoelectrochemistry. This method involved simultaneous generation of carbon nanosheets (CNSs) by oxidation of a graphite anode and generation of Au NPs by reduction of AuCl4- on the surface of the cathode. Then the Au NPs modified with poly(diallyl dimethyl ammonium

  1. Two step purification of Acinetobacter sp. lipase and its evaluation as a detergent additive at low temperatures.

    PubMed

    Saisubramanian, N; Sivasubramanian, S; Nandakumar, N; Indirakumar, B; Chaudhary, N Amaranath; Puvanakrishnan, R

    2008-08-01

    Acinetobacter sp. lipase was purified to homogeneity by a two-step process. The crude enzyme (along with biomass) was subjected to partial purification by aqueous two phase system (ATPS), avoiding centrifugation and filtration steps. Conditions for lipase partitioning by ATPS were optimized by response surface methodology (RSM) and a combination of 29.45% polyethylene glycol 8000, 15.5% phosphate, and a pH of 7.0 resulted in an optimal partition coefficient. Partially pure lipase was further purified by a modified batch process using Octyl Sepharose CL-4B in a vacuum filtration apparatus. This two-step process resulted in a purified lipase with a yield of 74.6% having a specific activity of 88.8 U/mg of protein and a purification fold of 14.92. The homogeneity of the lipase preparation obtained by the purification process was confirmed by reversed phase high performance liquid chromatography profile. The molecular weight of the purified lipase was found to be around 32 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified lipase exhibited pH and temperature optima of 8.5 and 37 degrees C, respectively. The lipase was active at low temperatures and it retained 86.8% activity at 10 degrees C. It also displayed other features such as stability over a broad range of pH (3.0-9.0) as well as stability in the presence of hydrogen peroxide and commercial detergents. Based on these characteristics, the potential of this lipase as an additive in laundry detergent formulation was evaluated under low temperature wash conditions. The results indicated that Acinetobacter sp. lipase increased the washing efficiency of the detergent Nirma by 21-24% at 15 degrees C-20 degrees C, respectively.

  2. Fabrication and characterization of Si3N4 ceramics without additives by high pressure hot pressing

    NASA Technical Reports Server (NTRS)

    Shimada, M.; Tanaka, A.; Yamada, T.; Koizumi, M.

    1984-01-01

    High pressure hot-pressing of Si3N4 without additives was performed using various kinds of Si3N4 powder as starting materials, and the relation between densification and alpha-beta phase transformation was studied. The temperature dependences of Vickers microhardness and fracture toughness were also examined. Densification of Si3N4 was divided into three stages, and it was found that densification and phase transformation of Si3N4 under pressure were closely associated. The results of the temperature dependence of Vickers microhardness indicated that the high-temperature hardness was strongly influenced not only by the density and microstructure of sintered body but also by the purity of starting powder. The fracture toughness values of Si3N4 bodies without additives were 3.29-4.39 MN/m to the 3/2 power and independent of temperature up to 1400 C.

  3. Fabrication of Thermoelectric Devices Using Additive-Subtractive Manufacturing Techniques: Application to Waste-Heat Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Tewolde, Mahder

    Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are well suited for waste-heat energy harvesting applications as opposed to primary energy generation. Commercially available thermoelectric modules are flat, inflexible and have limited sizes available. State-of-art manufacturing of TEG devices relies on assembling prefabricated parts with soldering, epoxy bonding, and mechanical clamping. Furthermore, efforts to incorporate them onto curved surfaces such as exhaust pipes, pump housings, steam lines, mixing containers, reaction chambers, etc. require custom-built heat exchangers. This is costly and labor-intensive, in addition to presenting challenges in terms of space, thermal coupling, added weight and long-term reliability. Additive manufacturing technologies are beginning to address many of these issues by reducing part count in complex designs and the elimination of sub-assembly requirements. This work investigates the feasibility of utilizing such novel manufacturing routes for improving the manufacturing process of thermoelectric devices. Much of the research in thermoelectricity is primarily focused on improving thermoelectric material properties by developing of novel materials or finding ways to improve existing ones. Secondary to material development is improving the manufacturing process of TEGs to provide significant cost benefits. To improve the device fabrication process, this work explores additive manufacturing technologies to provide an integrated and scalable approach for TE device manufacturing directly onto engineering component surfaces. Additive manufacturing techniques like thermal spray and ink-dispenser printing are developed with the aim of improving the manufacturing process of TEGs. Subtractive manufacturing techniques like laser micromachining are also studied in detail. This includes the laser processing parameters for cutting the thermal spray materials efficiently by

  4. Fabrication of Silica Glass from Rice Husk Ash with Spodumene Additions

    NASA Astrophysics Data System (ADS)

    Wasanapiarnpong, T.; Vorajesdarom, B.; Rujirakamort, E.; Nilpairach, S.; Mongkolkachit, C.

    2011-10-01

    Silica glass is an interesting material due to its low thermal expansion coefficient, high chemical inertness, and transparency. In this study, low cost rice husk ash waste containing mainly amorphous silica phase was used as a starting raw material. Formation of cristrobalite caused product damage during cooling down was suppressed by an addition of some sintering aids. Spodumene was selected to use as the sintering aid due to its ability to promote the sinterability of the rice husk ash by liquid phase forming. Lithium carbonate and aluminum nitrate were mixed with the rice husk ash as starting chemicals for spodumene forming. To investigate the effects of spodumene addition on densification, physical properties and thermal expansion coefficient, 25 and 50 mass% of spdumene were added to the mixture. Mixed powders were dry pressed into pellet shapes and sintered at 1000-1250 °C for 30 min in an electric furnace. It was found that 50 mass% addition of spodumene enhanced the densification of the specimens sintered at the temperature higher than 1250 °C. Water absorption was reduced to 1.11 % with bulk density of 2.12 g/cm3. Low thermal expansion coefficient of 2.70×10-6 /°C was achieved with only the petalite phase detection.

  5. One-Step Fabrication of Stretchable Copper Nanowire Conductors by a Fast Photonic Sintering Technique and Its Application in Wearable Devices.

    PubMed

    Ding, Su; Jiu, Jinting; Gao, Yue; Tian, Yanhong; Araki, Teppei; Sugahara, Tohru; Nagao, Shijo; Nogi, Masaya; Koga, Hirotaka; Suganuma, Katsuaki; Uchida, Hiroshi

    2016-03-01

    Copper nanowire (CuNW) conductors have been considered to have a promising perspective in the area of stretchable electronics due to the low price and high conductivity. However, the fabrication of CuNW conductors suffers from harsh conditions, such as high temperature, reducing atmosphere, and time-consuming transfer step. Here, a simple and rapid one-step photonic sintering technique was developed to fabricate stretchable CuNW conductors on polyurethane (PU) at room temperature in air environment. It was observed that CuNWs were instantaneously deoxidized, welded and simultaneously embedded into the soft surface of PU through the one-step photonic sintering technique, after which highly conductive network and strong adhesion between CuNWs and PU substrates were achieved. The CuNW/PU conductor with sheet resistance of 22.1 Ohm/sq and transmittance of 78% was achieved by the one-step photonic sintering technique within only 20 μs in air. Besides, the CuNW/PU conductor could remain a low sheet resistance even after 1000 cycles of stretching/releasing under 10% strain. Two flexible electronic devices, wearable sensor and glove-shaped heater, were fabricated using the stretchable CuNW/PU conductor, demonstrating that our CuNW/PU conductor could be integrated into various wearable electronic devices for applications in food, clothes, and medical supplies fields.

  6. Adding functionality with additive manufacturing: Fabrication of titanium-based antibiotic eluting implants.

    PubMed

    Cox, Sophie C; Jamshidi, Parastoo; Eisenstein, Neil M; Webber, Mark A; Hassanin, Hany; Attallah, Moataz M; Shepherd, Duncan E T; Addison, Owen; Grover, Liam M

    2016-07-01

    Additive manufacturing technologies have been utilised in healthcare to create patient-specific implants. This study demonstrates the potential to add new implant functionality by further exploiting the design flexibility of these technologies. Selective laser melting was used to manufacture titanium-based (Ti-6Al-4V) implants containing a reservoir. Pore channels, connecting the implant surface to the reservoir, were incorporated to facilitate antibiotic delivery. An injectable brushite, calcium phosphate cement, was formulated as a carrier vehicle for gentamicin. Incorporation of the antibiotic significantly (p=0.01) improved the compressive strength (5.8±0.7MPa) of the cement compared to non-antibiotic samples. The controlled release of gentamicin sulphate from the calcium phosphate cement injected into the implant reservoir was demonstrated in short term elution studies using ultraviolet-visible spectroscopy. Orientation of the implant pore channels were shown, using micro-computed tomography, to impact design reproducibility and the back-pressure generated during cement injection which ultimately altered porosity. The amount of antibiotic released from all implant designs over a 6hour period (<28% of the total amount) were found to exceed the minimum inhibitory concentrations of Staphylococcus aureus (16μg/mL) and Staphylococcus epidermidis (1μg/mL); two bacterial species commonly associated with periprosthetic infections. Antibacterial efficacy was confirmed against both bacterial cultures using an agar diffusion assay. Interestingly, pore channel orientation was shown to influence the directionality of inhibition zones. Promisingly, this work demonstrates the potential to additively manufacture a titanium-based antibiotic eluting implant, which is an attractive alternative to current treatment strategies of periprosthetic infections.

  7. Adding functionality with additive manufacturing: Fabrication of titanium-based antibiotic eluting implants.

    PubMed

    Cox, Sophie C; Jamshidi, Parastoo; Eisenstein, Neil M; Webber, Mark A; Hassanin, Hany; Attallah, Moataz M; Shepherd, Duncan E T; Addison, Owen; Grover, Liam M

    2016-07-01

    Additive manufacturing technologies have been utilised in healthcare to create patient-specific implants. This study demonstrates the potential to add new implant functionality by further exploiting the design flexibility of these technologies. Selective laser melting was used to manufacture titanium-based (Ti-6Al-4V) implants containing a reservoir. Pore channels, connecting the implant surface to the reservoir, were incorporated to facilitate antibiotic delivery. An injectable brushite, calcium phosphate cement, was formulated as a carrier vehicle for gentamicin. Incorporation of the antibiotic significantly (p=0.01) improved the compressive strength (5.8±0.7MPa) of the cement compared to non-antibiotic samples. The controlled release of gentamicin sulphate from the calcium phosphate cement injected into the implant reservoir was demonstrated in short term elution studies using ultraviolet-visible spectroscopy. Orientation of the implant pore channels were shown, using micro-computed tomography, to impact design reproducibility and the back-pressure generated during cement injection which ultimately altered porosity. The amount of antibiotic released from all implant designs over a 6hour period (<28% of the total amount) were found to exceed the minimum inhibitory concentrations of Staphylococcus aureus (16μg/mL) and Staphylococcus epidermidis (1μg/mL); two bacterial species commonly associated with periprosthetic infections. Antibacterial efficacy was confirmed against both bacterial cultures using an agar diffusion assay. Interestingly, pore channel orientation was shown to influence the directionality of inhibition zones. Promisingly, this work demonstrates the potential to additively manufacture a titanium-based antibiotic eluting implant, which is an attractive alternative to current treatment strategies of periprosthetic infections. PMID:27127071

  8. Pt metallization of laser transformed medical grade silicone rubber: Last step toward a miniaturized nerve electrode fabrication process

    NASA Astrophysics Data System (ADS)

    Dupas-Bruzek, C.; Dréan, P.; Derozier, D.

    2009-10-01

    Chronic nerve recording and stimulation became possible through the use of implanted electrodes cuffs. In particular, self-sizing spiral electrode cuffs limit mechanical damage to the tissue: these have been shown to be suitable for long term implantation in animal and in man. However, up to now, such electrode cuffs were handmade and were hardly reproducible. They possessed a small number of electrodes (dot contacts), each being linked to its own wire. In order to improve the selectivity of nerve recording and/or stimulation (functional electrical stimulation), the numbers of electrodes and tracks have to be increased within the same electrode cuff surface. To fulfill this requirement, we have developed a fabrication process that uses an UV laser to induce surface modification, which activates the silicone rubber and is used with a mask to give high definition tracks and electrodes. After this primary step, silicone rubber is immersed in a Pt autocatalytic bath leading to a selective Pt metallization of the laser activated tracks and electrodes. We report our process as well as the results on the Pt metallization, including its morphology, how the DC resistance of Pt tracks depends on the laser used and the irradiation conditions, and also the electrical resistance of Pt tracks submitted to Scotch tape tests or to imposed strains. We show that (i) the type of laser and the irradiation conditions have a strong influence on the nucleation and growth rate of platinum and thus on the DC resistance of the tracks, (ii) the tracks of width 400 μm and thickness 10 μm have a sheet resistivity of 0.2 Ω/sq, (iii) DC resistance does not change much during a 6 month soak in saline, (iv) strains above 2% breaks the track continuity, and (v) when strains below 53% are relaxed, the DC resistance returns to a low value. This recovery from large tensile strains means that nerve cuffs with such metallization could be handled by the surgeon without great care before and during

  9. Thermal Imaging for Assessment of Electron-Beam Free Form Fabrication (EBF(sup 3)) Additive Manufacturing Welds

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Burke, Eric R.; Hafley, Robert A.; Taminger, Karen M.; Domack, Christopher S.; Brewer, Amy R.; Martin, Richard E.

    2013-01-01

    Additive manufacturing is a rapidly growing field where 3-dimensional parts can be produced layer by layer. NASA s electron beam free-form fabrication (EBF(sup 3)) technology is being evaluated to manufacture metallic parts in a space environment. The benefits of EBF(sup 3) technology are weight savings to support space missions, rapid prototyping in a zero gravity environment, and improved vehicle readiness. The EBF(sup 3) system is composed of 3 main components: electron beam gun, multi-axis position system, and metallic wire feeder. The electron beam is used to melt the wire and the multi-axis positioning system is used to build the part layer by layer. To insure a quality weld, a near infrared (NIR) camera is used to image the melt pool and solidification areas. This paper describes the calibration and application of a NIR camera for temperature measurement. In addition, image processing techniques are presented for weld assessment metrics.

  10. Fabrication and thermal shock resistance of HfB2-SiC composite with B4C additives

    NASA Astrophysics Data System (ADS)

    Weng, L.; Han, W.; Hong, Ch.

    2011-12-01

    A HfB2 based ceramic matrix composite containing 20 vol.% SiC particles with 2 vol.% B4C as sintering additives was fabricated by hot-pressed sintering. The microstructure and properties, especially the thermal shock resistance of the composite were investigated. Results showed that the addition of B4C improved the powder sinterability and led to obtaining nearly full dense composite. The flexural strength and fracture toughness of the composite were 771 MPa and 7.06 MPam1/2, respectively. The thermal shock resistance tests indicated that the residual strength decreased significantly when the thermal shock temperature difference was higher than 600 °C. The large number of microcracks on the sample surface was the main reason for the catastrophic failure.

  11. Microstructural Characterization of Bonding Interfaces in Aluminum 3003 Blocks Fabricated by Ultrasonic Additive Manufacturing

    SciTech Connect

    Schick, D. E.; Babu, Sudarsanam Suresh; Lippold, John C; Hahnlen, R.M.; Dapino, M.J.; Dehoff, Ryan R; Collins, P.

    2010-01-01

    Ultrasonic additive manufacturing (UAM) is a process by which hybrid and near-netshaped products can be manufactured from thin metallic tapes. One of the main concerns of UAM is the development of anisotropic mechanical properties. In this work, the microstructures in the bond regions are characterized with optical and electron microscopy. Recrystallization and grain growth across the interface are proposed as a mechanism for the bond formation. The presence of voids or unbonded areas, which reduce the load-bearing cross section and create a stress intensity factor, is attributed to the transfer of the sonotrode texture to the new foil layer. This results in large peaks and valleys that are not filled in during processing. Tensile testing revealed the weld interface strength was 15% of the bulk foil. Shear tests of the weld interfaces showed almost 50% of the bulk shear strength of the material. Finally, optical microscopy of the fracture surfaces from the tensile tests revealed 34% of the interface area was unbonded.

  12. Preliminary Comparison of Properties between Ni-electroplated Stainless Steel Parts Fabricated with Laser Additive Manufacturing and Conventional Machining

    NASA Astrophysics Data System (ADS)

    Mäkinen, Mika; Jauhiainen, Eeva; Matilainen, Ville-Pekka; Riihimäki, Jaakko; Ritvanen, Jussi; Piili, Heidi; Salminen, Antti

    Laser additive manufacturing (LAM) is a fabrication technology, which enables production of complex parts from metallic materials with mechanical properties comparable to those of conventionally machined parts. These LAM parts are manufactured via melting metallic powder layer by layer with laser beam. Aim of this study is to define preliminarily the possibilities of using electroplating to supreme surface properties. Electrodeposited nickel and chromium as well as electroless (autocatalytic) deposited nickel was used to enhance laser additive manufactured and machined parts properties, like corrosion resistance, friction and wearing. All test pieces in this study were manufactured with a modified research AM equipment, equal to commercial EOS M series. The laser system used for tests was IPG 200 W CW fiber laser. The material used in this study for additive manufacturing was commercial stainless steel powder grade named SS316L. This SS316L is not equal to AISI 316L grade, but commercial name of this kind of powder is widely known in additive manufacturing as SS316L. Material used for fabrication of comparison test pieces (i.e. conventionally manufactured) was AISI 316L stainless steel bar. Electroplating was done in matrix cell and electroless was done in plastic sink properties of plated parts were tested within acetic acid salt spray corrosion chamber (AASS, SFS-EN-ISO 9227 standard). Adhesion of coating, friction and wearing properties were tested with Pin-On-Rod machine. Results show that in these preliminary tests, LAM parts and machined parts have certain differences due to manufacturing route and surface conditions. These have an effect on electroplated and electroless parts features on adhesion, corrosion, wearing and friction. However, further and more detailed studies are needed to fully understand these phenomena.

  13. Additive Fabrication of Conductive Patterns by a Template Transfer Process Based on Benzotriazole Adsorption As a Separation Layer.

    PubMed

    Chang, Yu; Yang, Zhen-Guo

    2016-06-01

    The traditional subtractive process to fabricate conductive patterns is environmentally harmful, wasteful, and limited in line width. The additive process, including direct printing of conductive paste or ink, direct printing of catalytic ink, laser-induced forward transfer, etc., can solve these problems. However, the current additive process also faces many difficulties such as low electrical and adhesion properties, low pattern thickness, high cost, etc. Benzotriazole (BTA), as widely used corrosion inhibitor, can be adsorbed onto a copper surface. The electroplated copper film on BTA-adsorbed copper foil shows poor adhesion. On the basis of this phenomenon, a novel template transfer process to additively fabricate conductive patterns has been developed. A permeant antiadhesive mask is printed on carrier copper foil, and then, BTA is adsorbed onto the exposed area of the carrier foil, thus forming the template. The template is electroplated to grow conductive patterns in the exposed parts, and then can be adhered to the flexible substrate. The substrate is peeled off, with the transfer of the conductive patterns to the substrate, to form the designed conductive patterns on PET. By reimmersing the template into BTA solution, the template can be used again. The mechanism of BTA adsorption and the reason for the low peeling strength are researched using Raman spectra, XPS and electrochemical impedance spectroscopy. Copper patterns more than 20 μm in thickness can be prepared on PET, the resistivity of the prepared copper patterns is 2.01 μΩ cm, which is about the same as bulk copper, and the peeling strength of the pattern on PET is measured to be 6.97 N/cm. This template transfer process, with no waste, low pollution, high electrical and adhesion properties, and low cost, shows high potential in the large scale manufacturing of electronic devices, such as RFID circuitry, FPCs, etc.

  14. Additive Fabrication of Conductive Patterns by a Template Transfer Process Based on Benzotriazole Adsorption As a Separation Layer.

    PubMed

    Chang, Yu; Yang, Zhen-Guo

    2016-06-01

    The traditional subtractive process to fabricate conductive patterns is environmentally harmful, wasteful, and limited in line width. The additive process, including direct printing of conductive paste or ink, direct printing of catalytic ink, laser-induced forward transfer, etc., can solve these problems. However, the current additive process also faces many difficulties such as low electrical and adhesion properties, low pattern thickness, high cost, etc. Benzotriazole (BTA), as widely used corrosion inhibitor, can be adsorbed onto a copper surface. The electroplated copper film on BTA-adsorbed copper foil shows poor adhesion. On the basis of this phenomenon, a novel template transfer process to additively fabricate conductive patterns has been developed. A permeant antiadhesive mask is printed on carrier copper foil, and then, BTA is adsorbed onto the exposed area of the carrier foil, thus forming the template. The template is electroplated to grow conductive patterns in the exposed parts, and then can be adhered to the flexible substrate. The substrate is peeled off, with the transfer of the conductive patterns to the substrate, to form the designed conductive patterns on PET. By reimmersing the template into BTA solution, the template can be used again. The mechanism of BTA adsorption and the reason for the low peeling strength are researched using Raman spectra, XPS and electrochemical impedance spectroscopy. Copper patterns more than 20 μm in thickness can be prepared on PET, the resistivity of the prepared copper patterns is 2.01 μΩ cm, which is about the same as bulk copper, and the peeling strength of the pattern on PET is measured to be 6.97 N/cm. This template transfer process, with no waste, low pollution, high electrical and adhesion properties, and low cost, shows high potential in the large scale manufacturing of electronic devices, such as RFID circuitry, FPCs, etc. PMID:27171553

  15. Oxygen and nitrogen plasma etching of three-dimensional hydroxyapatite/chitosan scaffolds fabricated by additive manufacturing

    NASA Astrophysics Data System (ADS)

    Myung, Sung-Woon; Kim, Byung-Hoon

    2016-01-01

    Three-dimensional (3D) chitosan and hydroxyapatite (HAp)/chitosan (CH) scaffolds were fabricated by additive manufacturing, then their surfaces were etched with oxygen (O2) and nitrogen (N2) plasma. O2 and N2 plasma etching was performed to increase surface properties such as hydrophilicity, roughness, and surface chemistry on the scaffolds. After etching, hydroxyapatite was exposed on the surface of 3D HAp/CH scaffolds. The surface morphology and chemical properties were characterized by contact angle measurement, scanning electron microscopy, X-ray diffraction, and attenuated total reflection Fourier infrared spectroscopy. The cell viability of 3D chitosan scaffolds was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The differentiation of preosteoblast cells was evaluated by alkaline phosphatase assay. The cell viability was improved by O2 and N2 plasma etching of 3D chitosan scaffolds. The present fabrication process for 3D scaffolds might be applied to a potential tool for preparing biocompatible scaffolds.

  16. Hydrogenation of O and OH on Pt(111): A comparison between the reaction rates of the first and the second hydrogen addition steps

    SciTech Connect

    Näslund, L.-Å.

    2014-03-14

    The formation of water through hydrogenation of oxygen on platinum occurs at a surprisingly low reaction rate. The reaction rate limited process for this catalytic reaction is, however, yet to be settled. In the present work, the reaction rates of the first and the second hydrogen addition steps are compared when hydrogen is obtained through intense synchrotron radiation that induces proton production in a water overlayer on top of the adsorbed oxygen species. A substantial amount of the produced hydrogen diffuses to the platinum surface and promotes water formation at the two starting conditions O/Pt(111) and (H{sub 2}O+OH)/Pt(111). The comparison shows no significant difference in the reaction rate between the first and the second hydrogen addition steps, which indicates that the rate determining process of the water formation from oxygen on Pt(111) is neither the first nor the second H addition step or, alternatively, that both H addition steps exert rate control.

  17. Alkali Metal Halide Salts as Interface Additives to Fabricate Hysteresis-Free Hybrid Perovskite-Based Photovoltaic Devices.

    PubMed

    Wang, Lili; Moghe, Dhanashree; Hafezian, Soroush; Chen, Pei; Young, Margaret; Elinski, Mark; Martinu, Ludvik; Kéna-Cohen, Stéphane; Lunt, Richard R

    2016-09-01

    A new method was developed for doping and fabricating hysteresis-free hybrid perovskite-based photovoltaic devices by using alkali metal halide salts as interface layer additives. Such salt layers introduced at the perovskite interface can provide excessive halide ions to fill vacancies formed during the deposition and annealing process. A range of solution-processed halide salts were investigated. The highest performance of methylammonium lead mixed-halide perovskite device was achieved with a NaI interlayer and showed a power conversion efficiency of 12.6% and a hysteresis of less than 2%. This represents a 90% improvement compared to control devices without this salt layer. Through depth-resolved mass spectrometry, optical modeling, and photoluminescence spectroscopy, this enhancement is attributed to the reduction of iodide vacancies, passivation of grain boundaries, and improved hole extraction. Our approach ultimately provides an alternative and facile route to high-performance and hysteresis-free perovskite solar cells. PMID:27532662

  18. Alkali Metal Halide Salts as Interface Additives to Fabricate Hysteresis-Free Hybrid Perovskite-Based Photovoltaic Devices.

    PubMed

    Wang, Lili; Moghe, Dhanashree; Hafezian, Soroush; Chen, Pei; Young, Margaret; Elinski, Mark; Martinu, Ludvik; Kéna-Cohen, Stéphane; Lunt, Richard R

    2016-09-01

    A new method was developed for doping and fabricating hysteresis-free hybrid perovskite-based photovoltaic devices by using alkali metal halide salts as interface layer additives. Such salt layers introduced at the perovskite interface can provide excessive halide ions to fill vacancies formed during the deposition and annealing process. A range of solution-processed halide salts were investigated. The highest performance of methylammonium lead mixed-halide perovskite device was achieved with a NaI interlayer and showed a power conversion efficiency of 12.6% and a hysteresis of less than 2%. This represents a 90% improvement compared to control devices without this salt layer. Through depth-resolved mass spectrometry, optical modeling, and photoluminescence spectroscopy, this enhancement is attributed to the reduction of iodide vacancies, passivation of grain boundaries, and improved hole extraction. Our approach ultimately provides an alternative and facile route to high-performance and hysteresis-free perovskite solar cells.

  19. Facile and controllable one-step fabrication of molecularly imprinted polymer membrane by magnetic field directed self-assembly for electrochemical sensing of glutathione.

    PubMed

    Zhu, Wanying; Jiang, Guoyi; Xu, Lei; Li, Bingzhi; Cai, Qizhi; Jiang, Huijun; Zhou, Xuemin

    2015-07-30

    Based on magnetic field directed self-assembly (MDSA) of the ternary Fe3O4@PANI/rGO nanocomposites, a facile and controllable molecularly imprinted electrochemical sensor (MIES) was fabricated through a one-step approach for detection of glutathione (GSH). The ternary Fe3O4@PANI/rGO nanocomposites were obtained by chemical oxidative polymerization and intercalation of Fe3O4@PANI into the graphene oxide layers via π-π stacking interaction, followed by reduction of graphene oxide in the presence of hydrazine hydrate. In molecular imprinting process, the pre-polymers, including GSH as template molecule, Fe3O4@PANI/rGO nanocomposites as functional monomers and pyrrole as both cross-linker and co-monomer, was assembled through N-H hydrogen bonds and the electrostatic interaction, and then was rapidly oriented onto the surface of MGCE under the magnetic field induction. Subsequently, the electrochemical GSH sensor was formed by electropolymerization. In this work, the ternary Fe3O4@PANI/rGO nanocomposites could not only provide available functionalized sites in the matrix to form hydrogen bond and electrostatic interaction with GSH, but also afford a promoting network for electron transfer. Moreover, the biomimetic sensing membrane could be controlled more conveniently and effectively by adjusting the magnetic field strength. The as-prepared controllable sensor showed good stability and reproducibility for the determination of GSH with the detection limit reaching 3 nmol L(-1) (S/N = 3). In addition, the highly sensitive and selective biomimetic sensor has been successfully used for the clinical determination of GSH in biological samples.

  20. One-step fabrication of a highly conductive and durable copper paste and its flexible dipole tag-antenna application.

    PubMed

    Shin, Keun-Young; Lee, James S; Hong, Jin-Yong; Jang, Jyongsik

    2014-03-21

    A highly conductive and durable copper (Cu) paste was successfully fabricated via acid treatment and mechanical blending with corrosion inhibitors. A screen-printed Cu pattern was evaluated as a dipole tag-antenna with long term and thermal stability, and structural flexibility. PMID:24514876

  1. Thermally stable multi-mode polymer optical waveguide fabricated by single-step photo-patterning of fluorinated polyimide/epoxy hybrids

    NASA Astrophysics Data System (ADS)

    Urano, Yuichi; Chen, Ningjuan; Nakano, Kaichiro; Maeda, Katsumi; Ando, Shinji

    2008-02-01

    Novel polyimide (PI)/epoxy hybrid material for single-step photo-patterning of optical waveguides was prepared by blending of a semi-aromatic fluorinated poly(amic acid silylester) (PASE), a cycloaliphatic epoxy compound, and a photo-acid generator. A large refractive index change (δn, > 0.01), which is sufficient for multi-mode optical waveguides, was obtained between the polymer films prepared with and without UV irradiation. The refractive index change was generated by cationic reaction between the silylated carbonyl ester groups of PASE and epoxy rings, which was initiated by UV irradiation and promoted by successive thermal curing. The difference in molecular structures, which results in the refractive index changes, were characterized by FT-IR measurements, and it was clarified that the films with and without UV irradiation showed PASE and PI structures, respectively. These films exhibited high thermal stability higher than 230°C, which are desirable for waveguide fabrication for optical inter-connects and lightwave circuits. Using this hybrid material, channel-type optical waveguides were successfully fabricated by the single-step photo-patterning procedure without development by aqueous or organic solvents, which is more facile and economical for waveguide mass-fabrication.

  2. Facile fabrication of a silicon nanowire sensor by two size reduction steps for detection of alpha-fetoprotein biomarker of liver cancer

    NASA Astrophysics Data System (ADS)

    Binh Pham, Van; ThanhTung Pham, Xuan; Nhat Khoa Phan, Thanh; Thanh Tuyen Le, Thi; Chien Dang, Mau

    2015-12-01

    We present a facile technique that only uses conventional micro-techniques and two size-reduction steps to fabricate wafer-scale silicon nanowire (SiNW) with widths of 200 nm. Initially, conventional lithography was used to pattern SiNW with 2 μm width. Then the nanowire width was decreased to 200 nm by two size-reduction steps with isotropic wet etching. The fabricated SiNW was further investigated when used with nanowire field-effect sensors. The electrical characteristics of the fabricated SiNW devices were characterized and pH sensitivity was investigated. Then a simple and effective surface modification process was carried out to modify SiNW for subsequent binding of a desired receptor. The complete SiNW-based biosensor was then used to detect alpha-fetoprotein (AFP), one of the medically approved biomarkers for liver cancer diagnosis. Electrical measurements showed that the developed SiNW biosensor could detect AFP with concentrations of about 100 ng mL-1. This concentration is lower than the necessary AFP concentration for liver cancer diagnosis.

  3. Enhancement of the photo conversion efficiencies in Cu(In,Ga)(Se,S){sub 2} solar cells fabricated by two-step sulfurization process

    SciTech Connect

    Yang, JungYup; Nam, Junggyu; Kim, Dongseop; Lee, Dongho E-mail: ddang@korea.ac.kr; Kim, GeeYeong; Jo, William; Kang, Yoonmook E-mail: ddang@korea.ac.kr

    2015-11-09

    Cu(In,Ga)(Se,S){sub 2} (CIGSS) absorber layers were fabricated by using a modified two-stage sputter and a sequential selenization/sulfurization method, and the sulfurization process is changed from one-step to two-step. The two-step sulfurization was controlled with two different H{sub 2}S gas concentrations during the sulfurization treatment. This two-step process yielded remarkable improvements in the efficiency (+0.7%), open circuit voltage (+14 mV), short circuit current (+0.23 mA/cm{sup 2}), and fill factor (+0.21%) of a CIGSS device with 30 × 30 cm{sup 2} in size, owing to the good passivation at the grain boundary surface, uniform material composition among the grain boundaries, and modified depth profile of Ga and S. The deterioration of the P/N junction quality was prevented by the optimized S content in the CIGSS absorber layer. The effects of the passivation quality at the grain boundary surface, the material uniformity, the compositional depth profiles, the microstructure, and the electrical characteristics were examined by Kelvin probe force microscopy, X-ray diffraction, secondary ion mass spectrometry, scanning electron microscopy, and current-voltage curves, respectively. The two-step sulfurization process is experimentally found to be useful for obtaining good surface conditions and, enhancing the efficiency, for the mass production of large CIGSS modules.

  4. Dual-Charged Hollow Fiber Membranes for Low-Pressure Nanofiltration Based on Polyelectrolyte Complexes: One-Step Fabrication with Tailored Functionalities.

    PubMed

    Gherasim, Cristina Veronica; Luelf, Tobias; Roth, Hannah; Wessling, Matthias

    2016-07-27

    A new nanofiltration (NF) hollow fiber membrane is developed by using two oppositely charged polyelectrolytes coagulating into a polyelectrolyte complex (PEC) onto polyether sulfone base polymer. The particular membrane architecture emerges during a single-step procedure, allowing setting both the porous negatively charged support of the hollow fiber and the separation layer containing also the positive polyelectrolyte (PEI/PDADMAC) through a single layer dry-jet wet spinning process. The novelty is two-pronged: the composition of the hollow fiber membrane itself and its fabrication procedure (one-step fabrication of membranes employing polyelectrolytes). These result in highly permeable hollow fiber membranes with a stable separation layer and performance at par with the membranes reported in literature obtained by multistep processes. More importantly, the membranes are obtained through a simple, very fast (one-step), and less expensive procedure. The best performance among these newly obtained hollow-fiber membranes is achieved by PD5% hollow fiber (MWCO of 300 Da), which showed 7.6 L/m(2)·h·bar permeability and ∼90% rejection of MgCl2, MgSO4, and Na2SO4 at 2 bar pressure. Thus, the resulting membranes not only have the advantages of the hollow-fiber configuration, but perform very well at extremely low pressures (the lowest reported in the literature). The broad impact of the results presented in this Article lies in the potential to dramatically reduce both the fabrication (duration and complexity) and the price and desalination costs of highly performing NF hollow fiber membranes. These might result in interesting potential applications and open new directions toward designing efficient functional NF hollow fibers for water desalination.

  5. Dual-Charged Hollow Fiber Membranes for Low-Pressure Nanofiltration Based on Polyelectrolyte Complexes: One-Step Fabrication with Tailored Functionalities.

    PubMed

    Gherasim, Cristina Veronica; Luelf, Tobias; Roth, Hannah; Wessling, Matthias

    2016-07-27

    A new nanofiltration (NF) hollow fiber membrane is developed by using two oppositely charged polyelectrolytes coagulating into a polyelectrolyte complex (PEC) onto polyether sulfone base polymer. The particular membrane architecture emerges during a single-step procedure, allowing setting both the porous negatively charged support of the hollow fiber and the separation layer containing also the positive polyelectrolyte (PEI/PDADMAC) through a single layer dry-jet wet spinning process. The novelty is two-pronged: the composition of the hollow fiber membrane itself and its fabrication procedure (one-step fabrication of membranes employing polyelectrolytes). These result in highly permeable hollow fiber membranes with a stable separation layer and performance at par with the membranes reported in literature obtained by multistep processes. More importantly, the membranes are obtained through a simple, very fast (one-step), and less expensive procedure. The best performance among these newly obtained hollow-fiber membranes is achieved by PD5% hollow fiber (MWCO of 300 Da), which showed 7.6 L/m(2)·h·bar permeability and ∼90% rejection of MgCl2, MgSO4, and Na2SO4 at 2 bar pressure. Thus, the resulting membranes not only have the advantages of the hollow-fiber configuration, but perform very well at extremely low pressures (the lowest reported in the literature). The broad impact of the results presented in this Article lies in the potential to dramatically reduce both the fabrication (duration and complexity) and the price and desalination costs of highly performing NF hollow fiber membranes. These might result in interesting potential applications and open new directions toward designing efficient functional NF hollow fibers for water desalination. PMID:27406046

  6. A novel, two-step top seeded infiltration and growth process for the fabrication of single grain, bulk (RE)BCO superconductors

    NASA Astrophysics Data System (ADS)

    Namburi, Devendra K.; Shi, Yunhua; Palmer, Kysen G.; Dennis, Anthony R.; Durrell, John H.; Cardwell, David A.

    2016-09-01

    A fundamental requirement of the fabrication of high performing, (RE)-Ba-Cu-O bulk superconductors is achieving a single grain microstructure that exhibits good flux pinning properties. The top seeded melt growth (TSMG) process is a well-established technique for the fabrication of single grain (RE)BCO bulk samples and is now applied routinely by a number of research groups around the world. The introduction of a buffer layer to the TSMG process has been demonstrated recently to improve significantly the general reliability of the process. However, a number of growth-related defects, such as porosity and the formation of micro-cracks, remain inherent to the TSMG process, and are proving difficult to eliminate by varying the melt process parameters. The seeded infiltration and growth (SIG) process has been shown to yield single grain samples that exhibit significantly improved microstructures compared to the TSMG technique. Unfortunately, however, SIG leads to other processing challenges, such as the reliability of fabrication, optimisation of RE2BaCuO5 (RE-211) inclusions (size and content) in the sample microstructure, practical oxygenation of as processed samples and, hence, optimisation of the superconducting properties of the bulk single grain. In the present paper, we report the development of a near-net shaping technique based on a novel two-step, buffer-aided top seeded infiltration and growth (BA-TSIG) process, which has been demonstrated to improve greatly the reliability of the single grain growth process and has been used to fabricate successfully bulk, single grain (RE)BCO superconductors with improved microstructures and superconducting properties. A trapped field of ˜0.84 T and a zero field current density of 60 kA cm-2 have been measured at 77 K in a bulk, YBCO single grain sample of diameter 25 mm processed by this two-step BA-TSIG technique. To the best of our knowledge, this value of trapped field is the highest value ever reported for a sample

  7. A novel, two-step top seeded infiltration and growth process for the fabrication of single grain, bulk (RE)BCO superconductors

    NASA Astrophysics Data System (ADS)

    Namburi, Devendra K.; Shi, Yunhua; Palmer, Kysen G.; Dennis, Anthony R.; Durrell, John H.; Cardwell, David A.

    2016-09-01

    A fundamental requirement of the fabrication of high performing, (RE)–Ba–Cu–O bulk superconductors is achieving a single grain microstructure that exhibits good flux pinning properties. The top seeded melt growth (TSMG) process is a well-established technique for the fabrication of single grain (RE)BCO bulk samples and is now applied routinely by a number of research groups around the world. The introduction of a buffer layer to the TSMG process has been demonstrated recently to improve significantly the general reliability of the process. However, a number of growth-related defects, such as porosity and the formation of micro-cracks, remain inherent to the TSMG process, and are proving difficult to eliminate by varying the melt process parameters. The seeded infiltration and growth (SIG) process has been shown to yield single grain samples that exhibit significantly improved microstructures compared to the TSMG technique. Unfortunately, however, SIG leads to other processing challenges, such as the reliability of fabrication, optimisation of RE2BaCuO5 (RE-211) inclusions (size and content) in the sample microstructure, practical oxygenation of as processed samples and, hence, optimisation of the superconducting properties of the bulk single grain. In the present paper, we report the development of a near-net shaping technique based on a novel two-step, buffer-aided top seeded infiltration and growth (BA-TSIG) process, which has been demonstrated to improve greatly the reliability of the single grain growth process and has been used to fabricate successfully bulk, single grain (RE)BCO superconductors with improved microstructures and superconducting properties. A trapped field of ∼0.84 T and a zero field current density of 60 kA cm‑2 have been measured at 77 K in a bulk, YBCO single grain sample of diameter 25 mm processed by this two-step BA-TSIG technique. To the best of our knowledge, this value of trapped field is the highest value ever reported for a

  8. Electron Beam Lithography Double Step Exposure Technique for Fabrication of Mushroom-Like Profile in Bilayer Resist System

    NASA Astrophysics Data System (ADS)

    Kornelia, Indykiewicz; Bogdan, Paszkiewicz; Tomasz, Szymański; Regina, Paszkiewicz

    2015-01-01

    The Hi/Lo bilayer resist system exposure in e-beam lithography (EBL) process, intended for mushroom-like profile fabrication, was studied. Different exposure parameters and theirs influence on the resist layers were simulated in CASINO software and the obtained results were compared with the experimental data. The AFM technique was used for the estimation of the e-beam penetration depth in the resist stack. Performed numerical and experimental results allow us to establish the useful ranges of the exposure parameters.

  9. Fabrication of Step-and-Flash Imprint Lithography (S-FIL) templates using XeF2 enhanced focused ion-beam etching

    NASA Astrophysics Data System (ADS)

    Kettle, J.; Hoyle, R. T.; Dimov, S.

    2009-09-01

    The fabrication of Step-and-Flash Imprint Lithography (S-FIL) templates with line widths of 50 nm is described in this work. The structures have been patterned using a Ga+ focused ion beam (FIB) in a quartz template. FIB milling is generally accompanied with re-deposition effects, which represent a hindrance to densely patterned nanostructures required in most NIL applications. To reduce these re-deposition effects, in this research, xenon difluoride (XeF2) enhanced FIB etching was applied that also increases the material removal rates in comparison to pure kinetic ion sputtering. To optimise the process when using XeF2 gas the following ion scanning parameters have been examined: ion dose, beam current, dwell time and beam overlap (step size). It has been found that the assisting gases at very low doses do not bring significant etching enhancements whilst the sputtering rates have increased at high doses. Using the XeF2 gas-assisted etching, FIB structuring has been used to fabricate <100 nm structures onto quartz S-FIL templates. The presence of XeF2 considerably enhances the etching rate of quartz without any significant negative effects on the spatial resolution of the FIB lithographic process and reduces the template processing time.

  10. Fabrication of a Microbial Biosensor Based on QD-MWNT Supports by a One-Step Radiation Reaction and Detection of Phenolic Compounds in Red Wines

    PubMed Central

    Kim, Seul-Ki; Kwen, Hai-Doo; Choi, Seong-Ho

    2011-01-01

    An Acaligense sp.-immobilized biosensor was fabricated based on QD-MWNT composites as an electron transfer mediator and a microbe immobilization support by a one-step radiation reaction and used for sensing phenolic compounds in commercial red wines. First, a quantum dot-modified multi-wall carbon nanotube (QD-MWNT) composite was prepared in the presence of MWNT by a one-step radiation reaction in an aqueous solution at room temperature. The successful preparation of the QD-MWNT composite was confirmed by XPS, TEM, and elemental analysis. Second, the microbial biosensor was fabricated by immobilization of Acaligense sp. on the surface of the composite thin film of a glassy carbon (GC) electrode, which was prepared by a hand casting method with a mixture of the previously obtained composite and Nafion solution. The sensing ranges of the microbial biosensor based on CdS-MWNT and Cu2S-MWNT supports were 0.5–5.0 mM and 0.7–10 mM for phenol in a phosphate buffer solution, respectively. Total concentration of phenolic compounds contained in commercial red wines was also determined using the prepared microbial immobilized biosensor. PMID:22319395

  11. A Four-Step and Four-Criteria Approach for Evaluating Evidence of Dose Addition in Chemical Mixture Toxicity

    EPA Science Inventory

    Dose addition is the most frequently-used component-based approach for predicting dose response for a mixture of toxicologically-similar chemicals and for statistical evaluation of whether the mixture response is consistent with dose additivity and therefore predictable from the ...

  12. Fabrication of homogenous multilayered W films by multi-step sputtering deposition: a novel grain boundary enrichment strategy.

    PubMed

    Zhu, Hailin; Yang, Jijun; Wan, Qiang; Lin, Liwei; Liao, Jiali; Yang, Yuanyou; Liu, Ning

    2015-11-01

    Using a multi-step deposition approach, we develop a strategy of homogeneous multilayered (HM) structure to enrich the grain boundary (GB) of sputtered W films. In comparison with the single-layered film, the HM W film is easily controllable for the film GB density. When decreasing the film modulation period t m from 160 nm to 7 nm, the GB density gradually increased from 0.065 nm(-1) to 0.275 nm(-1) without changing the phase structure of the films. Accordingly, the film's electrical resistivity and mechanical hardness, which are related to the GBs, changed from 40.1 μΩ · cm to 75.3 μΩ · cm and from 12.1 GPa to 16.2 GPa, respectively. Detailed analysis showed that the formation of an HM structure is related to the temperature evolution of the film growing surface during the multi-step sputtering process. This study could provide a general engineering approach to enrich film interfaces and allows for the development of thin films with novel microstructures.

  13. One-step spray-coating process for the fabrication of colorful superhydrophobic coatings with excellent corrosion resistance.

    PubMed

    Li, Jian; Wu, Runni; Jing, Zhijiao; Yan, Long; Zha, Fei; Lei, Ziqiang

    2015-10-01

    A simple method was used to generate colorful hydrophobic stearate particles via chemical reactions between inorganic salts and sodium stearate. Colored self-cleaning superhydrophobic coatings were prepared through a facile one-step spray-coating process by spraying the stearate particle suspensions onto stainless steel substrates. Furthermore, the colorful superhydrophobic coating maintains excellent chemical stability under both harsh acidic and alkaline circumstances. After being immersed in a 3.5 wt % NaCl aqueous solution for 1 month, the as-prepared coatings remained superhydrophobic; however, they lost their self-cleaning property with a sliding angle of about 46 ± 3°. The corrosion behavior of the superhydrophobic coatings on the Al substrate was characterized by the polarization curve and electrochemical impedance spectroscopy (EIS). The electrochemical corrosion test results indicated that the superhydrophobic coatings possessed excellent corrosion resistance, which could supply efficient and long-term preservation for the bare Al substrate.

  14. Effect of PEG additive on anode microstructure and cell performance of anode-supported MT-SOFCs fabricated by phase inversion method

    NASA Astrophysics Data System (ADS)

    Ren, Cong; Liu, Tong; Maturavongsadit, Panita; Luckanagul, Jittima Amie; Chen, Fanglin

    2015-04-01

    Anode-supported micro-tubular solid oxide fuel cells (MT-SOFCs) have been fabricated by phase inversion method. For the anode support preparation, N-methyl-2-pyrrolidone (NMP), polyethersulfone (PESf) and poly ethylene glycol (PEG) were applied as solvent, polymer binder and additive, respectively. The effect of molecular weight and amount of PEG additive on the thermodynamics of the casting solutions was characterized by measuring the coagulation value. Viscosity of the casting slurries was also measured and the influence of PEG additive on viscosity was studied and discussed. The presence of PEG in the casting slurry can significantly influence the final anode support microstructure. Based on the microstructure result and the measured gas permeation value, two anode supports were selected for cell fabrication. For cell with the anode support fabricated using slurry with PEG additive, a maximum cell power density of 704 mW cm-2 is obtained at 750 °C with humidified hydrogen as fuel and ambient air as oxidant; cell fabricated without any PEG additive shows the peak cell power density of 331 mW cm-2. The relationship between anode microstructure and cell performance was discussed.

  15. Treatment planning of adhesive additive rehabilitations: the progressive wax-up of the three-step technique.

    PubMed

    Vailati, Francesca; Carciofo, Sylvain

    2016-01-01

    A full-mouth rehabilitation should be correctly planned from the start by using a diagnostic wax-up to reduce the potential for remakes, increased chair time, and laboratory costs. However, determining the clinical validity of an extensive wax-up can be complicated for clinicians who lack the experience of full-mouth rehabilitations. The three-step technique is a simplified approach that has been developed to facilitate the clinician's task. By following this technique, the diagnostic wax-up is progressively developed to the final outcome through the interaction between patient, clinician, and laboratory technician. This article provides guidelines aimed at helping clinicians and laboratory technicians to become more proactive in the treatment planning of full-mouth rehabilitations, by starting from the three major parameters of incisal edge position, occlusal plane position, and the vertical dimension of occlusion.

  16. Treatment planning of adhesive additive rehabilitations: the progressive wax-up of the three-step technique.

    PubMed

    Vailati, Francesca; Carciofo, Sylvain

    2016-01-01

    A full-mouth rehabilitation should be correctly planned from the start by using a diagnostic wax-up to reduce the potential for remakes, increased chair time, and laboratory costs. However, determining the clinical validity of an extensive wax-up can be complicated for clinicians who lack the experience of full-mouth rehabilitations. The three-step technique is a simplified approach that has been developed to facilitate the clinician's task. By following this technique, the diagnostic wax-up is progressively developed to the final outcome through the interaction between patient, clinician, and laboratory technician. This article provides guidelines aimed at helping clinicians and laboratory technicians to become more proactive in the treatment planning of full-mouth rehabilitations, by starting from the three major parameters of incisal edge position, occlusal plane position, and the vertical dimension of occlusion. PMID:27433550

  17. Fabrication of rectorite-contained nanoparticles for drug delivery with a green and one-step synthesis method.

    PubMed

    Tu, Hu; Lu, Yuan; Wu, Yang; Tian, Jing; Zhan, Yingfei; Zeng, Zhaoyang; Deng, Hongbing; Jiang, Linbin

    2015-09-30

    The composite nanoparticles (NPs) consisted of quaternized chitosan (QC)/bovine serum albumin (BSA)/rectorite (REC) were prepared successfully just by adding BSA solution into QC-REC nanocomposites solution via electrostatic interactions. The average diameter of NPs increased with the accretion of REC, which was demonstrated with dynamic laser scattering (DLS) and transmission electron microscopy (TEM). The results of small angle X-ray diffraction (SAXRD) and selected area electron diffraction (SAED) demonstrated that the intercalated structure of REC was enlarged with the addition of REC. Besides, it can was proved that the interaction had occurred between QC and REC in NPs with fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). In addition, doxorubicin (DOX) was used to investigate the entrapment efficiency and release pattern in NPs. It turned out to be that the addition of REC could increase the encapsulation efficiency (EE) and loading capacity (LC). The results also exhibited that the drug release in simulated gastric fluid reduced apparently with the addition of REC, which could ensure more DOX released in intestines. PMID:26231105

  18. Tubing-Electrospinning: A One-Step Process for Fabricating Fibrous Matrices with Spatial, Chemical, and Mechanical Gradients.

    PubMed

    Kim, Jung-Suk; Im, Byung Gee; Jin, Gyuhyung; Jang, Jae-Hyung

    2016-08-31

    Guiding newly generated tissues in a gradient pattern, thereby precisely mimicking inherent tissue morphology and subsequently arranging the intimate networks between adjacent tissues, is essential to raise the technical levels of tissue engineering and facilitate its transition into the clinic. In this study, a straightforward electrospinning method (the tubing-electrospinning technique) was developed to create fibrous matrices readily with diverse gradient patterns and to induce patterned cellular responses. Gradient fibrous matrices can be produced simply by installing a series of polymer-containing lengths of tubing into an electrospinning circuit and sequentially processing polymers without a time lag. The loading of polymer samples with different characteristics, including concentration, wettability, and mechanical properties, into the tubing system enabled unique features in fibrous matrices, such as longitudinal gradients in fiber density, surface properties, and mechanical stiffness. The resulting fibrous gradients were shown to arrange cellular migration and residence in a gradient manner, thereby offering efficient cues to mediate patterned tissue formation. The one-step process using tubing-electrospinning apparatus can be used without significant modifications regardless of the type of fibrous gradient. Hence, the tubing-electrospinning system can serve as a platform that can be readily used by a wide-range of users to induce patterned tissue formation in a gradient manner, which will ultimately improve the functionality of tissue engineering scaffolds.

  19. Design of underwater superoleophobic TiO{sub 2} coatings with additional photo-induced self-cleaning properties by one-step route bio-inspired from fish scales

    SciTech Connect

    Wang, Hao; Guo, Zhiguang

    2014-05-05

    Self-cleaning properties inspired by the structures and functions of some creatures are of great interest since the late 20th century. In this paper, TiO{sub 2} coatings with hierarchical rutile TiO{sub 2} flowers on fluorine-doped tin oxide substrate are fabricated through a simple one-step hydrothermal method. The flower-like coatings exhibit superhydrophilicity in air and superoleophobicity underwater with a contact angle as high as 157°, presenting good underwater self-cleaning performance. In addition, when contaminated by oleic acid, the as-prepared TiO{sub 2} coatings also exhibit excellent photocatalytic capability under ultraviolet irradiation, which demonstrated self-cleaning properties in a different way. This self-cleaning film provides a good strategy for some industrial and ocean applications.

  20. Three-dimensional Aerographite-GaN hybrid networks: Single step fabrication of porous and mechanically flexible materials for multifunctional applications

    NASA Astrophysics Data System (ADS)

    Schuchardt, Arnim; Braniste, Tudor; Mishra, Yogendra K.; Deng, Mao; Mecklenburg, Matthias; Stevens-Kalceff, Marion A.; Raevschi, Simion; Schulte, Karl; Kienle, Lorenz; Adelung, Rainer; Tiginyanu, Ion

    2015-03-01

    Three dimensional (3D) elastic hybrid networks built from interconnected nano- and microstructure building units, in the form of semiconducting-carbonaceous materials, are potential candidates for advanced technological applications. However, fabrication of these 3D hybrid networks by simple and versatile methods is a challenging task due to the involvement of complex and multiple synthesis processes. In this paper, we demonstrate the growth of Aerographite-GaN 3D hybrid networks using ultralight and extremely porous carbon based Aerographite material as templates by a single step hydride vapor phase epitaxy process. The GaN nano- and microstructures grow on the surface of Aerographite tubes and follow the network architecture of the Aerographite template without agglomeration. The synthesized 3D networks are integrated with the properties from both, i.e., nanoscale GaN structures and Aerographite in the form of flexible and semiconducting composites which could be exploited as next generation materials for electronic, photonic, and sensors applications.

  1. Photoelectrochemical, impedance and optical data for self Sn-diffusion doped Fe2O3 photoanodes fabricated at high temperature by one and two-step annealing methods

    PubMed Central

    Shinde, Pravin S.; Annamalai, Alagappan; Kim, Ju Hun; Choi, Sun Hee; Lee, Jae Sung; Jang, Jum Suk

    2015-01-01

    The optical, morphological and photoelectrochemical (PEC) properties of transition metal oxide semiconductors are important to understand their influence on water oxidation performance. Herein, we provide experimental evidences for a better understanding of the factors that dictate the interactions of Sn-diffusion doping on the PEC properties of Fe2O3 photoanodes fabricated at high temperature by one- and two-step annealing methods. The synthesis, characterization methods and other experimental details are provided. Limited previous information on the PEC and electrochemical impedance spectroscopic studies has been published. This data article contains Supplementary data, figures and methods related to the research article by Shinde et al. (2015) [1]. Here, we provide a further set of the obtained experimental data results. PMID:26693514

  2. Three-dimensional Aerographite-GaN hybrid networks: single step fabrication of porous and mechanically flexible materials for multifunctional applications.

    PubMed

    Schuchardt, Arnim; Braniste, Tudor; Mishra, Yogendra K; Deng, Mao; Mecklenburg, Matthias; Stevens-Kalceff, Marion A; Raevschi, Simion; Schulte, Karl; Kienle, Lorenz; Adelung, Rainer; Tiginyanu, Ion

    2015-03-06

    Three dimensional (3D) elastic hybrid networks built from interconnected nano- and microstructure building units, in the form of semiconducting-carbonaceous materials, are potential candidates for advanced technological applications. However, fabrication of these 3D hybrid networks by simple and versatile methods is a challenging task due to the involvement of complex and multiple synthesis processes. In this paper, we demonstrate the growth of Aerographite-GaN 3D hybrid networks using ultralight and extremely porous carbon based Aerographite material as templates by a single step hydride vapor phase epitaxy process. The GaN nano- and microstructures grow on the surface of Aerographite tubes and follow the network architecture of the Aerographite template without agglomeration. The synthesized 3D networks are integrated with the properties from both, i.e., nanoscale GaN structures and Aerographite in the form of flexible and semiconducting composites which could be exploited as next generation materials for electronic, photonic, and sensors applications.

  3. Two-step fabrication of self-catalyzed Ga-based semiconductor nanowires on Si by molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Yu, Xuezhe; Li, Lixia; Wang, Hailong; Xiao, Jiaxing; Shen, Chao; Pan, Dong; Zhao, Jianhua

    2016-05-01

    For the epitaxial growth of Ga-based III-V semiconductor nanowires (NWs) on Si, Ga droplets could provide a clean and compatible solution in contrast to the common Au catalyst. However, the use of Ga droplets is rather limited except for that in Ga-catalyzed GaAs NW studies in a relatively narrow growth temperature (Ts) window around 620 °C on Si. In this paper, we have investigated the two-step growth of Ga-catalyzed III-V NWs on Si (111) substrates by molecular-beam epitaxy. First, by optimizing the surface oxide, vertically aligned GaAs NWs with a high yield are obtained at Ts = 620 °C. Then a two-temperature procedure is adopted to preserve Ga droplets at lower Ts, which leads to an extension of Ts down to 500 °C for GaAs NWs. Based on this procedure, systematic morphological and structural studies for Ga-catalyzed GaAs NWs in the largest Ts range could be presented. Then within the same growth scheme, for the first time, we demonstrate Ga-catalyzed GaAs/GaSb heterostructure NWs. These GaSb NWs are axially grown on the GaAs NW sections and are pure zinc-blende single crystals. Compositional measurements confirm that the catalyst particles indeed mainly consist of Ga and GaSb sections are of high purity but with a minor composition of As. In the end, we present GaAsSb NW growth with a tunable Sb composition. Our results provide useful information for the controllable synthesis of multi-compositional Ga-catalyzed III-V semiconductor NWs on Si for heterogeneous integration.For the epitaxial growth of Ga-based III-V semiconductor nanowires (NWs) on Si, Ga droplets could provide a clean and compatible solution in contrast to the common Au catalyst. However, the use of Ga droplets is rather limited except for that in Ga-catalyzed GaAs NW studies in a relatively narrow growth temperature (Ts) window around 620 °C on Si. In this paper, we have investigated the two-step growth of Ga-catalyzed III-V NWs on Si (111) substrates by molecular-beam epitaxy. First, by

  4. Two-step fabrication of self-catalyzed Ga-based semiconductor nanowires on Si by molecular-beam epitaxy.

    PubMed

    Yu, Xuezhe; Li, Lixia; Wang, Hailong; Xiao, Jiaxing; Shen, Chao; Pan, Dong; Zhao, Jianhua

    2016-05-19

    For the epitaxial growth of Ga-based III-V semiconductor nanowires (NWs) on Si, Ga droplets could provide a clean and compatible solution in contrast to the common Au catalyst. However, the use of Ga droplets is rather limited except for that in Ga-catalyzed GaAs NW studies in a relatively narrow growth temperature (Ts) window around 620 °C on Si. In this paper, we have investigated the two-step growth of Ga-catalyzed III-V NWs on Si (111) substrates by molecular-beam epitaxy. First, by optimizing the surface oxide, vertically aligned GaAs NWs with a high yield are obtained at Ts = 620 °C. Then a two-temperature procedure is adopted to preserve Ga droplets at lower Ts, which leads to an extension of Ts down to 500 °C for GaAs NWs. Based on this procedure, systematic morphological and structural studies for Ga-catalyzed GaAs NWs in the largest Ts range could be presented. Then within the same growth scheme, for the first time, we demonstrate Ga-catalyzed GaAs/GaSb heterostructure NWs. These GaSb NWs are axially grown on the GaAs NW sections and are pure zinc-blende single crystals. Compositional measurements confirm that the catalyst particles indeed mainly consist of Ga and GaSb sections are of high purity but with a minor composition of As. In the end, we present GaAsSb NW growth with a tunable Sb composition. Our results provide useful information for the controllable synthesis of multi-compositional Ga-catalyzed III-V semiconductor NWs on Si for heterogeneous integration.

  5. A high-yield two-step transfer printing method for large-scale fabrication of organic single-crystal devices on arbitrary substrates.

    PubMed

    Deng, Wei; Zhang, Xiujuan; Pan, Huanhuan; Shang, Qixun; Wang, Jincheng; Zhang, Xiaohong; Zhang, Xiwei; Jie, Jiansheng

    2014-01-01

    Single-crystal organic nanostructures show promising applications in flexible and stretchable electronics, while their applications are impeded by the large incompatibility with the well-developed photolithography techniques. Here we report a novel two-step transfer printing (TTP) method for the construction of organic nanowires (NWs) based devices onto arbitrary substrates. Copper phthalocyanine (CuPc) NWs are first transfer-printed from the growth substrate to the desired receiver substrate by contact-printing (CP) method, and then electrode arrays are transfer-printed onto the resulting receiver substrate by etching-assisted transfer printing (ETP) method. By utilizing a thin copper (Cu) layer as sacrificial layer, microelectrodes fabricated on it via photolithography could be readily transferred to diverse conventional or non-conventional substrates that are not easily accessible before with a high transfer yield of near 100%. The ETP method also exhibits an extremely high flexibility; various electrodes such as Au, Ti, and Al etc. can be transferred, and almost all types of organic devices, such as resistors, Schottky diodes, and field-effect transistors (FETs), can be constructed on planar or complex curvilinear substrates. Significantly, these devices can function properly and exhibit closed or even superior performance than the device counterparts fabricated by conventional approach. PMID:24942458

  6. A High-yield Two-step Transfer Printing Method for Large-scale Fabrication of Organic Single-crystal Devices on Arbitrary Substrates

    PubMed Central

    Deng, Wei; Zhang, Xiujuan; Pan, Huanhuan; Shang, Qixun; Wang, Jincheng; Zhang, Xiaohong; Zhang, Xiwei; Jie, Jiansheng

    2014-01-01

    Single-crystal organic nanostructures show promising applications in flexible and stretchable electronics, while their applications are impeded by the large incompatibility with the well-developed photolithography techniques. Here we report a novel two-step transfer printing (TTP) method for the construction of organic nanowires (NWs) based devices onto arbitrary substrates. Copper phthalocyanine (CuPc) NWs are first transfer-printed from the growth substrate to the desired receiver substrate by contact-printing (CP) method, and then electrode arrays are transfer-printed onto the resulting receiver substrate by etching-assisted transfer printing (ETP) method. By utilizing a thin copper (Cu) layer as sacrificial layer, microelectrodes fabricated on it via photolithography could be readily transferred to diverse conventional or non-conventional substrates that are not easily accessible before with a high transfer yield of near 100%. The ETP method also exhibits an extremely high flexibility; various electrodes such as Au, Ti, and Al etc. can be transferred, and almost all types of organic devices, such as resistors, Schottky diodes, and field-effect transistors (FETs), can be constructed on planar or complex curvilinear substrates. Significantly, these devices can function properly and exhibit closed or even superior performance than the device counterparts fabricated by conventional approach. PMID:24942458

  7. One-step fabrication of nickel nanocones by electrodeposition using CaCl2·2H2O as capping reagent

    NASA Astrophysics Data System (ADS)

    Lee, Jae Min; Jung, Kyung Kuk; Lee, Sung Ho; Ko, Jong Soo

    2016-04-01

    In this research, a method for the fabrication of nickel nanocones through the addition of CaCl2·2H2O to an electrodeposition solution was proposed. When electrodeposition was performed after CaCl2·2H2O addition, precipitation of the Ni ions onto the (2 0 0) crystal face was suppressed and anisotropic growth of the nickel electrodeposited structures was promoted. Sharper nanocones were produced with increasing concentration of CaCl2·2H2O added to the solution. Moreover, when temperature of the electrodeposition solutions approached 60 °C, the apex angle of the nanostructures decreased. In addition, the nanocones produced were applied to superhydrophobic surface modification using a plasma-polymerized fluorocarbon (PPFC) coating. When the solution temperature was maintained at 60 °C and the concentration of the added CaCl2·2H2O was 1.2 M or higher, the fabricated samples showed superhydrophobic surface properties. The proposed nickel nanocone formation method can be applied to various industrial fields that require metal nanocones, including superhydrophobic surface modification.

  8. Fundamental Study on the Fabrication of Inverted Planar Perovskite Solar Cells Using Two-Step Sequential Substrate Vibration-Assisted Spray Coating (2S-SVASC).

    PubMed

    Zabihi, Fatemeh; Ahmadian-Yazdi, Mohammad-Reza; Eslamian, Morteza

    2016-12-01

    In this paper, a scalable and fast process is developed and employed for the fabrication of the perovskite light harvesting layer in inverted planar heterojunction solar cell (FTO/PEDOT:PSS/CH3NH3PbI3-x Cl x /PCBM/Al). Perovskite precursor solutions are sprayed onto an ultrasonically vibrating substrate in two sequential steps via a process herein termed as the two-step sequential substrate vibration-assisted spray coating (2S-SVASC). The gentle imposed ultrasonic vibration on the substrate promotes droplet spreading and coalescence, surface wetting, evaporation, mixing of reagents, and uniform growth of perovskite nanocrystals. The role of the substrate temperature, substrate vibration intensity, and the time interval between the two sequential sprays are studied on the roughness, coverage, and crystalline structure of perovskite thin films. We demonstrate that a combination of a long time interval between spraying of precursor solutions (15 min), a high substrate temperature (120 °C), and a mild substrate vibration power (5 W) results in a favorable morphology and surface quality. The characteristics and performance of prepared perovskite thin films made via the 2S-SVASC technique are compared with those of the co-sprayed perovskite thin films. The maximum power conversion efficiency of 5.08 % on a 0.3-cm(2) active area is obtained for the device made via the scalable 2S-SVASC technique. PMID:26847697

  9. Fundamental Study on the Fabrication of Inverted Planar Perovskite Solar Cells Using Two-Step Sequential Substrate Vibration-Assisted Spray Coating (2S-SVASC).

    PubMed

    Zabihi, Fatemeh; Ahmadian-Yazdi, Mohammad-Reza; Eslamian, Morteza

    2016-12-01

    In this paper, a scalable and fast process is developed and employed for the fabrication of the perovskite light harvesting layer in inverted planar heterojunction solar cell (FTO/PEDOT:PSS/CH3NH3PbI3-x Cl x /PCBM/Al). Perovskite precursor solutions are sprayed onto an ultrasonically vibrating substrate in two sequential steps via a process herein termed as the two-step sequential substrate vibration-assisted spray coating (2S-SVASC). The gentle imposed ultrasonic vibration on the substrate promotes droplet spreading and coalescence, surface wetting, evaporation, mixing of reagents, and uniform growth of perovskite nanocrystals. The role of the substrate temperature, substrate vibration intensity, and the time interval between the two sequential sprays are studied on the roughness, coverage, and crystalline structure of perovskite thin films. We demonstrate that a combination of a long time interval between spraying of precursor solutions (15 min), a high substrate temperature (120 °C), and a mild substrate vibration power (5 W) results in a favorable morphology and surface quality. The characteristics and performance of prepared perovskite thin films made via the 2S-SVASC technique are compared with those of the co-sprayed perovskite thin films. The maximum power conversion efficiency of 5.08 % on a 0.3-cm(2) active area is obtained for the device made via the scalable 2S-SVASC technique.

  10. Nanostructured titanium-silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Bai, Long; Hang, Ruiqiang; Gao, Ang; Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin; Zhao, Lingzhou; Chu, Paul K.

    2015-11-01

    Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium-silver (Ti-Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti-Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti-Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti-Ag coatings.

  11. Large area fabrication of vertical silicon nanowire arrays by silver-assisted single-step chemical etching and their formation kinetics

    NASA Astrophysics Data System (ADS)

    Srivastava, Sanjay K.; Kumar, Dinesh; Schmitt, S. W.; Sood, K. N.; Christiansen, S. H.; Singh, P. K.

    2014-05-01

    Vertically aligned silicon nanowire (SiNW) arrays have been fabricated over a large area using a silver-assisted single-step electroless wet chemical etching (EWCE) method, which involves the etching of silicon wafers in aqueous hydrofluoric acid (HF) and silver nitrate (AgNO3) solution. A comprehensive systematic investigation on the influence of different parameters, such as the etching time (up to 15 h), solution temperature (10-80 °C), AgNO3 (5-200 mM) and HF (2-22 M) concentrations, and properties of the multi-crystalline silicon (mc-Si) wafers, is presented to establish a relationship of these parameters with the SiNW morphology. A linear dependence of the NW length on the etch time is obtained even at higher temperature (10-50 °C). The activation energy for the formation of SiNWs on Si(100) has been found to be equal to ˜0.51 eV . It has been shown for the first time that the surface area of the Si wafer exposed to the etching solution is an important parameter in determining the etching kinetics in the single-step process. Our results establish that single-step EWCE offers a wide range of parameters by means of which high quality vertical SiNWs can be produced in a very simple and controlled manner. A mechanism for explaining the influence of various parameters on the evolution of the NW structure is discussed. Furthermore, the SiNW arrays have extremely low reflectance (as low as <3% for Si(100) NWs and <12% for mc-Si NWs) compared to ˜35% for the polished surface in the 350-1000 nm wavelength range. The remarkably low reflection surface of SiNW arrays has great potential for use as an effective light absorber material in novel photovoltaic architectures, and other optoelectronic and photonic devices.

  12. Reduction of RIE induced damage of GaInAsP/InP DQW lasers fabricated by 2-step growth

    NASA Astrophysics Data System (ADS)

    Plumwongrot, D.; Kurokawa, M.; Okumura, T.; Nishimoto, Y.; Maruyama, T.; Nishiyama, N.; Arai, S.

    2008-02-01

    In order to realize low damage fine structuring processes for the low-dimensional quantum structures, we investigated a process for reducing the degradations of optical properties, which was induced during a reactive-ion-etching (RIE) process with CH 4/H II gas mixture in the quantum-well (QW) structures. Quantitative studies of optical degradation were carried out by photoluminescence (PL) and electroluminescence (EL) measurements. We introduced a thicker upper optical confinement layer (OCL) to protect the QWs from the RIE-plasma. In practical, for the PL measurement, twotypes of strain-compensated single-quantum-well (SC-SQW) structures were prepared for 40-nm-thick- and 80-nmthick- upper OCL wafers and covered by 20-nm-thick SiO II. After the samples were exposed to CH 4/H II-RIE for 5- minutes, a relatively stronger suppression of integral PL intensity as well as a spectral broadening was observed in the sample with 40-nm-thick OCL, while those did not change in the sample with 80-nm-thick OCL. For the EL measurements, using two types of SC-DQW structures, samples were exposed to CH 4/H II-RIE plasma for 5-minute and then re-grown for other layers to form high-mesa stripe laser structures (W s=1.5μm). As a result, the spontaneous emission efficiency of the lasers with 80-nm-thick OCL was almost 2 times higher than that of the lasers with 40-nmthick OCL. In addition, a lower threshold current as well as a higher differential quantum efficiency was obtained for the lasers with 80-nm-thick OCL , while that in lasers with 40-nm-thick OCL indicated poor efficiency and a slightly higher threshold.

  13. Mechanistic Insights into the Initiation Step of the Base Promoted Direct C-H Arylation of Benzene in the Presence of Additive.

    PubMed

    Patil, Mahendra

    2016-01-15

    The direct arylation of unactivated arenes is a very practical and highly convenient procedure for the construction of biaryl scaffolds. Recently, a direct arylation of unactivated benzene has been achieved in the presence of base (tBuOK or tBuONa) and organic additive such as 1,10-phenanthroline. However, details of intimate mechanism of reaction as well as the role of additive have remained elusive until date. The present work explores various mechanistic possibilities of the key electron transfer step of the reaction in order to identify a probable route for the initiation of phenyl radical from iodobenzene. A detailed DFT (M06-2X functional) investigation indicates that the reaction of additive and base can be crucial to generate an electron acceptor-donor pair that can facilitate electron transfer mechanism. This computational model provides a satisfactory explanation for experimental observations, clearly defining the roles of additive and base in the reaction.

  14. One-step fabrication of hollow-channel gold nanoflowers with excellent catalytic performance and large single-particle SERS activity.

    PubMed

    Ye, Sunjie; Benz, Felix; Wheeler, May C; Oram, Joseph; Baumberg, Jeremy J; Cespedes, Oscar; Christenson, Hugo K; Coletta, Patricia Louise; Jeuken, Lars J C; Markham, Alexander F; Critchley, Kevin; Evans, Stephen D

    2016-08-11

    Hollow metallic nanostructures have shown potential in various applications including catalysis, drug delivery and phototherapy, owing to their large surface areas, reduced net density, and unique optical properties. In this study, novel hollow gold nanoflowers (HAuNFs) consisting of an open hollow channel in the center and multiple branches/tips on the outer surface are fabricated for the first time, via a facile one-step synthesis using an auto-degradable nanofiber as a bifunctional template. The one-dimensional (1D) nanofiber acts as both a threading template as well as a promoter of the anisotropic growth of the gold crystal, the combination of which leads to the formation of HAuNFs with a hollow channel and nanospikes. The synergy of favorable structural/surface features, including sharp edges, open cavity and high-index facets, provides our HAuNFs with excellent catalytic performance (activity and cycling stability) coupled with large single-particle SERS activity (including ∼30 times of activity in ethanol electro-oxidation and ∼40 times of single-particle SERS intensity, benchmarked against similar-sized solid gold nanospheres with smooth surfaces, as well as retaining 86.7% of the initial catalytic activity after 500 cycles in ethanol electro-oxidation). This innovative synthesis gives a nanostructure of the geometry distinct from the template and is extendable to fabricating other systems for example, hollow-channel silver nanoflowers (HAgNFs). It thus provides an insight into the design of hollow nanostructures via template methods, and offers a versatile synthetic strategy for diverse metal nanomaterials suited for a broad range of applications.

  15. One-step in-mould modification of PDMS surfaces and its application in the fabrication of self-driven microfluidic channels.

    PubMed

    Fatona, Ayodele; Chen, Yang; Reid, Michael; Brook, Michael A; Moran-Mirabal, Jose M

    2015-11-21

    Poly(dimethylsiloxane) (PDMS) has become the material of choice for fabricating microfluidic channels for lab-on-a-chip applications. Key challenges that limit the use of PDMS in microfluidic applications are its hydrophobic nature, and the difficulty in obtaining stable surface modifications. Although a number of approaches exist to render PDMS hydrophilic, they suffer from reversion to hydrophobicity and, frequently, surface cracking or roughening. In this study, we describe a one-step in-mould method for the chemical modification of PDMS surfaces, and its use to assess the ability of different surfactants to render PDMS surfaces hydrophilic. Thin films of ionic and non-ionic surfactants were patterned into an array format, transferred onto silicone pre-polymer, and subsequently immobilized onto the PDMS surface during vulcanization. The hydrophilicity of the resulting surfaces was assessed by contact angle measurements. The wettability was observed to be dependent on the chemical structure of the surfactants, their concentration and interactions with PDMS. The morphology of modified PDMS surfaces and their change after wetting and drying cycles were visualized using atomic force microscopy. Our results show that while all surfactants tested can render PDMS surfaces hydrophilic through the in-mould modification, only those modified with PEG-PDMS-PEG copolymer surfactants were stable over wetting/dying cycles and heat treatments. Finally, the in-mould functionalization approach was used to fabricate self-driven microfluidic devices that exhibited steady flow rates, which could be tuned by the device geometry. It is anticipated that the in-mould method can be applied to a range of surface modifications for applications in analytical separations, biosensing, cell isolation and small molecule discovery. PMID:26400365

  16. One-step in-mould modification of PDMS surfaces and its application in the fabrication of self-driven microfluidic channels.

    PubMed

    Fatona, Ayodele; Chen, Yang; Reid, Michael; Brook, Michael A; Moran-Mirabal, Jose M

    2015-11-21

    Poly(dimethylsiloxane) (PDMS) has become the material of choice for fabricating microfluidic channels for lab-on-a-chip applications. Key challenges that limit the use of PDMS in microfluidic applications are its hydrophobic nature, and the difficulty in obtaining stable surface modifications. Although a number of approaches exist to render PDMS hydrophilic, they suffer from reversion to hydrophobicity and, frequently, surface cracking or roughening. In this study, we describe a one-step in-mould method for the chemical modification of PDMS surfaces, and its use to assess the ability of different surfactants to render PDMS surfaces hydrophilic. Thin films of ionic and non-ionic surfactants were patterned into an array format, transferred onto silicone pre-polymer, and subsequently immobilized onto the PDMS surface during vulcanization. The hydrophilicity of the resulting surfaces was assessed by contact angle measurements. The wettability was observed to be dependent on the chemical structure of the surfactants, their concentration and interactions with PDMS. The morphology of modified PDMS surfaces and their change after wetting and drying cycles were visualized using atomic force microscopy. Our results show that while all surfactants tested can render PDMS surfaces hydrophilic through the in-mould modification, only those modified with PEG-PDMS-PEG copolymer surfactants were stable over wetting/dying cycles and heat treatments. Finally, the in-mould functionalization approach was used to fabricate self-driven microfluidic devices that exhibited steady flow rates, which could be tuned by the device geometry. It is anticipated that the in-mould method can be applied to a range of surface modifications for applications in analytical separations, biosensing, cell isolation and small molecule discovery.

  17. One-step fabrication of hollow-channel gold nanoflowers with excellent catalytic performance and large single-particle SERS activity.

    PubMed

    Ye, Sunjie; Benz, Felix; Wheeler, May C; Oram, Joseph; Baumberg, Jeremy J; Cespedes, Oscar; Christenson, Hugo K; Coletta, Patricia Louise; Jeuken, Lars J C; Markham, Alexander F; Critchley, Kevin; Evans, Stephen D

    2016-08-11

    Hollow metallic nanostructures have shown potential in various applications including catalysis, drug delivery and phototherapy, owing to their large surface areas, reduced net density, and unique optical properties. In this study, novel hollow gold nanoflowers (HAuNFs) consisting of an open hollow channel in the center and multiple branches/tips on the outer surface are fabricated for the first time, via a facile one-step synthesis using an auto-degradable nanofiber as a bifunctional template. The one-dimensional (1D) nanofiber acts as both a threading template as well as a promoter of the anisotropic growth of the gold crystal, the combination of which leads to the formation of HAuNFs with a hollow channel and nanospikes. The synergy of favorable structural/surface features, including sharp edges, open cavity and high-index facets, provides our HAuNFs with excellent catalytic performance (activity and cycling stability) coupled with large single-particle SERS activity (including ∼30 times of activity in ethanol electro-oxidation and ∼40 times of single-particle SERS intensity, benchmarked against similar-sized solid gold nanospheres with smooth surfaces, as well as retaining 86.7% of the initial catalytic activity after 500 cycles in ethanol electro-oxidation). This innovative synthesis gives a nanostructure of the geometry distinct from the template and is extendable to fabricating other systems for example, hollow-channel silver nanoflowers (HAgNFs). It thus provides an insight into the design of hollow nanostructures via template methods, and offers a versatile synthetic strategy for diverse metal nanomaterials suited for a broad range of applications. PMID:27352044

  18. Fabrication of large-scale single-crystal bismuth telluride (Bi2Te3) nanosheet arrays by a single-step electrolysis process

    NASA Astrophysics Data System (ADS)

    Tsai, Hung-Wei; Wang, Tsang-Hsiu; Chan, Tsung-Cheng; Chen, Pei-Ju; Chung, Chih-Chun; Yaghoubi, Alireza; Liao, Chien-Neng; Diau, Eric Wei-Guang; Chueh, Yu-Lun

    2014-06-01

    Nanolizing of thermoelectric materials is one approach to reduce the thermal conductivity and hence enhance the figure of merit. Bismuth telluride (Bi2Te3)-based materials have excellent figure of merit at room temperature. For device applications, precise control and rapid fabrication for the nanostructure of thermoelectric materials are essential issues. In the present study, we demonstrate a one-step electrolysis process to directly form Bi2Te3 nanosheet arrays (NSAs) on the surface of bulk Bi2Te3 with controllable spacing distance and depth by tuning the applied bias and duration. The single sheet of NSAs reveals that the average thickness and electrical resistivity of single crystalline Bi2Te3 in composition are 399.8 nm and 137.34 μΩ m, respectively. The formation mechanism of NSAs has been proposed. A 1.12% efficiency of quantum dot-sensitized solar cells with Bi2Te3 NSAs for counter electrode has been demonstrated, indicating that Bi2Te3 NSAs from top-down processing with a high ratio of surface area to volume are a promising candidate for possible applications such as thermoelectrics, dye-sensitized solar cells (DSSCs), and lithium-ion batteries.Nanolizing of thermoelectric materials is one approach to reduce the thermal conductivity and hence enhance the figure of merit. Bismuth telluride (Bi2Te3)-based materials have excellent figure of merit at room temperature. For device applications, precise control and rapid fabrication for the nanostructure of thermoelectric materials are essential issues. In the present study, we demonstrate a one-step electrolysis process to directly form Bi2Te3 nanosheet arrays (NSAs) on the surface of bulk Bi2Te3 with controllable spacing distance and depth by tuning the applied bias and duration. The single sheet of NSAs reveals that the average thickness and electrical resistivity of single crystalline Bi2Te3 in composition are 399.8 nm and 137.34 μΩ m, respectively. The formation mechanism of NSAs has been proposed. A 1

  19. Two-step activation of paper batteries for high power generation: design and fabrication of biofluid- and water-activated paper batteries

    NASA Astrophysics Data System (ADS)

    Lee, Ki Bang

    2006-11-01

    Two-step activation of paper batteries has been successfully demonstrated to provide quick activation and to supply high power to credit card-sized biosystems on a plastic chip. A stack of a magnesium layer (an anode), a fluid guide (absorbent paper), a highly doped filter paper with copper chloride (a cathode) and a copper layer as a current collector is laminated between two transparent plastic films into a high power biofluid- and water-activated battery. The battery is activated by two-step activation: (1) after placing a drop of biofluid/water-based solution on the fluid inlet, the surface tension first drives the fluid to soak the fluid guide; (2) the fluid in the fluid guide then penetrates into the heavily doped filter paper with copper chloride to start the battery reaction. The fabricated half credit card-sized battery was activated by saliva, urine and tap water and delivered a maximum voltage of 1.56 V within 10 s after activation and a maximum power of 15.6 mW. When 10 kΩ and 1 KΩ loads are used, the service time with water, urine and saliva is measured as more than 2 h. An in-series battery of 3 V has been successfully tested to power two LEDs (light emitting diodes) and an electric driving circuit. As such, this high power paper battery could be integrated with on-demand credit card-sized biosystems such as healthcare test kits, biochips, lab-on-a-chip, DNA chips, protein chips or even test chips for water quality checking or chemical checking.

  20. Holographic fabrication of large-constant concave gratings for wide-range flat-field spectrometers with the addition of a concave lens.

    PubMed

    Zhou, Qian; Li, Xinghui; Ni, Kai; Tian, Rui; Pang, Jinchao

    2016-01-25

    We present a new design for the fabrication of concave gratings with large grating constants for flat-field miniature spectrometers with a wide spectral band. In this new design, one of the two optical paths for the holographic lithography of a curved grating structure with variable line spacing is modified by adding a concave lens in front of the point source. The addition of the concave lens allows the real point source, as well as the spatial filter for generating this point source, to be moved back. In this manner, the two spatial filters for generating two point sources are separated. Avoiding the physical conflict between these two spatial filters reduces the difficulty of fabricating large-constant concave gratings. Experimental results verify the feasibility of the proposed design in fabricating concave gratings with large grating constants. The resolution of a spectrometer using the fabricated concave grating is evaluated and found to be better than 1.1 nm across a spectral band ranging from 360 nm to 825 nm.

  1. One-step fabrication of triple-layered microcapsules by a tri-axial flow focusing device for microencapsulation of soluble drugs and imaging agents

    NASA Astrophysics Data System (ADS)

    Yuan, Shuai; Wu, Qiang; Lei, Fan; Li, Guangbin; Si, Ting; Xu, Ronald X.

    2016-04-01

    In this work, the microencapsulation of water-soluble drug (doxorubicin, Dox) and imaging agent (perfluorocarbon, PFC) is performed by a novel liquid driven tri-axial flow focusing (LDTFF) device. The formation of stable triple-layered cone-jet mode can be observed in the simple well-assembled LDTFF device, providing an easy approach to fabricate mono-disperse triple-layered microcapsules with high encapsulation efficiency, high throughput and low cost in just one step. The fluorescence images show that the microcapsules have a satisfactory core-shell structure. The SEM micrographs show spherical and smooth surface views of the triple-layered microcapsules after being stirred 72h to remove the organic solvent totally. The results of thermo-responsive release experiments of the produced triple-layered microcapsules show these multifunctional capsules can be well stimulated when the environment temperature is beyond 55 degree centigrade. In a word, this novel approach has a great potential in applications such as drug delivery and image-guided therapy.

  2. One-step fabrication of integrated disposable biosensor based on ADH/NAD+/meldola's blue/graphitized mesoporous carbons/chitosan nanobiocomposite for ethanol detection.

    PubMed

    Hua, Erhui; Wang, Li; Jing, Xiaoying; Chen, Changtao; Xie, Guoming

    2013-07-15

    A novel strategy to simplify the dehydrogenase-based electrochemical biosensor fabrication through one-step drop-coating nanobiocomposite on a screen printed electrode (SPE) was developed. The nanobiocomposite was prepared by successively adding graphitized mesoporous carbons (GMCs), meldola's blue (MDB), alcohol dehydrogenase (ADH) and cofactor nicotinamide adenine dinucleotide (NAD(+)) in chitosan (CS) solution. MDB/GMCs/CS film was prepared. Cyclic voltammetry measurements demonstrated that MDB was strongly adsorbed on GMCs. After optimizing the concentration of MDB and the working potential, the MDB/GMCs/CS film presented a fast amperometric response (5s), excellent sensitivity (10.36 nA μM(-1)), wide linear range (10-410 μM) toward NADH and without any other interference signals (such as AA, UA, DA, H2O2 and metal ions). Furthermore, concentrations of ADH and NAD(+) in nanobiocomposite and the detection conditions (temperature and pH) were also optimized. The constructed disposable ethanol biosensor showed an excellent linear response ranged from 0.5 to 15 mM with high sensitivity (67.28 nA mM(-1)) and a low limit of detection (80 μM) and a remarkable long-term stability (40 days). The intra-batch and inter-batch variation coefficients were both less than 5% (n=5). The ethanol recovery test demonstrated that the proposed biosensor offered a remarkable and accurate method for ethanol detection in the real blood samples.

  3. Three-dimensional Aerographite-GaN hybrid networks: Single step fabrication of porous and mechanically flexible materials for multifunctional applications

    PubMed Central

    Schuchardt, Arnim; Braniste, Tudor; Mishra, Yogendra K.; Deng, Mao; Mecklenburg, Matthias; Stevens-Kalceff, Marion A.; Raevschi, Simion; Schulte, Karl; Kienle, Lorenz; Adelung, Rainer; Tiginyanu, Ion

    2015-01-01

    Three dimensional (3D) elastic hybrid networks built from interconnected nano- and microstructure building units, in the form of semiconducting-carbonaceous materials, are potential candidates for advanced technological applications. However, fabrication of these 3D hybrid networks by simple and versatile methods is a challenging task due to the involvement of complex and multiple synthesis processes. In this paper, we demonstrate the growth of Aerographite-GaN 3D hybrid networks using ultralight and extremely porous carbon based Aerographite material as templates by a single step hydride vapor phase epitaxy process. The GaN nano- and microstructures grow on the surface of Aerographite tubes and follow the network architecture of the Aerographite template without agglomeration. The synthesized 3D networks are integrated with the properties from both, i.e., nanoscale GaN structures and Aerographite in the form of flexible and semiconducting composites which could be exploited as next generation materials for electronic, photonic, and sensors applications. PMID:25744694

  4. Numerical investigation of the mechanical properties of the additive manufactured bone scaffolds fabricated by FDM: The effect of layer penetration and post-heating.

    PubMed

    Naghieh, S; Karamooz Ravari, M R; Badrossamay, M; Foroozmehr, E; Kadkhodaei, M

    2016-06-01

    In recent years, thanks to additive manufacturing technology, researchers have gone towards the optimization of bone scaffolds for the bone reconstruction. Bone scaffolds should have appropriate biological as well as mechanical properties in order to play a decisive role in bone healing. Since the fabrication of scaffolds is time consuming and expensive, numerical methods are often utilized to simulate their mechanical properties in order to find a nearly optimum one. Finite element analysis is one of the most common numerical methods that is used in this regard. In this paper, a parametric finite element model is developed to assess the effects of layers penetration׳s effect on inter-layer adhesion, which is reflected on the mechanical properties of bone scaffolds. To be able to validate this model, some compression test specimens as well as bone scaffolds are fabricated with biocompatible and biodegradable poly lactic acid using fused deposition modeling. All these specimens are tested in compression and their elastic modulus is obtained. Using the material parameters of the compression test specimens, the finite element analysis of the bone scaffold is performed. The obtained elastic modulus is compared with experiment indicating a good agreement. Accordingly, the proposed finite element model is able to predict the mechanical behavior of fabricated bone scaffolds accurately. In addition, the effect of post-heating of bone scaffolds on their elastic modulus is investigated. The results demonstrate that the numerically predicted elastic modulus of scaffold is closer to experimental outcomes in comparison with as-built samples.

  5. Numerical investigation of the mechanical properties of the additive manufactured bone scaffolds fabricated by FDM: The effect of layer penetration and post-heating.

    PubMed

    Naghieh, S; Karamooz Ravari, M R; Badrossamay, M; Foroozmehr, E; Kadkhodaei, M

    2016-06-01

    In recent years, thanks to additive manufacturing technology, researchers have gone towards the optimization of bone scaffolds for the bone reconstruction. Bone scaffolds should have appropriate biological as well as mechanical properties in order to play a decisive role in bone healing. Since the fabrication of scaffolds is time consuming and expensive, numerical methods are often utilized to simulate their mechanical properties in order to find a nearly optimum one. Finite element analysis is one of the most common numerical methods that is used in this regard. In this paper, a parametric finite element model is developed to assess the effects of layers penetration׳s effect on inter-layer adhesion, which is reflected on the mechanical properties of bone scaffolds. To be able to validate this model, some compression test specimens as well as bone scaffolds are fabricated with biocompatible and biodegradable poly lactic acid using fused deposition modeling. All these specimens are tested in compression and their elastic modulus is obtained. Using the material parameters of the compression test specimens, the finite element analysis of the bone scaffold is performed. The obtained elastic modulus is compared with experiment indicating a good agreement. Accordingly, the proposed finite element model is able to predict the mechanical behavior of fabricated bone scaffolds accurately. In addition, the effect of post-heating of bone scaffolds on their elastic modulus is investigated. The results demonstrate that the numerically predicted elastic modulus of scaffold is closer to experimental outcomes in comparison with as-built samples. PMID:26874065

  6. 3D Printing, Additive Manufacturing, and Solid Freeform Fabrication: The Technologies of the Past, Present and Future

    NASA Astrophysics Data System (ADS)

    Beaman, Joseph

    2015-03-01

    Starting in the late 1980's, several new technologies were created that have the potential to revolutionize manufacturing. These technologies are, for the most part, additive processes that build up parts layer by layer. In addition, the processes that are being touted for hard-core manufacturing are primarily laser or e-beam based processes. This presentation gives a brief history of Additive Manufacturing and gives an assessment for these technologies. These technologies initially grew out of a commercial need for rapid prototyping. This market has a different requirement for process and quality control than traditional manufacturing. The relatively poor process control of the existing commercial Additive Manufacturing equipment is a vestige of this history. This presentation discusses this history and improvements in quality over time. The emphasis will be on Additive Manufacturing processes that are being considered for direct manufacturing, which is a different market than the 3D Printing ``Makerbot'' market. Topics discussed include past and present machine sensors, materials, and operational methods that were used in the past and those that are used today to create manufactured parts. Finally, a discussion of new methods and future directions of AM is presented.

  7. Fabrication of coatings and bulk products made of a nickel-based material by additive technology laser metal deposition

    NASA Astrophysics Data System (ADS)

    Gorunov, A. I.

    2016-01-01

    It is shown that products made of a nickel-based material can be formed by direct additive laser deposition. Ring samples with good antifriction properties are formed. The material after direct laser deposition is characterized by a heterogeneous structure: coarse inclusions with a high hardness are distributed in a softer matrix. Final laser treatment leads to the formation of a homogeneous microstructure and the refinement of second phases.

  8. The two-step positive temperature coefficient in resistance characteristics of n-(Ba, Pb)? ceramics created through inclusion of grain boundary modifier additives

    NASA Astrophysics Data System (ADS)

    Kutty, T. R. N.; Hari, N. S.

    1997-12-01

    Donor-doped n-0022-3727/30/24/015/img2 polycrystalline ceramics exhibit distinctly two-step positive temperature coefficient of resistance (PTCR) characteristics when formulated with suitable combinations of 0022-3727/30/24/015/img3 and 0022-3727/30/24/015/img4 as grain boundary modifiers by heterogeneous addition. 0022-3727/30/24/015/img3 or 0022-3727/30/24/015/img4 when added singularly resulted in either steep or broad PTCR jumps respectively across the phase transition. The two-step PTCR is attributed to the activation of the acceptor states, created through 0022-3727/30/24/015/img3 and 0022-3727/30/24/015/img4, for various temperature regimes above the Curie point 0022-3727/30/24/015/img9. The changing pattern of trap states is evident from the presence of 0022-3727/30/24/015/img10 - 0022-3727/30/24/015/img11 - 0022-3727/30/24/015/img12 type hole centres in the grain boundary layer regions, identified in the electron paramagnetic resonance (EPR) spectra. That charge redistribution occurs among the inter-band gap defect states on crossing the Curie temperature is substantiated by the temperature coefficient in the EPR results. Capacitance - voltage results clearly show that there is an increase in the density of trap states with the addition of 0022-3727/30/24/015/img3 and 0022-3727/30/24/015/img4. The spread in energy values of these trap states is evident from the large change in barrier height (0022-3727/30/24/015/img15 - 0.6 eV) between 500 and 650 K.

  9. Microstructural architecture developed in the fabrication of solid and open-cellular copper components by additive manufacturing using electron beam melting

    NASA Astrophysics Data System (ADS)

    Ramirez, Diana Alejandra

    The fabrication of Cu components were first built by additive manufacturing using electron beam melting (EBM) from low-purity, atomized Cu powder containing a high density of Cu2O precipitates leading to a novel example of precipitate-dislocation architecture. These microstructures exhibit cell-like arrays (1-3microm) in the horizontal reference plane perpendicular to the build direction with columnar-like arrays extending from ~12 to >60 microm in length and corresponding spatial dimensions of 1-3 microm. These observations were observed by the use of optical metallography, and scanning and transmission electron microscopy. The hardness measurements were taken both on the atomized powder and the Cu components. The hardness for these architectures ranged from ~HV 83 to 88, in contrast to the original Cu powder microindentation hardness of HV 72 and the commercial Cu base plate hardness of HV 57. These observations were utilized for the fabrication of open-cellular copper structures by additive manufacturing using EBM and illustrated the ability to fabricate some form of controlled microstructural architecture by EBM parameter alteration or optimizing. The fabrication of these structures ranged in densities from 0.73g/cm3 to 6.67g/cm3. These structures correspond to four different articulated mesh arrays. While these components contained some porosity as a consequence of some unmelted regions, the Cu2O precipitates also contributed to a reduced density. Using X-ray Diffraction showed the approximate volume fraction estimated to be ~2%. The addition of precipitates created in the EBM melt scan formed microstructural arrays which contributed to hardening contributing to the strength of mesh struts and foam ligaments. The measurements of relative stiffness versus relative density plots for Cu compared very closely with Ti-6Al-4V open cellular structures - both mesh and foams. The Cu reticulated mesh structures exhibit a slope of n = 2 in contrast to a slope of n = 2

  10. Tandem Solar Cells Using GaAs Nanowires on Si: Design, Fabrication, and Observation of Voltage Addition.

    PubMed

    Yao, Maoqing; Cong, Sen; Arab, Shermin; Huang, Ningfeng; Povinelli, Michelle L; Cronin, Stephen B; Dapkus, P Daniel; Zhou, Chongwu

    2015-11-11

    Multijunction solar cells provide us a viable approach to achieve efficiencies higher than the Shockley-Queisser limit. Due to their unique optical, electrical, and crystallographic features, semiconductor nanowires are good candidates to achieve monolithic integration of solar cell materials that are not lattice-matched. Here, we report the first realization of nanowire-on-Si tandem cells with the observation of voltage addition of the GaAs nanowire top cell and the Si bottom cell with an open circuit voltage of 0.956 V and an efficiency of 11.4%. Our simulation showed that the current-matching condition plays an important role in the overall efficiency. Furthermore, we characterized GaAs nanowire arrays grown on lattice-mismatched Si substrates and estimated the carrier density using photoluminescence. A low-resistance connecting junction was obtained using n(+)-GaAs/p(+)-Si heterojunction. Finally, we demonstrated tandem solar cells based on top GaAs nanowire array solar cells grown on bottom planar Si solar cells. The reported nanowire-on-Si tandem cell opens up great opportunities for high-efficiency, low-cost multijunction solar cells.

  11. Effect of pore size on bone ingrowth into porous titanium implants fabricated by additive manufacturing: An in vivo experiment.

    PubMed

    Taniguchi, Naoya; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Sasaki, Kiyoyuki; Otsuki, Bungo; Nakamura, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi; Matsuda, Shuichi

    2016-02-01

    Selective laser melting (SLM) is an additive manufacturing technique with the ability to produce metallic scaffolds with accurately controlled pore size, porosity, and interconnectivity for orthopedic applications. However, the optimal pore structure of porous titanium manufactured by SLM remains unclear. In this study, we evaluated the effect of pore size with constant porosity on in vivo bone ingrowth in rabbits into porous titanium implants manufactured by SLM. Three porous titanium implants (with an intended porosity of 65% and pore sizes of 300, 600, and 900μm, designated the P300, P600, and P900 implants, respectively) were manufactured by SLM. A diamond lattice was adapted as the basic structure. Their porous structures were evaluated and verified using microfocus X-ray computed tomography. Their bone-implant fixation ability was evaluated by their implantation as porous-surfaced titanium plates into the cortical bone of the rabbit tibia. Bone ingrowth was evaluated by their implantation as cylindrical porous titanium implants into the cancellous bone of the rabbit femur for 2, 4, and 8weeks. The average pore sizes of the P300, P600, and P900 implants were 309, 632, and 956μm, respectively. The P600 implant demonstrated a significantly higher fixation ability at 2weeks than the other implants. After 4weeks, all models had sufficiently high fixation ability in a detaching test. Bone ingrowth into the P300 implant was lower than into the other implants at 4weeks. Because of its appropriate mechanical strength, high fixation ability, and rapid bone ingrowth, our results indicate that the pore structure of the P600 implant is a suitable porous structure for orthopedic implants manufactured by SLM. PMID:26652423

  12. Effect of pore size on bone ingrowth into porous titanium implants fabricated by additive manufacturing: An in vivo experiment.

    PubMed

    Taniguchi, Naoya; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Sasaki, Kiyoyuki; Otsuki, Bungo; Nakamura, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi; Matsuda, Shuichi

    2016-02-01

    Selective laser melting (SLM) is an additive manufacturing technique with the ability to produce metallic scaffolds with accurately controlled pore size, porosity, and interconnectivity for orthopedic applications. However, the optimal pore structure of porous titanium manufactured by SLM remains unclear. In this study, we evaluated the effect of pore size with constant porosity on in vivo bone ingrowth in rabbits into porous titanium implants manufactured by SLM. Three porous titanium implants (with an intended porosity of 65% and pore sizes of 300, 600, and 900μm, designated the P300, P600, and P900 implants, respectively) were manufactured by SLM. A diamond lattice was adapted as the basic structure. Their porous structures were evaluated and verified using microfocus X-ray computed tomography. Their bone-implant fixation ability was evaluated by their implantation as porous-surfaced titanium plates into the cortical bone of the rabbit tibia. Bone ingrowth was evaluated by their implantation as cylindrical porous titanium implants into the cancellous bone of the rabbit femur for 2, 4, and 8weeks. The average pore sizes of the P300, P600, and P900 implants were 309, 632, and 956μm, respectively. The P600 implant demonstrated a significantly higher fixation ability at 2weeks than the other implants. After 4weeks, all models had sufficiently high fixation ability in a detaching test. Bone ingrowth into the P300 implant was lower than into the other implants at 4weeks. Because of its appropriate mechanical strength, high fixation ability, and rapid bone ingrowth, our results indicate that the pore structure of the P600 implant is a suitable porous structure for orthopedic implants manufactured by SLM.

  13. Variation in mechanical behavior due to different build directions of Titanium6Aluminum4Vanadium fabricated by electron beam additive manufacturing technology

    NASA Astrophysics Data System (ADS)

    Roy, Lalit

    Titanium has always been a metal of great interest since its discovery especially for critical applications because of its excellent mechanical properties such as light weight (almost half of that of the steel), low density (4.4 gm/cc) and high strength (almost similar to steel). It creates a stable and adherent oxide layer on its surface upon exposure to air or water which gives it a great resistance to corrosion and has made it a great choice for structures in severe corrosive environment and sea water. Its non-allergic property has made it suitable for biomedical application for manufacturing implants. Having a very high melting temperature, it has a very good potential for high temperature applications. But high production and processing cost has limited its application. Ti6Al4V is the most used titanium alloy for which it has acquired the title as `workhouse' of the Ti family. Additive layer Manufacturing (ALM) has brought revolution in manufacturing industries. Today, this additive manufacturing has developed into several methods and formed a family. This method fabricates a product by adding layer after layer as per the geometry given as input into the system. Though the conception was developed to fabricate prototypes and making tools initially, but its highly economic aspect i.e., very little waste material for less machining and comparatively lower production lead time, obviation of machine tools have drawn attention for its further development towards mass production. Electron Beam Melting (EBM) is the latest addition to ALM family developed by Arcam, ABRTM located in Sweden. The electron beam that is used as heat source melts metal powder to form layers. For this thesis work, three different types of specimens have been fabricated using EBM system. These specimens differ in regard of direction of layer addition. Mechanical properties such as ultimate tensile strength, elastic modulus and yield strength, have been measured and compared with standard data

  14. Evaluation of corn oil as an additive in the pre-enrichment step to increase recovery of Salmonella enterica from oregano.

    PubMed

    Jean-Gilles Beaubrun, Junia; Flamer, Marie-Laure; Addy, Nicole; Ewing, Laura; Gopinath, Gopal; Jarvis, Karen; Grim, Chris; Hanes, Darcy E

    2016-08-01

    Phenolic compounds associated with essential oils of spices and herbs possess a variety of antioxidant and antimicrobial properties that interfere with Salmonella detection from fresh and dried products. Finding a compound to neutralize the effect of these antimicrobial compounds, while allowing Salmonella growth during pre-enrichment, is a crucial step in both traditional pathogen isolation and molecular detection from these foods. This study evaluated the effectiveness of corn oil as a component of the pre-enrichment broth to counteract antimicrobial compounds properties and increase the recovery of Salmonella from spices. Oregano samples artificially contaminated with Salmonella enterica were pre-enriched in modified Buffered Peptone Water (mBPW) supplemented with and without 2% (vol/vol) corn oil respectively. Samples were incubated overnight at 37 °C. The results showed that recovery of Salmonella from oregano samples was increased by ≥50% when pre-enriched with corn oil. Serovars were confirmed using a PCR serotyping method. In addition, shot-gun metagenomics analyses demonstrated bacterial diversity and the effect of corn oil on the relative prevalence of Salmonella in the oregano samples. Modifying pre-enrichment broths with corn oil improved the detection and isolation of Salmonella from oregano, and may provide an alternative method for pathogen detection in dried food matrices such as spices. PMID:27052719

  15. Evaluation of corn oil as an additive in the pre-enrichment step to increase recovery of Salmonella enterica from oregano.

    PubMed

    Jean-Gilles Beaubrun, Junia; Flamer, Marie-Laure; Addy, Nicole; Ewing, Laura; Gopinath, Gopal; Jarvis, Karen; Grim, Chris; Hanes, Darcy E

    2016-08-01

    Phenolic compounds associated with essential oils of spices and herbs possess a variety of antioxidant and antimicrobial properties that interfere with Salmonella detection from fresh and dried products. Finding a compound to neutralize the effect of these antimicrobial compounds, while allowing Salmonella growth during pre-enrichment, is a crucial step in both traditional pathogen isolation and molecular detection from these foods. This study evaluated the effectiveness of corn oil as a component of the pre-enrichment broth to counteract antimicrobial compounds properties and increase the recovery of Salmonella from spices. Oregano samples artificially contaminated with Salmonella enterica were pre-enriched in modified Buffered Peptone Water (mBPW) supplemented with and without 2% (vol/vol) corn oil respectively. Samples were incubated overnight at 37 °C. The results showed that recovery of Salmonella from oregano samples was increased by ≥50% when pre-enriched with corn oil. Serovars were confirmed using a PCR serotyping method. In addition, shot-gun metagenomics analyses demonstrated bacterial diversity and the effect of corn oil on the relative prevalence of Salmonella in the oregano samples. Modifying pre-enrichment broths with corn oil improved the detection and isolation of Salmonella from oregano, and may provide an alternative method for pathogen detection in dried food matrices such as spices.

  16. Next Step for STEP

    SciTech Connect

    Wood, Claire; Bremner, Brenda

    2013-08-09

    The Siletz Tribal Energy Program (STEP), housed in the Tribe’s Planning Department, will hire a data entry coordinator to collect, enter, analyze and store all the current and future energy efficiency and renewable energy data pertaining to administrative structures the tribe owns and operates and for homes in which tribal members live. The proposed data entry coordinator will conduct an energy options analysis in collaboration with the rest of the Siletz Tribal Energy Program and Planning Department staff. An energy options analysis will result in a thorough understanding of tribal energy resources and consumption, if energy efficiency and conservation measures being implemented are having the desired effect, analysis of tribal energy loads (current and future energy consumption), and evaluation of local and commercial energy supply options. A literature search will also be conducted. In order to educate additional tribal members about renewable energy, we will send four tribal members to be trained to install and maintain solar panels, solar hot water heaters, wind turbines and/or micro-hydro.

  17. A robust super-paramagnetic TiO2:Fe3O4:Ag nanocomposite with enhanced photo and bio activities on polyester fabric via one step sonosynthesis.

    PubMed

    Harifi, Tina; Montazer, Majid

    2015-11-01

    High intensity ultrasound was used for the synthesis and simultaneous deposition of TiO2:Fe3O4:Ag nanocomposites on polyester surface providing a feasible route for imparting magnetic and enhanced antibacterial and self-cleaning activities with controllable hydrophilicity/hydrophobicity at low temperature. Synergistic impact of sonochemistry and physical effects of ultrasound originating from implosive collapse of bubbles were responsible for the formation and adsorption of nanomaterials on the fabric surface during ultrasound irradiation. The increase in photocatalytic activity of TiO2 was obtained attributing to the co-operation of iron oxide and silver nanoparticles nucleated on TiO2 surface boosting the electron-hole pair separation and prolonging their recombination rate. The process was further optimized in terms of reagents concentrations including Fe(2+)/TiO2 and Ag/TiO2 molar ratios using central composite design in order to achieve the best self-cleaning property of the treated fabric. The magnetic measurements indicated the super-paramagnetic behavior of the treated fabric with saturation magnetization of 4.5 (emu/g). Findings suggest the potential of the proposed facial method in producing an intelligent fabric with durable multi-functional activities that can be suitable for various applications including medical, military, bio-separation, bio-sensors, magneto graphic printing, magnetic screens and magnetic filters.

  18. A robust super-paramagnetic TiO2:Fe3O4:Ag nanocomposite with enhanced photo and bio activities on polyester fabric via one step sonosynthesis.

    PubMed

    Harifi, Tina; Montazer, Majid

    2015-11-01

    High intensity ultrasound was used for the synthesis and simultaneous deposition of TiO2:Fe3O4:Ag nanocomposites on polyester surface providing a feasible route for imparting magnetic and enhanced antibacterial and self-cleaning activities with controllable hydrophilicity/hydrophobicity at low temperature. Synergistic impact of sonochemistry and physical effects of ultrasound originating from implosive collapse of bubbles were responsible for the formation and adsorption of nanomaterials on the fabric surface during ultrasound irradiation. The increase in photocatalytic activity of TiO2 was obtained attributing to the co-operation of iron oxide and silver nanoparticles nucleated on TiO2 surface boosting the electron-hole pair separation and prolonging their recombination rate. The process was further optimized in terms of reagents concentrations including Fe(2+)/TiO2 and Ag/TiO2 molar ratios using central composite design in order to achieve the best self-cleaning property of the treated fabric. The magnetic measurements indicated the super-paramagnetic behavior of the treated fabric with saturation magnetization of 4.5 (emu/g). Findings suggest the potential of the proposed facial method in producing an intelligent fabric with durable multi-functional activities that can be suitable for various applications including medical, military, bio-separation, bio-sensors, magneto graphic printing, magnetic screens and magnetic filters. PMID:25899439

  19. Enhanced osteogenic activity and anti-inflammatory properties of Lenti-BMP-2-loaded TiO₂ nanotube layers fabricated by lyophilization following trehalose addition.

    PubMed

    Zhang, Xiaochen; Zhang, Zhiyuan; Shen, Gang; Zhao, Jun

    2016-01-01

    To enhance biocompatibility and osseointegration between titanium implants and surrounding bone tissue, numerous efforts have been made to modify the surface topography and composition of Ti implants. In this paper, Lenti-BMP-2-loaded TiO2 nanotube coatings were fabricated by lyophilization in the presence of trehalose to functionalize the surface. We characterized TiO2 nanotube layers in terms of the following: surface morphology; Lenti-BMP-2 and trehalose release; their ability to induce osteogenesis, proliferation, and anti-inflammation in vitro; and osseointegration in vivo. The anodized TiO2 nanotube surfaces exhibited an amorphous glassy matrix perpendicular to the Ti surface. Both Lenti-BMP-2 and trehalose showed sustained release over the course of 8 days. Results from real-time quantitative polymerase chain reaction studies demonstrated that lyophilized Lenti-BMP-2/TiO2 nanotubes constructed with trehalose (Lyo-Tre-Lenti-BMP-2) significantly promoted osteogenic differentiation of bone marrow stromal cells but not their proliferation. In addition, Lyo-Tre-Lenti-BMP-2 nanotubes effectively inhibited lipopolysaccharide-induced interleukin-1β and tumor necrosis factor-α production. In vivo, the formulation also promoted osseointegration. This study presents a promising new method for surface-modifying biomedical Ti-based implants to simultaneously enhance their osteogenic potential and anti-inflammatory properties, which can better satisfy clinical needs.

  20. Enhanced osteogenic activity and anti-inflammatory properties of Lenti-BMP-2-loaded TiO₂ nanotube layers fabricated by lyophilization following trehalose addition.

    PubMed

    Zhang, Xiaochen; Zhang, Zhiyuan; Shen, Gang; Zhao, Jun

    2016-01-01

    To enhance biocompatibility and osseointegration between titanium implants and surrounding bone tissue, numerous efforts have been made to modify the surface topography and composition of Ti implants. In this paper, Lenti-BMP-2-loaded TiO2 nanotube coatings were fabricated by lyophilization in the presence of trehalose to functionalize the surface. We characterized TiO2 nanotube layers in terms of the following: surface morphology; Lenti-BMP-2 and trehalose release; their ability to induce osteogenesis, proliferation, and anti-inflammation in vitro; and osseointegration in vivo. The anodized TiO2 nanotube surfaces exhibited an amorphous glassy matrix perpendicular to the Ti surface. Both Lenti-BMP-2 and trehalose showed sustained release over the course of 8 days. Results from real-time quantitative polymerase chain reaction studies demonstrated that lyophilized Lenti-BMP-2/TiO2 nanotubes constructed with trehalose (Lyo-Tre-Lenti-BMP-2) significantly promoted osteogenic differentiation of bone marrow stromal cells but not their proliferation. In addition, Lyo-Tre-Lenti-BMP-2 nanotubes effectively inhibited lipopolysaccharide-induced interleukin-1β and tumor necrosis factor-α production. In vivo, the formulation also promoted osseointegration. This study presents a promising new method for surface-modifying biomedical Ti-based implants to simultaneously enhance their osteogenic potential and anti-inflammatory properties, which can better satisfy clinical needs. PMID:26869786

  1. Effect of titanium addition on the thermal properties of diamond/cu-ti composites fabricated by pressureless liquid-phase sintering technique.

    PubMed

    Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

    2014-01-01

    In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m · K for 50 vol% diamond/Cu-0.6 at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained.

  2. Enhanced osteogenic activity and anti-inflammatory properties of Lenti-BMP-2-loaded TiO2 nanotube layers fabricated by lyophilization following trehalose addition

    PubMed Central

    Zhang, Xiaochen; Zhang, Zhiyuan; Shen, Gang; Zhao, Jun

    2016-01-01

    To enhance biocompatibility and osseointegration between titanium implants and surrounding bone tissue, numerous efforts have been made to modify the surface topography and composition of Ti implants. In this paper, Lenti-BMP-2-loaded TiO2 nanotube coatings were fabricated by lyophilization in the presence of trehalose to functionalize the surface. We characterized TiO2 nanotube layers in terms of the following: surface morphology; Lenti-BMP-2 and trehalose release; their ability to induce osteogenesis, proliferation, and anti-inflammation in vitro; and osseointegration in vivo. The anodized TiO2 nanotube surfaces exhibited an amorphous glassy matrix perpendicular to the Ti surface. Both Lenti-BMP-2 and trehalose showed sustained release over the course of 8 days. Results from real-time quantitative polymerase chain reaction studies demonstrated that lyophilized Lenti-BMP-2/TiO2 nanotubes constructed with trehalose (Lyo-Tre-Lenti-BMP-2) significantly promoted osteogenic differentiation of bone marrow stromal cells but not their proliferation. In addition, Lyo-Tre-Lenti-BMP-2 nanotubes effectively inhibited lipopolysaccharide-induced interleukin-1β and tumor necrosis factor-α production. In vivo, the formulation also promoted osseointegration. This study presents a promising new method for surface-modifying biomedical Ti-based implants to simultaneously enhance their osteogenic potential and anti-inflammatory properties, which can better satisfy clinical needs. PMID:26869786

  3. Fabrication of boron articles

    DOEpatents

    Benton, Samuel T.

    1976-01-01

    This invention is directed to the fabrication of boron articles by a powder metallurgical method wherein the articles are of a density close to the theoretical density of boron and are essentially crackfree. The method comprises the steps of admixing 1 to 10 weight percent carbon powder with amorphous boron powder, cold pressing the mixture and then hot pressing the cold pressed compact into the desired article. The addition of the carbon to the mixture provides a pressing aid for inhibiting the cracking of the hot pressed article and is of a concentration less than that which would cause the articles to possess significant concentrations of boron carbide.

  4. Security: Step by Step

    ERIC Educational Resources Information Center

    Svetcov, Eric

    2005-01-01

    This article provides a list of the essential steps to keeping a school's or district's network safe and sound. It describes how to establish a security architecture and approach that will continually evolve as the threat environment changes over time. The article discusses the methodology for implementing this approach and then discusses the…

  5. A Unique Approach to Generate Self-Aligned SiO2/Ge/SiO2/SiGe Gate-Stacking Heterostructures in a Single Fabrication Step

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Ting; Yang, Kuo-Ching; Hsu, Ting-Chia; Liao, Po-Hsiang; George, Thomas; Li, Pei-Wen

    2015-05-01

    We report a first-of-its-kind, unique approach for generating a self-aligned, gate-stacking heterostructure of Ge quantum dot (QD)/SiO2/SiGe shell on Si in a single fabrication step. The 4-nm-thick SiO2 layer between the Ge QD and SiGe shell fabricated during the single-step process is the result of an exquisitely controlled dynamic balance between the fluxes of oxygen and silicon interstitials. The high-quality interface properties of our "designer" heterostructure are evidenced by the low interface trap density of as low as 2-4 × 1011 cm-2 eV-1 and superior transfer characteristics measured for Ge-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Thanks to the very thin interfacial SiO2 layer, carrier storage within the Ge QDs with good memory endurance was established under relatively low-voltage programming/erasing conditions. We hope that our unique self-aligned, gate-stacking heterostructure provides an effective approach for the production of next-generation, high-performance Ge gate/SiO2/SiGe channel MOSFETs.

  6. A Unique Approach to Generate Self-Aligned SiO2/Ge/SiO2/SiGe Gate-Stacking Heterostructures in a Single Fabrication Step.

    PubMed

    Lai, Wei-Ting; Yang, Kuo-Ching; Hsu, Ting-Chia; Liao, Po-Hsiang; George, Thomas; Li, Pei-Wen

    2015-01-01

    We report a first-of-its-kind, unique approach for generating a self-aligned, gate-stacking heterostructure of Ge quantum dot (QD)/SiO2/SiGe shell on Si in a single fabrication step. The 4-nm-thick SiO2 layer between the Ge QD and SiGe shell fabricated during the single-step process is the result of an exquisitely controlled dynamic balance between the fluxes of oxygen and silicon interstitials. The high-quality interface properties of our "designer" heterostructure are evidenced by the low interface trap density of as low as 2-4 × 10(11) cm(-2) eV(-1) and superior transfer characteristics measured for Ge-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Thanks to the very thin interfacial SiO2 layer, carrier storage within the Ge QDs with good memory endurance was established under relatively low-voltage programming/erasing conditions. We hope that our unique self-aligned, gate-stacking heterostructure provides an effective approach for the production of next-generation, high-performance Ge gate/SiO2/SiGe channel MOSFETs.

  7. Two-step approach of fabrication of three-dimensional MnO2-graphene-carbon nanotube hybrid as a binder-free supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Xiong, Chuanyin; Li, Tiehu; Dang, Alei; Zhao, Tingkai; Li, Hao; Lv, Huiqin

    2016-02-01

    This paper describes the fabrication and characterization of a three-dimensional (3D) MnO2-graphene (GR)-CNT hybrid obtained by combining electrochemical deposition (ELD)-electrophoretic deposition (EPD) and chemical vapor deposition (CVD). Firstly, 3D MnO2-graphene oxide (GO) is fabricated via ELD-EPD. Secondly, the catalyst and xylene are mixed with solution of certain concentration. Thirdly, catalyst is loaded on the surface of MnO2-GO when the solution is sprayed into the furnace. Forth, MnO2-GO is restored to MnO2-GR at high temperature, meanwhile, MnO2-GR is served as a substrate to grow CNT, which is beneficial to provide high speed channel for carrier and obtain pseudocapacitance of MnO2. The as-prepared hybrid is characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray Diffraction (XRD) and Raman spectroscopy (Raman), and their supercapacitor properties are also investigated. The results show that a high specific capacitance of 330.75 F g-1 and high energy density of 36.68 Wh kg-1 while maintaining high power density of 8000 W kg-1 at a scan rate of 200 mV s-1. Furthermore, the hybrid displays a high specific capacitance of 187.53 F g-1 at ultrahigh scan rate of 400 mV s-1. These attractive results demonstrate that the hybrid is a promising electrode material for high performance supercapacitors.

  8. A combined electron beam/optical lithography process step for the fabrication of sub-half-micron-gate-length MMIC chips

    NASA Technical Reports Server (NTRS)

    Sewell, James S.; Bozada, Christopher A.

    1994-01-01

    Advanced radar and communication systems rely heavily on state-of-the-art microelectronics. Systems such as the phased-array radar require many transmit/receive (T/R) modules which are made up of many millimeter wave - microwave integrated circuits (MMIC's). The heart of a MMIC chip is the Gallium Arsenide (GaAs) field-effect transistor (FET). The transistor gate length is the critical feature that determines the operating frequency of the radar system. A smaller gate length will typically result in a higher frequency. In order to make a phased array radar system economically feasible, manufacturers must be capable of producing very large quantities of small-gate-length MMIC chips at a relatively low cost per chip. This requires the processing of a large number of wafers with a large number of chips per wafer, minimum processing time, and a very high chip yield. One of the bottlenecks in the fabrication of MIMIC chips is the transistor gate definition. The definition of sub-half-micron gates for GaAs-based field-effect transistors is generally performed by direct-write electron beam lithography (EBL). Because of the throughput limitations of EBL, the gate-layer fabrication is conventionally divided into two lithographic processes where EBL is used to generate the gate fingers and optical lithography is used to generate the large-area gate pads and interconnects. As a result, two complete sequences of resist application, exposure, development, metallization and lift-off are required for the entire gate structure. We have baselined a hybrid process, referred to as EBOL (electron beam/optical lithography), in which a single application of a multi-level resist is used for both exposures. The entire gate structure, (gate fingers, interconnects and pads), is then formed with a single metallization and lift-off process. The EBOL process thus retains the advantages of the high-resolution E-beam lithography and the high throughput of optical lithography while essentially

  9. One-step fabrication of copper sulfide nanoparticles decorated on graphene sheets as highly stable and efficient counter electrode for CdS-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Hessein, Amr; Wang, Feiju; Masai, Hirokazu; Matsuda, Kazunari; Abd El-Moneim, Ahmed

    2016-11-01

    Quantum-dot-sensitized solar cells (QDSSCs) are thin-film photovoltaics and highly promising as next-generation solar cells owing to their high theoretical efficiency, easy fabrication process, and low production cost. However, the practical photoconversion efficiencies (PCEs) of QDSSCs are still far below the theoretically estimated value owing to the lack of an applicable design of the materials and electrodes. In this work, we developed a highly stable and efficient counter electrode (CE) from copper sulfide nanocrystals and reduced graphene oxide (Cu x S@RGO) for QDSSC applications. The Cu x S@RGO electrocatalyst was successfully prepared by a facile one-pot hydrothermal method, then directly applied to a fluorine-doped tin oxide (FTO)-coated glass substrate by the simple drop-casting technique. Owing to the synergistic effect between Cu x S nanocrystals and conductive RGO sheets, the Cu x S@RGO CE showed high electrocatalytic activity for polysulfide electrolyte reduction. A CdS QDSSC based on the Cu x S@RGO CE yielded a high and reproducible PCE of 2.36%, exceeding those of 1.57 and 1.33% obtained with the commonly used Cu2S/brass and Pt CEs, respectively. Moreover, the QDSSC with the Cu x S@RGO CE showed excellent photostability in a light-soaking test without any obvious decay in the photocurrent, whereas the cell based on the Cu2S/brass CE was severely degraded.

  10. Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

    2014-10-01

    A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m2/g according to Brunauer-Emmett-Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ΔG and positive ΔH. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

  11. Electrical Characterization of a Thiol SAM on Gold as a First Step for the Fabrication of Immunosensors based on a Quartz Crystal Microbalance

    PubMed Central

    Tlili, Asma; Abdelghani, Adnane; Hleli, Salwa; Maaref, Mhamed A.

    2004-01-01

    In order to develop a robust biosensor based on quartz crystal microbalance technique for antigen detection, a control of the steps of the surface functionalization has been performed by impedance spectroscopy. The gold electrode is functionalized with the self-assembled monolayer technique. The high insulating properties of the acidic thiol monolayer has been characterized with cyclic voltammetry and impedance spectroscopy. The modified surface is activated with N-hydroxysuccinimide(NHS) and 1-(3-(dimethylamino)propyl)-3-ethylcarbodimide hydrochloride(EDC) cross-linker for antibody coupling. The non-specific sites are blocked with bovin serum albumine molecules. Different concentrations of antigen can be detected with a good reversibility in real time with the quartz crystal microbalance.

  12. One-step fabrication of highly stable, superhydrophobic composites from controllable and low-cost PMHS/TEOS sols for efficient oil cleanup.

    PubMed

    Guo, Ping; Zhai, Shangru; Xiao, Zuoyi; An, Qingda

    2015-05-15

    Facing the issues of significant increase of industrial oily wastewater and frequent accident of oil spills, the developing of efficient and affordable absorbents for improving oil pollution is of practical significance. Herein, several superhydrophobic and superoleophilic materials, utilizing filter paper, filter cloth and polyester sponge as substrates, through facile coating of hybrid SiO2 colloid particles from controllable PMHS-TEOS sol system were presented. These methyl-modified particles not only provided hierarchical micro/nano-scale structure with distinct roughness, but also largely lowered the surface energy of the coated substances, leading to excellent superhydrophobic and superoleophilic surfaces. The modified filter cloths could be applied for oil/water separation owing to the flexible and foldable property; sponges could efficiently absorb oil or organic solvents in situ on account of its low density and high porosity, and meanwhile the absorbed oil could be easily recollected by simple squeezing. It is worth mentioning that both modified filter cloths and sponges exhibited excellent selectivity, high efficiency, outstanding rapidity and remarkable recyclability. More importantly, after treatment of 100 abrasion cycles with metal scalpel and strongly acidic and basic water droplets, the whole WCA values of resultant filter cloths still maintained superhydrophobic character (>150°), illuminating the charming mechanical and chemical stability of sol-gel processed coating with hierarchical roughness and covalently bonded methyl groups. Combining controllable fabrication process and cheap raw precursors, this method enables scalable manufacturing of stable and superhydrophobic substances, which are promising in practical applications involved in oil/water separation and oil sorption.

  13. One-step fabrication of large-area ultrathin MoS2 nanofilms with high catalytic activity for photovoltaic devices.

    PubMed

    Liang, Jia; Li, Jia; Zhu, Hongfei; Han, Yuxiang; Wang, Yanrong; Wang, Caixing; Jin, Zhong; Zhang, Gengmin; Liu, Jie

    2016-09-21

    Here we report a facile one-step solution-phase process to directly grow ultrathin MoS2 nanofilms on a transparent conductive glass as a novel high-performance counter electrode for dye-sensitized solar cells. After an appropriate reaction time, the entire surface of the conductive glass substrate was uniformly covered by ultrathin MoS2 nanofilms with a thickness of only several stacked layers. Electrochemical impedance spectroscopy and cyclic voltammetry reveal that the MoS2 nanofilms possess excellent catalytic activity towards tri-iodide reduction. When used in dye-sensitized solar cells, the MoS2 nanofilms show an impressive energy conversion efficiency of 8.3%, which is higher than that of a Pt-based electrode and very promising to be a desirable alternative counter electrode. Considering their ultrathin thickness, superior catalytic activity, simple preparation process and low cost, the as-prepared MoS2 nanofilms with high photovoltaic performance are expected to be widely employed in dye-sensitized solar cells. PMID:27545846

  14. One-step fabrication of large-area ultrathin MoS2 nanofilms with high catalytic activity for photovoltaic devices.

    PubMed

    Liang, Jia; Li, Jia; Zhu, Hongfei; Han, Yuxiang; Wang, Yanrong; Wang, Caixing; Jin, Zhong; Zhang, Gengmin; Liu, Jie

    2016-09-21

    Here we report a facile one-step solution-phase process to directly grow ultrathin MoS2 nanofilms on a transparent conductive glass as a novel high-performance counter electrode for dye-sensitized solar cells. After an appropriate reaction time, the entire surface of the conductive glass substrate was uniformly covered by ultrathin MoS2 nanofilms with a thickness of only several stacked layers. Electrochemical impedance spectroscopy and cyclic voltammetry reveal that the MoS2 nanofilms possess excellent catalytic activity towards tri-iodide reduction. When used in dye-sensitized solar cells, the MoS2 nanofilms show an impressive energy conversion efficiency of 8.3%, which is higher than that of a Pt-based electrode and very promising to be a desirable alternative counter electrode. Considering their ultrathin thickness, superior catalytic activity, simple preparation process and low cost, the as-prepared MoS2 nanofilms with high photovoltaic performance are expected to be widely employed in dye-sensitized solar cells.

  15. Effects of the space for wash materials on sulcus depth reproduction with addition-curing silicone using two-step putty-wash technique.

    PubMed

    Shiozawa, Maho; Takahashi, Hidekazu; Finger, Werner J; Iwasaki, Naohiko

    2013-01-01

    Aim of this study was to investigate effects of space thickness and consistency of wash materials on sulcus depth reproduction with silicone impressions, low (L), medium (M), and very high consistency (VH), using two-step putty-wash technique. Impressions were taken from truncated cones with 50-, 100-, or 200-μm-wide sulci, using the combinations L+VH or M+VH and different space thickness for wash materials: 2 mm (ST2), 1 mm (ST1), and approximately 25 μm (ST0.025). Sulcus depth reproduction tended to increase with increasing sulcus width. Sulcus reproduction of ST0.025 was deeper than those of the other groups. At 100- and 200-μm sulcus widths, sulcus reproductions of ST1 and ST2 with L+HV were deeper than with M+HV. Regardless of consistency, the thin spacer produced deep reproduction. Adequate 0.5 mm sulcus reproductions were obtained with 100 and 200 μm wide sulci and 1- and 2-mm spacer widths, combined with low consistency impression material.

  16. Fabrication of top-contact pentacene-based organic thin-film transistors with short channels using two-step SU8/poly(vinyl alcohol) lift-off photolithography process

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Lin, Wei-Chun; Lee, Cheng-Chieh; Lin, Yu-Zuo; Huang, Bohr-Ran

    2016-02-01

    We propose a two-step SU8/poly(vinyl alcohol) (PVA) lift-off photolithography scheme for fabricating top-contact pentacene-based organic thin-film transistors (OTFTs) with small channels. The bilayer of PVA and SU8 will not damage the pentacene channel layer in the lift-off photolithography process used in forming the patterned pentacene channel layer and source/drain metal electrodes. We demonstrate a device that not only obtains a 5 µm short channel length for source/drain metal-electrode patterning but also avoids fringe current resulting from pentacene channel layer patterning. The field-effect mobility and threshold voltage of the pentacene-based OTFTs were changed from 0.29 to 0.12 cm2 V-1 s-1 and from -5.74 to -3.19 V by varying the channel length from 50 to 5 µm, respectively. The proposed scheme is a good candidate for use in the design and fabrication of high-performance short-channel organic electronics.

  17. Addition of equilibrium air to an upwind Navier-Stokes code and other first steps toward a more generalized flow solver

    NASA Technical Reports Server (NTRS)

    Rosen, Bruce S.

    1991-01-01

    An upwind three-dimensional volume Navier-Stokes code is modified to facilitate modeling of complex geometries and flow fields represented by proposed National Aerospace Plane concepts. Code enhancements include an equilibrium air model, a generalized equilibrium gas model and several schemes to simplify treatment of complex geometric configurations. The code is also restructured for inclusion of an arbitrary number of independent and dependent variables. This latter capability is intended for eventual use to incorporate nonequilibrium/chemistry gas models, more sophisticated turbulence and transition models, or other physical phenomena which will require inclusion of additional variables and/or governing equations. Comparisons of computed results with experimental data and results obtained using other methods are presented for code validation purposes. Good correlation is obtained for all of the test cases considered, indicating the success of the current effort.

  18. A DFT study on the NHC catalysed Michael addition of enols to α,β-unsaturated acyl-azoliums. A base catalysed C-C bond-formation step.

    PubMed

    Domingo, Luis R; Sáez, José A; Arnó, Manuel

    2014-02-14

    The NHC catalysed nucleophilic additions of enols to α,β-unsaturated acyl-azolium intermediates have been investigated using DFT methods at the MPWB1K/6-31G** computational level. In the direct and the conjugate additions, formation of a hydrogen bond (HB) with the carboxyl oxygen is not sufficient to favour the C-C bond formation as a consequence of the low nucleophilic character of enols. Interestingly, when enols form a HB with the chloride counterion, the activation energies associated with the conjugate addition decrease as a consequence of the increased nucleophilic character of enols and the increased electrophilic character of the 'acyl-azolium + Cl' ion pair. Analysis of the DFT reactivity indices allows establishing a base catalysed C-C bond-formation step promoted by the chloride counterion. PMID:24343422

  19. A DFT study on the NHC catalysed Michael addition of enols to α,β-unsaturated acyl-azoliums. A base catalysed C-C bond-formation step.

    PubMed

    Domingo, Luis R; Sáez, José A; Arnó, Manuel

    2014-02-14

    The NHC catalysed nucleophilic additions of enols to α,β-unsaturated acyl-azolium intermediates have been investigated using DFT methods at the MPWB1K/6-31G** computational level. In the direct and the conjugate additions, formation of a hydrogen bond (HB) with the carboxyl oxygen is not sufficient to favour the C-C bond formation as a consequence of the low nucleophilic character of enols. Interestingly, when enols form a HB with the chloride counterion, the activation energies associated with the conjugate addition decrease as a consequence of the increased nucleophilic character of enols and the increased electrophilic character of the 'acyl-azolium + Cl' ion pair. Analysis of the DFT reactivity indices allows establishing a base catalysed C-C bond-formation step promoted by the chloride counterion.

  20. One-step thermal-treatment route to fabricate well-dispersed ZnO nanocrystals on nitrogen-doped graphene for enhanced electrochemiluminescence and ultrasensitive detection of pentachlorophenol.

    PubMed

    Jiang, Ding; Du, Xiaojiao; Liu, Qian; Zhou, Lei; Qian, Jing; Wang, Kun

    2015-02-11

    Heteroatom doping enables graphene with novel properties and thus may broaden the potential of graphene-based materials. In this paper, novel ZnO-nanocrystal-decorated nitrogen-doped graphene (N-GR) composites were prepared through a one-step thermal-treatment route using glycine as the nitrogen source. ZnO nanocrystals with a size about 8 nm were well-dispersed and tightly anchored on the N-GR sheet. Compared with ZnO-nanocrystal-decorated undoped graphene, the ZnO/N-GR nanocomposites could not only enhance the electrochemiluminescence (ECL) intensity by 4.3-fold but also moved the ECL onset potential positively for ∼200 mV. All these results could be ascribed to the presence of nitrogen in graphene which decreased the barrier of ZnO nanocrystals reduction. Furthermore, the ECL sensor based on ZnO/N-GR nanocomposites was fabricated for the ultrasensitive detection of pentachlorophenol (PCP). This recyclable and eco-friendly sensor has excellent performances including wide linear range (0.5 pM to ∼61.1 nM), low detection limit (0.16 pM, S/N=3), good selectivity, and stability, which is a promising sensor for practical application in environment analysis.

  1. Production of 7α,15α-diOH-DHEA from dehydroepiandrosterone by Colletotrichum lini ST-1 through integrating glucose-feeding with multi-step substrate addition strategy.

    PubMed

    Li, Cong; Li, Hui; Sun, Jin; Zhang, XinYue; Shi, Jinsong; Xu, Zhenghong

    2016-08-01

    Hydroxylation of dehydroepiandrosterone (DHEA) to 3β,7α,15α-trihydroxy-5-androstene-17-one (7α,15α-diOH-DHEA) by Colletotrichum lini ST-1 is an essential step in the synthesis of many steroidal drugs, while low DHEA concentration and 7α,15α-diOH-DHEA production are tough problems to be solved urgently in industry. In this study, the significant improvement of 7α,15α-diOH-DHEA yield in 5-L stirred fermenter with 15 g/L DHEA was achieved. To maintain a sufficient quantity of glucose for the bioconversion, glucose of 15 g/L was fed at 18 h, the 7α,15α-diOH-DHEA yield and dry cell weight were increased by 17.7 and 30.9 %, respectively. Moreover, multi-step DHEA addition strategy was established to diminish DHEA toxicity to C. lini, and the 7α,15α-diOH-DHEA yield raised to 53.0 %. Further, a novel strategy integrating glucose-feeding with multi-step addition of DHEA was carried out and the product yield increased to 66.6 %, which was the highest reported 7α,15α-diOH-DHEA production in 5-L stirred fermenter. Meanwhile, the conversion course was shortened to 44 h. This strategy would provide a possible way in enhancing the 7α,15α-diOH-DHEA yield in pharmaceutical industry.

  2. Dependence of Device Characteristics of Bulk-Heterojunction Organic Thin-Film Solar Cells on Concentration of Glycerol and Sorbitol Addition in Pedot:. PSS Solutions for Fabricating Buffer Layers

    NASA Astrophysics Data System (ADS)

    Yamaki, Yusuke; Marumoto, Kazuhiro; Fujimori, Takuya; Mori, Tatsuo

    We have investigated the dependence of device characteristics of bulk-heterojunction organic thin-film solar cells on the concentration of glycerol and sorbitol addition in poly(3,4-ethylenedioxy thiophene):poly(4-styrene sulfonate) (PEDOT:PSS) solutions for fabricating buffer layers. The device structure is ITO/buffer/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM)/Al. Glycerol addition is effective for increasing power conversion efficiency (PCE) from 1.25 to 1.41% because of the increase in short-circuit current density (Jsc) without decreasing open-circuit voltage (Voc). On the other hand, sorbitol addition decreases PCE from 1.25 to 1.04%, owing to the decrease in Voc. This difference in Voc behavior is ascribed to different work function of PEDOT:PSS with glycerol and sorbitol treatment.

  3. Micromachine Wedge Stepping Motor

    SciTech Connect

    Allen, J.J.; Schriner, H.K.

    1998-11-04

    A wedge stepping motor, which will index a mechanism, has been designed and fabricated in the surface rnicromachine SUMMiT process. This device has demonstrated the ability to index one gear tooth at a time with speeds up to 205 teeth/see. The wedge stepper motor has the following features, whi:h will be useful in a number of applications. o The ability to precisely position mechanical components. . Simple pulse signals can be used for operation. o Only 2 drive signals are requixed for operation. o Torque and precision capabilities increase with device size . The device to be indexed is restrained at all times by the wedge shaped tooth that is used for actuation. This paper will discuss the theory of operation and desi=m of the wedge stepping motor. The fabrication and testing of I he device will also be presented.

  4. Enhancement on wettability and intermetallic compound formation with an addition of Al on Sn-0.7Cu lead-free solder fabricated via powder metallurgy method

    NASA Astrophysics Data System (ADS)

    Adli, Nisrin; Razak, Nurul Razliana Abdul; Saud, Norainiza

    2016-07-01

    Due to the toxicity of lead (Pb), the exploration of another possibility for lead-free solder is necessary. Nowadays, SnCu alloys are being established as one of the lead-free solder alternatives. In this study, Sn-0.7Cu lead-free solder with an addition of 1wt% and 5wt% Al were investigated by using powder metallurgy method. The effect of Al addition on the wettability and intermetallic compound thickness (IMC) of Sn-0.7Cu-Al lead-free solder were appraised. Results showed that Al having a high potential to enhance Sn-0.7Cu lead-free solder due to its good wetting and reduction of IMC thickness. The contact angle and IMC of the Sn-0.7Cu-Al lead-free solder were decreased by 14.32% and 40% as the Al content increased from 1 wt% to 5 wt%.

  5. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-07-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning.

  6. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure.

    PubMed

    Yang, Y; Sumption, M D; Collings, E W

    2016-07-13

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning.

  7. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    PubMed Central

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-01-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning. PMID:27406904

  8. Towards monomaterial p-n junctions: Single-step fabrication of tin oxide films and their non-destructive characterisation by angle-dependent X-ray photoelectron spectroscopy

    SciTech Connect

    Krzywiecki, Maciej; Sarfraz, Adnan; Erbe, Andreas

    2015-12-07

    The application of a non-destructive method for characterization of electronic structure of an ultra-thin SnO{sub 1step fabrication of materials with ambipolar doping.

  9. PHOEBE - step by step manual

    NASA Astrophysics Data System (ADS)

    Zasche, P.

    2016-03-01

    An easy step-by-step manual of PHOEBE is presented. It should serve as a starting point for the first time users of PHOEBE analyzing the eclipsing binary light curve. It is demonstrated on one particular detached system also with the downloadable data and the whole procedure is described easily till the final trustworthy fit is being reached.

  10. Electron Beam Freeform Fabrication

    NASA Video Gallery

    Electron Beam Freeform Fabrication (EBF3) is a process by which NASA hopes to build metal parts in zero gravity environments. It's a layer-additive process that uses an electron beam and a solid wi...

  11. Centro-Apical Self-Organization of Organic Semiconductors in a Line-Printed Organic Semiconductor: Polymer Blend for One-Step Printing Fabrication of Organic Field-Effect Transistors

    PubMed Central

    Jin Lee, Su; Kim, Yong-Jae; Young Yeo, So; Lee, Eunji; Sun Lim, Ho; Kim, Min; Song, Yong-Won; Cho, Jinhan; Ah Lim, Jung

    2015-01-01

    Here we report the first demonstration for centro-apical self-organization of organic semiconductors in a line-printed organic semiconductor: polymer blend. Key feature of this work is that organic semiconductor molecules were vertically segregated on top of the polymer phase and simultaneously crystallized at the center of the printed line pattern after solvent evaporation without an additive process. The thickness and width of the centro-apically segregated organic semiconductor crystalline stripe in the printed blend pattern were controlled by varying the relative content of the organic semiconductors, printing speed, and solution concentrations. The centro-apical self-organization of organic semiconductor molecules in a printed polymer blend may be attributed to the combination of an energetically favorable vertical phase-separation and hydrodynamic fluids inside the droplet during solvent evaporation. Finally, a centro-apically phase-separated bilayer structure of organic semiconductor: polymer blend was successfully demonstrated as a facile method to form the semiconductor and dielectric layer for OFETs in one- step. PMID:26359068

  12. Centro-Apical Self-Organization of Organic Semiconductors in a Line-Printed Organic Semiconductor: Polymer Blend for One-Step Printing Fabrication of Organic Field-Effect Transistors.

    PubMed

    Lee, Su Jin; Kim, Yong-Jae; Yeo, So Young; Lee, Eunji; Lim, Ho Sun; Kim, Min; Song, Yong-Won; Cho, Jinhan; Lim, Jung Ah

    2015-01-01

    Here we report the first demonstration for centro-apical self-organization of organic semiconductors in a line-printed organic semiconductor: polymer blend. Key feature of this work is that organic semiconductor molecules were vertically segregated on top of the polymer phase and simultaneously crystallized at the center of the printed line pattern after solvent evaporation without an additive process. The thickness and width of the centro-apically segregated organic semiconductor crystalline stripe in the printed blend pattern were controlled by varying the relative content of the organic semiconductors, printing speed, and solution concentrations. The centro-apical self-organization of organic semiconductor molecules in a printed polymer blend may be attributed to the combination of an energetically favorable vertical phase-separation and hydrodynamic fluids inside the droplet during solvent evaporation. Finally, a centro-apically phase-separated bilayer structure of organic semiconductor: polymer blend was successfully demonstrated as a facile method to form the semiconductor and dielectric layer for OFETs in one- step.

  13. Fabrication of micro-optical devices

    NASA Technical Reports Server (NTRS)

    Anderson, W. W.; Marley, J.; Gal, George; Purdy, Don

    1993-01-01

    We have fabricated a variety of micro-optic components including Fresnel and non-Frensel lenses, off-axis and dispersive lenses with binary stepped contours, and analog contours. Process details for all lens designs fabricated are given including multistep photolithography for binary fabrication and grayscale mask photolithography for analog fabrication. Reactive ion etching and ion beam milling are described for the binary fabrication process, while ion beam milling was used for the analog fabrication process. Examples of micro-optic components fabricated in both Si and CdTe substrates are given.

  14. Quality assurance and yield improvement in photomask fabrication

    NASA Astrophysics Data System (ADS)

    Yamauchi, Takashi

    2000-07-01

    Photomask used in aspect of semiconductor is called on 'No.0 process in wafer' or 'Key-parts', so that we are required to make it with Hi-reliability and Hi-quality level. On the other hand, its problem that cost of Photomask Fabrication jumps because machine price, inspection tool, and inspection steps in leading-edge are increasing. For decreasing what we call 'cost of quality assurance', its policy is significant that quality management in photomask production line is equal quality assurance in photomask, in addition improvement process capability. This report clears the requirement of customer, specification, and the problem, introduces quality assurance and yield improvement in photomask fabrication.

  15. Stepped nozzle

    DOEpatents

    Sutton, George P.

    1998-01-01

    An insert which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment.

  16. Stepped nozzle

    DOEpatents

    Sutton, G.P.

    1998-07-14

    An insert is described which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment. 5 figs.

  17. Fabric fastenings

    NASA Technical Reports Server (NTRS)

    Walen, E D; Fisher, R T

    1920-01-01

    The study of aeronautical fabrics has led to a consideration of the best methods of attaching and fastening together such materials. This report presents the results of an investigation upon the proper methods of attaching fabrics to airplane wings. The methods recommended in this report have been adopted by the military services.

  18. Wire grid polarizers fabricated by low angle deposition

    NASA Astrophysics Data System (ADS)

    Watts, M. P. C.; Little, M.; Egan, E.; Hochbaum, A.; Johns, C.; Stephansen, S.

    2013-03-01

    Oblique angle metal deposition has been combined with high aspect ratio imprinted structures to create wire grid polarizers (WGP's) for use as polarization recyclers in liquid crystal displays. The optical results for the oblique deposition WGP show contrast comparable to a conventionally etched WGP. In addition, the WGP showed improved spectral and spatial uniformity as compared to a multilayer reflective polarizer. The next steps to the fabrication of meter sized WGP are proposed.

  19. Parallel fabrication of nanogap electrodes.

    PubMed

    Johnston, Danvers E; Strachan, Douglas R; Johnson, A T Charlie

    2007-09-01

    We have developed a technique for simultaneously fabricating large numbers of nanogaps in a single processing step using feedback-controlled electromigration. Parallel nanogap formation is achieved by a balanced simultaneous process that uses a novel arrangement of nanoscale shorts between narrow constrictions where the nanogaps form. Because of this balancing, the fabrication of multiple nanoelectrodes is similar to that of a single nanogap junction. The technique should be useful for constructing complex circuits of molecular-scale electronic devices.

  20. Criticality Calculations for Step-2 GPHS Modules

    NASA Astrophysics Data System (ADS)

    Lipinski, Ronald J.; Hensen, Danielle L.

    2008-01-01

    The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) will use an improved version of the General Purpose Heat Source (GPHS) module as its source of thermal power. This new version, referred to as the Step-2 GPHS Module, has additional and thicker layers of carbon fiber material (Fine Weaved Pierced Fabric) for increased strength over the original GPHS module. The GPHS uses alpha decay of 238Pu in the oxide form as the primary source of heat, and small amounts of other actinides are also present in the oxide fuel. Criticality calculations have been performed by previous researchers on the original version of the GPHS module (Step 0). This paper presents criticality calculations for the present Step-2 version. The Monte Carlo N-Particle eXtended code (MCNPX) was used for these calculations. Numerous configurations of GPHS module arrays surrounded by wet sand and other materials (to reflect the neutrons back into the stack with minimal absorption) were modeled. For geometries with eight GPHS modules (from a single MMRTG) surrounded by wet sand, the configuration is extremely sub-critical; keff is about 0.3. It requires about 1000 GPHS modules (from 125 MMRTGs) in a close-spaced stack to approach criticality (keff = 1.0) when surrounded by wet sand. The effect of beryllium in the MMRTG was found to be relatively small.

  1. Criticality calculations for Step-2 GPHS modules.

    SciTech Connect

    Hensen, Danielle Lynn; Lipinski, Ronald J.

    2007-08-01

    The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) will use an improved version of the General Purpose Heat Source (GPHS) module as its source of thermal power. This new version, referred to as the Step-2 GPHS Module, has additional and thicker layers of carbon fiber material (Fine Weaved Pierced Fabric) for increased strength over the original GPHS module. The GPHS uses alpha decay of {sup 238}Pu in the oxide form as the primary source of heat, and small amounts of other actinides are also present in the oxide fuel. Criticality calculations have been performed by previous researchers on the original version of the GPHS module (Step 0). This paper presents criticality calculations for the present Step-2 version. The Monte Carlo N-Particle eXtended code (MCNPX) was used for these calculations. Numerous configurations of GPHS module arrays surrounded by wet sand and other materials (to reflect the neutrons back into the stack with minimal absorption) were modeled. For geometries with eight GPHS modules (from a single MMRTG) surrounded by wet sand, the configuration is extremely sub-critical; k{sub eff} is about 0.3. It requires about 1000 GPHS modules (from 125 MMRTGs) in a close-spaced stack to approach criticality (k{sub eff} = 1.0) when surrounded by wet sand. The effect of beryllium in the MMRTG was found to be relatively small.

  2. Criticality Calculations for Step-2 GPHS Modules

    SciTech Connect

    Lipinski, Ronald J.; Hensen, Danielle L.

    2008-01-21

    The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) will use an improved version of the General Purpose Heat Source (GPHS) module as its source of thermal power. This new version, referred to as the Step-2 GPHS Module, has additional and thicker layers of carbon fiber material (Fine Weaved Pierced Fabric) for increased strength over the original GPHS module. The GPHS uses alpha decay of {sup 238}Pu in the oxide form as the primary source of heat, and small amounts of other actinides are also present in the oxide fuel. Criticality calculations have been performed by previous researchers on the original version of the GPHS module (Step 0). This paper presents criticality calculations for the present Step-2 version. The Monte Carlo N-Particle eXtended code (MCNPX) was used for these calculations. Numerous configurations of GPHS module arrays surrounded by wet sand and other materials (to reflect the neutrons back into the stack with minimal absorption) were modeled. For geometries with eight GPHS modules (from a single MMRTG) surrounded by wet sand, the configuration is extremely sub-critical; k{sub eff} is about 0.3. It requires about 1000 GPHS modules (from 125 MMRTGs) in a close-spaced stack to approach criticality (k{sub eff} = 1.0) when surrounded by wet sand. The effect of beryllium in the MMRTG was found to be relatively small.

  3. Precise Fabrication of Electromagnetic-Levitation Coils

    NASA Technical Reports Server (NTRS)

    Ethridge, E.; Curreri, P.; Theiss, J.; Abbaschian, G.

    1985-01-01

    Winding copper tubing on jig ensures reproducible performance. Sequence of steps insures consistent fabrication of levitation-and-melting coils. New method enables technician to produce eight coils per day, 95 percent of them acceptable. Method employs precise step-by-step procedure on specially designed wrapping and winding jig.

  4. Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors.

    PubMed

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio; Markos, Christos; Nielsen, Kristian; Rasmussen, Henrik K; Bang, Ole

    2016-01-25

    We have fabricated the first single-mode step-index and humidity insensitive polymer optical fiber operating in the 850 nm wavelength ranges. The step-index preform is fabricated using injection molding, which is an efficient method for cost effective, flexible and fast preparation of the fiber preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured POFs. PMID:26832507

  5. Deformation grating fabrication technique based on the solvent-assisted microcontact molding.

    PubMed

    Dai, Xianglu; Xie, Huimin; Wang, Huaixi

    2014-10-20

    A deformation grating fabrication technique based on solvent-assisted microcontact molding (SAMIM) is reported in this paper. The fabrication process can be divided into three steps: imprinting a grating on a medium polymer substrate (MPS) by SAMIM, coating a thin metal film on the MPS, and transferring the film to the measured surface. In order to increase the stiffness of the elastic mold without decreasing its conformal contact formation ability, a re-useable, glass-embedded polydimethylsiloxane (PDMS) mold is used. In addition, a characterization method based on the Fourier transform and phase analysis is proposed to check the quality of the fabricated grating. Verified by experiment, the proposed fabrication technique can fabricate a high-frequency large-area grating on different specimens, which can be a qualified deformation sensor for the moiré method. PMID:25402792

  6. Single-step direct fabrication of luminescent Cu-doped Zn(x)Cd(1-x)S quantum dot thin films via a molecular precursor solution approach and their application in luminescent, transparent, and conductive thin films.

    PubMed

    Chen, Yanyan; Li, Shenjie; Huang, Lijian; Pan, Daocheng

    2014-08-21

    Luminescent Cu-doped ZnxCd1-xS quantum dot thin films have been directly fabricated via a facile solution method in open air. Cu2O, ZnO, and Cd(OH)2 were used as starting materials, and 3-mercaptopropionic acid was used as the capping agent. The effects of Cu dopant concentration, sintering temperature, and sintering time on the photoluminescence properties of Cu-doped ZnxCd1-xS nanocrystal thin films have been systematically investigated. As-prepared quantum dot thin films exhibit tunable emission covering the whole visible light region and the absolute photoluminescence quantum yields can reach as high as 25.5%, which have high potential for applications in luminescent, transparent, and conductive thin films.

  7. Photoactive rolled-up TiO2 microtubes: fabrication, characterization and applications† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c4tc00796d Click here for additional data file.

    PubMed Central

    Marz, Sonja M.; Soler, Lluís; Madani, Abbas; Jorgensen, Matthew R.; Schmidt, Oliver G.

    2014-01-01

    Because of its unique properties, titania (TiO2) represents a promising candidate in a wide variety of research fields. In this paper, some of the properties and potential applications of titania within rolled-up nanotechnology are explored. It is shown how the structural and optical properties of rolled titania microtubes can be controlled by properly tuning the microfabrication parameters. The rolling up of titania films on different sacrificial layers and containing different shapes, achieving a control on the diameter of the fabricated titania microtubes, is presented. In order to obtain the more photoactive crystalline form of titania, one during-fabrication and two post-fabrication methods are demonstrated. Interesting applications in the fields of photocatalysis and photonics are suggested: the use of titania rolled-up microtubes as micromotors and optical microresonators is presented. PMID:25580249

  8. SPAR-H Step-by-Step Guidance

    SciTech Connect

    April M. Whaley; Dana L. Kelly; Ronald L. Boring; William J. Galyean

    2012-06-01

    Step-by-step guidance was developed recently at Idaho National Laboratory for the US Nuclear Regulatory Commission on the use of the Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) method for quantifying Human Failure Events (HFEs). This work was done to address SPAR-H user needs, specifically requests for additional guidance on the proper application of various aspects of the methodology. This paper overviews the steps of the SPAR-H analysis process and highlights some of the most important insights gained during the development of the step-by-step directions. This supplemental guidance for analysts is applicable when plant-specific information is available, and goes beyond the general guidance provided in existing SPAR-H documentation. The steps highlighted in this paper are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff.

  9. Asymmetric Superhydrophobic/Superhydrophilic Cotton Fabrics Designed by Spraying Polymer and Nanoparticles.

    PubMed

    Sasaki, Kaichi; Tenjimbayashi, Mizuki; Manabe, Kengo; Shiratori, Seimei

    2016-01-13

    Inspired by the special wettability of certain natural life forms, such as the high water repellency of lotus leaves, many researchers have attempted to impart superhydrophobic properties to fabrics in academic and industrial contexts. Recently, a new switching system of wettability has inspired a strong demand for advanced coatings, even though their fabrication remains complex and costly. Here, cotton fabrics with asymmetric wettability (one face with natural superhydrophilicity and one face with superhydrophobicity) were fabricated by one-step spraying of a mixture of biocompatible commercial materials, hydrophobic SiO2 nanoparticles and ethyl-α-cyanoacrylate superglue. Our approach involves controlling the permeation of the fabric coatings by changing the distance between the fabric and the sprayer, to make one side superhydrophobic and the other side naturally superhydrophilic. As a result, the superhydrophobic side, with its high mechanical durability, exhibited a water contact angle of 154° and sliding angle of 16°, which meets the requirement for self-cleaning ability of surfaces. The opposite side exhibited high water absorption ability owing to the natural superhydrophilic property of the fabric. In addition, the designed cotton fabrics had blood absorption and clotting abilities on the superhydrophilic side, while the superhydrophobic side prevented water and blood permeation without losing the natural breathability of the cotton. These functions may be useful in the design of multifunctional fabrics for medical applications.

  10. Fabrication of diamond shells

    DOEpatents

    Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard

    2016-11-01

    A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.

  11. Unexpected Accumulation of ncm5U and ncm5s2U in a trm9 Mutant Suggests an Additional Step in the Synthesis of mcm5U and mcm5s2U

    PubMed Central

    Chen, Changchun; Huang, Bo; Anderson, James T.; Byström, Anders S.

    2011-01-01

    Background Transfer RNAs are synthesized as a primary transcript that is processed to produce a mature tRNA. As part of the maturation process, a subset of the nucleosides are modified. Modifications in the anticodon region often modulate the decoding ability of the tRNA. At position 34, the majority of yeast cytosolic tRNA species that have a uridine are modified to 5-carbamoylmethyluridine (ncm5U), 5-carbamoylmethyl-2′-O-methyluridine (ncm5Um), 5-methoxycarbonylmethyl-uridine (mcm5U) or 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U). The formation of mcm5 and ncm5 side chains involves a complex pathway, where the last step in formation of mcm5 is a methyl esterification of cm5 dependent on the Trm9 and Trm112 proteins. Methodology and Principal Findings Both Trm9 and Trm112 are required for the last step in formation of mcm5 side chains at wobble uridines. By co-expressing a histidine-tagged Trm9p together with a native Trm112p in E. coli, these two proteins purified as a complex. The presence of Trm112p dramatically improves the methyltransferase activity of Trm9p in vitro. Single tRNA species that normally contain mcm5U or mcm5s2U nucleosides were isolated from trm9Δ or trm112Δ mutants and the presence of modified nucleosides was analyzed by HPLC. In both mutants, mcm5U and mcm5s2U nucleosides are absent in tRNAs and the major intermediates accumulating were ncm5U and ncm5s2U, not the expected cm5U and cm5s2U. Conclusions Trm9p and Trm112p function together at the final step in formation of mcm5U in tRNA by using the intermediate cm5U as a substrate. In tRNA isolated from trm9Δ and trm112Δ strains, ncm5U and ncm5s2U nucleosides accumulate, questioning the order of nucleoside intermediate formation of the mcm5 side chain. We propose two alternative explanations for this observation. One is that the intermediate cm5U is generated from ncm5U by a yet unknown mechanism and the other is that cm5U is formed before ncm5U and mcm5U. PMID:21687733

  12. Hydraulic Design of Stepped Spillways Workshop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stepped chutes and spillways are commonly used for routing discharges during flood events. In addition, stepped chutes are used for overtopping protection of earthen embankments. Stepped spillways provide significant energy dissipation due to its stepped feature; as a result, the stilling basin as...

  13. Step-step interactions on GaAs (110) nanopatterns

    SciTech Connect

    Galiana, B.; Benedicto, M.; Tejedor, P.

    2013-01-14

    The step-step interactions on vicinal GaAs (110) surface patterns have been extracted from the quantitative analysis of the terrace width distribution (TWD). We have specifically studied the interactions in near-equilibrium faceting and kinetics-driven step bunching and meandering formed by spontaneous self-organization or through the modification of GaAs growth kinetics by atomic hydrogen. We show that the experimental TWDs determined from atomic force microscopy measurements can be accurately described by a weighed sum of a generalized Wigner distribution and several Gaussians. The results of our calculations indicate that straight facets are formed during high temperature homoepitaxy due to attractive interactions between [110] steps. At low temperatures, steady state attractive interactions in [110] step bunches are preceded by a transition regime dominated by entropic and energetic repulsions between meandering [11n]-type steps (n {>=} 2), whose population density exceeds that of the [110] bunched steps. In addition, it has been found that atomic H reduces the attractive interactions between [110] bunched steps and enhances entropic and dipole-induced energetic repulsions between H-terminated [11n] steps through the inhibition of As-As bond formation at step edges. Our analysis has evidenced a correlation between the value of the adjustable parameter that accounts in our model for the specific weight of the secondary peaks in the TWD ({beta}) and the extent of transverse meandering on the vicinal surface.

  14. Precise carbon control of fabricated stainless steel

    DOEpatents

    Nilsen, R.J.

    1975-12-01

    A process is described for controlling the carbon content of fabricated stainless steel components including the steps of heat treating the component in hydrogen atmospheres of varying dewpoints and carbon potentials.

  15. Mask fabrication process

    DOEpatents

    Cardinale, Gregory F.

    2000-01-01

    A method for fabricating masks and reticles useful for projection lithography systems. An absorber layer is conventionally patterned using a pattern and etch process. Following the step of patterning, the entire surface of the remaining top patterning photoresist layer as well as that portion of an underlying protective photoresist layer where absorber material has been etched away is exposed to UV radiation. The UV-exposed regions of the protective photoresist layer and the top patterning photoresist layer are then removed by solution development, thereby eliminating the need for an oxygen plasma etch and strip and chances for damaging the surface of the substrate or coatings.

  16. A novel method of fabricating integrated FETs for MEMS applications.

    SciTech Connect

    Okandan, Murat; Bennett, Reid Stuart; Draper, Bruce Leroy; Mani, Seethambal S.

    2003-07-01

    This paper demonstrates a simple technique for building n-channel MOSFETs and complex micromechanical systems simultaneously instead of serially, allowing a more straightforward integration of complete systems. The fabrication sequence uses few additional process steps and only one additional masking layer compared to a MEMS-only technology. The process flow forms the MOSFET gate electrode using the first level of mechanical polycrystalline silicon, while the MOSFET source and drain regions are formed by dopant diffusions into the substrate from subsequent levels of heavily doped poly that is used for mechanical elements. The process yields devices with good, repeatable electrical characteristics suitable for a wide range of digital and analog applications.

  17. Nanoimprint lithography for nanodevice fabrication

    NASA Astrophysics Data System (ADS)

    Barcelo, Steven; Li, Zhiyong

    2016-09-01

    Nanoimprint lithography (NIL) is a compelling technique for low cost nanoscale device fabrication. The precise and repeatable replication of nanoscale patterns from a single high resolution patterning step makes the NIL technique much more versatile than other expensive techniques such as e-beam or even helium ion beam lithography. Furthermore, the use of mechanical deformation during the NIL process enables grayscale lithography with only a single patterning step, not achievable with any other conventional lithography techniques. These strengths enable the fabrication of unique nanoscale devices by NIL for a variety of applications including optics, plasmonics and even biotechnology. Recent advances in throughput and yield in NIL processes demonstrate the potential of being adopted for mainstream semiconductor device fabrication as well.

  18. Fabrication Technology

    SciTech Connect

    Blaedel, K.L.

    1993-03-01

    The mission of the Fabrication Technology thrust area is to have an adequate base of manufacturing technology, not necessarily resident at Lawrence Livermore National Laboratory (LLNL), to conduct the future business of LLNL. The specific goals continue to be to (1) develop an understanding of fundamental fabrication processes; (2) construct general purpose process models that will have wide applicability; (3) document findings and models in journals; (4) transfer technology to LLNL programs, industry, and colleagues; and (5) develop continuing relationships with the industrial and academic communities to advance the collective understanding of fabrication processes. The strategy to ensure success is changing. For technologies in which they are expert and which will continue to be of future importance to LLNL, they can often attract outside resources both to maintain their expertise by applying it to a specific problem and to help fund further development. A popular vehicle to fund such work is the Cooperative Research and Development Agreement with industry. For technologies needing development because of their future critical importance and in which they are not expert, they use internal funding sources. These latter are the topics of the thrust area. Three FY-92 funded projects are discussed in this section. Each project clearly moves the Fabrication Technology thrust area towards the goals outlined above. They have also continued their membership in the North Carolina State University Precision Engineering Center, a multidisciplinary research and graduate program established to provide the new technologies needed by high-technology institutions in the US. As members, they have access to and use of the results of their research projects, many of which parallel the precision engineering efforts at LLNL.

  19. 3-dimensional fabrication of soft energy harvesters

    NASA Astrophysics Data System (ADS)

    McKay, Thomas; Walters, Peter; Rossiter, Jonathan; O'Brien, Benjamin; Anderson, Iain

    2013-04-01

    Dielectric elastomer generators (DEG) provide an opportunity to harvest energy from low frequency and aperiodic sources. Because DEG are soft, deformable, high energy density generators, they can be coupled to complex structures such as the human body to harvest excess mechanical energy. However, DEG are typically constrained by a rigid frame and manufactured in a simple planar structure. This planar arrangement is unlikely to be optimal for harvesting from compliant and/or complex structures. In this paper we present a soft generator which is fabricated into a 3 Dimensional geometry. This capability will enable the 3-dimensional structure of a dielectric elastomer to be customised to the energy source, allowing efficient and/or non-invasive coupling. This paper demonstrates our first 3 dimensional generator which includes a diaphragm with a soft elastomer frame. When the generator was connected to a self-priming circuit and cyclically inflated, energy was accumulated in the system, demonstrated by an increased voltage. Our 3D generator promises a bright future for dielectric elastomers that will be customised for integration with complex and soft structures. In addition to customisable geometries, the 3D printing process may lend itself to fabricating large arrays of small generator units and for fabricating truly soft generators with excellent impedance matching to biological tissue. Thus comfortable, wearable energy harvesters are one step closer to reality.

  20. Thermoelectric Device Fabrication Using Thermal Spray and Laser Micromachining

    NASA Astrophysics Data System (ADS)

    Tewolde, Mahder; Fu, Gaosheng; Hwang, David J.; Zuo, Lei; Sampath, Sanjay; Longtin, Jon P.

    2016-02-01

    Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are used in many engineering applications such as vehicle and industrial waste-heat recovery systems to provide electrical power, improve operating efficiency and reduce costs. State-of-art TEG manufacturing is based on prefabricated materials and a labor-intensive process involving soldering, epoxy bonding, and mechanical clamping for assembly. This reduces their durability and raises costs. Additive manufacturing technologies, such as thermal spray, present opportunities to overcome these challenges. In this work, TEGs have been fabricated for the first time using thermal spray technology and laser micromachining. The TEGs are fabricated directly onto engineering component surfaces. First, current fabrication techniques of TEGs are presented. Next, the steps required to fabricate a thermal spray-based TEG module, including the formation of the metallic interconnect layers and the thermoelectric legs are presented. A technique for bridging the air gap between two adjacent thermoelectric elements for the top layer using a sacrificial filler material is also demonstrated. A flat 50.8 mm × 50.8 mm TEG module is fabricated using this method and its performance is experimentally characterized and found to be in agreement with expected values of open-circuit voltage based on the materials used.

  1. Food additives

    PubMed Central

    Spencer, Michael

    1974-01-01

    Food additives are discussed from the food technology point of view. The reasons for their use are summarized: (1) to protect food from chemical and microbiological attack; (2) to even out seasonal supplies; (3) to improve their eating quality; (4) to improve their nutritional value. The various types of food additives are considered, e.g. colours, flavours, emulsifiers, bread and flour additives, preservatives, and nutritional additives. The paper concludes with consideration of those circumstances in which the use of additives is (a) justified and (b) unjustified. PMID:4467857

  2. Micromechanical Structures Fabrication

    SciTech Connect

    Rajic, S

    2001-05-08

    Work in materials other than silicon for MEMS applications has typically been restricted to metals and metal oxides instead of more ''exotic'' semiconductors. However, group III-V and II-VI semiconductors form a very important and versatile collection of material and electronic parameters available to the MEMS and MOEMS designer. With these materials, not only are the traditional mechanical material variables (thermal conductivity, thermal expansion, Young's modulus, etc.) available, but also chemical constituents can be varied in ternary and quaternary materials. This flexibility can be extremely important for both friction and chemical compatibility issues for MEMS. In addition, the ability to continually vary the bandgap energy can be particularly useful for many electronics and infrared detection applications. However, there are two major obstacles associated with alternate semiconductor material MEMS. The first issue is the actual fabrication of non-silicon micro-devices and the second impediment is communicating with these novel devices. We have implemented an essentially material independent fabrication method that is amenable to most group III-V and II-VI semiconductors. This technique uses a combination of non-traditional direct write precision fabrication processes such as diamond turning, ion milling, laser ablation, etc. This type of deterministic fabrication approach lends itself to an almost trivial assembly process. We also implemented a mechanical, electrical, and optical self-aligning hybridization technique for these alternate-material MEMS substrates.

  3. Fabrication of multipoint light emitting optical fibers for optogenetics

    NASA Astrophysics Data System (ADS)

    Sileo, Leonardo; Pisanello, Marco; De Vittorio, Massimo; Pisanello, Ferruccio

    2015-03-01

    Multipoint Light Emitting Optical Fibers (MPF) has been recently demonstrated as a versatile tool for spatially addressable optogenetics experiments. Their fabrication has been possible thanks to a number of key microfabrication technologies, in particular the unique nanofabrication capabilities of a Focused Ion Beam. This work provides the complete description of MPF fabrication, detailing the optimization process for each fabrication step.

  4. Fabrication of Pop-up Detector Arrays on Si Wafers

    NASA Technical Reports Server (NTRS)

    Li, Mary J.; Allen, Christine A.; Gordon, Scott A.; Kuhn, Jonathan L.; Mott, David B.; Stahle, Caroline K.; Wang, Liqin L.

    1999-01-01

    High sensitivity is a basic requirement for a new generation of thermal detectors. To meet the requirement, close-packed, two-dimensional silicon detector arrays have been developed in NASA Goddard Space Flight Center. The goal of the task is to fabricate detector arrays configured with thermal detectors such as infrared bolometers and x-ray calorimeters to use in space fliGht missions. This paper focuses on the fabrication and the mechanical testing of detector arrays in a 0.2 mm pixel size, the smallest pop-up detectors being developed so far. These array structures, nicknamed "PUDS" for "Pop-Up Detectors", are fabricated on I pm thick, single-crystal, silicon membranes. Their designs have been refined so we can utilize the flexibility of thin silicon films by actually folding the silicon membranes to 90 degrees in order to obtain close-packed two-dimensional arrays. The PUD elements consist of a detector platform and two legs for mechanical support while also serving as electrical and thermal paths. Torsion bars and cantilevers connecting the detector platform to the legs provide additional flexures for strain relief. Using micro-electromechanical structure (MEMS) fabrication techniques, including photolithography, anisotropic chemical etching, reactive-ion etching, and laser dicing, we have fabricated PLTD detector arrays of fourteen designs with a variation of four parameters including cantilever length, torsion bar length and width, and leg length. Folding tests were conducted to test mechanical stress distribution for the array structures. We obtained folding yields and selected optimum design parameters to reach minimal stress levels. Computer simulation was also employed to verify mechanical behaviors of PUDs in the folding process. In addition, scanning electron microscopy was utilized to examine the flatness of detectors and the alignment of detector pixels in arrays. The fabrication of thermistors and heaters on the pop-up detectors is under way

  5. Stepping motor controller

    DOEpatents

    Bourret, S.C.; Swansen, J.E.

    1982-07-02

    A stepping motor is microprocessor controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  6. Stepping motor controller

    DOEpatents

    Bourret, Steven C.; Swansen, James E.

    1984-01-01

    A stepping motor is microprocessingly controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  7. Step-Growth Polymerization.

    ERIC Educational Resources Information Center

    Stille, J. K.

    1981-01-01

    Following a comparison of chain-growth and step-growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step-growth polymerization kinetics, synthesis and molecular weight distribution of some linear step-growth polymers, and three-dimensional network step-growth polymers. (JN)

  8. Ultra-Low-Background Copper Production and Clean Fabrication

    SciTech Connect

    Aalseth, C.E.; Brodzinski, R.L.; Farmer, O.T.; Hoppe, E.W.; Hossbach, T.W.; Miley, H.S.; Reeves, J.H.

    2005-09-08

    Commercial high-purity copper is an attractive material for constructing ultra-low-background radiation measurement devices. When even higher purity is desired, additional electrolytic and chemical purification can be combined with the final fabrication step. This process results in 'electroformed' copper parts of extreme purity. Copper electroforming can be done underground, providing a way to eliminate cosmogenic activation products seen in copper that has had above-ground exposure. A brief summary of the history, cosmogenics, process chemistry, cleaning, and passivation of this material is given. Examples of finished parts illustrate the method. The required infrastructure is summarized.

  9. Ultra-Low-Background Copper Production and Clean Fabrication

    SciTech Connect

    Aalseth, Craig E.; Brodzinski, Ronald L.; Farmer, O T.; Hoppe, Eric W.; Hossbach, Todd W.; Miley, Harry S.; Reeves, James H.

    2005-11-01

    Commercial high-purity copper is an attractive material for constructing ultra-low-background radiation measurement devices. When even higher purity is desired, additional electrolytic and chemical purification can be combined with the final fabrication step. This process results in ''electroformed'' copper parts of extreme purity. Copper electroforming can be done underground, providing a way to eliminate cosmogenic activation products seen in copper that has had above-ground exposure. A brief summary of the history, cosmogenics, process chemistry, cleaning, and passivation of this material is given. Examples of finished parts illustrate the method. The required infrastructure is summarized.

  10. Perspectives on Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Bourell, David L.

    2016-07-01

    Additive manufacturing (AM) has skyrocketed in visibility commercially and in the public sector. This article describes the development of this field from early layered manufacturing approaches of photosculpture, topography, and material deposition. Certain precursors to modern AM processes are also briefly described. The growth of the field over the last 30 years is presented. Included is the standard delineation of AM technologies into seven broad categories. The economics of AM part generation is considered, and the impacts of the economics on application sectors are described. On the basis of current trends, the future outlook will include a convergence of AM fabricators, mass-produced AM fabricators, enabling of topology optimization designs, and specialization in the AM legal arena. Long-term developments with huge impact are organ printing and volume-based printing.

  11. Scanning Tunneling Spectroscopy Study of Single Layer Step Edges on Si (100) Surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Xiqiao; Namboodiri, Pradeep; Li, Kai; Deng, Xiao; Silver, Richard

    Advanced Hydrogen lithography enables the fabrication of atomically precise donor-based quantum devices on Si(100) surfaces. Understanding the defect and step edge interaction with local electronic and geometric structures is needed to properly interpret device measurement results. Low temperature Si epitaxy, used to encapsulate devices, introduces island growth and step edges near/above buried donor nanostructures, presenting a real challenge in relocating and characterizing buried donor devices using Scanning Tunneling Microscopy/Spectroscopy (STM/STS). We present spatially resolved STS results across single layer steps on Si(100) surfaces. While the electronic properties across SA steps were found to be very similar to that on flat terraces, we observed an edge induced gap state on rebonded SB step edges, which was assigned to the unpaired dangling bond state at the lower edge atom of the rebonded SB steps. In addition, we used computational simulation within Bardeen's formalism to probe the influence of subsurface doping density profiles on the observed STS features over step edges and other defects. This study will help to elucidate the role played by surface step edges and subsurface doping densities in characterizing surface and subsurface nanostructures using STS/STM.

  12. Electrohydrodynamics: A facile technique to fabricate drug delivery systems

    PubMed Central

    Chakraborty, Syandan; Liao, I-Chien; Adler, Andrew; Leong, Kam W.

    2009-01-01

    Electrospinning and electrospraying are facile electrohydrodynamic fabrication methods that can generate drug delivery systems (DDS) through a one-step process. The nano-structured fiber and particle morphologies produced by these techniques offer tunable release kinetics applicable to diverse biomedical applications. Coaxial-electrospinning/electrospraying, a relatively new technique of fabricating core-shell fibers/particles have added to the versatility of these DDS by affording a near zero-order drug release kinetics, dampening of burst release, and applicability to a wider range of bioactive agents. Controllable electrospinning/spraying of fibers and particles and subsequent drug release from these chiefly polymeric vehicles depends on well-defined solution and process parameters. The additional drug delivery capability from electrospun fibers can further enhance the material’s functionality in tissue engineering applications. This review discusses the state-of-the-art of using electrohydrodynamic technique to generate nano-fiber/particles as drug delivery devices. PMID:19651167

  13. Fabric circuits and method of manufacturing fabric circuits

    NASA Technical Reports Server (NTRS)

    Chu, Andrew W. (Inventor); Dobbins, Justin A. (Inventor); Scully, Robert C. (Inventor); Trevino, Robert C. (Inventor); Lin, Greg Y. (Inventor); Fink, Patrick W. (Inventor)

    2011-01-01

    A flexible, fabric-based circuit comprises a non-conductive flexible layer of fabric and a conductive flexible layer of fabric adjacent thereto. A non-conductive thread, an adhesive, and/or other means may be used for attaching the conductive layer to the non-conductive layer. In some embodiments, the layers are attached by a computer-driven embroidery machine at pre-determined portions or locations in accordance with a pre-determined attachment layout before automated cutting. In some other embodiments, an automated milling machine or a computer-driven laser using a pre-designed circuit trace as a template cuts the conductive layer so as to separate an undesired portion of the conductive layer from a desired portion of the conductive layer. Additional layers of conductive fabric may be attached in some embodiments to form a multi-layer construct.

  14. Step by Step: Avoiding Spiritual Bypass in 12-Step Work

    ERIC Educational Resources Information Center

    Cashwell, Craig S.; Clarke, Philip B.; Graves, Elizabeth G.

    2009-01-01

    With spirituality as a cornerstone, 12-step groups serve a vital role in the recovery community. It is important for counselors to be mindful, however, of the potential for clients to be in spiritual bypass, which likely will undermine the recovery process.

  15. Ceramic fabrication R D

    SciTech Connect

    Not Available

    1990-01-01

    This project is separated into three tasks. The first task is a design and modelling effort to be carried out by MSE, Inc. The purpose of this task is to develop and analyze designs for various cohesive ceramic fabrication (CCF) components, principally an MHD electrode for strategic defense initiative (SDI) applications. A high stress, low cost, ceramic component is to be selected, designed and, if possible, analyzed. The final design for the MHD electrode comprised a layered structure of molybdenum disilicide graded with quartz glass. The design demonstrates the fabrication capabilities of the CCF process. The high stress component was targeted at armor applications and will be thick alumina plate. Silicon carbide reinforcement of the alumina will be explored. Task 2 is directed at establishing a mechanical properties data base for monolithic and laminated alumina fabricated using the CCF process. Task 3 involved production of a solid oxide fuel cell model electrode; however, work ceased when it became apparent that successful integration of the electrode modules would require additional time. Currently, work is principally focused on the production of thick CCF alumina plates; three test plates were ballistically tested and showed a very satisfactory performance. Silicon carbide reinforcement of the CCF alumina is being explored. Effort on the CCF processing of molybdenum disilicide (a nonoxide material) continued at a reduced level. Sinter aids were explored, and densities of 87% theoretical density on pressureless sintered dry pressed pellets were achieved. 1 ref., 9 figs., 4 tabs.

  16. Fabrication Capabilities Utilizing In Situ Materials

    NASA Technical Reports Server (NTRS)

    McLemore, Carole A.; Fikes, John C.; Darby, Charles A.; Good, James E.; Gilley, Scott D.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) has a Space Exploration Policy that lays out a plan that far exceeds the earlier Apollo goals where landing on the moon and taking those first historic steps fulfilled the mission. The policy states that we will set roots on the moon by establishing an outpost. This outpost will be used as a test bed for residing in more distant locales, such as Mars. In order to become self-sufficient, the occupants must have the capability to fabricate component parts in situ. Additionally, in situ materials must be used to minimize valuable mission upmass and to be as efficient as possible. In situ materials can be found from various sources such as raw lunar regolith whereby specific constituents can be extracted from the regolith (such as aluminum, titanium, or iron), and existing hardware already residing on the moon from past Apollo missions. The Electron Beam Melting (EBM) process lends itself well to fabricating parts, tools, and other necessary items using in situ materials and will be discussed further in this paper.

  17. Additive manufacturing of ceramic structures by laser engineered net shaping

    NASA Astrophysics Data System (ADS)

    Niu, Fangyong; Wu, Dongjiang; Ma, Guangyi; Zhang, Bi

    2015-11-01

    Ceramic is an important material with outstanding physical properties whereas impurities and porosities generated by traditional manufacturing methods limits its further industrial applications. In order to solve this problem, direct fabrication of Al2O3 ceramic structures is conducted by laser engineered net shaping system and pure ceramic powders. Grain refinement strengthening method by doping ZrO2 and dispersion strengthening method by doping SiC are proposed to suppress cracks in fabricating Al2O3 structure. Phase compositions, microstructures as well as mechanical properties of fabricated specimens are then analyzed. The results show that the proposed two methods are effective in suppressing cracks and structures of single-bead wall, arc and cylinder ring are successfully deposited. Stable phase of α-Al2O3 and t-ZrO2 are obtained in the fabricated specimens. Micro-hardness higher than 1700 HV are also achieved for both Al2O3 and Al2O3/ZrO2, which are resulted from fine directional crystals generated by the melting-solidification process. Results presented indicate that additive manufacturing is a very attractive technique for the production of high-performance ceramic structures in a single step.

  18. Phosphazene additives

    DOEpatents

    Harrup, Mason K; Rollins, Harry W

    2013-11-26

    An additive comprising a phosphazene compound that has at least two reactive functional groups and at least one capping functional group bonded to phosphorus atoms of the phosphazene compound. One of the at least two reactive functional groups is configured to react with cellulose and the other of the at least two reactive functional groups is configured to react with a resin, such as an amine resin of a polycarboxylic acid resin. The at least one capping functional group is selected from the group consisting of a short chain ether group, an alkoxy group, or an aryloxy group. Also disclosed are an additive-resin admixture, a method of treating a wood product, and a wood product.

  19. Potlining Additives

    SciTech Connect

    Rudolf Keller

    2004-08-10

    In this project, a concept to improve the performance of aluminum production cells by introducing potlining additives was examined and tested. Boron oxide was added to cathode blocks, and titanium was dissolved in the metal pool; this resulted in the formation of titanium diboride and caused the molten aluminum to wet the carbonaceous cathode surface. Such wetting reportedly leads to operational improvements and extended cell life. In addition, boron oxide suppresses cyanide formation. This final report presents and discusses the results of this project. Substantial economic benefits for the practical implementation of the technology are projected, especially for modern cells with graphitized blocks. For example, with an energy savings of about 5% and an increase in pot life from 1500 to 2500 days, a cost savings of $ 0.023 per pound of aluminum produced is projected for a 200 kA pot.

  20. Improvements in Cold-Plate Fabrication

    NASA Technical Reports Server (NTRS)

    Zaffetti, Mark A.; Taddey, Edmund P.; Laurin, Michael B.; Chabebe, Natalia

    2012-01-01

    Five improvements are reported in cold-plate fabrication. This cold plate is part of a thermal control system designed to serve on space missions. The first improvement is the merging of the end sheets of the cold plate with the face sheets of the structural honeycomb panel. The cold plate, which can be a brazed assembly, uses the honeycomb face sheet as its end sheet. Thus, when the honeycomb panel is fabricated, the face sheet that is used is already part of the cold plate. In addition to reducing weight, costs, and steps, the main benefit of this invention is that it creates a more structurally sound assembly. The second improvement involves incorporation of the header into the closure bar to pass the fluid to a lower layer. Conventional designs have used a separate header, which increases the geometry of the system. The improvement reduces the geometry, thus allowing the cold plate to fit into smaller area. The third improvement eliminates the need of hose, tube, or manifold to supply the cooling fluid externally. The external arrangement can be easily damaged and is vulnerable to leakage. The new arrangement incorporates an internal fluid transfer tube. This allows the fluid to pass from one cold plate to the other without any exposed external features. The fourth improvement eliminates separate fabrication of cold plate(s) and structural members followed by a process of attaching them to each other. Here, the structural member is made of material that can be brazed just as that of the cold plate. Now the structural member and the cold plate can be brazed at the same time, creating a monolithic unit, and thus a more structurally sound assembly. Finally, the fifth improvement is the elimination of an additional welding step that can damage the braze joints. A tube section, which is usually welded on after the braze process, is replaced with a more structurally sound configuration that can be brazed at the same time as the rest of the cold plate.

  1. Fabrication of Uranium Oxycarbide Kernels for HTR Fuel

    SciTech Connect

    Charles Barnes; CLay Richardson; Scott Nagley; John Hunn; Eric Shaber

    2010-10-01

    Babcock and Wilcox (B&W) has been producing high quality uranium oxycarbide (UCO) kernels for Advanced Gas Reactor (AGR) fuel tests at the Idaho National Laboratory. In 2005, 350-µm, 19.7% 235U-enriched UCO kernels were produced for the AGR-1 test fuel. Following coating of these kernels and forming the coated-particles into compacts, this fuel was irradiated in the Advanced Test Reactor (ATR) from December 2006 until November 2009. B&W produced 425-µm, 14% enriched UCO kernels in 2008, and these kernels were used to produce fuel for the AGR-2 experiment that was inserted in ATR in 2010. B&W also produced 500-µm, 9.6% enriched UO2 kernels for the AGR-2 experiments. Kernels of the same size and enrichment as AGR-1 were also produced for the AGR-3/4 experiment. In addition to fabricating enriched UCO and UO2 kernels, B&W has produced more than 100 kg of natural uranium UCO kernels which are being used in coating development tests. Successive lots of kernels have demonstrated consistent high quality and also allowed for fabrication process improvements. Improvements in kernel forming were made subsequent to AGR-1 kernel production. Following fabrication of AGR-2 kernels, incremental increases in sintering furnace charge size have been demonstrated. Recently small scale sintering tests using a small development furnace equipped with a residual gas analyzer (RGA) has increased understanding of how kernel sintering parameters affect sintered kernel properties. The steps taken to increase throughput and process knowledge have reduced kernel production costs. Studies have been performed of additional modifications toward the goal of increasing capacity of the current fabrication line to use for production of first core fuel for the Next Generation Nuclear Plant (NGNP) and providing a basis for the design of a full scale fuel fabrication facility.

  2. Microfluidic fabrication of asymmetric giant lipid vesicles

    PubMed Central

    Hu, Peichi C.; Li, Su; Malmstadt, Noah

    2011-01-01

    We have developed a microfluidic technology for the fabrication of compositionally asymmetric giant unilamellar vesicles (GUVs). The vesicles are assembled in two independent steps. In each step, a lipid monolayer is formed at a water-oil interface. The first monolayer is formed inside of a microfluidic device with a multiphase droplet flow configuration consisting of a continuous oil stream in which water droplets are formed. These droplets are dispensed into a vessel containing a layer of oil over a layer of water. The second lipid monolayer is formed by transferring the droplets through this second oil-water interface by centrifugation. By dissolving different lipid compositions in the different oil phases, the composition of each leaflet of the resulting lipid bilayer can be controlled. We have demonstrated membrane asymmetry by showing differential fluorescence quenching of labeled lipids in each leaflet and by demonstrating that asymmetric GUVs will bind an avidin-coated surface only when biotinylated lipids are targeted to the outer leaflet. In addition, we have demonstrated the successful asymmetric targeting of phosphatidylserine lipids to each leaflet, producing membranes with a biomimetic and physiologically relevant compositional asymmetry. PMID:21449588

  3. A novel method of microneedle array fabrication using inclined deep x-ray exposure

    NASA Astrophysics Data System (ADS)

    Moon, Sang Jun; Jin, Chun Yan; Lee, Seung S.

    2006-04-01

    We report a novel fabrication method for the microneedle array with a 3-dimentional feature and its replication method; ''Hot-pressing'' process with bio-compatible material, PLLA (Poly L-LActide). Using inclined deep X-ray exposure technique, we fabricate a band type microneedle array with a single body on the same material basement. Since the single body feature does not make adhesion problem with the microneedle shank and basement during peel-off step of a mold, the PMMA (Poly-Methyl-MethAcrylate) microneedle array mold insert can be used for mold process which is used with the soft material mold, PDMS (Poly-Di- Methyl-Siloxane). The side inclined deep X-ray exposure also makes complex 3-dimentional features by the regions which are not exposed during twice successive exposure steps. In addition, the successive exposure does not need an additional mask alignment after the first side exposure. The fabricated band type microneedle array mold inserts are assembled for large area patch type out-of-plane microneedle array. The bio-compatible microneedle array can be fabricated to the laboratory scale mass production by the single body PMMA mold insert and ''Hot-pressing'' process.

  4. Polymorphous computing fabric

    DOEpatents

    Wolinski, Christophe Czeslaw; Gokhale, Maya B.; McCabe, Kevin Peter

    2011-01-18

    Fabric-based computing systems and methods are disclosed. A fabric-based computing system can include a polymorphous computing fabric that can be customized on a per application basis and a host processor in communication with said polymorphous computing fabric. The polymorphous computing fabric includes a cellular architecture that can be highly parameterized to enable a customized synthesis of fabric instances for a variety of enhanced application performances thereof. A global memory concept can also be included that provides the host processor random access to all variables and instructions associated with the polymorphous computing fabric.

  5. Cyclic steps on ice

    NASA Astrophysics Data System (ADS)

    Yokokawa, M.; Izumi, N.; Naito, K.; Parker, G.; Yamada, T.; Greve, R.

    2016-05-01

    Boundary waves often form at the interface between ice and fluid flowing adjacent to it, such as ripples under river ice covers, and steps on the bed of supraglacial meltwater channels. They may also be formed by wind, such as the megadunes on the Antarctic ice sheet. Spiral troughs on the polar ice caps of Mars have been interpreted to be cyclic steps formed by katabatic wind blowing over ice. Cyclic steps are relatives of upstream-migrating antidunes. Cyclic step formation on ice is not only a mechanical but also a thermodynamic process. There have been very few studies on the formation of either cyclic steps or upstream-migrating antidunes on ice. In this study, we performed flume experiments to reproduce cyclic steps on ice by flowing water, and found that trains of steps form when the Froude number is larger than unity. The features of those steps allow them to be identified as ice-bed analogs of cyclic steps in alluvial and bedrock rivers. We performed a linear stability analysis and obtained a physical explanation of the formation of upstream-migrating antidunes, i.e., precursors of cyclic steps. We compared the results of experiments with the predictions of the analysis and found the observed steps fall in the range where the analysis predicts interfacial instability. We also found that short antidune-like undulations formed as a precursor to the appearance of well-defined steps. This fact suggests that such antidune-like undulations correspond to the instability predicted by the analysis and are precursors of cyclic steps.

  6. A simple solution-immersion process for the fabrication of superhydrophobic cupric stearate surface with easy repairable property

    NASA Astrophysics Data System (ADS)

    Li, Jian; Liu, Xiaohong; Ye, Yinping; Zhou, Huidi; Chen, Jianmin

    2011-12-01

    The present work reports a simple and time-saving method to fabricate cupric stearate film on zinc substrate by a solution-immersion process. Superhydrophobic surfaces are conventionally prepared employing two steps: roughening a surface and lowering its surface energy. The fabrication of superhydrophobic cupric stearate surface is reported using a one-step process by immersing a zinc plate coated with copper into the stearic acid solution, simplifying the complexity of two different steps involved in the conventional methods. The surface of the zinc plate coated with copper is found to be covered with low surface energy cupric stearate film providing the water contact angle of 160 ± 1° with the rolling off properties. In addition, the damaged superhydrophobic surface can restore superhydrophobicity property by immersing the surface into the stearic acid solution again.

  7. Vinyl capped addition polyimides

    NASA Technical Reports Server (NTRS)

    Vannucci, Raymond D. (Inventor); Malarik, Diane C. (Inventor); Delvigs, Peter (Inventor)

    1991-01-01

    Polyimide resins (PMR) are generally useful where high strength and temperature capabilities are required (at temperatures up to about 700 F). Polyimide resins are particularly useful in applications such as jet engine compressor components, for example, blades, vanes, air seals, air splitters, and engine casing parts. Aromatic vinyl capped addition polyimides are obtained by reacting a diamine, an ester of tetracarboxylic acid, and an aromatic vinyl compound. Low void materials with improved oxidative stability when exposed to 700 F air may be fabricated as fiber reinforced high molecular weight capped polyimide composites. The aromatic vinyl capped polyimides are provided with a more aromatic nature and are more thermally stable than highly aliphatic, norbornenyl-type end-capped polyimides employed in PMR resins. The substitution of aromatic vinyl end-caps for norbornenyl end-caps in addition polyimides results in polymers with improved oxidative stability.

  8. A new and economic approach to synthesize and fabricate bioactive diopside ceramics using a modified domestic microwave oven. Part 2: effect of P2O5 additions on diopside bioactivity and mechanical properties.

    PubMed

    Zouai, Souheila; Harabi, Abdelhamid; Karboua, Noureddine; Harabi, Esma; Chehlatt, Sihem; Barama, Salah-Edine; Zaiou, Soumia; Bouzerara, Ferhat; Guerfa, Fatiha

    2016-04-01

    In this work, diopside based ceramics was obtained by solid state reaction using conventional sintering (CS) and microwave sintering (MS). Moreover, different amounts of P2O5 (0.5-5.0 wt.%) have been added. It has been found that a relative density up to 95% theoretical was obtained for diopside containing 2.0 and 5.0 wt.% P2O5, sintered at 1250 °C for 2h and at 1075 °C only for 15 min using CS and MS. Excellent values of micro hardness (7.4 ± 0.1 GPa) and 3 point flexural strength (about 270 MPa) for samples containing 5 wt.% P2O5, sintered at 1075 °C for 15 min using MS were measured. Besides this, a relatively low weight loss ratio has been measured (0.01%) for diopside samples containing 5 wt.% P2O5, sintered under the same conditions, after soaking in physiological salt solution for 2 days. Additionally, the bioactivity of diopside by the possibility of formation of apatite on the surface of pure diopside and diopside containing 2 wt.% of P2O5 immersed in simulated body fluid (SBF) was also confirmed. Finally, particular nano-sized of Carbonated hydroxyapatite (CHA) crystals (rice shaped) were formed and covered the surface of these samples, soaked in SBF solution for 14 days.

  9. A new and economic approach to synthesize and fabricate bioactive diopside ceramics using a modified domestic microwave oven. Part 2: effect of P2O5 additions on diopside bioactivity and mechanical properties.

    PubMed

    Zouai, Souheila; Harabi, Abdelhamid; Karboua, Noureddine; Harabi, Esma; Chehlatt, Sihem; Barama, Salah-Edine; Zaiou, Soumia; Bouzerara, Ferhat; Guerfa, Fatiha

    2016-04-01

    In this work, diopside based ceramics was obtained by solid state reaction using conventional sintering (CS) and microwave sintering (MS). Moreover, different amounts of P2O5 (0.5-5.0 wt.%) have been added. It has been found that a relative density up to 95% theoretical was obtained for diopside containing 2.0 and 5.0 wt.% P2O5, sintered at 1250 °C for 2h and at 1075 °C only for 15 min using CS and MS. Excellent values of micro hardness (7.4 ± 0.1 GPa) and 3 point flexural strength (about 270 MPa) for samples containing 5 wt.% P2O5, sintered at 1075 °C for 15 min using MS were measured. Besides this, a relatively low weight loss ratio has been measured (0.01%) for diopside samples containing 5 wt.% P2O5, sintered under the same conditions, after soaking in physiological salt solution for 2 days. Additionally, the bioactivity of diopside by the possibility of formation of apatite on the surface of pure diopside and diopside containing 2 wt.% of P2O5 immersed in simulated body fluid (SBF) was also confirmed. Finally, particular nano-sized of Carbonated hydroxyapatite (CHA) crystals (rice shaped) were formed and covered the surface of these samples, soaked in SBF solution for 14 days. PMID:26838883

  10. Fabrication and Test Results of a Prototype, Nb3Sn Superconducting Racetrack Dipole Magnet

    SciTech Connect

    Gourlay, S. A.; Chow, K.; Dietderich, D.R.; Gupta, R.; Hannaford, R.; Harnden, W.; Lietzke, A.; McInturff, A.D.; Millos, G.A.; Morrison, L.; Morrison, M.; Scanlan, R.M.

    1998-09-01

    A prototype, Nb{sub 3}Sn superconducting magnet, utilizing a racetrack coil design has been built and tested. This magnet represents the first step in a recently implemented program to develop a high field, accelerator quality magnet. This magnet was constructed with coils wound from conductor developed for the ITER project, limiting the magnet to a field of 6-7 Tesla. Subsequent magnets in the program will utilize improved conductor, culminating in a magnet design capable of producing fields approaching 15 Tesla. The simple geometry is more suitable for the use of brittle superconductors necessary to eventually reach high field levels. In addition, fewer and simpler parts are used in fabricating these coils compared with the more conventional cosine theta cross section coils. The general fabrication steps, mechanical design and quench performance are discussed.

  11. Silicon-solar-cell process development, fabrication, and analysis. Final report

    SciTech Connect

    Minahan, J.A.

    1981-03-09

    Solar cells have been fabricated from unconventional silicon materials in the second and final phase of the contract. In the most recent period of work, EFG, Web, Hem, and Continuous CZ silicon materials were fabricated into solar cells, measured and analyzed. Current-voltage measurements under AM1 conditions, in addition to those under AMO conditions, were introduced in Phase II. Several low-cost fabrication steps were included in that phase. Both Hem and Continuous CZ silicon were found to be superior to what had been provided in Phase I. Correlation between quality of starting materials and cell conversion efficiency was observed for Hem-grown silicon. Correlation between position in the crystal growth sequence and cell quality was observed for Continuous CZ.

  12. Golgi-Cox Staining Step by Step

    PubMed Central

    Zaqout, Sami; Kaindl, Angela M.

    2016-01-01

    Golgi staining remains a key method to study neuronal morphology in vivo. Since most protocols delineating modifications of the original staining method lack details on critical steps, establishing this method in a laboratory can be time-consuming and frustrating. Here, we describe the Golgi-Cox staining in such detail that should turn the staining into an easily feasible method for all scientists working in the neuroscience field. PMID:27065817

  13. Improved flexibility with grayscale fabrication of calcium fluoride homogenizers

    NASA Astrophysics Data System (ADS)

    Brown, Jeremiah; Brakhage, Peter; Simmons, Lamarr; Mueller, Ralf

    2012-03-01

    High quality and highly uniform illumination is a critical component for advanced lithography systems and wafer inspection tools. Homogenizer elements fabricated in calcium fluoride have demonstrated good performance for deep UV applications. Grayscale photolithography allows for the fabrication of single-sided micro lens array (MLA) elements with excellent optical performance. The MLA offers some significant advantages over crossed cylinders fabricated using grayscale photolithography processes, including the reduction in the number of fabrication steps and the added flexibility of manufacturing noncylindrical surface geometries. This research presentation reviews the fabrication process and compares grayscale crossed cylindrical arrays and MLAs in terms of their capabilities and performance.

  14. STEP Experiment Requirements

    NASA Technical Reports Server (NTRS)

    Brumfield, M. L. (Compiler)

    1984-01-01

    A plan to develop a space technology experiments platform (STEP) was examined. NASA Langley Research Center held a STEP Experiment Requirements Workshop on June 29 and 30 and July 1, 1983, at which experiment proposers were invited to present more detailed information on their experiment concept and requirements. A feasibility and preliminary definition study was conducted and the preliminary definition of STEP capabilities and experiment concepts and expected requirements for support services are presented. The preliminary definition of STEP capabilities based on detailed review of potential experiment requirements is investigated. Topics discussed include: Shuttle on-orbit dynamics; effects of the space environment on damping materials; erectable beam experiment; technology for development of very large solar array deployers; thermal energy management process experiment; photovoltaic concentrater pointing dynamics and plasma interactions; vibration isolation technology; flight tests of a synthetic aperture radar antenna with use of STEP.

  15. Phenylethynyl Containing Reactive Additives

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2002-01-01

    Phenylethynyl containing reactive additives were prepared from aromatic diamine, containing phenylethvnvl groups and various ratios of phthalic anhydride and 4-phenylethynviphthalic anhydride in glacial acetic acid to form the imide in one step or in N-methyl-2-pvrrolidinone to form the amide acid intermediate. The reactive additives were mixed in various amounts (10% to 90%) with oligomers containing either terminal or pendent phenylethynyl groups (or both) to reduce the melt viscosity and thereby enhance processability. Upon thermal cure, the additives react and become chemically incorporated into the matrix and effect an increase in crosslink density relative to that of the host resin. This resultant increase in crosslink density has advantageous consequences on the cured resin properties such as higher glass transition temperature and higher modulus as compared to that of the host resin.

  16. Color Addition and Subtraction Apps

    ERIC Educational Resources Information Center

    Ruiz, Frances; Ruiz, Michael J.

    2015-01-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step…

  17. Color Addition and Subtraction Apps

    NASA Astrophysics Data System (ADS)

    Ruiz, Frances; Ruiz, Michael J.

    2015-10-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step in understanding mathematical representations of RGB color. Finally, color addition and subtraction are presented for the X11 colors from web design to illustrate yet another real-life application of color mixing.

  18. Planar intrinsic Josephson junctions fabricated on Bi-2212 LPE films

    NASA Astrophysics Data System (ADS)

    Yasuda, Takashi; Kawae, Takeshi; Yamashita, Tsutomu; Taka, Chihiro; Nishida, Akihiko; Takano, Shuzo

    2003-05-01

    Planar design of intrinsic Josephson junctions (IJJs) is studied using Bi2Sr2CaCu2Ox (Bi-2212) films prepared by liquid phase epitaxy. Step-type IJJ stacks fabricated on step-patterned MgO substrates exhibit multibranched current-voltage characteristics inherent in Bi-2212 single crystals. This behavior is found to be limited to films on small-angle steps, suggesting the incorporation of defects near the steep steps of substrates.

  19. Apparatus and process for freeform fabrication of composite reinforcement preforms

    NASA Technical Reports Server (NTRS)

    Yang, Junsheng (Inventor); Wu, Liangwei (Inventor); Liu, Junhai (Inventor); Jang, Bor Z. (Inventor)

    2001-01-01

    A solid freeform fabrication process and apparatus for making a three-dimensional reinforcement shape. The process comprises the steps of (1) operating a multiple-channel material deposition device for dispensing a liquid adhesive composition and selected reinforcement materials at predetermined proportions onto a work surface; (2) during the material deposition process, moving the deposition device and the work surface relative to each other in an X-Y plane defined by first and second directions and in a Z direction orthogonal to the X-Y plane so that the materials are deposited to form a first layer of the shape; (3) repeating these steps to deposit multiple layers for forming a three-dimensional preform shape; and (4) periodically hardening the adhesive to rigidize individual layers of the preform. These steps are preferably executed under the control of a computer system by taking additional steps of (5) creating a geometry of the shape on the computer with the geometry including a plurality of segments defining the preform shape and each segment being preferably coded with a reinforcement composition defining a specific proportion of different reinforcement materials; (6) generating programmed signals corresponding to each of the segments in a predetermined sequence; and (7) moving the deposition device and the work surface relative to each other in response to these programmed signals. Preferably, the system is also operated to generate a support structure for any un-supported feature of the 3-D preform shape.

  20. Bonding Heat-Resistant Fabric to Tile

    NASA Technical Reports Server (NTRS)

    Holt, J. W.; Smiser, L. W.

    1985-01-01

    Acid etching, densification, and silica cement ensure strong bond. Key step in preparation for bonding to glazed tile is etching quartz fabric and tile with acid. This increases adhesion of silica cement used to form bond. Procedures use high-temperature materials exclusively and therefore suitable for securing flexible seals and heat barriers around doors and viewing ports in furnaces and kilns.

  1. Micro-fabrication Techniques for Target Components

    SciTech Connect

    Miles, R; Hamilton, J; Crawford, J; Ratti, S; Trevino, J; Graff, T; Stockton, C; Harvey, C

    2008-06-10

    Micro-fabrication techniques, derived from the semi-conductor industry, can be used to make a variety of useful mechanical components for targets. A selection of these components including supporting cooling arms for prototype cryogenic inertial confinement fusion targets, stepped and graded density targets for materials dynamics experiments are described. Micro-fabrication enables cost-effective, simultaneous fabrication of multiple high-precision components with complex geometries. Micro-fabrication techniques such as thin-film deposition, photo-lithographic patterning and etch processes normally used in the semi-conductor manufacture industry, can be exploited to make useful mechanical target components. Micro-fabrication processes have in recent years been used to create a number of micro-electro-mechanical systems (MEMS) components such as pressure sensors, accelerometers, ink jet printer heads, microfluidics platforms and the like. These techniques consist primarily of deposition of thin films of material, photo-lithographic patterning and etching processes performed sequentially to produce three dimensional structures using essentially planar processes. While the planar technology can be limiting in terms of the possible geometries of the final product, advantages of using these techniques include the ability to make multiple complex structures simultaneously and cost-effectively. Target components fabricated using these techniques include the supporting cooling arms for cryogenic prototype fusion ignition targets, stepped targets for equation-of-state experiments, and graded density reservoirs for material strength experiments.

  2. Technical Seminar: Electron Beam Forming Fabrication

    NASA Video Gallery

    EBF³ uses a focused electron beam in a vacuum environment to create a molten pool on a metallic substrate. This layer-additive process enables fabrication of parts directly from CAD drawings. The ...

  3. The fabrication of 3-D nanostructures by a low- voltage EBL

    NASA Astrophysics Data System (ADS)

    Oh, Seung Hun; Kim, Jae Gu; Kim, Chang Seok; Choi, Doo Sun; Chang, Sunghwan; Jeong, Myung Yung

    2011-02-01

    Three-dimensional (3-D) structures are used in many applications, including the fabrication of opto-electronic and bio-MEMS devices. Among the various fabrication techniques available for 3-D structures, nano imprint lithography (NIL) is preferred for producing nanoscale 3-D patterns because of its simplicity, relatively short processing time, and high manufacturing precision. For efficient replication in NIL, a precise 3-D stamp must be used as an imprinting tool. Hence, we attempted the fabrication of original 3-D master molds by low-voltage electron beam lithography (EBL). We then fabricated polydimethylsiloxane (PDMS) stamps from the original 3-D mold via replica molding with ultrasonic vibration.First, we experimentally analyzed the characteristics of low-voltage EBL in terms of various parameters such as resist thickness, acceleration voltage, aperture size, and baking temperature. From these e-beam exposure experiments, we found that the exposure depth and width were almost saturated at 3 kV or lesser, even when the electron dosage was increased. This allowed for the fabrication of various stepped 3-D nanostructures at a low voltage. In addition, by using line-dose EBL, V-groove patterns could be fabricated on a cured electron resist (ER) at a low voltage and low baking temperature. Finally, the depth variation could be controlled to within 10 nm through superposition exposure at 1 kV. From these results, we determined the optimum electron beam exposure conditions for the fabrication of various 3-D structures on ERs by low-voltage EBL. We then fabricated PDMS stamps via the replica molding process.

  4. 2-Step IMAT and 2-Step IMRT in three dimensions

    SciTech Connect

    Bratengeier, Klaus

    2005-12-15

    In two dimensions, 2-Step Intensity Modulated Arc Therapy (2-Step IMAT) and 2-Step Intensity Modulated Radiation Therapy (IMRT) were shown to be powerful methods for the optimization of plans with organs at risk (OAR) (partially) surrounded by a target volume (PTV). In three dimensions, some additional boundary conditions have to be considered to establish 2-Step IMAT as an optimization method. A further aim was to create rules for ad hoc adaptations of an IMRT plan to a daily changing PTV-OAR constellation. As a test model, a cylindrically symmetric PTV-OAR combination was used. The centrally placed OAR can adapt arbitrary diameters with different gap widths toward the PTV. Along the rotation axis the OAR diameter can vary, the OAR can even vanish at some axis positions, leaving a circular PTV. The width and weight of the second segment were the free parameters to optimize. The objective function f to minimize was the root of the integral of the squared difference of the dose in the target volume and a reference dose. For the problem, two local minima exist. Therefore, as a secondary criteria, the magnitude of hot and cold spots were taken into account. As a result, the solution with a larger segment width was recommended. From plane to plane for varying radii of PTV and OAR and for different gaps between them, different sets of weights and widths were optimal. Because only one weight for one segment shall be used for all planes (respectively leaf pairs), a strategy for complex three-dimensional (3-D) cases was established to choose a global weight. In a second step, a suitable segment width was chosen, minimizing f for this global weight. The concept was demonstrated in a planning study for a cylindrically symmetric example with a large range of different radii of an OAR along the patient axis. The method is discussed for some classes of tumor/organ at risk combinations. Noncylindrically symmetric cases were treated exemplarily. The product of width and weight of

  5. Processes of particle deposition in membrane operation and fabrication.

    PubMed

    Wiesner, M R; Tarabara, V; Cortalezzi, M

    2005-01-01

    The processes that control particle deposition on surfaces that are of interest in understanding operational aspects of membrane filtration, also hold significance in controlling the morphology of particle deposits as intermediate steps in membrane fabrication. This paper summarizes processes controlling particle deposit morphology. The implications of these processes for understanding membrane fouling by particles and in fabricating membranes are then considered.

  6. Processes of particle deposition in membrane operation and fabrication.

    PubMed

    Wiesner, M R; Tarabara, V; Cortalezzi, M

    2005-01-01

    The processes that control particle deposition on surfaces that are of interest in understanding operational aspects of membrane filtration, also hold significance in controlling the morphology of particle deposits as intermediate steps in membrane fabrication. This paper summarizes processes controlling particle deposit morphology. The implications of these processes for understanding membrane fouling by particles and in fabricating membranes are then considered. PMID:16003995

  7. The Next Giant Step

    NASA Video Gallery

    Artist Robert McCall painted "The Next Giant Step" in 1979 to commemorate the heroism and courage of spaceflight pioneers. Located in the lobby of Johnson's building 2, the mural depicts America's ...

  8. A big first step.

    PubMed

    Jones, Howard W

    2004-11-01

    The singleton, term gestation, live birth rate per cycle initiated (BESST) endpoint proposed at the beginning of 2004 is a first big step which should be added to by the consideration of multiple pregnancy rates in relation to singleton rates, by recording of fetal reductions and of pregnancies resulting from cryopreserved material. After three or more steps we may have an accurate reporting system which helps patients to distinguish the pros and cons for singleton term delivery. PMID:15479704

  9. Fabrication of a resin appliance with alloy components using digital technology without an analog impression.

    PubMed

    Al Mortadi, Noor; Jones, Quentin; Eggbeer, Dominic; Lewis, Jeffrey; Williams, Robert J

    2015-11-01

    The aim of this study was to fabricate a resin appliance incorporating "wire" components without the use of an analog impression and dental casts using an intraoral scanner and computer technology to build the appliance. This unique alignment of technology offers an enormous reduction in the number of fabrication steps when compared with more traditional methods of manufacture. The prototype incorporated 2 Adams clasps and a fitted labial bow. The alloy components were built from cobalt-chromium in an initial powdered form using established digital technology methods and then inserted into a build of a resin base plate. This article reports the first known use of computer-aided design and additive manufacture to fabricate a resin and alloy appliance, and constitutes proof of the concept for such manufacturing. The original workflow described could be seen as an example for many other similar appliances, perhaps with active components. The scan data were imported into an appropriate specialized computer-aided design software, which was used in conjunction with a force feedback (haptic) interface. The appliance designs were then exported as stereolithography files and transferred to an additive manufacturing machine for fabrication. The results showed that the applied techniques may provide new manufacturing and design opportunities in orthodontics and highlights the need for intraoral-specific additive manufacture materials to be produced and tested for biocompatibility compliance. In a trial, the retainer was fitted orally and judged acceptable by the clinician according to the typical criteria when placing such appliances in situ. PMID:26522047

  10. Rapid fabrication of materials using directed light fabrication

    SciTech Connect

    Thoma, D.J.; Lewis, G.K.; Milewski, J.O.; Chen, K.C.; Nemec, R.B.

    1997-10-01

    Directed light fabrication (DLF) is a rapid fabrication process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, near-net shape, 3-dimensional metal components from a computer generated solid model. Computer controls dictate the metal deposition pathways, and no preforms or molds are required to generate complex sample geometries. The focal zone of the laser beam is programmed to move along or across a part cross-section, and coupled with a multi-axis sample stage, produces the desired part. By maintaining a constant molten puddle within the focal zone, a continuous liquid/solid interface is possible while achieving constant cooling rates that can be varied between 10 to 10{sup 4} K s{sup -1} and solidification growth rates (that scale with the beam velocity) ranging up to 10{sup 2} m s{sup -1}. The DLF technique offers unique advantages over conventional thermomechanical processes in that many labor and equipment intensive steps can be avoided. Moreover, owing to the flexibility in power distributions of lasers, a variety of materials can be processed, ranging from aluminum alloys to rhenium, and including intermetallics such as Mo{sub 5}Si{sub 3}. As a result, the rapid fabrication of conventional and advanced materials are possible.

  11. Photochemical cutting of fabrics

    DOEpatents

    Piltch, Martin S.

    1994-01-01

    Apparatus for the cutting of garment patterns from one or more layers of fabric. A laser capable of producing laser light at an ultraviolet wavelength is utilized to shine light through a pattern, such as a holographic phase filter, and through a lens onto the one or more layers of fabric. The ultraviolet laser light causes rapid photochemical decomposition of the one or more layers of fabric, but only along the pattern. The balance of the fabric of the one or more layers of fabric is undamaged.

  12. Supercapacitors based on carbon nanotube fuzzy fabric structural composites

    NASA Astrophysics Data System (ADS)

    Alresheedi, Bakheet Awad

    Supercapacitors used in conjunction with batteries offer a solution to energy storage and delivery problems in systems where high power output is required, such as in fully electric cars. This project aimed to enhance current supercapacitor technology by fabricating activated carbon on a substrate consisting of carbon nanotubes (CNTs) grown on a carbon fiber fabric (fuzzy fabric). The fuzzy surface of CNTs lowers electrical resistance and increases porosity, resulting in a flexible fabric with high specific capacitance. Experimental results confirm that the capacitance of activated carbon fabricated on the fuzzy fiber composite is significantly higher than when activated carbon is formed simply on a bare carbon fiber substrate, indicating the usefulness of CNTs in supercapacitor technology. The fabrication of the fuzzy fiber based carbon electrode was fairly complex. The processing steps included composite curing, stabilization, carbonization and activation. Ratios of the three basic ingredients for the supercapacitor (fiber, CNT and polymer matrix) were investigated through experimentation and Grey relational analysis. The aim of Grey relational analysis was to examine factors that affect the overall performance of the supercapacitor. It is based on finding relationships in both independent and interrelated data series (parameters). Using this approach, it was determined that the amount of CNTs on the fiber surface plays a major role in the capacitor properties. An increased amount of CNTs increases the surface area and electrical conductivity of the substrate, while also reducing the required time of activation. Technical advances in the field of Materials and Structures are usually focused on attaining superior performance while reducing weight and cost. To achieve such combinations, multi-functionality has become essential; namely, to reduce weight by imparting additional functions simultaneously to a single material. In this study, a structural composite with

  13. Contact formation and gettering of precipitated impurities by multiple firing during semiconductor device fabrication

    DOEpatents

    Sopori, Bhushan

    2014-05-27

    Methods for contact formation and gettering of precipitated impurities by multiple firing during semiconductor device fabrication are provided. In one embodiment, a method for fabricating an electrical semiconductor device comprises: a first step that includes gettering of impurities from a semiconductor wafer and forming a backsurface field; and a second step that includes forming a front contact for the semiconductor wafer, wherein the second step is performed after completion of the first step.

  14. Closeout of JOYO-1 Specimen Fabrication Efforts

    SciTech Connect

    ME Petrichek; JL Bump; RF Luther

    2005-10-31

    Fabrication was well under way for the JOYO biaxial creep and tensile specimens when the NR Space program was canceled. Tubes of FS-85, ASTAR-811C, and T-111 for biaxial creep specimens had been drawn at True Tube (Paso Robles, CA), while tubes of Mo-47.5 Re were being drawn at Rhenium Alloys (Cleveland, OH). The Mo-47.5 Re tubes are now approximately 95% complete. Their fabrication and the quantities produced will be documented at a later date. End cap material for FS-85, ASTAR-811C, and T-111 had been swaged at Pittsburgh Materials Technology, Inc. (PMTI) (Large, PA) and machined at Vangura (Clairton, PA). Cutting of tubes, pickling, annealing, and laser engraving were in process at PMTI. Several biaxial creep specimen sets of FS-85, ASTAR-811C, and T-111 had already been sent to Pacific Northwest National Laboratory (PNNL) for weld development. In addition, tensile specimens of FS-85, ASTAR-811C, T-111, and Mo-47.5 Re had been machined at Kin-Tech (North Huntington, PA). Actual machining of the other specimen types had not been initiated. Flowcharts 1-3 detail the major processing steps each piece of material has experienced. A more detailed description of processing will be provided in a separate document [B-MT(SRME)-51]. Table 1 lists the in-process materials and finished specimens. Also included are current metallurgical condition of these materials and specimens. The available chemical analyses for these alloys at various points in the process are provided in Table 2.

  15. Atomic layer deposition on phase-shift lithography generated photoresist patterns for 1D nanochannel fabrication.

    PubMed

    Güder, Firat; Yang, Yang; Krüger, Michael; Stevens, Gregory B; Zacharias, Margit

    2010-12-01

    A versatile, low-cost, and flexible approach is presented for the fabrication of millimeter-long, sub-100 nm wide 1D nanochannels with tunable wall properties (wall thickness and material) over wafer-scale areas on glass, alumina, and silicon surfaces. This approach includes three fabrication steps. First, sub-100 nm photoresist line patterns were generated by near-field contact phase-shift lithography (NFC-PSL) using an inexpensive homemade borosilicate mask (NFC-PSM). Second, various metal oxides were directly coated on the resist patterns with low-temperature atomic layer deposition (ALD). Finally, the remaining photoresist was removed via an acetone dip, and then planar nanochannel arrays were formed on the substrate. In contrast to all the previous fabrication routes, the sub-100 nm photoresist line patterns produced by NFC-PSL are directly employed as a sacrificial layer for the creation of nanochannels. Because both the NFC-PSL and the ALD deposition are highly reproducible processes, the strategy proposed here can be regarded as a general route for nanochannel fabrication in a simplified and reliable manner. In addition, the fabricated nanochannels were used as templates to synthesize various organic and inorganic 1D nanostructures on the substrate surface. PMID:21047101

  16. Atomic layer deposition on phase-shift lithography generated photoresist patterns for 1D nanochannel fabrication.

    PubMed

    Güder, Firat; Yang, Yang; Krüger, Michael; Stevens, Gregory B; Zacharias, Margit

    2010-12-01

    A versatile, low-cost, and flexible approach is presented for the fabrication of millimeter-long, sub-100 nm wide 1D nanochannels with tunable wall properties (wall thickness and material) over wafer-scale areas on glass, alumina, and silicon surfaces. This approach includes three fabrication steps. First, sub-100 nm photoresist line patterns were generated by near-field contact phase-shift lithography (NFC-PSL) using an inexpensive homemade borosilicate mask (NFC-PSM). Second, various metal oxides were directly coated on the resist patterns with low-temperature atomic layer deposition (ALD). Finally, the remaining photoresist was removed via an acetone dip, and then planar nanochannel arrays were formed on the substrate. In contrast to all the previous fabrication routes, the sub-100 nm photoresist line patterns produced by NFC-PSL are directly employed as a sacrificial layer for the creation of nanochannels. Because both the NFC-PSL and the ALD deposition are highly reproducible processes, the strategy proposed here can be regarded as a general route for nanochannel fabrication in a simplified and reliable manner. In addition, the fabricated nanochannels were used as templates to synthesize various organic and inorganic 1D nanostructures on the substrate surface.

  17. Electric poling-assisted additive manufacturing process for PVDF polymer-based piezoelectric device applications

    NASA Astrophysics Data System (ADS)

    Lee, ChaBum; Tarbutton, Joshua A.

    2014-09-01

    This paper presents a new additive manufacturing (AM) process to directly and continuously print piezoelectric devices from polyvinylidene fluoride (PVDF) polymeric filament rods under a strong electric field. This process, called ‘electric poling-assisted additive manufacturing or EPAM, combines AM and electric poling processes and is able to fabricate free-form shape piezoelectric devices continuously. In this process, the PVDF polymer dipoles remain well-aligned and uniform over a large area in a single design, production and fabrication step. During EPAM process, molten PVDF polymer is simultaneously mechanically stresses in-situ by the leading nozzle and electrically poled by applying high electric field under high temperature. The EPAM system was constructed to directly print piezoelectric structures from PVDF polymeric filament while applying high electric field between nozzle tip and printing bed in AM machine. Piezoelectric devices were successfully fabricated using the EPAM process. The crystalline phase transitions that occurred from the process were identified by using the Fourier transform infrared spectroscope. The results indicate that devices printed under a strong electric field become piezoelectric during the EPAM process and that stronger electric fields result in greater piezoelectricity as marked by the electrical response and the formation of sharper peaks at the polar β crystalline wavenumber of the PVDF polymer. Performing this process in the absence of an electric field does not result in dipole alignment of PVDF polymer. The EPAM process is expected to lead to the widespread use of AM to fabricate a variety of piezoelectric PVDF polymer-based devices for sensing, actuation and energy harvesting applications with simple, low cost, single processing and fabrication step.

  18. Woodpile Structure Fabrication for Photonic Crystal Laser Acceleration

    SciTech Connect

    McGuinness, C.; Colby, E.; England, R. J.; Noble, R. J.; Sears, C. M.; Siemann, R.; Spencer, J.; Waltz, D.; Byer, R. L.; Plettner, T.; Cowan, B. M.

    2009-01-22

    We describe initial steps at fabricating a dielectric photonic bandgap accelerator structure designed to operate at near IR frequencies. Such a structure operating at these frequencies requires extremely small, sub-micron sized features, forcing one to use lithographic means for fabrication. A process based upon lithographic equipment at the Stanford Nanofabrication Facility has been developed and a four layer test structure has been fabricated. Unexpected problems with the final etch step, and corresponding modifications to the process flow addressing these problems, are described. Spectroscopic measurements of the structure have been taken and are compared to simulations.

  19. Woodpile Structure Fabrication for Photonic Crystal Laser Acceleration

    SciTech Connect

    McGuinness, C.; Byer, R.L.; Colby, E.; Cowan, B.M.; England, R.J.; Noble, R.J.; Plettner, T.; Sears, C.M.; Siemann, R.; Spencer, J.; Waltz, D.; /SLAC

    2010-06-30

    We describe initial steps at fabricating a dielectric photonic bandgap accelerator structure designed to operate at near IR frequencies. Such a structure operating at these frequencies requires extremely small, sub-micron sized features, forcing one to use lithographic means for fabrication. A process based upon lithographic equipment at the Stanford Nanofabrication Facility has been developed and a four layer test structure has been fabricated. Unexpected problems with the final etch step, and corresponding modifications to the process flow addressing these problems, are described. Spectroscopic measurements of the structure have been taken and are compared to simulations.

  20. Rapid Fabrication of Carbide Matrix/Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    Williams, Brian E.; Bernander, Robert E.

    2007-01-01

    Composites of zirconium carbide matrix material reinforced with carbon fibers can be fabricated relatively rapidly in a process that includes a melt infiltration step. Heretofore, these and other ceramic matrix composites have been made in a chemical vapor infiltration (CVI) process that takes months. The finished products of the CVI process are highly porous and cannot withstand temperatures above 3,000 F (approx.1,600 C). In contrast, the melt-infiltration-based process takes only a few days, and the composite products are more nearly fully dense and have withstood temperatures as high as 4,350 F (approx.2,400 C) in a highly oxidizing thrust chamber environment. Moreover, because the melt- infiltration-based process takes much less time, the finished products are expected to cost much less. Fabrication begins with the preparation of a carbon fiber preform that, typically, is of the size and shape of a part to be fabricated. By use of low-temperature ultraviolet-enhanced chemical vapor deposition, the carbon fibers in the preform are coated with one or more interfacial material(s), which could include oxides. The interfacial material helps to protect the fibers against chemical attack during the remainder of the fabrication process and against oxidation during subsequent use; it also enables slippage between the fibers and the matrix material, thereby helping to deflect cracks and distribute loads. Once the fibers have been coated with the interfacial material, the fiber preform is further infiltrated with a controlled amount of additional carbon, which serves as a reactant for the formation of the carbide matrix material. The next step is melt infiltration. The preform is exposed to molten zirconium, which wicks into the preform, drawn by capillary action. The molten metal fills most of the interstices of the preform and reacts with the added carbon to form the zirconium carbide matrix material. The zirconium does not react with the underlying fibers because they

  1. Fabrication of X-ray Spiral Masks by Laser Ablation

    NASA Astrophysics Data System (ADS)

    Peele, A. G.; Nugent, K. A.; McMahon, P. J.; Paterson, D.; Tran, C. Q.

    2002-01-01

    The authors describe microfabrication of a spiral mask modulation structure by excimer laser ablation. A multi-step fabrication using 15 separate chrome-on-quartz mask pattern is used to create a 16 step spiral staircase structure approximating the desired spiral ramp. The results of simulations and experimental results are presented.

  2. Stepped inlet optical panel

    DOEpatents

    Veligdan, James T.

    2001-01-01

    An optical panel includes stacked optical waveguides having stepped inlet facets collectively defining an inlet face for receiving image light, and having beveled outlet faces collectively defining a display screen for displaying the image light channeled through the waveguides by internal reflection.

  3. Fabrication of CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Malinovich, Yacov; Koltin, Ephie; Choen, David; Shkuri, Moshe; Ben-Simon, Meir

    1999-04-01

    In order to provide its customers with sub-micron CMOS fabrication solutions for imaging applications, Tower Semiconductor initiated a project to characterize the optical parameters of Tower's 0.5-micron process. A special characterization test chip was processed using the TS50 process. The results confirmed a high quality process for optical applications. Perhaps the most important result is the process' very low dark current, of 30-50 pA/cm2, using the entire window of process. This very low dark current characteristic was confirmed for a variety of pixel architectures. Additionally, we have succeeded to reduce and virtually eliminate the white spots on large sensor arrays. As a foundry Tower needs to support fabrication of many different imaging products. Therefore we have developed a fabrication methodology that is adjusted to the special needs of optical applications. In order to establish in-line process monitoring of the optical parameters, Tower places a scribe line optical test chip that enables wafer level measurements of the most important parameters, ensuring the optical quality and repeatability of the process. We have developed complementary capabilities like in house deposition of color filter and fabrication of very large are dice using sub-micron CMOS technologies. Shellcase and Tower are currently developing a new CMOS image sensor optical package.

  4. Fabrics for aeronautic construction

    NASA Technical Reports Server (NTRS)

    Walen, E D

    1918-01-01

    The Bureau of Standards undertook the investigation of airplane fabrics with the view of finding suitable substitutes for the linen fabrics, and it was decided that the fibers to be considered were cotton, ramie, silk, and hemp. Of these, the cotton fiber was the logical one to be given primary consideration. Report presents the suitability, tensibility and stretching properties of cotton fabric obtained by laboratory tests.

  5. Fabrication of an optical component

    DOEpatents

    Nichols, Michael A.; Aikens, David M.; Camp, David W.; Thomas, Ian M.; Kiikka, Craig; Sheehan, Lynn M.; Kozlowski, Mark R.

    2000-01-01

    A method for forming optical parts used in laser optical systems such as high energy lasers, high average power lasers, semiconductor capital equipment and medical devices. The optical parts will not damage during the operation of high power lasers in the ultra-violet light range. A blank is first ground using a fixed abrasive grinding method to remove the subsurface damage formed during the fabrication of the blank. The next step grinds and polishes the edges and forms bevels to reduce the amount of fused-glass contaminants in the subsequent steps. A loose abrasive grind removes the subsurface damage formed during the fixed abrasive or "blanchard" removal process. After repolishing the bevels and performing an optional fluoride etch, the surface of the blank is polished using a zirconia slurry. Any subsurface damage formed during the loose abrasive grind will be removed during this zirconia polish. A post polish etch may be performed to remove any redeposited contaminants. Another method uses a ceria polishing step to remove the subsurface damage formed during the loose abrasive grind. However, any residual ceria may interfere with the optical properties of the finished part. Therefore, the ceria and other contaminants are removed by performing either a zirconia polish after the ceria polish or a post ceria polish etch.

  6. The digital step edge

    NASA Technical Reports Server (NTRS)

    Haralick, R. M.

    1982-01-01

    The facet model was used to accomplish step edge detection. The essence of the facet model is that any analysis made on the basis of the pixel values in some neighborhood has its final authoritative interpretation relative to the underlying grey tone intensity surface of which the neighborhood pixel values are observed noisy samples. Pixels which are part of regions have simple grey tone intensity surfaces over their areas. Pixels which have an edge in them have complex grey tone intensity surfaces over their areas. Specially, an edge moves through a pixel only if there is some point in the pixel's area having a zero crossing of the second directional derivative taken in the direction of a non-zero gradient at the pixel's center. To determine whether or not a pixel should be marked as a step edge pixel, its underlying grey tone intensity surface was estimated on the basis of the pixels in its neighborhood.

  7. Facile fabrication of superhydrophobic Bi/Bi2O3 surfaces with hierarchical micro-nanostructures by electroless deposition or electrodeposition

    NASA Astrophysics Data System (ADS)

    Cao, Ling; Lu, Xiaoqing; Pu, Fang; Yin, Xiangle; Xia, Yue; Huang, Wei; Li, Zelin

    2014-01-01

    Superhydrophobic metallic surfaces are attracting wide interest. In this work, two facile one-step methods (displacement reaction and electrodeposition) were developed to fabricate superhydrophobic Bi/Bi2O3 surfaces with hierarchical porous dendritic structures, where the Bi2O3 cover layer was formed by surface self-passivation of the deposited Bi. The influence of various experimental parameters on the surface morphology and wettability were investigated in detail, including concentration of solutions, deposition times, and deposition potentials. A maximum contact angle about 164° can be obtained on the fabricated superhydrophobic Bi/Bi2O3 surfaces by these two methods under optimized conditions without additional surface modification.

  8. Thermal Analysis of Step 2 GPHS for Next Generation Radioisotope Power Source Missions

    NASA Astrophysics Data System (ADS)

    Pantano, David R.; Hill, Dennis H.

    2005-02-01

    The Step 2 General Purpose Heat Source (GPHS) is a slightly larger and more robust version of the heritage GPHS modules flown on previous Radioisotope Thermoelectric Generator (RTG) missions like Galileo, Ulysses, and Cassini. The Step 2 GPHS is to be used in future small radioisotope power sources, such as the Stirling Radioisotope Generator (SRG110) and the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). New features include an additional central web of Fine Weave Pierced Fabric (FWPF) graphite in the aeroshell between the two Graphite Impact Shells (GIS) to improve accidental reentry and impact survivability and an additional 0.1-inch of thickness to the aeroshell broad faces to improve ablation protection. This paper details the creation of the thermal model using Thermal Desktop and AutoCAD interfaces and provides comparisons of the model to results of previous thermal analysis models of the heritage GPHS. The results of the analysis show an anticipated decrease in total thermal gradient from the aeroshell to the iridium clads compared to the heritage results. In addition, the Step 2 thermal model is investigated under typical SRG110 boundary conditions, with cover gas and gravity environments included where applicable, to provide preliminary guidance for design of the generator. Results show that the temperatures of the components inside the GPHS remain within accepted design limits during all envisioned mission phases.

  9. Additive manufacturing of optical components

    NASA Astrophysics Data System (ADS)

    Heinrich, Andreas; Rank, Manuel; Maillard, Philippe; Suckow, Anne; Bauckhage, Yannick; Rößler, Patrick; Lang, Johannes; Shariff, Fatin; Pekrul, Sven

    2016-08-01

    The development of additive manufacturing methods has enlarged rapidly in recent years. Thereby, the work mainly focuses on the realization of mechanical components, but the additive manufacturing technology offers a high potential in the field of optics as well. Owing to new design possibilities, completely new solutions are possible. This article briefly reviews and compares the most important additive manufacturing methods for polymer optics. Additionally, it points out the characteristics of additive manufactured polymer optics. Thereby, surface quality is of crucial importance. In order to improve it, appropriate post-processing steps are necessary (e.g. robot polishing or coating), which will be discussed. An essential part of this paper deals with various additive manufactured optical components and their use, especially in optical systems for shape metrology (e.g. borehole sensor, tilt sensor, freeform surface sensor, fisheye lens). The examples should demonstrate the potentials and limitations of optical components produced by additive manufacturing.

  10. Computer-aided fabrication of a zirconia 14-unit removable dental prosthesis: a technical report.

    PubMed

    Grösser, Julian; Sachs, Caroline; Stadelmann, Markus; Schweiger, Josef; Güthe, Jan-Frederik; Beuer, Florian

    2014-01-01

    Double crown systems with primary crowns made from zirconia are used to support removable dental prostheses (RDPs). However, the fabrication of RDPs is labor-intensive and costly. Manufacturing primary and secondary crowns from zirconia with a CAD/CAM system might simplify the fabrication protocol and reduce costs. Furthermore, only ceramic materials are used in this method, providing an RDP with the highest possible biocompatibility and greatest possible esthetics. This article describes the fabrication protocol step by step. PMID:25643462

  11. Smart Fabrics Technology Development

    NASA Technical Reports Server (NTRS)

    Simon, Cory; Potter, Elliott; Potter, Elliott; McCabe, Mary; Baggerman, Clint

    2010-01-01

    Advances in Smart Fabrics technology are enabling an exciting array of new applications for NASA exploration missions, the biomedical community, and consumer electronics. This report summarizes the findings of a brief investigation into the state of the art and potential applications of smart fabrics to address challenges in human spaceflight.

  12. Fabric Fact & Fiction.

    ERIC Educational Resources Information Center

    Cohen, Andrew

    2001-01-01

    Examines the positive and negative attributes of fabric structures in providing affordable shelter for a variety of multipurpose applications, including temporary or seasonal use. Describes the three basic types of fabric structures: air-supported, frame-supported, and mast-supported. This article focuses on smaller structures of the air- and…

  13. Additive manufacturing of RF absorbers

    NASA Astrophysics Data System (ADS)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  14. Nanowires as Building Blocks to Fabricate Flexible Thermoelectric Fabric: The Case of Copper Telluride Nanowires.

    PubMed

    Zhou, Chongjian; Dun, Chaochao; Wang, Qiong; Wang, Ke; Shi, Zhongqi; Carroll, David L; Liu, Guiwu; Qiao, Guanjun

    2015-09-30

    A general approach to fabricate nanowires based inorganic/organic composite flexible thermoelectric fabric using a simple and efficacious five-step vacuum filtration process is proposed. As an excellent example, the performance of freestanding flexible thermoelectric thin film using copper telluride nanowires/polyvinylidene fluoride (Cu1.75Te NWs/PVDF = 2:1) as building block is demonstrated. By burying the Cu1.75Te NWs into the PVDF polymer agent, the flexible fabric exhibits room-temperature Seebeck coefficient and electric conductivity of 9.6 μV/K and 2490 S/cm, respectively, resulting in a power factor of 23 μW/(mK(2)) that is comparable to the bulk counterpart. Furthermore, this NW-based flexible fabric can endure hundreds of cycles of bending tests without significant performance degradation. PMID:26376703

  15. Facile approach in fabricating superhydrophobic coatings from silica-based nanocomposite

    NASA Astrophysics Data System (ADS)

    Guo, Yonggang; Wang, Qihua

    2010-10-01

    This study develops a one-step technique to synthesize various super water-repellent coatings with addition of modified silica nanoparticles. Surface topography observation showed that stacking of spherical silica nanoparticles formed primary surface roughness. The wettability of the products was investigated. It was found that the as-prepared surface possesses superhydrophobic properties not only for pure water but also for corrosive water under both acidic and basic conditions. The silica-based nanocomposite coatings can be fabricated on glass substrates and other functional engineering material surfaces, such as copper, iron, aluminum alloy, to form self-cleaning coatings.

  16. Step-Index Optical Fiber Made of Biocompatible Hydrogels.

    PubMed

    Choi, Myunghwan; Humar, Matjaž; Kim, Seonghoon; Yun, Seok-Hyun

    2015-07-15

    A biocompatible step-index optical fiber made of poly(ethylene glycol) and alginate hydrogels is demonstrated. The fabricated fiber exhibits excellent light-guiding efficiency in biological tissues. Moreover, the core of hydrogel fibers can be easily doped with functional molecules and nanoparticles for localized light emission, sensing, and therapy.

  17. A photolithographic fabrication technique for magnetohydrodynamic micropumps

    NASA Astrophysics Data System (ADS)

    Kuenstner, Stephen; Baylor, Martha-Elizabeth

    2014-03-01

    Magnetohydrodynamic (MHD) devices use perpendicular electric and magnetic fields to exert a Lorentz body force on a conducting fluid. Miniaturized MHD devices have been used to create pumps, stirrers, heat exchangers, and microfluidic networks. Compared to mechanical micropumps, MHD micropumps are appealing because they require no moving parts, which simplifies fabrication, and because they are amenable to electronic control. This abstract reports the fabrication and testing of a centimeter-scale MHD pump using a thiol-ene/methacrylate-based photopolymer and mask-based photolithographic technique. Pumps like this one could simplify the fabrication of sophisticated optofluidic devices, including liquid-core, liquid cladding (L2) waveguides, which are usually created with PDMS using stamps, or etched into silicon wafers. The photolithographic technique demonstrated here requires only one masking step to create fluid channels with complex geometries.

  18. Single-step route to diamond-nanotube composite

    PubMed Central

    2012-01-01

    Candle wax was used as a precursor for the production of a diamond-nanotube composite in a single step. The composite films were fabricated by sulfur-assisted hot-filament chemical vapor deposition technique. The morphology of the composite films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectra of the films show characteristic diamond band at 1,332 cm−1, D-band around 1,342 cm−1, and graphitic G-band around 1,582 cm−1. The electron energy-loss spectroscopy recorded at the carbon K-edge region shows signature features of diamond and carbon nanotube in the fabricated material. The ability to synthesize diamond-nanotube composites at relatively low temperatures by a single-step process opens up new possibilities for the fabrication of nanoelectronic devices. PMID:23013660

  19. Single-step route to diamond-nanotube composite

    NASA Astrophysics Data System (ADS)

    Varshney, Deepak; Ahmadi, Majid; Guinel, Maxime J.-F.; Weiner, Brad R.; Morell, Gerardo

    2012-09-01

    Candle wax was used as a precursor for the production of a diamond-nanotube composite in a single step. The composite films were fabricated by sulfur-assisted hot-filament chemical vapor deposition technique. The morphology of the composite films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectra of the films show characteristic diamond band at 1,332 cm-1, D-band around 1,342 cm-1, and graphitic G-band around 1,582 cm-1. The electron energy-loss spectroscopy recorded at the carbon K-edge region shows signature features of diamond and carbon nanotube in the fabricated material. The ability to synthesize diamond-nanotube composites at relatively low temperatures by a single-step process opens up new possibilities for the fabrication of nanoelectronic devices.

  20. Acta Clinica Croatica: progress of a journal step by step.

    PubMed

    Ramljak, Gordana

    2014-03-01

    The journal Acta Clinica Croatica (ACC) was founded in 1962 under the title Anali Bolnice Dr. M. Stojanović. In 1995, the title of the journal was changed into its present form and ever since all papers have been published in English. In 2000, the electronic (online) edition of the ACC was released in addition to the print version. The paper presents development of the journal from 1962 to 2012 based on the analysis of the following SCOPUS citation index parameters: type and number of documents published in the journal; number of citations; and number of domestic and foreign authors. The studied period was analyzed in three time segments: the period from 1995 to 1999, the period from 2000 to 2006 and the period from 2007 to 2012. The same parameters were analyzed in the Web of Science/SCI-Expanded bibliographic and citation index for the 2007-2012 period. The increasing number of documents, authors (both domestic and foreign) and citations demonstrates gradual rise in the quality, visibility and impact of the journal. The fifty years of experience show that a goal, at first very distant and almost unachievable, may be reached by progressing step by step.

  1. New photolithography stepping machine

    SciTech Connect

    Hale, L.; Klingmann, J.; Markle, D.

    1995-03-08

    A joint development project to design a new photolithography steeping machine capable of 150 nanometer overlay accuracy was completed by Ultratech Stepper and the Lawrence Livermore National Laboratory. The principal result of the project is a next-generation product that will strengthen the US position in step-and-repeat photolithography. The significant challenges addressed and solved in the project are the subject of this report. Design methods and new devices that have broader application to precision machine design are presented in greater detail while project specific information serves primarily as background and motivation.

  2. Steps to the moon

    USGS Publications Warehouse

    ,; Dale, Alvin E.

    1976-01-01

    On July 20, 1969, man walked on the surface of the Moon and began a new chapter of his studies that will eventually disclose the geologic nature of the Earth's nearest neighbor. Although he has finally reached the Moon and sampled its substance, much work and study remain before he will know the full scientific significance of the first landing. This booklet briefly summarizes the steps man has taken to understand the Moon and what he thinks he has learned to date as a result of his centuries-long speculations and studies.

  3. Experimentation: the next step

    PubMed Central

    Marinker, Marshall

    1987-01-01

    General practice has entered a period of accelerating change, and those responsible for planning its development now put forward a variety of promising proposals. Unless provision is made for large scale experimentation and scientific evaluation, the direction of future change will be determined not by evidence but by rhetoric. A framework for creating and evaluating a substantial programme of experimentation is suggested. The programme is the logical next step in the process of change which was given impetus by the publication of the government green paper. It should be seen as a professional, moral and political priority. PMID:3681850

  4. Method for fabricating pixelated silicon device cells

    SciTech Connect

    Nielson, Gregory N.; Okandan, Murat; Cruz-Campa, Jose Luis; Nelson, Jeffrey S.; Anderson, Benjamin John

    2015-08-18

    A method, apparatus and system for flexible, ultra-thin, and high efficiency pixelated silicon or other semiconductor photovoltaic solar cell array fabrication is disclosed. A structure and method of creation for a pixelated silicon or other semiconductor photovoltaic solar cell array with interconnects is described using a manufacturing method that is simplified compared to previous versions of pixelated silicon photovoltaic cells that require more microfabrication steps.

  5. New polymorphous computing fabric.

    SciTech Connect

    Wolinski, C.; Gokhale, M.; McCabe, K. P.

    2002-01-01

    This paper introduces a new polymorphous computing Fabric well suited to DSP and Image Processing and describes its implementation on a Configurable System on a Chip (CSOC). The architecture is highly parameterized and enables customization of the synthesized Fabric to achieve high performance for a specific class of application. For this reason it can be considered to be a generic model for hardware accelerator synthesis from a high level specification. Another important innovation is the Fabric uses a global memory concept, which gives the host processor random access to all the variables and instructions on the Fabric. The Fabric supports different computing models including MIMD, SPMD and systolic flow and permits dynamic reconfiguration. We present a specific implementation of a bank of FIR filters on a Fabric composed of 52 cells on the Altera Excalibur ARM running at 33 MHz. The theoretical performance of this Fabric is 1.8 GMACh. For the FIR application we obtain 1.6 GMAC/s real performance. Some automatic tools have been developed like the tool to provide a host access utility and assembler.

  6. SPAR-H Step-by-Step Guidance

    SciTech Connect

    W. J. Galyean; A. M. Whaley; D. L. Kelly; R. L. Boring

    2011-05-01

    This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

  7. Designing Robust Hierarchically Textured Oleophobic Fabrics.

    PubMed

    Kleingartner, Justin A; Srinivasan, Siddarth; Truong, Quoc T; Sieber, Michael; Cohen, Robert E; McKinley, Gareth H

    2015-12-01

    Commercially available woven fabrics (e.g., nylon- or PET-based fabrics) possess inherently re-entrant textures in the form of cylindrical yarns and fibers. We analyze the liquid repellency of woven and nanotextured oleophobic fabrics using a nested model with n levels of hierarchy that is constructed from modular units of cylindrical and spherical building blocks. At each level of hierarchy, the density of the topographical features is captured using a dimensionless textural parameter D(n)*. For a plain-woven mesh comprised of chemically treated fiber bundles (n = 2), the tight packing of individual fibers in each bundle (D2* ≈ 1) imposes a geometric constraint on the maximum oleophobicity that can be achieved solely by modifying the surface energy of the coating. For liquid droplets contacting such tightly bundled fabrics with modified surface energies, we show that this model predicts a lower bound on the equilibrium contact angle of θ(E) ≈ 57° below which the Cassie–Baxter to Wenzel wetting transition occurs spontaneously, and this is validated experimentally. We demonstrate how the introduction of an additional higher order micro-/nanotexture onto the fibers (n = 3) is necessary to overcome this limit and create more robustly nonwetting fabrics. Finally, we show a simple experimental realization of the enhanced oleophobicity of fabrics by depositing spherical microbeads of poly(methyl methacrylate)/fluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS) onto the fibers of a commercial woven nylon fabric. PMID:26473386

  8. Designing Robust Hierarchically Textured Oleophobic Fabrics.

    PubMed

    Kleingartner, Justin A; Srinivasan, Siddarth; Truong, Quoc T; Sieber, Michael; Cohen, Robert E; McKinley, Gareth H

    2015-12-01

    Commercially available woven fabrics (e.g., nylon- or PET-based fabrics) possess inherently re-entrant textures in the form of cylindrical yarns and fibers. We analyze the liquid repellency of woven and nanotextured oleophobic fabrics using a nested model with n levels of hierarchy that is constructed from modular units of cylindrical and spherical building blocks. At each level of hierarchy, the density of the topographical features is captured using a dimensionless textural parameter D(n)*. For a plain-woven mesh comprised of chemically treated fiber bundles (n = 2), the tight packing of individual fibers in each bundle (D2* ≈ 1) imposes a geometric constraint on the maximum oleophobicity that can be achieved solely by modifying the surface energy of the coating. For liquid droplets contacting such tightly bundled fabrics with modified surface energies, we show that this model predicts a lower bound on the equilibrium contact angle of θ(E) ≈ 57° below which the Cassie–Baxter to Wenzel wetting transition occurs spontaneously, and this is validated experimentally. We demonstrate how the introduction of an additional higher order micro-/nanotexture onto the fibers (n = 3) is necessary to overcome this limit and create more robustly nonwetting fabrics. Finally, we show a simple experimental realization of the enhanced oleophobicity of fabrics by depositing spherical microbeads of poly(methyl methacrylate)/fluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS) onto the fibers of a commercial woven nylon fabric.

  9. A New Process for Fabricating Random Silicon Nanotips

    NASA Technical Reports Server (NTRS)

    Manohara, Harish

    2004-01-01

    An improved process for the fabrication of random arrays of silicon nanotips has been demonstrated to be feasible. Relative to other such processes, this process offers advantages of low cost and simplicity. Moreover, this process can readily be combined with other processes used to fabricate integrated circuits and other monolithic silicon structures. Arrays of silicon nanotips are subjects of research and development efforts directed toward utilizing them as field emitters in flat-panel displays, vacuum microelectronics, and microwave devices. Other silicon-nanotip-fabrication processes developed thus far predominantly include lithography, etching, and/or elaborate deposition steps followed by oxide sharpening steps and are both process intensive as well as expensive. In addition to being cheaper and simpler, the present process can efficiently produce silicon nanotips that range in height from a few microns to several tens of microns and are distributed over large areas. The process mentioned here can be summarized as consisting of (1) the growth of micro-etch masks on a silicon substrate, followed by (2) etching away of the masks, along with some of the substrate, to make an array of sharp tips. In the first step of the process, a cleaned silicon substrate is subjected to reactive ion etching (RIE) in a certain mixture of oxygen and carbon tetrafluoride under radio-frequency excitation. This process step results in the growth of fluorine based compounds in the form of stumps randomly distributed on the substrate. These stumps are known in the art as polymer RIE grass. The dimensions of these stumps are of the order of hundreds of nanometers, the exact values depending on process time and gas composition. The areal density of the stumps decreases with increasing process time as they grow and merge with neighboring stumps. These stumps constitute the micro-etch masks for the next step of the process. In the second step of the process, the substrate covered with

  10. Comparison one-step procedure with two-step procedure in percutaneous nephrolithotomy.

    PubMed

    Chen, Szu-Han; Wu, Wen-Jeng; Chou, Yii-Her; Yeh, Hsin-Chih; Tsai, Chia-Chun; Chueh, Kuang-Shun; Hou, Nien-Ting; Chiu, Siou-Jin; Tu, Hung-Pin; Li, Ching-Chia

    2014-04-01

    The aim of this study was to compare the effects of one-step percutaneous nephrolithotomy (PCNL) by the urologist alone and two-step PCNL by cooperating with the radiologist. We included 168 patients who underwent surgery by the same surgeon, 83 who underwent two-step PCNL, in which percutaneous nephrostomy insertion was performed by the radiologists on the day before endo-surgery, and 85 who underwent one-step PCNL, which involved the creation of a nephrostomy tract and performing the PCNL at the same time in the operating room, by a urologist. We compared the perioperative and postoperative parameters between these two groups. The result revealed that there were no significant differences between one-step and two-step PCNL in the decreases in haemoglobin level and blood transfusion volume, and the hospital stay was shorter in the one-step PCNL group. In addition, the one-step PCNL group was associated with significantly lower visual analogue score (VAS), which were 2.3, 1.1, and 0.4 on the post-operative days 1, 2, and 3, respectively, compared with 3.2, 1.7, and 1.0 in the two-step PCNL group. The number of parenteral analgesic prescriptions was fewer in the one-step PCNL group (0.8 ± 1.1 amps/vials) than in the two-step PCNL group (4.1 ± 2.4 amps/vials). Furthermore, different stone locations barely affected VAS and analgesic administrations. The results indicate that the one-step PCNL by the urologist alone, compared to two-step PCNL with the radiologist, has better wound pain outcome and shorter hospital stay with comparable successful rate and complication grade.

  11. Flexible Metal-Fabric Radiators

    NASA Technical Reports Server (NTRS)

    Cross, Cynthia; Nguyen, Hai D.; Ruemmele, Warren; Andish, Kambiz K.; McCalley, Sean

    2005-01-01

    Flexible metal-fabric radiators have been considered as alternative means of dissipating excess heat from spacecraft and space suits. The radiators also may be useful in such special terrestrial applications as rejecting heat from space-suit-like protective suits worn in hot work environments. In addition to flexibility and consequent ease of deployment and installation on objects of varying sizes and shapes, the main advantages of these radiators over conventional rigid radiators are that they weigh less and occupy less volume for a given amount of cooling capacity. A radiator of this type includes conventional stainless-steel tubes carrying a coolant fluid. The main radiating component consists of a fabric of interwoven aluminum-foil strips bonded to the tubes by use of a proprietary process. The strip/tube bonds are strong and highly thermally conductive. Coolant is fed to and from the tubes via flexible stainless-steel manifolds designed to accommodate flexing of, and minimize bending forces on, the fabric. The manifolds are sized to minimize pressure drops and distribute the flow of coolant evenly to all the tubes. The tubes and manifolds are configured in two independent flow loops for operational flexibility and protective redundancy.

  12. Laser-assisted fabrication of single-layer flexible touch sensor

    PubMed Central

    Son, Seokwoo; Park, Jong Eun; Lee, Joohyung; Yang, Minyang; Kang, Bongchul

    2016-01-01

    Single-layer flexible touch sensor that is designed for the indium-tin-oxide (ITO)-free, bendable, durable, multi-sensible, and single layer transparent touch sensor was developed via a low-cost and one-step laser-induced fabrication technology. To this end, an entirely novel approach involving material, device structure, and even fabrication method was adopted. Conventional metal oxides based multilayer touch structure was substituted by the single layer structure composed of integrated silver wire networks of sensors and bezel interconnections. This structure is concurrently fabricated on a glass substitutive plastic film via the laser-induced fabrication method using the low-cost organometallic/nanoparticle hybrid complex. In addition, this study addresses practical solutions to heterochromia and interference problem with a color display unit. As a result, a practical touch sensor is successfully demonstrated through resolving the heterochromia and interference problems with color display unit. This study could provide the breakthrough for early realization of wearable device. PMID:27703204

  13. A novel method of fabricating carbon nanotubes-polydimethylsiloxane composite electrodes for electrocardiography.

    PubMed

    Liu, Benyan; Chen, Yingmin; Luo, Zhangyuan; Zhang, Wenzan; Tu, Quan; Jin, Xun

    2015-01-01

    Polymer-based flexible electrodes are receiving much attention in medical applications due to their good wearing comfort. The current fabrication methods of such electrodes are not widely applied. In this study, polydimethylsiloxane (PDMS) and conductive additives of carbon nanotubes (CNTs) were employed to fabricate composite electrodes for electrocardiography (ECG). A three-step dispersion process consisting of ultrasonication, stirring, and in situ polymerization was developed to yield homogenous CNTs-PDMS mixtures. The CNTs-PDMS mixtures were used to fabricate CNTs-PDMS composite electrodes by replica technology. The influence of ultrasonication time and CNT concentration on polymer electrode performance was evaluated by impedance and ECG measurements. The signal amplitude of the electrodes prepared using an ultrasonication time of 12 h and CNT content of 5 wt% was comparable to that of commercial Ag/AgCl electrodes. The polymer electrodes were easily fabricated by conventional manufacturing techniques, indicating a potential advantage of reduced cost for mass production.

  14. Mechanical Design and Fabrication of a New RF Power Amplifier for LANSCE

    SciTech Connect

    Chen, Zukun

    2011-01-01

    A Full-scale prototype of a new 201.25 MHz RF Final Power Amplifier (FPA) for Los Alamos Neutron Science Center (LANSCE) has been designed, fabricated, assembled and installed in the test facility. This prototype was successfully tested and met the physics and electronics design criteria. The team faced design and manufacturing challenges, having a goal to produce 2 MW peak power at 13% duty factor, at the elevation of over 2 km in Los Alamos. The mechanical design of the final power amplifier was built around a Thales TH628 Diacrode{sup R}, a state-of-art tetrode power tube. The main structure includes Input circuit, Output circuit, Grid decoupling circuit, Output coupler, Tuning pistons, and a cooling system. Many types of material were utilized to make this new RF amplifier. The fabrication processes of the key components were completed in the Prototype Fabrication Division shop at Los Alamos National Laboratory. The critical plating procedures were achieved by private industry. The FPA mass is nearly 600 kg and installed in a beam structural support stand. In this paper, we summarize the FPA design basis and fabrication, plating, and assembly process steps with necessary lifting and handling fixtures. In addition, to ensure the quality of the FPA support structure a finite element analysis with seismic design forces has also been carried out.

  15. Laser-assisted fabrication of single-layer flexible touch sensor

    NASA Astrophysics Data System (ADS)

    Son, Seokwoo; Park, Jong Eun; Lee, Joohyung; Yang, Minyang; Kang, Bongchul

    2016-10-01

    Single-layer flexible touch sensor that is designed for the indium-tin-oxide (ITO)-free, bendable, durable, multi-sensible, and single layer transparent touch sensor was developed via a low-cost and one-step laser-induced fabrication technology. To this end, an entirely novel approach involving material, device structure, and even fabrication method was adopted. Conventional metal oxides based multilayer touch structure was substituted by the single layer structure composed of integrated silver wire networks of sensors and bezel interconnections. This structure is concurrently fabricated on a glass substitutive plastic film via the laser-induced fabrication method using the low-cost organometallic/nanoparticle hybrid complex. In addition, this study addresses practical solutions to heterochromia and interference problem with a color display unit. As a result, a practical touch sensor is successfully demonstrated through resolving the heterochromia and interference problems with color display unit. This study could provide the breakthrough for early realization of wearable device.

  16. Other Fabric Structures

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Architects, engineers and building owners are turning increasingly to fabric structures because of their aesthetic appeal, relatively low initial cost, low maintenance outlays, energy efficiency and good space utilization. Several examples are shown.

  17. Speedo Fabric Testing

    NASA Video Gallery

    Because the physical laws of motion for moving a body through water are the same as moving a vehicle through air, NASA aeronautics experts test the drag effects of different fabrics for Olympic-bou...

  18. Additive Manufacturing of Hybrid Circuits

    NASA Astrophysics Data System (ADS)

    Sarobol, Pylin; Cook, Adam; Clem, Paul G.; Keicher, David; Hirschfeld, Deidre; Hall, Aaron C.; Bell, Nelson S.

    2016-07-01

    There is a rising interest in developing functional electronics using additively manufactured components. Considerations in materials selection and pathways to forming hybrid circuits and devices must demonstrate useful electronic function; must enable integration; and must complement the complex shape, low cost, high volume, and high functionality of structural but generally electronically passive additively manufactured components. This article reviews several emerging technologies being used in industry and research/development to provide integration advantages of fabricating multilayer hybrid circuits or devices. First, we review a maskless, noncontact, direct write (DW) technology that excels in the deposition of metallic colloid inks for electrical interconnects. Second, we review a complementary technology, aerosol deposition (AD), which excels in the deposition of metallic and ceramic powder as consolidated, thick conformal coatings and is additionally patternable through masking. Finally, we show examples of hybrid circuits/devices integrated beyond 2-D planes, using combinations of DW or AD processes and conventional, established processes.

  19. Stair-stepped Mound

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-429, 22 July 2003

    This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a stair-stepped mound of sedimentary rock (right of center) on the floor of a large impact crater in western Arabia Terra near 11.0oN, 4.4oW. Sedimentary rock outcrops are common in the craters of this region. The repeated thickness and uniformity of the layers that make up this mound suggest that their depositional environment was one in which cyclic or episodic events occurred over some period of time. The sediments might have been deposited in a lake, or they may have settled directly out of the atmosphere. Most of the layered material was later eroded away, leaving this circular mound and the other nearby mesas and knobs. The image is illuminated by sunlight from the lower left.

  20. Controlling linewidth roughness in step and flash imprint lithography

    NASA Astrophysics Data System (ADS)

    Schmid, Gerard M.; Khusnatdinov, Niyaz; Brooks, Cynthia B.; LaBrake, Dwayne; Thompson, Ecron; Resnick, Douglas J.; Owens, Jordan; Ford, Arnie; Sasaki, Shiho; Toyama, Nobuhito; Kurihara, Masaaki; Hayashi, Naoya; Kobayashi, Hideo; Sato, Takashi; Nagarekawa, Osamu; Hart, Mark W.; Gopalakrishnan, Kailash; Shenoy, Rohit; Jih, Ron; Zhang, Ying; Sikorski, Edmund; Rothwell, Mary Beth; Yoshitake, Shusuke; Sunaoshi, Hitoshi; Yasui, Kenichi

    2008-04-01

    Despite the remarkable progress made in extending optical lithography to deep sub-wavelength imaging, the limit for the technology seems imminent. At 22nm half pitch design rules, neither very high NA tools (NA 1.6), nor techniques such as double patterning are likely to be sufficient. One of the key challenges in patterning features with these dimensions is the ability to minimize feature roughness while maintaining reasonable process throughput. This limitation is particularly challenging for electron and photon based NGL technologies, where fast chemically amplified resists are used to define the patterned images. Control of linewidth roughness (LWR) is critical, since it adversely affects device speed and timing in CMOS circuits. Imprint lithography has been included on the ITRS Lithography Roadmap at the 32 and 22 nm nodes. This technology has been shown to be an effective method for replication of nanometer-scale structures from a template (imprint mask). As a high fidelity replication process, the resolution of imprint lithography is determined by the ability to create a master template having the required dimensions. Although the imprint process itself adds no additional linewidth roughness to the patterning process, the burden of minimizing LWR falls to the template fabrication process. Non chemically amplified resists, such as ZEP520A, are not nearly as sensitive but have excellent resolution and can produce features with very low LWR. The purpose of this paper is to characterize LWR for the entire imprint lithography process, from template fabrication to the final patterned substrate. Three experiments were performed documenting LWR in the template, imprint, and after pattern transfer. On average, LWR was extremely low (less than 3nm, 3σ), and independent of the processing step and feature size.

  1. Linewidth roughness characterization in step and flash imprint lithography

    NASA Astrophysics Data System (ADS)

    Schmid, Gerard M.; Khusnatdinov, Niyaz; Brooks, Cynthia B.; LaBrake, Dwayne; Thompson, Ecron; Resnick, Douglas J.

    2008-05-01

    Despite the remarkable progress made in extending optical lithography to deep sub-wavelength imaging, the limit for the technology seems imminent. At 22nm half pitch design rules, neither very high NA tools (NA 1.6), nor techniques such as double patterning are likely to be sufficient. One of the key challenges in patterning features with these dimensions is the ability to minimize feature roughness while maintaining reasonable process throughput. This limitation is particularly challenging for electron and photon based NGL technologies, where fast chemically amplified resists are used to define the patterned images. Control of linewidth roughness (LWR) is critical, since it adversely affects device speed and timing in CMOS circuits. Imprint lithography has been included on the ITRS Lithography Roadmap at the 32 and 22 nm nodes. This technology has been shown to be an effective method for replication of nanometer-scale structures from a template (imprint mask). As a high fidelity replication process, the resolution of imprint lithography is determined by the ability to create a master template having the required dimensions. Although the imprint process itself adds no additional linewidth roughness to the patterning process, the burden of minimizing LWR falls to the template fabrication process. Non chemically amplified resists, such as ZEP520A, are not nearly as sensitive but have excellent resolution and can produce features with very low LWR. The purpose of this paper is to characterize LWR for the entire imprint lithography process, from template fabrication to the final patterned substrate. Three experiments were performed documenting LWR in the template, imprint, and after pattern transfer. On average, LWR was extremely low (less than 3nm, 3σ), and independent of the processing step and feature size.

  2. Autoclavable addition polyimides for 371 C composite applications

    NASA Technical Reports Server (NTRS)

    Vannucci, R. D.; Malarik, D.; Papadopoulos, D.; Waters, J.

    1990-01-01

    Studies were conducted to improve the thermo-oxidative stability (TOS) of PMR type polyimides by the substitution of para-aminostyrene (PAS) for the nadic ester endcap in second generation PMR polyimides (PMR-2). The nadic endcap which provides the PMR polyimides with their relative ease of fabrication, both by limiting the molecular weight of the prepolymer and by undergoing the final addition cure without volatiles, is also the weak link with regard to TOS. A polyimide formulated with PAS endcaps, called V-CAP, utilizes a two step reaction sequence similar to that of the PMR polyimides and can be easily autoclave molded into low void composite materials. Resin studies included two formulations of both PMR-2 and V-CAP, corresponding to n = 9 and n = 14 prepolymer stoichiometry. Unidirectional reinforced T40R graphite fiber laminates were fabricated from each of the resins was post-cured in either air at 385 C or nitrogen at 400 C. Composite specimens were aged in air at 371 C and mechanical properties were measured at 371 C before and after exposure.

  3. Autoclavable addition polyimides for 371 C composite applications

    NASA Technical Reports Server (NTRS)

    Vannucci, R. D.; Malarik, D. C.; Papadapoulos, D. S.; Waters, J. F.

    1990-01-01

    Studies were conducted to improve the thermo-oxidative stability (TOS) of PMR type polyimides by the substitution of para-aminostyrene (PAS) for the nadic ester endcap in second generation PMR polyimides (PMR-2). The nadic endcap which provides the PMR polyimides with their relative ease of fabrication, both by limiting the molecular weight of the prepolymer and by undergoing the final addition cure without volatiles, is also the weak link with regard to TOS. A polyimide formulated with PAS endcaps, called V-CAP, utilizes a two step reaction sequence similar to that of the PMR polyimides and can be easily autoclave molded into low void composite materials. Resin studies included two formulations of both PMR-2 and V-CAP, corresponding to n=9 and n=14 prepolymer stoichiometry. Unidirectional reinforced T40R graphite fiber laminates were fabricated from each of the resins was post-cured in either air at 385 C or nitrogen at 400 C. Composite specimens were aged in air at 371 C and mechanical properties were measured at 371 C before and after exposure.

  4. Fabrication of Silica Ultra High Quality Factor Microresonators

    PubMed Central

    Maker, Ashley J.; Armani, Andrea M.

    2012-01-01

    Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7 The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q>100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment. Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment. Introduction An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality

  5. Superabsorbent Multilayer Fabric

    NASA Technical Reports Server (NTRS)

    Coreale, J. V.; Dawn, F. S.

    1982-01-01

    Material contains gel-forming polymer and copolymer that absorb from 70 to 200 times their weight of liquid. Superabsorbent Polymer and Copolymer form gels to bind and retain liquid in multiply fabric. Until reaction between liquid and absorbent masses forms gel, backing layer retains liquids within fabric; also allows material to "breathe." Possible applications include baby diapers, female hygiene napkins, and hospital bedpads. Might also have uses in improvement of dry soil.

  6. Fabricated torque shaft

    DOEpatents

    Mashey, Thomas Charles

    2002-01-01

    A fabricated torque shaft is provided that features a bolt-together design to allow vane schedule revisions with minimal hardware cost. The bolt-together design further facilitates on-site vane schedule revisions with parts that are comparatively small. The fabricated torque shaft also accommodates stage schedules that are different one from another in non-linear inter-relationships as well as non-linear schedules for a particular stage of vanes.

  7. Nuclear Fabrication Consortium

    SciTech Connect

    Levesque, Stephen

    2013-04-05

    This report summarizes the activities undertaken by EWI while under contract from the Department of Energy (DOE) Office of Nuclear Energy (NE) for the management and operation of the Nuclear Fabrication Consortium (NFC). The NFC was established by EWI to independently develop, evaluate, and deploy fabrication approaches and data that support the re-establishment of the U.S. nuclear industry: ensuring that the supply chain will be competitive on a global stage, enabling more cost-effective and reliable nuclear power in a carbon constrained environment. The NFC provided a forum for member original equipment manufactures (OEM), fabricators, manufacturers, and materials suppliers to effectively engage with each other and rebuild the capacity of this supply chain by : Identifying and removing impediments to the implementation of new construction and fabrication techniques and approaches for nuclear equipment, including system components and nuclear plants. Providing and facilitating detailed scientific-based studies on new approaches and technologies that will have positive impacts on the cost of building of nuclear plants. Analyzing and disseminating information about future nuclear fabrication technologies and how they could impact the North American and the International Nuclear Marketplace. Facilitating dialog and initiate alignment among fabricators, owners, trade associations, and government agencies. Supporting industry in helping to create a larger qualified nuclear supplier network. Acting as an unbiased technology resource to evaluate, develop, and demonstrate new manufacturing technologies. Creating welder and inspector training programs to help enable the necessary workforce for the upcoming construction work. Serving as a focal point for technology, policy, and politically interested parties to share ideas and concepts associated with fabrication across the nuclear industry. The report the objectives and summaries of the Nuclear Fabrication Consortium

  8. One-step process for superhydrophobic metallic surfaces by wire electrical discharge machining.

    PubMed

    Bae, Won Gyu; Song, Ki Young; Rahmawan, Yudi; Chu, Chong Nam; Kim, Dookon; Chung, Do Kwan; Suh, Kahp Y

    2012-07-25

    We present a direct one-step method to fabricate dual-scale superhydrophobic metallic surfaces using wire electrical discharge machining (WEDM). A dual-scale structure was spontaneously formed by the nature of exfoliation characteristic of Al 7075 alloy surface during WEDM process. A primary microscale sinusoidal pattern was formed via a programmed WEDM process, with the wavelength in the range of 200 to 500 μm. Notably, a secondary roughness in the form of microcraters (average roughness, Ra: 4.16 to 0.41 μm) was generated during the exfoliation process without additional chemical treatment. The low surface energy of Al 7075 alloy (γ = 30.65 mJ/m(2)) together with the presence of dual-scale structures appears to contribute to the observed superhydrophobicity with a static contact angle of 156° and a hysteresis less than 3°. To explain the wetting characteristics on dual-scale structures, we used a simple theoretical model. It was found that Cassie state is likely to present on the secondary roughness in all fabricated surfaces. On the other hand, either Wenzel or Cassie state can present on the primary roughness depending on the characteristic length of sinusoidal pattern. In an optimal condition of the serial cutting steps with applied powers of ∼30 and ∼8 kW, respectively, a stable, superhydrophobic metallic surface was created with a sinusoidal pattern of 500 μm wavelength.

  9. Fabric space radiators

    SciTech Connect

    Antoniak, Z.I.; Krotiuk, W.J.; Webb, B.J.; Prater, J.T.; Bates, J.M.

    1988-01-01

    Future Air Force space missions will require thermal radiators that both survive in the hostile space environment and stow away for minimal bulk during launch. Advances in all aspects of radiator design, construction, and analysis will be necessary to enable such future missions. Currently, the best means for obtaining high strength along with flexibility is through structures known as fabrics. The development of new materials and bonding techniques has extended the application range of fabrics into areas traditionally dominated by monolithic and/or metallic structures. Given that even current spacecraft heat rejection considerations tend to dominate spacecraft design and mass, the larger and more complex designs of the future face daunting challenges in thermal control. Ceramic fabrics bonded to ultra-thin metal liners (foils) have the potential of achieving radiator performance levels heretofore unattainable, and of readily matching the advances made in other branches of spacecraft design. The research effort documented here indicates that both pumped loops and heat pipes constructed in ceramic fabrics stand to benefit in multiple ways. Flexibility and low mass are the main advantages exhibited by fabric radiators over conventional metal ones. We feel that fabric radiators have intrinsic merits not possessed by any other radiator design and need to be researched further. 26 refs., 16 figs., 17 tabs.

  10. Superamphiphilic Janus fabric.

    PubMed

    Lim, Ho Sun; Park, Song Hee; Koo, Song Hee; Kwark, Young-Je; Thomas, Edwin L; Jeong, Youngjin; Cho, Jeong Ho

    2010-12-21

    Janus fabrics with superamphiphilicity were fabricated via electrospinning of polyacrylonitrile (PAN). PAN nanofibrous mats were formed on an aluminum foil substrate and then thermally treated to cause hydrolysis. An identical PAN solution was subsequently electrospun onto the hydrolyzed PAN layer, followed by peeling off of the bicomposite film from the collector substrate to produce a free-standing Janus fabric. On one side, the electrospun PAN mat exhibited superhydrophobic properties, with a water contact angle of 151.2°, whereas the initially superhydrophobic PAN sheet on the opposite side of the fabric was converted to a superhydrophilic surface (water contact angle of 0°) through hydrolysis of the surface functional groups induced by the thermal treatment. The resulting Janus fabrics exhibited both superhydrophobicity, repelling water on the one side, and superhydrophilicity, absorbing water on the other side. The organic solvent resistance of the PAN nanofibrous sheets was remarkably improved by incorporation of a tetraethyl orthosilicate. This facile and simple technique introduces a new route for the design and development of functional smart, robust fabrics from an inexpensive, commercially available polymer.

  11. Step bunching and ordering induced by step-edge barriers

    NASA Astrophysics Data System (ADS)

    Zhao, Yuegang; Liu, Feng; Tersoff, Jerry; Lagally, Max G.

    2000-03-01

    We derive the equation of motion of steps for step flow growth under the influence of both misfit strain and step-edge barriers. An energy barrier at a step for an atom arriving from the lower terrace causes a step bunching instability. Simulation results show that the bunching is predominantly driven by a coalescence mechanism, leading to multiple transient stages of metastable step bunch arrays, with average bunch size of 2, 4, and 8 steps. The bunch array in these transient stages exhibits a surprisingly good long-range order. Similar kinetic step-bunch ordering has been seen in a a recent experiment[1]. Reference: [1]: C. Schelling, G. Springholz, and F. Schäffler, Phys. Rev. Letts, 83(995)1999.

  12. Metal Additive Manufacturing: A Review

    NASA Astrophysics Data System (ADS)

    Frazier, William E.

    2014-06-01

    This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential.

  13. Green Schools Energy Project: A Step-by-Step Manual.

    ERIC Educational Resources Information Center

    Quigley, Gwen

    This publication contains a step-by-step guide for implementing an energy-saving project in local school districts: the installation of newer, more energy-efficient "T-8" fluorescent tube lights in place of "T-12" lights. Eleven steps are explained in detail: (1) find out what kind of lights the school district currently uses; (2) form a group to…

  14. Method of fabricating vertically aligned group III-V nanowires

    DOEpatents

    Wang, George T; Li, Qiming

    2014-11-25

    A top-down method of fabricating vertically aligned Group III-V micro- and nanowires uses a two-step etch process that adds a selective anisotropic wet etch after an initial plasma etch to remove the dry etch damage while enabling micro/nanowires with straight and smooth faceted sidewalls and controllable diameters independent of pitch. The method enables the fabrication of nanowire lasers, LEDs, and solar cells.

  15. Fabrication of lightweight Si/SiC LIDAR mirrors

    NASA Technical Reports Server (NTRS)

    Goela, Jitendra S.; Taylor, Raymond L.

    1991-01-01

    A new, chemical vapor deposition (CVD) process was developed for fabricating lightweight, polycrystalline silicon/silicon-carbide (Si/SiC) mirrors. The process involves three CVD steps: (1) to produce the mirror faceplate; (2) to form the lightweight backstructure, which is deposited integral to the faceplate; and (3) to deposit a layer of optical-grade material, e.g., Si, onto the front surface of the faceplate. The mirror figure and finish are fabricated into the faceplate.

  16. Stepping Up Your Game

    ERIC Educational Resources Information Center

    Rothery, Thomas G.

    2007-01-01

    To help struggling seniors with the expectations of a high school precalculus course, their lack of confidence, and the "new" intimidation they feel in the classroom, the teacher discusses additional study skills necessary for performing well in the mathematics classroom. The author compares studying mathematics to the practice necessary to…

  17. Additive lattice kirigami

    PubMed Central

    Castle, Toen; Sussman, Daniel M.; Tanis, Michael; Kamien, Randall D.

    2016-01-01

    Kirigami uses bending, folding, cutting, and pasting to create complex three-dimensional (3D) structures from a flat sheet. In the case of lattice kirigami, this cutting and rejoining introduces defects into an underlying 2D lattice in the form of points of nonzero Gaussian curvature. A set of simple rules was previously used to generate a wide variety of stepped structures; we now pare back these rules to their minimum. This allows us to describe a set of techniques that unify a wide variety of cut-and-paste actions under the rubric of lattice kirigami, including adding new material and rejoining material across arbitrary cuts in the sheet. We also explore the use of more complex lattices and the different structures that consequently arise. Regardless of the choice of lattice, creating complex structures may require multiple overlapping kirigami cuts, where subsequent cuts are not performed on a locally flat lattice. Our additive kirigami method describes such cuts, providing a simple methodology and a set of techniques to build a huge variety of complex 3D shapes. PMID:27679822

  18. Additive lattice kirigami

    PubMed Central

    Castle, Toen; Sussman, Daniel M.; Tanis, Michael; Kamien, Randall D.

    2016-01-01

    Kirigami uses bending, folding, cutting, and pasting to create complex three-dimensional (3D) structures from a flat sheet. In the case of lattice kirigami, this cutting and rejoining introduces defects into an underlying 2D lattice in the form of points of nonzero Gaussian curvature. A set of simple rules was previously used to generate a wide variety of stepped structures; we now pare back these rules to their minimum. This allows us to describe a set of techniques that unify a wide variety of cut-and-paste actions under the rubric of lattice kirigami, including adding new material and rejoining material across arbitrary cuts in the sheet. We also explore the use of more complex lattices and the different structures that consequently arise. Regardless of the choice of lattice, creating complex structures may require multiple overlapping kirigami cuts, where subsequent cuts are not performed on a locally flat lattice. Our additive kirigami method describes such cuts, providing a simple methodology and a set of techniques to build a huge variety of complex 3D shapes.

  19. Fabrication of targets to support laser-driven shockwave experiments. Progress report

    SciTech Connect

    Stein, J.D.

    1980-12-01

    Methods are being examined to fabricate and characterize precise multiple-stepped foils. Physical vapor deposition of metals onto substrates using precise masking to define each step was evaluated. A process for depositing metal onto preetched substrates to replicate precise steps is being developed.

  20. Application of CIS to high-efficiency PV module fabrication. Annual technical progress report, April 1, 1995--March 31, 1996

    SciTech Connect

    Basol, B.; Kapur, V.; Leidholm, C.; Halani, A.

    1996-06-01

    The authors investigated the interactions between the soda-lime glass substrate, the Mo contract film and the CIS absorber layer. Excessive Na diffusion through the Mo layer was found to be the reason for excessive interaction between the substrate and the CIS layers obtained by the H{sub 2}Se selenization technique. This chemical interaction influenced the stoichiometric uniformity of the absorbers. Addition of Ga into the CIS layers by the two-stage selenization technique yielded graded absorber structures with higher Ga content near the Mo/absorber interface. Gallium was later diffused through the absorber film by a high-temperature annealing step, and large bandgap alloys were obtained. Solar cells with active-area efficiencies of close to 12% were fabricated on these CIGS layers. Sulfur addition experiments were also carried out during this period. By controlling the Se and S availability to the precursors during the reaction step of the process, various S profiles were obtained in high-bandgap absorber layers. The highest-efficiency cell made on S-containing absorbers was about 10% efficient. A low-cost, non-vacuum technique was successfully developed for CIS film growth. Layers prepared using this novel approach were used for solar-cell and submodule fabrication. Solar cells with active-area efficiencies around 13% were demonstrated; submodules with efficiencies above 8% were also fabricated. These results represent the best PV devices ever produced on CIS layers obtained by a non-vacuum technique.

  1. 1992 STEP Symposium

    NASA Astrophysics Data System (ADS)

    Lui, Tony

    The year 1992 marks the quincentenary jubilee of the famous voyage of Christopher Columbus to the New World, a trip which initiated sustained contact between Europe and the American continent. Courageous explorations often lead to advancement of mankind, be they in uncharted territory or science. As much as Columbus was unaware of what lay in store for his voyage, we were just as poorly informed about what lay beyond our home planet when we began space exploration about three decades ago. There is much similarity among the pioneering spirits characteristic of both endeavors. It is thus fitting to celebrate this quincentenary occasion by declaring 1992 International Space Year (ISY).In conjunction with the COSPAR Meeting and the International Convention of the World Space Congress to be held in Washington, D.C., from August to September 1992, a 4-day symposium on the initial results from the Solar-Terrestrial Energy Program (STEP) Facilities and Theory Campaigns will be held at Johns Hopkins University, Applied Physics Laboratory, Laurel, Md., August 24-27. 1992.

  2. Directivity pattern of the sound radiated from axisymmetric stepped plates.

    PubMed

    He, Xiping; Yan, Xiuli; Li, Na

    2016-08-01

    For the purpose of optimal design and efficient utilization of the kind of stepped plate radiator in air, in this contribution, an approach for calculation of the directivity pattern of the sound radiated from a stepped plate in flexural vibration with a free edge is developed based on Kirchhoff-Love hypothesis and Rayleigh integral principle. Experimental tests of directivity pattern for a fabricated flat plate and two fabricated plates with one and two step radiators were carried out. It shows that the configuration of the measured directivity patterns by the proposed analytic approach is similar to those of the calculated approach. Comparison of the agreement between the calculated directivity pattern of a stepped plate and its corresponding theoretical piston show that the former radiator is equivalent to the latter, and the diffraction field generated by the unbaffled upper surface may be small. It also shows that the directivity pattern of a stepped radiator is independent of the metallic material but dependent on the thickness of base plate and resonant frequency. The thicker the thickness of base plate, the more directive the radiation is. The proposed analytic approach in this work may be adopted for any other plates with multi-steps.

  3. Directivity pattern of the sound radiated from axisymmetric stepped plates.

    PubMed

    He, Xiping; Yan, Xiuli; Li, Na

    2016-08-01

    For the purpose of optimal design and efficient utilization of the kind of stepped plate radiator in air, in this contribution, an approach for calculation of the directivity pattern of the sound radiated from a stepped plate in flexural vibration with a free edge is developed based on Kirchhoff-Love hypothesis and Rayleigh integral principle. Experimental tests of directivity pattern for a fabricated flat plate and two fabricated plates with one and two step radiators were carried out. It shows that the configuration of the measured directivity patterns by the proposed analytic approach is similar to those of the calculated approach. Comparison of the agreement between the calculated directivity pattern of a stepped plate and its corresponding theoretical piston show that the former radiator is equivalent to the latter, and the diffraction field generated by the unbaffled upper surface may be small. It also shows that the directivity pattern of a stepped radiator is independent of the metallic material but dependent on the thickness of base plate and resonant frequency. The thicker the thickness of base plate, the more directive the radiation is. The proposed analytic approach in this work may be adopted for any other plates with multi-steps. PMID:27586764

  4. STEPS: JPL's Astrometric Exoplanet Survey

    NASA Technical Reports Server (NTRS)

    Shaklan, Stuart; Pravdo, Steve

    2008-01-01

    Presentation topics include: STEPS ground-based astrometry at Hale Telescope; the instrument; why astronomy and why M-dwarfs; motion of center of light about center of mass in photocentric orbit; photocentric motion vs. fractional mass; high-resolution imaging of STEPS targets; GU 802 p one possible orbit plotted with data, Keplerian frame; GJ 802 results; STEPS future; and a bibliography of STEPS papers.

  5. Alternative fabrication process for edgeless detectors on 6 in. wafers

    NASA Astrophysics Data System (ADS)

    Kalliopuska, Juha; Eränen, Simo; Virolainen, Tuula

    2011-05-01

    VTT has developed a straightforward and fast process to fabricate edgeless (active edge) microstrip and pixel detectors on 6 in. (150 mm) wafers. The process avoids all slow process steps, such as polysilicon growth, planarization and additional ICP-etching. We have successfully fabricated 150 μm thick p-on-n and n-on-n prototypes of edgeless detectors having dead layers at the edge with a thickness below a micron. Fabrication was done on high resistivity n-type FZ-silicon wafers. The prototypes include 5×5 and 1×1 cm2 edgeless microstrip detectors with DC-, FOXFET- and PT-couplings. In addition 1.4×1.4 cm2 Medipix2 edgeless pixel detectors were also fabricated.This paper presents leakage current, capacitance and breakdown voltage measurements of different DC-coupled microstrip designs and compares them with respect to the active edge distance and polarity of the detector. The active edge distances were 20, 50 and 100 μm from the strips. Electrical characterization of these detectors on the wafer level gave promising results. A good uniformity in the measured parameters was observed for the inner strips. The parameters of the adjacent strip to the edge showed a dramatic dependence on the active edge distance. Leakage current and capacitance of the inner microstrips were 50-70 nA/cm2 and 580-660 pF/cm2 at, respectively, 40 V reverse bias for the p-on-n. For the n-on-n design these parameters were 116-118 nA/cm2 and 930-960 pF/cm2. The breakdown voltages were above 150 V for p-on-n prototypes and increased as a function of active edge distance. To fully deplete the p-on-n detectors required twice as much reverse bias as was needed for the n-on-n detectors, i.e. 13-28 V.

  6. Multiple stage miniature stepping motor

    DOEpatents

    Niven, William A.; Shikany, S. David; Shira, Michael L.

    1981-01-01

    A stepping motor comprising a plurality of stages which may be selectively activated to effect stepping movement of the motor, and which are mounted along a common rotor shaft to achieve considerable reduction in motor size and minimum diameter, whereby sequential activation of the stages results in successive rotor steps with direction being determined by the particular activating sequence followed.

  7. Powerlessness Reinterpreted: Reframing Step One.

    ERIC Educational Resources Information Center

    Young, Susan L.

    The 12 steps of the well-known mutual help group, Alcoholics Anonymous (AA), begin with Step One, admitting powerlessness. Although Step One has helped many problem drinkers and other addicts, its spiritual concepts have been criticized. The possibility of reconceptualizing powerlessness as empowering, not only within AA and its offshoot programs,…

  8. Optimization of Ultrasonic Fabric Cleaning

    SciTech Connect

    Hand, T.E.

    1998-05-13

    The fundamental purpose of this project was to research and develop a process that would reduce the cost and improve the environmental efficiency of the present dry-cleaning industry. This second phase of research (see report KCP-94-1006 for information gathered during the first phase) was intended to allow the optimal integration of all factors of ultrasonic fabric cleaning. For this phase, Garment Care performed an extensive literature search and gathered data from other researchers worldwide. The Garment Care-AlliedSignal team developed the requirements for a prototype cleaning tank for studies and acquired that tank and the additional equipment required to use it properly. Garment Care and AlliedSignal acquired the transducers and generators from Surftran Martin-Walter in Sterling Heights, Michigan. Amway's Kelly Haley developed the test protocol, supplied hundreds of test swatches, gathered the data on the swatches before and after the tests, assisted with the cleaning tests, and prepared the final analysis of the results. AlliedSignal personnel, in conjunction with Amway and Garment Care staff, performed all the tests. Additional planning is under way for future testing by outside research facilities. The final results indicated repeatable performance and good results for single layered fabric swatches. Swatches that were cleaned as a ''sandwich,'' that is, three or more layers.

  9. Method of freeform fabrication by selective gelation of powder suspensions

    DOEpatents

    Baskaran, Suresh; Graff, Gordon L.

    1997-01-01

    The present invention is a novel method for freeform fabrication. Specifically, the method of solid freeform fabrication has the steps of: (a) preparing a slurry by mixing powder particles with a suspension medium and a gelling polysaccharide; (b) making a layer by depositing an amount of said powder slurry in a confined region; (c) hardening a selected portion of the layer by applying a gelling agent to the selected portion; and (d) repeating steps (b) and (c) to make successive layers and forming a layered object. In many applications, it is desirable to remove unhardened material followed by heating to remove gellable polysaccharide then sintering.

  10. Method of freeform fabrication by selective gelation of powder suspensions

    DOEpatents

    Baskaran, S.; Graff, G.L.

    1997-12-09

    The present invention is a novel method for freeform fabrication. Specifically, the method of solid freeform fabrication has the steps of: (a) preparing a slurry by mixing powder particles with a suspension medium and a gelling polysaccharide; (b) making a layer by depositing an amount of said powder slurry in a confined region; (c) hardening a selected portion of the layer by applying a gelling agent to the selected portion; and (d) repeating steps (b) and (c) to make successive layers and forming a layered object. In many applications, it is desirable to remove unhardened material followed by heating to remove gellable polysaccharide then sintering. 2 figs.

  11. Ultrasonic imaging system for in-process fabric defect detection

    DOEpatents

    Sheen, Shuh-Haw; Chien, Hual-Te; Lawrence, William P.; Raptis, Apostolos C.

    1997-01-01

    An ultrasonic method and system are provided for monitoring a fabric to identify a defect. A plurality of ultrasonic transmitters generate ultrasonic waves relative to the fabric. An ultrasonic receiver means responsive to the generated ultrasonic waves from the transmitters receives ultrasonic waves coupled through the fabric and generates a signal. An integrated peak value of the generated signal is applied to a digital signal processor and is digitized. The digitized signal is processed to identify a defect in the fabric. The digitized signal processing includes a median value filtering step to filter out high frequency noise. Then a mean value and standard deviation of the median value filtered signal is calculated. The calculated mean value and standard deviation are compared with predetermined threshold values to identify a defect in the fabric.

  12. Fabrication of Hydrophobic Nanostructured Surfaces for Microfluidic Control.

    PubMed

    Morikawa, Kyojiro; Tsukahara, Takehiko

    2016-01-01

    In the field of micro- and nanofluidics, various kinds of novel devices have been developed. For such devices, not only fluidic control but also surface control of micro/nano channels is essential. Recently, fluidic control by hydrophobic nanostructured surfaces have attracted much attention. However, conventional fabrication methods of nanostructures require complicated steps, and integration of the nanostructures into micro/nano channels makes fabrication procedures even more difficult and complicated. In the present study, a simple and easy fabrication method of nanostructures integrated into microchannels was developed. Various sizes of nanostructures were successfully fabricated by changing the plasma etching time and etching with a basic solution. Furthermore, it proved possible to construct highly hydrophobic nanostructured surfaces that could effectively control the fluid in microchannels at designed pressures. We believe that the fabrication method developed here and the results obtained are valuable contributions towards further applications in the field of micro- and nanofluidics. PMID:26753710

  13. Soft-mask fabrication of gallium arsenide nanomembranes for integrated quantum photonics.

    PubMed

    Midolo, L; Pregnolato, T; Kiršanskė, G; Stobbe, S

    2015-12-01

    We report on the fabrication of quantum photonic integrated circuits based on suspended GaAs membranes. The fabrication process consists of a single lithographic step followed by inductively coupled-plasma dry etching through an electron-beam-resist mask and wet etching of a sacrificial layer. This method does not require depositing, etching, and stripping a hard mask, greatly reducing fabrication time and costs, while at the same time yielding devices of excellent structural quality. We discuss in detail the procedures for cleaning the resist residues caused by the plasma etching and present a statistical analysis of the etched feature size after each fabrication step.

  14. Soft-mask fabrication of gallium arsenide nanomembranes for integrated quantum photonics

    NASA Astrophysics Data System (ADS)

    Midolo, L.; Pregnolato, T.; Kiršanskė, G.; Stobbe, S.

    2015-12-01

    We report on the fabrication of quantum photonic integrated circuits based on suspended GaAs membranes. The fabrication process consists of a single lithographic step followed by inductively coupled-plasma dry etching through an electron-beam-resist mask and wet etching of a sacrificial layer. This method does not require depositing, etching, and stripping a hard mask, greatly reducing fabrication time and costs, while at the same time yielding devices of excellent structural quality. We discuss in detail the procedures for cleaning the resist residues caused by the plasma etching and present a statistical analysis of the etched feature size after each fabrication step.

  15. Fabrication and characterization of plasmonic nanorods with high aspect ratios

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaoxiao; Hu, Sheng; Li, Zhigang; Lv, Jiangtao; Si, Guangyuan

    2016-08-01

    Metallic nanostructures with high aspect ratios are important for developing devices in photonics and integrated optics. However, fabricating well-aligned plasmonic arrays is challenging due to the difficulties of etching metals. In this work, we investigate the feasibility of constructing high aspect ratio nanorods with desired shapes and controllable geometric parameters using direct focused ion beam etching. The whole fabrication process only involves a metal-deposition step and a single milling of designed patterns. Detailed characterizations of the fabricated devices are also experimentally demonstrated.

  16. Wide-spectrum activity of a silver-impregnated fabric.

    PubMed

    Gerba, Charles P; Sifuentes, Laura Y; Lopez, Gerardo U; Abd-Elmaksoud, Sherif; Calabrese, Jesse; Tanner, Benjamin

    2016-06-01

    Fabrics, such as clothing, drapes, pillowcases, and bedsheets are potential sources of pathogenic bacteria and viruses. We found fabrics (ie, professional clothing, pillowcases, and lab coats) treated with a silver-impregnated material to be effective in significantly reducing a wide spectrum of ordinary and drug-resistant microorganisms, including Salmonella, methicillin-resistant Staphylococcus aureus, Propionibacterium acnes, Trichphyton mentagrophytes, and norovirus. Fabrics impregnated with antimicrobial agents help provide an additional barrier to the transport or reservoir of pathogens in health care environments.

  17. High-Thermal-Conductivity Fabrics

    NASA Technical Reports Server (NTRS)

    Chibante, L. P. Felipe

    2012-01-01

    Heat management with common textiles such as nylon and spandex is hindered by the poor thermal conductivity from the skin surface to cooling surfaces. This innovation showed marked improvement in thermal conductivity of the individual fibers and tubing, as well as components assembled from them. The problem is centered on improving the heat removal of the liquid-cooled ventilation garments (LCVGs) used by astronauts. The current design uses an extensive network of water-cooling tubes that introduces bulkiness and discomfort, and increases fatigue. Range of motion and ease of movement are affected as well. The current technology is the same as developed during the Apollo program of the 1960s. Tubing material is hand-threaded through a spandex/nylon mesh layer, in a series of loops throughout the torso and limbs such that there is close, form-fitting contact with the user. Usually, there is a nylon liner layer to improve comfort. Circulating water is chilled by an external heat exchanger (sublimator). The purpose of this innovation is to produce new LCVG components with improved thermal conductivity. This was addressed using nanocomposite engineering incorporating high-thermalconductivity nanoscale fillers in the fabric and tubing components. Specifically, carbon nanotubes were added using normal processing methods such as thermoplastic melt mixing (compounding twin screw extruder) and downstream processing (fiber spinning, tubing extrusion). Fibers were produced as yarns and woven into fabric cloths. The application of isotropic nanofillers can be modeled using a modified Nielsen Model for conductive fillers in a matrix based on Einstein s viscosity model. This is a drop-in technology with no additional equipment needed. The loading is limited by the ability to maintain adequate dispersion. Undispersed materials will plug filtering screens in processing equipment. Generally, the viscosity increases were acceptable, and allowed the filled polymers to still be

  18. Strategies for the fabrication of porous platinum electrodes.

    PubMed

    Kloke, Arne; von Stetten, Felix; Zengerle, Roland; Kerzenmacher, Sven

    2011-11-16

    Porous platinum is of high technological importance due to its various applications in fuel cells, sensors, stimulation electrodes, mechanical actuators and catalysis in general. Based on a discussion of the general principles behind the reduction of platinum salts and corresponding deposition processes this article discusses techniques available for platinum electrode fabrication. The numerous, different strategies available to fabricate platinum electrodes are reviewed and discussed in the context of their tuning parameters, strengths and weaknesses. These strategies comprise bottom-up approaches as well as top-down approaches. In bottom-up approaches nanoparticles are synthesized in a fi rst step by chemical, photochemical or sonochemical means followed by an electrode formation step by e.g. thin fi lm technology or network formation to create a contiguous and conducting solid electrode structure. In top-down approaches fabrication starts with an already conductive electrode substrate. Corresponding strategies enable the fabrication of substrate-based electrodes by e.g. electrodeposition or the fabrication of self-supporting electrodes by dealloying. As a further top-down strategy, this review describes methods to decorate porous metals other than platinum with a surface layer of platinum. This way, fabrication methods not performable with platinum can be applied to the fabrication of platinum electrodes with the special benefit of low platinum consumption. PMID:22180890

  19. Prevalence of dry methods in granite countertop fabrication in Oklahoma.

    PubMed

    Phillips, Margaret L; Johnson, Andrew C

    2012-01-01

    Granite countertop fabricators are at risk of exposure to respirable crystalline silica, which may cause silicosis and other lung conditions. The purpose of this study was to estimate the prevalence of exposure control methods, especially wet methods, in granite countertop fabrication in Oklahoma to assess how many workers might be at risk of overexposure to crystalline silica in this industry. Granite fabrication shops in the three largest metropolitan areas in Oklahoma were enumerated, and 47 of the 52 shops participated in a survey on fabrication methods. Countertop shops were small businesses with average work forces of fewer than 10 employees. Ten shops (21%) reported using exclusively wet methods during all fabrication steps. Thirty-five shops (74%) employing a total of about 200 workers reported using dry methods all or most of the time in at least one fabrication step. The tasks most often performed dry were edge profiling (17% of shops), cutting of grooves for reinforcing rods (62% of shops), and cutting of sink openings (45% of shops). All shops reported providing either half-face or full-face respirators for use during fabrication, but none reported doing respirator fit testing. Few shops reported using any kind of dust collection system. These findings suggest that current consumer demand for granite countertops is giving rise to a new wave of workers at risk of silicosis due to potential overexposure to granite dust.

  20. Microfluidic channel fabrication method

    DOEpatents

    Arnold, Don W.; Schoeniger, Joseph S.; Cardinale, Gregory F.

    2001-01-01

    A new channel structure for microfluidic systems and process for fabricating this structure. In contrast to the conventional practice of fabricating fluid channels as trenches or grooves in a substrate, fluid channels are fabricated as thin walled raised structures on a substrate. Microfluidic devices produced in accordance with the invention are a hybrid assembly generally consisting of three layers: 1) a substrate that can or cannot be an electrical insulator; 2) a middle layer, that is an electrically conducting material and preferably silicon, forms the channel walls whose height defines the channel height, joined to and extending from the substrate; and 3) a top layer, joined to the top of the channels, that forms a cover for the channels. The channels can be defined by photolithographic techniques and are produced by etching away the material around the channel walls.

  1. Fabric filter system study

    NASA Astrophysics Data System (ADS)

    Chambers, R. L.; Plunk, O. C.; Kunka, S. L.

    1984-08-01

    Results of the fourth year of operation of a fabric filter installed on a coal-fired boiler are reported. Project work during the fourth year concentrated on fabric studies. The 10-oz/sq yd fabrics of the 150 1/2 warp, 150 2/2T fill construction demonstrated superior performance over the most common 14-oz/sq yd constructions, regardless of coating. It was determined that improving cleaning by increasing shaking amplitude is more detrimental to baglife than increasing shaker frequency. Maintenance and operation observations continued, and the resolution of these types of problems became more efficient because of increased experience of maintenance personnel with baghouse-related problems.

  2. Experimental Investigation of Air-Cooled Turbine Blades in Turbojet Engine. 7: Rotor-Blade Fabrication Procedures

    NASA Technical Reports Server (NTRS)

    Long, Roger A.; Esgar, Jack B.

    1951-01-01

    An experimental investigation was conducted to determine the cooling effectiveness of a wide variety of air-cooled turbine-blade configurations. The blades, which were tested in the turbine of a - commercial turbojet engine that was modified for this investigation by replacing two of the original blades with air-cooled blades located diametrically opposite each other, are untwisted, have no aerodynamic taper, and have essentially the same external profile. The cooling-passage configuration is different for each blade, however. The fabrication procedures were varied and often unique. The blades were fabricated using methods most suitable for obtaining a small number of blades for use in the cooling investigations and therefore not all the fabrication procedures would be directly applicable to production processes, although some of the ideas and steps might be useful. Blade shells were obtained by both casting and forming. The cast shells were either welded to the blade base or cast integrally with the base. The formed shells were attached to the base by a brazing and two welding methods. Additional surface area was supplied in the coolant passages by the addition of fins or tubes that were S-brazed. to the shell. A number of blades with special leading- and trailing-edge designs that provided added cooling to these areas were fabricated. The cooling effectiveness and purposes of the various blade configurations are discussed briefly.

  3. Magnetostrictive Roller-Drive Stepping Motor

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1993-01-01

    Proposed motor based on magnetostrictive effect provides stepped angular motion with angular increments of order of 100 microradians. Driven to repeat stepping cycle rapidly enough to achieve maximum speed of about 20 rpm, provides torque an order of magnitude greater than electric motors, and brakes itself when power turned off. Magnetostrictive rods in electromagnet coils push against drive plate, causing it to rotate slightly. This slight rotation jams conical rollers between cam surfaces on outer drive ring and split drum, so rollers transmit rotation to drum. Suitable for precise, high-torque, fail-safe-braking, direct drive of robot joint, without bulk and weight of additional brake mechanism and gear train.

  4. In Situ Fabrication Technologies

    NASA Technical Reports Server (NTRS)

    Rolin, Terry D.; Hammond, Monica

    2005-01-01

    A manufacturing system is described that is internal to controlled cabin environments which will produce functional parts to net shape with sufficient tolerance, strength and integrity to meet application specific needs such as CEV ECLS components, robotic arm or rover components, EVA suit items, unforeseen tools, conformal repair patches, and habitat fittings among others. Except for start-up and shut-down, fabrication will be automatic without crew intervention under nominal scenarios. Off-nominal scenarios may require crew and/or Earth control intervention. System will have the ability to fabricate using both provisioned feedstock materials and feedstock refined from in situ regolith.

  5. Thermal Skin fabrication technology

    NASA Technical Reports Server (NTRS)

    Milam, T. B.

    1972-01-01

    Advanced fabrication techniques applicable to Thermal Skin structures were investigated, including: (1) chemical machining; (2) braze bonding; (3) diffusion bonding; and (4) electron beam welding. Materials investigated were nickel and nickel alloys. Sample Thermal Skin panels were manufactured using the advanced fabrication techniques studied and were structurally tested. Results of the program included: (1) development of improved chemical machining processes for nickel and several nickel alloys; (2) identification of design geometry limits; (3) identification of diffusion bonding requirements; (4) development of a unique diffusion bonding tool; (5) identification of electron beam welding limits; and (6) identification of structural properties of Thermal Skin material.

  6. Other Fabric Structures

    NASA Technical Reports Server (NTRS)

    1985-01-01

    There are two kinds of fabric structures - tension, supported by cables and pylons, and those supported by air pressure within an enclosed fabric envelope. They are becoming increasingly popular with architects, engineers, etc., because of their aesthetic appeal, low cost and maintenance, energy efficiency and good space utilization. The Structo-Fab roof weighs only 1/30 as much as a conventional roof of that size. Giant fans are used to blow air into the envelope between the roof's outer membrane and its inner liner automatically maintaining the pressure differential necessary for roof rigidity.

  7. Fabrication of multilayer nanowires

    NASA Astrophysics Data System (ADS)

    Kaur, Jasveer; Singh, Avtar; Kumar, Davinder; Thakur, Anup; Kaur, Raminder

    2016-05-01

    Multilayer nanowires were fabricated by potentiostate ectrodeposition template synthesis method into the pores of polycarbonate membrane. In present work layer by layer deposition of two different metals Ni and Cu in polycarbonate membrane having pore size of 600 nm were carried out. It is found that the growth of nanowires is not constant, it varies with deposition time. Scanning electron microscopy (SEM) is used to study the morphology of fabricated multilayer nanowires. An energy dispersive X-ray spectroscopy (EDS) results confirm the composition of multilayer nanowires. The result shows that multilayer nanowires formed is dense.

  8. Modifications of Fabrication of Vibratory Microgyroscopes

    NASA Technical Reports Server (NTRS)

    Bae, Sam Y.; Yee, Karl Y.; Wiberg, Dean

    2005-01-01

    A micromachining process for the fabrication of vibratory microgyroscopes from silicon wafers, and aspects of the microgyroscope design that are inextricably linked with the fabrication process, have been modified in an effort to increase production yields from perspectives of both quantity and quality. Prior to the modifications, the effective production yield of working microgyroscopes was limited to one or less per wafer. The modifications are part of a continuing effort to improve the design and increase production yields to more than 30 working microgyroscopes per wafer. A discussion of pertinent aspects of the unmodified design and the unmodified fabrication process is prerequisite to a meaningful description of the modifications. The design of the microgyroscope package was not conducive to high yield and rapid testing of many microgyroscopes. One of the major impediments to high yield and testing was found to lie in vibration- isolation beams around the four edges of each microgyroscope, which beams were found to be unnecessary for achieving high resonance quality factors (Q values) characterizing the vibrations of petallike cantilevers. The fabrication process included an 8- m-deep plasma etch. The purpose of the etch was to create 8- m vertical gaps, below which were to be placed large gold evaporated electrodes and sensing pads to drive and sense resonant vibrations of the "petals." The process also included a step in which bridges between dies were cut to separate the dies. The etched areas must be kept clean and smooth (free of debris and spikes), because any object close to 8 m high in those areas would stop the vibrations. However, it was found that after the etch, there remained some spikes with heights that were, variously, almost as high or as high as the etch depth. It also was found that the cutting of bridges created silicon debris, some of which lodged in the 8- m gaps and some of which landed on top of the petals. The masses added to the

  9. Electronic textiles: A logical step

    NASA Astrophysics Data System (ADS)

    de Rossi, Danilo

    2007-05-01

    The integration of electronics and clothing promises a variety of new technologies, but constructing electronic circuits on fabrics is complex. Coating fibres to create electrodes and forming transistors at their crossing points offers an elegant solution.

  10. Fabrication of a polymer-metal combined atomic force microscopy probe for coarse food surface imaging.

    PubMed

    Kang, Hyen-Wook; Muramatsu, Hiroshi; Kwon, Young-Soo

    2013-05-01

    We fabricated a polymer-metal combined atomic force microscopy (AFM) probe by two steps; a polymeric resin was used at first step, and a metal-ion was used at second step which needs more fabricating time than the resin. At first step, we fabricated a cylindrical base on to a commercial cantilever. At second step, we fabricated a conical probe on to the fabricated cylindrical base. To make the conical probe composed with silver, a 0.2 M aqueous solution of silver nitrate (AgNO3) was used. A 50 microm length polymeric-metallic hybrid tip has been fabricated to observe large bio and food samples. Generally, the AFM images of bio/food samples show cliff-like sharp patters in vertical. However, the AFM image by fabricated long tip shows clear structure of each brown rice flours. As most of commercial tips have three-angular pyramidal, the scanned results should be influenced by the lateral face of the three-angular pyramid, which results in cliff-like images. Because the sample size is large, the side area of the sample was adversely affected by the pyramidal structure during imaging. This problem may be resolved by designing conical structure tips. As the conical structure has no edge, the AFM image becomes clear. The fabricated tip has conical structure, and a clear AFM image was achieved. PMID:23858900

  11. Effect of Fabric Cover and Pore Area Distribution of Carbon/Stainless Steel/Polypropylene Hybrid Yarn-Woven Fabric on Electromagnetic Shielding Effectiveness

    NASA Astrophysics Data System (ADS)

    Krishnasamy, Jagatheesan; Ramasamy, Alagirusamy; Das, Apurba; Basu, Ananjan

    2016-06-01

    The electromagnetic shielding behavior of fabrics woven with carbon/stainless steel/polypropylene (C/SS/PP) hybrid yarns were investigated in the frequency range of 300 kHz to 1.5 GHz. This study mainly emphasizes the electromagnetic shielding behavior of C/SS/PP hybrid yarn fabric and the effect of different fabric parameters such as pick density, fabric architecture and number of fabric layers on shielding effectiveness (SE) of fabrics with C/SS/PP hybrid yarns. The SE of fabric samples were tested by a vector network analyzer using a coaxial transmission line tester. In addition, surface images of different fabric structures were examined to appreciate the effect of yarn floats on the shielding behavior of fabrics. From the SE test, it was observed that an increase in pick density increases the SE of C/SS/PP hybrid yarn fabric due to addition of carbon and SS content in the fabric. Besides, the fabric cover and pore area distribution are also changed for varying pick densities. Essentially, a fabric's architecture plays an important role in the fabric cover and pore area distribution. The one-end float (1/1 plain) fabric of 6.3 ppcm provides higher shielding of 88.44 dB than a 4-end (4/1 twill) or 7-end float (8-end satin) fabrics of 6.3 ppcm. Moreover, an increase in the number of fabric layers also improves the SE of fabrics. The developed C/SS/PP hybrid yarn fabric can be used for shielding wireless transmissions, radar transmissions and for shielding panels.

  12. Low cost fabrication of ablative heat shields

    NASA Technical Reports Server (NTRS)

    Cecka, A. M.; Schofield, W. C.

    1972-01-01

    A material and process study was performed using subscale panels in an attempt to reduce the cost of fabricating ablative heat shield panels. Although no improvements were made in the material formulation, a significant improvement was obtained in the processing methods compared to those employed in the previous work. The principal feature of the new method is the press filling and curing of the ablation material in a single step with the bonding and curing of the face sheet. This method was chosen to replace the hand troweling and autoclave curing procedure used previously. Double-curvature panels of the same size as the flat panels were fabricated to investigate fabrication problems. It was determined that the same materials and processes used for flat panels can be used to produce the curved panels. A design with severe curvatures consisting of radii of 24 x 48 inches was employed for evaluation. Ten low-density and ten high-density panels were fabricated. With the exception of difficulties related to short run non-optimum tooling, excellent panel filling and density uniformity were obtained.

  13. Lithographic fabrication of nanoapertures

    DOEpatents

    Fleming, James G.

    2003-01-01

    A new class of silicon-based lithographically defined nanoapertures and processes for their fabrication using conventional silicon microprocessing technology have been invented. The new ability to create and control such structures should significantly extend our ability to design and implement chemically selective devices and processes.

  14. Particle Swarm Optimization with Dynamic Step Length

    NASA Astrophysics Data System (ADS)

    Cui, Zhihua; Cai, Xingjuan; Zeng, Jianchao; Sun, Guoji

    Particle swarm optimization (PSO) is a robust swarm intelligent technique inspired from birds flocking and fish schooling. Though many effective improvements have been proposed, however, the premature convergence is still its main problem. Because each particle's movement is a continuous process and can be modelled with differential equation groups, a new variant, particle swarm optimization with dynamic step length (PSO-DSL), with additional control coefficient- step length, is introduced. Then the absolute stability theory is introduced to analyze the stability character of the standard PSO, the theoretical result indicates the PSO with constant step length can not always be stable, this may be one of the reason for premature convergence. Simulation results show the PSO-DSL is effective.

  15. A facile fabrication of multifunctional knit polyester fabric based on chitosan and polyaniline polymer nanocomposite

    NASA Astrophysics Data System (ADS)

    Tang, Xiaoning; Tian, Mingwei; Qu, Lijun; Zhu, Shifeng; Guo, Xiaoqing; Han, Guangting; Sun, Kaikai; Hu, Xili; Wang, Yujiao; Xu, Xiaoqi

    2014-10-01

    Knit polyester fabric was successively modified and decorated with chitosan layer and polyaniline polymer nanocomposite layer in this paper. The fabric was firstly treated with chitosan to form a stable layer through the pad-dry-cure process, and then the polyaniline polymer nanocomposite layer was established on the outer layer by in situ chemical polymerization method using ammonium persulfate as oxidant and chlorhydric acid as dopant. The surface morphology of coated fabric was characterized by scanning electron microscopy (SEM), and the co-existence of chitosan layer and granular polyaniline polymer nanocomposite was confirmed and well dispersed on the fabric surface. The resultant fabric was endowed with remarkable electrical conductivity properties and efficient water-repellent capability, which also have been found stable after water laundering. In addition, the photocatalytic decomposition activity for reactive red dye was observed when the multifunctional knit polyester fabric was exposed to the illumination of ultraviolet lamp. These results indicated that chitosan and polyaniline polymer nanocomposite could form ideal multifunctional coatings on the surface of knit polyester fabric.

  16. Fabricating PFPE Membranes for Capillary Electrophoresis

    NASA Technical Reports Server (NTRS)

    Lee, Michael C.; Willis, Peter A.; Greer, Frank; Rolland, Jason

    2009-01-01

    A process has been developed for fabricating perfluoropolyether (PFPE) membranes that contain microscopic holes of precise sizes at precise locations. The membranes are to be incorporated into laboratory-on-a-chip microfluidic devices to be used in performing capillary electrophoresis. The present process is a modified version of part of the process, described in the immediately preceding article, that includes a step in which a liquid PFPE layer is cured into solid (membrane) form by use of ultraviolet light. In the present process, one exploits the fact that by masking some locations to prevent exposure to ultraviolet light, one can prevent curing of the PFPE in those locations. The uncured PFPE can be washed away from those locations in the subsequent release and cleaning steps. Thus, holes are formed in the membrane in those locations. The most straightforward way to implement the modification is to use, during the ultraviolet-curing step, an ultraviolet photomask similar to the photomasks used in fabricating microelectronic devices. In lieu of such a photomask, one could use a mask made of any patternable ultraviolet-absorbing material (for example, an ink or a photoresist).

  17. Dyeing fabrics with metals

    NASA Astrophysics Data System (ADS)

    Kalivas, Georgia

    2002-06-01

    Traditionally, in textile dyeing, metals have been used as mordants or to improve the color produced by a natural or synthetic dye. In biomedical research and clinical diagnostics gold colloids are used as sensitive signals to detect the presence of pathogens. It has been observed that when metals are finely divided, a distinct color may result that is different from the color of the metal in bulk. For example, when gold is finely divided it may appear black, ruby or purple. This can be seen in biomedical research when gold colloids are reduced to micro-particles. Bright color signals are produced by few nanometer-sized particles. Dr. William Todd, a researcher in the Department of Veterinary Science at the Louisiana State University, developed a method of dyeing fabrics with metals. By using a reagent to bond the metal particles deep into the textile fibers and actually making the metal a part of the chemistry of the fiber. The chemicals of the fabric influence the resulting color. The combination of the element itself, the size of the particle, the chemical nature of the particle and the interaction of the metal with the chemistry of the fabric determine the actual hue. By using different elements, reagents, textiles and solvents a broad range of reproducible colors and tones can be created. Metals can also be combined into alloys, which will produce a variety of colors. The students of the ISCC chapter at the Fashion Institute of Technology dyed fabric using Dr. Todd's method and created a presentation of the results. They also did a demonstration of dyeing fabrics with metals.

  18. Energy-beam-driven rapid fabrication system

    DOEpatents

    Keicher, David M.; Atwood, Clinton L.; Greene, Donald L.; Griffith, Michelle L.; Harwell, Lane D.; Jeantette, Francisco P.; Romero, Joseph A.; Schanwald, Lee P.; Schmale, David T.

    2002-01-01

    An energy beam driven rapid fabrication system, in which an energy beam strikes a growth surface to form a molten puddle thereon. Feed powder is then injected into the molten puddle from a converging flow of feed powder. A portion of the feed powder becomes incorporated into the molten puddle, forcing some of the puddle contents to freeze on the growth surface, thereby adding an additional layer of material. By scanning the energy beam and the converging flow of feed powder across the growth surface, complex three-dimensional shapes can be formed, ready or nearly ready for use. Nearly any class of material can be fabricated using this system.

  19. Silicon nanowire growth and transistor fabrication by self-assembling "grow-in-place" approach

    NASA Astrophysics Data System (ADS)

    Shan, Yinghui

    Nanowires have attracted much attention recently owing to their ability to serve as critical building blocks for emerging nanotechnologies. Silicon nanowires (SiNWs) are particularly promising because of the central role of silicon in semiconductor industry. SiNWs would allow device fabrication with high density and their high surface to volume ratio offers high sensitivity. In addition, the possible quantum confinement in SiNWs may further enhance device performances and open windows for exploiting fundamental properties. Intense researches have been carried out in SiNW growth and device fabrication. However, there are still challenges in SiNW growth controls, such as size, number, shape, position, orientation, and inter-wire spacings. To make devices from these SiNWs, post-growth processing steps are needed, such as SiNW collecting, picking, positioning, aligning, and assembling. Due to the extremely small size of SiNWs, there are also challenges in SiNW device fabrication. To solve these challenges in both SiNW growth control and device fabrication, we introduced a novel self-assembling "grow-in-place" approach. Our approach combined vapor-liquid-solid (VLS) nanowire growth mechanism and pre-fabricated nanochannel template. The VLS growth mechanism offers the ability of controlling nanowire size and shape by nanochannel templates. The pre-fabricated nanochannel template guides nanowire growth and offers good SiNW growth control. SiNWs and silicon nanoribbons (SiNRs) with different sizes have been successfully grown in our nanochannel templates. Characterizations on their size, shape, composition, and crystallinity of the SiNW/Rs have confirmed that our "grow-in-place" approach offers good controls on crystalline SiNW/Rs size, shape, number, orientation, position, and inter-wire spacing. So our approach solved the challenges in SiNW growth control. Our grow-in-place approach also solved the challenges in SiNW device fabrication. We introduced two versions of

  20. Fabrication of detectors and transistors on high-resistivity silicon

    SciTech Connect

    Holland, S.

    1988-06-01

    A new process for the fabrication of silicon p-i-n diode radiation detectors is described. The utilization of backside gettering in the fabrication process results in the actual physical removal of detrimental impurities from critical device regions. This reduces the sensitivity of detector properties to processing variables while yielding low diode reverse-leakage currents. In addition, gettering permits the use of processing temperatures compatible with integrated-circuit fabrication. P-channel MOSFETs and silicon p-i-n diodes have been fabricated simultaneously on 10 k..cap omega../center dot/cm<100> silicon using conventional integrated-circuit processing techniques. 25 refs., 5 figs.

  1. Acoustofluidic actuation of in situ fabricated microrotors.

    PubMed

    Kaynak, Murat; Ozcelik, Adem; Nama, Nitesh; Nourhani, Amir; Lammert, Paul E; Crespi, Vincent H; Huang, Tony Jun

    2016-09-21

    We have demonstrated in situ fabricated and acoustically actuated microrotors. A polymeric microrotor with predefined oscillating sharp-edge structures is fabricated in situ by applying a patterned UV light to polymerize a photocrosslinkable polyethylene glycol solution inside a microchannel around a polydimethylsiloxane axle. To actuate the microrotors by oscillating the sharp-edge structures, we employed piezoelectric transducers which generate tunable acoustic waves. The resulting acoustic streaming flows rotate the microrotors. The rotation rate is tuned by controlling the peak-to-peak voltage applied to the transducer. A 6-arm microrotor can exceed 1200 revolutions per minute. Our technique is an integration of single-step microfabrication, instant assembly around the axle, and easy acoustic actuation for various applications in microfluidics and microelectromechanical systems (MEMS). PMID:27466140

  2. High precision fabrication of antennas and sensors

    NASA Astrophysics Data System (ADS)

    Balčytis, A.; Seniutinas, G.; Urbonas, D.; Gabalis, M.; Vaškevičius, K.; Petruškevičius, R.; Molis, G.; Valušis, G. `.; Juodkazis, S.

    2015-02-01

    Electron and ion beam lithographies were used to fabricate and/or functionalize large scale - millimetre footprint - micro-optical elements: coupled waveguide-resonator structures on silicon-on-insulator (SOI) and THz antennas on low temperature grown LT-GaAs. Waveguide elements on SOI were made without stitching errors using a fixed beam moving stage approach. THz antennas were created using a three-step litography process. First, gold THz antennas defined by standard mask projection lithography were annealed to make an ohmic contact on LT-GaAs and post-processing with Ga-ion beam was used to define nano-gaps and inter digitised contacts for better charge collection. These approaches show the possibility to fabricate large footprint patterns with nanoscale precision features and overlay accuracy. Emerging 3D nanofabrication trends are discussed.

  3. SEM and TEM Characterization of As-Fabricated U-7Mo Disperson Fuel Plates

    SciTech Connect

    D. D. Keiser, Jr.; B. Yao; E. Perez; Y. H. Sohn

    2009-11-01

    The starting microstructure of a dispersion fuel plate can have a dramatic impact on the overall performance of the plate during irradiation. To improve the understanding of the as-fabricated microstructures of dispersion fuel plates, SEM and TEM analysis have been performed on RERTR-9A archive fuel plates, which went through an additional hot isostatic procsssing (HIP) step during fabrication. The fuel plates had depleted U-7Mo fuel particles dispersed in either Al-2Si or 4043 Al alloy matrix. For the characterized samples, it was observed that a large fraction of the ?-phase U-7Mo alloy particles had decomposed during fabrication, and in areas near the fuel/matrix interface where the transformation products were present significant fuel/matrix interaction had occurred. Relatively thin Si-rich interaction layers were also observed around the U-7Mo particles. In the thick interaction layers, (U)(Al,Si)3 and U6Mo4Al43 were identified, and in the thin interaction layers U(Al,Si)3, U3Si3Al2, U3Si5, and USi1.88-type phases were observed. The U3Si3Al2 phase contained some Mo. Based on the results of this work, exposure of dispersion fuel plates to relatively high temperatures during fabrication impacts the overall microstructure, particularly the nature of the interaction layers around the fuel particles. The time and temperature of fabrication should be carefully controlled in order to produce the most uniform Si-rich layers around the U-7Mo particles.

  4. FABRICATION PROCESS AND PRODUCT QUALITY IMPROVEMENTS IN ADVANCED GAS REACTOR UCO KERNELS

    SciTech Connect

    Charles M Barnes

    2008-09-01

    A major element of the Advanced Gas Reactor (AGR) program is developing fuel fabrication processes to produce high quality uranium-containing kernels, TRISO-coated particles and fuel compacts needed for planned irradiation tests. The goals of the AGR program also include developing the fabrication technology to mass produce this fuel at low cost. Kernels for the first AGR test (“AGR-1) consisted of uranium oxycarbide (UCO) microspheres that werre produced by an internal gelation process followed by high temperature steps tot convert the UO3 + C “green” microspheres to first UO2 + C and then UO2 + UCx. The high temperature steps also densified the kernels. Babcock and Wilcox (B&W) fabricated UCO kernels for the AGR-1 irradiation experiment, which went into the Advance Test Reactor (ATR) at Idaho National Laboratory in December 2006. An evaluation of the kernel process following AGR-1 kernel production led to several recommendations to improve the fabrication process. These recommendations included testing alternative methods of dispersing carbon during broth preparation, evaluating the method of broth mixing, optimizing the broth chemistry, optimizing sintering conditions, and demonstrating fabrication of larger diameter UCO kernels needed for the second AGR irradiation test. Based on these recommendations and requirements, a test program was defined and performed. Certain portions of the test program were performed by Oak Ridge National Laboratory (ORNL), while tests at larger scale were performed by B&W. The tests at B&W have demonstrated improvements in both kernel properties and process operation. Changes in the form of carbon black used and the method of mixing the carbon prior to forming kernels led to improvements in the phase distribution in the sintered kernels, greater consistency in kernel properties, a reduction in forming run time, and simplifications to the forming process. Process parameter variation tests in both forming and sintering steps led

  5. A two-step route to planar perovskite cells exhibiting reduced hysteresis

    SciTech Connect

    Ip, Alexander H.; Adachi, Michael M.; McDowell, Jeffrey J.; Xu, Jixian; Sargent, Edward H.; Quan, Li Na; Kim, Dong Ha

    2015-04-06

    A simple two-step method was used to produce efficient planar organolead halide perovskite solar cells. Films produced using solely iodine containing precursors resulted in poor morphology and failed devices, whereas addition of chlorine to the process greatly improved morphology and resulted in dense, uniform perovskite films. This process was used to produce perovskite solar cells with a fullerene-based passivation layer. The hysteresis effect, to which planar perovskite devices are otherwise prone, was greatly suppressed through the use of this interface modifier. The combined techniques resulted in perovskite solar cells having a stable efficiency exceeding 11%. This straightforward fabrication procedure holds promise in development of various optoelectronic applications of planar perovskite films.

  6. Leading Change Step-by-Step: Tactics, Tools, and Tales

    ERIC Educational Resources Information Center

    Spiro, Jody

    2010-01-01

    "Leading Change Step-by-Step" offers a comprehensive and tactical guide for change leaders. Spiro's approach has been field-tested for more than a decade and proven effective in a wide variety of public sector organizations including K-12 schools, universities, international agencies and non-profits. The book is filled with proven tactics for…

  7. Step by Step to Smoke-Free Schools.

    ERIC Educational Resources Information Center

    VanSciver, James H.; Roberts, H. Earl

    1989-01-01

    This ERIC digest discusses ways of effectively banning smoking in schools so that controversies do not continue after implementation of the policy. By advocating a process approach, the document cites steps taken by the Lake Forest School Board to prohibit smoking in and around school grounds. Step one involved committee planning involving…

  8. Step-By-Step Professional Development in Technology

    ERIC Educational Resources Information Center

    Meltzer, Sarah T.

    2012-01-01

    Don't train your teachers in instructional technology without reading this resource-packed book from Sarah T. Meltzer. Meltzer presents easy-to-follow guidelines for bringing about effective professional development in technology from start to finish. She takes you step-by-step through the process of planning, implementing, and managing…

  9. Fabrication of Stainless Steel Mold Using Electrochemical Fabrication Method for Microfluidic Biochip

    NASA Astrophysics Data System (ADS)

    Cho, Min-Soo; Lim, Hyun-Woo; Sunyong Lee, Caroline; Cho, Byung-Ki; Park, Jin-Goo

    2008-06-01

    Imprinting method mechanically transfers patterns from a stamp onto a substrate. In imprinting process, the mold is one of the most important factors. A new micro fabrication method termed electrochemical fabrication (ECF) is introduced to overcome conventional problems of electrical discharge machining (EDM), FeCl3 Wet etching, laser method, electro plating, such as low reliability and reproducibility, high cost. This ECF method defines micro patterns using a conventional photolithography, allowing it to produce micro-scale patterns with an excellent surface roughness and of excellent quality. In this paper, a 150 mm stainless steel (SUS 304, 5 mm in thickness) mold was fabricated using both ECF method and FeCl3-etchant method, respectively. As a result, the ECF mold resulted 10 times better surface roughness values than that of mold using FeCl3 etchant. Also, metal surface of the ECF-SUS mold was cleaner and smoother than that the FeCl3 etched SUS mold. Therefore, SUS mold was successfully fabricated for the first time in micro-scale and multi-step patterns. Plastic replica was fabricated successfully using the ECF-SUS mold.

  10. Fabrication of large thick panels of transparent spinel

    NASA Astrophysics Data System (ADS)

    Patterson, Mark; Gilde, Gary A.; Roy, Donald W.

    2001-11-01

    The use of magnesium aluminate spinel for optical windows, domes and armor has previously been investigated for a wide range of specific applications. The material properties rival that of ALON and sapphire, although there exists the potential for the fabrication of larger parts at significantly lower costs. The ability to fabricate transparent spinel by hot-pressing into large plates has gained interest for the fabrication of low-cost transparent armor for a range of applications. The present paper describes development efforts that are underway to fabricate spinel panels up to 22 inches in diameter and 0.5 inches thick. A 600 ton press is being installed at a facility in Millersville, MD that will be able to fabricate 22 inch diameter parts by late 2002. In the future, this press will potentially be able to fabricate 40 inch diameter plates with minimal changes. There is additional interest in these plates for large IR windows.

  11. Metallic parts fabrication using the SIS process

    NASA Astrophysics Data System (ADS)

    Mojdeh, Mehdi

    Since early 1980s, quite a few techniques of Rapid Prototyping (RP), also known as Layered Manufacturing, have been developed. By building three-dimensional parts in a layer-by-layer additive manner, these techniques allow freeform fabrication of parts of complex geometry. Despite recent advances in fabrication of polymer parts, most of the existing rapid prototyping processes are still not capable of fabrication of accurate metallic parts with acceptable mechanical properties. Insufficient dimensional accuracy, limited number of materials, proper mechanical properties, required post machining and lack of repeatability between builds have greatly limited the market penetration of these techniques. This dissertation presents an innovative layered manufacturing technique for fabrication of dense metallic parts called Selective Inhibition Sintering (SIS), developed at the University of Southern California. The SIS-Metal technology adapts RP capabilities and extends them to the field of fabrication of metallic parts for a variety of applications such as tooling and low volume production. Using this process, a metallic part, with varying 3 dimensional geometries, can be automatically constructed from a wide range of materials. SIS-Metal is the only RP process which is suitable for fabrication of dense, complex shaped, accurate objects using a variety of materials. In the SIS-Metal process a metallic part is built layer by layer by deposition for each layer of an inhibitor material which defines the corresponding layer boundary and then filling the voids of the created geometry with metal powder; and compacting the layer formed to reach a high powder density. The resulting green part is then sintered in a furnace to yield the final functional part. In this research different inhibition techniques were explored and a series of single and multi layer parts was fabricated using the most promising inhibition technique, namely, macro-mechanical inhibition. Dimensional

  12. Volume Diffusion Growth Kinetics and Step Geometry in Crystal Growth

    NASA Technical Reports Server (NTRS)

    Mazuruk, Konstantin; Ramachandran, Narayanan

    1998-01-01

    The role of step geometry in two-dimensional stationary volume diff4sion process used in crystal growth kinetics models is investigated. Three different interface shapes: a) a planar interface, b) an equidistant hemispherical bumps train tAx interface, and c) a train of right angled steps, are used in this comparative study. The ratio of the super-saturation to the diffusive flux at the step position is used as a control parameter. The value of this parameter can vary as much as 50% for different geometries. An approximate analytical formula is derived for the right angled steps geometry. In addition to the kinetic models, this formula can be utilized in macrostep growth models. Finally, numerical modeling of the diffusive and convective transport for equidistant steps is conducted. In particular, the role of fluid flow resulting from the advancement of steps and its contribution to the transport of species to the steps is investigated.

  13. Process for fabrication of large titanium diboride ceramic bodies

    DOEpatents

    Moorhead, Arthur J.; Bomar, E. S.; Becher, Paul F.

    1989-01-01

    A process for manufacturing large, fully dense, high purity TiB.sub.2 articles by pressing powders with a sintering aid at relatively low temperatures to reduce grain growth. The process requires stringent temperature and pressure applications in the hot-pressing step to ensure maximum removal of sintering aid and to avoid damage to the fabricated article or the die.

  14. Thin film solar cell configuration and fabrication method

    DOEpatents

    Menezes, Shalini

    2009-07-14

    A new photovoltaic device configuration based on an n-copper indium selenide absorber and a p-type window is disclosed. A fabrication method to produce this device on flexible or rigid substrates is described that reduces the number of cell components, avoids hazardous materials, simplifies the process steps and hence the costs for high volume solar cell manufacturing.

  15. Additive manufacturing of biologically-inspired materials.

    PubMed

    Studart, André R

    2016-01-21

    Additive manufacturing (AM) technologies offer an attractive pathway towards the fabrication of functional materials featuring complex heterogeneous architectures inspired by biological systems. In this paper, recent research on the use of AM approaches to program the local chemical composition, structure and properties of biologically-inspired materials is reviewed. A variety of structural motifs found in biological composites have been successfully emulated in synthetic systems using inkjet-based, direct-writing, stereolithography and slip casting technologies. The replication in synthetic systems of design principles underlying such structural motifs has enabled the fabrication of lightweight cellular materials, strong and tough composites, soft robots and autonomously shaping structures with unprecedented properties and functionalities. Pushing the current limits of AM technologies in future research should bring us closer to the manufacturing capabilities of living organisms, opening the way for the digital fabrication of advanced materials with superior performance, lower environmental impact and new functionalities.

  16. Thermoelectric material characterization and module fabrication

    NASA Astrophysics Data System (ADS)

    D'Angelo, Jonathan James

    Thermoelectric generators operate with no moving parts to convert heat flow to electricity. Significant interest in developing new materials in recent years has led to the discovery of several promising thermoelectrics; however there can be considerable challenges in developing the materials into working devices. Testing and feedback is needed at each step to gain valuable information for identification of difficulties in; quality of the materials and modules, electrical contacts to the materials, repeatability in fabrication, and longevity of the devices. The goal of this dissertation is to show results in all of these categories.

  17. Two-photon induced fabrication of gold microstructures in polystyrene sulfonate thin films using a ruthenium(II) dye as photoinitiator

    SciTech Connect

    Vurth, Laeticia; Baldeck, Patrice; Stephan, Olivier; Vitrant, Guy

    2008-04-28

    Gold microstructures are produced with a femtosecond laser in thin films of a polystyrene sulfonate matrix containing gold ions. Two-photon induced metal reduction is obtained by addition of 0.1 wt % of ruthenium(II)tris(bipyridine) in the formulation. Laser power is reduced to 5 mW, thereby limiting thermal effects. Lines of typically 150 nm heights and 1 {mu}m widths are fabricated as well as freestanding bidimensional structures. An additional electroless plating step produces gold structures with conductivities only ten times smaller than the bulk metal.

  18. Mapping of Rock-Fabric Inhomogeneity (Map-Counting) and Mapping of Rock-Fabric Anisotropy (MORFA) - the Piquiri Syenite Massif, Southern Brazil

    NASA Astrophysics Data System (ADS)

    Peternell, M.; Bitencourt, M.; Kruhl, J. H.

    2007-12-01

    During the last decade, studies on magmatic fabrics on different scale have been made for analyzing kinematics of melt emplacement and deformation as well as cooling histories of magmatic bodies and their host rocks (Brown 2001). The problem arises for comparing data from structural analysis in thin-sections and fabrics in outcrop scale. Magmatic fabrics in the outcrop scale are often very diffusely developed or show very complex mineral distribution patterns which are mostly not quantifiable with classical field methods. On the other hand the fabrics are too large for thin section investigation. Therefore, methods have to be developed for analyzing microscale rock fabrics like crystal shape preferred orientations on larger image templates, like from outcrop photographs. For analyzing such complex fabrics on different scale, methods of fractal geometry are powerful (Mandelbrot, 1982). Especially methods like map-counting (Kruhl et al., 2004), based on the classical box-counting method, or the modified Cantor-dust method (Volland & Kruhl, 2004) may be used for analyzing meter sized magmatic mineral distribution patterns in granitic rocks and the anisotropic behavior of micro- to macro scale fracture patterns in breccias. Nevertheless, these methods are performed manually and, therefore, not applicable to larger datasets. This study shows the next step towards automated recognition and subsequent quantification of magmatic patterns from micro- to macro-scale. Microstructure shape- and crystallographic preferred orientation measurements on K-feldspar crystals from the Piquiri Syenite Body, Southern Brazil are done manually based on thin-section series parallel to the syenite magmatic foliation. In addition U-stage measurements of K-feldspar indicatrix axis and (010) have been done. Additionally, a slightly changed modified Cantor-dust method was applied on centimeter- to several meter-sized K-feldspar phase distribution patterns, gained by automated image processing

  19. 49 CFR 195.122 - Fabricated branch connections.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF... system must be designed so that the addition of any fabricated branch connections will not reduce the strength of the pipeline system....

  20. 49 CFR 195.122 - Fabricated branch connections.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF... system must be designed so that the addition of any fabricated branch connections will not reduce the strength of the pipeline system....

  1. PAINT SHOP, DETAIL OF FABRICATED COLUMN AT JUNCTION OF WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PAINT SHOP, DETAIL OF FABRICATED COLUMN AT JUNCTION OF WEST BAY (ORIGINAL) AND CENTER BAYS (SECOND ADDITION), LOOKING NORTHEAST. - Southern Pacific, Sacramento Shops, Paint Shop, 111 I Street, Sacramento, Sacramento County, CA

  2. Fabrication of Metallic Hollow Nanoparticles

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  3. CONTAINER MATERIALS, FABRICATION AND ROBUSTNESS

    SciTech Connect

    Dunn, K.; Louthan, M.; Rawls, G.; Sindelar, R.; Zapp, P.; Mcclard, J.

    2009-11-10

    The multi-barrier 3013 container used to package plutonium-bearing materials is robust and thereby highly resistant to identified degradation modes that might cause failure. The only viable degradation mechanisms identified by a panel of technical experts were pressurization within and corrosion of the containers. Evaluations of the container materials and the fabrication processes and resulting residual stresses suggest that the multi-layered containers will mitigate the potential for degradation of the outer container and prevent the release of the container contents to the environment. Additionally, the ongoing surveillance programs and laboratory studies should detect any incipient degradation of containers in the 3013 storage inventory before an outer container is compromised.

  4. Directed light fabrication

    NASA Astrophysics Data System (ADS)

    Lewis, G. K.; Nemec, R.; Milewski, J.; Thoma, D. J.; Cremers, D.; Barbe, M.

    1994-09-01

    Directed Light Fabrication (DLF) is a rapid prototyping process being developed at Los Alamos National Laboratory to fabricate metal components. This is done by fusing gas delivered metal powder particles in the focal zone of a laser beam that is programmed to move along or across the part cross section. Fully dense metal is built up a layer at a time to form the desired part represented by a 3 dimensional solid model from CAD software. Machine 'tool paths' are created from the solid model that command the movement and processing parameters specific to the DLF process so that the part can be built one layer at a time. The result is a fully dense, near net shape metal part that solidifies under rapid solidification conditions.

  5. The Fabric of Reality

    NASA Astrophysics Data System (ADS)

    Whitaker, Andrew

    David Deutsch, The Fabric of Reality (London: Allen Lane, 1997), x+390 pp., ISBN 0-713-990619, hardback. David Deutsch's popular book, The Fabric of Reality, has already won acclaim as a sustained and comprehensible explanation of his own worldview, which encompasses his four main strands of quantum physics, epistemology, computation and evolution, as well as the many connections between them. Deutsch is a strong opponent of reductionism, and the latter three strands are 'high level' theories compared to quantum physics; but all four are to be regarded as fundamental because they are the theories that provide the deepest explanations. Deutsch considers that his worldview may be called the first genuine Theory of Everything; it would stand in strong contrast to the reductionist theories given that title at present. In fact he believes his approach may enable us to unify and explain not just science, but philosophy, logic, mathematics, ethics, politics and aesthetics.

  6. Automated breeder fuel fabrication

    SciTech Connect

    Goldmann, L.H.; Frederickson, J.R.

    1983-09-01

    The objective of the Secure Automated Fabrication (SAF) Project is to develop remotely operated equipment for the processing and manufacturing of breeder reactor fuel pins. The SAF line will be installed in the Fuels and Materials Examination Facility (FMEF). The FMEF is presently under construction at the Department of Energy's (DOE) Hanford site near Richland, Washington, and is operated by the Westinghouse Hanford Company (WHC). The fabrication and support systems of the SAF line are designed for computer-controlled operation from a centralized control room. Remote and automated fuel fabriction operations will result in: reduced radiation exposure to workers; enhanced safeguards; improved product quality; near real-time accountability, and increased productivity. The present schedule calls for installation of SAF line equipment in the FMEF beginning in 1984, with qualifying runs starting in 1986 and production commencing in 1987. 5 figures.

  7. Fabrication of freeform optics

    NASA Astrophysics Data System (ADS)

    Blalock, Todd; Medicus, Kate; DeGroote Nelson, Jessica

    2015-08-01

    Freeform surfaces on optical components have become an important design tool for optical designers. Non-rotationally symmetric optical surfaces have made solving complex optical problems easier. The manufacturing and testing of these surfaces has been the technical hurdle in freeform optic's wide-spread use. Computer Numerically Controlled (CNC) optics manufacturing technology has made the fabrication of optical components more deterministic and streamlined for traditional optics and aspheres. Optimax has developed a robust freeform optical fabrication CNC process that includes generation, high speed VIBE polishing, sub-aperture figure correction, surface smoothing and testing of freeform surfaces. Metrology of freeform surface is currently achieved with coordinate measurement machines (CMM) for lower resolution and interferometry with computer generated holograms (CGH) for high resolution irregularity measurements.

  8. Ceramic fabrication R D

    SciTech Connect

    Not Available

    1990-01-01

    This project is separated into three tasks. The first task is a design and modeling effort to be carried out by MSE, Inc. The purpose of this task is to develop and analyze designs for various cohesive ceramic fabrication (CCF) components, including an MHD electrode for strategic defense initiative (SDI) applications and a high stress, low cost, reinforced ceramic component for armor applications. The MHD electrode design is substantially completed. A layered structure composed of molybdenum disilicide graded with quartz glass has been designed and analyzed using finite element methods. The design demonstrates the fabrication capabilities of the CCF process. The high stress, armor application component will be silicon carbide reinforced alumina in thick plates. 2 refs., 4 figs., 1 tab.

  9. Physical modeling of stepped spillways

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stepped spillways applied to embankment dams are becoming popular for addressing the rehabilitation of aging watershed dams, especially those situated in the urban landscape. Stepped spillways are typically placed over the existing embankment, which provides for minimal disturbance to the original ...

  10. Development of a "Steps Questionnaire".

    PubMed

    Gilbert, F S

    1991-07-01

    Thousands of men and women have begun their recovery from alcoholism through the support of Alcoholics Anonymous (AA) and its well-known "12-Step" program. The purpose of the present study was to develop a scale to measure alcoholics' levels of agreement with the first three of AA's 12 Steps and to test the relationship between sobriety and belief in these three steps. Using both factor analysis and Rasch analysis, two versions of a "Steps Questionnaire" were developed. A 96-member subset of the original subject pool was assessed quarterly for 1 year following inpatient treatment to determine the predictive validity of the questionnaire. The results of this study suggested that agreement with AA's first three steps can be measured and that agreement with AA's first step correlates with number of sober days posttreatment. The dichotomization of Steps Questionnaire scores into total agreement versus partial agreement with Step 1, and from this the reduction of uncertainty in the prediction of abstention over a lengthy follow-up period, provides support for AA's contention that total surrender to one's powerlessness over alcohol is part of the process of achieving abstention.

  11. Space Fabrication Demonstration System

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The completion of assembly of the beam builder and its first automatic production of truss is discussed. A four bay, hand assembled, roll formed members truss was built and tested to ultimate load. Detail design of the fabrication facility (beam builder) was completed and designs for subsystem debugging are discussed. Many one bay truss specimens were produced to demonstrate subsystem operation and to detect problem areas.

  12. Space Fabrication Demonstration System

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Progress on fabrication facility (beam builder) support structure control, clamp/weld block, and welding and truss cut off is discussed. The brace attachment design was changed and the design of the weld mechanism was modified which achieved the following system benefits: (1) simplified weld electrode life; (2) reduced weld power requirements; and (3) simplified brace attachment mechanisms. Static and fatigue characteristics of spot welded 2024T3 aluminum joints are evaluated.

  13. Space Fabrication Demonstration System

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Progress in the development of a beam builder to be deployed by space shuttle for assembly of large structures in space is reported. The thermal coating for the structural truss was selected and the detail truss design and analysis completed. Data acquired during verification of the design of the basic 'building block' truss are included as well as design layouts for various fabrication facility subsystems.

  14. Additive Construction using Basalt Regolith Fines

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Lippitt, Thomas C.; Mantovani, James G.; Nugent, Matthew W.; Townsend, Ivan I.

    2014-01-01

    Planetary surfaces are often covered in regolith (crushed rock), whose geologic origin is largely basalt. The lunar surface is made of small-particulate regolith and areas of boulders located in the vicinity of craters. Regolith composition also varies with location, reflecting the local bedrock geology and the nature and efficiency of the micrometeorite-impact processes. In the lowland mare areas (suitable for habitation), the regolith is composed of small granules (20 - 100 microns average size) of mare basalt and volcanic glass. Impacting micrometeorites may cause local melting, and the formation of larger glassy particles, and this regolith may contain 10-80% glass. Studies of lunar regolith are traditionally conducted with lunar regolith simulant (reconstructed soil with compositions patterned after the lunar samples returned by Apollo). The NASA Kennedy Space Center (KSC) Granular Mechanics & Regolith Operations (GMRO) lab has identified a low fidelity but economical geo-technical simulant designated as Black Point-1 (BP-1). It was found at the site of the Arizona Desert Research and Technology Studies (RATS) analog field test site at the Black Point lava flow in adjacent basalt quarry spoil mounds. This paper summarizes activities at KSC regarding the utilization of BP-1 basalt regolith and comparative work with lunar basalt simulant JSC-1A as a building material for robotic additive construction of large structures. In an effort to reduce the import or in-situ fabrication of binder additives, we focused this work on in-situ processing of regolith for construction in a single-step process after its excavation. High-temperature melting of regolith involves techniques used in glassmaking and casting (with melts of lower density and higher viscosity than those of metals), producing basaltic glass with high durability and low abrasive wear. Most Lunar simulants melt at temperatures above 1100 C, although melt processing of terrestrial regolith at 1500 C is not

  15. Fabrication of lightweight ceramic mirrors by means of a chemical vapor deposition process

    NASA Technical Reports Server (NTRS)

    Goela, Jitendra S. (Inventor); Taylor, Raymond L. (Inventor)

    1991-01-01

    A process to fabricate lightweigth ceramic mirrors, and in particular, silicon/silicon carbide mirrors, involves three chemical vapor deposition steps: one to produce the mirror faceplate, the second to form the lightweight backstructure which is deposited integral to the faceplate, and the third and final step which results in the deposition of a layer of optical grade material, for example, silicon, onto the front surface of the faceplate. The mirror figure and finish are fabricated into this latter material.

  16. Fabrication and Characterization of CNT-Based Smart Tips for Synchrotron Assisted STM

    DOE PAGES

    Yan, Hui; Cummings, Marvin; Camino, Fernando; Xu, Weihe; Lu, Ming; Tong, Xiao; Shirato, Nozomi; Rosenmann, Daniel; Rose, Volker; Nazaretski, Evgeny

    2015-01-01

    Determination of chemical composition along with imaging at the atomic level provides critical information towards fundamental understanding of the surface of materials and, hence, yields the capability to design new materials by tailoring their ultimate functionalities. Synchrotron X-ray assisted scanning tunneling microscopy (SX-STM) is a promising new technique to achieve real space chemically specific atomic mapping. Chemical sensitivity of SX-STM relies on excitation of core electrons by incident X-rays when their energy is tuned to an absorption edge of a particular element. However, along with core-level electrons, photoelectrons are also excited, which yield additional current and interfere with the tunnelingmore » current. To reduce the background photoelectron current and to improve ultimate resolution of SX-STM, we have developed and fabricated multiwalled carbon nanotubes (MWCNT) based “smart tips” using plasma enhanced chemical vapor deposition and focused ion beam milling. The newly developed CNT-based smart tips, characterized step by step by scanning electron microscopy (SEM) during the fabrication process, demonstrate good performance and provide opportunity for realizing atomic chemical mapping.« less

  17. High-temperature fabricable nickel-iron aluminides

    DOEpatents

    Liu, Chain T.

    1988-02-02

    Nickel-iron aluminides are described that are based on Ni.sub.3 Al, and have significant iron content, to which additions of hafnium, boron, carbon and cerium are made resulting in Ni.sub.3 Al base alloys that can be fabricated at higher temperatures than similar alloys previously developed. Further addition of molybdenum improves oxidation and cracking resistance. These alloys possess the advantages of ductility, hot fabricability, strength, and oxidation resistance.

  18. The Testing of Airplane Fabrics

    NASA Technical Reports Server (NTRS)

    Schraivogel, Karl

    1932-01-01

    This report considers the determining factors in the choice of airplane fabrics, describes the customary methods of testing and reports some of the experimental results. To sum up briefly the results obtained with the different fabrics, it may be said that increasing the strength of covering fabrics by using coarser yarns ordinarily offers no difficulty, because the weight increment from doping is relatively smaller.

  19. A 140-element Ge detector fabricated using amorphous Ge blocking contacts

    SciTech Connect

    Luke, P.N.; Pehl, R.H.; Dilmanian, F.A.

    1993-10-01

    A 140-element position-sensitive Ge detector has been fabricated as the prototype detector for the development of a monochromatic computed tomography system using synchrotron radiation. The detector was made in very few processing steps that included the use of amorphous Ge blocking contacts. The fabrication process and the results of testing the detector are described.

  20. Scaling the Ivy Wall: 12 Winning Steps to College Admission.

    ERIC Educational Resources Information Center

    Greene, Howard; Minton, Robert

    A 12-step plan for investigating colleges and making college choices is presented for college applicants. In addition to information on selective college admissions, the 12 chapters cover the following steps: knowing admission requirements and procedures, determining the student's strengths, following a demanding curriculum, taking advantage of…

  1. Improvements to constitutive material model for fabrics

    NASA Astrophysics Data System (ADS)

    Morea, Mihai I.

    2011-12-01

    The high strength to weight ratio of woven fabric offers a cost effective solution to be used in a containment system for aircraft propulsion engines. Currently, Kevlar is the only Federal Aviation Administration (FAA) approved fabric for usage in systems intended to mitigate fan blade-out events. This research builds on an earlier constitutive model of Kevlar 49 fabric developed at Arizona State University (ASU) with the addition of new and improved modeling details. Latest stress strain experiments provided new and valuable data used to modify the material model post peak behavior. These changes reveal an overall improvement of the Finite Element (FE) model's ability to predict experimental results. First, the steel projectile is modeled using Johnson-Cook material model and provides a more realistic behavior in the FE ballistic models. This is particularly noticeable when comparing FE models with laboratory tests where large deformations in projectiles are observed. Second, follow-up analysis of the results obtained through the new picture frame tests conducted at ASU provides new values for the shear moduli and corresponding strains. The new approach for analysis of data from picture frame tests combines digital image analysis and a two-level factorial optimization formulation. Finally, an additional improvement in the material model for Kevlar involves checking the convergence at variation of mesh density of fabrics. The study performed and described herein shows the converging trend, therefore validating the FE model.

  2. Additive manufacturing of hybrid circuits

    DOE PAGES

    Bell, Nelson S.; Sarobol, Pylin; Cook, Adam; Clem, Paul G.; Keicher, David M.; Hirschfeld, Deidre; Hall, Aaron Christopher

    2016-03-26

    There is a rising interest in developing functional electronics using additively manufactured components. Considerations in materials selection and pathways to forming hybrid circuits and devices must demonstrate useful electronic function; must enable integration; and must complement the complex shape, low cost, high volume, and high functionality of structural but generally electronically passive additively manufactured components. This article reviews several emerging technologies being used in industry and research/development to provide integration advantages of fabricating multilayer hybrid circuits or devices. First, we review a maskless, noncontact, direct write (DW) technology that excels in the deposition of metallic colloid inks for electrical interconnects.more » Second, we review a complementary technology, aerosol deposition (AD), which excels in the deposition of metallic and ceramic powder as consolidated, thick conformal coatings and is additionally patternable through masking. As a result, we show examples of hybrid circuits/devices integrated beyond 2-D planes, using combinations of DW or AD processes and conventional, established processes.« less

  3. Step-by-step growth of complex oxide microstructures

    SciTech Connect

    Datskos, Panos G.; Cullen, David A.; Sharma, Jaswinder K.

    2015-06-10

    The synthesis of complex and hybrid oxide microstructures is of fundamental interest and practical applications. However, the design and synthesis of such structures is a challenging task. We developed a solution phase process to synthesize complex silica and silica titania hybrid microstructures by exploiting the emulsion droplet based shape control and step by step growth. The strategy is robust and can be extended to make complex hybrid structures made of two or more materials while each having its own shape.

  4. Tannic acid NPs - synthesis and immobilization onto a solid surface in a one-step process and their antibacterial and anti-inflammatory properties.

    PubMed

    Perelshtein, Ilana; Ruderman, Elena; Francesko, Antonio; Fernandes, Margarida M; Tzanov, Tzanko; Gedanken, Aharon

    2014-11-01

    Tannic acid nanoparticles were synthesized from an aqueous solution without the use of stabilizers via a sonochemical process. In order to avoid the dissolution of the formed nanoparticles, the sonochemical reaction was performed in the presence of a cotton fabric: following their formation, the tannic acid nanoparticles were embedded into the cotton substrate in a one-step process. The bioactive properties of the tannic acid coated surface were examined towards the inhibition of myeloperoxidase and collagenase, two major enzymes related with inflammatory processes. In addition, the antibacterial activity of the tannic acid nanoparticles coated textiles was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa.

  5. Two-step electroweak baryogenesis

    NASA Astrophysics Data System (ADS)

    Inoue, Satoru; Ovanesyan, Grigory; Ramsey-Musolf, Michael J.

    2016-01-01

    We analyze electroweak baryogenesis during a two-step electroweak symmetry-breaking transition, wherein the baryon asymmetry is generated during the first step and preserved during the second. Focusing on the dynamics of C P violation required for asymmetry generation, we discuss general considerations for successful two-step baryogenesis. Using a concrete model realization, we illustrate in detail the viability of this scenario and the implications for present and future electric dipole moment (EDM) searches. We find that C P violation associated with a partially excluded sector may yield the observed baryon asymmetry while evading present and future EDM constraints.

  6. Wavelet transform: a future of rock fabric analysis?

    NASA Astrophysics Data System (ADS)

    Gaillot, Philippe; Darrozes, José; Bouchez, Jean-Luc

    1999-11-01

    Although twenty years ago fabric was defined as "the complete spatial and geometrical configuration of all those components that make up a deformed rock", fabric was mainly synonymous with lattice preferred orientation. Very little attention has been paid to the multi-scale geometrical and spatial relationships of the rock components. Fabric quantification, in terms of size, shape, orientation and location, at all scales, is now performed in two dimensions using anisotropic wavelets. As a first example, the wavelets are applied to the famous colour plate of Sander, and the results compared to his Axial Distribution Analysis. Applied to the K-feldspars of a rock section from the Sidobre granite pluton (Montagne Noire, France), the wavelet analysis shows: (i) alignment of grains, resulting from mechanical interactions between grains, and shows that shearing occurred within the crystalline frame; (ii) preferred grain orientation, the classical grain-shape fabric, parallel to the overall mineral lineation; and (iii) small tensional domains, elongate perpendicular to the lineation, infilled by the residual melt just before total crystallisation, attesting to the stretching nature of the mineral lineation. The future of rock fabric analysis will come from new steps in understanding the processes acting during fabric development along with a further development of wavelet analysis using high resolution three-dimensional fabric data.

  7. Fabrication of a tantalum-clad tungsten target for LANSCE

    NASA Astrophysics Data System (ADS)

    Nelson, A. T.; O'Toole, J. A.; Valicenti, R. A.; Maloy, S. A.

    2012-12-01

    Development of a solid state bonding technique suitable to clad tungsten targets with tantalum was completed to improve operation of the Los Alamos Neutron Science Centers spallation target. Significant deterioration of conventional bare tungsten targets has historically resulted in transfer of tungsten into the cooling system through corrosion resulting in increased radioactivity outside the target and reduction of delivered neutron flux. The fabrication method chosen to join the tantalum cladding to the tungsten was hot isostatic pressing (HIP) given the geometry constraints of a cylindrical assembly and previous success demonstrated at KENS. Nominal HIP parameters of 1500 °C, 200 MPa, and 3 h were selected based upon previous work. Development of the process included significant surface engineering controls and characterization given tantalums propensity for oxide and carbide formation at high temperatures. In addition to rigorous acid cleaning implemented at each step of the fabrication process, a three layer tantalum foil gettering system was devised such that any free oxygen and carbon impurities contained in the argon gas within the HIP vessel was mitigated to the extent possible before coming into contact with the tantalum cladding. The result of the numerous controls and refined techniques was negligible coarsening of the native Ta2O5 surface oxide, no measureable oxygen diffusion into the tantalum bulk, and no detectable carburization despite use of argon containing up to 5 ppm oxygen and up to 40 ppm total CO, CO2, or organic contaminants. Post bond characterization of the interface revealed continuous bonding with a few microns of species interdiffusion.

  8. Tactile Fabric Panel in an Eight Zones Structure

    PubMed Central

    Alsina, Maria; Escudero, Francesc; Margalef, Jordi; Luengo, Sonia

    2007-01-01

    By introducing a percentage of conductive material during the manufacture of sewing thread, it is possible to obtain a fabric which is able to detect variations in pressure in certain areas. In previous experiments the existence of resistance variations has been demonstrated, although some constrains of cause and effect were found in the fabric. The research has been concentrated in obtaining a fabric that allows electronic detection of its shape changes. Additionally, and because a causal behavior is needed, it is necessary that the fabric recovers its original shape when the external forces cease. The structure of the fabric varies with the type of deformation applied. Two kinds of deformation are described: those caused by stretching and those caused by pressure. This last type of deformation gives different responses depending on the conductivity of the object used to cause the pressure. This effect is related to the type of thread used to manufacture the fabric. So, if the pressure is caused by a finger the response is different compared to the response caused by a conductive object. Another fact that has to be mentioned is that a pressure in a specific point of the fabric can affect other detection points depending on the force applied. This effect is related to the fabric structure. The goals of this article are validating the structure of the fabric used, as well as the study of the two types of deformation mentioned before.

  9. One-step large-scale deposition of salt-free DNA origami nanostructures

    PubMed Central

    Linko, Veikko; Shen, Boxuan; Tapio, Kosti; Toppari, J. Jussi; Kostiainen, Mauri A.; Tuukkanen, Sampo

    2015-01-01

    DNA origami nanostructures have tremendous potential to serve as versatile platforms in self-assembly -based nanofabrication and in highly parallel nanoscale patterning. However, uniform deposition and reliable anchoring of DNA nanostructures often requires specific conditions, such as pre-treatment of the chosen substrate or a fine-tuned salt concentration for the deposition buffer. In addition, currently available deposition techniques are suitable merely for small scales. In this article, we exploit a spray-coating technique in order to resolve the aforementioned issues in the deposition of different 2D and 3D DNA origami nanostructures. We show that purified DNA origamis can be controllably deposited on silicon and glass substrates by the proposed method. The results are verified using either atomic force microscopy or fluorescence microscopy depending on the shape of the DNA origami. DNA origamis are successfully deposited onto untreated substrates with surface coverage of about 4 objects/mm2. Further, the DNA nanostructures maintain their shape even if the salt residues are removed from the DNA origami fabrication buffer after the folding procedure. We believe that the presented one-step spray-coating method will find use in various fields of material sciences, especially in the development of DNA biochips and in the fabrication of metamaterials and plasmonic devices through DNA metallisation. PMID:26492833

  10. Intraocular lens fabrication

    DOEpatents

    Salazar, Mike A.; Foreman, Larry R.

    1997-01-01

    This invention describes a method for fabricating an intraocular lens made rom clear Teflon.TM., Mylar.TM., or other thermoplastic material having a thickness of about 0.025 millimeters. These plastic materials are thermoformable and biocompatable with the human eye. The two shaped lenses are bonded together with a variety of procedures which may include thermosetting and solvent based adhesives, laser and impulse welding, and ultrasonic bonding. The fill tube, which is used to inject a refractive filling material is formed with the lens so as not to damage the lens shape. A hypodermic tube may be included inside the fill tube.

  11. Intraocular lens fabrication

    DOEpatents

    Salazar, M.A.; Foreman, L.R.

    1997-07-08

    This invention describes a method for fabricating an intraocular lens made from clear Teflon{trademark}, Mylar{trademark}, or other thermoplastic material having a thickness of about 0.025 millimeters. These plastic materials are thermoformable and biocompatable with the human eye. The two shaped lenses are bonded together with a variety of procedures which may include thermosetting and solvent based adhesives, laser and impulse welding, and ultrasonic bonding. The fill tube, which is used to inject a refractive filling material is formed with the lens so as not to damage the lens shape. A hypodermic tube may be included inside the fill tube. 13 figs.

  12. Electrochemical fabrication of capacitors

    DOEpatents

    Mansour, Azzam N.; Melendres, Carlos A.

    1999-01-01

    A film of nickel oxide is anodically deposited on a graphite sheet held in osition on an electrochemical cell during application of a positive electrode voltage to the graphite sheet while exposed to an electrolytic nickel oxide solution within a volumetrically variable chamber of the cell. An angularly orientated x-ray beam is admitted into the cell for transmission through the deposited nickel oxide film in order to obtain structural information while the film is subject to electrochemical and in-situ x-ray spectroscopy from which optimum film thickness, may be determined by comparative analysis for capacitor fabrication purposes.

  13. PRSEUS Acoustic Panel Fabrication

    NASA Technical Reports Server (NTRS)

    Nicolette, Velicki; Yovanof, Nicolette P.; Baraja, Jaime; Mathur, Gopal; Thrash, Patrick; Pickell, Robert

    2011-01-01

    This report describes the development of a novel structural concept, Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), that addresses the demanding fuselage loading requirements for the Hybrid Wing or Blended Wing Body (BWB) airplane configuration with regards to acoustic response. A PRSEUS panel was designed and fabricated and provided to NASA-LaRC for acoustic response testing in the Structural Acoustics Loads and Transmission (SALT) facility). Preliminary assessments of the sound transmission characteristics of a PRSEUS panel subjected to a representative Hybrid Wing Body (HWB) operating environment were completed for the NASA Environmentally Responsible Aviation (ERA) Program.

  14. Fabrication of metal nanoshells

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, Jr., James R. (Inventor)

    2012-01-01

    Metal nanoshells are fabricated by admixing an aqueous solution of metal ions with an aqueous solution of apoferritin protein molecules, followed by admixing an aqueous solution containing an excess of an oxidizing agent for the metal ions. The apoferritin molecules serve as bio-templates for the formation of metal nanoshells, which form on and are bonded to the inside walls of the hollow cores of the individual apoferritin molecules. Control of the number of metal atoms which enter the hollow core of each individual apoferritin molecule provides a hollow metal nonparticle, or nanoshell, instead of a solid spherical metal nanoparticle.

  15. The utilization of microwave heating for the fabrication of sintered reaction-bonded silicon nitride

    SciTech Connect

    Kiggans, J.O.; Tiegs, T.N.; Lin, H.T.; Holcombe, C.E.

    1995-12-31

    The results of studies in which microwave heating was used to fabricate sintered reaction-bonded silicon nitride (SRBSN) are reviewed. These results are compared to parallel studies where conventional heating was used for the fabrication of these materials. Microwave fabrication of SRBSN involves a single heating cycle, whereas conventional processing requires two separate furnace runs and sample packaging steps. SRBSN containing high levels of sintering aids which were fabricated by microwave heating showed improved strength and toughness, as compared to those materials fabricated using a conventional resistance-heated furnace. An analysis of the microstructures of the microwave fabricated materials showed enhanced acicular grain growth as compared to conventionally heated material. Results are presented on studies involving the scale-up of the microwave fabrication process.

  16. Wafer-scale micro-optics fabrication

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard

    2012-07-01

    Micro-optics is an indispensable key enabling technology for many products and applications today. Probably the most prestigious examples are the diffractive light shaping elements used in high-end DUV lithography steppers. Highly-efficient refractive and diffractive micro-optical elements are used for precise beam and pupil shaping. Micro-optics had a major impact on the reduction of aberrations and diffraction effects in projection lithography, allowing a resolution enhancement from 250 nm to 45 nm within the past decade. Micro-optics also plays a decisive role in medical devices (endoscopes, ophthalmology), in all laser-based devices and fiber communication networks, bringing high-speed internet to our homes. Even our modern smart phones contain a variety of micro-optical elements. For example, LED flash light shaping elements, the secondary camera, ambient light and proximity sensors. Wherever light is involved, micro-optics offers the chance to further miniaturize a device, to improve its performance, or to reduce manufacturing and packaging costs. Wafer-scale micro-optics fabrication is based on technology established by the semiconductor industry. Thousands of components are fabricated in parallel on a wafer. This review paper recapitulates major steps and inventions in wafer-scale micro-optics technology. The state-of-the-art of fabrication, testing and packaging technology is summarized.

  17. Fabrication of the CALDER light detectors

    NASA Astrophysics Data System (ADS)

    Colantoni, I.; Bellini, F.; Cardani, L.; Casali, N.; Castellano, M. G.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D`Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2016-07-01

    CALDER (Cryogenic wide-Area Light Detectors with Excellent Resolution) is a project for the development of large area phonon mediated KIDs (Kinetic Inductance Detectors), for the detection of Cherenkov radiation emitted in TeO2 bolometers to search for neutrinoless double beta decay (0 νββ). The KIDs are superconducting detectors made of high quality factor superconducting resonators, which are coupled to a transmission line for signal readout. We designed and fabricated KIDs using aluminum. The Al thin films (40 nm) were evaporated on Si(100) high resistivity silicon wafers using an electron beam evaporator in a HV chamber. In this work we report the steps of the fabrication process. All devices are made in direct-write using Electron Beam Lithography (EBL), positive tone resist poly-methyl methacrylate (PMMA) and lift off process. In order to improve the sensitivity of the detectors we have started recently to use sub-stoichiometric TiN deposited by means of DC magnetron sputtering and we will optimize a different fabrication process.

  18. Recent developments in wafer-level fabrication of micro-optical multi-aperture imaging systems

    NASA Astrophysics Data System (ADS)

    Leitel, R.; Dannberg, P.; Brückner, A.; Bräuer, A.

    2011-10-01

    Micro-optical systems, that utilize multiple channels for imaging instead of a single one, are frequently discussed for ultra-compact applications such as digital cameras. The strategy of their fabrication differs due to different concepts of image formation. Illustrated by recently implemented systems for multi-aperture imaging, typical steps of wafer-level fabrication are discussed in detail. In turn, the made progress may allow for additional degrees of freedom in optical design. Pressing ahead with very short overall lengths and multiple diaphragm array layers, results in the use of extremely thin glass substrates down to 100 microns in thickness. The desire for a wide field of view for imaging has led to chirped arrays of microlenses and diaphragms. Focusing on imaging quality, aberrations were corrected by introducing toroidal lenslets and elliptical apertures. Such lenslets had been generated by thermal reflow of lithographic patterned photoresist and subsequent molding. Where useful, the system's performance can be further increased by applying aspheric microlenses from reactive ion etching (RIE) transfer or by achromatic doublets from superimposing two moldings with different polymers. Multiple diaphragm arrays prevent channel crosstalk. But using simple metal layers may lead to multiple reflections and an increased appearance of ghost images. A way out are low reflecting black matrix polymers that can be directly patterned by lithography. But in case of environmental stability and high resolution, organic coatings should be replaced by patterned metal coatings that exhibit matched antireflective layers like the prominent black chromium. The mentioned components give an insight into the fabrication process of multi-aperture imaging systems. Finally, the competence in each step decides on the overall image quality.

  19. Fabrication and electrochemical performance of 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 microspheres by two-step spray-drying process

    NASA Astrophysics Data System (ADS)

    Son, Mun Yeong; Lee, Jung-Kul; Kang, Yun Chan

    2014-08-01

    0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures are prepared by a two-step spray-drying process. Precursor powders with hollow and porous structures prepared by the spray-drying process are post-treated at a low temperature of 400°C and then wet-milled to obtain a slurry with high stability. The slurry of the mixture of metal oxides is spray-dried to prepare precursor aggregate powders several microns in size. Post-treatment of these powders at high temperatures (>700°C) produces 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures and high crystallinity. The mean size and geometric standard deviation of the composite microspheres post-treated at 900°C are 4 μm and 1.38, respectively. Further, the initial charge capacities of the aggregated microspheres post-treated at 700, 800, 900, and 1000°C are 336, 349, 383, and 128 mA h g-1, respectively, and the corresponding discharge capacities are 286, 280, 302, and 77 mA h g-1, respectively. The discharge capacity of the composite microspheres post-treated at an optimum temperature of 900°C after 100 cycles is 242 mA h g-1, and the corresponding capacity retention is 80%.

  20. Fabrication and electrochemical performance of 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 microspheres by two-step spray-drying process

    PubMed Central

    Son, Mun Yeong; Lee, Jung-Kul; Kang, Yun Chan

    2014-01-01

    0.6Li2MnO3–0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures are prepared by a two-step spray-drying process. Precursor powders with hollow and porous structures prepared by the spray-drying process are post-treated at a low temperature of 400°C and then wet-milled to obtain a slurry with high stability. The slurry of the mixture of metal oxides is spray-dried to prepare precursor aggregate powders several microns in size. Post-treatment of these powders at high temperatures (>700°C) produces 0.6Li2MnO3–0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures and high crystallinity. The mean size and geometric standard deviation of the composite microspheres post-treated at 900°C are 4 μm and 1.38, respectively. Further, the initial charge capacities of the aggregated microspheres post-treated at 700, 800, 900, and 1000°C are 336, 349, 383, and 128 mA h g−1, respectively, and the corresponding discharge capacities are 286, 280, 302, and 77 mA h g−1, respectively. The discharge capacity of the composite microspheres post-treated at an optimum temperature of 900°C after 100 cycles is 242 mA h g−1, and the corresponding capacity retention is 80%. PMID:25168912