A Strategy for DoD Manufacturing Science and Technology R and D in Precision Fabrication

DTIC Science & Technology

1994-01-01

3-11 vii Contents (Continued) Bibliography Appendix A. Progress Since the 1991 Plan Appendix B. Why "Precision" Appendix C...preci- sion fabrication R&D. Appendix A summarizes progress in precision fabrication R&D since the previous plan was prepared in 1991. Appendix B...lathe’s power consumption may indicate worn bearings. Detecting and acting on this condition can prevent costly spindle damage and associated machine down

Codoping method for the fabrication of low-resistivity wide band-gap semiconductors in p-type GaN, p-type AlN and n-type diamond: prediction versus experiment

NASA Astrophysics Data System (ADS)

Katayama-Yoshida, H.; Nishimatsu, T.; Yamamoto, T.; Orita, N.

2001-10-01

We review our new valence control method of a co-doping for the fabrication of low-resistivity p-type GaN, p-type AlN and n-type diamond. The co-doping method is proposed based upon ab initio electronic structure calculation in order to solve the uni-polarity and the compensation problems in the wide band-gap semiconductors. In the co-doping method, we dope both the acceptors and donors at the same time by forming the meta-stable acceptor-donor-acceptor complexes for the p-type or donor-acceptor-donor complexes for the n-type under thermal non-equilibrium crystal growth conditions. We propose the following co-doping method to fabricate the low-resistivity wide band-gap semiconductors; p-type GaN: [Si + 2 Mg (or Be)], [H + 2 Mg (or Be)], [O + 2 Mg (or Be)], p-type AlN: [O + 2 C] and n-type diamond: [B + 2 N], [H + S], [H + 2 P]. We compare our prediction of the co-doping method with the recent successful experiments to fabricate the low-resistivity p-type GaN, p-type AlN and n-type diamond. We show that the co-doping method is the efficient and universal doping method by which to avoid carrier compensation with an increase of the solubility of the dopant, to increase the activation rate by decreasing the ionization energy of acceptors and donors, and to increase the mobility of the carrier.

Low-resistance strip sensors for beam-loss event protection

NASA Astrophysics Data System (ADS)

Ullán, M.; Benítez, V.; Quirion, D.; Zabala, M.; Pellegrini, G.; Lozano, M.; Lacasta, C.; Soldevila, U.; García, C.; Fadeyev, V.; Wortman, J.; DeFilippis, J.; Shumko, M.; Grillo, A. A.; Sadrozinski, H. F.-W.

2014-11-01

AC-coupled silicon strip sensors can be damaged in case of a beam loss due to the possibility of a large charge accumulation in the bulk, developing very high voltages across the coupling capacitors which can destroy them. Punch-through structures are currently used to avoid this problem helping to evacuate the accumulated charge as large voltages are developing. Nevertheless, previous experiments, performed with laser pulses, have shown that these structures can become ineffective in relatively long strips. The large value of the implant resistance can effectively isolate the "far" end of the strip from the punch-through structure leading to large voltages. We present here our developments to fabricate low-resistance strip sensors to avoid this problem. The deposition of a conducting material in contact with the implants drastically reduces the strip resistance, assuring the effectiveness of the punch-through structures. First devices have been fabricated with this new technology. Initial results with laser tests show the expected reduction in peak voltages on the low resistivity implants. Other aspects of the sensor performance, including the signal formation, are not affected by the new technology.

Caracterisation electrique et vieillissement de resistances de silicium polycristallin modifiees par laser

NASA Astrophysics Data System (ADS)

Fantoni, Julie

2011-12-01

Several classes of integrated microelectronic circuits require highly precise and stable analog components that cannot be obtained directly through standard CMOS fabrication processes. Those components must thus be calibrated either by a modification of the fabrication process or by the application of a post-fabrication tuning procedure. Many successful post-fabrication tuning processes have been introduced in the field of resistor calibration, including resistor laser trimming which is the core subject of this thesis. In this thesis, trimmed components are standard CMOS 180nm technology polysilicon resistors, integrated in circuits specially designed to allow laser intervention on their surface. The laser used is a nanosecond pulsed laser for which the fluence is set below the melting threshold of polysilicon in order to prevent damage to the material structure. This novel low-power highly localized procedure reduces the risk of damaging sensitive surrounding circuits and requires no additional fabrication step, allowing smaller dies areas and reduced costs. Precise, reliable and reproducible devices have been tuned using this technique with a precision below 500 ppm. The main objective of this research is to study and analyze the effect of the laser parameters variation on the trimmed component properties and to optimize those parameters in regard of the desired precision and stability of the final product. Raman spectroscopic measurements are performed to observe and characterize structural modifications of the polysilicon material following laser irradiation as precise resistance measurements and standardized in-oven aging tests allow the complete characterization of the device in regard of precision and stability. It is shown that for a given precision, this novel low-power trimming technique produces devices with a stability comparable to those obtained with another trimming technology such as the pulsed current method. An electrical model is also developed

Resistive Switching in All-Printed, Flexible and Hybrid MoS2-PVA Nanocomposite based Memristive Device Fabricated by Reverse Offset

PubMed Central

Rehman, Muhammad Muqeet; Siddiqui, Ghayas Uddin; Gul, Jahan Zeb; Kim, Soo-Wan; Lim, Jong Hwan; Choi, Kyung Hyun

2016-01-01

Owing to the increasing interest in the nonvolatile memory devices, resistive switching based on hybrid nanocomposite of a 2D material, molybdenum disulphide (MoS2) and polyvinyl alcohol (PVA) is explored in this work. As a proof of concept, we have demonstrated the fabrication of a memory device with the configuration of PET/Ag/MoS2-PVA/Ag via an all printed, hybrid, and state of the art fabrication approach. Bottom Ag electrodes, active layer of hybrid MoS2-PVA nanocomposite and top Ag electrode are deposited by reverse offset, electrohydrodynamic (EHD) atomization and electrohydrodynamic (EHD) patterning respectively. The fabricated device displayed characteristic bistable, nonvolatile and rewritable resistive switching behavior at a low operating voltage. A decent off/on ratio, high retention time, and large endurance of 1.28 × 102, 105 sec and 1000 voltage sweeps were recorded respectively. Double logarithmic curve satisfy the trap controlled space charge limited current (TCSCLC) model in high resistance state (HRS) and ohmic model in low resistance state (LRS). Bendability test at various bending diameters (50-2 mm) for 1500 cycles was carried out to show the mechanical robustness of fabricated device. PMID:27811977

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

NASA Astrophysics Data System (ADS)

Ievlev, Anton V.; Chyasnavichyus, Marius; Leonard, Donovan N.; Agar, Joshua C.; Velarde, Gabriel A.; Martin, Lane W.; Kalinin, Sergei V.; Maksymovych, Petro; Ovchinnikova, Olga S.

2018-04-01

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ievlev, Anton; Chyasnavichyus, Marius; Leonard, Donovan N.

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy tomore » a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Lastly, our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.« less

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

DOE PAGES

Ievlev, Anton; Chyasnavichyus, Marius; Leonard, Donovan N.; ...

2018-02-22

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy tomore » a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Lastly, our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.« less

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness.

PubMed

Ievlev, Anton V; Chyasnavichyus, Marius; Leonard, Donovan N; Agar, Joshua C; Velarde, Gabriel A; Martin, Lane W; Kalinin, Sergei V; Maksymovych, Petro; Ovchinnikova, Olga S

2018-04-02

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

Fabrication of the Advanced X-ray Astrophysics Facility (AXAF) Optics: A Deterministic, Precision Engineering Approach to Optical Fabrication

NASA Technical Reports Server (NTRS)

Gordon, T. E.

1995-01-01

The mirror assembly of the AXAF observatory consists of four concentric, confocal, Wolter type 1 telescopes. Each telescope includes two conical grazing incidence mirrors, a paraboloid followed by a hyperboloid. Fabrication of these state-or-the-art optics is now complete, with predicted performance that surpasses the goals of the program. The fabrication of these optics, whose size and requirements exceed those of any previous x-ray mirrors, presented a challenging task requiring the use of precision engineering in many different forms. Virtually all of the equipment used for this effort required precision engineering. Accurate metrology required deterministic support of the mirrors in order to model the gravity distortions which will not be present on orbit. The primary axial instrument, known as the Precision Metrology Station (PMS), was a unique scanning Fizeau interferometer. After metrology was complete, the optics were placed in specially designed Glass Support Fixtures (GSF's) for installation on the Automated Cylindrical Grinder/Polishers (ACG/P's). The GSF's were custom molded for each mirror element to match the shape of the outer surface to minimize distortions of the inner surface. The final performance of the telescope is expected to far exceed the original goals and expectations of the program.

Effect of Spacecraft Environmental Variables on the Flammability of Fire Resistant Fabrics

NASA Astrophysics Data System (ADS)

Osorio, A. F.; Fernandez-Pello, C.; Takahashi, S.; Rodriguez, J.; Urban, D. L.; Ruff, G.

2012-01-01

Fire resistant fabrics are used for firefighter, racecar drivers as well as astronaut suits. However, their fire resistant characteristics depend on the environment conditions and require study. Particularly important is the response of these fabrics to elevated oxygen concentration environments and radiant heat from a source such as an adjacent fire. In this work, experiments using two fire resistant fabrics were conducted to study the effect of oxygen concentration, external radiant flux and oxidizer flow velocity in concurrent flame spread. Results show that for a given fabric the minimum oxygen concentration for flame spread depends strongly on the magnitude of the external radiant flux. At increased oxygen concentrations the external radiant flux required for flame spread decreases. Oxidizer flow velocity influences the external radiant flux only when the convective heat flux from the flame has similar values to the external radiant flux. The results of this work provide further understanding of the flammability characteristics of fire resistant fabrics in environments similar to those of future spacecrafts.

Precise Protein Photolithography (P3): High Performance Biopatterning Using Silk Fibroin Light Chain as the Resist

PubMed Central

Liu, Wanpeng; Zhou, Zhitao; Zhang, Shaoqing; Shi, Zhifeng; Tabarini, Justin; Lee, Woonsoo; Zhang, Yeshun; Gilbert Corder, S. N.; Li, Xinxin; Dong, Fei; Cheng, Liang; Liu, Mengkun; Kaplan, David L.; Omenetto, Fiorenzo G.

2017-01-01

Precise patterning of biomaterials has widespread applications, including drug release, degradable implants, tissue engineering, and regenerative medicine. Patterning of protein‐based microstructures using UV‐photolithography has been demonstrated using protein as the resist material. The Achilles heel of existing protein‐based biophotoresists is the inevitable wide molecular weight distribution during the protein extraction/regeneration process, hindering their practical uses in the semiconductor industry where reliability and repeatability are paramount. A wafer‐scale high resolution patterning of bio‐microstructures using well‐defined silk fibroin light chain as the resist material is presented showing unprecedent performances. The lithographic and etching performance of silk fibroin light chain resists are evaluated systematically and the underlying mechanisms are thoroughly discussed. The micropatterned silk structures are tested as cellular substrates for the successful spatial guidance of fetal neural stems cells seeded on the patterned substrates. The enhanced patterning resolution, the improved etch resistance, and the inherent biocompatibility of such protein‐based photoresist provide new opportunities in fabricating large scale biocompatible functional microstructures. PMID:28932678

Fabrication of a wide-field NIR integral field unit for SWIMS using ultra-precision cutting

NASA Astrophysics Data System (ADS)

Kitagawa, Yutaro; Yamagata, Yutaka; Morita, Shin-ya; Motohara, Kentaro; Ozaki, Shinobu; Takahashi, Hidenori; Konishi, Masahiro; Kato, Natsuko M.; Kobayakawa, Yutaka; Terao, Yasunori; Ohashi, Hirofumi

2016-07-01

We describe overview of fabrication methods and measurement results of test fabrications of optical surfaces for an integral field unit (IFU) for Simultaneous color Wide-field Infrared Multi-object Spectrograph, SWIMS, which is a first-generation instrument for the University of Tokyo Atacama Observatory 6.5-m telescope. SWIMS-IFU provides entire near-infrared spectrum from 0.9 to 2.5 μm simultaneously covering wider field of view of 17" × 13" compared with current near-infrared IFUs. We investigate an ultra-precision cutting technique to monolithically fabricate optical surfaces of IFU optics such as an image slicer. Using 4- or 5-axis ultra precision machine we compare the milling process and shaper cutting process to find the best way of fabrication of image slicers. The measurement results show that the surface roughness almost satisfies our requirement in both of two methods. Moreover, we also obtain ideal surface form in the shaper cutting process. This method will be adopted to other mirror arrays (i.e. pupil mirror and slit mirror, and such monolithic fabrications will also help us to considerably reduce alignment procedure of each optical elements.

Using femtosecond laser to fabricate highly precise interior three-dimensional microstructures in polymeric flow chip.

PubMed

Lee, Chia-Yu; Chang, Ting-Chou; Wang, Shau-Chun; Chien, Chih-Wei; Cheng, Chung-Wei

2010-10-18

This paper reports using femtosecond laser marker to fabricate the three-dimensional interior microstructures in one closed flow channel of plastic substrate. Strip-like slots in the dimensions of 800 μm×400 μm×65 μm were ablated with pulse Ti:sapphire laser at 800 nm (pulse duration of ∼120 fs with 1 kHz repetition rate) on acrylic slide. After ablation, defocused beams were used to finish the surface of microstructures. Having finally polished with sonication, the laser fabricated structures are highly precise with the arithmetic roughness of 1.5 and 4.5 nm. Fabricating such highly precise microstructures cannot be accomplished with nanosecond laser marking or other mechanical drilling methods. In addition, since laser ablation can directly engrave interior microstructures in one closed chip, glue smearing problems to damage molded microstructures possibly to occur during the chip sealing procedures can be avoided too.

Rugged Low-Resistance Contacts To High-Tc Superconductors

NASA Technical Reports Server (NTRS)

Caton, Randall; Selim, Raouf; Byvik, Charles E.; Buoncristiani, A. Martin

1992-01-01

Newly developed technique involving use of gold makes possible to fabricate low-resistance contacts with rugged connections to high-Tc superconductors. Gold diffused into specimen of superconducting material by melting gold beads onto surface of specimen, making strong mechanical contacts. Shear strength of gold bead contacts greater than epoxy or silver paste. Practical use in high-current-carrying applications of new high-Tc materials, including superconducting magnets, long-wavelength sensors, electrical ground planes at low temperatures, and efficient transmission of power.

Using femtosecond laser to fabricate highly precise interior three-dimensional microstructures in polymeric flow chip

PubMed Central

Lee, Chia-Yu; Chang, Ting-Chou; Wang, Shau-Chun; Chien, Chih-Wei; Cheng, Chung-Wei

2010-01-01

This paper reports using femtosecond laser marker to fabricate the three-dimensional interior microstructures in one closed flow channel of plastic substrate. Strip-like slots in the dimensions of 800 μm×400 μm×65 μm were ablated with pulse Ti:sapphire laser at 800 nm (pulse duration of ∼120 fs with 1 kHz repetition rate) on acrylic slide. After ablation, defocused beams were used to finish the surface of microstructures. Having finally polished with sonication, the laser fabricated structures are highly precise with the arithmetic roughness of 1.5 and 4.5 nm. Fabricating such highly precise microstructures cannot be accomplished with nanosecond laser marking or other mechanical drilling methods. In addition, since laser ablation can directly engrave interior microstructures in one closed chip, glue smearing problems to damage molded microstructures possibly to occur during the chip sealing procedures can be avoided too. PMID:21079695

Fibers and fabrics with insulating, water-proofing, and flame-resistant properties

DOEpatents

Hrubesh, Lawrence W.; Poco, John F.; Coronado, Paul R.

2004-04-20

Fibers, and fabrics produced from the fibers, are made water repellent, fire-retardant and/or thermally insulating by filling void spaces in the fibers and/or fabrics with a powdered material. When the powder is sufficiently finely divided, it clings tenaciously to the fabric's fibers and to itself, resisting the tendency to be removed from the fabric.

Low cost damage tolerant composite fabrication

NASA Technical Reports Server (NTRS)

Palmer, R. J.; Freeman, W. T.

1988-01-01

The resin transfer molding (RTM) process applied to composite aircraft parts offers the potential for using low cost resin systems with dry graphite fabrics that can be significantly less expensive than prepreg tape fabricated components. Stitched graphite fabric composites have demonstrated compression after impact failure performance that equals or exceeds that of thermoplastic or tough thermoset matrix composites. This paper reviews methods developed to fabricate complex shape composite parts using stitched graphite fabrics to increase damage tolerance with RTM processes to reduce fabrication cost.

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

PubMed Central

Vollebregt, Sten; Ishihara, Ryoichi

2015-01-01

We demonstrate a method for the low temperature growth (350 °C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-κ dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used. PMID:26709530

Facile fabrication of a poly(ethylene terephthalate) membrane filter with precise arrangement of through-holes

NASA Astrophysics Data System (ADS)

Kihara, Naoto; Odaka, Hidefumi; Kuboyama, Daiki; Onoshima, Daisuke; Ishikawa, Kenji; Baba, Yoshinobu; Hori, Masaru

2018-03-01

Although membrane filters are indispensable in biochemical analysis fields, most methods for through-hole fabrication are complex and inefficient. We developed a simple method of fabricating poly(ethylene terephthalate) (PET) membrane filters with a precise arrangement of through-holes for the isolation of circulating tumor cells (CTCs) based on their size. By photolithography and dry etching, highly packed 380,000 through-holes with a diameter of 7 µm were able to cover a whole area with a diameter of 13 mm. Device fabrication for the size-based capture of rare cells in blood such as CTCs is realized in this study.

Reliable low precision simulations in land surface models

NASA Astrophysics Data System (ADS)

Dawson, Andrew; Düben, Peter D.; MacLeod, David A.; Palmer, Tim N.

2017-12-01

Weather and climate models must continue to increase in both resolution and complexity in order that forecasts become more accurate and reliable. Moving to lower numerical precision may be an essential tool for coping with the demand for ever increasing model complexity in addition to increasing computing resources. However, there have been some concerns in the weather and climate modelling community over the suitability of lower precision for climate models, particularly for representing processes that change very slowly over long time-scales. These processes are difficult to represent using low precision due to time increments being systematically rounded to zero. Idealised simulations are used to demonstrate that a model of deep soil heat diffusion that fails when run in single precision can be modified to work correctly using low precision, by splitting up the model into a small higher precision part and a low precision part. This strategy retains the computational benefits of reduced precision whilst preserving accuracy. This same technique is also applied to a full complexity land surface model, resulting in rounding errors that are significantly smaller than initial condition and parameter uncertainties. Although lower precision will present some problems for the weather and climate modelling community, many of the problems can likely be overcome using a straightforward and physically motivated application of reduced precision.

Effect of surface treatments on physicomechanical, stain-resist, and UV protection properties of wool fabrics

NASA Astrophysics Data System (ADS)

Hassan, Mohammad M.; Leighs, Samuel J.

2017-10-01

The surface of wool fabrics is frequently modified to make them shrink-resistant, water repellent and also to improve their handle properties. In this work, we investigated the effect of common surface modification treatments on fabric stain-resistance, hydrophilicity and UV absorption performance. The surface of wool fabrics was modified by chlorination and also by reacting the chlorinated wool fabrics with a polyamide, a fibre-reactive amino-functional siloxane and a fluorocarbon polymer. The surface of the various treated fabrics was characterised by ATR-FTIR, contact angle measurement and scanning electron microscopy. The effect of surface modification on the tensile strength, surface hydrophilicity, stain-resistance, and UV absorption capacity of the fabric was investigated. It was found that all the treatments except the treatment with the amino-functional siloxane polymer slightly improved the tensile strength of the fabric. The chlorination treatment and the treatment with the polyamide resin made the fabric hydrophilic, and fluorocarbon and silicone resin treatment made the fabric hydrophobic.

Fabrication and characterization of high impact hybrid matrix composites from thermoset resin and dyneema-glass fabric reinforcement

NASA Astrophysics Data System (ADS)

Patel, R. H.; Sharma, S.; Pansuriya, T.; Malgani, E. V.; Sevkani, V.

2018-05-01

Hybrid composites have been fabricated by hand lay-up technique with epoxy resin and diethylene tri amine as a hardener for high impact energy absorption with sandwich stacking of different reinforcements of dyneema and glass fabric. High impact grade composites are nowadays gaining a lot of importance in the field of high mechanical load bearing applications, ballistics and bulletproofing. The present work emphases on the fabrication and mechanical properties of the hybrid composites of cut resistant dyneema fabric along with glass fabric reinforced in the thermosetting resin. i.e. epoxy. The prime importance while fabricating such materials have been given to the processing along with selection of the raw materials. High impact resistive materials with low density and henceforth low weight have been manufactured and characterized by IZOD impact tester, UTM, Archimedes density meter and SEM. Throughout the work, satisfactory results have been obtained. Impact resistance was observed to be boosted three times as that of the reference sample of glass fabric and epoxy. The density of the hybrid composite is observed to be 25% as that of the reference sample.

Nanoscale fabrication using single-ion impacts

NASA Astrophysics Data System (ADS)

Millar, Victoria; Pakes, Chris I.; Cimmino, Alberto; Brett, David; Jamieson, David N.; Prawer, Steven D.; Yang, Changyi; Rout, Bidhudutta; McKinnon, Rita P.; Dzurak, Andrew S.; Clark, Robert G.

2001-11-01

We describe a novel technique for the fabrication of nanoscale structures, based on the development of localized chemical modification caused in a PMMA resist by the implantation of single ions. The implantation of 2 MeV He ions through a thin layer of PMMA into an underlying silicon substrate causes latent damage in the resist. On development of the resist we demonstrate the formation within the PMMA layer of clearly defined etched holes, of typical diameter 30 nm, observed using an atomic force microscope employing a carbon nanotube SPM probe in intermittent-contact mode. This technique has significant potential applications. Used purely to register the passage of an ion, it may be a useful verification of the impact sites in an ion-beam modification process operating at the single-ion level. Furthermore, making use of the hole in the PMMA layer to perform subsequent fabrication steps, it may be applied to the fabrication of self-aligned structures in which surface features are fabricated directly above regions of an underlying substrate that are locally doped by the implanted ion. Our primary interest in single-ion resists relates to the development of a solid-state quantum computer based on an array of 31P atoms (which act as qubits) embedded with nanoscale precision in a silicon matrix. One proposal for the fabrication of such an array is by phosphorous-ion implantation. A single-ion resist would permit an accurate verification of 31P implantation sites. Subsequent metalisation of the latent damage may allow the fabrication of self-aligned metal gates above buried phosphorous atoms.

High-precision, large-domain three-dimensional manipulation of nano-materials for fabrication nanodevices

PubMed Central

2011-01-01

Nanoscaled materials are attractive building blocks for hierarchical assembly of functional nanodevices, which exhibit diverse performances and simultaneous functions. We innovatively fabricated semiconductor nano-probes of tapered ZnS nanowires through melting and solidifying by electro-thermal process; and then, as-prepared nano-probes can manipulate nanomaterials including semiconductor/metal nanowires and nanoparticles through sufficiently electrostatic force to the desired location without structurally and functionally damage. With some advantages of high precision and large domain, we can move and position and interconnect individual nanowires for contracting nanodevices. Interestingly, by the manipulating technique, the nanodevice made of three vertically interconnecting nanowires, i.e., diode, was realized and showed an excellent electrical property. This technique may be useful to fabricate electronic devices based on the nanowires' moving, positioning, and interconnecting and may overcome fundamental limitations of conventional mechanical fabrication. PMID:21794151

Precision process calibration and CD predictions for low-k1 lithography

NASA Astrophysics Data System (ADS)

Chen, Ting; Park, Sangbong; Berger, Gabriel; Coskun, Tamer H.; de Vocht, Joep; Chen, Fung; Yu, Linda; Hsu, Stephen; van den Broeke, Doug; Socha, Robert; Park, Jungchul; Gronlund, Keith; Davis, Todd; Plachecki, Vince; Harris, Tom; Hansen, Steve; Lambson, Chuck

2005-06-01

Leading resist calibration for sub-0.3 k1 lithography demands accuracy <2nm for CD through pitch. An accurately calibrated resist process is the prerequisite for establishing production-worthy manufacturing under extreme low k1. From an integrated imaging point of view, the following key components must be simultaneously considered during the calibration - high numerical aperture (NA>0.8) imaging characteristics, customized illuminations (measured vs. modeled pupil profiles), resolution enhancement technology (RET) mask with OPC, reticle metrology, and resist thin film substrate. For imaging at NA approaching unity, polarized illumination can impact significantly the contrast formation in the resist film stack, and therefore it is an important factor to consider in the CD-based resist calibration. For aggressive DRAM memory core designs at k1<0.3, pattern-specific illumination optimization has proven to be critical for achieving the required imaging performance. Various optimization techniques from source profile optimization with fixed mask design to the combined source and mask optimization have been considered for customer designs and available imaging capabilities. For successful low-k1 process development, verification of the optimization results can only be made with a sufficiently tunable resist model that can predicate the wafer printing accurately under various optimized process settings. We have developed, for resist patterning under aggressive low-k1 conditions, a novel 3D diffusion model equipped with double-Gaussian convolution in each dimension. Resist calibration with the new diffusion model has demonstrated a fitness and CD predication accuracy that rival or outperform the traditional 3D physical resist models. In this work, we describe our empirical approach to achieving the nm-scale precision for advanced lithography process calibrations, using either measured 1D CD through-pitch or 2D memory core patterns. We show that for ArF imaging, the

Versatile fabrication of paper-based microfluidic devices with high chemical resistance using scholar glue and magnetic masks.

PubMed

Cardoso, Thiago M G; de Souza, Fabrício R; Garcia, Paulo T; Rabelo, Denilson; Henry, Charles S; Coltro, Wendell K T

2017-06-29

Simple methods have been developed for fabricating microfluidic paper-based analytical devices (μPADs) but few of these devices can be used with organic solvents and/or aqueous solutions containing surfactants. This study describes a simple fabrication strategy for μPADs that uses readily available scholar glue to create the hydrophobic flow barriers that are resistant to surfactants and organic solvents. Microfluidic structures were defined by magnetic masks designed with either neodymium magnets or magnetic sheets to define the patter, and structures were created by spraying an aqueous solution of glue on the paper surface. The glue-coated paper was then exposed to UV/Vis light for cross-linking to maximize chemical resistance. Examples of microzone arrays and microfluidic devices are demonstrated. μPADs fabricated with scholar glue retained their barriers when used with surfactants, organic solvents, and strong/weak acids and bases unlike common wax-printed barriers. Paper microzones and microfluidic devices were successfully used for colorimetric assays of clinically relevant analytes commonly detected in urinalysis to demonstrate the low background of the barrier material and generally applicability to sensing. The proposed fabrication method is attractive for both its ability to be used with diverse chemistries and the low cost and simplicity of the materials and process. Copyright © 2017 Elsevier B.V. All rights reserved.

3D printing scanning electron microscopy sample holders: A quick and cost effective alternative for custom holder fabrication.

PubMed

Meloni, Gabriel N; Bertotti, Mauro

2017-01-01

A simple and cost effective alternative for fabricating custom Scanning Electron Microscope (SEM) sample holders using 3D printers and conductive polylactic acid filament is presented. The flexibility of the 3D printing process allowed for the fabrication of sample holders with specific features that enable the high-resolution imaging of nanoelectrodes and nanopipettes. The precise value of the inner semi cone angle of the nanopipettes taper was extracted from the acquired images and used for calculating their radius using electrochemical methods. Because of the low electrical resistivity presented by the 3D printed holder, the imaging of non-conductive nanomaterials, such as alumina powder, was found to be possible. The fabrication time for each sample holder was under 30 minutes and the average cost was less than $0.50 per piece. Despite being quick and economical to fabricate, the sample holders were found to be sufficiently resistant, allowing for multiple uses of the same holder.

3D printing scanning electron microscopy sample holders: A quick and cost effective alternative for custom holder fabrication

PubMed Central

Bertotti, Mauro

2017-01-01

A simple and cost effective alternative for fabricating custom Scanning Electron Microscope (SEM) sample holders using 3D printers and conductive polylactic acid filament is presented. The flexibility of the 3D printing process allowed for the fabrication of sample holders with specific features that enable the high-resolution imaging of nanoelectrodes and nanopipettes. The precise value of the inner semi cone angle of the nanopipettes taper was extracted from the acquired images and used for calculating their radius using electrochemical methods. Because of the low electrical resistivity presented by the 3D printed holder, the imaging of non-conductive nanomaterials, such as alumina powder, was found to be possible. The fabrication time for each sample holder was under 30 minutes and the average cost was less than $0.50 per piece. Despite being quick and economical to fabricate, the sample holders were found to be sufficiently resistant, allowing for multiple uses of the same holder. PMID:28753638

Development of autoclavable polyimides. [fabrication procedures of high temperature resistant/fiber composite

NASA Technical Reports Server (NTRS)

Orell, M. K.; Sheppard, C. H.; Vaughan, R. W.; Jones, R. J.

1974-01-01

A poly(Diels-Alder) (PDA) resin approach was investigated as a means to achieve autoclavability of high temperature resistant resin/fiber composites under mild fabrication procedures. Low void content Type A-S graphite reinforced composites were autoclave fabricated from a PDA resin/fiber prepared from an acetone:methanol:dioxane varnish. Autoclave conditions were 477K (400F) and 0.7 MN/sq m (100 psi) for up to two hours duration. After postcure at temperatures up to 589K (600F), the composites demonstrated high initial mechanical properties at temperatures up to 561K (550F). The results from isothermal aging studies in air for 1000 hours indicated potential for long-term ( 1000 hours) use at 533K (500F) and shorter-term (up to 1000 hours) at 561K (550F).

Fabrication and Assembly of High-Precision Hinge and Latch Joints for Deployable Optical Instruments

NASA Technical Reports Server (NTRS)

Phelps, James E.

1999-01-01

Descriptions are presented of high-precision hinge and latch joints that have been co-developed, for application to deployable optical instruments, by NASA Langley Research Center and Nyma/ADF. Page-sized versions of engineering drawings are included in two appendices to describe all mechanical components of both joints. Procedures for assembling the mechanical components of both joints are also presented. The information herein is intended to facilitate the fabrication and assembly of the high-precision hinge and latch joints, and enable the incorporation of these joints into the design of deployable optical instrument systems.

Fabrication of Subnanometer-Precision Nanopores in Hexagonal Boron Nitride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilbert, S. Matt; Dunn, Gabriel; Azizi, Amin

Here, we demonstrate the fabrication of individual nanopores in hexagonal boron nitride (h-BN) with atomically precise control of the pore shape and size. Previous methods of pore production in other 2D materials typically create pores with irregular geometry and imprecise diameters. In contrast, other studies have shown that with careful control of electron irradiation, defects in h-BN grow with pristine zig-zag edges at quantized triangular sizes, but they have failed to demonstrate production and control of isolated defects. In this work, we combine these techniques to yield a method in which we can create individual size-quantized triangular nanopores through anmore » h-BN sheet. The pores are created using the electron beam of a conventional transmission electron microscope; which can strip away multiple layers of h-BN exposing single-layer regions, introduce single vacancies, and preferentially grow vacancies only in the single-layer region. We further demonstrate how the geometry of these pores can be altered beyond triangular by changing beam conditions. Precisely size- and geometry-tuned nanopores could find application in molecular sensing, DNA sequencing, water desalination, and molecular separation.« less

Fabrication of Subnanometer-Precision Nanopores in Hexagonal Boron Nitride

DOE PAGES

Gilbert, S. Matt; Dunn, Gabriel; Azizi, Amin; ...

2017-11-08

Here, we demonstrate the fabrication of individual nanopores in hexagonal boron nitride (h-BN) with atomically precise control of the pore shape and size. Previous methods of pore production in other 2D materials typically create pores with irregular geometry and imprecise diameters. In contrast, other studies have shown that with careful control of electron irradiation, defects in h-BN grow with pristine zig-zag edges at quantized triangular sizes, but they have failed to demonstrate production and control of isolated defects. In this work, we combine these techniques to yield a method in which we can create individual size-quantized triangular nanopores through anmore » h-BN sheet. The pores are created using the electron beam of a conventional transmission electron microscope; which can strip away multiple layers of h-BN exposing single-layer regions, introduce single vacancies, and preferentially grow vacancies only in the single-layer region. We further demonstrate how the geometry of these pores can be altered beyond triangular by changing beam conditions. Precisely size- and geometry-tuned nanopores could find application in molecular sensing, DNA sequencing, water desalination, and molecular separation.« less

Fabrication of micro metallic valve and pump

NASA Astrophysics Data System (ADS)

Yang, Ming; Kabasawa, Yasunari; Ito, Kuniyoshi

2010-03-01

Fabrication of micro devices by using micro metal forming was proposed by the authors. We developed a desktop servo-press machine with precise tooling system. Precise press forming processes including micro forging and micro joining has been carried out in a progressive die. In this study, micro metallic valve and pump were fabricated by using the precise press forming. The components are made of sheet metals, and assembled in to a unit in the progressive die. A micro check-valve with a diameter of 3mm and a length of 3.2mm was fabricated, and the property of flow resistance was evaluated. The results show that the check valve has high property of leakage proof. Since the valve is a unit parts with dimensions of several millimeters, it has advantage to be adapted to various pump design. Here, two kinds of micro pumps with the check-valves were fabricated. One is diaphragm pump actuated by vibration of the diaphragm, and another is tube-shaped pump actuated by resonation. The flow quantities of the pumps were evaluated and the results show that both of the pumps have high pumping performance.

A precision analogue integrator system for heavy current measurement in MFDC resistance spot welding

NASA Astrophysics Data System (ADS)

Xia, Yu-Jun; Zhang, Zhong-Dian; Xia, Zhen-Xin; Zhu, Shi-Liang; Zhang, Rui

2016-02-01

In order to control and monitor the quality of middle frequency direct current (MFDC) resistance spot welding (RSW), precision measurement of the welding current up to 100 kA is required, for which Rogowski coils are the only viable current transducers at present. Thus, a highly accurate analogue integrator is the key to restoring the converted signals collected from the Rogowski coils. Previous studies emphasised that the integration drift is a major factor that influences the performance of analogue integrators, but capacitive leakage error also has a significant impact on the result, especially in long-time pulse integration. In this article, new methods of measuring and compensating capacitive leakage error are proposed to fabricate a precision analogue integrator system for MFDC RSW. A voltage holding test is carried out to measure the integration error caused by capacitive leakage, and an original integrator with a feedback adder is designed to compensate capacitive leakage error in real time. The experimental results and statistical analysis show that the new analogue integrator system could constrain both drift and capacitive leakage error, of which the effect is robust to different voltage levels of output signals. The total integration error is limited within  ±0.09 mV s-1 0.005% s-1 or full scale at a 95% confidence level, which makes it possible to achieve the precision measurement of the welding current of MFDC RSW with Rogowski coils of 0.1% accuracy class.

Robust and Drain Resistant Lubricated Omniphobic Fabrics

NASA Astrophysics Data System (ADS)

Kido, Cassidee; Damle, Viraj; Sun, Xiaoda; Roopesh, Ajay; Doudrick, Kyle; Rykaczewski, Konrad

2014-11-01

The implications of omniphobic fabrics range from stainproof clothing to civilian and military protection from chemical weapons. The challenge comes in developing a product that remains effective in repelling droplets of liquids with a wide range of surface tensions even after being subjected to various stimuli imposed by human use. Omniphobic fabrics can be made by infusing hydrophobic nanoparticle coated fibers with a low surface energy lubricant. These types of lubricant impregnated surfaces can shed large deposited droplets as well as condensed microdroplets of variety of low surface tension liquids. However, here we show that lubricated omniphobic fabrics can easily lose their properties due to degradation of the nanostructure coating or drainage of the lubricant upon contact with a porous surface. We also demonstrate that this issue can be resolved with use of cross-linked polymer coated fibers that are swollen with the lubricant. Use of flexible polymers avoids structure degradation due to fabric deformation, while swelling of the polymer with lubricant minimizes lubricant drainage upon contact maintaining the omniphobic characteristics of the fabric. KR acknowledges startup funding from ASU and collaborative effort with Dr. Tim Burgin and James R. Lee from Naval Surface Warfare Center Dahlgren Division.

Development and fabrication of low ON resistance high current vertical VMOS power FETs

NASA Technical Reports Server (NTRS)

Kay, S.

1979-01-01

The design of a VMOS Power FET exhibiting low ON resistance, high current as well as high breakdown voltage and fast switching speeds is described. The design which is based on a 1st-order device model, features a novel polysilicon-gate structure and fieldplated groove termination to achieve high packing density and high breakdown voltage, respectively. One test chip, named VNTKI, can block 180 V at an ON resistence of 2.5 ohm. A 150 mil x 200 mil (.19 sq cm) experimental chip has demonstrated a breakdown voltage of 200v, an ON resistance of 0.12 ohm, a switching time of less than 100 ns, and a pulse drain - current of 50 A with 10 V gate drive.

High-efficiency (6 + 1) × 1 pump-signal combiner based on low-deformation and high-precision alignment fabrication

NASA Astrophysics Data System (ADS)

Zou, Shuzhen; Chen, Han; Yu, Haijuan; Sun, Jing; Zhao, Pengfei; Lin, Xuechun

2017-12-01

We demonstrate a new method for fabricating a (6 + 1) × 1 pump-signal combiner based on the reduction of signal fiber diameter by corrosion. This method avoids the mismatch loss of the splice between the signal fiber and the output fiber caused by the signal fiber taper processing. The optimum radius of the corroded signal fiber was calculated according to the analysis of the influence of the cladding thickness on the laser propagating in the fiber core. Besides, we also developed a two-step splicing method to complete the high-precision alignment between the signal fiber core and the output fiber core. A high-efficiency (6 + 1) × 1 pump-signal combiner was produced with an average pump power transmission efficiency of 98.0% and a signal power transmission efficiency of 97.7%, which is well suitable for application to high-power fiber laser system.

Study on Single-yarn Pullout Test of Ballistic Resistant Fabric under Different Preloads

NASA Astrophysics Data System (ADS)

Fang, Q. C.; Lei, Z. K.; Y Qin, F.; Li, W. K.; Bai, R. X.

2017-12-01

During bullet penetrating fabric, the pull-out force of yarn in fabric is related to the impact resistance of fabric when the yarn is pulled out from the fabric. The complex uncrimping and friction slip behavior occur during the yarn pullout process, which is critical to learn the impact resistance of fabric. Based on digital image correlation technique, the deformation behavior of Kevlar 49 fabric subjected to preload during the single-yarn pullout process was studied in this paper. The pullout force and displacement curve shows a straight rise and an oscillated decrease. In the linear rise stage, the yarn uncrimping causes a static friction effect. The maximum of the pullout force is not linearly increased with the preload. In the oscillating descending stage, the local descent of the pullout force indicates that the yarn end is gradually withdrawn from the fabric, and the local rise indicates that the yarn end moves to the next weft/warp interaction until the yarn is completely pulled out. The shear deformation of fabric corresponds to the single-yarn pullout process.

Preparation of silver nanoparticles fabrics against multidrug-resistant bacteria

NASA Astrophysics Data System (ADS)

Hanh, Truong Thi; Thu, Nguyen Thi; Hien, Nguyen Quoc; An, Pham Ngoc; Loan, Truong Thi Kieu; Hoa, Phan Thi

2016-04-01

The silver nanoparticles (AgNPs)/peco fabrics were prepared by immobilization of AgNPs on fabrics in which AgNPs were synthesized by γ-irradiation of the 10 mM AgNO3 chitosan solution at the dose of 17.6 kGy. The AgNPs size has been estimated to be about 11 nm from TEM image. The AgNPs content onto peco fabrics was of 143±6 mg/kg at the initial AgNPs concentration of 100 ppm. The AgNPs colloidal solution was characterized by UV-vis spectroscopy and TEM image. The antibacterial activity of AgNPs/peco fabrics after 60 washings against Staphylococcus aureus and Klebsiella pneumoniae was found to be over 99%. Effects of AgNPs fabics on multidrug-resistant pathogens from the clinical specimens were also tested.

Microchannel plate fabrication using glass capillary arrays with Atomic Layer Deposition films for resistance and gain

NASA Astrophysics Data System (ADS)

Popecki, M. A.; Adams, B.; Craven, C. A.; Cremer, T.; Foley, M. R.; Lyashenko, A.; O'Mahony, A.; Minot, M. J.; Aviles, M.; Bond, J. L.; Stochaj, M. E.; Worstell, W.; Elam, J. W.; Mane, A. U.; Siegmund, O. H. W.; Ertley, C.; Kistler, L. M.; Granoff, M. S.

2016-08-01

Microchannel plates (MCPs) have been used for many years in space flight instrumentation as fast, lightweight electron multipliers. A new MCP fabrication method combines a glass substrate composed of hollow glass capillary arrays with thin film coatings to provide the resistive and secondary electron emissive properties. Using this technique, the gain, resistance, and glass properties may be chosen independently. Large-area MCPs are available at moderate cost. Secondary emission films of Al2O3 and MgO provide sustained high gain as charge is extracted from the MCP. Long lifetimes are possible, and a total extracted charge of 7 C/cm2 has been demonstrated. Background rates are low because the glass substrate has little radioactive potassium 40. Curved MCPs are easily fabricated with this technique to suit instrument symmetries, simplifying secondary electron steering and smoothing azimuthal efficiency.

Fabrication of cross-shaped Cu-nanowire resistive memory devices using a rapid, scalable, and designable inorganic-nanowire-digital-alignment technique (Conference Presentation)

NASA Astrophysics Data System (ADS)

Xu, Wentao; Lee, Yeongjun; Min, Sung-Yong; Park, Cheolmin; Lee, Tae-Woo

2016-09-01

Resistive random-access memory (RRAM) is a candidate next generation nonvolatile memory due to its high access speed, high density and ease of fabrication. Especially, cross-point-access allows cross-bar arrays that lead to high-density cells in a two-dimensional planar structure. Use of such designs could be compatible with the aggressive scaling down of memory devices, but existing methods such as optical or e-beam lithographic approaches are too complicated. One-dimensional inorganic nanowires (i-NWs) are regarded as ideal components of nanoelectronics to circumvent the limitations of conventional lithographic approaches. However, post-growth alignment of these i-NWs precisely on a large area with individual control is still a difficult challenge. Here, we report a simple, inexpensive, and rapid method to fabricate two-dimensional arrays of perpendicularly-aligned, individually-conductive Cu-NWs with a nanometer-scale CuxO layer sandwiched at each cross point, by using an inorganic-nanowire-digital-alignment technique (INDAT) and a one-step reduction process. In this approach, the oxide layer is self-formed and patterned, so conventional deposition and lithography are not necessary. INDAT eliminates the difficulties of alignment and scalable fabrication that are encountered when using currently-available techniques that use inorganic nanowires. This simple process facilitates fabrication of cross-point nonvolatile memristor arrays. Fabricated arrays had reproducible resistive switching behavior, high on/off current ratio (Ion/Ioff) 10 6 and extensive cycling endurance. This is the first report of memristors with the resistive switching oxide layer self-formed, self-patterned and self-positioned; we envision that the new features of the technique will provide great opportunities for future nano-electronic circuits.

Fabrication of Nano-Crossbar Resistive Switching Memory Based on the Copper-Tantalum Pentoxide-Platinum Device Structure

NASA Astrophysics Data System (ADS)

Olga Gneri, Paula; Jardim, Marcos

Resistive switching memory has been of interest lately not only for its simple metal-insulator-metal (MIM) structure but also for its promising ease of scalability an integration into current CMOS technologies like the Field Programmable Gate Arrays and other non-volatile memory applications. There are several resistive switching MIM combinations but under this scope of research, attention will be paid to the bipolar resistive switching characteristics and fabrication of Tantalum Pentaoxide sandwiched between platinum and copper. By changing the polarity of the voltage bias, this metal-insulator-metal (MIM) device can be switched between a high resistive state (OFF) and low resistive state (ON). The change in states is induced by an electrochemical metallization process, which causes a formation or dissolution of Cu metal filamentary paths in the Tantalum Pentaoxide insulator. There is very little thorough experimental information about the Cu-Ta 2O5-Pt switching characteristics when scaled to nanometer dimensions. In this light, the MIM structure was fabricated in a two-dimensional crossbar format. Also, with the limited available resources, a multi-spacer technique was formulated to localize the active device area in this MIM configuration to less than 20nm. This step is important in understanding the switching characteristics and reliability of this structure when scaled to nanometer dimensions.

Heat sealable, flame and abrasion resistant coated fabric

NASA Technical Reports Server (NTRS)

Tschirch, R. P.; Sidman, K. R. (Inventor)

1983-01-01

Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.

Fabrication of an infrared Shack-Hartmann sensor by combining high-speed single-point diamond milling and precision compression molding processes.

PubMed

Zhang, Lin; Zhou, Wenchen; Naples, Neil J; Yi, Allen Y

2018-05-01

A novel fabrication method by combining high-speed single-point diamond milling and precision compression molding processes for fabrication of discontinuous freeform microlens arrays was proposed. Compared with slow tool servo diamond broaching, high-speed single-point diamond milling was selected for its flexibility in the fabrication of true 3D optical surfaces with discontinuous features. The advantage of single-point diamond milling is that the surface features can be constructed sequentially by spacing the axes of a virtual spindle at arbitrary positions based on the combination of rotational and translational motions of both the high-speed spindle and linear slides. By employing this method, each micro-lenslet was regarded as a microstructure cell by passing the axis of the virtual spindle through the vertex of each cell. An optimization arithmetic based on minimum-area fabrication was introduced to the machining process to further increase the machining efficiency. After the mold insert was machined, it was employed to replicate the microlens array onto chalcogenide glass. In the ensuing optical measurement, the self-built Shack-Hartmann wavefront sensor was proven to be accurate in detecting an infrared wavefront by both experiments and numerical simulation. The combined results showed that precision compression molding of chalcogenide glasses could be an economic and precision optical fabrication technology for high-volume production of infrared optics.

SOLARIS 3-axis high load, low profile, high precision motorized positioner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acome, Eric; Van Every, Eric; Deyhim, Alex, E-mail: adc@adc9001.com

A 3-axis optical table, shown in Figure 1, was designed, fabricated, and assembled for the SOLARIS synchrotron facility at the Jagiellonian University in Krakow, Poland. To accommodate the facility, the table was designed to be very low profile, as seen in Figure 2, and bear a high load. The platform has degrees of freedom in the vertical (Z) direction as well as horizontal transversal (X and Y) directions. The table is intended to sustain loads as large as 1500 kg which will be sufficient to support a variety of equipment to measure and facilitate synchrotron radiation. After assembly, the tablemore » was tested and calibrated to find its position error in the vertical direction. ADC has extensive experience designing and building custom complex high precision motion systems [1,2].« less

Low-power resistive random access memory by confining the formation of conducting filaments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yi-Jen; Lee, Si-Chen, E-mail: sclee@ntu.edu.tw; Shen, Tzu-Hsien

2016-06-15

Owing to their small physical size and low power consumption, resistive random access memory (RRAM) devices are potential for future memory and logic applications in microelectronics. In this study, a new resistive switching material structure, TiO{sub x}/silver nanoparticles/TiO{sub x}/AlTiO{sub x}, fabricated between the fluorine-doped tin oxide bottom electrode and the indium tin oxide top electrode is demonstrated. The device exhibits excellent memory performances, such as low operation voltage (<±1 V), low operation power, small variation in resistance, reliable data retention, and a large memory window. The current-voltage measurement shows that the conducting mechanism in the device at the high resistancemore » state is via electron hopping between oxygen vacancies in the resistive switching material. When the device is switched to the low resistance state, conducting filaments are formed in the resistive switching material as a result of accumulation of oxygen vacancies. The bottom AlTiO{sub x} layer in the device structure limits the formation of conducting filaments; therefore, the current and power consumption of device operation are significantly reduced.« less

Fabrication of high precision metallic freeform mirrors with magnetorheological finishing (MRF)

NASA Astrophysics Data System (ADS)

Beier, Matthias; Scheiding, Sebastian; Gebhardt, Andreas; Loose, Roman; Risse, Stefan; Eberhardt, Ramona; Tünnermann, Andreas

2013-09-01

The fabrication of complex shaped metal mirrors for optical imaging is a classical application area of diamond machining techniques. Aspherical and freeform shaped optical components up to several 100 mm in diameter can be manufactured with high precision in an acceptable amount of time. However, applications are naturally limited to the infrared spectral region due to scatter losses for shorter wavelengths as a result of the remaining periodic diamond turning structure. Achieving diffraction limited performance in the visible spectrum demands for the application of additional polishing steps. Magnetorheological Finishing (MRF) is a powerful tool to improve figure and finish of complex shaped optics at the same time in a single processing step. The application of MRF as a figuring tool for precise metal mirrors is a nontrivial task since the technology was primarily developed for figuring and finishing a variety of other optical materials, such as glasses or glass ceramics. In the presented work, MRF is used as a figuring tool for diamond turned aluminum lightweight mirrors with electroless nickel plating. It is applied as a direct follow-up process after diamond machining of the mirrors. A high precision measurement setup, composed of an interferometer and an advanced Computer Generated Hologram with additional alignment features, allows for precise metrology of the freeform shaped optics in short measuring cycles. Shape deviations less than 150 nm PV / 20 nm rms are achieved reliably for freeform mirrors with apertures of more than 300 mm. Characterization of removable and induced spatial frequencies is carried out by investigating the Power Spectral Density.

Micro Machining Enhances Precision Fabrication

NASA Technical Reports Server (NTRS)

2007-01-01

Advanced thermal systems developed for the Space Station Freedom project are now in use on the International Space Station. These thermal systems employ evaporative ammonia as their coolant, and though they employ the same series of chemical reactions as terrestrial refrigerators, the space-bound coolers are significantly smaller. Two Small Business Innovation Research (SBIR) contracts between Creare Inc. of Hanover, NH and Johnson Space Center developed an ammonia evaporator for thermal management systems aboard Freedom. The principal investigator for Creare Inc., formed Mikros Technologies Inc. to commercialize the work. Mikros Technologies then developed an advanced form of micro-electrical discharge machining (micro-EDM) to make tiny holes in the ammonia evaporator. Mikros Technologies has had great success applying this method to the fabrication of micro-nozzle array systems for industrial ink jet printing systems. The company is currently the world leader in fabrication of stainless steel micro-nozzles for this market, and in 2001 the company was awarded two SBIR research contracts from Goddard Space Flight Center to advance micro-fabrication and high-performance thermal management technologies.

Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo.

PubMed

Zhao, Bingjing; Wang, Hong; Qiao, Ning; Wang, Chao; Hu, Min

2017-01-01

The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (<1.5V) and EBM specimen was the best under the high electric potential (>1.5V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrofluoric acid-resistant composite window and method for its fabrication

DOEpatents

Ostenak, C.A.; Mackay, H.A.

1985-07-18

A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

Hydrofluoric acid-resistant composite window and method for its fabrication

DOEpatents

Ostenak, Carl A.; Mackay, Harold A.

1987-01-01

A hydrofluoric acid-resistant composite window and method for its fabrication are disclosed. The composite window comprises a window having first and second sides. The first side is oriented towards an environment containing hydrofluoric acid. An adhesive is applied to the first side. A layer of transparent hydrofluoric acid-resistant material, such as Mylar, is applied to the adhesive and completely covers the first side. The adhesive is then cured.

Shop fabricated corrosion-resistant underground storage tanks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geyer, W.B.; Stellmach, W.A.

1995-12-31

Integral corrosion resistance has long been incorporated into shop fabricated steel underground storage tank design. Since 1969, an industry standard has been the sti-P{sub 3}{reg_sign} (P3) tank. However, the past decade has seen the development of several alternative corrosion resistant and secondary containment technologies. Fiberglass-coated steel composite tanks, and jacketed tanks utilizing various materials as a secondary wall, provide corrosion resistance without the cathodic protection monitoring requirements mandated by the EPA for single-wall P3 tanks. On the other hand, the P3 tank is the only tank technology commonly marketed today with an integral ability to verify its corrosion resistance overmore » the life of the tank. Many existing USTs remain to be replaced or upgraded with corrosion resistance (and other requirements) by the end of 1998. Steel tanks built and installed prior to the advent of pre-engineered, factory-supplied protection against corrosion can be retrofitted with cathodic protection or can be internally lined. Specific installation standards developed by the steel tank industry and the petroleum industry must be followed so as to assure the integrity of the various corrosion resistant technologies developed by the Steel Tank Institute. The technologies describes in this paper will ensure compliance with the corrosion protection requirements of new storage tanks.« less

Design and fabrication of low power GaAs/AlAs resonant tunneling diodes

NASA Astrophysics Data System (ADS)

Md Zawawi, Mohamad Adzhar; Missous, Mohamed

2017-12-01

A very low peak voltage GaAs/AlAs resonant tunneling diode (RTD) grown by molecular beam epitaxy (MBE) has been studied in detail. Excellent growth control with atomic-layer precision resulted in a peak voltage of merely 0.28 V (0.53 V) in forward (reverse) direction. The peak current density in forward bias is around 15.4 kA/cm2 with variation of within 7%. As for reverse bias, the peak current density is around 22.8 kA/cm2 with 4% variation which implies excellent scalability. In this work, we have successfully demonstrated the fabrication of a GaAs/AlAs RTD by using a conventional optical lithography and chemical wet-etching with very low peak voltage suitable for application in low dc input power RTD-based sub-millimetre wave oscillators.

Strength and flexibility properties of advanced ceramic fabrics

NASA Technical Reports Server (NTRS)

Sawko, P. M.; Tran, H. K.

1985-01-01

The mechanical properties of four advanced ceramic fabrics were measured at a temperature range of 23C to 1200C. The fabrics evaluated were silica, high and low-boria content aluminoborosilicate, and silicon carbide. Properties studied included fabric break strengths from room temperature to 1200C, and bending durability after temperature conditioning at 1200C and 1400C. The interaction of the fabric and ceramic insulation was also studied for shrinkage, appearance, bend resistance, and fabric-to-insulation bonding. Based on these tests, the low-boria content aluminoborosilicate fabric retained more strength and fabric durability than the other fabrics studied at high temperature.

Strength and flexibility properties of advanced ceramic fabrics

NASA Technical Reports Server (NTRS)

Sawko, P. M.; Tran, H. K.

1985-01-01

The mechanical properties of four advanced ceramic fabrics are measured at a temperature range of 23 C to 1200 C. The fabrics evaluated are silica, high-and low-boria content aluminoborosilicate, and silicon carbide. Properties studied include fabric break strengths from room temperature to 1200 C, and bending durability after temperature conditioning at 1200 C and 1400 C. The interaction of the fabric and ceramic insulation is also studied for shrinkage, appearance, bend resistance, and fabric-to-insulation bonding. Based on these tests, the low-boria content aluminoborosilicate fabric retains more strength and fabric durability than the other fabrics studied at high temperature.

Design of Low-Noise Output Amplifiers for P-channel Charge-Coupled Devices Fabricated on High-Resistivity Silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haque, S; Frost, F Dion R.; Groulx, R

2011-12-22

We describe the design and optimization of low-noise, single-stage output amplifiers for p-channel charge-coupled devices (CCDs) used for scientific applications in astronomy and other fields. The CCDs are fabricated on high-resistivity, 4000–5000 -cm, n-type silicon substrates. Single-stage amplifiers with different output structure designs and technologies have been characterized. The standard output amplifier is designed with an n{sup +} polysilicon gate that has a metal connection to the sense node. In an effort to lower the output amplifier readout noise by minimizing the capacitance seen at the sense node, buried-contact technology has been investigated. In this case, the output transistor hasmore » a p{sup +} polysilicon gate that connects directly to the p{sup +} sense node. Output structures with buried-contact areas as small as 2 μm × 2 μm are characterized. In addition, the geometry of the source-follower transistor was varied, and we report test results on the conversion gain and noise of the various amplifier structures. By use of buried-contact technology, better amplifier geometry, optimization of the amplifier biases and improvements in the test electronics design, we obtain a 45% reduction in noise, corresponding to 1.7 e{sup -} rms at 70 kpixels/sec.« less

Fabrication of thermal-resistant gratings for high-temperature measurements using geometric phase analysis.

PubMed

Zhang, Q; Liu, Z; Xie, H; Ma, K; Wu, L

2016-12-01

Grating fabrication techniques are crucial to the success of grating-based deformation measurement methods because the quality of the grating will directly affect the measurement results. Deformation measurements at high temperatures entail heating and, perhaps, oxidize the grating. The contrast of the grating lines may change during the heating process. Thus, the thermal-resistant capability of the grating becomes a point of great concern before taking measurements. This study proposes a method that combines a laser-engraving technique with the processes of particle spraying and sintering for fabricating thermal-resistant gratings. The grating fabrication technique is introduced and discussed in detail. A numerical simulation with a geometric phase analysis (GPA) is performed for a homogeneous deformation case. Then, the selection scheme of the grating pitch is suggested. The validity of the proposed technique is verified by fabricating a thermal-resistant grating on a ZrO 2 specimen and measuring its thermal strain at high temperatures (up to 1300 °C). Images of the grating before and after deformation are used to obtain the thermal-strain field by GPA and to compare the results with well-established reference data. The experimental results indicate that this proposed technique is feasible and will offer good prospects for further applications.

Understanding and Optimizing Asynchronous Low-Precision Stochastic Gradient Descent

PubMed Central

De Sa, Christopher; Feldman, Matthew; Ré, Christopher; Olukotun, Kunle

2018-01-01

Stochastic gradient descent (SGD) is one of the most popular numerical algorithms used in machine learning and other domains. Since this is likely to continue for the foreseeable future, it is important to study techniques that can make it run fast on parallel hardware. In this paper, we provide the first analysis of a technique called Buckwild! that uses both asynchronous execution and low-precision computation. We introduce the DMGC model, the first conceptualization of the parameter space that exists when implementing low-precision SGD, and show that it provides a way to both classify these algorithms and model their performance. We leverage this insight to propose and analyze techniques to improve the speed of low-precision SGD. First, we propose software optimizations that can increase throughput on existing CPUs by up to 11×. Second, we propose architectural changes, including a new cache technique we call an obstinate cache, that increase throughput beyond the limits of current-generation hardware. We also implement and analyze low-precision SGD on the FPGA, which is a promising alternative to the CPU for future SGD systems. PMID:29391770

Highly conductive metal interconnects on three-dimensional objects fabricated with omnidirectional ink jet printing technology

NASA Astrophysics Data System (ADS)

Yoshida, Yasunori; Wada, Hikaru; Izumi, Konami; Tokito, Shizuo

2017-05-01

In this work, we demonstrate that highly conductive metal interconnects can be fabricated on the surface of three-dimensional objects using “omnidirectional ink jet” (OIJ) printing technology. OIJ printing technology makes it possible to perform ink jet printing in all directions by combining the motion of a 6-axis vertically articulated robot with precise positioning and a thermal drying process, which allows for the printing of stacked layers. By using OIJ technology, we were the first to successfully fabricate printed interconnect layers having a very low electrical resistance of 12 mΩ over a 10 mm length. Moreover, the results of the high-current test demonstrated that the printed interconnects can withstand high-current-flow of 5 A for 30 min or more.

Dwindling the resistance value of PEDOT:PSS – coated on fabric yarns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amba Sankar, K.N., E-mail: amb@psgias.ac.in; Kallol, Mohanta

2016-05-23

Herein we describe by dip coating method to transform typical fabric yarn to conductive fiber. Different types of yarns have been used to coat from a known conductive polymer, Poly (3,4ethylenedioxythiophene) Poly (styrene sulfonic acid). We have optimized the method to have lesser resistance of the conductive yarns. The minimum resistance achieved has a value of 77 Ω/cm. This value is not high as metals but could be comparable to that of metal oxides or semiconducting materials. However, flexibility of yarns and feeling of fabric combining with the conductivity developed in this process is suitable for wearable electronics and alsomore » as gas sensors, electromagnetic shielding.« less

Application of Matrix Projection Exposure Using a Liquid Crystal Display Panel to Fabricate Thick Resist Molds

NASA Astrophysics Data System (ADS)

Fukasawa, Hirotoshi; Horiuchi, Toshiyuki

2009-08-01

The patterning characteristics of matrix projection exposure using an analog liquid crystal display (LCD) panel in place of a reticle were investigated, in particular for oblique patterns. In addition, a new method for fabricating practical thick resist molds was developed. At first, an exposure system fabricated in past research was reconstructed. Changes in the illumination optics and the projection lens were the main improvements. Using fly's eye lenses, the illumination light intensity distribution was homogenized. The projection lens was changed from a common camera lens to a higher-grade telecentric lens. In addition, although the same metal halide lamp was used as an exposure light source, the central exposure wavelength was slightly shortened from 480 to 450 nm to obtain higher resist sensitivity while maintaining almost equivalent contrast between black and white. Circular and radial patterns with linewidths of approximately 6 µm were uniformly printed in all directions throughout the exposure field owing to these improvements. The patterns were smoothly printed without accompanying stepwise roughness caused by the cell matrix array. On the bases of these results, a new method of fabricating thick resist molds for electroplating was investigated. It is known that thick resist molds fabricated using the negative resist SU-8 (Micro Chem) are useful because very high aspect patterns are printable and the side walls are perpendicular to the substrate surfaces. However, the most suitable exposure wavelength of SU-8 is 365 nm, and SU-8 is insensitive to light of 450 nm wavelength, which is most appropriate for LCD matrix exposure. For this reason, a novel multilayer resist process was proposed, and micromolds of SU-8 of 50 µm thickness were successfully obtained. As a result, feasibility for fabricating complex resist molds including oblique patterns was demonstrated.

Low-cost optical fabrication of flexible copper electrode via laser-induced reductive sintering and adhesive transfer

NASA Astrophysics Data System (ADS)

Back, Seunghyun; Kang, Bongchul

2018-02-01

Fabricating copper electrodes on heat-sensitive polymer films in air is highly challenging owing to the need of expensive copper nanoparticles, rapid oxidation of precursor during sintering, and limitation of sintering temperature to prevent the thermal damage of the polymer film. A laser-induced hybrid process of reductive sintering and adhesive transfer is demonstrated to cost-effectively fabricate copper electrode on a polyethylene film with a thermal resistance below 100 °C. A laser-induced reductive sintering process directly fabricates a high-conductive copper electrode onto a glass donor from copper oxide nanoparticle solution via photo-thermochemical reduction and agglomeration of copper oxide nanoparticles. The sintered copper patterns were transferred in parallel to a heat-sensitive polyethylene film through self-selective surface adhesion of the film, which was generated by the selective laser absorption of the copper pattern. The method reported here could become one of the most important manufacturing technologies for fabricating low-cost wearable and disposable electronics.

Fabrication of precision high quality facets on molecular beam epitaxy material

DOEpatents

Petersen, Holly E.; Goward, William D.; Dijaili, Sol P.

2001-01-01

Fabricating mirrored vertical surfaces on semiconductor layered material grown by molecular beam epitaxy (MBE). Low energy chemically assisted ion beam etching (CAIBE) is employed to prepare mirrored vertical surfaces on MBE-grown III-V materials under unusually low concentrations of oxygen in evacuated etching atmospheres of chlorine and xenon ion beams. UV-stabilized smooth-surfaced photoresist materials contribute to highly vertical, high quality mirrored surfaces during the etching.

Microspheres as resistive elements in a check valve for low pressure and low flow rate conditions.

PubMed

Ou, Kevin; Jackson, John; Burt, Helen; Chiao, Mu

2012-11-07

In this paper we describe a microsphere-based check valve integrated with a micropump. The check valve uses Ø20 μm polystyrene microspheres to rectify flow in low pressure and low flow rate applications (Re < 1). The microspheres form a porous medium in the check valve increasing fluidic resistance based on the direction of flow. Three check valve designs were fabricated and characterized to study the microspheres' effectiveness as resistive elements. A maximum diodicity (ratio of flow in the forward and reverse direction) of 18 was achieved. The pumping system can deliver a minimum flow volume of 0.25 μL and a maximum flow volume of 1.26 μL under an applied pressure of 0.2 kPa and 1 kPa, respectively. A proof-of-concept study was conducted using a pharmaceutical agent, docetaxel (DTX), as a sample drug showing the microsphere check valve's ability to limit diffusion from the micropump. The proposed check valve and pumping concept shows strong potential for implantable drug delivery applications with low flow rate requirements.

Research on the precision measurement of super-low reflectivity

NASA Astrophysics Data System (ADS)

Yuan, Hao-yu; Lu, Zong-gui; Xia, Yan-wen; Peng, Zhi-tao; Liu, Hua; Xu, Long-bo; Sun, Zhi-hong; Tang, Jun

2010-10-01

Introduced a high-precision measurement of measured the super-low reflectivity and small sampling angle. Using single reflect way measured, and compare with re-swatch. Testing the reflectance of the sampling mirror which be used on TIL, and analyze the error. Research results indicate, the main factor which affect result is energy detector error and energy detector linearity. This methods is easy and have high-precision, it can be used to measure the super-low reflectivity sampling mirror reflectance.

Low-resistivity photon-transparent window attached to photo-sensitive silicon detector

DOEpatents

Holland, Stephen Edward

2000-02-15

The invention comprises a combination of a low resistivity, or electrically conducting, silicon layer that is transparent to long or short wavelength photons and is attached to the backside of a photon-sensitive layer of silicon, such as a silicon wafer or chip. The window is applied to photon sensitive silicon devices such as photodiodes, charge-coupled devices, active pixel sensors, low-energy x-ray sensors and other radiation detectors. The silicon window is applied to the back side of a photosensitive silicon wafer or chip so that photons can illuminate the device from the backside without interference from the circuit printed on the frontside. A voltage sufficient to fully deplete the high-resistivity photosensitive silicon volume of charge carriers is applied between the low-resistivity back window and the front, patterned, side of the device. This allows photon-induced charge created at the backside to reach the front side of the device and to be processed by any circuitry attached to the front side. Using the inventive combination, the photon sensitive silicon layer does not need to be thinned beyond standard fabrication methods in order to achieve full charge-depletion in the silicon volume. In one embodiment, the inventive backside window is applied to high resistivity silicon to allow backside illumination while maintaining charge isolation in CCD pixels.

Ecofriendly Fire Retardant and Rot Resistance Finishing of Jute Fabric Using Tin and Boron Based Compound

NASA Astrophysics Data System (ADS)

Samanta, Ashis Kumar; Bagchi, Arindam

2017-06-01

Treatment with sodium stannate followed by treatment with boric acid imparts jute fabric wash fast fire resistance property as indicated by its Limiting Oxygen Index (LOI) value and 45° inclined flammability test results. The treatment was carried out by impregnation of sodium stannate followed by impregnation with an aqueous solution of boric acid and drying. Application of sodium stannate (20%) and boric acid (20%) treatment on jute fabric showed balanced flame retardancy property (LOI value 34) with some loss in fabric tenacity (loss of tenacity is 14.5%). Treated fabric retained good fire retardant property after three consecutive washing. Treated fabric also possessed good rot resistance property as indicated by soil burial test and strength retention after 21 days soil burial was found to be 65%. It is found that of sodium stannate and boric acid combination by double bath process form a synergistic durable fire-retardant as well as rot resistant when impregnated on jute material, which is considerably greater than the use of either sodium stannate or boric acid alone. TGA, FTIR and SEM analysis are also reported to support the results and reaction mechanism.

Magnetometry with Low-Resistance Proximity Josephson Junction

NASA Astrophysics Data System (ADS)

Jabdaraghi, R. N.; Peltonen, J. T.; Golubev, D. S.; Pekola, J. P.

2018-06-01

We characterize a niobium-based superconducting quantum interference proximity transistor (Nb-SQUIPT) and its key constituent formed by a Nb-Cu-Nb SNS weak link. The Nb-SQUIPT and SNS devices are fabricated simultaneously in two separate lithography and deposition steps, relying on Ar ion cleaning of the Nb contact surfaces. The quality of the Nb-Cu interface is characterized by measuring the temperature-dependent equilibrium critical supercurrent of the SNS junction. In the Nb-SQUIPT device, we observe a maximum flux-to-current transfer function value of about 55 nA/Φ_0 in the sub-gap regime of bias voltages. This results in suppression of power dissipation down to a few fW. Low-bias operation of the device with a relatively low probe junction resistance decreases the dissipation by up to two orders of magnitude compared to a conventional device based on an Al-Cu-Al SNS junction and an Al tunnel probe (Al-SQUIPT).

Development of Flame Resistant Combat Uniform Fabrics Made from Long Staple Wool and Aramid Blend Yarn

DTIC Science & Technology

2013-04-15

Kentwool recombed the wool top ( wool is first combed during the production of wool top); a second combing process is an optional step sometimes used in...RESISTANT COMBAT UNIFORM FABRICS MADE FROM LONG STAPLE WOOL AND ARAMID BLEND YARN by Parvez Mehta* Mitchell Driggers* and Carole...SUBTITLE DEVELOPMENT OF FLAME RESISTANT COMBAT UNIFORM FABRICS MADE FROM LONG STAPLE WOOL AND ARAMID BLEND YARN 5a. CONTRACT NUMBER W911QY-11

Fabrication of CFRP/Al Active Laminates

NASA Astrophysics Data System (ADS)

Asanuma, Hiroshi; Haga, Osamu; Ohira, Junichiro; Takemoto, Kyosuke; Imori, Masataka

This paper describes fabrication and evaluation of the active laminate. It was made by hot-pressing of an aluminum plate as a high CTE material, a unidirectional CFRP prepreg as a low CTE material and an electric resistance heater, a KFRP prepreg as a low CTE material and an insulator between them, and copper foils as electrodes. In this study, fabricating conditions and performances such as curvature change and output force were examined. Under optimized fabricating conditions, it became clear that 1) the curvature of the active laminate linearly changes as a function of temperature, between room temperature and its hot pressing temperature without hysteresis by electric resistance heating of carbon fiber in the CFRP layer and cooling, and 2) the output force against a fixed punch almost linearly increases with increasing temperature during heating from 313K up to around the glass transition temperature of the epoxy matrix.

Fabrication and characterization of low temperature polycrystalline silicon thin film transistors

NASA Astrophysics Data System (ADS)

Krishnan, Anand Thiruvengadathan

2000-10-01

The proliferation of devices with built-in displays, such as personal digital assistants and cellular phones has created a demand for rugged light-weight displays. Polymeric substrates could be suited for these applications, and they offer the possibility of flexible displays also. However, driver circuitry needs to be integrated in the display if the cost is to be reduced. Low temperature (<350°C) polycrystalline silicon (poly-Si) thin film transistors, if developed, offer driver circuitry integration during pixel transistor fabrication on top of flexible substrates. This thesis addresses several issues related to the fabrication of thin film transistors at low temperatures on glass substrates. A high-density plasma (electron cyclotron resonance (ECR)) based approach was adopted for deposition of thin films. A process for deposition of n-type doped silicon (n-type doped Si) at T < 350°C and having resistivity <1 ohm/cm has been developed. Intrinsic poly-Si was deposited under different conditions of microwave power, RF bias and deposition times. The properties of n-type doped Si and intrinsic poly-Si were correlated with the structure and the deposition conditions. A novel TFT structure has been proposed and implemented in this work. This top gate TFT structure uses n-type doped Si and utilizes only two masks and one alignment step. There are no critical etch steps and good interface quality could be obtained even without post-processing hydrogenation as the poly-Si surface was not exposed to air before deposition of the gate dielectric. TFTs using this top gate structure were fabricated with no process step exceeding 340°C electrode temperature (surface temperature <300°C). These TFTs show ON/OFF ratios in excess of 105. Their sub-threshold swing is ˜0.5 V/decade and mobility is 1--10 cm2/V-s. Several TFTs were also fabricated using alternative dielectrics such as oxide deposited from tetramethyl silane in an RFPECVD chamber and silicon nitride deposited in

Precision capacitor has improved temperature and operational stability

NASA Technical Reports Server (NTRS)

Brookshier, W. K.; Lewis, R. N.

1967-01-01

Vacuum dielectric capacitor is fabricated from materials with very low temperature coefficients of expansion. This precision capacitor in the 1000-2000 picofarad range has a near-zero temperature coefficient of capacitance, eliminates ion chamber action caused by air ionization in the dielectric, and minimizes electromagnetic field charging effects.

In-process fault detection for textile fabric production: onloom imaging

NASA Astrophysics Data System (ADS)

Neumann, Florian; Holtermann, Timm; Schneider, Dorian; Kulczycki, Ashley; Gries, Thomas; Aach, Til

2011-05-01

Constant and traceable high fabric quality is of high importance both for technical and for high-quality conventional fabrics. Usually, quality inspection is carried out by trained personal, whose detection rate and maximum period of concentration are limited. Low resolution automated fabric inspection machines using texture analysis were developed. Since 2003, systems for the in-process inspection on weaving machines ("onloom") are commercially available. With these defects can be detected, but not measured quantitative precisely. Most systems are also prone to inevitable machine vibrations. Feedback loops for fault prevention are not established. Technology has evolved since 2003: Camera and computer prices dropped, resolutions were enhanced, recording speeds increased. These are the preconditions for real-time processing of high-resolution images. So far, these new technological achievements are not used in textile fabric production. For efficient use, a measurement system must be integrated into the weaving process; new algorithms for defect detection and measurement must be developed. The goal of the joint project is the development of a modern machine vision system for nondestructive onloom fabric inspection. The system consists of a vibration-resistant machine integration, a high-resolution machine vision system, and new, reliable, and robust algorithms with quality database for defect documentation. The system is meant to detect, measure, and classify at least 80 % of economically relevant defects. Concepts for feedback loops into the weaving process will be pointed out.

High-precision and low-cost vibration generator for low-frequency calibration system

NASA Astrophysics Data System (ADS)

Li, Rui-Jun; Lei, Ying-Jun; Zhang, Lian-Sheng; Chang, Zhen-Xin; Fan, Kuang-Chao; Cheng, Zhen-Ying; Hu, Peng-Hao

2018-03-01

Low-frequency vibration is one of the harmful factors that affect the accuracy of micro-/nano-measuring machines because its amplitude is significantly small and it is very difficult to avoid. In this paper, a low-cost and high-precision vibration generator was developed to calibrate an optical accelerometer, which is self-designed to detect low-frequency vibration. A piezoelectric actuator is used as vibration exciter, a leaf spring made of beryllium copper is used as an elastic component, and a high-resolution, low-thermal-drift eddy current sensor is applied to investigate the vibrator’s performance. Experimental results demonstrate that the vibration generator can achieve steady output displacement with frequency range from 0.6 Hz to 50 Hz, an analytical displacement resolution of 3.1 nm and an acceleration range from 3.72 mm s-2 to 1935.41 mm s-2 with a relative standard deviation less than 1.79%. The effectiveness of the high-precision and low-cost vibration generator was verified by calibrating our optical accelerometer.

Plasma-Induced Nonvolatile Resistive Switching with Extremely Low SET Voltage in TiOxFy with AgF Nanoparticles.

PubMed

Sun, Xiangyu; Wu, Chuangui; Shuai, Yao; Pan, Xinqiang; Luo, Wenbo; You, Tiangui; Bogusz, Agnieszka; Du, Nan; Li, Yanrong; Schmidt, Heidemarie

2016-12-07

Low power consumption is crucial for the application of resistive random access memory. In this work, we present the bipolar resistive switching in an Ag/TiO x F y /Ti/Pt stack with extremely low switch-on voltage of 0.07 V. Operating current as low as 10 nA was also obtained by conductive atomic force microscopy. The highly defective TiO x F y layer was fabricated by plasma treatment using helium, oxygen, and carbon tetrafluoride orderly. During the electroforming process, AgF nanoparticles were formed due to the diffusion of Ag + which reacted with the adsorbed F - in the TiO x F y layer. These nanoparticles are of great importance to resistive switching performance because they are believed to be conductive phases and become part of the conducting path when the sample is switched to a low-resistance state.

An oxygen-insensitive degradable resist for fabricating metallic patterns on highly curved surfaces by UV-nanoimprint lithography.

PubMed

Hu, Xin; Huang, Shisong; Gu, Ronghua; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

2014-10-01

In this paper, an oxygen-insensitive degradable resist for UV-nanoimprint is designed, com-prising a polycyclic degradable acrylate monomer, 2,10-diacryloyloxymethyl-1,4,9,12-tetraoxa-spiro [4.2.4.2] tetradecane (DAMTT), and a multifunctional thiol monomer pentaerythritol tetra(3-mercaptopropionate) (PETMP). The resist can be quickly UV-cured in the air atmosphere and achieve a high monomer conversion of over 98%, which greatly reduce the adhesion force between the resist and the soft mold. High conversion, in company with an adequate Young's modulus (about 1 GPa) and an extremely low shrinkage (1.34%), promises high nanoimprint resolution of sub-50 nm. The cross-linked resist is able to break into linear molecules in a hot acid solvent. As a result, metallic patterns are fabricated on highly curved surfaces via the lift off process without the assistance of a thermoplastic polymer layer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Production of low-affinity penicillin-binding protein by low- and high-resistance groups of methicillin-resistant Staphylococcus aureus.

PubMed Central

Murakami, K; Nomura, K; Doi, M; Yoshida, T

1987-01-01

Methicillin- and cephem-resistant Staphylococcus aureus (137 strains) for which the cefazolin MICs are at least 25 micrograms/ml could be classified into low-resistance (83% of strains) and high-resistance (the remaining 17%) groups by the MIC of flomoxef (6315-S), a 1-oxacephalosporin. The MICs were less than 6.3 micrograms/ml and more than 12.5 micrograms/ml in the low- and high-resistance groups, respectively. All strains produced penicillin-binding protein 2' (PBP 2'), which has been associated with methicillin resistance and which has very low affinity for beta-lactam antibiotics. Production of PBP 2' was regulated differently in low- and high-resistance strains. With penicillinase-producing strains of the low-resistance group, cefazolin, cefamandole, and cefmetazole induced PBP 2' production about 5-fold, while flomoxef induced production 2.4-fold or less. In contrast, penicillinase-negative variants of low-resistance strains produced PBP 2' constitutively in large amounts and induction did not occur. With high-resistance strains, flomoxef induced PBP 2' to an extent similar to that of cefazolin in both penicillinase-producing and -negative strains, except for one strain in which the induction did not occur. The amount of PBP 2' induced by beta-lactam antibiotics in penicillinase-producing strains of the low-resistance group correlated well with resistance to each antibiotic. Large amounts of PBP 2' in penicillinase-negative variants of the low-resistance group did not raise the MICs of beta-lactam compounds, although these strains were more resistant when challenged with flomoxef for 2 h. Different regulation of PBP 2' production was demonstrated in the high- and low-resistance groups, and factor(s) other than PBP 2' were suggested to be involved in the methicillin resistance of high-resistance strains. Images PMID:3499861

Low electrical resistivity carbon nanotube and polyethylene nanocomposites for aerospace and energy exploration applications

NASA Astrophysics Data System (ADS)

Moloney, Padraig G.

An investigation was conducted towards the development and optimization of low electrical resistivity carbon nanotube (CNT) and thermoplastic composites as potential materials for future wire and cable applications in aerospace and energy exploration. Fundamental properties of the polymer, medium density polyethylene (MDPE), such as crystallinity were studied and improved for composite use. A parallel effort was undertaken on a broad selection of CNT, including single wall, double wall and multi wall carbon nanotubes, and included research of material aspects relevant to composite application and low resistivity such as purity, diameter and chirality. With an emphasis on scalability, manufacturing and purification methods were developed, and a solvent-based composite fabrication method was optimized. CNT MDPE composites were characterized via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman spectroscopy, and multiple routes of electron microscopy. Techniques including annealing and pressure treatments were used to further improve the composites' resulting electrical performance. Enhancement of conductivity was explored via exposure to a focused microwave beam. A novel doping method was developed using antimony pentafluoride (SbF5) to reduce the resistivity of the bulk CNT. Flexible composites, malleable under heat and pressure, were produced with exceptional electrical resistivities reaching as low as 2*10-6O·m (5*105S/m). A unique gas sensor application utilizing the unique electrical resistivities of the produced CNT-MDPE composites was developed. The materials proved suitable as a low weight and low energy sensing material for dimethyl methylphosphonate (DMMP), a nerve gas simulant.

Development of fire-resistant, low smoke generating, thermally stable end items for aircraft and spacecraft

NASA Technical Reports Server (NTRS)

Gagliani, J.; Sorathia, U. A. K.; Wilcoxson, A. L.

1977-01-01

Materials were developed to improve aircraft interior materials by modifying existing polymer structures, refining the process parameters, and by the use of mechanical configurations designed to overcome specific deficiencies. The optimization, selection, and fabrication of five fire resistant, low smoke emitting open cell foams are described for five different types of aircraft cabin structures. These include: resilient foams, laminate floor and wall paneling, thermal/acoustical insulation, molded shapes, and coated fabrics. All five have been produced from essentially the same polyimide precursor and have resulted in significant benefits from transfer of technology between the various tasks.

Flame-resistant textiles

NASA Technical Reports Server (NTRS)

Fogg, L. C.; Stringham, R. S.; Toy, M. S.

1980-01-01

Flame resistance treatment for acid resistant polyamide fibers involving photoaddition of fluorocarbons to surface has been scaled up to treat 10 yards of commercial width (41 in.) fabric. Process may be applicable to other low cost polyamides, polyesters, and textiles.

Luminous fabric devices for wearable low-level light therapy

PubMed Central

Shen, Jing; Chui, Chunghin; Tao, Xiaoming

2013-01-01

In this paper, a flexible luminous fabric device was developed and investigated for wearable three-dimensionally fitted low-level light therapy. The fabric device exhibited excellent optical and thermal properties. Its optical power density and operating temperature were stable during usage for 10 hours. In vitro experiments demonstrated a significant increase in collagen production in human fibroblast irradiated by the fabric device, compared with the fibroblast without light irradiation. A series of tests were conducted for the safety of the fabric for human skin contact according to ISO standard ISO 10993-1:2003. The results showed that there was no potential hazard when the luminous fabrics were in direct contact with human skin. PMID:24409391

Combined fabrication process for high-precision aspheric surface based on smoothing polishing and magnetorheological finishing

NASA Astrophysics Data System (ADS)

Nie, Xuqing; Li, Shengyi; Song, Ci; Hu, Hao

2014-08-01

Due to the different curvature everywhere, the aspheric surface is hard to achieve high-precision accuracy by the traditional polishing process. Controlling of the mid-spatial frequency errors (MSFR), in particular, is almost unapproachable. In this paper, the combined fabrication process based on the smoothing polishing (SP) and magnetorheological finishing (MRF) is proposed. The pressure distribution of the rigid polishing lap and semi-flexible polishing lap is calculated. The shape preserving capacity and smoothing effect are compared. The feasibility of smoothing aspheric surface with the semi-flexible polishing lap is verified, and the key technologies in the SP process are discussed. Then, A K4 parabolic surface with the diameter of 500mm is fabricated based on the combined fabrication process. A Φ150 mm semi-flexible lap is used in the SP process to control the MSFR, and the deterministic MRF process is applied to figure the surface error. The root mean square (RMS) error of the aspheric surface converges from 0.083λ (λ=632.8 nm) to 0.008λ. The power spectral density (PSD) result shows that the MSFR are well restrained while the surface error has a great convergence.

High sensitivity knitted fabric strain sensors

NASA Astrophysics Data System (ADS)

Xie, Juan; Long, Hairu; Miao, Menghe

2016-10-01

Wearable sensors are increasingly used in smart garments for detecting and transferring vital signals and body posture, movement and respiration. Existing fabric strain sensors made from metallized yarns have low sensitivity, poor comfort and low durability to washing. Here we report a knitted fabric strain sensor made from a cotton/stainless steel (SS) fibre blended yarn which shows much higher sensitivity than sensors knitted from metallized yarns. The fabric feels softer than pure cotton textiles owing to the ultrafine stainless steel fibres and does not lose its electrical property after washing. The reason for the high sensitivity of the cotton/SS knitted fabric sensor was explored by comparing its sensing mechanism with the knitted fabric sensor made from metallized yarns. The results show that the cotton/SS yarn-to-yarn contact resistance is highly sensitive to strain applied to hooked yarn loops.

Study of skin model and geometry effects on thermal performance of thermal protective fabrics

NASA Astrophysics Data System (ADS)

Zhu, Fanglong; Ma, Suqin; Zhang, Weiyuan

2008-05-01

Thermal protective clothing has steadily improved over the years as new materials and improved designs have reached the market. A significant method that has brought these improvements to the fire service is the NFPA 1971 standard on structural fire fighters’ protective clothing. However, this testing often neglects the effects of cylindrical geometry on heat transmission in flame resistant fabrics. This paper deals with methods to develop cylindrical geometry testing apparatus incorporating novel skin bioheat transfer model to test flame resistant fabrics used in firefighting. Results show that fabrics which shrink during the test can have reduced thermal protective performance compared with the qualities measured with a planar geometry tester. Results of temperature differences between skin simulant sensors of planar and cylindrical tester are also compared. This test method provides a new technique to accurately and precisely characterize the thermal performance of thermal protective fabrics.

Fabrication methods for low impedance lithium polymer electrodes

DOEpatents

Chern, T.S.; MacFadden, K.O.; Johnson, S.L.

1997-12-16

A process is described for fabricating an electrolyte-electrode composite suitable for high energy alkali metal battery that includes mixing composite electrode materials with excess liquid, such as ethylene carbonate or propylene carbonate, to produce an initial formulation, and forming a shaped electrode therefrom. The excess liquid is then removed from the electrode to compact the electrode composite which can be further compacted by compression. The resulting electrode exhibits at least a 75% lower resistance.

Fabrication methods for low impedance lithium polymer electrodes

DOEpatents

Chern, Terry Song-Hsing; MacFadden, Kenneth Orville; Johnson, Steven Lloyd

1997-01-01

A process for fabricating an electrolyte-electrode composite suitable for high energy alkali metal battery that includes mixing composite electrode materials with excess liquid, such as ethylene carbonate or propylene carbonate, to produce an initial formulation, and forming a shaped electrode therefrom. The excess liquid is then removed from the electrode to compact the electrode composite which can be further compacted by compression. The resulting electrode exhibits at least a 75% lower resistance.

Precise fabrication of a 5 nm graphene nanopore with a helium ion microscope for biomolecule detection

NASA Astrophysics Data System (ADS)

Deng, Yunsheng; Huang, Qimeng; Zhao, Yue; Zhou, Daming; Ying, Cuifeng; Wang, Deqiang

2017-01-01

We report a scalable method to fabricate high-quality graphene nanopores for biomolecule detection using a helium ion microscope (HIM). HIM milling shows promising capabilities for precisely controlling the size and shape, and may allow for the potential production of nanopores at wafer scale. Nanopores could be fabricated at different sizes ranging from 5 to 30 nm in diameter in few minutes. Compared with the current solid-state nanopore fabrication techniques, e.g. transmission electron microscopy, HIM is fast. Furthermore, we investigated the exposure-time dependence of graphene nanopore formation: the rate of pore expansion did not follow a simple linear relationship with exposure time, but a fast expansion rate at short exposure time and a slow rate at long exposure time. In addition, we performed biomolecule detection with our patterned graphene nanopore. The ionic current signals induced by 20-base single-stranded DNA homopolymers could be used as a basis for homopolymer differentiation. However, the charge interaction of homopolymer chains with graphene nanopores, and the conformations of homopolymer chains need to be further considered to improve the accuracy of discrimination.

A strategy for design and fabrication of low cost microchannel for future reproductivity of bio/chemical lab-on-chip application

NASA Astrophysics Data System (ADS)

Humayun, Q.; Hashim, U.; Ruzaidi, C. M.; Noriman, N. Z.

2017-03-01

The fabrication and characterization of sensitive and selective fluids delivery system for the application of nano laboratory on a single chip is a challenging task till to date. This paper is one of the initial attempt to resolve this challenging task by using a simple, cost effective and reproductive technique for pattering a microchannel structures on SU-8 resist. The objective of the research is to design, fabricate and characterize polydimethylsiloxane (PDMS) microchannel. The proposed device mask was designed initially by using AutoCAD software and then the designed was transferred to transparency sheet and to commercial chrome mask for better photo masking process. The standard photolithography process coupled with wet chemical etching process was used for the fabrication of proposed microchannel. This is a low cost fabrication technique for the formation of microchannel structure at resist. The fabrication process start from microchannel formation and then the structure was transformed to PDMS substrate, the microchannel structure was cured from mold and then the cured mold was bonded with the glass substrate by plasma oxidation bonding process. The surface morphology was characterized by high power microscope (HPM) and the structure was characterized by Hawk 3 D surface nanoprofiler. The next part of the research will be focus onto device testing and validation by using real biological samples by the implementation of a simple manual injection technique.

Brazed Diamond Micropowder Bur Fabricated by Supersonic Frequency Induction Heating for Precision Machining

NASA Astrophysics Data System (ADS)

Ma, Bojiang; Lou, Jianpeng; Pang, Qian

2014-04-01

The common brazed diamond micropowder bur fabricated in a vacuum furnace produces an even brazing alloy surface. The small brazed diamond grits show low outcropping from the brazing alloy surface, and the chip space between them is small. The bur shows a low grinding efficiency and poor heat dissipation. In this study, a brazed diamond micropowder bur was fabricated by supersonic frequency induction heating. The method afforded a fluctuant surface on the brazing alloy. The brazed diamond grits with an outcropping height distributed uniformly on the fluctuant surface. The fluctuant surface showed a certain chip space. These characteristics of the tool increased the grinding efficiency and decreased the temperature of the grinding arc area. The roughness R a of the ceramic tile surface trimmed by the tool cylinder was between 0.09 and 0.12 μm. In the first 90 min, the decrease in the weight of the ceramic tile ground by the tool cylinder was higher than that ground by the tool fabricated in a vacuum furnace. When the ceramic tile was cylindrically ground, the temperature of the grinding arc area measured using a thermocouple remained below 70 °C.

Low Cost Precision Lander for Lunar Exploration

NASA Astrophysics Data System (ADS)

Hoppa, G. V.; Head, J. N.; Gardner, T. G.; Seybold, K. G.

2004-12-01

For 60 years the US Defense Department has invested heavily in producing small, low mass, precision-guided vehicles. The technologies matured under these programs include terrain-aided navigation, closed loop terminal guidance algorithms, robust autopilots, high thrust-to-weight propulsion, autonomous mission management software, sensors, and data fusion. These technologies will aid NASA in addressing New Millennium Science and Technology goals as well as the requirements flowing from the Moon to Mars vision articulated in January 2004. Establishing and resupplying a long-term lunar presence will require automated landing precision not yet demonstrated. Precision landing will increase safety and assure mission success. In our lander design, science instruments amount to 10 kg, 16% of the lander vehicle mass. This compares favorably with 7% for Mars Pathfinder and less than 15% for Surveyor. The mission design relies on a cruise stage for navigation and TCMs for the lander's flight to the moon. The landing sequence begins with a solid motor burn to reduce the vehicle speed to 300-450 m/s. At this point the lander is about 2 minutes from touchdown and has 600 to 700 m/s delta-v capability. This allows for about 10 km of vehicle divert during terminal descent. This concept of operations closely mimics missile operational protocol used for decades: the vehicle remains inert, then must execute its mission flawlessly on a moment's notice. The vehicle design uses a propulsion system derived from heritage MDA programs. A redesigned truss provides hard points for landing gear, electronics, power supply, and science instruments. A radar altimeter and a Digital Scene Matching Area Correlator (DSMAC) provide data for the terminal guidance algorithms. This approach leverages the billions of dollars DoD has invested in these technologies, to land useful science payloads precisely on the lunar surface at relatively low cost.

Effect of liquid immersion of PEDOT: PSS-coated polyester fabric on surface resistance and wettability

NASA Astrophysics Data System (ADS)

Getnet Tadesse, Melkie; Loghin, Carmen; Chen, Yan; Wang, Lichuan; Catalin, Dumitras; Nierstrasz, Vincent

2017-06-01

Coating of textile fabrics with poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) is one of the methods used for obtaining functional or smart applications. In this work, we prepared PEDOT:PSS polymer with certain additives such as polyethylene glycol, methanol (MeOH), and ethylene glycol on polyester fabric substrates by a simple immersion process. Surface resistance was measured and analyzed with analysis of variance to determine the coating parameters at 95% confidence level. Fourier transform infrared (FTIR) analysis and scanning electron microscopy (SEM) study of the samples were performed. Contact angle and washing fastness measurements were conducted, to observe the wettability and washing fastness of the samples, respectively. Surface resistance values were decreased by a factor of 100, due to conductive enhancers. As the immersion time and temperature condition varies, surface resistance showed no difference, statistically. FTIR analysis supports the idea that the mechanism responsible for the conductivity enhancement is the partial replacement of PSS from PEDOT chain by forming a hydrogen bond with hydroxyl ion (OH) of the conductive enhancers. A SEM images showed that PEDOT:PSS is well distributed to the surface of the fabrics. Contact angle measurements showed morphology change in the samples. The conductivity was reasonably stable after 10 washing cycles. Altogether, an effective simple immersion of coated polyester fabric is presented to achieve functional textiles that offer a broad range of possible applications.

Precision shape modification of nanodevices with a low-energy electron beam

DOEpatents

Zettl, Alex; Yuzvinsky, Thomas David; Fennimore, Adam

2010-03-09

Methods of shape modifying a nanodevice by contacting it with a low-energy focused electron beam are disclosed here. In one embodiment, a nanodevice may be permanently reformed to a different geometry through an application of a deforming force and a low-energy focused electron beam. With the addition of an assist gas, material may be removed from the nanodevice through application of the low-energy focused electron beam. The independent methods of shape modification and material removal may be used either individually or simultaneously. Precision cuts with accuracies as high as 10 nm may be achieved through the use of precision low-energy Scanning Electron Microscope scan beams. These methods may be used in an automated system to produce nanodevices of very precise dimensions. These methods may be used to produce nanodevices of carbon-based, silicon-based, or other compositions by varying the assist gas.

Precision forging technology for aluminum alloy

NASA Astrophysics Data System (ADS)

Deng, Lei; Wang, Xinyun; Jin, Junsong; Xia, Juchen

2018-03-01

Aluminum alloy is a preferred metal material for lightweight part manufacturing in aerospace, automobile, and weapon industries due to its good physical properties, such as low density, high specific strength, and good corrosion resistance. However, during forging processes, underfilling, folding, broken streamline, crack, coarse grain, and other macro- or microdefects are easily generated because of the deformation characteristics of aluminum alloys, including narrow forgeable temperature region, fast heat dissipation to dies, strong adhesion, high strain rate sensitivity, and large flow resistance. Thus, it is seriously restricted for the forged part to obtain precision shape and enhanced property. In this paper, progresses in precision forging technologies of aluminum alloy parts were reviewed. Several advanced precision forging technologies have been developed, including closed die forging, isothermal die forging, local loading forging, metal flow forging with relief cavity, auxiliary force or vibration loading, casting-forging hybrid forming, and stamping-forging hybrid forming. High-precision aluminum alloy parts can be realized by controlling the forging processes and parameters or combining precision forging technologies with other forming technologies. The development of these technologies is beneficial to promote the application of aluminum alloys in manufacturing of lightweight parts.

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.

Robust Polypropylene Fabrics Super-Repelling Various Liquids: A Simple, Rapid and Scalable Fabrication Method by Solvent Swelling.

PubMed

Zhu, Tang; Cai, Chao; Duan, Chunting; Zhai, Shuai; Liang, Songmiao; Jin, Yan; Zhao, Ning; Xu, Jian

2015-07-01

A simple, rapid (10 s) and scalable method to fabricate superhydrophobic polypropylene (PP) fabrics is developed by swelling the fabrics in cyclohexane/heptane mixture at 80 °C. The recrystallization of the swollen macromolecules on the fiber surface contributes to the formation of submicron protuberances, which increase the surface roughness dramatically and result in superhydrophobic behavior. The superhydrophobic PP fabrics possess excellent repellency to blood, urine, milk, coffee, and other common liquids, and show good durability and robustness, such as remarkable resistances to water penetration, abrasion, acidic/alkaline solution, and boiling water. The excellent comprehensive performance of the superhydrophobic PP fabrics indicates their potential applications as oil/water separation materials, protective garments, diaper pads, or other medical and health supplies. This simple, fast and low cost method operating at a relatively low temperature is superior to other reported techniques for fabricating superhydrophobic PP materials as far as large scale manufacturing is considered. Moreover, the proposed method is applicable for preparing superhydrophobic PP films and sheets as well.

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.

Low resistivity W{sub x}V{sub 1−x}O{sub 2}-based multilayer structure with high temperature coefficient of resistance for microbolometer applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Émond, Nicolas; Hendaoui, Ali; Chaker, Mohamed, E-mail: chaker@emt.inrs.ca

2015-10-05

Materials that exhibit semiconductor-to-metal phase transition (SMT) are commonly used as sensing layers for the fabrication of uncooled microbolometers. The development of highly responsive microbolometers would benefit from using a sensing material that possesses a large thermal coefficient of resistance (TCR) close to room temperature and a resistivity low enough to compromise between noise reduction and high TCR, while it should also satisfies the requirements of current CMOS technology. Moreover, a TCR that remains constant when the IR camera surrounding temperature varies would contribute to achieve reliable temperature measurements without additional corrections steps for TCR temperature dependence. In this paper,more » the characteristics of the SMT occurring in undoped and tungsten-doped vanadium dioxide thin films deposited on LaAlO{sub 3} (100) substrates are investigated. They are further exploited to fabricate a W{sub x}V{sub 1−x}O{sub 2} (0 ≤ x ≤ 2.5) multilayer structure exhibiting a bottom-up gradient of tungsten content. This MLS displays a combination of properties that is promising for application to uncooled microbolometer, such as a large TCR of −10.4%/ °C and low resistivity values ranging from 0.012 to 0.10 Ω-cm over the temperature range 22 °C–42 °C.« less

Effect of Atomic Hydrogen on Preparation of Highly Moisture-Resistive SiNx Films at Low Substrate Temperatures

NASA Astrophysics Data System (ADS)

Heya, Akira; Niki, Toshikazu; Takano, Masahiro; Yonezawa, Yasuto; Minamikawa, Toshiharu; Muroi, Susumu; Minami, Shigehira; Izumi, Akira; Masuda, Atsushi; Umemoto, Hironobu; Matsumura, Hideki

2004-12-01

Highly moisture-resistive SiNx films on a Si substrate are obtained at substrate temperatures of 80°C by catalytic chemical vapor deposition (Cat-CVD) using a source gas with H2. Atomic hydrogen effected the selective etching of a weak-bond regions and an increase in atomic density induced by the energy of the surface reaction. It is concluded that Cat-CVD using H2 is a promising candidate for the fabrication of highly moisture-resistive SiNx films at low temperatures.

Biomedical microfluidic devices by using low-cost fabrication techniques: A review.

PubMed

Faustino, Vera; Catarino, Susana O; Lima, Rui; Minas, Graça

2016-07-26

One of the most popular methods to fabricate biomedical microfluidic devices is by using a soft-lithography technique. However, the fabrication of the moulds to produce microfluidic devices, such as SU-8 moulds, usually requires a cleanroom environment that can be quite costly. Therefore, many efforts have been made to develop low-cost alternatives for the fabrication of microstructures, avoiding the use of cleanroom facilities. Recently, low-cost techniques without cleanroom facilities that feature aspect ratios more than 20, for fabricating those SU-8 moulds have been gaining popularity among biomedical research community. In those techniques, Ultraviolet (UV) exposure equipment, commonly used in the Printed Circuit Board (PCB) industry, replaces the more expensive and less available Mask Aligner that has been used in the last 15 years for SU-8 patterning. Alternatively, non-lithographic low-cost techniques, due to their ability for large-scale production, have increased the interest of the industrial and research community to develop simple, rapid and low-cost microfluidic structures. These alternative techniques include Print and Peel methods (PAP), laserjet, solid ink, cutting plotters or micromilling, that use equipment available in almost all laboratories and offices. An example is the xurography technique that uses a cutting plotter machine and adhesive vinyl films to generate the master moulds to fabricate microfluidic channels. In this review, we present a selection of the most recent lithographic and non-lithographic low-cost techniques to fabricate microfluidic structures, focused on the features and limitations of each technique. Only microfabrication methods that do not require the use of cleanrooms are considered. Additionally, potential applications of these microfluidic devices in biomedical engineering are presented with some illustrative examples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fabrication technology

NASA Astrophysics Data System (ADS)

1988-05-01

Many laboratory programs continue to need optical components of ever-increasing size and accuracy. Unfortunately, optical surfaces produced by the conventional sequence of grinding, lapping, and polishing can become prohibitively expensive. Research in the Fabrication Technology area focuses on methods of fabricating components with heretofore unrealized levels of precision. In FY87, researchers worked to determine the fundamental mechanical limits of material removal, experimented with unique material removal and deposition processes, developed servo systems for controlling the geometric position of ultraprecise machine tools, and advanced the ability to precisely measure contoured workpieces. Continued work in these areas will lead to more cost-effective processes to fabricate even higher quality optical components for advanced lasers and for visible, ultraviolet, and X-ray diagnostic systems.

Synthesizing A Phase Changing Bistable Electroactive Polymer And Silver Nanoparticles Coated Fabric As A Resistive Heating Element

NASA Astrophysics Data System (ADS)

Ren, Zhi

Transducer technologies that convert energy from one form to another (e.g. electrical energy to mechanical energy or thermal energy and vise versa) are considered as the basic building blocks of robots and wearable electronics, two of the rapidly emerging technologies that impact our daily life. With an emphasis on developing the essential smart materials, this dissertation focuses on two specific transducer technologies, bistable large-strain electro-mechanical actuation and resistive Joule heating, in pursuit of refreshable Braille electronic displays and wearable thermal management element, respectively. Dielectric elastomers (DEs) have been intensively studied for their promising ability to mimic human muscles in providing efficient electro-mechanical actuation. They exhibit a unique combination of properties, including large strain, fast response, high energy density, mechanical compliancy, lightweight, and low cost. However, the softness of the DE materials, which is a prerequisite for electrically induced large actuation strain, has been hindering their application in adaptive structures. In these applications such as braille displays, a certain amount of mechanical support is necessary in addition to large strains for the device or system to function. Bistable electroactive polymers (BSEP) that leverage the electrically induced large-strain actuation of DE actuators and the bi-stable rigid-to-rigid deformation of shape memory polymers are innovated to provide large electrical actuation strain in their rubbery state and fix the deformation by cooling down to room temperature to incorporate mechanical rigidity. BSEP materials that can suppress electromechanical instability and exhibit stable mechanical properties in the rubbery state are desired. A bimodal BSEP material with a glass transition temperature right above room temperature has been synthesized employing simple UV curing process. The BSEP has a large storage modulus over 1GPa at room temperature

Low-power grating detection system chip for high-speed low-cost length and angle precision measurement

NASA Astrophysics Data System (ADS)

Hou, Ligang; Luo, Rengui; Wu, Wuchen

2006-11-01

This paper forwards a low power grating detection chip (EYAS) on length and angle precision measurement. Traditional grating detection method, such as resister chain divide or phase locked divide circuit are difficult to design and tune. The need of an additional CPU for control and display makes these methods' implementation more complex and costly. Traditional methods also suffer low sampling speed for the complex divide circuit scheme and CPU software compensation. EYAS is an application specific integrated circuit (ASIC). It integrates micro controller unit (MCU), power management unit (PMU), LCD controller, Keyboard interface, grating detection unit and other peripherals. Working at 10MHz, EYAS can afford 5MHz internal sampling rate and can handle 1.25MHz orthogonal signal from grating sensor. With a simple control interface by keyboard, sensor parameter, data processing and system working mode can be configured. Two LCD controllers can adapt to dot array LCD or segment bit LCD, which comprised output interface. PMU alters system between working and standby mode by clock gating technique to save power. EYAS in test mode (system action are more frequently than real world use) consumes 0.9mw, while 0.2mw in real world use. EYAS achieved the whole grating detection system function, high-speed orthogonal signal handling in a single chip with very low power consumption.

Precision Extruding Deposition for Freeform Fabrication of PCL and PCL-HA Tissue Scaffolds

NASA Astrophysics Data System (ADS)

Shor, L.; Yildirim, E. D.; Güçeri, S.; Sun, W.

Computer-aided tissue engineering approach was used to develop a novel Precision Extrusion Deposition (PED) process to directly fabricate Polycaprolactone (PCL) and composite PCL/Hydroxyapatite (PCL-HA) tissue scaffolds. The process optimization was carried out to fabricate both PCL and PCL-HA (25% concentration by weight of HA) with a controlled pore size and internal pore structure of the 0°/90° pattern. Two groups of scaffolds having 60 and 70% porosity and with pore sizes of 450 and 750 microns, respectively, were evaluated for their morphology and compressive properties using Scanning Electron Microscopy (SEM) and mechanical testing. The surface modification with plasma was conducted on PCL scaffold to increase the cellular attachment and proliferation. Our results suggested that inclusion of HA significantly increased the compressive modulus from 59 to 84 MPa for 60% porous scaffolds and from 30 to 76 MPa for 70% porous scaffolds. In vitro cell-scaffolds interaction study was carried out using primary fetal bovine osteoblasts to assess the feasibility of scaffolds for bone tissue engineering application. In addition, the results in surface hydrophilicity and roughness show that plasma surface modification can increase the hydrophilicity while introducing the nano-scale surface roughness on PCL surface. The cell proliferation and differentiation were calculated by Alamar Blue assay and by determining alkaline phosphatase activity. The osteoblasts were able to migrate and proliferate over the cultured time for both PCL as well as PCL-HA scaffolds. Our study demonstrated the viability of the PED process to the fabricate PCL and PCL-HA composite scaffolds having necessary mechanical property, structural integrity, controlled pore size and pore interconnectivity desired for bone tissue engineering.

Analysis of the Murine Immune Response to Pulmonary Delivery of Precisely Fabricated Nano- and Microscale Particles

PubMed Central

Roberts, Reid A.; Shen, Tammy; Allen, Irving C.; Hasan, Warefta; DeSimone, Joseph M.; Ting, Jenny P. Y.

2013-01-01

Nanomedicine has the potential to transform clinical care in the 21st century. However, a precise understanding of how nanomaterial design parameters such as size, shape and composition affect the mammalian immune system is a prerequisite for the realization of nanomedicine's translational promise. Herein, we make use of the recently developed Particle Replication in Non-wetting Template (PRINT) fabrication process to precisely fabricate particles across and the nano- and micro-scale with defined shapes and compositions to address the role of particle design parameters on the murine innate immune response in both in vitro and in vivo settings. We find that particles composed of either the biodegradable polymer poly(lactic-co-glycolic acid) (PLGA) or the biocompatible polymer polyethylene glycol (PEG) do not cause release of pro-inflammatory cytokines nor inflammasome activation in bone marrow-derived macrophages. When instilled into the lungs of mice, particle composition and size can augment the number and type of innate immune cells recruited to the lungs without triggering inflammatory responses as assayed by cytokine release and histopathology. Smaller particles (80×320 nm) are more readily taken up in vivo by monocytes and macrophages than larger particles (6 µm diameter), yet particles of all tested sizes remained in the lungs for up to 7 days without clearance or triggering of host immunity. These results suggest rational design of nanoparticle physical parameters can be used for sustained and localized delivery of therapeutics to the lungs. PMID:23593509

Fabrication of a Cryogenic Terahertz Emitter for Bolometer Focal Plane Calibrations

NASA Technical Reports Server (NTRS)

Chervenak, James; Brown, Ari; Wollack, Edward

2012-01-01

A fabrication process is reported for prototype emitters of THz radiation, which operate cryogenically, and should provide a fast, stable blackbody source suitable for characterization of THz devices. The fabrication has been demonstrated and, at the time of this reporting, testing was underway. The emitter is similar to a monolithic silicon bolometer in design, using both a low-noise thermometer and a heater element on a thermally isolated stage. An impedance-matched, high-emissivity coat ing is also integrated to tune the blackbody properties. This emitter is designed to emit a precise amount of power as a blackbody spectrum centered on terahertz frequencies. The emission is a function of the blackbody temperature. An integrated resistive heater and thermometer system can control the temperature of the blackbody with greater precision than previous incarnations of calibration sources that relied on blackbody emission. The emitter is fabricated using a silicon- on-insulator substrate wafer. The buried oxide is chosen to be less than 1 micron thick, and the silicon device thickness is 1-2 microns. Layers of phosphorus compensated with boron are implanted into and diffused throughout the full thickness of the silicon device layer to create the thermometer and heater components. Degenerately doped wiring is implanted to connect the devices to wire-bondable contact pads at the edge of the emitter chip. Then the device is micromachined to remove the thick-handle silicon behind the thermometer and heater components, and to thermally isolate it on a silicon membrane. An impedance- matched emissive coating (ion assisted evaporated Bi) is applied to the back of the membrane to enable high-efficiency emission of the blackbody spectrum.

Contact Resistance and Channel Conductance of Graphene Field-Effect Transistors under Low-Energy Electron Irradiation

PubMed Central

Giubileo, Filippo; Di Bartolomeo, Antonio; Martucciello, Nadia; Romeo, Francesco; Iemmo, Laura; Romano, Paola; Passacantando, Maurizio

2016-01-01

We studied the effects of low-energy electron beam irradiation up to 10 keV on graphene-based field effect transistors. We fabricated metallic bilayer electrodes to contact mono- and bi-layer graphene flakes on SiO2, obtaining specific contact resistivity ρc≈19 kΩ·µm2 and carrier mobility as high as 4000 cm2·V−1·s−1. By using a highly doped p-Si/SiO2 substrate as the back gate, we analyzed the transport properties of the device and the dependence on the pressure and on the electron bombardment. We demonstrate herein that low energy irradiation is detrimental to the transistor current capability, resulting in an increase in contact resistance and a reduction in carrier mobility, even at electron doses as low as 30 e−/nm2. We also show that irradiated devices recover their pristine state after few repeated electrical measurements. PMID:28335335

Variability metrics in Josephson Junction fabrication for Quantum Computing circuits

NASA Astrophysics Data System (ADS)

Rosenblatt, Sami; Hertzberg, Jared; Brink, Markus; Chow, Jerry; Gambetta, Jay; Leng, Zhaoqi; Houck, Andrew; Nelson, J. J.; Plourde, Britton; Wu, Xian; Lake, Russell; Shainline, Jeff; Pappas, David; Patel, Umeshkumar; McDermott, Robert

Multi-qubit gates depend on the relative frequencies of the qubits. To reliably build multi-qubit devices therefore requires careful fabrication of Josephson junctions in order to precisely set their critical currents. The Ambegaokar-Baratoff relation between tunnel conductance and critical current implies a correlation between qubit frequency spread and tunnel junction resistance spread. Here we discuss measurement of large numbers of tunnel junctions to assess these resistance spreads, which can exceed 5% of mean resistance. With the goal of minimizing these spreads, we investigate process parameters such as lithographic junction area, evaporation and masking scheme, oxidation conditions, and substrate choice, as well as test environment, design and setup. In addition, trends of junction resistance with temperature are compared with theoretical models for further insights into process and test variability.

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.

A facile and low-cost micro fabrication material: flash foam.

PubMed

He, Yong; Xiao, Xiao; Wu, Yan; Fu, Jian-zhong

2015-08-28

Although many microfabrication methods have been reported, the preliminary replication templates used in most microfabrication still depend on the expensive and long-period photolithography. This paper explores an alternative replication templates based on a daily used material, flash foam (FF), and proposes a facile microfabrication method, flash foam stamp lithography (FFSL). When FF is exposed with a desired pattern mask, the negative of the pattern is transferred to its surface and micro structures are formed due to the shrinkage of the exposed area. As FF is commonly used in personal stamps, FFSL is very simple and cost-effective. In this paper, we demonstrated that FF is a good and low-cost template for many micro fabrication methods, such as micro casting and soft lithography. Thus, designing and fabricating micro structures at personal office immediately become possible with FFSL. Furthermore, we demonstrated that multi-scale micro structures can be easily fabricated by double exposure with FFSL. Skin textures is used as another case to demonstrate that FFSL can fabricate structures with different depth in a single exposure. As a result, FF shows a promising future in biology, and analytical chemistry, such as rapid fabrication of point of care diagnostics and microfluidic analytical devices with low cost.

A facile and low-cost micro fabrication material: flash foam

PubMed Central

He, Yong; Xiao, Xiao; Wu, Yan; Fu, Jian-zhong

2015-01-01

Although many microfabrication methods have been reported, the preliminary replication templates used in most microfabrication still depend on the expensive and long-period photolithography. This paper explores an alternative replication templates based on a daily used material, flash foam (FF), and proposes a facile microfabrication method, flash foam stamp lithography (FFSL). When FF is exposed with a desired pattern mask, the negative of the pattern is transferred to its surface and micro structures are formed due to the shrinkage of the exposed area. As FF is commonly used in personal stamps, FFSL is very simple and cost-effective. In this paper, we demonstrated that FF is a good and low-cost template for many micro fabrication methods, such as micro casting and soft lithography. Thus, designing and fabricating micro structures at personal office immediately become possible with FFSL. Furthermore, we demonstrated that multi-scale micro structures can be easily fabricated by double exposure with FFSL. Skin textures is used as another case to demonstrate that FFSL can fabricate structures with different depth in a single exposure. As a result, FF shows a promising future in biology, and analytical chemistry, such as rapid fabrication of point of care diagnostics and microfluidic analytical devices with low cost. PMID:26314247

Extremely Low Operating Current Resistive Memory Based on Exfoliated 2D Perovskite Single Crystals for Neuromorphic Computing.

PubMed

Tian, He; Zhao, Lianfeng; Wang, Xuefeng; Yeh, Yao-Wen; Yao, Nan; Rand, Barry P; Ren, Tian-Ling

2017-12-26

Extremely low energy consumption neuromorphic computing is required to achieve massively parallel information processing on par with the human brain. To achieve this goal, resistive memories based on materials with ionic transport and extremely low operating current are required. Extremely low operating current allows for low power operation by minimizing the program, erase, and read currents. However, materials currently used in resistive memories, such as defective HfO x , AlO x , TaO x , etc., cannot suppress electronic transport (i.e., leakage current) while allowing good ionic transport. Here, we show that 2D Ruddlesden-Popper phase hybrid lead bromide perovskite single crystals are promising materials for low operating current nanodevice applications because of their mixed electronic and ionic transport and ease of fabrication. Ionic transport in the exfoliated 2D perovskite layer is evident via the migration of bromide ions. Filaments with a diameter of approximately 20 nm are visualized, and resistive memories with extremely low program current down to 10 pA are achieved, a value at least 1 order of magnitude lower than conventional materials. The ionic migration and diffusion as an artificial synapse is realized in the 2D layered perovskites at the pA level, which can enable extremely low energy neuromorphic computing.

Studies on fast triggering and high precision tracking with Resistive Plate Chambers

NASA Astrophysics Data System (ADS)

Aielli, G.; Ball, R.; Bilki, B.; Chapman, J. W.; Cardarelli, R.; Dai, T.; Diehl, E.; Dubbert, J.; Ferretti, C.; Feng, H.; Francis, K.; Guan, L.; Han, L.; Hou, S.; Levin, D.; Li, B.; Liu, L.; Paolozzi, L.; Repond, J.; Roloff, J.; Santonico, R.; Song, H. Y.; Wang, X. L.; Wu, Y.; Xia, L.; Xu, L.; Zhao, T.; Zhao, Z.; Zhou, B.; Zhu, J.

2013-06-01

We report on studies of fast triggering and high precision tracking using Resistive Plate Chambers (RPCs). Two beam tests were carried out with the 180 GeV/c muon beam at CERN using glass RPCs with gas gaps of 1.15 mm and equipped with readout strips with 1.27 mm pitch. This is the first beam test of RPCs with fine-pitch readout strips that explores precision tracking and triggering capabilities. RPC signals were acquired with precision timing and charge integrating readout electronics at both ends of the strips. The time resolution was measured to be better than 600 ps and the average spatial resolution was found to be 220 μm using charge information and 287 μm only using signal arrival time information. The dual-ended readout allows the determination of the average and the difference of the signal arrival times. The average time was found to be independent of the incident particle position along the strip and is useful for triggering purposes. The time difference yielded a determination of the hit position with a precision of 7.5 mm along the strip. These results demonstrate the feasibility using RPCs for fast and high-resolution triggering and tracking.

Effect of decomposition and organic residues on resistivity of copper films fabricated via low-temperature sintering of complex particle mixed dispersions

NASA Astrophysics Data System (ADS)

Yong, Yingqiong; Nguyen, Mai Thanh; Tsukamoto, Hiroki; Matsubara, Masaki; Liao, Ying-Chih; Yonezawa, Tetsu

2017-03-01

Mixtures of a copper complex and copper fine particles as copper-based metal-organic decomposition (MOD) dispersions have been demonstrated to be effective for low-temperature sintering of conductive copper film. However, the copper particle size effect on decomposition process of the dispersion during heating and the effect of organic residues on the resistivity have not been studied. In this study, the decomposition process of dispersions containing mixtures of a copper complex and copper particles with various sizes was studied. The effect of organic residues on the resistivity was also studied using thermogravimetric analysis. In addition, the choice of copper salts in the copper complex was also discussed. In this work, a low-resistivity sintered copper film (7 × 10-6 Ω·m) at a temperature as low as 100 °C was achieved without using any reductive gas.

Fabrication of superhydrophobic cotton fabrics using crosslinking polymerization method

NASA Astrophysics Data System (ADS)

Jiang, Bin; Chen, Zhenxing; Sun, Yongli; Yang, Huawei; Zhang, Hongjie; Dou, Haozhen; Zhang, Luhong

2018-05-01

With the aim of removing and recycling oil and organic solvent from water, a facile and low-cost crosslinking polymerization method was first applied on surface modification of cotton fabrics for water/oil separation. Micro-nano hierarchical rough structure was constructed by triethylenetetramine (TETA) and trimesoyl chloride (TMC) that formed a polymeric layer on the surface of the fabric and anchored Al2O3 nanoparticles firmly between the fabric surface and the polymer layer. Superhydrophobic property was further obtained through self-assembly grafting of hydrophobic groups on the rough surface. The as-prepared cotton fabric exhibited superoleophilicity in atmosphere and superhydrophobicity both in atmosphere and under oil with the water contact angle of 153° and 152° respectively. Water/oil separation test showed that the as-prepared cotton fabric can handle with various oil-water mixtures with a high separation efficiency over 99%. More importantly, the separation efficiency remained above 98% over 20 cycles of reusing without losing its superhydrophobicity which demonstrated excellent reusability in oil/water separation process. Moreover, the as-prepared cotton fabric possessed good contamination resistance ability and self-cleaning property. Simulation washing process test showed the superhydrophobic cotton fabric maintained high value of water contact angle above 150° after 100 times washing, indicating great stability and durability. In summary, this work provides a brand-new way to surface modification of cotton fabric and makes it a promising candidate material for oil/water separation.

Precise low cost chain gears for heliostats

NASA Astrophysics Data System (ADS)

Liedke, Phillip; Lewandowski, Arkadiusz; Pfahl, Andreas; Hölle, Erwin

2016-05-01

This work investigates the potential of chain gears as precise and low cost driving systems for rim drive heliostats. After explaining chain gear basics the polygon effect and chain lengthening are investigated. The polygon effect could be measured by a heliostat with chain rim gear and the chain lengthening with an accordant test set up. Two gear stages are scope of this work: a rim gear and an intermediate gear. Dimensioning, pretensioning and designing for both stages are explained.

Low resistance, low-inductance power connectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coteus, Paul W.; Ferencz, Andrew; Hall, Shawn Anthony

An electrical connector includes an anode assembly for conducting an electrical supply current from a source to a destination, the anode assembly includes an anode formed into a first shape from sheet metal or other sheet-like conducting material. A cathode assembly conducts an electrical return current from the destination to the source, the cathode assembly includes a cathode formed into a second shape from sheet metal or other sheet-like conducting material. An insulator prevents electrical conduction between the anode and the cathode. The first and second shapes are such as to provide a conformity of one to the other, withmore » the insulator therebetween having a predetermined relatively thin thickness. A predetermined low-resistance path for the supply current is provided by the anode, a predetermined low-resistance path for the return current is provided by the cathode, and the proximity of the anode to the cathode along these paths provides a predetermined low self-inductance of the connector, where the proximity is afforded by the conformity of the first and second shapes.« less

Targeted nanomedicine for cancer therapeutics: Towards precision medicine overcoming drug resistance.

PubMed

Bar-Zeev, Maya; Livney, Yoav D; Assaraf, Yehuda G

2017-03-01

Intrinsic anticancer drug resistance appearing prior to chemotherapy as well as acquired resistance due to drug treatment, remain the dominant impediments towards curative cancer therapy. Hence, novel targeted strategies to overcome cancer drug resistance constitute a key aim of cancer research. In this respect, targeted nanomedicine offers innovative therapeutic strategies to overcome the various limitations of conventional chemotherapy, enabling enhanced selectivity, early and more precise cancer diagnosis, individualized treatment as well as overcoming of drug resistance, including multidrug resistance (MDR). Delivery systems based on nanoparticles (NPs) include diverse platforms enabling a plethora of rationally designed therapeutic nanomedicines. Here we review NPs designed to enhance antitumor drug uptake and selective intracellular accumulation using strategies including passive and active targeting, stimuli-responsive drug activation or target-activated release, triggered solely in the cancer cell or in specific organelles, cutting edge theranostic multifunctional NPs delivering drug combinations for synergistic therapy, while facilitating diagnostics, and personalization of therapeutic regimens. In the current paper we review the recent findings of the past four years and discuss the advantages and limitations of the various novel NPs-based drug delivery systems. Special emphasis is put on in vivo study-based evidences supporting significant therapeutic impact in chemoresistant cancers. A future perspective is proposed for further research and development of complex targeted, multi-stage responsive nanomedical drug delivery systems for personalized cancer diagnosis and efficacious therapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Degradation of Spacesuit Fabrics in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Gaier, James R.; Baldwin, Sammantha M.; Folz, Angela D.; Waters, Deborah L.; McCue, Terry R.; Jaworske, Donald A.; Clark, Gregory W.; Rogers, Kerry J.; Batman, Brittany; Bruce, John;

Fabrication of wear-resistant silicon microprobe tips for high-speed surface roughness scanning devices

NASA Astrophysics Data System (ADS)

Wasisto, Hutomo Suryo; Yu, Feng; Doering, Lutz; Völlmeke, Stefan; Brand, Uwe; Bakin, Andrey; Waag, Andreas; Peiner, Erwin

2015-05-01

Silicon microprobe tips are fabricated and integrated with piezoresistive cantilever sensors for high-speed surface roughness scanning systems. The fabrication steps of the high-aspect-ratio silicon microprobe tips were started with photolithography and wet etching of potassium hydroxide (KOH) resulting in crystal-dependent micropyramids. Subsequently, thin conformal wear-resistant layer coating of aluminum oxide (Al2O3) was demonstrated on the backside of the piezoresistive cantilever free end using atomic layer deposition (ALD) method in a binary reaction sequence with a low thermal process and precursors of trimethyl aluminum and water. The deposited Al2O3 layer had a thickness of 14 nm. The captured atomic force microscopy (AFM) image exhibits a root mean square deviation of 0.65 nm confirming the deposited Al2O3 surface quality. Furthermore, vacuum-evaporated 30-nm/200-nm-thick Au/Cr layers were patterned by lift-off and served as an etch mask for Al2O3 wet etching and in ICP cryogenic dry etching. By using SF6/O2 plasma during inductively coupled plasma (ICP) cryogenic dry etching, micropillar tips were obtained. From the preliminary friction and wear data, the developed silicon cantilever sensor has been successfully used in 100 fast measurements of 5- mm-long standard artifact surface with a speed of 15 mm/s and forces of 60-100 μN. Moreover, the results yielded by the fabricated silicon cantilever sensor are in very good agreement with those of calibrated profilometer. These tactile sensors are targeted for use in high-aspect-ratio microform metrology.

Fabrication and characterization of a micromachined swirl-shaped ionic polymer metal composite actuator with electrodes exhibiting asymmetric resistance.

PubMed

Feng, Guo-Hua; Liu, Kim-Min

2014-05-12

This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation.

Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

PubMed Central

Feng, Guo-Hua; Liu, Kim-Min

2014-01-01

This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

Fabrication and Characterization of Flexible and Miniaturized Humidity Sensors Using Screen-Printed TiO2 Nanoparticles as Sensitive Layer

PubMed Central

Dubourg, Georges; Segkos, Apostolos; Katona, Jaroslav; Radović, Marko; Savić, Slavica; Crnojević-Bengin, Vesna

2017-01-01

This paper describes the fabrication and the characterization of an original example of a miniaturized resistive-type humidity sensor, printed on flexible substrate in a large-scale manner. The fabrication process involves laser ablation for the design of interdigitated electrodes on PET (Poly-Ethylene Terephthalate) substrate and a screen-printing process for the deposition of the sensitive material, which is based on TiO2 nanoparticles. The laser ablation process was carefully optimized to obtain micro-scale and well-resolved electrodes on PET substrate. A functional paste based on cellulose was prepared in order to allow the precise screen-printing of the TiO2 nanoparticles as sensing material on the top of the electrodes. The current against voltage (I–V) characteristic of the sensor showed good linearity and potential for low-power operation. The results of a humidity-sensing investigation and mechanical testing showed that the fabricated miniaturized sensors have excellent mechanical stability, sensing characteristics, good repeatability, and relatively fast response/recovery times operating at room temperature. PMID:28800063

Corrosion resistance assessment of Co-Cr alloy frameworks fabricated by CAD/CAM milling, laser sintering, and casting methods.

PubMed

Tuna, Süleyman Hakan; Özçiçek Pekmez, Nuran; Kürkçüoğlu, Işin

2015-11-01

The effects of fabrication methods on the corrosion resistance of frameworks produced with Co-Cr alloys are not clear. The purpose of this in vitro study was to evaluate the electrochemical corrosion resistance of Co-Cr alloy specimens that were fabricated by conventional casting, milling, and laser sintering. The specimens fabricated with 3 different methods were investigated by potentiodynamic tests and electrochemical impedance spectroscopy in an artificial saliva. Ions released into the artificial saliva were estimated with inductively coupled plasma-mass spectrometry, and the results were statistically analyzed. The specimen surfaces were investigated with scanning electron microscopy before and after the tests. In terms of corrosion current and Rct properties, statistically significant differences were found both among the means of the methods and among the means of the material groups (P<.05). With regard to ions released, a statistically significant difference was found among the material groups (P<.05); however, no difference was found among the methods. Scanning electron microscopic imaging revealed that the specimens produced by conventional casting were affected to a greater extent by etching and electrochemical corrosion than those produced by milling and laser sintering. The corrosion resistance of a Co-Cr alloy specimens fabricated by milling or laser sintering was greater than that of the conventionally cast alloy specimens. The Co-Cr specimens produced by the same method also differed from one another in terms of corrosion resistance. These differences may be related to the variations in the alloy compositions. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Graphene Aerogel Templated Fabrication of Phase Change Microspheres as Thermal Buffers in Microelectronic Devices.

PubMed

Wang, Xuchun; Li, Guangyong; Hong, Guo; Guo, Qiang; Zhang, Xuetong

2017-11-29

Phase change materials, changing from solid to liquid and vice versa, are capable of storing and releasing a large amount of thermal energy during the phase change, and thus hold promise for numerous applications including thermal protection of electronic devices. Shaping these materials into microspheres for additional fascinating properties is efficient but challenging. In this regard, a novel phase change microsphere with the design for electrical-regulation and thermal storage/release properties was fabricated via the combination of monodispersed graphene aerogel microsphere (GAM) and phase change paraffin. A programmable method, i.e., coupling ink jetting-liquid marbling-supercritical drying (ILS) techniques, was demonstrated to produce monodispersed graphene aerogel microspheres (GAMs) with precise size-control. The resulting GAMs showed ultralow density, low electrical resistance, and high specific surface area with only ca. 5% diameter variation coefficient, and exhibited promising performance in smart switches. The phase change microspheres were obtained by capillary filling of phase change paraffin inside the GAMs and exhibited excellent properties, such as low electrical resistance, high latent heat, well sphericity, and thermal buffering. Assembling the phase change microsphere into the microcircuit, we found that this tiny device was quite sensitive and could respond to heat as low as 0.027 J.

Thermally stable, low resistance contact systems for use with shallow junction p(+) nn(+) and n(+)pp(+) InP solar cells

NASA Technical Reports Server (NTRS)

Weizer, V. G.; Fatemi, N. S.; Hoffman, R. W.

1995-01-01

Two contact systems for use on shallow junction InP solar cells are described. The feature shared by these two contact systems is the absence of the metallurgical intermixing that normally takes place between the semiconductor and the contact metallization during the sintering process. The n(+)pp(+) cell contact system, consisting of a combination of Au and Ge, not only exhibits very low resistance in the as-fabricated state, but also yields post-sinter resistivity values of 1(exp -7) ohms-sq cm, with effectively no metal-InP interdiffusion. The n(+)pp(+)cell contact system, consisting of a combination of Ag and Zn, permits low resistance ohmic contact to be made directly to a shallow junction p/n InP device without harming the device itself during the contacting process.

The Improvement of the Resistance to Candida albicans and Trichophyton interdigitale of Some Woven Fabrics Based on Cotton.

PubMed

Surdu, Lilioara; Stelescu, Maria Daniela; Manaila, Elena; Nicula, Gheorghe; Iordache, Ovidiu; Dinca, Laurentiu Christian; Berechet, Mariana-Daniela; Vamesu, Mariana; Gurau, Dana

2014-01-01

This paper presents the improvement of the antimicrobial character of woven fabrics based on cotton. The woven fabrics were cleaned in oxygen plasma and treated by padding with silver chloride and titanium dioxide particles. The existence of silver and titanium on woven fabrics was evidenced by electronic microscope images (SEM, EDAX) and by flame atomic absorption spectrophotometry. The antimicrobial tests were performed with two fungi: Candida albicans and Trichophyton interdigitale. The obtained antimicrobial effect was considerably higher compared to the raw fabrics. Treatment of dyed fabrics with a colloidal solution based on silver chloride and titanium dioxide particles does not considerably influence colour resistance of dyes.

The Improvement of the Resistance to Candida albicans and Trichophyton interdigitale of Some Woven Fabrics Based on Cotton

PubMed Central

Stelescu, Maria Daniela; Manaila, Elena; Nicula, Gheorghe; Iordache, Ovidiu; Dinca, Laurentiu Christian; Berechet, Mariana-Daniela; Vamesu, Mariana; Gurau, Dana

2014-01-01

This paper presents the improvement of the antimicrobial character of woven fabrics based on cotton. The woven fabrics were cleaned in oxygen plasma and treated by padding with silver chloride and titanium dioxide particles. The existence of silver and titanium on woven fabrics was evidenced by electronic microscope images (SEM, EDAX) and by flame atomic absorption spectrophotometry. The antimicrobial tests were performed with two fungi: Candida albicans and Trichophyton interdigitale. The obtained antimicrobial effect was considerably higher compared to the raw fabrics. Treatment of dyed fabrics with a colloidal solution based on silver chloride and titanium dioxide particles does not considerably influence colour resistance of dyes. PMID:25276112

Fabrication of high-performance InGaZnOx thin film transistors based on control of oxidation using a low-temperature plasma

NASA Astrophysics Data System (ADS)

Takenaka, Kosuke; Endo, Masashi; Uchida, Giichiro; Setsuhara, Yuichi

2018-04-01

This work demonstrated the low-temperature control of the oxidation of Amorphous InGaZnOx (a-IGZO) films using inductively coupled plasma as a means of precisely tuning the properties of thin film transistors (TFTs) and as an alternative to post-deposition annealing at high temperatures. The effects of the plasma treatment of the as-deposited a-IGZO films were investigated by assessing the electrical properties of TFTs incorporating these films. A TFT fabricated using an a-IGZO film exposed to an Ar-H2-O2 plasma at substrate temperatures as low as 300 °C exhibited the best performance, with a field effect mobility as high as 42.2 cm2 V-1 s-1, a subthreshold gate voltage swing of 1.2 V decade-1, and a threshold voltage of 2.8 V. The improved transfer characteristics of TFTs fabricated with a-IGZO thin films treated using an Ar-H2-O2 plasma are attributed to the termination of oxygen vacancies around Ga and Zn atoms by OH radicals in the gas phase.

Environmental resistance of oxide tags fabricated on 304L stainless steel via nanosecond pulsed laser irradiation

DOE PAGES

Lawrence, Samantha Kay; Adams, David P.; Bahr, David F.; ...

2015-11-14

Nanosecond pulsed laser irradiation was used to fabricate colored, mechanically robust oxide “tags” on 304L stainless steel. Immersion in simulated seawater solution, salt fog exposure, and anodic polarization in a 3.5% NaCl solution were employed to evaluate the environmental resistance of these oxide tags. Single layer oxides outside a narrow thickness range (~ 100–150 nm) are susceptible to dissolution in chloride containing environments. The 304L substrates immediately beneath the oxides corrode severely—attributed to Cr-depletion in the melt zone during laser processing. For the first time, multilayered oxides were fabricated with pulsed laser irradiation in an effort to expand the protectivemore » thickness range while also increasing the variety of film colors attainable in this range. Layered films grown using a laser scan rate of 475 mm/s are more resistant to both localized and general corrosion than oxides fabricated at 550 mm/s. Furthermore, in the absence of pre-processing to mitigate Cr-depletion, layered films can enhance environmental stability of the system.« less

Fabrication of Water Jet Resistant and Thermally Stable Superhydrophobic Surfaces by Spray Coating of Candle Soot Dispersion.

PubMed

Qahtan, Talal F; Gondal, Mohammed A; Alade, Ibrahim O; Dastageer, Mohammed A

2017-08-08

A facile synthesis method for highly stable carbon nanoparticle (CNP) dispersion in acetone by incomplete combustion of paraffin candle flame is presented. The synthesized CNP dispersion is the mixture of graphitic and amorphous carbon nanoparticles of the size range of 20-50 nm and manifested the mesoporosity with an average pore size of 7 nm and a BET surface area of 366 m 2 g -1 . As an application of this material, the carbon nanoparticle dispersion was spray coated (spray-based coating) on a glass surface to fabricate superhydrophobic (water contact angle > 150° and sliding angle < 10 °) surfaces. The spray coated surfaces were found to exhibit much improved water jet resistance and thermal stability up to 400 °C compared to the surfaces fabricated from direct candle flame soot deposition (candle-based coating). This study proved that water jet resistant and thermally stable superhydrophobic surfaces can be easily fabricated by simple spray coating of CNP dispersion gathered from incomplete combustion of paraffin candle flame and this technique can be used for different applications with the potential for the large scale fabrication.

Ignition characteristics of some aircraft interior fabrics

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Brandt, D. L.

1978-01-01

Six samples of aircraft interior fabrics were evaluated with regard to resistance to ignition by radiant heat. Five samples were aircraft seat upholstery fabrics and one sample was an aircraft curtain fabric. The aircraft seat fabrics were 100% wool (2 samples), 83% wool/17% nylon, 49% wool/51% polyvinyl chloride, and 100% rayon. The aircraft curtain fabric was 92% modacrylic/8% polyester. The five samples of aircraft seat upholstery fabrics were also evaluated with regard to resistance to ignition by a smoldering cigarette. The four samples of wool-containing aircraft seat fabrics appeared to be superior to the sample of rayon seat fabric in resistance to ignition, both by radiant heat and by a smoldering cigarette.

Fabrication of 3D polymer photonic crystals for near-IR applications

NASA Astrophysics Data System (ADS)

Yao, Peng; Qiu, Liang; Shi, Shouyuan; Schneider, Garrett J.; Prather, Dennis W.; Sharkawy, Ahmed; Kelmelis, Eric

2008-02-01

Photonic crystals[1, 2] have stirred enormous research interest and became a growing enterprise in the last 15 years. Generally, PhCs consist of periodic structures that possess periodicity comparable with the wavelength that the PhCs are designed to modulate. If material and periodic pattern are properly selected, PhCs can be applied to many applications based on their unique properties, including photonic band gaps (PBG)[3], self-collimation[4], super prism[5], etc. Strictly speaking, PhCs need to possess periodicity in three dimensions to maximize their advantageous capabilities. However, many current research is based on scaled two-dimensional PhCs, mainly due to the difficulty of fabrication such three-dimensional PhCs. Many approaches have been explored for the fabrication of 3D photonic crystals, including layer-by-layer surface micromachining[6], glancing angle deposition[7], 3D micro-sculpture method[8], self-assembly[9] and lithographical methods[10-12]. Among them, lithographic methods became increasingly accepted due to low costs and precise control over the photonic crystal structure. There are three mostly developed lithographical methods, namely X-ray lithography[10], holographic lithography[11] and two-photon polymerization[12]. Although significant progress has been made in developing these lithography-based technologies, these approaches still suffer from significant disadvantages. X-ray lithography relies on an expensive radiation source. Holographic lithography lacks the flexibility to create engineered defects, and multi-photon polymerization is not suitable for parallel fabrication. In our previous work, we developed a multi-layer photolithography processes[13, 14] that is based on multiple resist application and enhanced absorption upon exposure. Using a negative lift-off resist (LOR) and 254nm DUV source, we have demonstrated fabrication of 3D arbitrary structures with feature size of several microns. However, severe intermixing problem

Design and fabrication of a 900-1700 nm hyper-spectral imaging spectrometer

NASA Astrophysics Data System (ADS)

Kim, Tae Hyoung; Kong, Hong Jin; Kim, Tae Hoon; Shin, Jae Sung

2010-02-01

This paper presents a 900-1700 nm hyper-spectral imaging spectrometer which offers low distortions, a low F-number, a compact size, an easily-fabricated design and a low cost (is presented in this paper). The starting point for its optical design is discussed according to the geometrical aberration theory and Rowland circle condition. It is shown that these methods are useful in designing a push-broom hyper-spectral imaging spectrometer that has an aperture of f/2.4, modulation transfer functions of less than 0.8 at 25 cycles/mm, and spot sizes less than 10 μm. A prototype of the optimized hyper-spectral imaging spectrometer has been fabricated using a high precision machine and the experimental demonstration with the fabricated hyper-spectral imaging spectrometer is presented.

Development of low cost fabrication techniques for large solid rocket nozzles

NASA Technical Reports Server (NTRS)

Warga, J. J.

1971-01-01

Property measurements and fabrication characteristics were determined and the performance in subscale (Minuteman Wing 2 second stage) motors was evaluated. It was demonstrated that the incorporation of low cost fabrication techniques in a full scale 260 in. nozzle could result in savings of $149,000 when compared with an identical design using tape-wrapped components throughout.

Fabric defect detection based on visual saliency using deep feature and low-rank recovery

NASA Astrophysics Data System (ADS)

Liu, Zhoufeng; Wang, Baorui; Li, Chunlei; Li, Bicao; Dong, Yan

2018-04-01

Fabric defect detection plays an important role in improving the quality of fabric product. In this paper, a novel fabric defect detection method based on visual saliency using deep feature and low-rank recovery was proposed. First, unsupervised training is carried out by the initial network parameters based on MNIST large datasets. The supervised fine-tuning of fabric image library based on Convolutional Neural Networks (CNNs) is implemented, and then more accurate deep neural network model is generated. Second, the fabric images are uniformly divided into the image block with the same size, then we extract their multi-layer deep features using the trained deep network. Thereafter, all the extracted features are concentrated into a feature matrix. Third, low-rank matrix recovery is adopted to divide the feature matrix into the low-rank matrix which indicates the background and the sparse matrix which indicates the salient defect. In the end, the iterative optimal threshold segmentation algorithm is utilized to segment the saliency maps generated by the sparse matrix to locate the fabric defect area. Experimental results demonstrate that the feature extracted by CNN is more suitable for characterizing the fabric texture than the traditional LBP, HOG and other hand-crafted features extraction method, and the proposed method can accurately detect the defect regions of various fabric defects, even for the image with complex texture.

Voltage controlling mechanisms in low resistivity silicon solar cells: A unified approach

NASA Technical Reports Server (NTRS)

Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

1984-01-01

An experimental technique capable of resolving the dark saturation current into its base and emitter components is used as the basis of an analysis in which the voltage limiting mechanisms were determined for a variety of high voltage, low resistivity silicon solar cells. The cells studied include the University of Florida hi-low emitter cell, the NASA and the COMSAT multi-step diffused cells, the Spire Corporation ion-implanted emitter cell, and the University of New South Wales MINMIS and MINP cells. The results proved to be, in general, at variance with prior expectations. Most surprising was the finding that the MINP and the MINMIS voltage improvements are due, to a considerable extent, to a previously unrecognized optimization of the base component of the saturation current. This result is substantiated by an independent analysis of the material used to fabricate these devices.

Voltage controlling mechanisms in low resistivity silicon solar cells - A unified approach

NASA Technical Reports Server (NTRS)

Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

1984-01-01

An experimental technique capable of resolving the dark saturation current into its base and emitter components is used as the basis of an analysis in which the voltage limiting mechanisms were determined for a variety of high voltage, low resistivity silicon solar cells. The cells studied include the University of Florida hi-low emitter cell, the NASA and the COMSAT multi-step diffused cells, the Spire Corporation ion-implanted emitter cell, and the University of New South Wales MINMIS and MINP cells. The results proved to be, in general, at variance with prior expectations. Most surprising was the finding that the MINP and the MINMIS voltage improvements are due, to a considerable extent, to a previously unrecognized optimization of the base component of the saturation current. This result is substantiated by an independent analysis of the material used to fabricate these devices.

The Stability and Oxidation Resistance of Iron- and Cobalt-Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation

DTIC Science & Technology

2005-01-01

imaging, drug delivery, and hyperthermia treatment for cancer . Ideal magnetic nanoparticle fluids have well-separated, biocompatible nanoparticles with a...Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation DISTRIBUTION: Approved for public release, distribution unlimited This paper...Oxidation Resistance of Iron- and Cobalt-Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation Nguyen H. Hail, Raymond Lemoine’, Shaina

All-optical lithography process for contacting nanometer precision donor devices

NASA Astrophysics Data System (ADS)

Ward, D. R.; Marshall, M. T.; Campbell, D. M.; Lu, T. M.; Koepke, J. C.; Scrymgeour, D. A.; Bussmann, E.; Misra, S.

2017-11-01

We describe an all-optical lithography process that can make electrical contact to nanometer-precision donor devices fabricated in silicon using scanning tunneling microscopy (STM). This is accomplished by implementing a cleaning procedure in the STM that allows the integration of metal alignment marks and ion-implanted contacts at the wafer level. Low-temperature transport measurements of a patterned device establish the viability of the process.

Electromagnetic microforging apparatus for low-cost fabrication of molds for microlens arrays

NASA Astrophysics Data System (ADS)

Pribošek, Jaka; Diaci, Janez

2015-06-01

This study addresses the problem of low-cost microlens fabrication and outlines the development of a novel microforging apparatus for microlens mold fabrication. The apparatus consists of an electromagnetic impact tool which strikes a piston with a hardened steel ball into a workpiece. The impact creates a spherical indentation which serves as a lens cavity. The microforging apparatus is controlled by a microprocessor control unit communicating with a personal computer and enables on-the-fly variation of electromagnetic excitation to control the microforging process. We studied the effects of process parameters on the diameter of the fabricated lens cavities inspected by a custom automatic image processing algorithm. Different microforging regimes are analyzed and discussed. The surface quality of fabricated cavities has been inspected by confocal microscopy and the influence of fill factor on sphericity error has been studied. The proposed microforging method enables the fabrication of molds with 100% fill factor, surface roughness as low as Ra 0.15 µm and sphericity error lower than 0.5 µm. The fabricated microlens arrays exhibit nearly diffraction-limited performance, offering a wide range of possible applications. We believe this study provides access to microoptical technology for smaller optical and computer vision laboratories.

Fabrication of sinterable silicon nitride by injection molding

NASA Technical Reports Server (NTRS)

Quackenbush, C. L.; French, K.; Neil, J. T.

1982-01-01

Transformation of structural ceramics from the laboratory to production requires development of near net shape fabrication techniques which minimize finish grinding. One potential technique for producing large quantities of complex-shaped parts at a low cost, and microstructure of sintered silicon nitride fabricated by injection molding is discussed and compared to data generated from isostatically dry-pressed material. Binder selection methodology, compounding of ceramic and binder components, injection molding techniques, and problems in binder removal are discussed. Strength, oxidation resistance, and microstructure of sintered silicon nitride fabricated by injection molding is discussed and compared to data generated from isostatically dry-pressed material.

Low Cost Precision Lander for Lunar Exploration

NASA Astrophysics Data System (ADS)

Head, J. N.; Gardner, T. G.; Hoppa, G. V.; Seybold, K. G.

2004-12-01

For 60 years the US Defense Department has invested heavily in producing small, low mass, precision guided vehicles. The technologies matured under these programs include terrain-aided navigation, closed loop terminal guidance algorithms, robust autopilots, high thrust-to-weight propulsion, autonomous mission management software, sensors, and data fusion. These technologies will aid NASA in addressing New Millennium Science and Technology goals as well as the requirements flowing from the Vision articulated in January 2004. Establishing and resupplying a long term lunar presence will require automated landing precision not yet demonstrated. Precision landing will increase safety and assure mission success. In the DOD world, such technologies are used routinely and reliably. Hence, it is timely to generate a point design for a precise planetary lander useful for lunar exploration. In this design science instruments amount to 10 kg, 16% of the lander vehicle mass. This compares favorably with 7% for Mars Pathfinder and less than 15% for Surveyor. The mission design flies the lander in an inert configuration to the moon, relying on a cruise stage for navigation and TCMs. The lander activates about a minute before impact. A solid booster reduces the vehicle speed to 300-450 m/s. The lander is now about 2 minutes from touchdown and has 600 to 700 m/s delta-v capability, allowing for about 10 km of vehicle divert during terminal descent. This concept of operations is chosen because it closely mimics missile operational timelines used for decades: the vehicle remains inert in a challenging environment, then must execute its mission flawlessly on a moment's notice. The vehicle design consists of a re-plumbed propulsion system, using propellant tanks and thrusters from exoatmospheric programs. A redesigned truss provides hard points for landing gear, electronics, power supply, and science instruments. A radar altimeter and a Digital Scene Matching Area Correlator (DSMAC

Materials Design of the Codoping for the Fabrication of Low-Resistivity p-Type ZnSe and GaN by ab-initio Electronic Structure Calculation

NASA Astrophysics Data System (ADS)

Katayama-Yoshida, H.; Yamamoto, T.

1997-08-01

We propose an effective doping method, the codoping (doping with n- and p-type dopants at the same time) method, for the fabrication of low-resistivity p-type ZnSe and GaN with wide-band-gap based upon ab-initio electronic band structure calculations. p-type doping eminently leads to an increase in the electrostatic energy, called the Madelung energy, which shifts the Se 4p levels for p-type doped ZnSe and the N 2p levels for p-type doped GaN materials towards higher energy regions. This leads to a destabilization of ionic charge distributions in p-type ZnSe and p-type GaN crystals, resulting in the self-compensation of anion intrinsic defects. For ZnSe crystals, we propose the codoping of n-type In donors at Zn sites and p-type N acceptors at Se sites based on the calculation. In addition, we propose the codoping of n-type Si-donors at Ga sites (n-type O donors at N sites) and p-type Be- or Mg acceptors at Ga sites. The codoping decreases the Madelung energy and leads to an increase in the net acceptor carrier density.

Fabrication and characterization of a phosphosilicate YDF with high Yb absorbance and low background loss

NASA Astrophysics Data System (ADS)

Kim, Seong-Jin; Hujimaki, Yosuke; Taniguchi, Hirokazu; Kinoshita, Hiroaki; Sato, Kenji

2014-03-01

In this paper, we report fabrication and investigation of ytterbium-doped phosphorsilicate fiber (P co-doped YDF) with high Yb content, low numerical aperture, and low background loss. The P co-doped YDF is fabricated by MCVD using the vapor sources of Yb, SiCl4, AlCl3, and POCl3, and by the gas-phase doping method. The optical properties of this P co-doped YDF are compared with Al co-doped and Al:P co-doped YDFs with low background losses. The minimum background loss of the P co-doped YDF in the spectral range from 1100 to 1380 nm is as low as ~3 dB/km. This is nearly independent of the Yb and P contents because soot deposition and collapsing conditions are properly optimized (i.e., the P co-doped YDF from a non-optimized process shows a few hundred dB/km). The excess loss induced by PD, for the P co-doped YDF, was dramatically reduced compared to both Al co-doped and Al:P co-doped YDFs. The optical slope efficiency of the P co-doped YDF is about 80%, depending on the pumping wavelength and fiber length. The fiber colors during pumping are blue for both the P co-doped and Al:P co-doped YDFs. Based on the results from a prolonged test, the output power of the P co-doped YDF is highly stable, with an initial degradation of 2-3%; which demonstrate improvement in PD resistivity with P incorporation into the glass, compared to the Al:P co-doped YDF with degradation above 6%.

Fabrication of carbon quantum dots with nano-defined position and pattern in one step via sugar-electron-beam writing.

PubMed

Weng, Yuyan; Li, Zhiyun; Peng, Lun; Zhang, Weidong; Chen, Gaojian

2017-12-14

Quantum dots (QDs) are promising materials in nanophotonics, biological imaging, and even quantum computing. Precise positioning and patterning of QDs is a prerequisite for realizing their actual applications. Contrary to the traditional two discrete steps of fabricating and positioning QDs, herein, a novel sugar-electron-beam writing (SEW) method is reported for producing QDs via electron-beam lithography (EBL) that uses a carefully chosen synthetic resist, poly(2-(methacrylamido)glucopyranose) (PMAG). Carbon QDs (CQDs) could be fabricated in situ through electron beam exposure, and the nanoscale position and luminescence intensity of the produced CQDs could be precisely controlled without the assistance of any other fluorescent matter. We have demonstrated that upon combining an electron beam with a glycopolymer, in situ production of CQDs occurs at the electron beam spot center with nanoscale precision at any place and with any patterns, an advancement that we believe will stimulate innovations in future applications.

Fabrication of low cost soft tissue prostheses with the desktop 3D printer

NASA Astrophysics Data System (ADS)

He, Yong; Xue, Guang-Huai; Fu, Jian-Zhong

2014-11-01

Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.

Fabrication of low cost soft tissue prostheses with the desktop 3D printer.

PubMed

He, Yong; Xue, Guang-huai; Fu, Jian-zhong

2014-11-27

Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.

Compact Submillimeter-Wave Receivers Made with Semiconductor Nano-Fabrication Technologies

NASA Technical Reports Server (NTRS)

Jung, C.; Thomas, B.; Lee, C.; Peralta, A.; Chattopadhyay, G.; Gill, J.; Cooper, K.; Mehdi, I.

2011-01-01

Advanced semiconductor nanofabrication techniques are utilized to design, fabricate and demonstrate a super-compact, low-mass (<10 grams) submillimeter-wave heterodyne front-end. RF elements such as waveguides and channels are fabricated in a silicon wafer substrate using deep-reactive ion etching (DRIE). Etched patterns with sidewalls angles controlled with 1 deg precision are reported, while maintaining a surface roughness of better than 20 nm rms for the etched structures. This approach is being developed to build compact 2-D imaging arrays in the THz frequency range.

Low resistance contacts for shallow junction semiconductors

NASA Technical Reports Server (NTRS)

Fatemi, Navid S. (Inventor); Weizer, Victor G. (Inventor)

1994-01-01

A method of enhancing the specific contact resistivity in InP semiconductor devices and improved devices produced thereby are disclosed. Low resistivity values are obtained by using gold ohmic contacts that contain small amounts of gallium or indium and by depositing a thin gold phosphide interlayer between the surface of the InP device and the ohmic contact. When both the thin interlayer and the gold-gallium or gold-indium contact metallizations are used, ultra low specific contact resistivities are achieved. Thermal stability with good contact resistivity is achieved by depositing a layer of refractory metal over the gold phosphide interlayer.

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.

Development of flame resistant treatment for nomex fibrous structures

NASA Technical Reports Server (NTRS)

Toy, M. S.

1978-01-01

Technology which renders aramid fibrous structures flame resistant through chemical modification was developed. The project scaled up flame resistant treatment from laboratory fabric swatches of a few inches to efficiently producing ten yards of commercial width (41 inches) aromatic polyamide. The radiation intensity problem of the processor was resolved. Further improvement of the processor cooling system was recommended for two reasons: (1) To advance current technology of flame proofing Nomex fabric to higher oxygen enriched atmospheres; and (2) To adapt the processor for direct applicability to low cost commercial fabrics.

Lab on a fabric: Mass producible and low-cost fabric filters for the high-throughput viable isolation of circulating tumor cells.

PubMed

Bu, Jiyoon; Kang, Yoon-Tae; Lee, Yong-Seok; Kim, Jeongsuk; Cho, Young-Ho; Moon, Byung-In

2017-05-15

Circulating tumor cells (CTCs) play an important role in estimating the presence and the metastatic relapse of tumor. Despite of their importance, isolation of viable CTCs is still struggling, since chemical or mechanical damages are unavoidable when separating less than 1000 of CTCs out of billions of other blood components. Furthermore, the current CTC isolation devices show low productivity, since they are produced after a series of complicated fabrication processes. Here, we present a low-cost and mass-producible fabric filters for the viable CTC isolation and the further molecular assay for profiling cancer-associated markers. The fabric filter, produced by polyester monofilament yarns, can be massively produced at extremely low-cost, by showing productivity of ~22filters/s at ~59filters/USD. By utilizing size-based sorting method, the fabric filter is capable to isolate both epithelial and mesenchymal CTCs, while slots with curved walls are beneficial for preventing the cell rupture by reducing 21.6% of mechanical stress compared to the conventional straight-walled slots. We applied our filter to 11 human blood samples and found that the number of CTCs was closely related to the expression level of Ki-67, which is highly overexpressed in proliferative tumors. The fabric filter might be an appropriate caner-screening tool in developing countries, where people suffer from insufficient healthcare services. Copyright © 2017 Elsevier B.V. All rights reserved.

Highly uniform resistive switching properties of amorphous InGaZnO thin films prepared by a low temperature photochemical solution deposition method.

PubMed

Hu, Wei; Zou, Lilan; Chen, Xinman; Qin, Ni; Li, Shuwei; Bao, Dinghua

2014-04-09

We report on highly uniform resistive switching properties of amorphous InGaZnO (a-IGZO) thin films. The thin films were fabricated by a low temperature photochemical solution deposition method, a simple process combining chemical solution deposition and ultraviolet (UV) irradiation treatment. The a-IGZO based resistive switching devices exhibit long retention, good endurance, uniform switching voltages, and stable distribution of low and high resistance states. Electrical conduction mechanisms were also discussed on the basis of the current-voltage characteristics and their temperature dependence. The excellent resistive switching properties can be attributed to the reduction of organic- and hydrogen-based elements and the formation of enhanced metal-oxide bonding and metal-hydroxide bonding networks by hydrogen bonding due to UV irradiation, based on Fourier-transform-infrared spectroscopy, X-ray photoelectron spectroscopy, and Field emission scanning electron microscopy analysis of the thin films. This study suggests that a-IGZO thin films have potential applications in resistive random access memory and the low temperature photochemical solution deposition method can find the opportunity for further achieving system on panel applications if the a-IGZO resistive switching cells were integrated with a-IGZO thin film transistors.

A very low resistance, non-sintered contact system for use on indium phosphide concentrator/shallow junction solar cells

NASA Technical Reports Server (NTRS)

Weizer, Victor G.; Fatemi, Navid S.

1991-01-01

An investigation is made into the possibility of providing low resistance contacts to shallow junction InP solar cells which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures. We show that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivity (R sub c) to the 10(exp -5) ohm cm(exp 2) range. We next consider the contact system Au/Au2P3 which has been shown to exhibit as-fabricated R sub c values in the 10(exp -6) ohm cm(exp 2) range, but which fails quickly when heated. We show that the substitution of a refractory metal (W, Ta) for Au preserves the low R sub c values while preventing the destructive reactions that would normally take place in this system at high temperatures. We show, finally, that R sub c values in the 10(exp -7) ohm cm(exp 2) range can be achieved without sintering by combining the effects of In or Ga additions to Au contacts with the effects of introducing a thin Au2P3 layer at the metal-InP interface.

A very low resistance, non-sintered contact system for use on indium phosphide concentrator/shallow junction solar cells

NASA Technical Reports Server (NTRS)

Weizer, Victor G.; Fatemi, Navid S.

1991-01-01

An investigation is made into the possibility of providing low resistance contacts to shallow junction InP solar cells which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures. We show that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivity (R sub c) to the 10(exp -5) ohm cm(exp 2) range. We next consider the contact system Au/Au2P3, which has been shown to exhibit as-fabricated R sub c values in the 10(exp -6) ohm cm(exp 2) range, but which fails quickly when heated. We show that the substitution of a refractory metal (W, Ta) for Au preserves the low R sub c values while preventing the destructive reactions that would normally take place in this system at high temperatures. We show, finally, that R sub c values in the 10(exp -7) ohm cm(exp 2) range can be achieved without sintering by combining the effects of In or Ga additions to Au contacts with the effects of introducing a thin Au2P3 layer at the metal-InP interface.

Vision-based in-line fabric defect detection using yarn-specific shape features

NASA Astrophysics Data System (ADS)

Schneider, Dorian; Aach, Til

2012-01-01

We develop a methodology for automatic in-line flaw detection in industrial woven fabrics. Where state of the art detection algorithms apply texture analysis methods to operate on low-resolved ({200 ppi) image data, we describe here a process flow to segment single yarns in high-resolved ({1000 ppi) textile images. Four yarn shape features are extracted, allowing a precise detection and measurement of defects. The degree of precision reached allows a classification of detected defects according to their nature, providing an innovation in the field of automatic fabric flaw detection. The design has been carried out to meet real time requirements and face adverse conditions caused by loom vibrations and dirt. The entire process flow is discussed followed by an evaluation using a database with real-life industrial fabric images. This work pertains to the construction of an on-loom defect detection system to be used in manufacturing practice.

All-optical lithography process for contacting nanometer precision donor devices

DOE PAGES

Ward, Daniel Robert; Marshall, Michael Thomas; Campbell, DeAnna Marie; ...

2017-11-06

In this article, we describe an all-optical lithography process that can make electrical contact to nanometer-precision donor devices fabricated in silicon using scanning tunneling microscopy (STM). This is accomplished by implementing a cleaning procedure in the STM that allows the integration of metal alignment marks and ion-implanted contacts at the wafer level. Low-temperature transport measurements of a patterned device establish the viability of the process.

All-optical lithography process for contacting nanometer precision donor devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Daniel Robert; Marshall, Michael Thomas; Campbell, DeAnna Marie

In this article, we describe an all-optical lithography process that can make electrical contact to nanometer-precision donor devices fabricated in silicon using scanning tunneling microscopy (STM). This is accomplished by implementing a cleaning procedure in the STM that allows the integration of metal alignment marks and ion-implanted contacts at the wafer level. Low-temperature transport measurements of a patterned device establish the viability of the process.

Fabric strain sensor integrated with CNPECs for repeated large deformation

NASA Astrophysics Data System (ADS)

Yi, Weijing

Flexible and soft strain sensors that can be used in smart textiles for wearable applications are much desired. They should meet the requirements of low modulus, large working range and good fatigue resistance as well as good sensing performances. However, there were no commercial products available and the objective of the thesis is to investigate fabric strain sensors based on carbon nanoparticle (CNP) filled elastomer composites (CNPECs) for potential wearing applications. Conductive CNPECs were fabricated and investigated. The introduction of silicone oil (SO) significantly decreased modulus of the composites to less than 1 MPa without affecting their deformability and they showed good stability after heat treatment. With increase of CNP concentration, a percolation appeared in electrical resistivity and the composites can be divided into three ranges. I-V curves and impedance spectra together with electro-mechanical studies demonstrated a balance between sensitivity and working range for the composites with CNP concentrations in post percolation range, and were preferred for sensing applications only if the fatigue life was improved. Due to the good elasticity and failure resist property of knitted fabric under repeated extension, it was adopted as substrate to increase the fatigue life of the conductive composites. After optimization of processing parameters, the conductive fabric with CNP concentration of 9.0CNP showed linear I-V curves when voltage is in the range of -1 V/mm and 1 V/mm and negligible capacitive behavior when frequency below 103 Hz even with strain of 60%. It showed higher sensitivity due to the combination of nonlinear resistance-strain behavior of the CNPECs and non-even strain distribution of knitted fabric under extension. The fatigue life of the conductive fabric was greatly improved. Extended on the studies of CNPECs and the coated conductive fabrics, a fabric strain sensor was designed, fabricated and packaged. The Young's modulus of

'Fab-chips': a versatile, fabric-based platform for low-cost, rapid and multiplexed diagnostics.

PubMed

Bhandari, Paridhi; Narahari, Tanya; Dendukuri, Dhananjaya

2011-08-07

Low cost and scalable manufacture of lab-on-chip devices for applications such as point-of-care testing is an urgent need. Weaving is presented as a unified, scalable and low-cost platform for the manufacture of fabric chips that can be used to perform such testing. Silk yarns with different properties are first selected, treated with the appropriate reagent solutions, dried and handloom-woven in one step into an integrated fabric chip. This platform has the unique advantage of scaling up production using existing and low cost physical infrastructure. We have demonstrated the ability to create pre-defined flow paths in fabric by using wetting and non-wetting silk yarns and a Jacquard attachment in the loom. Further, we show that yarn parameters such as the yarn twist frequency and weaving coverage area may be conveniently used to tune both the wicking rate and the absorptive capacity of the fabric. Yarns optimized for their final function were used to create an integrated fabric chip containing reagent-coated yarns. Strips of this fabric were then used to perform a proof-of-concept immunoassay with sample flow taking place by capillary action and detection being performed by a visual readout. This journal is © The Royal Society of Chemistry 2011

The bipolar silicon microstrip detector: A proposal for a novel precision tracking device

NASA Astrophysics Data System (ADS)

Horisberger, R.

1990-03-01

It is proposed to combine the technology of fully depleted silicon microstrip detectors fabricated on n doped high resistivity silicon with the concept of the bipolar transistor. This is done by adding a n ++ doped region inside the normal p + implanted region of the reverse biased p + n diode. Teh resulting structure has amplifying properties and is referred to as bipolar pixel transistor. The simplest readout scheme of a bipolar pixel array by an aluminium strip bus leads to the bipolar microstrip detector. The bipolar pixel structure is expected to give a better signal-to-noise performance for the detection of minimum ionizing charged particle tracks than the normal silicon diode strip detector and therefore should allow in future the fabrication of thinner silicon detectors for precision tracking.

Non-destructive, ultra-low resistance, thermally stable contacts for use on shallow junction InP solar cells

NASA Technical Reports Server (NTRS)

Weizer, V. G.; Fatemi, N. S.; Korenyi-Both, A. L.

1993-01-01

Contact formation to InP is plagued by violent metal-semiconductor intermixing that takes place during the contact sintering process. Because of this the InP solar cell cannot be sintered after contact deposition. This results in cell contact resistances that are orders of magnitude higher than those that could be achieved if sintering could be performed in a non-destructive manner. We report here on a truly unique contact system involving Au and Ge, which is easily fabricated, which exhibits extremely low values of contact resistivity, and in which there is virtually no metal-semiconductor interdiffusion, even after extended sintering. We present a description of this contact system and suggest possible mechanisms to explain the observed behavior.

Impeller Creation at the Fabrication Shop

NASA Image and Video Library

1950-10-21

A mechanic and apprentice work on a wooden impeller in the Fabrication Shop at the NACA Lewis Flight Propulsion Laboratory. The 260-person Fabrication Division created almost all of the equipment and models used at the laboratory. The Technical Services Building, referred to as the “Fab Shop”, contained a number of specialized shops in the 1940s and 1950s. These included a Machine Shop, Sheet Metal Shop, Wood and Pattern Shop, Instrument Shop, Thermocouple Shop, Heat Treating Shop, Metallurgical Laboratory, and Fabrication Office. The Machine Shop fabricated research equipment not commercially available. During World War II these technicians produced high-speed cameras for combustion research, impellers and other supercharger components, and key equipment for the lab’s first supersonic wind tunnel. The Wood and Pattern Shop created everything from control panels and cabinets to aircraft model molds for sheet metal work. The Sheet Metal Shop had the ability to work with 0.01 to 4-inches thick steel plates. The Instrument Shop specialized in miniature parts and instrumentation, while the Thermocouple Shop standardized the installation of pitot tubes and thermocouples. The Metallurgical Laboratory contained a control lab for the Heat Treating Shop and a service lab for the NACA Lewis research divisions. The Heat Treating Shop heated metal parts to optimize their physical properties and contained a Precision Castings Foundry to manufacture equipment made of heat resisting alloys.

Understanding and development of manufacturable screen-printed contacts on high sheet-resistance emitters for low-cost silicon solar cells

NASA Astrophysics Data System (ADS)

Hilali, Mohamed M.

2005-11-01

A simple cost-effective approach was proposed and successfully employed to fabricate high-quality screen-printed (SP) contacts to high sheet-resistance emitters (100 O/sq) to improve the Si solar cell efficiency. Device modeling was used to quantify the performance enhancement possible from the high sheet-resistance emitter for various cell designs. It was found that for performance enhancement from the high sheet-resistance emitter, certain cell design criteria must be satisfied. Model calculations showed that in order to achieve any performance enhancement over the conventional ˜40 O/sq emitter, the high sheet resistance emitter solar cell must have a reasonably good (<120,000 cm/s) or low front-surface recombination velocity (FSRV). Model calculations were also performed to establish requirements for high fill factors (FFs). The results showed that the series resistance should be less than 0.8 O-cm2, the shunt resistance should be greater than 1000 O-cm2, and the junction leakage current should be less than 25 nA/cm2. Analytical microscopy and surface analysis techniques were used to study the Ag-Si contact interface of different SP Ag pastes. Physical and electrical properties of SP Ag thick-film contacts were studied and correlated to understand and achieve good-quality ohmic contacts to high sheet-resistance emitters for solar cells. This information was then used to define the criteria for high-quality screen-printed contacts. The role of paste constituents and firing scheme on contact quality were investigated to tailor the high-quality screen-printed contact interface structure that results in high performance solar cells. Results indicated that small particle size, high glass transition temperature, rapid firing and less aggressive glass frit help in producing high-quality contacts. Based on these results high-quality SP contacts with high FFs > 0.78 on high sheet-resistance emitters were achieved for the first time using a simple single-step firing

Precision pointing and control of flexible spacecraft

NASA Technical Reports Server (NTRS)

Bantell, M. H., Jr.

1987-01-01

The problem and long term objectives for the precision pointing and control of flexible spacecraft are given. The four basic objectives are stated in terms of two principle tasks. Under Task 1, robust low order controllers, improved structural modeling methods for control applications and identification methods for structural dynamics are being developed. Under Task 2, a lab test experiment for verification of control laws and system identification algorithms is being developed. For Task 1, work has focused on robust low order controller design and some initial considerations for structural modeling in control applications. For Task 2, work has focused on experiment design and fabrication, along with sensor selection and initial digital controller implementation. Conclusions are given.

Design and fabrication of vibration based energy harvester using microelectromechanical system piezoelectric cantilever for low power applications.

PubMed

Kim, Moonkeun; Lee, Sang-Kyun; Yang, Yil Suk; Jeong, Jaehwa; Min, Nam Ki; Kwon, Kwang-Ho

2013-12-01

We fabricated dual-beam cantilevers on the microelectromechanical system (MEMS) scale with an integrated Si proof mass. A Pb(Zr,Ti)O3 (PZT) cantilever was designed as a mechanical vibration energy-harvesting system for low power applications. The resonant frequency of the multilayer composition cantilevers were simulated using the finite element method (FEM) with parametric analysis carried out in the design process. According to simulations, the resonant frequency, voltage, and average power of a dual-beam cantilever was 69.1 Hz, 113.9 mV, and 0.303 microW, respectively, at optimal resistance and 0.5 g (gravitational acceleration, m/s2). Based on these data, we subsequently fabricated cantilever devices using dual-beam cantilevers. The harvested power density of the dual-beam cantilever compared favorably with the simulation. Experiments revealed the resonant frequency, voltage, and average power density to be 78.7 Hz, 118.5 mV, and 0.34 microW, respectively. The error between the measured and simulated results was about 10%. The maximum average power and power density of the fabricated dual-beam cantilever at 1 g were 0.803 microW and 1322.80 microW cm(-3), respectively. Furthermore, the possibility of a MEMS-scale power source for energy conversion experiments was also tested.

Fabrication of low cost soft tissue prostheses with the desktop 3D printer

PubMed Central

He, Yong; Xue, Guang-huai; Fu, Jian-zhong

2014-01-01

Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods. PMID:25427880

Determination of the resistance of fabric printed with triclosan microcapsules to the action of soil micro-flora

NASA Astrophysics Data System (ADS)

Golja, B.; Forte Tavčer, P.

2017-10-01

Microcapsules with a pressure-sensitive melamine-formaldehyde wall and triclosan core were printed to 100% cotton fabric with screen printing technique. Previous research showed excellent antibacterial activity (estimated for E. Coli and S. Aureus) of such fabric, so our aim in this research was to determine its resistance to the action of microorganisms present in the soil. The soil burial test was conducted. The breaking strength of the buried samples was measured and also the scanning electron microscope analysis was done. The results showed that none of the samples are resistant to decay. It is evident from SEM micrographs that on all of the buried samples greater morphological changes occur due to the functions of the soil microflora. It can be concluded that the samples printed with triclosan microcapsules are biodegradable which is environmentally preferable.

Travelling wave resonators fabricated with low-loss hydrogenated amorphous silicon

NASA Astrophysics Data System (ADS)

Lipka, Timo; Amthor, Julia; Trieu, Hoc Khiem; Müller, Jörg

2013-05-01

Low-loss hydrogenated amorphous silicon is employed for the fabrication of various planar integrated travelling wave resonators. Microring, racetrack, and disk resonators of different dimensions were fabricated with CMOS-compatible processes and systematically investigated. The key properties of notch filter ring resonators as extinction ratio, Q-factor, free spectral range, and the group refractive index were determined for resonators of varying radius, thereby achieving critically coupled photonic systems with high extinction ratios of about 20 dB for both polarizations. Racetrack resonators that are arranged in add/drop configuration and high quality factor microdisk resonators were optically characterized, with the microdisks exhibiting Q-factors of greater than 100000. Four-channel add/drop wavelength-division multiplexing filters that are based on cascaded racetrack resonators are studied. The design, the fabrication, and the optical characterization are presented.

Development of Low-Cost Method for Fabrication of Metal Neutron Guides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engelhaupt, Darell; Khaykovich, Boris; Romaine, Suzanne

Neutron scattering is one of the most useful methods of studying the structure and dynamics of matter. US DOE neutron scattering research facilities at Oak Ridge National Laboratory are among the World’s most advanced, providing researchers with unmatched capabilities for probing the structure and properties of materials, including engineering and biological systems. This task is to develop a lower cost process to optimize and produce the required neutron guides capable of efficiently delivering neutron beams for tens of meters between neutron moderators and instruments. Therefore, our effort is to improve the performance and lower the production cost of neutron guides.more » Our approach aims at improving guide quality while controlling their rising costs by adopting a novel electroforming replication approach to their fabrication. These guides will be especially advantageous when used near the neutron source since the radiation resistance of nickel is superior to glass. Additionally, we are depositing low-stress nickel from an extremely low impurity solution completely free of stress-reducing agents, which nominally contain and impart sulfur, carbon and other elements that potentially activate in the neutron environment. This is achieved by using a pulsed periodically reversed current methodology. The best guides quote waviness of 0.1 mrad. It is reasonable to prepare just one mandrel of about 0.5 m long, for production of tens of guide segments, saving both the cost and supply time of guides to neutron facilities. We estimate that we can fabricate a single mandrel for the current cost of an individual one-meter guide, but from this, we can produce tens of meters of guide very inexpensively without mandrel refurbishment. While a multilayer coating will add to the overall cost, we expect this will be less than that of commercially available guides today. Therefore, we will produce higher quality guides, which are less susceptible to radiation damage, at the

Development of Low-Cost Method for Fabrication of Metal Neutron Guides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engelhaupt, Darell; Khaykovich, Boris; Romaine, Suzanne

2017-12-19

Neutron scattering is one of the most useful methods of studying the structure and dynamics of matter. US DOE neutron scattering research facilities at Oak Ridge National Laboratory are among the World’s most advanced, providing researchers with unmatched capabilities for probing the structure and properties of materials, including engineering and biological systems. This task is to develop a lower cost process to optimize and produce the required neutron guides capable of efficiently delivering neutron beams for tens of meters between neutron moderators and instruments. Therefore, our effort is to improve the performance and lower the production cost of neutron guides.more » Our approach aims at improving guide quality while controlling their rising costs by adopting a novel electroforming replication approach to their fabrication. These guides will be especially advantageous when used near the neutron source since the radiation resistance of nickel is superior to glass. Additionally, we are depositing low-stress nickel from an extremely low impurity solution completely free of stress-reducing agents, which nominally contain and impart sulfur, carbon and other elements that potentially activate in the neutron environment. This is achieved by using a pulsed periodically reversed current methodology. The best guides quote waviness of 0.1 mrad. It is reasonable to prepare just one mandrel of about 0.5 m long, for production of tens of guide segments, saving both the cost and supply time of guides to neutron facilities. We estimate that we can fabricate a single mandrel for the current cost of an individual one-meter guide, but from this, we can produce tens of meters of guide very inexpensively without mandrel refurbishment. While a multilayer coating will add to the overall cost, we expect this will be less than that of commercially available guides today. Therefore, we will produce higher quality guides, which are less susceptible to radiation damage, at the

Investigation of low-cost ablative heat shield fabrication for space shuttles

NASA Technical Reports Server (NTRS)

Chandler, H. H.

1972-01-01

Improvements in the processes and design to reduce the manufacturing costs for low density ablative panels for the space shuttle are discussed. The areas that were studied included methods of loading honeycomb core, alternative reinforcement concepts, and the use of reusable subpanels. A review of previous studies on the fabrication of low-cost ablative panels and on permissible defects that do not affect thermal performance was conducted. Considerable differences in the quoted prices for ablative panels, even though the various contractors had reported similar fabrication times were discovered. How these cost differences arise from different estimating criteria and which estimating assumptions and other costs must be included in order to arrive at a realistic price are discussed.

Design and Fabrication of a Precision Template for Spine Surgery Using Selective Laser Melting (SLM).

PubMed

Wang, Di; Wang, Yimeng; Wang, Jianhua; Song, Changhui; Yang, Yongqiang; Zhang, Zimian; Lin, Hui; Zhen, Yongqiang; Liao, Suixiang

2016-07-22

In order to meet the clinical requirements of spine surgery, this paper proposes the fabrication of the customized template for spine surgery through computer-aided design. A 3D metal printing-selective laser melting (SLM) technique was employed to directly fabricate the 316L stainless steel template, and the metal template with tiny locating holes was used as an auxiliary tool to insert spinal screws inside the patient's body. To guarantee accurate fabrication of the template for cervical vertebra operation, the contact face was placed upwards to improve the joint quality between the template and the cervical vertebra. The joint surface of the printed template had a roughness of Ra = 13 ± 2 μm. After abrasive blasting, the surface roughness was Ra = 7 ± 0.5 μm. The surgical metal template was bound with the 3D-printed Acrylonitrile Butadiene Styrene (ABS) plastic model. The micro-hardness values determined at the cross-sections of SLM-processed samples varied from HV0.3 250 to HV0.3 280, and the measured tensile strength was in the range of 450 MPa to 560 MPa, which showed that the template had requisite strength. Finally, the metal template was clinically used in the patient's surgical operation, and the screws were inserted precisely as the result of using the auxiliary template. The geometrical parameters of the template hole (e.g., diameter and wall thickness) were optimized, and measures were taken to optimize the key geometrical units (e.g., hole units) in metal 3D printing. Compared to the traditional technology of screw insertion, the use of the surgical metal template enabled the screws to be inserted more easily and accurately during spinal surgery. However, the design of the high-quality template should fully take into account the clinical demands of surgeons, as well as the advice of the designing engineers and operating technicians.

Facile fabrication of a rigid and chemically resistant micromixer system from photocurable inorganic polymer by static liquid photolithography (SLP).

PubMed

Fang, Qingling; Kim, Dong-Pyo; Li, Xiaodong; Yoon, Tae-Ho; Li, Yihe

2011-08-21

Highly effective mixing in microchannels is important for most chemical reactions conducted in microfluidic chips. To obtain a rigid and chemically resistant micromixer system at low cost, we fabricated a Y-shaped microchannel with built-in mixer structures by static liquid photolithography (SLP) from methacrylated polyvinylsilazane (MPVSZ) as an inorganic polymer photoresist which was then converted to a silicate phase by hydrolysis in vaporized ammonia atmosphere at 80 °C. The microchannel incorporating herringbone mixer structures was bonded with a matching polydimethylsiloxane (PDMS) open channel which was pre-coated by perhydropolysilazane (PHPS)-based mixture, and finally treated by additional hydrolysis at room temperature to convert the PHPS layer to a silica phase. Finally, the chemical resistance of the microfluidic system with embedded micromixer was confirmed with various solvents, and the excellent mixing performance in a short mixing length of 2.3 cm was demonstrated by injecting two different colored fluids into the microchannel. This journal is © The Royal Society of Chemistry 2011

Resistive switching of Cu/Cu2O junction fabricated using simple thermal oxidation at 423 K for memristor application

NASA Astrophysics Data System (ADS)

Ani, M. H.; Helmi, F.; Herman, S. H.; Noh, S.

2018-01-01

Recently, extensive researches have been done on memristor to replace current memory storage technologies. Study on active layer of memristor mostly involving n-type semiconductor oxide such as TiO2 and ZnO. This paper highlight a simple water vapour oxidation method at 423 K to form Cu/Cu2O electronic junction as a new type of memristor. Cu2O is a p-type semiconductor oxide, was used as the active layer of memristor. Cu/Cu2O/Au memristor was fabricated by thermal oxidation of copper foil, followed by sputtering of gold. Structural, morphological and memristive properties were characterized using XRD, FESEM, and current-voltage, I-V measurement respectively. Its memristivity was indentified by pinch hysteresis loop and measurement of high resistance state (HRS) and low resistance state (LRS) of the sample. The Cu/Cu2O/Au memristor demonstrates comparable performances to previous studies using other methods.

Influences of metal ions crosslinked alginate based coatings on thermal stability and fire resistance of cotton fabrics.

PubMed

Pan, Ying; Wang, Wei; Liu, Longxiang; Ge, Hua; Song, Lei; Hu, Yuan

2017-08-15

Bio-based and phosphorus-free coating was fabricated by layer-by-layer assembly method to obtain the flame retardant cotton fabric. For the first time, the modified cotton fabrics were prepared by utilizing positively charged polyethylenimine and negatively charged alginate together with subsequent crosslinking of barium, nickel and cobalt ions. Scanning electron microscopy and energy-dispersive X-ray demonstrated that the metal ions crosslinked coating was successfully constructed on the substrate. The thermal stability and flame retardancy were investigated by thermogravimetric analysis (TGA) and horizontal flame tests. TGA results showed that the degradation of the coated cotton fabrics were retarded at high temperature and the char residue of the cotton fabrics were improved after covered with the barium, nickel and cobalt ions crosslinked coatings. Furthermore, the fire resistance of cotton-Ba sample was enhanced significantly compared with the untreated sample, as evidenced by the obvious reduction (28%) of flame spread rate and complete char residue. Finally, the washing durability of coating on the fabric was enhanced after metal ions crosslinked with alginate based coating. Copyright © 2017. Published by Elsevier Ltd.

Precision glass molding of high-resolution diffractive optical elements

NASA Astrophysics Data System (ADS)

Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans P.; Plöger, Sven; Hermerschmidt, Andreas

2016-04-01

The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techniques are more economical, since the high cost of the master can be distributed among a larger number of replicas. The lack of a suitable mold material for precision glass molding has so far prevented an industrial use. Glassy Carbon (GC) offers a high mechanical strength and high thermal strength. No anti-adhesion coatings are required in molding processes. This is clearly an advantage for high resolution, high aspect ratio microstructures, where a coating with a thickness between 10 nm and 200 nm would cause a noticeable rounding of the features. Electron-beam lithography was used to fabricate GC molds with highest precision and feature sizes from 250 nm to 2 μm. The master stamps were used for precision glass molding of a low Tg glass L-BAL42 from OHARA. The profile of the replicated glass is compared to the mold with the help of SEM images. This allows discussion of the max. aspect-ratio and min. feature size. To characterize optical performances, beamsplitting elements are fabricated and their characteristics were investigated, which are in excellent agreement to theory.

Fabrication of ultra thin anodic aluminium oxide membranes by low anodization voltages

NASA Astrophysics Data System (ADS)

Pastore, I.; Poplausks, R.; Apsite, I.; Pastare, I.; Lombardi, F.; Erts, D.

2011-06-01

Formation of ultrathin anodised aluminium oxide (AAO) membranes with high aspect ratio by Al anodization in sulphuric and oxalic acids at low potentials was investigated. Low anodization potentials ensure slow electrochemical reaction speeds and formation of AAO membranes with pore diameter and thickness below 20 nm and 70 nm respectively. Minimum time necessary for formation of continuous AAO membranes was determined. AAO membrane pore surface was covered with polymer Paraloid B72TM to transport it to the selected substrate. The fabricated ultra thin AAO membranes could be used to fabricate nanodot arrays on different surfaces.

Template-assisted fabrication of protein nanocapsules

NASA Astrophysics Data System (ADS)

Dougherty, Shelley A.; Liang, Jianyu; Kowalik, Timothy F.

2009-02-01

Bionanomaterials have recently begun to spark a great amount of interest and could potentially revolutionize biomedical research. Nanoparticles, nanocapsules, and nanotubular structures are becoming attractive options in drug and gene delivery. The size of the delivery vehicles greatly impacts cellular uptake and makes it highly desirable to precisely control the diameter and length of nanocarriers to make uniform nanoparticles at low cost. Carbon nanotubes have shown great potential within the field of drug and gene delivery. However, their insolubility and cytotoxicity could severely delay FDA approval. A desirable alternative would be to fabricate nanostructures from biomaterials such as proteins, peptides, or liposomes, which are already FDA approved. In this article we demonstrate the preparation of protein nanocapsules with both ends sealed using a template-assisted alternate immersion method combined with controlled cleaving. Glucose oxidase nanocapsules with controllable diameter, wall thickness, and length were fabricated and characterized with SEM and TEM. The biochemical activity of glucose oxidase in the form of nanocapsules after processing was confirmed using UV spectrometry. Our future work will explore proteins suitable for drug encapsulation and cellular uptake and will focus on optimizing the cleaving process to gain precise control over the length of the nanocapsules.

Low-Temperature UV-Assisted Fabrication of Metal Oxide Thin Film Transistor

NASA Astrophysics Data System (ADS)

Zhu, Shuanglin

Solution processed metal oxide semiconductors have attracted intensive attention in the last several decades and have emerged as a promising candidate for the application of thin film transistor (TFT) due to their nature of transparency, flexibility, high mobility, simple processing technique and potential low manufacturing cost. However, metal oxide thin film fabricated by solution process usually requires a high temperature (over 300 °C), which is above the glass transition temperature of some conventional polymer substrates. In order to fabricate the flexible electronic device on polymer substrates, it is necessary to find a facile approach to lower the fabrication temperature and minimize defects in metal oxide thin film. In this thesis, the electrical properties dependency on temperature is discussed and an UV-assisted annealing method incorporating Deep ultraviolet (DUV)-decomposable additives is demonstrated, which can effectively improve electrical properties solution processed metal oxide semiconductors processed at temperature as low as 220 °C. By studying a widely used indium oxide (In2O3) TFT as a model system, it is worth noted that compared with the sample without UV treatment, the linear mobility and saturation mobility of UV-annealing sample are improved by 56% and 40% respectively. Meanwhile, the subthreshold swing is decreased by 32%, indicating UV-treated device could turn on and off more efficiently. In addition to pure In2O3 film, the similar phenomena have also been observed in indium oxide based Indium-Gallium-Zinc Oxide (IGZO) system. These finding presented in this thesis suggest that the UV assisted annealing process open a new route to fabricate high performance metal oxide semiconductors under low temperatures.

High precision silicon piezo resistive SMART pressure sensor

NASA Astrophysics Data System (ADS)

Brown, Rod

2005-01-01

Instruments for test and calibration require a pressure sensor that is precise and stable. Market forces also dictate a move away from single measurand test equipment and, certainly in the case of pressure, away from single range equipment. A pressure `module' is required which excels in pressure measurement but is interchangble with sensors for other measurands. A communications interface for such a sensor has been specified. Instrument Digital Output Sensor (IDOS) that permits this interchanagability and allows the sensor to be inside or outside the measuring instrument. This paper covers the design and specification of a silicon diaphragm piezo resistive SMART sensor using this interface. A brief history of instrument sensors will be given to establish the background to this development. Design choices of the silicon doping, bridge energisation method, temperature sensing, signal conversion, data processing, compensation method, communications interface will be discussed. The physical format of the `in-instrument' version will be shown and then extended to the packaging design for the external version. Test results will show the accuracy achieved exceeds the target of 0.01%FS over a range of temperatures.

A graphene integrated highly transparent resistive switching memory device

NASA Astrophysics Data System (ADS)

Dugu, Sita; Pavunny, Shojan P.; Limbu, Tej B.; Weiner, Brad R.; Morell, Gerardo; Katiyar, Ram S.

2018-05-01

We demonstrate the hybrid fabrication process of a graphene integrated highly transparent resistive random-access memory (TRRAM) device. The indium tin oxide (ITO)/Al2O3/graphene nonvolatile memory device possesses a high transmittance of >82% in the visible region (370-700 nm) and exhibits stable and non-symmetrical bipolar switching characteristics with considerably low set and reset voltages (<±1 V). The vertical two-terminal device shows an excellent resistive switching behavior with a high on-off ratio of ˜5 × 103. We also fabricated a ITO/Al2O3/Pt device and studied its switching characteristics for comparison and a better understanding of the ITO/Al2O3/graphene device characteristics. The conduction mechanisms in high and low resistance states were analyzed, and the observed polarity dependent resistive switching is explained based on electro-migration of oxygen ions.

Low cost batch fabrication of microdevices using ultraviolet light-emitting diode photolithography technique

NASA Astrophysics Data System (ADS)

Lee, Neam Heng; Swamy, Varghese; Ramakrishnan, Narayanan

2016-01-01

Solid-state technology has enabled the use of light-emitting diodes (LEDs) in lithography systems due to their low cost, low power requirement, and higher efficiency relative to the traditional mercury lamp. Uniform irradiance distribution is essential for photolithography to ensure the critical dimension (CD) of the feature fabricated. However, light illuminated from arrays of LEDs can have nonuniform irradiance distribution, which can be a problem when using LED arrays as a source to batch-fabricate multiple devices on a large wafer piece. In this study, the irradiance distribution of an UV LED array was analyzed, and the separation distance between light source and mask optimized to obtain maximum irradiance uniformity without the use of a complex lens. Further, employing a diffuser glass enhanced the fabrication process and the CD loss was minimized to an average of 300 nm. To assess the performance of the proposed technology, batch fabrication of surface acoustic wave devices on lithium niobate substrate was carried out, and all the devices exhibited identical insertion loss of -18 dB at a resonance frequency of 39.33 MHz. The proposed low-cost UV lithography setup can be adapted in academic laboratories for research and teaching on microdevices.

Atomic precision etch using a low-electron temperature plasma

NASA Astrophysics Data System (ADS)

Dorf, L.; Wang, J.-C.; Rauf, S.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

2016-03-01

Sub-nm precision is increasingly being required of many critical plasma etching processes in the semiconductor industry. Accurate control over ion energy and ion/radical composition is needed during plasma processing to meet these stringent requirements. Described in this work is a new plasma etch system which has been designed with the requirements of atomic precision plasma processing in mind. In this system, an electron sheet beam parallel to the substrate surface produces a plasma with an order of magnitude lower electron temperature Te (~ 0.3 eV) and ion energy Ei (< 3 eV without applied bias) compared to conventional radio-frequency (RF) plasma technologies. Electron beam plasmas are characterized by higher ion-to-radical fraction compared to RF plasmas, so a separate radical source is used to provide accurate control over relative ion and radical concentrations. Another important element in this plasma system is low frequency RF bias capability which allows control of ion energy in the 2-50 eV range. Presented in this work are the results of etching of a variety of materials and structures performed in this system. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in RF plasma processing systems, even during atomic layer etch. The experiments for Si etch in Cl2 based plasmas in the aforementioned etch system show that damage can be minimized if the ion energy is kept below 10 eV. Layer-by-layer etch of Si is also demonstrated in this etch system using electrical and gas pulsing.

A Low-cost Environmental Control System for Precise Radial Velocity Spectrometers

NASA Astrophysics Data System (ADS)

Sliski, David H.; Blake, Cullen H.; Halverson, Samuel

2017-12-01

We present an environmental control system (ECS) designed to achieve milliKelvin (mK) level temperature stability for small-scale astronomical instruments. This ECS is inexpensive and is primarily built from commercially available components. The primary application for our ECS is the high-precision Doppler spectrometer MINERVA-Red, where the thermal variations of the optical components within the instrument represent a major source of systematic error. We demonstrate ±2 mK temperature stability within a 0.5 m3 thermal enclosure using resistive heaters in conjunction with a commercially available PID controller and off-the-shelf thermal sensors. The enclosure is maintained above ambient temperature, enabling rapid cooling through heat dissipation into the surrounding environment. We demonstrate peak-to-valley (PV) temperature stability of better than 5 mK within the MINERVA-Red vacuum chamber, which is located inside the thermal enclosure, despite large temperature swings in the ambient laboratory environment. During periods of stable laboratory conditions, the PV variations within the vacuum chamber are less than 3 mK. This temperature stability is comparable to the best stability demonstrated for Doppler spectrometers currently achieving m s-1 radial velocity precision. We discuss the challenges of using commercially available thermoelectrically cooled CCD cameras in a temperature-stabilized environment, and demonstrate that the effects of variable heat output from the CCD camera body can be mitigated using PID-controlled chilled water systems. The ECS presented here could potentially provide the stable operating environment required for future compact “astrophotonic” precise radial velocity (PRV) spectrometers to achieve high Doppler measurement precision with a modest budget.

Conductance switching in Ag(2)S devices fabricated by in situ sulfurization.

PubMed

Morales-Masis, M; van der Molen, S J; Fu, W T; Hesselberth, M B; van Ruitenbeek, J M

2009-03-04

We report a simple and reproducible method to fabricate switchable Ag(2)S devices. The alpha-Ag(2)S thin films are produced by a sulfurization process after silver deposition on an Si substrate. Structure and composition of the Ag(2)S are characterized using XRD and RBS. Our samples show semiconductor behaviour at low bias voltages, whereas they exhibit reproducible bipolar resistance switching at higher bias voltages. The transition between both types of behaviour is observed by hysteresis in the I-V curves, indicating decomposition of the Ag(2)S, increasing the Ag(+) ion mobility. The as-fabricated Ag(2)S samples are a good candidate for future solid state memory devices, as they show reproducible memory resistive properties and they are fabricated by an accessible and reliable method.

Preparation and properties of electro-conductive fabrics based on polypyrrole: covalent vs. non-covalent attachment

NASA Astrophysics Data System (ADS)

David, N. C.; Anavi, D.; Milanovich, M.; Popowski, Y.; Frid, L.; Amir, E.

2017-10-01

Electro-conductive fabrics were prepared via in situ oxidative polymerization of pyrrole (Py) in the presence of unmodified and chemically modified cotton fabrics. Chemical modification of cotton fabric was achieved by covalent attachment of a bifunctional linker molecule to the surface of the fabric, followed by incorporation of a monomer unit onto the linker. The fabrics were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron spectroscopy, and thermal analysis. Furthermore, the effect of Py concentration on the degree of polypyrrole (PPy) grafting, surface morphology, electrical resistivity, and laundering durability were studied for both types of cotton fabrics. Reductions of several orders of magnitude in surface and volume electrical resistivities were observed for both non-covalently and covalently linked cotton-PPy systems, whereas the effect of covalent pre-treatment of the fabric was stronger at low Py concentration. On the other hand, at higher monomer concentration, the electrical properties and laundering durability of the fabrics we comparable for both unmodified and chemically pre-treated cotton fabrics, indicating that only a small fraction of PPy chains were chemically grafted onto the fabric surface with the majority of the polymer being connected to the fabric through hydrogen bonds.

Heat sealable, flame and abrasion resistant coated fabric. [clothing and containers for space exploration

NASA Technical Reports Server (NTRS)

Tschirch, R. P.; Sidman, K. R. (Inventor)

1981-01-01

Flame retardant, abrasion resistant elastomeric compositions are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Coated fabrics employing such elastomeric compositions as coating film are flexible, lightweight, and air impermeable and can be made using heat or dielectric sealing procedures.

Fabrication and evaluation of low fiber content alumina fiber/aluminum composites

NASA Technical Reports Server (NTRS)

Hack, J. E.; Strempek, G. C.

1980-01-01

The mechanical fabrication of low volume percent fiber, polycrystalline alumina fiber reinforced aluminum composites was accomplished. Wire preform material was prepared by liquid-metal infiltration of alumina fiber bundles. The wires were subsequently encapsulated with aluminum foil and fabricated into bulk composite material by hot-drawing. Extensive mechanical, thermal and chemical testing was conducted on preform and bulk material to develop a process and material data base. In addition, a preliminary investigation of mechanical forming of bulk alumina fiber reinforced aluminum composite material was conducted.

Low-cost and facile fabrication of a paper-based capillary electrophoresis microdevice for pathogen detection.

PubMed

Lee, Jee Won; Lee, Dohwan; Kim, Yong Tae; Lee, Eun Yeol; Kim, Do Hyun; Seo, Tae Seok

2017-05-15

This paper describes the development of a novel paper-based capillary electrophoresis (pCE) microdevice using mineral paper, which is durable, oil and tear resistant, and waterproof. The pCE device is inexpensive (~$1.6 per device for materials), simple to fabricate, lightweight, and disposable, so it is more adequate for point-of-care (POC) pathogen diagnostics than a conventional CE device made of glass, quartz, silicon or polymer. In addition, the entire fabrication process can be completed within 1h without using expensive clean room facilities and cumbersome photolithography procedures. A simple cross-designed pCE device was patterned on the mineral paper by using a plotter, and assembled with an OHP film via a double-sided adhesive film. After filling the microchannel with polyacrylamide gel, the injection, backbiasing, and separation steps were sequentially operated to differentiate single-stranded DNA (ssDNA) with 4 bp resolution in a 2.9cm-long CE separation channel. Furthermore, we successfully demonstrated the identification of the PCR amplicons of two target genes of Escherichia coli O157:H7 (rrsH gene, 121 bp) and Staphylococcus aureus (glnA gene, 225 bp). For accurate assignment of the peaks in the electropherogram, two bracket ladders (80 bp for the shortest and 326 bp for the longest) were employed, so the two amplicons of the pathogens were precisely identified on a pCE chip within 3min using the relative migration time ratio without effect of the CE environments. Thus, we believe that the pCE microdevice could be very useful for the separation of nucleic acids, amino acids, and ions as an analytical tool for use in the medical applications in the resource-limited environments as well as fundamental research fields. Copyright © 2016 Elsevier B.V. All rights reserved.

Properties of honeycomb polyester knitted fabrics

NASA Astrophysics Data System (ADS)

Feng, A. F.

2016-07-01

The properties of honeycomb polyester weft-knitted fabrics were studied to understand their advantages. Seven honeycomb polyester weft-knitted fabrics and one common polyester weft-knitted fabric were selected for testing. Their bursting strengths, fuzzing and pilling, air permeability, abrasion resistance and moisture absorption and perspiration were studied. The results show that the honeycomb polyester weft-knitted fabrics have excellent moisture absorption and liberation. The smaller their thicknesses and area densities are, the better their moisture absorption and liberation will be. Their anti-fuzzing and anti-pilling is good, whereas their bursting strengths and abrasion resistance are poorer compared with common polyester fabric's. In order to improve the hygroscopic properties of the fabrics, the proportion of the honeycomb microporous structure modified polyester in the fabrics should not be less than 40%.

Campanile Near-Field Probes Fabricated by Nanoimprint Lithography on the Facet of an Optical Fiber

DOE PAGES

Calafiore, Giuseppe; Koshelev, Alexander; Darlington, Thomas P.; ...

2017-05-10

One of the major challenges to the widespread adoption of plasmonic and nano-optical devices in real-life applications is the difficulty to mass-fabricate nano-optical antennas in parallel and reproducible fashion, and the capability to precisely place nanoantennas into devices with nanometer-scale precision. In this study, we present a solution to this challenge using the state-of-the-art ultraviolet nanoimprint lithography (UV-NIL) to fabricate functional optical transformers onto the core of an optical fiber in a single step, mimicking the 'campanile' near-field probes. Imprinted probes were fabricated using a custom-built imprinter tool with co-axial alignment capability with sub < 100 nm position accuracy, followedmore » by a metallization step. Scanning electron micrographs confirm high imprint fidelity and precision with a thin residual layer to facilitate efficient optical coupling between the fiber and the imprinted optical transformer. The imprinted optical transformer probe was used in an actual NSOM measurement performing hyperspectral photoluminescence mapping of standard fluorescent beads. The calibration scans confirmed that imprinted probes enable sub-diffraction limited imaging with a spatial resolution consistent with the gap size. This novel nano-fabrication approach promises a low-cost, high-throughput, and reproducible manufacturing of advanced nano-optical devices.« less

Campanile Near-Field Probes Fabricated by Nanoimprint Lithography on the Facet of an Optical Fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calafiore, Giuseppe; Koshelev, Alexander; Darlington, Thomas P.

One of the major challenges to the widespread adoption of plasmonic and nano-optical devices in real-life applications is the difficulty to mass-fabricate nano-optical antennas in parallel and reproducible fashion, and the capability to precisely place nanoantennas into devices with nanometer-scale precision. In this study, we present a solution to this challenge using the state-of-the-art ultraviolet nanoimprint lithography (UV-NIL) to fabricate functional optical transformers onto the core of an optical fiber in a single step, mimicking the 'campanile' near-field probes. Imprinted probes were fabricated using a custom-built imprinter tool with co-axial alignment capability with sub < 100 nm position accuracy, followedmore » by a metallization step. Scanning electron micrographs confirm high imprint fidelity and precision with a thin residual layer to facilitate efficient optical coupling between the fiber and the imprinted optical transformer. The imprinted optical transformer probe was used in an actual NSOM measurement performing hyperspectral photoluminescence mapping of standard fluorescent beads. The calibration scans confirmed that imprinted probes enable sub-diffraction limited imaging with a spatial resolution consistent with the gap size. This novel nano-fabrication approach promises a low-cost, high-throughput, and reproducible manufacturing of advanced nano-optical devices.« less

Low resistance Ohmic contact to p-type crystalline silicon via nitrogen-doped copper oxide films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xinyu, E-mail: xinyu.zhang@anu.edu.au; Wan, Yimao; Bullock, James

2016-08-01

This work explores the application of transparent nitrogen doped copper oxide (CuO{sub x}:N) films deposited by reactive sputtering to create hole-selective contacts for p-type crystalline silicon (c-Si) solar cells. It is found that CuO{sub x}:N sputtered directly onto crystalline silicon is able to form an Ohmic contact. X-ray photoelectron spectroscopy and Raman spectroscopy measurements are used to characterise the structural and physical properties of the CuO{sub x}:N films. Both the oxygen flow rate and the substrate temperature during deposition have a significant impact on the film composition, as well as on the resulting contact resistivity. After optimization, a low contactmore » resistivity of ∼10 mΩ cm{sup 2} has been established. This result offers significant advantages over conventional contact structures in terms of carrier transport and device fabrication.« less

Low-voltage, large-strain soft electrothermal actuators based on laser-reduced graphene oxide/Ag particle composites

NASA Astrophysics Data System (ADS)

Wang, Qian; Li, Yu-Tao; Zhang, Tian-Yu; Wang, Dan-Yang; Tian, Ye; Yan, Jun-Chao; Tian, He; Yang, Yi; Yang, Fan; Ren, Tian-Ling

2018-03-01

In this paper, low-voltage, large-strain flexible electrothermal actuators (ETAs) based on laser-reduced graphene oxide (LRGO)/Ag particle composites were fabricated in a simple and cost-efficient process. By adding Ag particles to the LRGO, the sheet resistance decreased effectively. Under a driving voltage of 28 V, the actuator obtained a bending angle of 192° within 6 s. Besides, the bending deformation could be precisely controlled by the driving voltage ranging from 10° to 192°. Finally, a gripper composed of two actuators was demonstrated to manipulate a piece of polydimethylsiloxane block. With the advantages of low-voltage, fast-response, and easy-to-manufacture, the graphene based ETAs have a promising application in soft robotics and soft machines.

Development of components for IFOG-based inertial measurement units using polymer waveguide fabrication technologies

NASA Astrophysics Data System (ADS)

Ashley, P. R.; Temmen, M. G.; Diffey, W. M.; Sanghadasa, M.; Bramson, M. D.

2007-10-01

Active and passive polymer materials have been successfully used in the development of highly accurate, compact and low cost guided-wave components: an optical transceiver and a phase modulator, for inertial measurement units (IMUs) based on the interferometric fibre optic gyroscope (IFOG) technology for precision guidance in navigation systems. High performance and low noise transceivers with high optical power and good spectral quality were fabricated using a silicon-bench architecture. Low loss phase modulators with low halfwave drive voltage (Vπ) have been fabricated with a backscatter compensated design using polarizing waveguides consisting of CLD- and FTC-type high performance electro-optic (E-O) chromophores. Gyro bias stability of less than 0.02° h-1 has been demonstrated with these guided-wave components.

Fabrication of micromachined ceramic thin-film-type pressure sensors for overpressure tolerance and its characteristics

NASA Astrophysics Data System (ADS)

Chung, Gwiy-Sang; Kim, Jae-Min

2004-04-01

This paper describes the fabrication process and characteristics of ceramic thin-film pressure sensors based on Ta-N strain gauges for harsh environment applications. The Ta-N thin-film strain gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragm with buried cavities for overpressure tolerance. The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relatively higher resistance, stability and gauge factor of Ta-N thin-films more than other gauges. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low nonlinearity and excellent temperature stability. The sensitivity is 1.21-1.097 mV/V×kgf/cm2 in temperature ranges of 25-200°C and a maximum non-linearity is 0.43 %FS.

Rinse-resistant superhydrophobic block copolymer fabrics by electrospinning, electrospraying and thermally-induced self-assembly

NASA Astrophysics Data System (ADS)

Wu, Jie; Li, Xin; Wu, Yang; Liao, Guoxing; Johnston, Priscilla; Topham, Paul D.; Wang, Linge

2017-11-01

An inherent problem that restricts the practical application of superhydrophobic materials is that the superhydrophobic property is not sustainable; it can be diminished, or even lost, when the surface is physically damaged. In this work, we present an efficient approach for the fabrication of superhydrophobic fibrous fabrics with great rinse-resistance where a block copolymer has been electrospun into a nanofibrous mesh while micro-sized beads have been subsequently electrosprayed to give a morphologically composite material. The intricate nano- and microstructure of the composite was then fixed by thermally annealing the block copolymer to induce self-assembly and interdigitation of the microphase separated domains. To demonstrate this approach, a polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) nanofibrous scaffold was produced by electrospinning before SEBS beads were electrosprayed into this mesh to form a hierarchical micro/nanostructure of beads and fibers. The effects of type and density of SEBS beads on the surface morphology and wetting properties of composite membranes were studied extensively. Compared with a neat SEBS fibrous mesh, the composite membrane had enhanced hydrophobic properties. The static water contact angle increased from 139° (±3°) to 156° (±1°), while the sliding angle decreased to 8° (±1°) from nearly 90°. In order to increase the rinse-resistance of the composite membrane, a thermal annealing step was applied to physically bind the fibers and beads. Importantly, after 200 h of water flushing, the hierarchical surface structure and superhydrophobicity of the composite membrane were well retained. This work provides a new route for the creation of superhydrophobic fabrics with potential in self-cleaning applications.

Robust and durable superhydrophobic fabrics fabricated via simple Cu nanoparticles deposition route and its application in oil/water separation.

PubMed

Wang, Jintao; Wang, Hongfei

2017-06-15

The exploitation of separation materials with high selectivity for oil pollutants is of great importance due to severe environmental damage from oil spillages and industrial discharge of oils. A facile in situ growth process for creating superhydrophobic-superoleophilic fabrics for oil-water separation is developed. This proposed method is based mainly on the deposition Cu nanoparticles and subsequent hydrophobic modification. Compared with the hydrophilicity of original fabric, the water contact angle of the modified fabric rises to 154.5°, suggesting its superhydrophobicity. The as-prepared fabrics also exhibit wonderful oil-water selectivity, excellent recyclability, and high separation efficiency (>94.5%). Especially, via pumping the fabric rolled into a multilayered tube, various types of oils on water surface can be continuously separated in situ without any water uptake. Furthermore, the superhydrophobic fabrics show excellent superhydrophobic stability, and can resist different chemicals, such as salty, acidic, and alkaline solutions, oils, and hot water. After the abrasion of 400cycles, the broken fabric still possesses highly hydrophobicity with water contact angle of 145°. Therefore, due to simple fabrication steps, low cost, and scalable process, the as-prepared fabrics can be applied in the separation of oils and other organic solvents from water. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reliable fabrication of plasmonic nanostructures without an adhesion layer using dry lift-off

NASA Astrophysics Data System (ADS)

Chen, Yiqin; Li, Zhiqin; Xiang, Quan; Wang, Yasi; Zhang, Zhiqiang; Duan, Huigao

2015-10-01

Lift-off is the most commonly used pattern-transfer method to define lithographic plasmonic metal nanostructures. A typical lift-off process is realized by dissolving patterned resists in solutions, which has the limits of low yield when not using adhesion layers and incompatibility with the fabrication of some specific structures and devices. In this work, we report an alternative ‘dry’ lift-off process to obtain metallic nanostructures via mechanical stripping by using the advantage of poor adhesion between resists and noble metal films. We show that this dry stripping lift-off method is effective for both positive- and negative-tone resists to fabricate sparse and densely-packed plasmonic nanostructures, respectively. In particular, this method is achieved without using an adhesion layer, which enables the mitigation of plasmon damping to obtain larger field enhancement. Dark-field scattering, one-photon luminescence and surface-enhanced Raman scattering measurements were performed to demonstrate the improved quality factor of the plasmonic nanostructures fabricated by this dry lift-off process.

NCI and the Precision Medicine Initiative®

Cancer.gov

NCI's activities related to precision medicine focuses on new and expanded precision medicine clinical trials; mechanisms to overcome drug resistance to cancer treatments; and developing a shared digital repository of precision medicine trials data.

‘Chip-olate’ and dry-film resists for efficient fabrication, singulation and sealing of microfluidic chips

NASA Astrophysics Data System (ADS)

Temiz, Yuksel; Delamarche, Emmanuel

2014-09-01

This paper describes a technique for high-throughput fabrication and efficient singulation of chips having closed microfluidic structures and takes advantage of dry-film resists (DFRs) for efficient sealing of capillary systems. The technique is illustrated using 4-inch Si/SiO2 wafers. Wafers carrying open microfluidic structures are partially diced to about half of their thickness. Treatments such as surface cleaning are done at wafer-level, then the structures are sealed using low-temperature (45 °C) lamination of a DFR that is pre-patterned using a craft cutter, and ready-to-use chips are finally separated manually like a chocolate bar by applying a small force (≤ 4 N). We further show that some DFRs have low auto-fluorescence at wavelengths typically used for common fluorescent dyes and that mechanical properties of some DFRs allow for the lamination of 200 μm wide microfluidic structures with negligible sagging (~1 μm). The hydrophilicity (advancing contact angle of ~60°) of the DFR supports autonomous capillary-driven flow without the need for additional surface treatment of the microfluidic chips. Flow rates from 1 to 5 µL min-1 are generated using different geometries of channels and capillary pumps. In addition, the ‘chip-olate’ technique is compatible with the patterning of capture antibodies on DFR for use in immunoassays. We believe this technique to be applicable to the fabrication of a wide range of microfluidic and lab-on-a-chip devices and to offer a viable alternative to many labor-intensive processes that are currently based on wafer bonding techniques or on the molding of poly(dimethylsiloxane) (PDMS) layers.

Design and Fabrication of a Precision Template for Spine Surgery Using Selective Laser Melting (SLM)

PubMed Central

Wang, Di; Wang, Yimeng; Wang, Jianhua; Song, Changhui; Yang, Yongqiang; Zhang, Zimian; Lin, Hui; Zhen, Yongqiang; Liao, Suixiang

2016-01-01

In order to meet the clinical requirements of spine surgery, this paper proposes the fabrication of the customized template for spine surgery through computer-aided design. A 3D metal printing-selective laser melting (SLM) technique was employed to directly fabricate the 316L stainless steel template, and the metal template with tiny locating holes was used as an auxiliary tool to insert spinal screws inside the patient’s body. To guarantee accurate fabrication of the template for cervical vertebra operation, the contact face was placed upwards to improve the joint quality between the template and the cervical vertebra. The joint surface of the printed template had a roughness of Ra = 13 ± 2 μm. After abrasive blasting, the surface roughness was Ra = 7 ± 0.5 μm. The surgical metal template was bound with the 3D-printed Acrylonitrile Butadiene Styrene (ABS) plastic model. The micro-hardness values determined at the cross-sections of SLM-processed samples varied from HV0.3 250 to HV0.3 280, and the measured tensile strength was in the range of 450 MPa to 560 MPa, which showed that the template had requisite strength. Finally, the metal template was clinically used in the patient’s surgical operation, and the screws were inserted precisely as the result of using the auxiliary template. The geometrical parameters of the template hole (e.g., diameter and wall thickness) were optimized, and measures were taken to optimize the key geometrical units (e.g., hole units) in metal 3D printing. Compared to the traditional technology of screw insertion, the use of the surgical metal template enabled the screws to be inserted more easily and accurately during spinal surgery. However, the design of the high-quality template should fully take into account the clinical demands of surgeons, as well as the advice of the designing engineers and operating technicians. PMID:28773730

Precision Fit of Screw-Retained Implant-Supported Fixed Dental Prostheses Fabricated by CAD/CAM, Copy-Milling, and Conventional Methods.

PubMed

de França, Danilo Gonzaga; Morais, Maria Helena; das Neves, Flávio D; Carreiro, Adriana Fonte; Barbosa, Gustavo As

The aim of this study was to evaluate the effectiveness of fabrication methods (computer-aided design/computer-aided manufacture [CAD/CAM], copy-milling, and conventional casting) in the fit accuracy of three-unit, screw-retained fixed dental prostheses. Sixteen three-unit implant-supported screw-retained frameworks were fabricated to fit an in vitro model. Eight frameworks were fabricated using the CAD/CAM system, four in zirconia and four in cobalt-chromium. Four zirconia frameworks were fabricated using the copy-milled system, and four were cast in cobalt-chromium using conventional casting with premachined abutments. The vertical and horizontal misfit at the implant-framework interface was measured using scanning electron microscopy at ×250. The results for vertical misfit were analyzed using Kruskal-Wallis and Mann-Whitney tests. The horizontal misfits were categorized as underextended, equally extended, or overextended. Statistical analysis established differences between groups according to the chi-square test (α = .05). The mean vertical misfit was 5.9 ± 3.6 μm for CAD/CAM-fabricated zirconia, 1.2 ± 2.2 μm for CAD/CAM-fabricated cobalt-chromium frameworks, 7.6 ± 9.2 μm for copy-milling-fabricated zirconia frameworks, and 11.8 (9.8) μm for conventionally fabricated frameworks. The Mann-Whitney test revealed significant differences between all but the zirconia-fabricated frameworks. A significant association was observed between the horizontal misfits and the fabrication method. The percentage of horizontal misfits that were underextended and overextended was higher in milled zirconia (83.3%), CAD/CAM cobaltchromium (66.7%), cast cobalt-chromium (58.3%), and CAD/CAM zirconia (33.3%) frameworks. CAD/CAM-fabricated frameworks exhibit better vertical misfit and low variability compared with copy-milled and conventionally fabricated frameworks. The percentage of interfaces equally extended was higher when CAD/CAM and zirconia were used.

Low temperature dissolution creep induced B-type olivine fabric during serpentinization and deformation in mantle wedge

NASA Astrophysics Data System (ADS)

Liu, W.; Zhang, J.

2017-12-01

The B-type olivine fabric (i.e., the [010]ol axes subnormal to foliation and the [001]ol axes subparallel to the lineation) has been regarded as an important olivine fabric for interpreting global trench-parallel S-wave polarization in fore-arc regions. However, strong serpentinization and cold temperature environment in the mantle wedge should inhibit development of the B-type olivine fabric that requires high temperature to activate solid-state plastic deformation. Here we report fabrics of olivine and antigorite generated at low temperatures (300-370 oC) during serpentinization in a fossil mantle wedge of the Val Malenco area, Central Alps. Olivine in the serpentine matrix develops a pronounced B-type fabric, while antigorite in the same matrix displays a strong crystallographic orientation (CPO) with the (001) and the [010] subparallel to foliation and lineation, respectively. The following evidence leads to the conclusion that the B-type olivine fabric is resulted from dissolution creep assisted by grain boundaries sliding (GBS) and grain rotation, rather than solid-state plastic deformation: (1) serpentinization took place at low temperatures and a fluid-enriched environment, ideal for dissolution-precipitation creep; (2) the voids and zigzag boundaries along the interface between antigorite and olivine suggest a fluid dissolution reaction; (3) the primary coarse olivine develops a nearly random fabric, indicating the B-type fabrics in the fine-grained olivine can't be inherited fabrics. These results document for the first time the B-type olivine CPO formed by dissolution creep at low temperatures during serpentinization and provide a mechanism to reconcile petrofabric observations with geophysical observations of trench parallel fast S-wave seismic anisotropy in fore-arc mantle wedge regions.

Fabrication, characterization, and modeling of comixed films for NXS calibration targets [Fabrication and metrology of the NXS calibration targets

DOE PAGES

Jaquez, Javier; Farrell, Mike; Huang, Haibo; ...

2016-08-01

In 2014/2015 at the Omega laser facility, several experiments took place to calibrate the National Ignition Facility (NIF) X-ray spectrometer (NXS), which is used for high-resolution time-resolved spectroscopic experiments at NIF. The spectrometer allows experimentalists to measure the X-ray energy emitted from high-energy targets, which is used to understand key data such as mixing of materials in highly compressed fuel. The purpose of the experiments at Omega was to obtain information on the instrument performance and to deliver an absolute photometric calibration of the NXS before it was deployed at NIF. The X-ray emission sources fabricated for instrument calibration weremore » 1-mm fused silica spheres with precisely known alloy composition coatings of Si/Ag/Mo, Ti/Cr/Ag, Cr/Ni/Zn, and Zn/Zr, which have emission in the 2- to 18-keV range. Critical to the spectrometer calibration is a known atomic composition of elements with low uncertainty for each calibration sphere. This study discusses the setup, fabrication, and precision metrology of these spheres as well as some interesting findings on the ternary magnetron-sputtered alloy structure.« less

Fabrication, characterization, and modeling of comixed films for NXS calibration targets [Fabrication and metrology of the NXS calibration targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaquez, Javier; Farrell, Mike; Huang, Haibo

In 2014/2015 at the Omega laser facility, several experiments took place to calibrate the National Ignition Facility (NIF) X-ray spectrometer (NXS), which is used for high-resolution time-resolved spectroscopic experiments at NIF. The spectrometer allows experimentalists to measure the X-ray energy emitted from high-energy targets, which is used to understand key data such as mixing of materials in highly compressed fuel. The purpose of the experiments at Omega was to obtain information on the instrument performance and to deliver an absolute photometric calibration of the NXS before it was deployed at NIF. The X-ray emission sources fabricated for instrument calibration weremore » 1-mm fused silica spheres with precisely known alloy composition coatings of Si/Ag/Mo, Ti/Cr/Ag, Cr/Ni/Zn, and Zn/Zr, which have emission in the 2- to 18-keV range. Critical to the spectrometer calibration is a known atomic composition of elements with low uncertainty for each calibration sphere. This study discusses the setup, fabrication, and precision metrology of these spheres as well as some interesting findings on the ternary magnetron-sputtered alloy structure.« less

Atomically Precise Surface Engineering for Producing Imagers

NASA Technical Reports Server (NTRS)

Nikzad, Shouleh (Inventor); Hoenk, Michael E. (Inventor); Greer, Frank (Inventor); Jones, Todd J. (Inventor)

2015-01-01

High-quality surface coatings, and techniques combining the atomic precision of molecular beam epitaxy and atomic layer deposition, to fabricate such high-quality surface coatings are provided. The coatings made in accordance with the techniques set forth by the invention are shown to be capable of forming silicon CCD detectors that demonstrate world record detector quantum efficiency (>50%) in the near and far ultraviolet (155 nm-300 nm). The surface engineering approaches used demonstrate the robustness of detector performance that is obtained by achieving atomic level precision at all steps in the coating fabrication process. As proof of concept, the characterization, materials, and exemplary devices produced are presented along with a comparison to other approaches.

Low-cost and large-scale flexible SERS-cotton fabric as a wipe substrate for surface trace analysis

NASA Astrophysics Data System (ADS)

Chen, Yanmin; Ge, Fengyan; Guang, Shanyi; Cai, Zaisheng

2018-04-01

The large-scale surface enhanced Raman scattering (SERS) cotton fabrics were fabricated based on traditional woven ones using a dyeing-like method of vat dyes, where silver nanoparticles (Ag NPs) were in-situ synthesized by 'dipping-reducing-drying' process. By controlling the concentration of AgNO3 solution, the optimal SERS cotton fabric was obtained, which had a homogeneous close packing of Ag NPs. The SERS cotton fabric was employed to detect p-Aminothiophenol (PATP). It was found that the new fabric possessed excellent reproducibility (about 20%), long-term stability (about 57 days) and high SERS sensitivity with a detected concentration as low as 10-12 M. Furthermore, owing to the excellent mechanical flexibility and good absorption ability, the SERS cotton fabric was employed to detect carbaryl on the surface of an apple by simply swabbing, which showed great potential in fast trace analysis. More importantly, this study may realize large-scale production with low cost by a traditional cotton fabric.

Multifunctional surface modification of silk fabric via graphene oxide repeatedly coating and chemical reduction method

NASA Astrophysics Data System (ADS)

Cao, Jiliang; Wang, Chaoxia

2017-05-01

Multifunctional silk fabrics with electrical conductive, anti-ultraviolet and water repellent were successfully prepared by surface modification with graphene oxide (GO). The yellow-brown GO deposited on the surface of silk fabric was converted into graphitic black reduced graphene (RGO) by sodium hydrosulfite. The surface properties of silk fabrics were changed by repeatedly RGO coating process, which have been proved by SEM and XPS. The SEM results showed that the RGO sheets were successive form a continuously thin film on the surface of silk fabrics, and the deposition of GO or RGO also can be proved by XPS. The electrical conductivity was tested by electrical surface resistance value of the silk fabric, the surface resistance decreased with increasing of RGO surface modification times, and a low surface resistance value reached to 3.24 KΩ cm-1 after 9 times of modification, indicating the silk obtained excellent conductivity. The UPF value of one time GO modification silk fabric (silk-1RGO) was enhanced significantly to 24.45 in comparison to 10.40 of original silk. The contact angle of RGO coating silk samples was all above of 120°. The durability of RGO coated silk fabrics was tested by laundering. The electrical surface resistance of silk-4RGO (65.74 KΩ cm-1), silk-6RGO (15.54 KΩ cm-1) and silk-8RGO (3.86 KΩ cm-1) fabrics was up to 86.82, 22.30 and 6.57 KΩ cm-1 after 10 times of standard washing, respectively. The UPF value, contact angle and color differences of RGO modified silk fabric slightly changed before and after 10 times of standard washing. Therefore, the washing fastness of electric conduction, anti-ultraviolet and water repellent multifunctional silk fabrics was excellent.

Low-Thermal-Resistance Baseplate Mounting

NASA Technical Reports Server (NTRS)

Perreault, W. T.

1984-01-01

Low-thermal-resistance mounting achieved by preloading baseplate to slight convexity with screws threaded through beam. As mounting bolts around edge of base-place tightened, baseplate and cold plate contact first in center, with region of intimate contact spreading outward as bolts tightened.

Capacitors with low equivalent series resistance

NASA Technical Reports Server (NTRS)

Lakeman, Charles D. E. (Inventor); Fuge, Mark (Inventor); Fleig, Patrick Franz (Inventor)

2011-01-01

An electric double layer capacitor (EDLC) in a coin or button cell configuration having low equivalent series resistance (ESR). The capacitor comprises mesh or other porous metal that is attached via conducting adhesive to one or both the current collectors. The mesh is embedded into the surface of the adjacent electrode, thereby reducing the interfacial resistance between the electrode and the current collector, thus reducing the ESR of the capacitor.

Nature-Inspired Strategy toward Superhydrophobic Fabrics for Versatile Oil/Water Separation.

PubMed

Zhou, Cailong; Chen, Zhaodan; Yang, Hao; Hou, Kun; Zeng, Xinjuan; Zheng, Yanfen; Cheng, Jiang

2017-03-15

Phytic acid, which is a naturally occurring component that is widely found in many plants, can strongly bond toxic mineral elements in the human body, because of its six phosphate groups. Some of the metal ions present the property of bonding with phytic acid to form insoluble coordination complexes aggregations, even at room temperature. Herein, a superhydrophobic cotton fabric was prepared using a novel and facile nature-inspired strategy that introduced phytic acid metal complex aggregations to generate rough hierarchical structures on a fabric surface, followed by PDMS modification. This superhydrophobic surface can be constructed not only on cotton fabric, but also on filter paper, polyethylene terephthalate (PET) fabric, and sponge. Ag I , Fe III , Ce III , Zr IV , and Sn IV are very commendatory ions in our study. Taking phytic acid-Fe III -based superhydrophobic fabric as an example, it showed excellent resistance to ultraviolet (UV) irradiation, high temperature, and organic solvent immersion, and it has good resistance to mechanical wear and abrasion. The superhydrophobic/superoleophilic fabric was successfully used to separate oil/water mixtures with separation efficiencies as high as 99.5%. We envision that these superantiwetting fabrics, modified with phytic acid-metal complexes and PDMS, are environmentally friendly, low cost, sustainable, and easy to scale up, and thereby exhibit great potentials in practical applications.

Precision medicine driven by cancer systems biology.

PubMed

Filipp, Fabian V

2017-03-01

Molecular insights from genome and systems biology are influencing how cancer is diagnosed and treated. We critically evaluate big data challenges in precision medicine. The melanoma research community has identified distinct subtypes involving chronic sun-induced damage and the mitogen-activated protein kinase driver pathway. In addition, despite low mutation burden, non-genomic mitogen-activated protein kinase melanoma drivers are found in membrane receptors, metabolism, or epigenetic signaling with the ability to bypass central mitogen-activated protein kinase molecules and activating a similar program of mitogenic effectors. Mutation hotspots, structural modeling, UV signature, and genomic as well as non-genomic mechanisms of disease initiation and progression are taken into consideration to identify resistance mutations and novel drug targets. A comprehensive precision medicine profile of a malignant melanoma patient illustrates future rational drug targeting strategies. Network analysis emphasizes an important role of epigenetic and metabolic master regulators in oncogenesis. Co-occurrence of driver mutations in signaling, metabolic, and epigenetic factors highlights how cumulative alterations of our genomes and epigenomes progressively lead to uncontrolled cell proliferation. Precision insights have the ability to identify independent molecular pathways suitable for drug targeting. Synergistic treatment combinations of orthogonal modalities including immunotherapy, mitogen-activated protein kinase inhibitors, epigenetic inhibitors, and metabolic inhibitors have the potential to overcome immune evasion, side effects, and drug resistance.

Development of a low-cost mini environment chamber for precision instruments

NASA Astrophysics Data System (ADS)

Feng, Jian; Li, Rui-Jun; He, Ya-Xiong; Fan, Kuang-Chao

2016-01-01

The wavelength of laser interferometer used widely in precision measurement instrument is affected by the refractive index of surrounding air, which depends on the temperature, relative humidity (RH) and air pressure. A low-cost mini chamber based on the natural convection principle with high-precision temperature-controlled and humidity-suppressed is proposed in this paper. The main chamber is built up by acrylic walls supported by aluminum beam column and are tailored according to the required space. A thin layer of vacuum insulation panel (VIP) with an ultralow thermal conductivity coefficient is adhered around the walls so as to prevent heat exchange with room air. A high-precision temperature sensor measuring the temperature near the instrument's measuring point provides a feedback signal to a proportional-integral-derivative (PID) controller. Several thermoelectric coolers uniformly arranged on the ceiling of the chamber to cool the air inside the chamber directly without any air supply system, yielding a vibration-free cooling system. A programmable power supply is used as the driver for the coolers to generate different cooling capacities. The down-flowing cool air and the up-flowing hot air form a natural convection, and the air temperature in the chamber gradually becomes stable and finally reaches the temperature set by the PID controller. Recycled desiccant contained silica gels that have high affinity for water is used as a drying agent. Experimental results show that in about two hours the system's steady state error is 0.003°C on average, and the variation range is less than ± 0.02°C when the set temperature is 20°C, the RH is reduced from 66% to about 48%. This innovative mini chamber has the advantages of low-cost, vibration-free, and low energy-consumption. It can be used for any micro/nanomeasurement instrument and its volume can be customer-designed.

Low-loss optical waveguides in β-BBO crystal fabricated by femtosecond-laser writing

NASA Astrophysics Data System (ADS)

Li, Ziqi; Cheng, Chen; Romero, Carolina; Lu, Qingming; Vázquez de Aldana, Javier Rodríguez; Chen, Feng

2017-11-01

We report on the fabrication and characterization of β-BBO depressed cladding waveguides fabricated by femtosecond-laser writing with no significant changes in the waveguide lattice microstructure. The waveguiding properties and the propagation losses of the cladding structures are investigated, showing good transmission properties at wavelengths of 400 and 800 nm along TM polarization. The minimum propagation losses are measured to be as low as 0.19 dB/cm at wavelength of 800 nm. The well-preserved waveguide lattice microstructure and good guiding performances with low propagation losses suggest the potential applications of the cladding waveguides in β-BBO crystal as novel integrated photonic devices.

Microbiopsy/precision cutting devices

DOEpatents

Krulevitch, Peter A.; Lee, Abraham P.; Northrup, M. Allen; Benett, William J.

1999-01-01

Devices for performing tissue biopsy on a small scale (microbiopsy). By reducing the size of the biopsy tool and removing only a small amount of tissue or other material in a minimally invasive manner, the risks, costs, injury and patient discomfort associated with traditional biopsy procedures can be reduced. By using micromachining and precision machining capabilities, it is possible to fabricate small biopsy/cutting devices from silicon. These devices can be used in one of four ways 1) intravascularly, 2) extravascularly, 3) by vessel puncture, and 4) externally. Additionally, the devices may be used in precision surgical cutting.

Microbiopsy/precision cutting devices

DOEpatents

Krulevitch, P.A.; Lee, A.P.; Northrup, M.A.; Benett, W.J.

1999-07-27

Devices are disclosed for performing tissue biopsy on a small scale (microbiopsy). By reducing the size of the biopsy tool and removing only a small amount of tissue or other material in a minimally invasive manner, the risks, costs, injury and patient discomfort associated with traditional biopsy procedures can be reduced. By using micromachining and precision machining capabilities, it is possible to fabricate small biopsy/cutting devices from silicon. These devices can be used in one of four ways (1) intravascularly, (2) extravascularly, (3) by vessel puncture, and (4) externally. Additionally, the devices may be used in precision surgical cutting. 6 figs.

Nonvacuum, maskless fabrication of a flexible metal grid transparent conductor by low-temperature selective laser sintering of nanoparticle ink.

PubMed

Hong, Sukjoon; Yeo, Junyeob; Kim, Gunho; Kim, Dongkyu; Lee, Habeom; Kwon, Jinhyeong; Lee, Hyungman; Lee, Phillip; Ko, Seung Hwan

2013-06-25

We introduce a facile approach to fabricate a metallic grid transparent conductor on a flexible substrate using selective laser sintering of metal nanoparticle ink. The metallic grid transparent conductors with high transmittance (>85%) and low sheet resistance (30 Ω/sq) are readily produced on glass and polymer substrates at large scale without any vacuum or high-temperature environment. Being a maskless direct writing method, the shape and the parameters of the grid can be easily changed by CAD data. The resultant metallic grid also showed a superior stability in terms of adhesion and bending. This transparent conductor is further applied to the touch screen panel, and it is confirmed that the final device operates firmly under continuous mechanical stress.

Low-Resistivity Zinc Selenide for Heterojunctions

NASA Technical Reports Server (NTRS)

Stirn, R. J.

1986-01-01

Magnetron reactive sputtering enables doping of this semiconductor. Proposed method of reactive sputtering combined with doping shows potential for yielding low-resistivity zinc selenide films. Zinc selenide attractive material for forming heterojunctions with other semiconductor compounds as zinc phosphide, cadmium telluride, and gallium arsenide. Semiconductor junctions promising for future optoelectronic devices, including solar cells and electroluminescent displays. Resistivities of zinc selenide layers deposited by evaporation or chemical vapor deposition too high to form practical heterojunctions.

Micromachining of silicon carbide on silicon fabricated by low-pressure chemical vapour deposition

NASA Astrophysics Data System (ADS)

Behrens, Ingo; Peiner, Erwin; Bakin, Andrey S.; Schlachetzki, Andreas

2002-07-01

We describe the fabrication of silicon carbide layers for micromechanical applications using low-pressure metal-organic chemical vapour deposition at temperatures below 1000 °C. The layers can be structured by lift-off using silicon dioxide as a sacrificial layer. A large selectivity with respect to silicon can be exploited for bulk micromachining. Thin membranes are fabricated which exhibit high mechanical quality, as necessary for applications in harsh environments.

Mechanical properties and cell-culture characteristics of a polycaprolactone kagome-structure scaffold fabricated by a precision extruding deposition system.

PubMed

Lee, Se-Hwan; Cho, Yong Sang; Hong, Myoung Wha; Lee, Bu-Kyu; Park, Yongdoo; Park, Sang-Hyug; Kim, Young Yul; Cho, Young-Sam

2017-09-13

To enhance the mechanical properties of three-dimensional (3D) scaffolds used for bone regeneration in tissue engineering, many researchers have studied their structure and chemistry. In the structural engineering field, the kagome structure has been known to have an excellent relative strength. In this study, to enhance the mechanical properties of a synthetic polymer scaffold used for tissue engineering, we applied the 3D kagome structure to a porous scaffold for bone regeneration. Prior to fabricating the biocompatible-polymer scaffold, the ideal kagome structure, which was manufactured by a 3D printer of the digital light processing type, was compared with a grid-structure, which was used as the control group, using a compressive experiment. A polycaprolactone (PCL) kagome-structure scaffold was successfully fabricated by additive manufacturing using a 3D printer with a precision extruding deposition head. To assess the physical characteristics of the fabricated PCL-kagome-structure scaffold, we analyzed its porosity, pore size, morphological structure, surface roughness, compressive stiffness, and mechanical bending properties. The results showed that, the mechanical properties of proposed kagome-structure scaffold were superior to those of a grid-structure scaffold. Moreover, Sarcoma osteogenic (Saos-2) cells were used to evaluate the characteristics of in vitro cell proliferation. We carried out cell counting kit-8 (CCK-8) and DNA contents assays. Consequently, the cell proliferation of the kagome-structure scaffold was increased; this could be because the surface roughness of the kagome-structure scaffold enhances initial cell attachment.

A versatile technique for fabrication of SiC SPM probes

NASA Astrophysics Data System (ADS)

Therrien, Joel; Schmidt, Daniel; Barrot, Sheetal; Patel, Bhavin

2008-03-01

To date SPM probes have largely been fabricated via methods borrowed from the semiconductor industry for fabricating Micro Electro Mechanical Systems. Although these techniques have enabled SPM to see widespread use, the processes put significant limitations on what structures can be made. We report our progress on fabricating SPM cantilevers composed of Silicon Carbide using polymer molding techniques. A pre-ceramic polymer is molded into the desired probe shape and then converted to SiC via pyrolisys. We will also report on progress in using photo-sterolithography for fabrication of even more complex geometries. In addition to opening up a much larger set of probe structures, the use of SiC leads to improved wear resistance of the resulting probes. Among the potential applications, this method enables the fabrication of low spring constant, high resonant frequency cantilevers via cross sectional geometries not accessible to standard fabrication techniques. Such probes are required for high speed tapping and non-contact imaging.

High-Performance Flexible Transparent Electrode with an Embedded Metal Mesh Fabricated by Cost-Effective Solution Process.

PubMed

Khan, Arshad; Lee, Sangeon; Jang, Taehee; Xiong, Ze; Zhang, Cuiping; Tang, Jinyao; Guo, L Jay; Li, Wen-Di

2016-06-01

A new structure of flexible transparent electrodes is reported, featuring a metal mesh fully embedded and mechanically anchored in a flexible substrate, and a cost-effective solution-based fabrication strategy for this new transparent electrode. The embedded nature of the metal-mesh electrodes provides a series of advantages, including surface smoothness that is crucial for device fabrication, mechanical stability under high bending stress, strong adhesion to the substrate with excellent flexibility, and favorable resistance against moisture, oxygen, and chemicals. The novel fabrication process replaces vacuum-based metal deposition with an electrodeposition process and is potentially suitable for high-throughput, large-volume, and low-cost production. In particular, this strategy enables fabrication of a high-aspect-ratio (thickness to linewidth) metal mesh, substantially improving conductivity without considerably sacrificing transparency. Various prototype flexible transparent electrodes are demonstrated with transmittance higher than 90% and sheet resistance below 1 ohm sq(-1) , as well as extremely high figures of merit up to 1.5 × 10(4) , which are among the highest reported values in recent studies. Finally using our embedded metal-mesh electrode, a flexible transparent thin-film heater is demonstrated with a low power density requirement, rapid response time, and a low operating voltage. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of Lightweight Radiation Shielding Composite Materials by Field Assisted Sintering Technique (FAST)

NASA Technical Reports Server (NTRS)

Prasad, Narasimha; Trivedi, Sudhir; Chen, Henry; Kutcher, Susan; Zhang, Dajie; Singh, Jogender

2017-01-01

Advances in radiation shielding technologies are needed to protect humans and electronic components from all threats of space radiation over long durations. In this paper, we report on the use of the innovative and novel fabrication technology known as Field Assisted Sintering Technology (FAST) to fabricate lightweight material with enhanced radiation shielding strength to safeguard humans and electronics suitable for next generation space exploration missions. The base materials we investigated were aluminum (Al), the current standard material for space hardware, and Ultra-High Molecular Weight Polyethylene (UHMWPE), which has high hydrogen content and resistance to nuclear reaction from neutrons, making it a good shielding material for both gamma radiation and particles. UHMWPE also has high resistance to corrosive chemicals, extremely low moisture sensitivity, very low coefficient of friction, and high resistance to abrasion. We reinforced the base materials by adding high density (ie, high atomic weight) metallic material into the composite. These filler materials included: boron carbide (B4C), tungsten (W), tungsten carbide (WC) and gadolinium (Gd).

Fabrication of low loss waveguide using fundamental light of Yb-based femtosecond laser (Conference Presentation)

NASA Astrophysics Data System (ADS)

Imai, Ryo; Konishi, Kuniaki; Yumoto, Junji; Gonokami, Makoto K.

2017-03-01

Laser direct writing of optical devices and circuits is attracted attention because of its ability of three-dimensional fabrication without any mask[1]. Recently, Yb-fiber or solid-state laser has been commonly used for fabrication in addition to traditional Ti:S laser. However, it is reported that waveguide cannot be fabricated in fused silica by using the fundamental light from Yb-based femtosecond laser[2]. Some groups reported on waveguide fabrication by using second-harmonic beam of such lasers[3], but wavelength conversion using nonlinear process has drawbacks such as destabilization of laser power and beam deformation by walk off. In this study, we investigated fabrication of low-loss waveguide in fused silica by using the fundamental beam (1030nm) from an Yb solid-state femtosecond laser with a pulse duration of 250 fs. The NA of focusing objective lens was 0.42. The fabricated waveguide was made to have a circular cross-section by shaping laser beam with a slit[4]. We fixed repetition rate to 150 kHz, and identified appropriate scan speed and pulse energy for fabrication of low loss waveguide. Waveguide fabricated with appropriate condition had a propagation loss of 0.2 dB/cm, and this is the first report on optical waveguides in a fused silica fabricated by femto-second laser pulses at a wavelength of 1030nm. [1]K. M. Davis, et. al., Opt. Lett 21, 1729(1996) [2]J. Canning, et. al., Opt. Mater. Express 1, 998(2011) [3]L. Shah, et. al., Opt. Express 13, 1999(2005) [4]M. Ams, et. al., Opt. Express 13, 5676(2005)

Label-free screening of single biomolecules through resistive pulse sensing technology for precision medicine applications

NASA Astrophysics Data System (ADS)

Harrer, S.; Kim, S. C.; Schieber, C.; Kannam, S.; Gunn, N.; Moore, S.; Scott, D.; Bathgate, R.; Skafidas, S.; Wagner, J. M.

2015-05-01

Employing integrated nano- and microfluidic circuits for detecting and characterizing biological compounds through resistive pulse sensing technology is a vibrant area of research at the interface of biotechnology and nanotechnology. Resistive pulse sensing platforms can be customized to study virtually any particle of choice which can be threaded through a fluidic channel and enable label-free single-particle interrogation with the primary read-out signal being an electric current fingerprint. The ability to perform label-free molecular screening with single-molecule and even single binding site resolution makes resistive pulse sensing technology a powerful tool for analyzing the smallest units of biological systems and how they interact with each other on a molecular level. This task is at the core of experimental systems biology and in particular ‘omics research which in combination with next-generation DNA-sequencing and next-generation drug discovery and design forms the foundation of a novel disruptive medical paradigm commonly referred to as personalized medicine or precision medicine. DNA-sequencing has approached the 1000-Dollar-Genome milestone allowing for decoding a complete human genome with unmatched speed and at low cost. Increased sequencing efficiency yields massive amounts of genomic data. Analyzing this data in combination with medical and biometric health data eventually enables understanding the pathways from individual genes to physiological functions. Access to this information triggers fundamental questions for doctors and patients alike: what are the chances of an outbreak for a specific disease? Can individual risks be managed and if so how? Which drugs are available and how should they be applied? Could a new drug be tailored to an individual’s genetic predisposition fast and in an affordable way? In order to provide answers and real-life value to patients, the rapid evolvement of novel computing approaches for analyzing big data in

Label-free screening of single biomolecules through resistive pulse sensing technology for precision medicine applications.

PubMed

Harrer, S; Kim, S C; Schieber, C; Kannam, S; Gunn, N; Moore, S; Scott, D; Bathgate, R; Skafidas, S; Wagner, J M

2015-05-08

Employing integrated nano- and microfluidic circuits for detecting and characterizing biological compounds through resistive pulse sensing technology is a vibrant area of research at the interface of biotechnology and nanotechnology. Resistive pulse sensing platforms can be customized to study virtually any particle of choice which can be threaded through a fluidic channel and enable label-free single-particle interrogation with the primary read-out signal being an electric current fingerprint. The ability to perform label-free molecular screening with single-molecule and even single binding site resolution makes resistive pulse sensing technology a powerful tool for analyzing the smallest units of biological systems and how they interact with each other on a molecular level. This task is at the core of experimental systems biology and in particular 'omics research which in combination with next-generation DNA-sequencing and next-generation drug discovery and design forms the foundation of a novel disruptive medical paradigm commonly referred to as personalized medicine or precision medicine. DNA-sequencing has approached the 1000-Dollar-Genome milestone allowing for decoding a complete human genome with unmatched speed and at low cost. Increased sequencing efficiency yields massive amounts of genomic data. Analyzing this data in combination with medical and biometric health data eventually enables understanding the pathways from individual genes to physiological functions. Access to this information triggers fundamental questions for doctors and patients alike: what are the chances of an outbreak for a specific disease? Can individual risks be managed and if so how? Which drugs are available and how should they be applied? Could a new drug be tailored to an individual's genetic predisposition fast and in an affordable way? In order to provide answers and real-life value to patients, the rapid evolvement of novel computing approaches for analyzing big data in

Fabrication of spherical microlens array by combining lapping on silicon wafer and rapid surface molding

NASA Astrophysics Data System (ADS)

Liu, Xiaohua; Zhou, Tianfeng; Zhang, Lin; Zhou, Wenchen; Yu, Jianfeng; Lee, L. James; Yi, Allen Y.

2018-07-01

Silicon is a promising mold material for compression molding because of its properties of hardness and abrasion resistance. Silicon wafers with carbide-bonded graphene coating and micro-patterns were evaluated as molds for the fabrication of microlens arrays. This study presents an efficient but flexible manufacturing method for microlens arrays that combines a lapping method and a rapid molding procedure. Unlike conventional processes for microstructures on silicon wafers, such as diamond machining and photolithography, this research demonstrates a unique approach by employing precision steel balls and diamond slurries to create microlenses with accurate geometry. The feasibility of this method was demonstrated by the fabrication of several microlens arrays with different aperture sizes and pitches on silicon molds. The geometrical accuracy and surface roughness of the microlens arrays were measured using an optical profiler. The measurement results indicated good agreement with the optical profile of the design. The silicon molds were then used to copy the microstructures onto polymer substrates. The uniformity and quality of the samples molded through rapid surface molding were also assessed and statistically quantified. To further evaluate the optical functionality of the molded microlens arrays, the focal lengths of the microlens arrays were measured using a simple optical setup. The measurements showed that the microlens arrays molded in this research were compatible with conventional manufacturing methods. This research demonstrated an alternative low-cost and efficient method for microstructure fabrication on silicon wafers, together with the follow-up optical molding processes.

B-type olivine fabric induced by low temperature dissolution creep during serpentinization and deformation in mantle wedge

NASA Astrophysics Data System (ADS)

Liu, Wenlong; Zhang, Junfeng; Barou, Fabrice

2018-01-01

The B-type olivine fabric (i.e., the [010] axes subnormal to foliation and the [001] axes subparallel to the lineation) has been regarded as an important olivine fabric for interpreting global trench-parallel S-wave polarization in fore-arc regions. However, strong serpentinization and cold temperature environment in the mantle wedge should inhibit development of the B-type olivine fabric that requires high temperature to activate solid-state plastic deformation. Here we report fabrics of olivine and antigorite generated at low temperatures (300-370 °C) during serpentinization in a fossil mantle wedge of the Val Malenco area, Central Alps. Olivine in the serpentine matrix develops a pronounced B-type fabric, while antigorite in the same matrix displays a strong crystallographic preferred orientation (CPO) with the (001) planes and the [010] axes subparallel to foliation and lineation, respectively. The following evidence leads to the conclusion that the B-type olivine fabric results from dissolution creep assisted by grain boundary sliding (GBS) and grain rotation, rather than solid-state plastic deformation: (1) serpentinization took place at low temperatures and a fluid-enriched environment, ideal for dissolution-precipitation creep; (2) the voids and zigzag boundaries along the interface between antigorite and olivine suggest a fluid dissolution reaction; (3) the primary coarse olivine develops a nearly random fabric, indicating the B-type fabrics in the fine-grained olivine may not be inherited fabrics. These results document for the first time the B-type olivine CPO formed by dissolution creep at low temperatures during serpentinization and provide a mechanism to reconcile petrofabric observations with geophysical observations of trench parallel fast S-wave seismic anisotropy in fore-arc mantle wedge regions.

Low-load resistance training with low relative pressure produces muscular changes similar to high-load resistance training.

PubMed

Kim, Daeyeol; Loenneke, Jeremy P; Ye, Xin; Bemben, Debra A; Beck, Travis W; Larson, Rebecca D; Bemben, Michael G

2017-12-01

This study compares the acute and chronic response of high-load resistance training (HL) to low-load resistance training with low blood flow restriction (LL-BFR) pressure. Participants completed elbow flexion with either HL or LL-BFR or nonexercise. In the chronic study, participants in the HL and LL-BFR groups were trained for 8 weeks to determine differences in muscle size and strength. The acute study examined the changes in pretesting/posttesting (Pre/Post) torque, muscle swelling, and blood lactate. In the chronic study, similar changes in muscle size and strength were observed for both HL and LL-BFR. In the acute study, Pre/Post changes in the torque, muscle swelling, and blood lactate were similar between HL and LL-BFR. Our findings indicate that pressure as low as 50% arterial occlusion can produce similar changes in muscle mass and strength compared with traditional HL. Muscle Nerve 56: E126-E133, 2017. © 2017 Wiley Periodicals, Inc.

Fabrication of brittle materials -- current status

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scattergood, R.O.

The research initiatives in the area of precision fabrication will be continued in the upcoming year. Three students, T. Bifano (PhD), P. Blake (PhD) and E. Smith (MS), finished their research programs in the last year. Sections 13 and 14 will summarize the essential results from the work of the Materials Engineering students Blake and Smith. Further details will be presented in forthcoming publications that are now in preparation. The results from Bifano`s thesis have been published in adequate detail and need not be summarized further. Three new students, S. Blackley (MS), H. Paul (PhD), and S. Smith (PhD) havemore » joined the program and will continue the research efforts in precision fabrication. The programs for these students will be outlined in Sections 15 and 16. Because of the success of the earlier work in establishing new process models and experimental techniques for the study of diamond turning and diamond grinding, the new programs will, in part, build upon the earlier work. This is especially true for investigations concerned with brittle materials. The basic understanding of material response of nominally brittle materials during machining or grinding operations remains as a challenge. The precision fabrication of brittle materials will continue as an area of emphasis for the Precision Engineering Center.« less

Design, fabrication and characterization of LTCC-based electromagnetic microgenerators

NASA Astrophysics Data System (ADS)

Gierczak, M.; Markowski, P.; Dziedzic, A.

2016-02-01

Design, manufacturing process and properties of electromagnetic microgenerators fabricated in LTCC (Low Temperature Co-fired Ceramics) technology are presented in this paper. Electromagnetic microgenerators consist of planar coils spatially arranged on several layers of LTCC and of a multipole permanent magnet. Two different patterns of coils with 2-, 8-,10- and 12-layers and outer diameter of 50 mm were designed and fabricated. Silver-based pastes ESL 903-A or DuPont 6145 were used. In order to estimate the inductance of a single spatial coil the Greenhouse (self-inductance) and Hoer (mutual inductance) calculation methods were used. To verify the calculation results a single-layer coil was fabricated for each pattern and its inductance was measured using the precision RLC Meter. Fabricated LTCC microgenerators with embedded coils allow to generate voltage higher than ten volts and the electrical output power of approximately 600 mW at the rotor rotation speed of 12 thousands rpm. The self-made system was used for characterization of LTCC-based electromagnetic microgenerators.

Fabrication of micro-optical components using femtosecond oscillator pulses

NASA Astrophysics Data System (ADS)

Rodrigues, Vanessa R. M.; Ramachandran, Hema; Chidangil, Santhosh; Mathur, Deepak

2017-06-01

With a penchant for integrated photonics and miniaturization, the fabrication of micron sized optical elements using precision laser pulse management is drawing attention due to the possibility of minimizing tolerances for collateral material damage. The work presented here deals with the design, fabrication and characterization of a range of diffractive optics - gratings, grids and Fresnel zone plates - on transparent and metallic samples. Their low volume, light weight, transmission bandwidth, high damage threshold and flexible design make them suited for replacing conventional refractive optical elements. Our one-step, mask-less, 3-D laser direct writing process is a green fabrication technique which is in stark contrast to currently popular Photo-lithography based micro-structuring. Our method provides scope for modifications on the surface as well as within the bulk of the material. The mechanism involved in the fabrication of these optics on transparent and thin metallic substrates differ from each other. Our studies show that both amplitude and phase versions of micro-structures were achieved successfully with performances bearing 98% accuracy vis-a-vis theoretical expectations.

Off-plane x-ray reflection grating fabrication

NASA Astrophysics Data System (ADS)

Peterson, Thomas J.; DeRoo, Casey T.; Marlowe, Hannah; McEntaffer, Randall L.; Miles, Drew M.; Tutt, James H.; Schultz, Ted B.

2015-09-01

Off-plane X-ray diffraction gratings with precision groove profiles at the submicron scale will be used in next generation X-ray spectrometers. Such gratings will be used on a current NASA suborbital rocket mission, the Off-plane Grating Rocket Experiment (OGRE), and have application for future grating missions. The fabrication of these gratings does not come without challenges. High performance off-plane gratings must be fabricated with precise radial grating patterns, optically at surfaces, and specific facet angles. Such gratings can be made using a series of common micro-fabrication techniques. The resulting process is highly customizable, making it useful for a variety of different mission architectures. In this paper, we detail the fabrication method used to produce high performance off-plane gratings and report the results of a preliminary qualification test of a grating fabricated in this manner. The grating was tested in the off-plane `Littrow' configuration, for which the grating is most efficient for a given diffraction order, and found to achieve 42% relative efficiency in the blaze order with respect to all diffracted light.

Fabrication of GRCop-84 Rocket Thrust Chambers

NASA Technical Reports Server (NTRS)

Loewenthal, William; Ellis, David

2006-01-01

GRCop-84, a copper alloy, Cu-8 at% Cr-4 at% Nb developed at NASA Glenn Research Center for regenerative1y cooled rocket engine liners has excellent combinations of elevated temperature strength, creep resistance, thermal conductivity and low cycle fatigue. GRCop-84 is produced from pre-alloyed atomized powder and has been fabricated into plate, sheet and tube forms as well as near net shapes. Fabrication processes to produce demonstration rocket combustion chambers will be presented and includes powder production, extruding, rolling, forming, friction stir welding, and metal spinning. GRCop-84 has excellent workability and can be readily fabricated into complex components using conventional powder and wrought metallurgy processes. Rolling was examined in detail for process sensitivity at various levels of total reduction, rolling speed and rolling temperature representing extremes of commercial processing conditions. Results indicate that process conditions can range over reasonable levels without any negative impact to properties.

Fabrication of GRCop-84 Rocket Thrust Chambers

NASA Technical Reports Server (NTRS)

Loewenthal, William S.; Ellis, David L.

2005-01-01

GRCop-84, a copper alloy, Cu-8 at% Cr-4 at% Nb developed at NASA Glenn Research Center for regeneratively cooled rocket engine liners has excellent combinations of elevated temperature strength, creep resistance, thermal conductivity and low cycle fatigue. GRCop-84 is produced from prealloyed atomized powder and has been fabricated into plate, sheet and tube forms as well as near net shapes. Fabrication processes to produce demonstration rocket combustion chambers will be presented and includes powder production, extruding, rolling, forming, friction stir welding, and metal spinning. GRCop-84 has excellent workability and can be readily fabricated into complex components using conventional powder and wrought metallurgy processes. Rolling was examined in detail for process sensitivity at various levels of total reduction, rolling speed and rolling temperature representing extremes of commercial processing conditions. Results indicate that process conditions can range over reasonable levels without any negative impact to properties.

Fabrication of micro-patterned aluminum surfaces for low ice adhesion strength

NASA Astrophysics Data System (ADS)

Jeon, Jaehyeon; Jang, Hanmin; Chang, Jinho; Lee, Kwan-Soo; Kim, Dong Rip

2018-05-01

We report a fabrication method to obtain a low-ice-adhesion aluminum surface by surface texturing using solution etching and subsequent thin-film coating. Specifically, the textured surface has microstructures of a low aspect ratio, that is, with a much smaller height than width. Such microstructures can effectively reduce ice-adhesion strengths by sliding the ice during detachment. Because our method is based on solution etching, it can be applied to curved surfaces with complex shapes for uniformly constructing the morphology of a low-ice-adhesion aluminum surface. Finally, the low-ice-adhesion aluminum surface reduces the ice-adhesion strengths by up to 95%.

Fabrication of superhydrophobic Pt3Fe/Fe surface for its application

NASA Astrophysics Data System (ADS)

Cui, Shuo; Lu, Shixiang; Xu, Wenguo; Wu, Bei

2017-10-01

Well-defined Pt3Fe/Fe superhydrophobic materials on iron sheet with special properties, such as corrosion resistance, superhydrophobicity and superoleophilicity, was fabricated. The fabrication process involved etching in hydrochloric acid aqueous solution and simple replacement deposition process without using any seed and organic solvent, and then annealing. The electrochemical measurements show that the resultant surface in 3.5% sodium chloride solution displays good corrosion resistance. Also, it is proved that the obtained surface has better mechanical abrasion resistance via scratch test. The superoleophilicity and low water adhesion force of the obtained surface endow it high oil/water separation capacity. The as-prepared nanocomposites display enhanced catalytic activity and kinetics toward degradation of methyl orange. In particular, it possesses the most efficient degradation capacity (95%) towards methyl orange at a high concentration (17.5 mg/L) in 80 min. The improved stability and excellent catalytic activity of the Pt3Fe/Fe nanocomposites promise new opportunities for the development of waste water treatment.

Low-cost zinc-plated photoanode for fabric-type dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Kong, Lingfeng; Bao, Yunna; Guo, Wanwan; Cheng, Li; Du, Jun; Liu, Renlong; Wang, Yundong; Fan, Xing; Tao, Changyuan

2016-02-01

Fabric-type flexible solar cells have been recently proposed as a very promising power source for wearable electronics. To increase the photocurrent of fabric-type flexible solar cells, low-cost zinc-plated wire and mesh photoanodes are assembled for the first time through a mild wet process. Given the protection of the compact protection layer, the DSSC device could benefit from the low work function of Zn and self-repairing behavior on the Zn/ZnO interface. An evident current increase by ∼6 mA/cm2 could be observed after coating a layer of metal Zn on various metal substrates, such as traditional stainless steel wire. Given the self-repairing behavior on Zn/ZnO interface, the Zn layer can help to improve the interfacial carrier transfer, leading to better photovoltaic performance, for both liquid-type and solid-type cells.

Low friction wear resistant graphene films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sumant, Anirudha V.; Berman, Diana; Erdemir, Ali

A low friction wear surface with a coefficient of friction in the superlubric regime including graphene and nanoparticles on the wear surface is provided, and methods of producing the low friction wear surface are also provided. A long lifetime wear resistant surface including graphene exposed to hydrogen is provided, including methods of increasing the lifetime of graphene containing wear surfaces by providing hydrogen to the wear surface.

Fabrication Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 ismore » 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.« less

Fabrication technology

NASA Astrophysics Data System (ADS)

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 do the following: (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 U.S. 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.

Low resistance barrier layer for isolating, adhering, and passivating copper metal in semiconductor fabrication

DOEpatents

Weihs, Timothy P.; Barbee, Jr., Troy W.

2002-01-01

Cubic or metastable cubic refractory metal carbides act as barrier layers to isolate, adhere, and passivate copper in semiconductor fabrication. One or more barrier layers of the metal carbide are deposited in conjunction with copper metallizations to form a multilayer characterized by a cubic crystal structure with a strong (100) texture. Suitable barrier layer materials include refractory transition metal carbides such as vanadium carbide (VC), niobium carbide (NbC), tantalum carbide (TaC), chromium carbide (Cr.sub.3 C.sub.2), tungsten carbide (WC), and molybdenum carbide (MoC).

Tuning the resistive switching properties of TiO2-x films

NASA Astrophysics Data System (ADS)

Ghenzi, N.; Rozenberg, M. J.; Llopis, R.; Levy, P.; Hueso, L. E.; Stoliar, P.

2015-03-01

We study the electrical characteristics of TiO2-x-based resistive switching devices fabricated with different oxygen/argon flow ratio during the oxide thin film sputtering deposition. Upon minute changes in this fabrication parameter, three qualitatively different device characteristics were accessed in the same system, namely, standard bipolar resistive switching, electroforming-free devices, and devices with multi-step breakdown. We propose that small variations in the oxygen/ argon flow ratio result in relevant changes of the oxygen vacancy concentration, which is the key parameter determining the resistive switching behavior. The coexistence of percolative or non-percolative conductive filaments is also discussed. Finally, the hypothesis is verified by means of the temperature dependence of the devices in low resistance state.

Paper-based membraneless hydrogen peroxide fuel cell prepared by micro-fabrication

NASA Astrophysics Data System (ADS)

Mousavi Ehteshami, Seyyed Mohsen; Asadnia, Mohsen; Tan, Swee Ngin; Chan, Siew Hwa

2016-01-01

A paper-based membraneless single-compartment hydrogen peroxide power source prepared by micro-electromechanical systems (MEMS) technology is reported. The cell utilizes hydrogen peroxide as both fuel and oxidant in a low volume cell fabricated on paper. The fabrication method used is a simple method where precise, small-sized patterns are produced which include the hydrophilic paper bounded by hydrophobic resin. Open circuit potentials of 0.61 V and 0.32 V are achieved for the cells fabricated with Prussian Blue as the cathode and aluminium/nickel as the anode materials, respectively. The power produced by the cells is 0.81 mW cm-2 at 0.26 V and 0.38 mW cm-2 at 0.14 V, respectively, even after the cell is bent or distorted. Such a fuel cell provides an easily fabricated, environmentally friendly, flexible and cost saving power source. The cell may be integrated within a self-sustained diagnostic system to provide the on-demand power for future bio-sensing applications.

Low temperature fabrication of VO x thin films for uncooled IR detectors by direct current reactive magnetron sputtering method

NASA Astrophysics Data System (ADS)

Dai, Jun; Wang, Xingzhi; He, Shaowei; Huang, Ying; Yi, Xinjian

2008-03-01

Vanadium oxide films have been fabricated on Si3N4-film-coated silicon substrates by direct current reactive magnetron sputtering method. Conditions of deposition are optimized making use of parameters such as sputtering time, dc power, oxygen partial pressure and substrate temperature. X-ray diffraction indicates that the film is a mixture of VO2, V2O3, and V3O5. Four-probe measurement shows that the VOx thin film owns high temperature coefficient of resistance (TCR ∼-2.05%/°C) and suitable square resistance 18.40 kΩ/□ (measured at 25 °C), indicating it is a well candidate material for uncooled IR detectors. In addition, IR absorption in the wavelength of 2-16 μm has been characterized. It is worth noting that the films are sputtered at a relatively low temperature of 210 °C in a controlled Ar/O2 atmosphere. Compared to traditional craft, this method needs no post-anneal at high temperature (400-500 °C).

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.

Systems and Methods for Fabricating Structures Including Metallic Glass-Based Materials Using Low Pressure Casting

NASA Technical Reports Server (NTRS)

Hofmann, Douglas C. (Inventor); Kennett, Andrew (Inventor)

2018-01-01

Systems and methods to fabricate objects including metallic glass-based materials using low-pressure casting techniques are described. In one embodiment, a method of fabricating an object that includes a metallic glass-based material includes: introducing molten alloy into a mold cavity defined by a mold using a low enough pressure such that the molten alloy does not conform to features of the mold cavity that are smaller than 100 microns; and cooling the molten alloy such that it solidifies, the solid including a metallic glass-based material.

Thermoelectric microdevice fabricated by a MEMS-like electrochemical process

NASA Technical Reports Server (NTRS)

Snyder, G. Jeffrey; Lim, James R.; Huang, Chen-Kuo; Fleurial, Jean-Pierre

2003-01-01

Microelectromechanical systems (MEMS) are the basis of many rapidly growing technologies, because they combine miniature sensors and actuators with communications and electronics at low cost. Commercial MEMS fabrication processes are limited to silicon-based materials or two-dimensional structures. Here we show an inexpensive, electrochemical technique to build MEMS-like structures that contain several different metals and semiconductors with three-dimensional bridging structures. We demonstrate this technique by building a working microthermoelectric device. Using repeated exposure and development of multiple photoresist layers, several different metals and thermoelectric materials are fabricated in a three-dimensional structure. A device containing 126 n-type and p-type (Bi, Sb)2Te3 thermoelectric elements, 20 microm tall and 60 microm in diameter with bridging metal interconnects, was fabricated and cooling demonstrated. Such a device should be of technological importance for precise thermal control when operating as a cooler, and for portable power when operating as a micro power generator.

High Precision Low-blank Lithium Isotope Ratios in Forams.

NASA Astrophysics Data System (ADS)

Misra, S.; Froelich, P. N.

2007-12-01

We present a high precision (±1‰, 2σ) low blank (<500 fg/ml) method for Li isotope measurements of forams using <2 ng of Li by single collector Quad ICP-MS (Agilent 7500cs). The Li isotope ratio of seawater (δ7Li) recorded in planktonic forams has the potential to constrain the evolution of seawater chemistry and elucidate the factors driving variations of oceanic mass balances linked to the continental and sea floor/hydrothermal silica cycles. In addition a δ7Li record of seawater will complement other long-term recorders of seawater chemistry such as Sr, Os and S isotopes. Li isotope measurements of forams are limited by several factors: low Li concentrations in forams (1-2 ppm), instrument-induced fractionation and mass bias effects, matrix effects, high Li blanks and incomplete recovery of Li during column separation. Modest concentrations of alkali and alkaline earth elements in the matrix result in variable mass bias in measured Li isotope ratios. Even worse, Li strongly fractionates during chromatographic clean-up to remove Na+, Ca2+ and Mg2+, from +100‰ in the leading edge to - 100‰ in the trailing edge of elution peaks (Urey 1938). Consequently, miniscule incomplete recoveries of Li during chromatographic separations can result in large unrecognized isotope fractionation of eluents. Large mass-dependent fractionation caused by a difference of 17% in mass between 6Li and 7Li, makes Li a powerful tracer of geochemical processes, but also promotes large and difficult-to-fix isotope fractionations during laboratory chemical processing. Matrix effects of Na & Ca and of column chromatography on Li isotope ratios were investigated using artificial Li solutions representative of foram compositions (matrix matching). Li/Ca and Li/Na ratios in cleaned forams are 10 μmol/mol and 3 mmol/mol respectively. An ICP-MS tolerance limit of 20 ppb for Na and 20 μM for Ca was established, much higher tolerances than by TIMS. A single step chromatographic method to

Productive Nanosystems: The Physics of Molecular Fabrication

ERIC Educational Resources Information Center

Drexler, K. Eric

2005-01-01

Fabrication techniques are the foundation of physical technology, and are thus of fundamental interest. Physical principles indicate that nanoscale systems will be able to fabricate a wide range of structures, operating with high productivity and precise molecular control. Advanced systems of this kind will require intermediate generations of…

Fabricating binary optics: An overview of binary optics process technology

NASA Technical Reports Server (NTRS)

Stern, Margaret B.

1993-01-01

A review of binary optics processing technology is presented. Pattern replication techniques have been optimized to generate high-quality efficient microoptics in visible and infrared materials. High resolution optical photolithography and precision alignment is used to fabricate maximally efficient fused silica diffractive microlenses at lambda = 633 nm. The degradation in optical efficiency of four-phase-level fused silica microlenses resulting from an intentional 0.35 micron translational error has been systematically measured as a function of lens speed (F/2 - F/60). Novel processes necessary for high sag refractive IR microoptics arrays, including deep anisotropic Si-etching, planarization of deep topography and multilayer resist techniques, are described. Initial results are presented for monolithic integration of photonic and microoptic systems.

Flexible inverted polymer solar cells fabricated in air at low temperatures

NASA Astrophysics Data System (ADS)

Kuwabara, Takayuki; Wang, Xiaofan; Kusumi, Takuji; Yamaguchi, Takahiro; Taima, Tetsuya; Takahashi, Kohshin

2016-08-01

A series of modified indium tin oxide (ITO) materials, including sol-gel zinc-oxide-coated ITO (ITO/ZnO), ZnO nanoparticle-coated ITO (ITO/ZnO-NP), 1,4-bis(3-aminopropyl)piperazine (BAP)-modified ITO, and polyethylenimine ethoxylated (PEIE)-modified ITO, were used for electron-collection electrodes in inverted polymer solar cells (PSCs). The modified ITO electrodes were prepared in air at temperatures below 100 °C, using various ITO films on flexible poly(ethylene terephthalate) substrates (PET-ITO) with sheet resistances ranging from 12 to 60 Ω sq-1. The PET-ITO (12 Ω sq-1)/ZnO-NP PSC exhibited an improved power conversion efficiency (PCE) (2.93%), and this PCE was ˜90% of that observed for a cell using glass-ITO/ZnO-NP (sheet resistance = 10 Ω sq-1 PCE = 3.28%). Additionally, we fabricated a flexible inverted ZnO-NP PSC using an indene-C60 bisadduct (ICBA) as the acceptor material in place of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and obtained a PCE of 4.18%.

Quantization and training of object detection networks with low-precision weights and activations

NASA Astrophysics Data System (ADS)

Yang, Bo; Liu, Jian; Zhou, Li; Wang, Yun; Chen, Jie

2018-01-01

As convolutional neural networks have demonstrated state-of-the-art performance in object recognition and detection, there is a growing need for deploying these systems on resource-constrained mobile platforms. However, the computational burden and energy consumption of inference for these networks are significantly higher than what most low-power devices can afford. To address these limitations, this paper proposes a method to train object detection networks with low-precision weights and activations. The probability density functions of weights and activations of each layer are first directly estimated using piecewise Gaussian models. Then, the optimal quantization intervals and step sizes for each convolution layer are adaptively determined according to the distribution of weights and activations. As the most computationally expensive convolutions can be replaced by effective fixed point operations, the proposed method can drastically reduce computation complexity and memory footprint. Performing on the tiny you only look once (YOLO) and YOLO architectures, the proposed method achieves comparable accuracy to their 32-bit counterparts. As an illustration, the proposed 4-bit and 8-bit quantized versions of the YOLO model achieve a mean average precision of 62.6% and 63.9%, respectively, on the Pascal visual object classes 2012 test dataset. The mAP of the 32-bit full-precision baseline model is 64.0%.

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, Jr., Troy W.; Johnson, Gary W.; O'Brien, Dennis W.

1995-01-01

A high performance capacitor fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a "notepad" configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The "notepad" capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density.

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, Jr., Troy W.; Johnson, Gary W.; O'Brien, Dennis W.

1996-01-01

A high performance capacitor fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a "notepad" configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The "notepad" capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density.

Precision of Times-of-Minima and the Detection of Low-Mass Third Bodies Orbiting Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Genet, R. M.; Smith, T. C.

2004-12-01

Low-mass third bodies orbiting eclipsing binaries are difficult to detect by way of periodic shifts in photometric times-of-minima because the observational precision of these timings are of the same order as the expected effects of any low-mass companions. We are implementing three approaches to increasing the precision of our times-of-minima. First, we are obtaining many times-of-minima by utilizing relatively low-cost, dedicated telescopes and CCD cameras (10- and 14-inch Meade LX-200 telescopes and SBIG ST7-XE cameras). Operating in a semiautomatic mode, we select an eclipsing binary system, based on its placement in the sky, and observe it all night long - usually many nights in a row. We choose binaries with short enough periods to assure us of obtaining a complete light curve (and hence an eclipse) every night we observe. Second, we are striving to increase the photometric precision of each observation through the use of multiple comparison stars (ensemble photometry). We are also, in conjunction with California Polytechnic State University, investigating other ways of increasing the photometric precision of these low-cost systems (see E. Sturm this conference). Finally, we are utilizing complete, as opposed to partial, light curves in our analysis. Information outside primary eclipses is gathered as a matter of course, and its use can improve precision. A total of 186 complete light curves were obtained at the Dark Ridge and Orion Observatories during the 2004 observing season on six eclipsing binaries (TZ Boo, V523 Cas, RW Com, V1191 Cyg, GM Dra, and V400 Lyr). Please see T. Smith and R. Genet (this conference) for preliminary results on V523 Cas (30+ complete light curves).

Bipolar resistive switching of single gold-in-Ga2O3 nanowire.

PubMed

Hsu, Chia-Wei; Chou, Li-Jen

2012-08-08

We have fabricated single nanowire chips on gold-in-Ga(2)O(3) core-shell nanowires using the electron-beam lithography techniques and realized bipolar resistive switching characteristics having invariable set and reset voltages. We attribute the unique property of invariance to the built-in conduction path of gold core. This invariance allows us to fabricate many resistive switching cells with the same operating voltage by simple depositing repetitive metal electrodes along a single nanowire. Other characteristics of these core-shell resistive switching nanowires include comparable driving electric field with other thin film and nanowire devices and a remarkable on/off ratio more than 3 orders of magnitude at a low driving voltage of 2 V. A smaller but still impressive on/off ratio of 10 can be obtained at an even lower bias of 0.2 V. These characteristics of gold-in-Ga(2)O(3) core-shell nanowires make fabrication of future high-density resistive memory devices possible.

Fabrics coated with lubricated nanostructures display robust omniphobicity

DOE PAGES

Shillingford, Cicely; MacCallum, Noah; Wong, Tak -Sing; ...

2013-12-11

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e.g., rain), and whenmore » exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. However we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.« less

Fabrics coated with lubricated nanostructures display robust omniphobicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shillingford, C; MacCallum, N; Wong, TS

2013-12-11

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e. g., rain), andmore » when exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. Herein we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.« less

Fabrics coated with lubricated nanostructures display robust omniphobicity.

PubMed

Shillingford, Cicely; MacCallum, Noah; Wong, Tak-Sing; Kim, Philseok; Aizenberg, Joanna

2014-01-10

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e.g., rain), and when exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. Herein we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.

Fabrics coated with lubricated nanostructures display robust omniphobicity

NASA Astrophysics Data System (ADS)

Shillingford, Cicely; MacCallum, Noah; Wong, Tak-Sing; Kim, Philseok; Aizenberg, Joanna

2014-01-01

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e.g., rain), and when exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. Herein we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.

a Precise, Low-Cost Rtk Gnss System for Uav Applications

NASA Astrophysics Data System (ADS)

Stempfhuber, W.; Buchholz, M.

2011-09-01

High accuracy with real-time positioning of moving objects has been considered a standard task of engineering geodesy for 10 to 15 years. An absolute positioning accuracy of 1-3 cm is generally possible worldwide and is further used in many areas of machine guidance (machine control and guidance), and farming (precision farming) as well as for various special applications (e.g. railway trolley, mining, etc.). The cost of the measuring instruments required for the use of geodetic L1/L2 receivers with a local reference station amounts to approximately USD 30,000 to 50,000. Therefore, dual frequency RTK GNSS receivers are not used in the mass market. Affordable GPS/GNSS modules have already reached the mass market in various areas such as mobile phones, car navigation, the leisure industry, etc. Kinematic real-time positioning applications with centimetre or decimetre levels could also evolve into a mass product. In order for this to happen, the costs for such systems must lie between USD 1,000 to 2,000. What exactly low-cost means is determined by the precise specifications of the given individual application. Several university studies in geodesy focus on the approach of high-accuracy positioning by means of single frequency receivers for static applications [e.g. GLABSCH et. al. 2009, SCHWIEGER and GLÄSER 2005, ALKAN 2010, REALINI et. al. 2010, KORTH and HOFMANN 2011]. Although intelligent approaches have been developed that compute a trajectory in the post-processing mode [REALINI et. al., 2010], at present, there are only a very few GNSS Low-Cost Systems that enable real-time processing. This approach to precise position determination by means of the computation of static raw data with single frequency receivers is currently being explored in a research project at the Beuth Hochschule für Technik Berlin - and is being further developed for kinematic applications. The project is embedded in the European Social Fund. It is a follow-up project in the area of

Automatic Fabric Defect Detection with a Multi-Scale Convolutional Denoising Autoencoder Network Model.

PubMed

Mei, Shuang; Wang, Yudan; Wen, Guojun

2018-04-02

Fabric defect detection is a necessary and essential step of quality control in the textile manufacturing industry. Traditional fabric inspections are usually performed by manual visual methods, which are low in efficiency and poor in precision for long-term industrial applications. In this paper, we propose an unsupervised learning-based automated approach to detect and localize fabric defects without any manual intervention. This approach is used to reconstruct image patches with a convolutional denoising autoencoder network at multiple Gaussian pyramid levels and to synthesize detection results from the corresponding resolution channels. The reconstruction residual of each image patch is used as the indicator for direct pixel-wise prediction. By segmenting and synthesizing the reconstruction residual map at each resolution level, the final inspection result can be generated. This newly developed method has several prominent advantages for fabric defect detection. First, it can be trained with only a small amount of defect-free samples. This is especially important for situations in which collecting large amounts of defective samples is difficult and impracticable. Second, owing to the multi-modal integration strategy, it is relatively more robust and accurate compared to general inspection methods (the results at each resolution level can be viewed as a modality). Third, according to our results, it can address multiple types of textile fabrics, from simple to more complex. Experimental results demonstrate that the proposed model is robust and yields good overall performance with high precision and acceptable recall rates.

Pyrethroid resistance alters the blood-feeding behavior in Puerto Rican Aedes aegypti mosquitoes exposed to treated fabric

PubMed Central

Bloomquist, Jeffrey R.; Bernier, Ulrich R.

2017-01-01

Emerging insecticide resistance is a major issue for vector control. It decreases the effectiveness of insecticides, thereby requiring greater quantities for comparable control with a net increase in risk of disease resurgence, product cost, and damage risk to the ecosystem. Pyrethroid resistance has been documented in Puerto Rican populations of Aedes aegypti (L.) mosquitoes. In this study, topical toxicity of five insecticides (permethrin, etofenprox, deltamethrin, DDT, transfluthrin) was determined for susceptible (Orlando—ORL) and resistant (Puerto Rico—PR) strains of Ae. aegypti. Resistance ratios were calculated using LD50 values, and high resistance ratios for permethrin (112) and etofenprox (228) were observed for the Puerto Rico strain. Behavioral differences in blood-feeding activity for pyrethroid-resistant and pyrethroid-susceptible strains of Ae. aegypti when exposed to pyrethroid-treated cloth were also explored. Strains were exposed for 15 min to a range of concentrations of pyrethroid-treated uniform fabric in a cage that contained 60 female Ae. aegypti mosquitoes. Interestingly, the resistance ratios for blood-feeding were similar for permethrin (61) and etofenprox (70), but were lower than their respective resistance ratios for topical toxicity, suggesting that knockdown resistance was the primary mechanism of resistance in the blood feeding assays. Results showed a rightward shift in the dose-response curves for blood-feeding that indicated higher concentrations of pyrethroids were necessary to deter blood-feeding behavior in the pyrethroid-resistant Puerto Rican strain of Ae. aegypti. PMID:28931018

Surface characterization protocol for precision aspheric optics

NASA Astrophysics Data System (ADS)

Sarepaka, RamaGopal V.; Sakthibalan, Siva; Doodala, Somaiah; Panwar, Rakesh S.; Kotaria, Rajendra

2017-10-01

In Advanced Optical Instrumentation, Aspherics provide an effective performance alternative. The aspheric fabrication and surface metrology, followed by aspheric design are complementary iterative processes for Precision Aspheric development. As in fabrication, a holistic approach of aspheric surface characterization is adopted to evaluate actual surface error and to aim at the deliverance of aspheric optics with desired surface quality. Precision optical surfaces are characterized by profilometry or by interferometry. Aspheric profiles are characterized by contact profilometers, through linear surface scans to analyze their Form, Figure and Finish errors. One must ensure that, the surface characterization procedure does not add to the resident profile errors (generated during the aspheric surface fabrication). This presentation examines the errors introduced post-surface generation and during profilometry of aspheric profiles. This effort is to identify sources of errors and is to optimize the metrology process. The sources of error during profilometry may be due to: profilometer settings, work-piece placement on the profilometer stage, selection of zenith/nadir points of aspheric profiles, metrology protocols, clear aperture - diameter analysis, computational limitations of the profiler and the software issues etc. At OPTICA, a PGI 1200 FTS contact profilometer (Taylor-Hobson make) is used for this study. Precision Optics of various profiles are studied, with due attention to possible sources of errors during characterization, with multi-directional scan approach for uniformity and repeatability of error estimation. This study provides an insight of aspheric surface characterization and helps in optimal aspheric surface production methodology.

The fabrication of flip-covered plasmonic nanostructure surfaces with enhanced wear resistance

NASA Astrophysics Data System (ADS)

Jung, Joo-Yun; Sung, Sang-Keun; Kim, Kwang-Seop; Cheon, So-Hui; Lee, Jihye; Choi, Jun-Hyuk; Lee, Eungsug

2017-01-01

Exposed nanostructure surfaces often suffer from external dynamic wear, particularly when used in human interaction, resulting in surface defects and the degradation of plasmonic resonance properties particularly in terms of transmittance extinction rate and peak-to-valley slope. In this work, a method for the fabrication of flip-covered silver nanostructure-arrayed surfaces is shown to enhance wear resistance. Selectively transferred silver dot and silver webbed-trench exposed reference samples were fabricated by metal nanoimprint, and flip-covered samples were created by flipping and bonding reference samples onto a PET film coated with an adhesive layer. The samples' spectral transmittance was measured before and after a dynamic wear test. Some spectral shift was observed due to the change in refractive index of the surrounding media, but this was not as significant as the effects of the other chosen geometry factors. It was found that dynamic wear had a greater effect on the plasmonic resonance behavior of the exposed samples than in those that had been flip-covered. This suggests that flip-covering may be an effective strategy for the protection of plasmonic resonators against dynamic wear. It is expected that the slight variations in spectral transmittance could be compensated through proper tuning of the sample geometry.

Design and fabrication of a low-cost Darrieus vertical-axis wind-turbine system, phase 2. Volume 3: Design, fabrication, and site drawing

NASA Astrophysics Data System (ADS)

1983-03-01

The design, fabrication, and site drawings associated with fabrication, installation, and check out of 100 kW 17 meter Vertical Axis Wind Turbines (VAWTs) were reported. The turbines are Darrieus type VAWTs with rotors 17 meters in diameter and 25.15 meters in height. They can produce 100 kW of electric power at a cost of energy as low as 3 cents per kWh, in an 18 mph wind regime using 12% annualized costs. Four turbines are produced, three are installed and operable.

MiniDSS: a low-power and high-precision miniaturized digital sun sensor

NASA Astrophysics Data System (ADS)

de Boer, B. M.; Durkut, M.; Laan, E.; Hakkesteegt, H.; Theuwissen, A.; Xie, N.; Leijtens, J. L.; Urquijo, E.; Bruins, P.

2017-11-01

A high-precision and low-power miniaturized digital sun sensor has been developed at TNO. The single-chip sun sensor comprises an application specific integrated circuit (ASIC) on which an active pixel sensor (APS), read-out and processing circuitry as well as communication circuitry are combined. The design was optimized for low recurrent cost. The sensor is albedo insensitive and the prototype combines an accuracy in the order of 0.03° with a mass of just 72 g and a power consumption of only 65 mW.

Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

NASA Astrophysics Data System (ADS)

Xia, Peng; Li, Luman; Wang, Pengfei; Gan, Ying; Xu, Wei

2017-11-01

A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM) Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF) state to low resistance (ON) state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

Studies of electrical properties of low-resistivity sandstones based on digital rock technology

NASA Astrophysics Data System (ADS)

Yan, Weichao; Sun, Jianmeng; Zhang, Jinyan; Yuan, Weiguo; Zhang, Li; Cui, Likai; Dong, Huaimin

2018-02-01

Electrical properties are important parameters to quantitatively calculate water saturation in oil and gas reservoirs by well logging interpretation. It is usual that oil layers show high resistivity responses, while water layers show low-resistivity responses. However, there are low-resistivity oil zones that exist in many oilfields around the world, leading to difficulties for reservoir evaluation. In our research, we used digital rock technology to study different internal and external factors to account for low rock resistivity responses in oil layers. We first constructed three-dimensional digital rock models with five components based on micro-computed tomography technology and x-ray diffraction experimental results, and then oil and water distributions in pores were determined by the pore morphology method. When the resistivity of each component was assigned, rock resistivities were calculated by using the finite element method. We collected 20 sandstone samples to prove the effectiveness of our numerical simulation methods. Based on the control variate method, we studied the effects of different factors on the resistivity indexes and rock resistivities. After sensitivity analyses, we found the main factors which caused low rock resistivities in oil layers. For unfractured rocks, influential factors arranged in descending order of importance were porosity, clay content, temperature, water salinity, heavy mineral, clay type and wettability. In addition, we found that the resistivity index could not provide enough information to identify a low-resistivity oil zone by using laboratory rock-electric experimental results. These results can not only expand our understandings of the electrical properties of low-resistivity rocks from oil layers, but also help identify low-resistivity oil zones better.

Active-passive hybrid piezoelectric actuators for high-precision hard disk drive servo systems

NASA Astrophysics Data System (ADS)

Chan, Kwong Wah; Liao, Wei-Hsin

2006-03-01

Positioning precision is crucial to today's increasingly high-speed, high-capacity, high data density, and miniaturized hard disk drives (HDDs). The demand for higher bandwidth servo systems that can quickly and precisely position the read/write head on a high track density becomes more pressing. Recently, the idea of applying dual-stage actuators to track servo systems has been studied. The push-pull piezoelectric actuated devices have been developed as micro actuators for fine and fast positioning, while the voice coil motor functions as a large but coarse seeking. However, the current dual-stage actuator design uses piezoelectric patches only without passive damping. In this paper, we propose a dual-stage servo system using enhanced active-passive hybrid piezoelectric actuators. The proposed actuators will improve the existing dual-stage actuators for higher precision and shock resistance, due to the incorporation of passive damping in the design. We aim to develop this hybrid servo system not only to increase speed of track seeking but also to improve precision of track following servos in HDDs. New piezoelectrically actuated suspensions with passive damping have been designed and fabricated. In order to evaluate positioning and track following performances for the dual-stage track servo systems, experimental efforts are carried out to implement the synthesized active-passive suspension structure with enhanced piezoelectric actuators using a composite nonlinear feedback controller.

Metallization of Self-Assembled DNA Templates for Electronic Circuit Fabrication

NASA Astrophysics Data System (ADS)

Uprety, Bibek

This work examines the deposition of metallic and semiconductor elements onto self-assembled DNA templates for the fabrication of nanodevices. Biological molecules like DNA self-assemble into a variety of 2- and 3-D architectures without the need for patterning tools. The templates can also be designed to controllably place functional nanomaterials with molecular precision. These characteristics make DNA an attractive template for fabricating electronic circuits. However, electrically conductive structures are needed for electronic applications. While metallized DNA nanostructures have been demonstrated, the ability to make thin, continuous wires that are electrically conductive still represents a formidable challenge. DNA-templated wires have generally been granular in appearance with a resistivity approximately two to three orders of magnitude higher than that of the bulk material. An improved method for the metallization of DNA origami is examined in this work that addresses these challenges of size, morphology and conductivity of the metallized structure. Specifically, we demonstrated a metallization process that uses gold nanorod seeds followed by anisotropic electroless (autocatalytic) plating to provide improved morphology and greater control of the final metallized width of conducting metal lines. Growth during electroless deposition occurs preferentially in the length direction at a rate that is approximately four times the growth rate in the width direction, which enables fabrication of narrow, continuous wires. The electrical properties of 49 nanowires with widths ranging from 13 nm to 29 nm were characterized, and resistivity values as low as 8.9 x 10-7 -m were measured, which represent some of the smallest nanowires and the lowest resistivity values reported in the literature. The metallization procedure developed on smaller templates was also successfully applied to metallize bigger DNA templates of tens of micrometers in length. In addition, a

Fabrication of durable super-repellent surfaces on cotton fabric with liquids of varying surface tension: Low surface energy and high roughness

NASA Astrophysics Data System (ADS)

Singh, Arun K.; Singh, Jayant K.

2017-09-01

In this study, we have developed super-repellent surface on cotton fabric via a facile and eco-friendly strategy using zirconia particles with water-soluble siloxane emulsion. The coated fabric using zirconia-siloxane (ZS) coating showed super-repellency of liquids with surface tension >47.7 mN/m, like water, mixtures of isopropyl alcohol with deionized water (2% and 5%, v/v), and ethylene glycol with contact angle of 158°, 155°, 153° and 152°, respectively. Furthermore, the coated fabric displays low sliding angle, <10°, with these liquids. The super-repellency of the coated fabric is attributed due to its lower surface energy (<1.0 mJ m-2). The produced coating exhibited excellent durability and retained its super-repelling properties under harsh environment conditions like acidic, alkaline, salty, ultraviolet irradiation, mechanical abrasion and repeated tear test with an adhesive tape. In addition, in a mixture of water and oil (having surface tension <30 mN/m), the developed coated fabric exhibited dual nature viz., superhydrophobicity and superoleophilicity, maintaining the super-repellency with water even they are wetted with oily liquids. The materials with ability to repel water in the presence of oily pollutants are very useful in application related to sea water. Thus as-prepared coated fabric, with dual functionality, is a promising material for many applications including anti-wetting, self-cleaning, support for aquatic floating devices and as a filtration material for rapid and continuous oil-water separation.

Evolution of high-level resistance during low-level antibiotic exposure.

PubMed

Wistrand-Yuen, Erik; Knopp, Michael; Hjort, Karin; Koskiniemi, Sanna; Berg, Otto G; Andersson, Dan I

2018-04-23

It has become increasingly clear that low levels of antibiotics present in many environments can select for resistant bacteria, yet the evolutionary pathways for resistance development during exposure to low amounts of antibiotics remain poorly defined. Here we show that Salmonella enterica exposed to sub-MIC levels of streptomycin evolved high-level resistance via novel mechanisms that are different from those observed during lethal selections. During lethal selection only rpsL mutations are found, whereas at sub-MIC selection resistance is generated by several small-effect resistance mutations that combined confer high-level resistance via three different mechanisms: (i) alteration of the ribosomal RNA target (gidB mutations), (ii) reduction in aminoglycoside uptake (cyoB, nuoG, and trkH mutations), and (iii) induction of the aminoglycoside-modifying enzyme AadA (znuA mutations). These results demonstrate how the strength of the selective pressure influences evolutionary trajectories and that even weak selective pressures can cause evolution of high-level resistance.

Method of high precision interval measurement in pulse laser ranging system

NASA Astrophysics Data System (ADS)

Wang, Zhen; Lv, Xin-yuan; Mao, Jin-jin; Liu, Wei; Yang, Dong

2013-09-01

Laser ranging is suitable for laser system, for it has the advantage of high measuring precision, fast measuring speed,no cooperative targets and strong resistance to electromagnetic interference,the measuremen of laser ranging is the key paremeters affecting the performance of the whole system.The precision of the pulsed laser ranging system was decided by the precision of the time interval measurement, the principle structure of laser ranging system was introduced, and a method of high precision time interval measurement in pulse laser ranging system was established in this paper.Based on the analysis of the factors which affected the precision of range measure,the pulse rising edges discriminator was adopted to produce timing mark for the start-stop time discrimination,and the TDC-GP2 high precision interval measurement system based on TMS320F2812 DSP was designed to improve the measurement precision.Experimental results indicate that the time interval measurement method in this paper can obtain higher range accuracy. Compared with the traditional time interval measurement system,the method simplifies the system design and reduce the influence of bad weather conditions,furthermore,it satisfies the requirements of low costs and miniaturization.

Integration of radar altimeter, precision navigation, and digital terrain data for low-altitude flight

NASA Technical Reports Server (NTRS)

Zelenka, Richard E.

1992-01-01

Avionic systems that depend on digitized terrain elevation data for guidance generation or navigational reference require accurate absolute and relative distance measurements to the terrain, especially as they approach lower altitudes. This is particularly exacting in low-altitude helicopter missions, where aggressive terrain hugging maneuvers create minimal horizontal and vertical clearances and demand precise terrain positioning. Sole reliance on airborne precision navigation and stored terrain elevation data for above-ground-level (AGL) positioning severely limits the operational altitude of such systems. A Kalman filter is presented which blends radar altimeter returns, precision navigation, and stored terrain elevation data for AGL positioning. The filter is evaluated using low-altitude helicopter flight test data acquired over moderately rugged terrain. The proposed Kalman filter is found to remove large disparities in predicted AGL altitude (i.e., from airborne navigation and terrain elevation data) in the presence of measurement anomalies and dropouts. Previous work suggested a minimum clearance altitude of 220 ft AGL for a near-terrain guidance system; integration of a radar altimeter allows for operation of that system below 50 ft, subject to obstacle-avoidance limitations.

Pressure measurements with a precision of 0.001 ppm in magnetic fields at low temperatures

NASA Astrophysics Data System (ADS)

Miura, Y.; Matsushima, N.; Ando, T.; Kuno, S.; Inoue, S.; Ito, K.; Mamiya, T.

1993-11-01

Pressure measurements made by an ac bridge technique with a precision of 0.001 ppm in magnetic fields at low temperatures using a Straty-Adams type gauge are described. In order to improve the sensitivity and the long-term stability of the bridge system, coaxial cables without dielectric insulator were developed, with a small cable capacitance temperature coefficient of the impedance. This pressure measurement system has a sensitivity of dP/P˜5×10-10 and a long-term stability of dP/P˜2.4×10-9 over 18 h. This is especially useful for measurements such as electric and magnetic susceptibility measurements in magnetic fields at low temperatures requiring a high precision.

Precision medicine for advanced prostate cancer.

PubMed

Mullane, Stephanie A; Van Allen, Eliezer M

2016-05-01

Precision cancer medicine, the use of genomic profiling of patient tumors at the point-of-care to inform treatment decisions, is rapidly changing treatment strategies across cancer types. Precision medicine for advanced prostate cancer may identify new treatment strategies and change clinical practice. In this review, we discuss the potential and challenges of precision medicine in advanced prostate cancer. Although primary prostate cancers do not harbor highly recurrent targetable genomic alterations, recent reports on the genomics of metastatic castration-resistant prostate cancer has shown multiple targetable alterations in castration-resistant prostate cancer metastatic biopsies. Therapeutic implications include targeting prevalent DNA repair pathway alterations with PARP-1 inhibition in genomically defined subsets of patients, among other genomically stratified targets. In addition, multiple recent efforts have demonstrated the promise of liquid tumor profiling (e.g., profiling circulating tumor cells or cell-free tumor DNA) and highlighted the necessary steps to scale these approaches in prostate cancer. Although still in the initial phase of precision medicine for prostate cancer, there is extraordinary potential for clinical impact. Efforts to overcome current scientific and clinical barriers will enable widespread use of precision medicine approaches for advanced prostate cancer patients.

Micro-Thermoelectric Generation Modules Fabricated with Low-Cost Mechanical Machining Processes

NASA Astrophysics Data System (ADS)

Liu, Dawei; Jin, A. J.; Peng, Wenbo; Li, Qiming; Gao, Hu; Zhu, Lianjun; Li, Fu; Zhu, Zhixiang

2017-05-01

Micro/small-scale thermoelectric generation modules are able to produce continuous, noise-free and reliable electricity power using low temperature differences that widely exist in nature or industry. These advantages bring them great application prospects in the fields of remote monitoring, microelectronics/micro-electromechanical systems (MEMS), medical apparatus and smart management system, which often require a power source free of maintenance and vibration. In this work, a prototypical thermoelectric module (12 mm × 12 mm × 0.8 mm) with 15 pairs of micro-scale thermoelectric legs (0.2 mm in width and 0.6 mm in height for each leg) is fabricated using a low-cost mechanical machining process. In this process, cutting and polishing are the main methods for the preparation of thermoelectric pairs from commercial polycrystalline materials and for the fabrication of electrode patterns. The as-fabricated module is tested for its power generation properties with the hot side heated by an electrical heater and the cold side by cold air. With the heater temperature of 375 K, the thermoelectric potential is about 9.1 mV, the short circuit current is about 14.5 mA, and the maximum output power is about 32.8 μW. The finite element method is applied to analyze the heat transfer of the module during our test. The temperature difference and heat flux are simulated, according to which the output powers at different temperatures are calculated, and the result is relatively consistent compared to the test results.

Manufacturing Precise, Lightweight Paraboloidal Mirrors

NASA Technical Reports Server (NTRS)

Hermann, Frederick Thomas

2006-01-01

A process for fabricating a precise, diffraction- limited, ultra-lightweight, composite- material (matrix/fiber) paraboloidal telescope mirror has been devised. Unlike the traditional process of fabrication of heavier glass-based mirrors, this process involves a minimum of manual steps and subjective judgment. Instead, this process involves objectively controllable, repeatable steps; hence, this process is better suited for mass production. Other processes that have been investigated for fabrication of precise composite-material lightweight mirrors have resulted in print-through of fiber patterns onto reflecting surfaces, and have not provided adequate structural support for maintenance of stable, diffraction-limited surface figures. In contrast, this process does not result in print-through of the fiber pattern onto the reflecting surface and does provide a lightweight, rigid structure capable of maintaining a diffraction-limited surface figure in the face of changing temperature, humidity, and air pressure. The process consists mainly of the following steps: 1. A precise glass mandrel is fabricated by conventional optical grinding and polishing. 2. The mandrel is coated with a release agent and covered with layers of a carbon- fiber composite material. 3. The outer surface of the outer layer of the carbon-fiber composite material is coated with a surfactant chosen to provide for the proper flow of an epoxy resin to be applied subsequently. 4. The mandrel as thus covered is mounted on a temperature-controlled spin table. 5. The table is heated to a suitable temperature and spun at a suitable speed as the epoxy resin is poured onto the coated carbon-fiber composite material. 6. The surface figure of the optic is monitored and adjusted by use of traditional Ronchi, Focault, and interferometric optical measurement techniques while the speed of rotation and the temperature are adjusted to obtain the desired figure. The proper selection of surfactant, speed or rotation

Fracture toughness study on LIGA fabricated microstructures

NASA Astrophysics Data System (ADS)

Oropeza, Catherine; Lian, Kun; Wang, Wanjun

2003-01-01

One of the major difficulties faced by MEMS researchers today is the lack of data regarding properties of electroplated metals or alloys at micro-levels as those produced by the LIGA and the LIGA related process. These mechanical properties are not well known and they cannot be extrapolated from macro-scale data without experimental verification. This lack of technical information about physical properties at microscale has affected the consistency and reliability of batch-fabricated components and leads to very low rates of successful fabrication. Therefore, this material issue is of vital importance to the development of LIGA technology and to its industrial applications. The research work reported in this paper focuses on the development of a new capability based on design, fabrication, and testing of groups of UV-LIGA fabricated nickel microspecimens for the evaluation of fracture strength. The devised testing mechanism demonstrated compatibility with the fabricated samples and capability of performing the desired experimentation by generating resistance-to-fracture values of the nickel specimens. The average fracture strength value obtained, expressed with a 95% confidence interval, was 315 +/- 54 Mpa. Further data acquisition, especially involving tensile specimen testing, and material analysis is needed to fully understand the implications of the information obtained.

Steady-state low thermal resistance characterization apparatus: The bulk thermal tester

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burg, Brian R.; Kolly, Manuel; Blasakis, Nicolas

The reliability of microelectronic devices is largely dependent on electronic packaging, which includes heat removal. The appropriate packaging design therefore necessitates precise knowledge of the relevant material properties, including thermal resistance and thermal conductivity. Thin materials and high conductivity layers make their thermal characterization challenging. A steady state measurement technique is presented and evaluated with the purpose to characterize samples with a thermal resistance below 100 mm{sup 2} K/W. It is based on the heat flow meter bar approach made up by two copper blocks and relies exclusively on temperature measurements from thermocouples. The importance of thermocouple calibration is emphasizedmore » in order to obtain accurate temperature readings. An in depth error analysis, based on Gaussian error propagation, is carried out. An error sensitivity analysis highlights the importance of the precise knowledge of the thermal interface materials required for the measurements. Reference measurements on Mo samples reveal a measurement uncertainty in the range of 5% and most accurate measurements are obtained at high heat fluxes. Measurement techniques for homogeneous bulk samples, layered materials, and protruding cavity samples are discussed. Ultimately, a comprehensive overview of a steady state thermal characterization technique is provided, evaluating the accuracy of sample measurements with thermal resistances well below state of the art setups. Accurate characterization of materials used in heat removal applications, such as electronic packaging, will enable more efficient designs and ultimately contribute to energy savings.« less

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Low Temperature Resistive Switching Behavior in a Manganite

NASA Astrophysics Data System (ADS)

Salvo, Christopher; Lopez, Melinda; Tsui, Stephen

2012-02-01

The development of new nonvolatile memory devices remains an important field of consumer electronics. A possible candidate is bipolar resistive switching, a method by which the resistance of a material changes when a voltage is applied. Although there is a great deal of research on this topic, not much has been done at low temperatures. In this work, we compare the room temperature and low temperature behaviors of switching in a manganite thin film. The data indicates that the switching is suppressed upon cooling to cryogenic temperatures, and the presence of crystalline charge traps is tied to the physical mechanism.

Miniature Scroll Pumps Fabricated by LIGA

NASA Technical Reports Server (NTRS)

Wiberg, Dean; Shcheglov, Kirill; White, Victor; Bae, Sam

2009-01-01

Miniature scroll pumps have been proposed as roughing pumps (low - vacuum pumps) for miniature scientific instruments (e.g., portable mass spectrometers and gas analyzers) that depend on vacuum. The larger scroll pumps used as roughing pumps in some older vacuum systems are fabricated by conventional machining. Typically, such an older scroll pump includes (1) an electric motor with an eccentric shaft to generate orbital motion of a scroll and (2) conventional bearings to restrict the orbital motion to a circle. The proposed miniature scroll pumps would differ from the prior, larger ones in both design and fabrication. A miniature scroll pump would include two scrolls: one mounted on a stationary baseplate and one on a flexure stage (see figure). An electromagnetic actuator in the form of two pairs of voice coils in a push-pull configuration would make the flexure stage move in the desired circular orbit. The capacitance between the scrolls would be monitored to provide position (gap) feedback to a control system that would adjust the drive signals applied to the voice coils to maintain the circular orbit as needed for precise sealing of the scrolls. To minimize power consumption and maximize precision of control, the flexure stage would be driven at the frequency of its mechanical resonance. The miniaturization of these pumps would entail both operational and manufacturing tolerances of <1 m. Such tight tolerances cannot be achieved easily by conventional machining of high-aspect-ratio structures like those of scroll-pump components. In addition, the vibrations of conventional motors and ball bearings exceed these tight tolerances by an order of magnitude. Therefore, the proposed pumps would be fabricated by the microfabrication method known by the German acronym LIGA ( lithographie, galvanoformung, abformung, which means lithography, electroforming, molding) because LIGA has been shown to be capable of providing the required tolerances at large aspect ratios.

Fabrication and testing of fire resistant graphite composite panels

NASA Technical Reports Server (NTRS)

Roper, W. D.

1986-01-01

Eight different graphite composite panels were fabricated using four different resin matrices. The resin matrices included Hercules 71775, a blend of vinylpolystyrpyridine and bismaleimide, H795, a bismaleimide, Cycom 6162, a phenolic, and PSP 6022m, a polystyrylpyridine. Graphite panels were fabricated using fabric or unidirectional tape. Described are the processes for preparing these panels and some of their mechanical, thermal and flammability properties. Panel properties are compared with state-of-the-art epoxy fiberglass composite panels.

Facile Fabrication of a Polyethylene Mesh for Oil/Water Separation in a Complex Environment.

PubMed

Zhao, Tianyi; Zhang, Dongmei; Yu, Cunming; Jiang, Lei

2016-09-14

Low cost, eco-friendly, and easily scaled-up processes are needed to fabricate efficient oil/water separation materials, especially those useful in harsh environments such as highly acidic, alkaline, and salty environments, to deal with serious oil spills and industrial organic pollutants. Herein, a highly efficient oil/water separation mesh with durable chemical stability was fabricated by simply scratching and pricking a conventional polyethylene (PE) film. Multiscaled morphologies were obtained by this scratching and pricking process and provided the mesh with a special wettability performance termed superhydrophobicity, superoleophilicity, and low water adhesion, while the inert chemical properties of PE delivered chemical etching resistance to the fabricated mesh. In addition to a highly efficient oil/corrosive liquid separation, the fabricated PE mesh was also reusable and exhibited ultrafast oil/water separation solely by gravity. The easy operation, chemical durability, reusability, and efficiency of the novel PE mesh give it high potential for use in industrial and consumer applications.

Ultra precision machining

NASA Astrophysics Data System (ADS)

Debra, Daniel B.; Hesselink, Lambertus; Binford, Thomas

1990-05-01

There are a number of fields that require or can use to advantage very high precision in machining. For example, further development of high energy lasers and x ray astronomy depend critically on the manufacture of light weight reflecting metal optical components. To fabricate these optical components with machine tools they will be made of metal with mirror quality surface finish. By mirror quality surface finish, it is meant that the dimensions tolerances on the order of 0.02 microns and surface roughness of 0.07. These accuracy targets fall in the category of ultra precision machining. They cannot be achieved by a simple extension of conventional machining processes and techniques. They require single crystal diamond tools, special attention to vibration isolation, special isolation of machine metrology, and on line correction of imperfection in the motion of the machine carriages on their way.

R&D 100, 2016: Stress-Induced Fabrication

ScienceCinema

Fan, Hongyou; Brennan, Tom; Wise, Jack; Liu, Sheng; Hickman, Randy

2018-06-13

Stress-induced fabrication (SIF) uses compressive mechanical stress to create new nanomaterials with lower production costs and enhanced materials performance compared to traditional fabrication routes. Simple, innovative, and with more degrees of freedom than current chemical synthesis methods, SIF uses physical force instead of chemistry applied to form new nanomaterials with precisely controlled structure and tunable properties.

R&D 100, 2016: Stress-Induced Fabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Hongyou; Brennan, Tom; Wise, Jack

Stress-induced fabrication (SIF) uses compressive mechanical stress to create new nanomaterials with lower production costs and enhanced materials performance compared to traditional fabrication routes. Simple, innovative, and with more degrees of freedom than current chemical synthesis methods, SIF uses physical force instead of chemistry applied to form new nanomaterials with precisely controlled structure and tunable properties.

Design and fabrication of conventional and unconventional superconductors

NASA Technical Reports Server (NTRS)

Collings, E. W.

1983-01-01

The design and fabrication of conventional and unconventionally processed Ti-Nb base and Al5-compound-base, respectively, composite superconductors is discussed in a nine section review. The first two sections introduce the general properties of alloy and compound superconductors, and the design and processing requirements for the production of long lengths of stable low loss conductor. All aspects of flux jump stability, and the general requirements of cryogenic stabilization are addressed. Conductor design from an a.c.-loss standpoint; some basic formulae describing hysteretic and eddy current losses and the influences on a.c. loss of filament diameter, strand (conductor) diameter, twist pitch, and matrix resistivity are discussed. The basic techniques used in the fabrication of conventional multifilamentary conductors are described.

Low resistivity ZnO-GO electron transport layer based CH{sub 3}NH{sub 3}PbI{sub 3} solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, Muhammad Imran, E-mail: imranrahbar@scme.nust.edu.pk, E-mail: amirhabib@scme.nust.edu.pk; Hussain, Zakir; Mujahid, Mohammad

Perovskite based solar cells have demonstrated impressive performances. Controlled environment synthesis and expensive hole transport material impede their potential commercialization. We report ambient air synthesis of hole transport layer free devices using ZnO-GO as electron selective contacts. Solar cells fabricated with hole transport layer free architecture under ambient air conditions with ZnO as electron selective contact achieved an efficiency of 3.02%. We have demonstrated that by incorporating GO in ZnO matrix, low resistivity electron selective contacts, critical to improve the performance, can be achieved. We could achieve max efficiency of 4.52% with our completed devices for ZnO: GO composite. Impedancemore » spectroscopy confirmed the decrease in series resistance and an increase in recombination resistance with inclusion of GO in ZnO matrix. Effect of temperature on completed devices was investigated by recording impedance spectra at 40 and 60 {sup o}C, providing indirect evidence of the performance of solar cells at elevated temperatures.« less

A low-cost, high-yield fabrication method for producing optimized biomimetic dry adhesives

NASA Astrophysics Data System (ADS)

Sameoto, D.; Menon, C.

2009-11-01

We present a low-cost, large-scale method of fabricating biomimetic dry adhesives. This process is useful because it uses all photosensitive polymers with minimum fabrication costs or complexity to produce molds for silicone-based dry adhesives. A thick-film lift-off process is used to define molds using AZ 9260 photoresist, with a slow acting, deep UV sensitive material, PMGI, used as both an adhesion promoter for the AZ 9260 photoresist and as an undercutting material to produce mushroom-shaped fibers. The benefits to this process are ease of fabrication, wide range of potential layer thicknesses, no special surface treatment requirements to demold silicone adhesives and easy stripping of the full mold if process failure does occur. Sylgard® 184 silicone is used to cast full sheets of biomimetic dry adhesives off 4" diameter wafers, and different fiber geometries are tested for normal adhesion properties. Additionally, failure modes of the adhesive during fabrication are noted and strategies for avoiding these failures are discussed. We use this fabrication method to produce different fiber geometries with varying cap diameters and test them for normal adhesion strengths. The results indicate that the cap diameters relative to post diameters for mushroom-shaped fibers dominate the adhesion properties.

Plasmonic nanoparticle lithography: Fast resist-free laser technique for large-scale sub-50 nm hole array fabrication

NASA Astrophysics Data System (ADS)

Pan, Zhenying; Yu, Ye Feng; Valuckas, Vytautas; Yap, Sherry L. K.; Vienne, Guillaume G.; Kuznetsov, Arseniy I.

2018-05-01

Cheap large-scale fabrication of ordered nanostructures is important for multiple applications in photonics and biomedicine including optical filters, solar cells, plasmonic biosensors, and DNA sequencing. Existing methods are either expensive or have strict limitations on the feature size and fabrication complexity. Here, we present a laser-based technique, plasmonic nanoparticle lithography, which is capable of rapid fabrication of large-scale arrays of sub-50 nm holes on various substrates. It is based on near-field enhancement and melting induced under ordered arrays of plasmonic nanoparticles, which are brought into contact or in close proximity to a desired material and acting as optical near-field lenses. The nanoparticles are arranged in ordered patterns on a flexible substrate and can be attached and removed from the patterned sample surface. At optimized laser fluence, the nanohole patterning process does not create any observable changes to the nanoparticles and they have been applied multiple times as reusable near-field masks. This resist-free nanolithography technique provides a simple and cheap solution for large-scale nanofabrication.

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

1995-05-09

A high performance capacitor is fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a ``notepad`` configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The notepad capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density. 5 figs.

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

1996-01-23

A high performance capacitor is described which is fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a ``notepad`` configuration composed of 200--300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The ``notepad`` capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density. 5 figs.

Low-frequency dielectric spectra of low-resistivity GaSe crystals (in Ukrainian)

NASA Astrophysics Data System (ADS)

Stakhira, J.; Fl'Unt, O.; Fiyala, Ya.

The low-frequency dielectric response of low-resistivity GaSe layered crystal along the c-axis has been investigated at liquid nitrogen temperatures. The normalized spectra (activation energies from frequency shift is 0.19 eV) have been treated analytically employing equivalent circuits. It is shown that experimental data cannot be obtained with the circuit containing only ideal capacitors and resistors. At the same time, the equivalent circuit containing dispersive capacitors characterized by the power law dependence on frequency C^*=B(jω)^{n-1}, where ω is radian frequency, 0< n< 1, gives a good agreement with experimental data. This means that measured response of low-resistivity GaSe crystals follows the ``universal" power law of dielectric response χ^*˜(jω)^{n-1}, but not the Debye one. The nature of the ``universal" power law is explained by many-body interactions between localized charge carriers.

Potassium-argon (argon-argon), structural fabrics

USGS Publications Warehouse

Cosca, Michael A.; Rink, W. Jack; Thompson, Jereon

2014-01-01

Definition: 40Ar/39Ar geochronology of structural fabrics: The application of 40Ar/39Ar methods to date development of structural fabrics in geologic samples. Introduction: Structural fabrics develop during rock deformation at variable pressures (P), temperatures (T), fluid compositions (X), and time (t). Structural fabrics are represented in rocks by features such as foliations and shear zones developed at the mm to km scale. In ideal cases, the P-T-X history of a given structural fabric can be constrained using stable isotope, cation exchange, and/or mineral equilibria thermobarometry (Essene 1989). The timing of structural fabric development can be assessed qualitatively using geologic field observations or quantitatively using isotope-based geochronology. High-precision geochronology of the thermal and fluid flow histories associated with structural fabric development can answer fundamental geologic questions including (1) when hydrothermal fluids transported and deposited ore minerals, ...

Preliminary Results on New Prototypes of Precision Rh-0.5at%Fe Resistance Thermometers of Chinese Production

NASA Astrophysics Data System (ADS)

Pavese, F.; Szmyrka-Grzebyk, A.; Lipinski, L.; Manuszkiewicz, H.; Qiu, Ping; Zhang, Jin Tao; Lin, Peng; Li, Xing Wei

2008-02-01

Given the practical impossibility of obtaining new precision Rh-0.5at%Fe resistance thermometers in recent years, the possible re-starting of the production of such thermometers in Yunnan (China) was explored by Istituto Nazionale di Ricerca Metrologica (INRIM). Ten prototypes of the new production were made available in early 2006. The paper reports the preliminary data from the testing performed to date on these prototypes at National Institute of Metrology (NIM) and Instytut Niskich Temperatur i Badan Strukturalnych (INTiBS). Although a problem with the alloy composition was detected, the reproducibility results on thermal cycling are very encouraging. Resistance-temperature ( R- T) characteristics below 30 K, though not identical with those of similar thermometers formerly available from Tinsley and VNIIFTRI, are still suitable for accurate metrology.

Low-cost CWDM transmitter package

NASA Astrophysics Data System (ADS)

Bhandarkar, Navin; Castillega, Jaime

2005-03-01

A low-cost coarse-wavelength-division multiplexer (CWDM) transmitter that combines four channels (wavelengths) in the infrared spectrum (~1310 nm) in a small form-factor un-cooled package is demonstrated. The package utilizes precision molded optics to multiplex beams from four grating-outcoupled surface-emitting (GSE) lasers into a single beam suitable for coupling into multimode fiber. This paper summarizes the optical and opto-mechanical design, fabrication and assembly of prototypes, and optical, thermal and electrical measurement results of the prototypes. This unique design enables multiplexing of wavelengths without the use of filters, waveguides, couplers and fiber splicing. Commercial fabrication and alignment technology is used to manufacture the package, resulting in a more robust, reliable and low-cost transmitter. The transmitter package is enabled by the unique characteristics of the long-wavelength GSE laser.

Fabrication of diamond based sensors for use in extreme environments

DOE PAGES

Samudrala, Gopi K.; Moore, Samuel L.; Vohra, Yogesh K.

2015-04-23

Electrical and magnetic sensors can be lithographically fabricated on top of diamond substrates and encapsulated in a protective layer of chemical vapor deposited single crystalline diamond. This process when carried out on single crystal diamond anvils employed in high pressure research is termed as designer diamond anvil fabrication. These designer diamond anvils allow researchers to study electrical and magnetic properties of materials under extreme conditions without any possibility of damaging the sensing elements. We describe a novel method for the fabrication of designer diamond anvils with the use of maskless lithography and chemical vapor deposition in this paper. This methodmore » can be utilized to produce diamond based sensors which can function in extreme environments of high pressures, high and low temperatures, corrosive and high radiation conditions. Here, we demonstrate applicability of these diamonds under extreme environments by performing electrical resistance measurements during superconducting transition in rare earth doped iron-based compounds under high pressures to 12 GPa and low temperatures to 10 K.« less

Fabrication of diamond based sensors for use in extreme environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samudrala, Gopi K.; Moore, Samuel L.; Vohra, Yogesh K.

Electrical and magnetic sensors can be lithographically fabricated on top of diamond substrates and encapsulated in a protective layer of chemical vapor deposited single crystalline diamond. This process when carried out on single crystal diamond anvils employed in high pressure research is termed as designer diamond anvil fabrication. These designer diamond anvils allow researchers to study electrical and magnetic properties of materials under extreme conditions without any possibility of damaging the sensing elements. We describe a novel method for the fabrication of designer diamond anvils with the use of maskless lithography and chemical vapor deposition in this paper. This methodmore » can be utilized to produce diamond based sensors which can function in extreme environments of high pressures, high and low temperatures, corrosive and high radiation conditions. Here, we demonstrate applicability of these diamonds under extreme environments by performing electrical resistance measurements during superconducting transition in rare earth doped iron-based compounds under high pressures to 12 GPa and low temperatures to 10 K.« less

Feasibility of precise navigation in high and low latitude regions under scintillation conditions

NASA Astrophysics Data System (ADS)

Juan, José Miguel; Sanz, Jaume; González-Casado, Guillermo; Rovira-Garcia, Adrià; Camps, Adriano; Riba, Jaume; Barbosa, José; Blanch, Estefania; Altadill, David; Orus, Raul

2018-02-01

Scintillation is one of the most challenging problems in Global Navigation Satellite Systems (GNSS) navigation. This phenomenon appears when the radio signal passes through ionospheric irregularities. These irregularities represent rapid changes on the refraction index and, depending on their size, they can produce also diffractive effects affecting the signal amplitude and, eventually producing cycle slips. In this work, we show that the scintillation effects on the GNSS signal are quite different in low and high latitudes. For low latitude receivers, the main effects, from the point of view of precise navigation, are the increase of the carrier phase noise (measured by σϕ) and the fade on the signal intensity (measured by S4) that can produce cycle slips in the GNSS signal. With several examples, we show that the detection of these cycle slips is the most challenging problem for precise navigation, in such a way that, if these cycle slips are detected, precise navigation can be achieved in these regions under scintillation conditions. For high-latitude receivers the situation differs. In this region the size of the irregularities is typically larger than the Fresnel length, so the main effects are related with the fast change on the refractive index associated to the fast movement of the irregularities (which can reach velocities up to several km/s). Consequently, the main effect on the GNSS signals is a fast fluctuation of the carrier phase (large σϕ), but with a moderate fade in the amplitude (moderate S4). Therefore, as shown through several examples, fluctuations at high-latitude usually do not produce cycle slips, being the effect quite limited on the ionosphere-free combination and, in general, precise navigation can be achieved also during strong scintillation conditions.

Low Cost, Net Shape Fabrication of Rhenium and High Temperature Materials for Rocket Engine Components

DTIC Science & Technology

2001-03-01

tungsten thin wall nozzle liner removed from reusable mandrel. b) W and Re rocket, nozzle inserts (2 inserts per mandrel) for Air Force. Rhenium PPI...compares the fabrication time for the VPS nozzles with equivalent carbon / carbon composite (C/C) and forged tungsten materials. Table 5: Comparison of...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO1 1181 TITLE: Low Cost, Net Shape Fabrication of Rhenium and High

SmallSat Precision Navigation with Low-Cost MEMS IMU Swarms

NASA Technical Reports Server (NTRS)

Christian, John; Bishop, Robert; Martinez, Andres; Petro, Andrew

2015-01-01

The continued advancement of small satellite-based science missions requires the solution to a number of important technical challenges. Of particular note is that small satellite missions are characterized by tight constraints on cost, mass, power, and volume that make them unable to fly the high-quality Inertial Measurement Units (IMUs) required for orbital missions demanding precise orientation and positioning. Instead, small satellite missions typically fly low-cost Micro-Electro-Mechanical System (MEMS) IMUs. Unfortunately, the performance characteristics of these MEMS IMUs make them ineffectual in many spaceflight applications when employed in a single IMU system configuration.

Low-Temperature Fabrication of Robust, Transparent, and Flexible Thin-Film Transistors with a Nanolaminated Insulator.

PubMed

Kwon, Jeong Hyun; Park, Junhong; Lee, Myung Keun; Park, Jeong Woo; Jeon, Yongmin; Shin, Jeong Bin; Nam, Minwoo; Kim, Choong-Ki; Choi, Yang-Kyu; Choi, Kyung Cheol

2018-05-09

The lack of reliable, transparent, and flexible electrodes and insulators for applications in thin-film transistors (TFTs) makes it difficult to commercialize transparent, flexible TFTs (TF-TFTs). More specifically, conventional high process temperatures and the brittleness of these elements have been hurdles in developing flexible substrates vulnerable to heat. Here, we propose electrode and insulator fabrication techniques considering process temperature, transmittance, flexibility, and environmental stability. A transparent and flexible indium tin oxide (ITO)/Ag/ITO (IAI) electrode and an Al 2 O 3 /MgO (AM)-laminated insulator were optimized at the low temperature of 70 °C for the fabrication of TF-TFTs on a polyethylene terephthalate (PET) substrate. The optimized IAI electrode with a sheet resistance of 7 Ω/sq exhibited the luminous transmittance of 85.17% and maintained its electrical conductivity after exposure to damp heat conditions because of an environmentally stable ITO capping layer. In addition, the electrical conductivity of IAI was maintained after 10 000 bending cycles with a tensile strain of 3% because of the ductile Ag film. In the metal/insulator/metal structure, the insulating and mechanical properties of the optimized AM-laminated film deposited at 70 °C were significantly improved because of the highly dense nanolaminate system, compared to those of the Al 2 O 3 film deposited at 70 °C. In addition, the amorphous indium-gallium-zinc oxide (a-IGZO) was used as the active channel for TF-TFTs because of its excellent chemical stability. In the environmental stability test, the ITO, a-IGZO, and AM-laminated films showed the excellent environmental stability. Therefore, our IGZO-based TFT with IAI electrodes and the 70 °C AM-laminated insulator was fabricated to evaluate robustness, transparency, flexibility, and process temperature, resulting in transfer characteristics comparable to those of an IGZO-based TFT with a 150 °C Al 2 O 3

On the toughness scatter in low alloy C-Mn steel samples fabricated using wire arc additive manufacturing

DOE PAGES

Sridharan, Niyanth S.; Noakes, Mark W.; Nycz, Andrzej; ...

2017-12-06

Low alloy carbon manganese (C-Mn) steel builds were fabricated using a wire based additive manufacturing system developed at Oak Ridge National Laboratory. Specimens were fabricated in the X,Y and Z direction and detailed mechanical testing was performed. The mechanical testing results showed a significant scatter in tensile ductility and significant variation in Charpy toughness. Further detailed microstructure characterization showed significant microstructural heterogeneity in builds fabricated in each direction. The scatter in mechanical properties was then rationalized based on the microstructural observations and the underlying changes in the local heat transfer conditions. Lastly, the results indicate that when fabricating parts usingmore » C-Mn low alloy steel welds the process parameters and tool path should be chosen such that the cooling rate from 800 °C to 500 °C is greater than 30 s to avoid formation of martensite austenite (MA) phases, which leads to toughness reductions.« less

On the toughness scatter in low alloy C-Mn steel samples fabricated using wire arc additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sridharan, Niyanth S.; Noakes, Mark W.; Nycz, Andrzej

Low alloy carbon manganese (C-Mn) steel builds were fabricated using a wire based additive manufacturing system developed at Oak Ridge National Laboratory. Specimens were fabricated in the X,Y and Z direction and detailed mechanical testing was performed. The mechanical testing results showed a significant scatter in tensile ductility and significant variation in Charpy toughness. Further detailed microstructure characterization showed significant microstructural heterogeneity in builds fabricated in each direction. The scatter in mechanical properties was then rationalized based on the microstructural observations and the underlying changes in the local heat transfer conditions. Lastly, the results indicate that when fabricating parts usingmore » C-Mn low alloy steel welds the process parameters and tool path should be chosen such that the cooling rate from 800 °C to 500 °C is greater than 30 s to avoid formation of martensite austenite (MA) phases, which leads to toughness reductions.« less

Powder metallurgy inspired low-temperature fabrication of high-performance stereocomplexed polylactide products with good optical transparency

NASA Astrophysics Data System (ADS)

Bai, Dongyu; Liu, Huili; Bai, Hongwei; Zhang, Qin; Fu, Qiang

2016-02-01

Stereocomplexation between enantiomeric poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) provides an avenue to greatly enhance performance of eco-friendly polylactide (PLA). Unfortunately, although the manufacturing of semicrystalline polymers generally involves melt processing, it is still hugely challenging to create high-performance stereocomplexed polylactide (sc-PLA) products from melt-processed high-molecular-weight PLLA/PDLA blends due to the weak crystallization memory effect of stereocomplex (sc) crystallites after complete melting as well as the substantial degradation of PLA chains at elevated melt-processing temperatures of ca. 240-260 °C. Inspired by the concept of powder metallurgy, here we report a new facile route to address these obstacles by sintering of sc-PLA powder at temperatures as low as 180-210 °C, which is distinctly different from traditional sintering of polymer powders performed at temperatures far exceeding their melting temperatures. The enantiomeric PLA chain segments from adjacent powder particles can interdiffuse across particle interfaces and co-crystallize into new sc crystallites capable of tightly welding the interfaces during the low-temperature sintering process, and thus highly transparent sc-PLA products with outstanding heat resistance, mechanical strength, and hydrolytic stability have been successfully fabricated for the first time.

Powder metallurgy inspired low-temperature fabrication of high-performance stereocomplexed polylactide products with good optical transparency

PubMed Central

Bai, Dongyu; Liu, Huili; Bai, Hongwei; Zhang, Qin; Fu, Qiang

2016-01-01

Stereocomplexation between enantiomeric poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) provides an avenue to greatly enhance performance of eco-friendly polylactide (PLA). Unfortunately, although the manufacturing of semicrystalline polymers generally involves melt processing, it is still hugely challenging to create high-performance stereocomplexed polylactide (sc-PLA) products from melt-processed high-molecular-weight PLLA/PDLA blends due to the weak crystallization memory effect of stereocomplex (sc) crystallites after complete melting as well as the substantial degradation of PLA chains at elevated melt-processing temperatures of ca. 240–260 °C. Inspired by the concept of powder metallurgy, here we report a new facile route to address these obstacles by sintering of sc-PLA powder at temperatures as low as 180–210 °C, which is distinctly different from traditional sintering of polymer powders performed at temperatures far exceeding their melting temperatures. The enantiomeric PLA chain segments from adjacent powder particles can interdiffuse across particle interfaces and co-crystallize into new sc crystallites capable of tightly welding the interfaces during the low-temperature sintering process, and thus highly transparent sc-PLA products with outstanding heat resistance, mechanical strength, and hydrolytic stability have been successfully fabricated for the first time. PMID:26837848

Powder metallurgy inspired low-temperature fabrication of high-performance stereocomplexed polylactide products with good optical transparency.

PubMed

Bai, Dongyu; Liu, Huili; Bai, Hongwei; Zhang, Qin; Fu, Qiang

2016-02-03

Stereocomplexation between enantiomeric poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) provides an avenue to greatly enhance performance of eco-friendly polylactide (PLA). Unfortunately, although the manufacturing of semicrystalline polymers generally involves melt processing, it is still hugely challenging to create high-performance stereocomplexed polylactide (sc-PLA) products from melt-processed high-molecular-weight PLLA/PDLA blends due to the weak crystallization memory effect of stereocomplex (sc) crystallites after complete melting as well as the substantial degradation of PLA chains at elevated melt-processing temperatures of ca. 240-260 °C. Inspired by the concept of powder metallurgy, here we report a new facile route to address these obstacles by sintering of sc-PLA powder at temperatures as low as 180-210 °C, which is distinctly different from traditional sintering of polymer powders performed at temperatures far exceeding their melting temperatures. The enantiomeric PLA chain segments from adjacent powder particles can interdiffuse across particle interfaces and co-crystallize into new sc crystallites capable of tightly welding the interfaces during the low-temperature sintering process, and thus highly transparent sc-PLA products with outstanding heat resistance, mechanical strength, and hydrolytic stability have been successfully fabricated for the first time.

Precision Voltage Referencing Techniques in MOS Technology.

NASA Astrophysics Data System (ADS)

Song, Bang-Sup

With the increasing complexity of functions on a single MOS chip, precision analog cicuits implemented in the same technology are in great demand so as to be integrated together with digital circuits. The future development of MOS data acquisition systems will require precision on-chip MOS voltage references. This dissertation will probe two most promising configurations of on-chip voltage references both in NMOS and CMOS technologies. In NMOS, an ion-implantation effect on the temperature behavior of MOS devices is investigated to identify the fundamental limiting factors of a threshold voltage difference as an NMOS voltage source. For this kind of voltage reference, the temperature stability on the order of 20ppm/(DEGREES)C is achievable with a shallow single-threshold implant and a low-current, high-body bias operation. In CMOS, a monolithic prototype bandgap reference is designed, fabricated and tested which embodies a curvature compensation and exhibits a minimized sensitivity to the process parameter variation. Experimental results imply that an average temperature stability on the order of 10ppm/(DEGREES)C with a production spread of less than 10ppm/(DEGREES)C feasible over the commercial temperature range.

Multilevel Resistance Programming in Conductive Bridge Resistive Memory

NASA Astrophysics Data System (ADS)

Mahalanabis, Debayan

This work focuses on the existence of multiple resistance states in a type of emerging non-volatile resistive memory device known commonly as Programmable Metallization Cell (PMC) or Conductive Bridge Random Access Memory (CBRAM), which can be important for applications such as multi-bit memory as well as non-volatile logic and neuromorphic computing. First, experimental data from small signal, quasi-static and pulsed mode electrical characterization of such devices are presented which clearly demonstrate the inherent multi-level resistance programmability property in CBRAM devices. A physics based analytical CBRAM compact model is then presented which simulates the ion-transport dynamics and filamentary growth mechanism that causes resistance change in such devices. Simulation results from the model are fitted to experimental dynamic resistance switching characteristics. The model designed using Verilog-a language is computation-efficient and can be integrated with industry standard circuit simulation tools for design and analysis of hybrid circuits involving both CMOS and CBRAM devices. Three main circuit applications for CBRAM devices are explored in this work. Firstly, the susceptibility of CBRAM memory arrays to single event induced upsets is analyzed via compact model simulation and experimental heavy ion testing data that show possibility of both high resistance to low resistance and low resistance to high resistance transitions due to ion strikes. Next, a non-volatile sense amplifier based flip-flop architecture is proposed which can help make leakage power consumption negligible by allowing complete shutdown of power supply while retaining its output data in CBRAM devices. Reliability and energy consumption of the flip-flop circuit for different CBRAM low resistance levels and supply voltage values are analyzed and compared to CMOS designs. Possible extension of this architecture for threshold logic function computation using the CBRAM devices as re

Successful fabrication of a convex platform PMMA cell-counting slide using a high-precision perpendicular dual-spindle CNC machine tool

NASA Astrophysics Data System (ADS)

Chen, Shun-Tong; Chang, Chih-Hsien

2013-12-01

This study presents a novel approach to the fabrication of a biomedical-mold for producing convex platform PMMA (poly-methyl-meth-acrylate) slides for counting cells. These slides allow for the microscopic examination of urine sediment cells. Manufacturing of such slides incorporates three important procedures: (1) the development of a tabletop high-precision dual-spindle CNC (computerized numerical control) machine tool; (2) the formation of a boron-doped polycrystalline composite diamond (BD-PCD) wheel-tool on the machine tool developed in procedure (1); and (3) the cutting of a multi-groove-biomedical-mold array using the formed diamond wheel-tool in situ on the developed machine. The machine incorporates a hybrid working platform providing wheel-tool thinning using spark erosion to cut, polish, and deburr microgrooves on NAK80 steel directly. With consideration given for the electrical conductive properties of BD-PCD, the diamond wheel-tool is thinned to a thickness of 5 µm by rotary wire electrical discharge machining. The thinned wheel-tool can grind microgrooves 10 µm wide. An embedded design, which inserts a close fitting precision core into the biomedical-mold to create step-difference (concave inward) of 50 µm in height between the core and the mold, is also proposed and realized. The perpendicular dual-spindles and precision rotary stage are features that allow for biomedical-mold machining without the necessity of uploading and repositioning materials until all tasks are completed. A PMMA biomedical-slide with a plurality of juxtaposed counting chambers is formed and its usefulness verified.

Fabrication and researching of weathering resistant double cladding power delivery fiber

NASA Astrophysics Data System (ADS)

Rong, Liang; Ren, Junjiang; Li, Rundong; Wang, Lianping; Zou, Huan

2016-01-01

A novel well weathering resistant power delivery fiber which is of double cladding and high optical energy transmitting ability is developed via fluoroplastic out sheath extruding process. The fiber has been comprehensively evaluated including optical performance, mechanical performance, environmental suitability and laser transmitting property. It is shown that the fiber has not only low attenuation, high numerical aperture and better mechanical bending performance, but also outstanding weathering resistance and high power laser transmitting performance, which implies the qualification of the fiber for various kinds of applying situations, such as laser ignition, laser induced expanding sound underwater, ship-based and airborne laser weapon.

Graded bit patterned magnetic arrays fabricated via angled low-energy He ion irradiation.

PubMed

Chang, L V; Nasruallah, A; Ruchhoeft, P; Khizroev, S; Litvinov, D

2012-07-11

A bit patterned magnetic array based on Co/Pd magnetic multilayers with a binary perpendicular magnetic anisotropy distribution was fabricated. The binary anisotropy distribution was attained through angled helium ion irradiation of a bit edge using hydrogen silsesquioxane (HSQ) resist as an ion stopping layer to protect the rest of the bit. The viability of this technique was explored numerically and evaluated through magnetic measurements of the prepared bit patterned magnetic array. The resulting graded bit patterned magnetic array showed a 35% reduction in coercivity and a 9% narrowing of the standard deviation of the switching field.

Precision medicine for advanced prostate cancer

PubMed Central

Mullane, Stephanie A.; Van Allen, Eliezer M.

2016-01-01

Purpose of review Precision cancer medicine, the use of genomic profiling of patient tumors at the point-of-care to inform treatment decisions, is rapidly changing treatment strategies across cancer types. Precision medicine for advanced prostate cancer may identify new treatment strategies and change clinical practice. In this review, we discuss the potential and challenges of precision medicine in advanced prostate cancer. Recent findings Although primary prostate cancers do not harbor highly recurrent targetable genomic alterations, recent reports on the genomics of metastatic castration-resistant prostate cancer has shown multiple targetable alterations in castration-resistant prostate cancer metastatic biopsies. Therapeutic implications include targeting prevalent DNA repair pathway alterations with PARP-1 inhibition in genomically defined subsets of patients, among other genomically stratified targets. In addition, multiple recent efforts have demonstrated the promise of liquid tumor profiling (e.g., profiling circulating tumor cells or cell-free tumor DNA) and highlighted the necessary steps to scale these approaches in prostate cancer. Summary Although still in the initial phase of precision medicine for prostate cancer, there is extraordinary potential for clinical impact. Efforts to overcome current scientific and clinical barriers will enable widespread use of precision medicine approaches for advanced prostate cancer patients. PMID:26909474

Thin silicon-solar cell fabrication

NASA Technical Reports Server (NTRS)

Lindmayer, J.

1979-01-01

Flexible silicon slices of uniform thicknesses are fabricated by etching in sodium hydroxide solution. Maintaining uniform thickness across slices during process(fabrication) is important for cell strength and resistance to damage in handling. Slices formed by procedure have reproducible surface with fine orange peel texture, and are far superior to slices prepared by other methods.

A low noise and high precision linear power supply with thermal foldback protection.

PubMed

Carniti, P; Cassina, L; Gotti, C; Maino, M; Pessina, G

2016-05-01

A low noise and high precision linear power supply was designed for use in rare event search experiments with macrobolometers. The circuit accepts at the input a "noisy" dual supply voltage up to ±15 V and gives at the output precise, low noise, and stable voltages that can be set between ±3.75 V and ±12.5 V in eight 1.25 V steps. Particular care in circuit design, component selection, and proper filtering results in a noise spectral density of 50nV/Hz at 1 Hz and 20nV/Hz white when the output is set to ±5 V. This corresponds to 125 nV RMS (0.8 μV peak to peak) between 0.1 Hz and 10 Hz, and 240 nV RMS (1.6 μV peak to peak) between 0.1 Hz and 100 Hz. The power supply rejection ratio (PSRR) of the circuit is 100 dB at low frequency, and larger than 40 dB up to high frequency, thanks to a proper compensation design. Calibration allows to reach a precision in the absolute value of the output voltage of ±70 ppm, or ±350 μV at ±5 V, and to reduce thermal drifts below ±1 ppm/(∘)C in the expected operating range. The maximum peak output current is about 6 A from each output. An original foldback protection scheme was developed that dynamically limits the maximum output current to keep the temperature of the output transistors within their safe operating range. An add-on card based on an ARM Cortex-M3 microcontroller is devoted to the monitoring and control of all circuit functionalities and provides remote communication via CAN bus.

Fabrication of large diffractive optical elements in thick film on a concave lens surface.

PubMed

Xie, Yongjun; Lu, Zhenwu; Li, Fengyou

2003-05-05

We demonstrate experimentally the technique of fabricating large diffractive optical elements (DOEs) in thick film on a concave lens surface (mirrors) with precise alignment by using the strategy of double exposure. We adopt the method of double exposure to overcome the difficulty of processing thick photoresist on a large curved substrate. A uniform thick film with arbitrary thickness on a concave lens can be obtained with this technique. We fabricate a large concentric circular grating with a 10-ìm period on a concave lens surface in film with a thickness of 2.0 ìm after development. It is believed that this technique can also be used to fabricate larger DOEs in thicker film on the concave or convex lens surface with precise alignment. There are other potential applications of this technique, such as fabrication of micro-optoelectromechanical systems (MOEMS) or microelectromechanical systems (MEMS) and fabrication of microlens arrays on a large concave lens surface or convex lens surface with precise alignment.

Low MITF/AXL ratio predicts early resistance to multiple targeted drugs in melanoma.

PubMed

Müller, Judith; Krijgsman, Oscar; Tsoi, Jennifer; Robert, Lidia; Hugo, Willy; Song, Chunying; Kong, Xiangju; Possik, Patricia A; Cornelissen-Steijger, Paulien D M; Geukes Foppen, Marnix H; Kemper, Kristel; Goding, Colin R; McDermott, Ultan; Blank, Christian; Haanen, John; Graeber, Thomas G; Ribas, Antoni; Lo, Roger S; Peeper, Daniel S

2014-12-15

Increased expression of the Microphthalmia-associated transcription factor (MITF) contributes to melanoma progression and resistance to BRAF pathway inhibition. Here we show that the lack of MITF is associated with more severe resistance to a range of inhibitors, while its presence is required for robust drug responses. Both in primary and acquired resistance, MITF levels inversely correlate with the expression of several activated receptor tyrosine kinases, most frequently AXL. The MITF-low/AXL-high/drug-resistance phenotype is common among mutant BRAF and NRAS melanoma cell lines. The dichotomous behaviour of MITF in drug response is corroborated in vemurafenib-resistant biopsies, including MITF-high and -low clones in a relapsed patient. Furthermore, drug cocktails containing AXL inhibitor enhance melanoma cell elimination by BRAF or ERK inhibition. Our results demonstrate that a low MITF/AXL ratio predicts early resistance to multiple targeted drugs, and warrant clinical validation of AXL inhibitors to combat resistance of BRAF and NRAS mutant MITF-low melanomas.

Fabrication of large area woodpile structure in polymer

NASA Astrophysics Data System (ADS)

Gupta, Jaya Prakash; Dutta, Neilanjan; Yao, Peng; Sharkawy, Ahmed S.; Prather, Dennis W.

2009-02-01

A fabrication process of three-dimensional Woodpile photonic crystals based on multilayer photolithography from commercially available photo resist SU8 have been demonstrated. A 6-layer, 2 mm × 2mm woodpile has been fabricated. Different factors that influence the spin thickness on multiple resist application have been studied. The fabrication method used removes, the problem of intermixing, and is more repeatable and robust than the multilayer fabrication techniques for three dimensional photonic crystal structures that have been previously reported. Each layer is developed before next layer photo resist spin, instead of developing the whole structure in the final step as used in multilayer process. The desired thickness for each layer is achieved by the calibration of spin speed and use of different photo resist compositions. Deep UV exposure confinement has been the defining parameter in this process. Layer uniformity for every layer is independent of the previous developed layers and depends on the photo resist planarizing capability, spin parameters and baking conditions. The intermixing problem, which results from the previous layers left uncrossed linked photo resist, is completely removed in this process as the previous layers are fully developed, avoiding any intermixing between the newly spun and previous layers. Also this process gives the freedom to redo every spin any number of times without affecting the previously made structure, which is not possible in other multilayer process where intermediate developing is not performed.

Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

NASA Astrophysics Data System (ADS)

Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

2012-07-01

In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

Kaleidoscopic imaging patterns of complex structures fabricated by laser-induced deformation

PubMed Central

Zhang, Haoran; Yang, Fengyou; Dong, Jianjie; Du, Lena; Wang, Chuang; Zhang, Jianming; Guo, Chuan Fei; Liu, Qian

2016-01-01

Complex surface structures have stimulated a great deal of interests due to many potential applications in surface devices. However, in the fabrication of complex surface micro-/nanostructures, there are always great challenges in precise design, or good controllability, or low cost, or high throughput. Here, we present a route for the accurate design and highly controllable fabrication of surface quasi-three-dimensional (quasi-3D) structures based on a thermal deformation of simple two-dimensional laser-induced patterns. A complex quasi-3D structure, coaxially nested convex–concave microlens array, as an example, demonstrates our capability of design and fabrication of surface elements with this method. Moreover, by using only one relief mask with the convex–concave microlens structure, we have gotten hundreds of target patterns at different imaging planes, offering a cost-effective solution for mass production in lithography and imprinting, and portending a paradigm in quasi-3D manufacturing. PMID:27910852

Low-cost fabrication of optical waveguides, interconnects and sensing structures on all-polymer-based thin foils

NASA Astrophysics Data System (ADS)

Rezem, Maher; Kelb, Christian; Günther, Axel; Rahlves, Maik; Reithmeier, Eduard; Roth, Bernhard

2016-03-01

Micro-optical sensors based on optical waveguides are widely used to measure temperature, force and strain but also to detect biological and chemical substances such as explosives or toxins. While optical micro-sensors based on silicon technology require complex and expensive process technologies, a new generation of sensors based completely on polymers offer advantages especially in terms of low-cost and fast production techniques. We have developed a process to integrate micro-optical components such as embedded waveguides and optical interconnects into polymer foils with a thickness well below one millimeter. To enable high throughput production, we employ hot embossing technology, which is capable of reel-to-reel fabrication with a surface roughness in the optical range. For the waveguide fabrication, we used the thermoplastic polymethylmethacrylate (PMMA) as cladding and several optical adhesives as core materials. The waveguides are characterized with respect to refractive indices and propagation losses. We achieved propagation losses are as low as 0.3 dB/cm. Furthermore, we demonstrate coupling structures and their fabrication especially suited to integrate various light sources such as vertical-cavity surface-emitting lasers (VCSEL) and organic light emitting diodes (OLED) into thin polymer foils. Also, we present a concept of an all-polymer and waveguide based deformation sensor based on intensity modulation, which can be fabricated by utilizing our process. For future application, we aim at a low-cost and high-throughput reel-to-reel production process enabling the fabrication of large sensor arrays or disposable single-use sensing structures, which will open optical sensing to a large variety of application fields ranging from medical diagnosis to automotive sensing.

Training resource for precision opticians

NASA Astrophysics Data System (ADS)

Williamson, Ray

2007-05-01

A new, comprehensive course of study in optical fabrication and testing has been created and is available to companies, schools, and individuals. It is aimed at aspiring and practicing precision opticians. The author is collaborating with OptiMax to further enhance presentations through animation and videography. Additional modules are being created. The need for such a course, and its goals and syllabus, are described.

Enhanced Oxidation-Resistant Cu@Ni Core-Shell Nanoparticles for Printed Flexible Electrodes.

PubMed

Kim, Tae Gon; Park, Hye Jin; Woo, Kyoohee; Jeong, Sunho; Choi, Youngmin; Lee, Su Yeon

2018-01-10

In this work, the fabrication and application of highly conductive, robust, flexible, and oxidation-resistant Cu-Ni core-shell nanoparticle (NP)-based electrodes have been reported. Cu@Ni core-shell NPs with a tunable Ni shell thickness were synthesized by varying the Cu/Ni molar ratios in the precursor solution. Through continuous spray coating and flash photonic sintering without an inert atmosphere, large-area Cu@Ni NP-based conductors were fabricated on various polymer substrates. These NP-based electrodes demonstrate a low sheet resistance of 1.3 Ω sq -1 under an optical energy dose of 1.5 J cm -2 . In addition, they exhibit highly stable sheet resistances (ΔR/R 0 < 1) even after 30 days of aging at 85 °C and 85% relative humidity. Further, a flexible heater fabricated from the Cu@Ni film is demonstrated, which shows uniform heat distribution and stable temperature compared to those of a pure Cu film.

Fabrication and Characterization of Fully Transparent ZnO Thin-Film Transistors and Self-Switching Nano-Diodes

NASA Astrophysics Data System (ADS)

Sun, Y.; Ashida, K.; Sasaki, S.; Koyama, M.; Maemoto, T.; Sasa, S.; Kasai, S.; Iñiguez-de-la-Torre, I.; González, T.

2015-10-01

Fully transparent zinc oxide (ZnO) based thin-film transistors (TFTs) and a new type of rectifiers calls self-switching nano-diodes (SSDs) were fabricated on glass substrates at room temperature by using low resistivity and transparent conducting Al- doped ZnO (AZO) thin-films. The deposition conditions of AZO thin-films were optimized with pulsed laser deposition (PLD). AZO thin-films on glass substrates were characterized and the transparency of 80% and resistivity with 1.6*10-3 Ωcm were obtained of 50 nm thickness. Transparent ZnO-TFTs were fabricated on glass substrates by using AZO thin-films as electrodes. A ZnO-TFT with 2 μm long gate device exhibits a transconductance of 400 μS/mm and an ON/OFF ratio of 2.8*107. Transparent ZnO-SSDs were also fabricated by using ZnO based materials and clear diode-like characteristics were observed.

Low-temperature fabrication of alkali metal-organic charge transfer complexes on cotton textile for optoelectronics and gas sensing.

PubMed

Ramanathan, Rajesh; Walia, Sumeet; Kandjani, Ahmad Esmaielzadeh; Balendran, Sivacarendran; Mohammadtaheri, Mahsa; Bhargava, Suresh Kumar; Kalantar-zadeh, Kourosh; Bansal, Vipul

2015-02-03

A generalized low-temperature approach for fabricating high aspect ratio nanorod arrays of alkali metal-TCNQ (7,7,8,8-tetracyanoquinodimethane) charge transfer complexes at 140 °C is demonstrated. This facile approach overcomes the current limitation associated with fabrication of alkali metal-TCNQ complexes that are based on physical vapor deposition processes and typically require an excess of 800 °C. The compatibility of soft substrates with the proposed low-temperature route allows direct fabrication of NaTCNQ and LiTCNQ nanoarrays on individual cotton threads interwoven within the 3D matrix of textiles. The applicability of these textile-supported TCNQ-based organic charge transfer complexes toward optoelectronics and gas sensing applications is established.

Precision engineering center. 1988 Annual report, Volume VI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dow, T.; Fornaro, R.; Keltie, R.

To reverse the downward trend in the balance of trade, American companies must concentrate on increasing research into new products, boosting productivity, and improving manufacturing processes. The Precision Engineering Center at North Carolina State University is a multidisciplinary research and graduate education program dedicated to providing the new technology necessary to respond to this challenge. One extremely demanding manufacturing area is the fabrication and assembly of optical systems. These systems are at the heart of such consumer products as cameras, lenses, copy machines, laser bar-code scanners, VCRs, and compact audio discs - products that the Japanese and other East Asianmore » countries are building dominance. A second critical area is the fabrication of VLSI and ULSI circuits. The tolerances required to produce the next generation of components for such systems have created the need for new approaches - approaches that could either make or break America`s competitive position. This report contains individual reports on research projects grouped into three broad areas: measurement and actuation; real-time control; precision fabrication. Separate abstracts for these articles have been indexed into the energy database.« less

Electrical, structural and surface morphological properties of thermally stable low-resistance W/Ti/Au multilayer ohmic contacts to n-type GaN

NASA Astrophysics Data System (ADS)

Jyothi, I.; Reddy, V. Rajagopal

2010-10-01

A W/Ti/Au multilayer scheme has been fabricated for achieving thermally stable low-resistance ohmic contact to n-type GaN (4.0 × 10 18 cm -3). It is shown that the as-deposited W/Ti/Au contact exhibits near linear I- V behaviour. However, annealing at temperature below 800 °C the contacts exhibit non-linear behaviour. After annealing at a temperature in excess of 850 °C, the W/Ti/Au contact showed ohmic behaviour. The W/Ti/Au contact produced specific contact resistance as low as 6.7 × 10 -6 Ω cm 2 after annealing at 900 °C for 1 min in a N 2 ambient. It is noted that the specific contact resistance decreases with increase in annealing temperature. It is also noted that annealing the contacts at 900 °C for 30 min causes insignificant degradation of the electrical and thermal properties. It is further shown that the overall surface morphology of the W/Ti/Au stayed fairly smooth even after annealing at 900 °C. The W/Ti/Au ohmic contact showed good edge sharpness after annealing at 900 °C for 30 min. Based on the Auger electron spectroscopy and glancing angle X-ray diffraction results, possible explanation for the annealing dependence of the specific contact resistance of the W/Ti/Au contacts are described and discussed.

Quarzt Fabric Insights Across a Low P-High T Shear Zone

NASA Astrophysics Data System (ADS)

Gomez Barreiro, J.; Martinez-Catalan, J. R.; Benitez Perez, J.; Wenk, H.; Vogel, S. C.; Alcock, J. E.

2013-12-01

The evolution of mylonitic fabric in quartzites across a Low-P / High-T gradient within the Lugo Dome Extensional system (NW Spain) is analyzed. Quantitative texture measurements with TOF neutron diffraction, Shape preferred orientation (SPO) and Crystal Size Distribution (CSD) analyses were correlated with tectonothermal data to constraint the prevalence of ductile deformative fabrics exposed to cycles of dynamic and static recrystallization. Results suggest two stages in the evolution of mylonites in close correlation to thermal gradient, 1) a pervasive ductile deformation affecting most of the shear zone volume, with the development of symmetric cross girdle c-axes fabric suggesting slip on {c,r,m} and dynamically recrystallized microstructures which resulted into the refinement of the grain-size. 2) An heterogeneous deformation stage where strain partition led to the formation of relatively active and passive domains. During this late stage, at deeper levels, High T detachments show [c]{m} slip system and dynamic recrystallization activation, with monoclinic texture patterns, meanwhile, passive domains followed an static recrystallization with abnormal grain growth and minor variation of early orthogonal texture patterns Neutron diffraction data (cross) and Rietveld model obtained with MAUD (solid line) of a mylonitic quartzite. Some important planes are indicated for the major phases.

Adherence to a low-fat vs. low-carbohydrate diet differs by insulin resistance status.

PubMed

McClain, A D; Otten, J J; Hekler, E B; Gardner, C D

2013-01-01

Previous research shows diminished weight loss success in insulin-resistant (IR) women assigned to a low-fat (LF) diet compared to those assigned to a low-carbohydrate (LC) diet. These secondary analyses examined the relationship between insulin-resistance status and dietary adherence to either a LF-diet or LC-diet among 81 free-living, overweight/obese women [age = 41.9 ± 5.7 years; body mass index (BMI) = 32.6 ± 3.6 kg/m(2)]. This study found differential adherence by insulin-resistance status only to a LF-diet, not a LC-diet. IR participants were less likely to adhere and lose weight on a LF-diet compared to insulin-sensitive (IS) participants assigned to the same diet. There were no significant differences between IR and IS participants assigned to LC-diet in relative adherence or weight loss. These results suggest that insulin resistance status may affect dietary adherence to weight loss diets, resulting in higher recidivism and diminished weight loss success of IR participants advised to follow LF-diets for weight loss. © 2012 Blackwell Publishing Ltd.

Highly flexible and electroforming free resistive switching behavior of tungsten disulfide flakes fabricated through advanced printing technology

NASA Astrophysics Data System (ADS)

Muqeet Rehman, Muhammad; Uddin Siddiqui, Ghayas; Doh, Yang Hoi; Choi, Kyung Hyun

2017-09-01

Tungsten disulfide (WS2) is a transition metal dichalcogenide that differs from other 2D materials such as graphene owing to its distinctive semiconducting nature and tunable band gap. In this study, we have reported the structural, electrical, physical, and mechanical properties of exfoliated WS2 flakes and used them as the functional layer of a rewritable bipolar memory device. We demonstrate this concept by sandwiching few-layered WS2 flakes between two silver (Ag) electrodes on a flexible and transparent PET substrate. The entire device fabrication was carried out through all-printing technology such as reverse offset printing for patterning bottom electrodes, electrohydrodynamic (EHD) atomization for depositing functional thin film and EHD patterning for depositing the top electrode respectively. The memory device was further encapsulated with an atomically thin layer of aluminum oxide (Al2O3), deposited through a spatial atmospheric atomic layer deposition system to protect it against a humid environment. Remarkable resistive switching results were obtained, such as nonvolatile bipolar behavior, a high switching ratio (∼103), a long retention time (∼105 s), high endurance (1500 voltage sweeps), a low operating voltage (∼2 V), low current compliance (50 μA), mechanical robustness (1500 cycles) and unique repeatability at ambient conditions. Ag/WS2/Ag-based memory devices offer a new possibility for integration in flexible electronic devices.

Low-resistance 2D/2D ohmic contacts: A universal approach to high-performance WSe 2, MoS 2, and MoSe 2 transistors

DOE PAGES

Chuang, Hsun -Jen; Chamlagain, Bhim; Koehler, Michael; ...

2016-02-04

Here, we report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe 2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ~0.3 kΩ μm, high on/off ratios up to >10 9, and high drive currents exceeding 320 μA μm –1. These favorable characteristics are combined with a two-terminal field-effect hole mobility μ FE ≈ 2 × 10 2 cm 2 V –1 smore » –1 at room temperature, which increases to >2 × 10 3 cm 2 V –1 s –1 at cryogenic temperatures. We observe a similar performance also in MoS 2 and MoSe 2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in postsilicon electronics.« less

A novel highly porous ceramic foam with efficient thermal insulation and high temperature resistance properties fabricated by gel-casting process

NASA Astrophysics Data System (ADS)

Yu, Jiahong; Wang, Guixiang; Tang, Di; Qiu, Ya; Sun, Nali; Liu, Wenqiao

2018-01-01

The design of super thermal insulation and high-temperature resistant materials for high temperature furnaces is crucial due to the energy crisis and the huge wasting. Although it is told that numerous studies have been reported about various of thermal insulation materials prepared by different methods, the applications of yttria-stabilized zirconia (YSZ) ceramic foams fabricated through tert-butyl alcohol (TBA)-based gel-casting process in bulk thermal isolators were barely to seen. In this paper, highly porous yttria-stabilized zirconia (YSZ) ceramic foams were fabricated by a novel gel-casting method using tert-butyl alcohol (TBA) as solvent and pore-forming agent. Different raw material ratio, sintering temperature and soaking time were all investigated to achieve optimal thermal insulation and mechanical properties. We can conclude that porosity drops gradually while compressive strength increases significantly with the rising temperature from 1000-1500°C. With prolonged soaking time, there is no obvious change in porosity but compressive strength increases gradually. All specimens have uniformly distributed pores with average size of 0.5-2μm and show good structural stability at high temperature. The final obtained ceramic foams displayed an outstanding ultra-low thermal conductivity property with only 200.6 °C in cold surface while the hot side was 1000 °C (hold 60 min to keep thermal balance before testing) at the thickness of 10 mm.

Fabrication of polysiloxane-modified polyurethane sponge as low-cost organics/water separation and selective absorption material.

PubMed

Cui, Zhengshan; He, Wanxia; Liu, Jun; Wei, Wei; Jiang, Liang; Huang, Jun; Lv, Xiaomeng

2016-10-01

Through sol-gel and dip-coating processes, commercial polyurethane sponge modified by polysiloxane was fabricated under low temperature (60 °C) and atmosphere. The contact angle of the obtained polysiloxane/polyurethane sponge is 145 ± 5°. Hence, the polysiloxane/polyurethane sponge could float on water and selectively absorb organics from the surface of the water, indicating simultaneous properties of hydrophobicity and oleophilicity. The absorbent maximum value is 50-150 times of its own weight. The polysiloxane/polyurethane sponge exhibited excellent recyclability, which could be reused by squeezing the sponge due to its high mechanical stability and flexibility. Thermogravimetry-differential thermal analysis test indicated that the polysiloxane/polyurethane sponge exhibited good thermal stability and the stable contact angle of samples tested under increasing temperature indicated its good weather resistance. Due to the commercial property of polyurethane sponge and easy-handling of polysiloxane, the polysiloxane/polyurethane sponge can be easily scaled up to recover a large-area oil spill in water and further work based on the designed equipment has been under consideration.

A flexible nonvolatile resistive switching memory device based on ZnO film fabricated on a foldable PET substrate.

PubMed

Sun, Bai; Zhang, Xuejiao; Zhou, Guangdong; Yu, Tian; Mao, Shuangsuo; Zhu, Shouhui; Zhao, Yong; Xia, Yudong

2018-06-15

In this work, a flexible resistive switching memory device based on ZnO film was fabricated using a foldable Polyethylene terephthalate (PET) film as substrate while Ag and Ti acts top and bottom electrode. Our as-prepared device represents an outstanding nonvolatile memory behavior with good "write-read-erase-read" stability at room temperature. Finally, a physical model of Ag conductive filament is constructed to understanding the observed memory characteristics. The work provides a new way for the preparation of flexible memory devices based on ZnO films, and especially provides an experimental basis for the exploration of high-performance and portable nonvolatile resistance random memory (RRAM). Copyright © 2018 Elsevier Inc. All rights reserved.

Fabrication of Josephson Junction without shadow evaporation

NASA Astrophysics Data System (ADS)

Wu, Xian; Ku, Hsiangsheng; Long, Junling; Pappas, David

We developed a new method of fabricating Josephson Junction (Al/AlOX/Al) without shadow evaporation. Statistics from room temperature junction resistance and measurement of qubits are presented. Unlike the traditional ``Dolan Bridge'' technique, this method requires two individual lithographies and straight evaporations of Al. Argon RF plasma is used to remove native AlOX after the first evaporation, followed by oxidation and second Al evaporation. Junction resistance measured at room temperature shows linear dependence on Pox (oxidation pressure), √{tox} (oxidation time), and inverse proportional to junction area. We have seen 100% yield of qubits made with this method. This method is promising because it eliminates angle dependence during Junction fabrication, facilitates large scale qubits fabrication.

Targeting ALK: Precision Medicine Takes On Drug Resistance

PubMed Central

Lin, Jessica J.; Riely, Gregory J.; Shaw, Alice T.

2017-01-01

Anaplastic lymphoma kinase (ALK) is a validated molecular target in several ALK-rearranged malignancies, including non-small-cell lung cancer (NSCLC). However, the clinical benefit of targeting ALK using tyrosine kinase inhibitors (TKIs) is almost universally limited by the emergence of drug resistance. Diverse mechanisms of resistance to ALK TKIs have now been discovered, and these basic mechanisms are informing the development of novel therapeutic strategies to overcome resistance in the clinic. In this Review, we summarize the current successes and challenges of targeting ALK. PMID:28122866

Novel WSi/Au T-shaped gate GaAs metal-semiconductor field-effect-transistor fabrication process for super low-noise microwave monolithic integrated circuit amplifiers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takano, H.; Hosogi, K.; Kato, T.

1995-05-01

A fully ion-implanted self-aligned T-shaped gate Ga As metal-semiconductor field-effect transistor (MESFET) with high frequency and extremely low-noise performance has been successfully fabricated for super low-noise microwave monolithic integrated circuit (MMIC) amplifiers. A subhalf-micrometer gate structure composed of WSi/Ti/Mo/Au is employed to reduce gate resistance effectively. This multilayer gate structure is formed by newly developed dummy SiON self-alignment technology and a photoresist planarization process. At an operating frequency of 12 GHz, a minimum noise figure of 0.87 dB with an associated gain of 10.62 dB has been obtained. Based on the novel FET process, a low-noise single-stage MMIC amplifier withmore » an excellent low-noise figure of 1.2 dB with an associated gain of 8 dB in the 14 GHz band has been realized. This is the lowest noise figure ever reported at this frequency for low-noise MMICs based on ion-implanted self-aligned gate MESFET technology. 14 refs., 9 figs.« less

Aqueous-Based Fabrication of Low-VOC Nanostructured Block Copolymer Films as Potential Marine Antifouling Coatings.

PubMed

Kim, Kris S; Gunari, Nikhil; MacNeil, Drew; Finlay, John; Callow, Maureen; Callow, James; Walker, Gilbert C

2016-08-10

The ability to fabricate nanostructured films by exploiting the phenomenon of microphase separation has made block copolymers an invaluable tool for a wide array of coating applications. Standard approaches to engineering nanodomains commonly involve the application of organic solvents, either through dissolution or annealing protocols, resulting in the release of volatile organic compounds (VOCs). In this paper, an aqueous-based method of fabricating low-VOC nanostructured block copolymer films is presented. The reported procedure allows for the phase transfer of water insoluble triblock copolymer, poly(styrene-block-2 vinylpyridine-block-ethylene oxide) (PS-b-P2VP-b-PEO), from a water immiscible phase to an aqueous environment with the assistance of a diblock copolymeric phase transfer agent, poly(styrene-block-ethylene oxide) (PS-b-PEO). Phase transfer into the aqueous phase results in self-assembly of PS-b-P2VP-b-PEO into core-shell-corona micelles, which are characterized by dynamic light scattering techniques. The films that result from coating the micellar solution onto Si/SiO2 surfaces exhibit nanoscale features that disrupt the ability of a model foulant, a zoospore of Ulva linza, to settle. The multilayered architecture consists of a pH-responsive P2VP-"shell" which can be stimulated to control the size of these features. The ability of these nanostructured thin films to resist protein adsorption and serve as potential marine antifouling coatings is supported through atomic force microscopy (AFM) and analysis of the settlement of Ulva linza zoospore. Field trials of the surfaces in a natural environment show the inhibition of macrofoulants for 1 month.

Resistive Switching of Ta2O5-Based Self-Rectifying Vertical-Type Resistive Switching Memory

NASA Astrophysics Data System (ADS)

Ryu, Sungyeon; Kim, Seong Keun; Choi, Byung Joon

2018-01-01

To efficiently increase the capacity of resistive switching random-access memory (RRAM) while maintaining the same area, a vertical structure similar to a vertical NAND flash structure is needed. In addition, the sneak-path current through the half-selected neighboring memory cell should be mitigated by integrating a selector device with each RRAM cell. In this study, an integrated vertical-type RRAM cell and selector device was fabricated and characterized. Ta2O5 as the switching layer and TaOxNy as the selector layer were used to preliminarily study the feasibility of such an integrated device. To make the side contact of the bottom electrode with active layers, a thick Al2O3 insulating layer was placed between the Pt bottom electrode and the Ta2O5/TaOxNy stacks. Resistive switching phenomena were observed under relatively low currents (below 10 μA) in this vertical-type RRAM device. The TaOxNy layer acted as a nonlinear resistor with moderate nonlinearity. Its low-resistance-state and high-resistance-state were well retained up to 1000 s.

Facile fabrication of carbon brush with reduced graphene oxide (rGO) for decreasing resistance and accelerating pollutants removal in bio-electrochemical systems.

PubMed

Cui, Dan; Yang, Li-Ming; Liu, Wen-Zong; Cui, Min-Hua; Cai, Wei-Wei; Wang, Ai-Jie

2018-07-15

Low electrode resistance is crucial for achieving efficient reactions in bio-electrochemical system (BES), especially considering the factors of BES scaling-up and microbial effects. Graphene has revealed a cornucopia of potential applications due to its high conductivity and extraordinary electrochemical properties. Here, significant reduction of electrode resistance and increment of electrochemical activity were achieved by fabricating the three-dimensional carbon brush using reduced graphene oxide (rGO/carbon brush) through one-step electro-deposition without any binder. The rGO/carbon brush was employed as cathode in BES equipped with bio-anode for azo compound (AO7) removal. The charge transfer resistances of cathode part and whole cell were decreased by 89% and 65%, respectively. The reactor showed quickly start-up within 48 h with peak cycle current six fold increase relative to the control. AO7 decolorization efficiency reached 91.1 ± 0.1% at 4 h and 97.6 ± 0.4% at 6 h. Effective decolorization of AO7 was at rate up to 650.7 g AO7/m 3 ·h. The results indicated that the advantages of graphene and three-dimensional carbon brush successfully improved the overall performance of BES and enhanced refractory pollutants removal when applied to specific wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

Electroforming free controlled bipolar resistive switching in Al/CoFe2O4/FTO device with self-compliance effect

NASA Astrophysics Data System (ADS)

Munjal, Sandeep; Khare, Neeraj

2018-02-01

Controlled bipolar resistive switching (BRS) has been observed in nanostructured CoFe2O4 (CFO) films using an Al (aluminum)/CoFe2O4/FTO (fluorine-doped tin oxide) device. The fabricated device shows electroforming-free uniform BRS with two clearly distinguished and stable resistance states without any application of compliance current, with a resistance ratio of the high resistance state (HRS) and the low resistance state (LRS) of >102. Small switching voltage (<1 volt) and lower current in both the resistance states confirm the fabrication of a low power consumption device. In the LRS, the conduction mechanism was found to be Ohmic in nature, while the high-resistance state (HRS/OFF state) was governed by the space charge-limited conduction mechanism, which indicates the presence of an interfacial layer with an imperfect microstructure near the top Al/CFO interface. The device shows nonvolatile behavior with good endurance properties, an acceptable resistance ratio, uniform resistive switching due to stable, less random filament formation/rupture, and a control over the resistive switching properties by choosing different stop voltages, which makes the device suitable for its application in future nonvolatile resistive random access memory.

Hybrid Wound Filaments for Greater Resistance to Impacts

NASA Technical Reports Server (NTRS)

DeLay, Thomas K.; Patterson, James E.; Olson, Michael A.

2008-01-01

A hybrid material containing wound filaments made of a hybrid of high-strength carbon fibers and poly(phenylene benzobisoxazole) [PBO] fibers is discussed. This hybrid material is chosen in an effort to increase the ability of the pressure vessel to resist damage by low-speed impacts (e.g., dropping of tools on the vessel or bumping of the vessel against hard objects during installation and use) without significantly increasing the weight of the vessel. While the basic concept of hybridizing fibers in filament-wound structures is not new, the use of hybridization to increase resistance to impacts is an innovation, and can be expected to be of interest in the composite-pressure-vessel industry. The precise types and the proportions of the high-strength carbon fibers and the PBO fibers in the hybrid are chosen, along with the filament-winding pattern, to maximize the advantageous effects and minimize the disadvantageous effects of each material. In particular, one seeks to (1) take advantage of the ability of the carbon fibers to resist stress rupture while minimizing their contribution to vulnerability of the vessel to impact damage and (2) take advantage of the toughness of the PBO fibers while minimizing their contribution to vulnerability of the vessel to stress rupture. Experiments on prototype vessels fabricated according to this concept have shown promising results. At the time of reporting the information for this article, research toward understanding and optimizing the performances of PBO fibers so as to minimize their contribution to vulnerability of the pressure vessel to stress rupture had yet to be performed.

Hollow waveguides with low intrinsic photoluminescence fabricated with Ta2O5 and SiO2 films

NASA Astrophysics Data System (ADS)

Zhao, Y.; Jenkins, M.; Measor, P.; Leake, K.; Liu, S.; Schmidt, H.; Hawkins, A. R.

2011-02-01

A type of integrated hollow core waveguide with low intrinsic photoluminescence fabricated with Ta2O5 and SiO2 films is demonstrated. Hollow core waveguides made with a combination of plasma-enhanced chemical vapor deposition SiO2 and sputtered Ta2O5 provide a nearly optimal structure for optofluidic biofluorescence measurements with low optical loss, high fabrication yield, and low background photoluminescence. Compared to earlier structures made using Si3N4, the photoluminescence background of Ta2O5 based hollow core waveguides is decreased by a factor of 10 and the signal-to-noise ratio for fluorescent nanobead detection is improved by a factor of 12.

Low-Cost and Rapid Fabrication of Metallic Nanostructures for Sensitive Biosensors Using Hot-Embossing and Dielectric-Heating Nanoimprint Methods.

PubMed

Lee, Kuang-Li; Wu, Tsung-Yeh; Hsu, Hsuan-Yeh; Yang, Sen-Yeu; Wei, Pei-Kuen

2017-07-02

We propose two approaches-hot-embossing and dielectric-heating nanoimprinting methods-for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures on A4 size plastic films are fabricated by evaporating aluminum film on hot-embossing nanostructures. The narrowest bandwidth of the Fano resonance is only 2.7 nm in the visible light region. The periodic aluminum nanostructure achieves a figure of merit of 150, and an intensity sensitivity of 29,345%/RIU (refractive index unit). The rapid fabrication is also achieved by using radio-frequency (RF) sensitive plastic films and a commercial RF welding machine. The dielectric-heating, using RF power, takes advantage of the rapid heating/cooling process and lower electric power consumption. The fabricated capped aluminum nanoslit array has a 5 nm Fano linewidth and 490.46 nm/RIU wavelength sensitivity. The biosensing capabilities of the metallic nanostructures are further verified by measuring antigen-antibody interactions using bovine serum albumin (BSA) and anti-BSA. These rapid and high-throughput fabrication methods can benefit low-cost, highly sensitive biosensors and other sensing applications.

Low-Cost and Rapid Fabrication of Metallic Nanostructures for Sensitive Biosensors Using Hot-Embossing and Dielectric-Heating Nanoimprint Methods

PubMed Central

Lee, Kuang-Li; Wu, Tsung-Yeh; Hsu, Hsuan-Yeh; Yang, Sen-Yeu; Wei, Pei-Kuen

2017-01-01

We propose two approaches—hot-embossing and dielectric-heating nanoimprinting methods—for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures on A4 size plastic films are fabricated by evaporating aluminum film on hot-embossing nanostructures. The narrowest bandwidth of the Fano resonance is only 2.7 nm in the visible light region. The periodic aluminum nanostructure achieves a figure of merit of 150, and an intensity sensitivity of 29,345%/RIU (refractive index unit). The rapid fabrication is also achieved by using radio-frequency (RF) sensitive plastic films and a commercial RF welding machine. The dielectric-heating, using RF power, takes advantage of the rapid heating/cooling process and lower electric power consumption. The fabricated capped aluminum nanoslit array has a 5 nm Fano linewidth and 490.46 nm/RIU wavelength sensitivity. The biosensing capabilities of the metallic nanostructures are further verified by measuring antigen–antibody interactions using bovine serum albumin (BSA) and anti-BSA. These rapid and high-throughput fabrication methods can benefit low-cost, highly sensitive biosensors and other sensing applications. PMID:28671600

Comparing the accuracy (trueness and precision) of models of fixed dental prostheses fabricated by digital and conventional workflows.

PubMed

Sim, Ji-Young; Jang, Yeon; Kim, Woong-Chul; Kim, Hae-Young; Lee, Dong-Hwan; Kim, Ji-Hwan

2018-03-31

This study aimed to evaluate and compare the accuracy. A reference model was prepared with three prepared teeth for three types of restorations: single crown, 3-unit bridge, and inlay. Stone models were fabricated from conventional impressions. Digital impressions of the reference model were created using an intraoral scanner (digital models). Physical models were fabricated using a three-dimensional (3D) printer. Reference, stone, and 3D printed models were subsequently scanned using an industrial optical scanner; files were exported in a stereolithography file format. All datasets were superimposed using 3D analysis software to evaluate the accuracy of the complete arch and trueness of the preparations. One-way and two-way analyses of variance (ANOVA) were performed to compare the accuracy among the three model groups and evaluate the trueness among the three types of preparation. For the complete arch, significant intergroup differences in precision were observed for the three groups (p<.001). However, no significant difference in trueness was found between the stone and digital models (p>.05). 3D printed models had the poorest accuracy. A two-way ANOVA revealed significant differences in trueness among the model groups (p<.001) and types of preparation (p<.001). Digital models had smaller root mean square values of trueness of the complete arch and preparations than stone models. However, the accuracy of the complete arch and trueness of the preparations of 3D printed models were inferior to those of the other groups. Copyright © 2018 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Fabrication of two-dimensional visible wavelength nanoscale plasmonic structures using hydrogen silsesquioxane based resist

NASA Astrophysics Data System (ADS)

Smith, Kyle Z.; Gadde, Akshitha; Kadiyala, Anand; Dawson, Jeremy M.

2016-03-01

In recent years, the global market for biosensors has continued to increase in combination with their expanding use in areas such as biodefense/detection, home diagnostics, biometric identification, etc. A constant necessity for inexpensive, portable bio-sensing methods, while still remaining simple to understand and operate, is the motivation behind novel concepts and designs. Labeled visible spectrum bio-sensing systems provide instant feedback that is both simple and easy to work with, but are limited by the light intensity thresholds required by the imaging systems. In comparison, label-free bio-sensing systems and other detection modalities like electrochemical, frequency resonance, thermal change, etc., can require additional technical processing steps to convey the final result, increasing the system's complexity and possibly the time required for analysis. Further decrease in the detection limit can be achieved through the addition of plasmonic structures into labeled bio-sensing systems. Nano-structures that operate in the visible spectrum have feature sizes typically in the order of the operating wavelength, calling for high aspect ratio nanoscale fabrication capabilities. In order to achieve these dimensions, electron beam lithography (EBL) is used due to its accurate feature production. Hydrogen silsesquioxane (HSQ) based electron beam resist is chosen for one of its benefits, which is after exposure to oxygen plasma, the patterned resist cures into silicon dioxide (SiO2). These cured features in conjunction with nanoscale gold particles help in producing a high electric field through dipole generation. In this work, a detailed process flow of the fabrication of square lattice of plasmonic structures comprising of gold coated silicon dioxide pillars designed to operate at 560 nm wavelength and produce an intensity increase of roughly 100 percent will be presented.

Fabrication of Low-Noise TES Arrays for the SAFARI Instrument on SPICA

NASA Astrophysics Data System (ADS)

Ridder, M. L.; Khosropanah, P.; Hijmering, R. A.; Suzuki, T.; Bruijn, M. P.; Hoevers, H. F. C.; Gao, J. R.; Zuiddam, M. R.

2016-07-01

Ultra-low-noise transition edge sensors (TES) with noise equivalent power lower than 2 × 10^{-19} W/Hz^{1/2 } have been fabricated by SRON, which meet the sensitivity requirements for the far-infrared SAFARI instrument on space infrared telescope for cosmology and astrophysics. Our TES detector is based on a titanium/gold (Ti/Au) thermistor on a silicon nitride (SiN) island. The island is thermally linked with SiN legs to a silicon support structure at the bath temperature. The SiN legs are very thin (250 nm), narrow (500 nm), and long (above 300 {\\upmu } m); these dimensions are needed in leg-isolated bolometers to achieve the required level of sensitivity. In this paper, we describe the latest fabrication process for our TES bolometers with improved sensitivity.

Effects of Heat and Moisture Transfer Properties of Fabric on Heat Strain in Chemical Protective Ensembles

DTIC Science & Technology

2017-06-01

11 Table 1 Notation for fabric and ensemble resistances . .......................................... 13 Thermal manikin...Table 1 Notation for fabric and ensemble resistances .................................................. 13 Table 2 Weight reduction of CB garment...samples were tested on a Sweating Guarded Hot Plate (SGHP) to measure fabric thermal and evaporative resistance , respectively. The ensembles were tested

Low-resistive penetration in granular media

NASA Astrophysics Data System (ADS)

Darbois Texier, Baptiste; Ibarra, Alejandro; Melo, Fransisco

The quasi-static immersion of an intruder into a granular assembly requires a force that is several orders of magnitude larger than necessary in fluids under similar conditions. This occurs as a result of the progressive formation of a network composed of force chains, which simultaneously increase in size with intruder penetration. The present work shows that the resisting force for the immersion of an intruder into a granular material can be reduced by an order of magnitude with mechanical vibrations of small amplitude (A = 10 μm) and low frequency (f = 50-200 Hz). The effect of the vibrations characteristics and the intruder geometry on the drop of the resistive force were inspected experimentally. Thanks to flow visualizations, it has been shown that vibrations induce a local convection into the granular media leading to the modification of the network of force chains. Moreover, scaling arguments are developed in order to rationalize our observations and to predict under which circumstances the resistive force is reduced. Finally, the use of such a phenomenon in the animal kingdom and the technological world will be discussed.

BioWires: Conductive DNA Nanowires in a Computationally-Optimized, Synthetic Biological Platform for Nanoelectronic Fabrication

NASA Technical Reports Server (NTRS)

Vecchioni, Simon; Toomey, Emily; Capece, Mark C.; Rothschild, Lynn; Wind, Shalom

2017-01-01

DNA is an ideal template for a biological nanowire-it has a linear structure several atoms thick; it possesses addressable nucleobase geometry that can be precisely defined; and it is massively scalable into branched networks. Until now, the drawback of DNA as a conducting nanowire been, simply put, its low conductance. To address this deficiency, we extensively characterize a chemical variant of canonical DNA that exploits the affinity of natural cytosine bases for silver ions. We successfully construct chains of single silver ions inside double-stranded DNA, confirm the basic dC-Ag+-dC bond geometry and kinetics, and show length-tunability dependent on mismatch distribution, ion availability and enzyme activity. An analysis of the absorbance spectra of natural DNA and silver-binding, poly-cytosine DNA demonstrates the heightened thermostability of the ion chain and its resistance to aqueous stresses such as precipitation, dialysis and forced reduction. These chemically critical traits lend themselves to an increase in electrical conductivity of over an order of magnitude for 11-base silver-paired duplexes over natural strands when assayed by STM break junction. We further construct and implement a genetic pathway in the E. coli bacterium for the biosynthesis of highly ionizable DNA sequences. Toward future circuits, we construct a model of transcription network architectures to determine the most efficient and robust connectivity for cell-based fabrication, and we perform sequence optimization with a genetic algorithm to identify oligonucleotides robust to changes in the base-pairing energy landscape. We propose that this system will serve as a synthetic biological fabrication platform for more complex DNA nanotechnology and nanoelectronics with applications to deep space and low resource environments.

Low-temperature technique for thick film resist stabilization and curing

NASA Astrophysics Data System (ADS)

Minter, Jason P.; Wong, Selmer S.; Marlowe, Trey; Ross, Matthew F.; Narcy, Mark E.; Livesay, William R.

1999-06-01

For a range of thick film photoresist applications, including MeV ion implant processing, thin film head manufacturing, and microelectromechanical systems processing, there is a need for a low-temperature method for resist stabilization and curing. Traditional methods of stabilizing or curing resist films have relied on thermal cycling, which may not be desirable due to device temperature limitations or thermally-induced distortion of the resist features.

Fabrication of photovoltaic laser energy converterby MBE

NASA Technical Reports Server (NTRS)

Lu, Hamilton; Wang, Scott; Chan, W. S.

1993-01-01

A laser-energy converter, fabricated by molecular beam epitaxy (MBE), was developed. This converter is a stack of vertical p-n junctions connected in series by low-resistivity, lattice matched CoSi2 layers to achieve a high conversion efficiency. Special high-temperature electron-beam (e-beam) sources were developed especially for the MBE growth of the junctions and CoSi2 layers. Making use of the small (greater than 1.2 percent) lattice mismatch between CoSi2 and Si layers, high-quality and pinhole-free epilayers were achieved, providing a capability of fabricating all the junctions and connecting layers as a single growth process with one pumpdown. Well-defined multiple p-n junctions connected by CoSi2 layers were accomplished by employing a low growth temperature (greater than 700 C) and a low growth rate (less than 0.5 microns/hour). Producing negligible interdiffusion, the low growth temperature and rate also produced negligible pinholes in the CoSi2 layers. For the first time, a stack of three p-n junctions connected by two 10(exp -5) Ohm-cm CoSi2 layers was achieved, meeting the high conversion efficiency requirement. This process can now be optimized for high growth rate to form a practical converter with 10 p-n junctions in the stack.

Fabricating fiber Bragg gratings with two phase masks based on reconstruction-equivalent-chirp technique.

PubMed

Gao, Liang; Chen, Xiangfei; Xiong, Jintian; Liu, Shengchun; Pu, Tao

2012-01-30

Based on reconstruction-equivalent-chirp (REC) technique, a novel solution for fabricating low-cost long fiber Bragg gratings (FBGs) with desired properties is proposed and initially studied. A proof-of-concept experiment is demonstrated with two conventional uniform phase masks and a submicron-precision translation stage, successfully. It is shown that the original phase shift (OPS) caused by phase mismatch of the two phase masks can be compensated by the equivalent phase shift (EPS) at the ±1st channels of sampled FBGs, separately. Furthermore, as an example, a π phase-shifted FBG of about 90 mm is fabricated by using these two 50mm-long uniform phase masks based on the presented method.

UAV low-altitude remote sensing for precision weed management

USDA-ARS?s Scientific Manuscript database

Precision weed management, an application of precision agriculture, accounts for within-field variability of weed infestation and herbicide damage. Unmanned aerial vehicles (UAVs) provide a unique platform for remote sensing of field crops. They are more efficient and flexible than manned agricultur...

Development of a Prototype Low-Voltage Electron Beam Freeform Fabrication System

NASA Technical Reports Server (NTRS)

Watson, J. K.; Taminger, K. M.; Hafley, R. A.; Petersen, D. D.

2002-01-01

NASA's Langley Research Center and Johnson Space Center are developing a solid freeform fabrication system utilizing an electron beam energy source and wire feedstock. This system will serve as a testbed for exploring the influence of gravitational acceleration on the deposition process and will be a simplified prototype for future systems that may be deployed during long-duration space missions for assembly, fabrication, and production of structural and mechanical replacement components. Critical attributes for this system are compactness, minimal mass, efficiency in use of feedstock material, energy use efficiency, and safety. The use of a low-voltage (less than 15kV) electron beam energy source will reduce radiation so that massive shielding is not required to protect adjacent personnel. Feedstock efficiency will be optimized by use of wire, and energy use efficiency will be achieved by use of the electron beam energy source. This system will be evaluated in a microgravity environment using the NASA KC-135A aircraft.

Accuracy and precision of polyurethane dental arch models fabricated using a three-dimensional subtractive rapid prototyping method with an intraoral scanning technique

PubMed Central

Kim, Jae-Hong; Kim, Ki-Baek; Kim, Woong-Chul; Kim, Ji-Hwan

2014-01-01

Objective This study aimed to evaluate the accuracy and precision of polyurethane (PUT) dental arch models fabricated using a three-dimensional (3D) subtractive rapid prototyping (RP) method with an intraoral scanning technique by comparing linear measurements obtained from PUT models and conventional plaster models. Methods Ten plaster models were duplicated using a selected standard master model and conventional impression, and 10 PUT models were duplicated using the 3D subtractive RP technique with an oral scanner. Six linear measurements were evaluated in terms of x, y, and z-axes using a non-contact white light scanner. Accuracy was assessed using mean differences between two measurements, and precision was examined using four quantitative methods and the Bland-Altman graphical method. Repeatability was evaluated in terms of intra-examiner variability, and reproducibility was assessed in terms of inter-examiner and inter-method variability. Results The mean difference between plaster models and PUT models ranged from 0.07 mm to 0.33 mm. Relative measurement errors ranged from 2.2% to 7.6% and intraclass correlation coefficients ranged from 0.93 to 0.96, when comparing plaster models and PUT models. The Bland-Altman plot showed good agreement. Conclusions The accuracy and precision of PUT dental models for evaluating the performance of oral scanner and subtractive RP technology was acceptable. Because of the recent improvements in block material and computerized numeric control milling machines, the subtractive RP method may be a good choice for dental arch models. PMID:24696823

Accuracy and precision of polyurethane dental arch models fabricated using a three-dimensional subtractive rapid prototyping method with an intraoral scanning technique.

PubMed

Kim, Jae-Hong; Kim, Ki-Baek; Kim, Woong-Chul; Kim, Ji-Hwan; Kim, Hae-Young

2014-03-01

This study aimed to evaluate the accuracy and precision of polyurethane (PUT) dental arch models fabricated using a three-dimensional (3D) subtractive rapid prototyping (RP) method with an intraoral scanning technique by comparing linear measurements obtained from PUT models and conventional plaster models. Ten plaster models were duplicated using a selected standard master model and conventional impression, and 10 PUT models were duplicated using the 3D subtractive RP technique with an oral scanner. Six linear measurements were evaluated in terms of x, y, and z-axes using a non-contact white light scanner. Accuracy was assessed using mean differences between two measurements, and precision was examined using four quantitative methods and the Bland-Altman graphical method. Repeatability was evaluated in terms of intra-examiner variability, and reproducibility was assessed in terms of inter-examiner and inter-method variability. The mean difference between plaster models and PUT models ranged from 0.07 mm to 0.33 mm. Relative measurement errors ranged from 2.2% to 7.6% and intraclass correlation coefficients ranged from 0.93 to 0.96, when comparing plaster models and PUT models. The Bland-Altman plot showed good agreement. The accuracy and precision of PUT dental models for evaluating the performance of oral scanner and subtractive RP technology was acceptable. Because of the recent improvements in block material and computerized numeric control milling machines, the subtractive RP method may be a good choice for dental arch models.

Fabrication of precision optics using an imbedded reference surface

DOEpatents

Folta, James A.; Spiller, Eberhard

2005-02-01

The figure of a substrate is very precisely measured and a figured-correcting layer is provided on the substrate. The thickness of the figure-correcting layer is locally measured and compared to the first measurement. The local measurement of the figure-correcting layer is accomplished through a variety of methods, including interferometry and fluorescence or ultrasound measurements. Adjustments in the thickness of the figure-correcting layer are made until the top of the figure-correcting layer matches a desired figure specification.

Low-Temperature Flex Durability of Fabrics for Polar Sleds

DTIC Science & Technology

2014-10-06

friction owing to solar gain, so SPoT is systematically replacing older tan bladders with black ones constructed from similar polyurethane -coated...specimens of the existing bladder material (single-layer polyurethane - coated fabric) within a few cycles. Remarkably, the specimens could with- stand...fabrics: • Antarctic traverses should continue to use fuel bladders constructed from ATL-853C (black) polyurethane -coated fabric as supplied by Aero Tec

A Low-Cost Contact System to Assess Load Displacement Velocity in a Resistance Training Machine

PubMed Central

Buscà, Bernat; Font, Anna

2011-01-01

This study sought to determine the validity of a new system for assessing the displacement and average velocity within machine-based resistance training exercise using the Chronojump System. The new design is based on a contact bar and a simple, low-cost mechanism that detects the conductivity of electrical potentials with a precision chronograph. This system allows coaches to assess velocity to control the strength training process. A validation study was performed by assessing the concentric phase parameters of a leg press exercise. Output time data from the Chronojump System in combination with the pre-established range of movement was compared with data from a position sensor connected to a Biopac System. A subset of 87 actions from 11 professional tennis players was recorded and, using the two methods, average velocity and displacement variables in the same action were compared. A t-test for dependent samples and a correlation analysis were undertaken. The r value derived from the correlation between the Biopac System and the contact Chronojump System was >0.94 for all measures of displacement and velocity on all loads (p < 0.01). The Effect Size (ES) was 0.18 in displacement and 0.14 in velocity and ranged from 0.09 to 0.31 and from 0.07 to 0.34, respectively. The magnitude of the difference between the two methods in all parameters and the correlation values provided certain evidence of validity of the Chronojump System to assess the average displacement velocity of loads in a resistance training machine. Key points The assessment of speed in resistance machines is a valuable source of information for strength training. Many commercial systems used to assess velocity, power and force are expensive thereby preventing widespread use by coaches and athletes. The system is intended to be a low-cost device for assessing and controlling the velocity exerted on each repetition in any resistance training machine. The system could be easily adapted in any vertical

A low-cost contact system to assess load displacement velocity in a resistance training machine.

PubMed

Buscà, Bernat; Font, Anna

2011-01-01

This study sought to determine the validity of a new system for assessing the displacement and average velocity within machine-based resistance training exercise using the Chronojump System. The new design is based on a contact bar and a simple, low-cost mechanism that detects the conductivity of electrical potentials with a precision chronograph. This system allows coaches to assess velocity to control the strength training process. A validation study was performed by assessing the concentric phase parameters of a leg press exercise. Output time data from the Chronojump System in combination with the pre-established range of movement was compared with data from a position sensor connected to a Biopac System. A subset of 87 actions from 11 professional tennis players was recorded and, using the two methods, average velocity and displacement variables in the same action were compared. A t-test for dependent samples and a correlation analysis were undertaken. The r value derived from the correlation between the Biopac System and the contact Chronojump System was >0.94 for all measures of displacement and velocity on all loads (p < 0.01). The Effect Size (ES) was 0.18 in displacement and 0.14 in velocity and ranged from 0.09 to 0.31 and from 0.07 to 0.34, respectively. The magnitude of the difference between the two methods in all parameters and the correlation values provided certain evidence of validity of the Chronojump System to assess the average displacement velocity of loads in a resistance training machine. Key pointsThe assessment of speed in resistance machines is a valuable source of information for strength training.Many commercial systems used to assess velocity, power and force are expensive thereby preventing widespread use by coaches and athletes.The system is intended to be a low-cost device for assessing and controlling the velocity exerted on each repetition in any resistance training machine.The system could be easily adapted in any vertical

Precision Medicine and Men's Health.

PubMed

Mata, Douglas A; Katchi, Farhan M; Ramasamy, Ranjith

2017-07-01

Precision medicine can greatly benefit men's health by helping to prevent, diagnose, and treat prostate cancer, benign prostatic hyperplasia, infertility, hypogonadism, and erectile dysfunction. For example, precision medicine can facilitate the selection of men at high risk for prostate cancer for targeted prostate-specific antigen screening and chemoprevention administration, as well as assist in identifying men who are resistant to medical therapy for prostatic hyperplasia, who may instead require surgery. Precision medicine-trained clinicians can also let couples know whether their specific cause of infertility should be bypassed by sperm extraction and in vitro fertilization to prevent abnormalities in their offspring. Though precision medicine's role in the management of hypogonadism has yet to be defined, it could be used to identify biomarkers associated with individual patients' responses to treatment so that appropriate therapy can be prescribed. Last, precision medicine can improve erectile dysfunction treatment by identifying genetic polymorphisms that regulate response to medical therapies and by aiding in the selection of patients for further cardiovascular disease screening.

Analysis of Two Methods for Characterization of Flame Resistant Military Fabrics and Commercial Textile Fibers: Simultaneous DSC-TGA and Pyrolysis GCMS

DTIC Science & Technology

2014-04-04

military clothing and shelters. Thus, higher demands are put on the industry to improve the flame-resistant (FR) properties of high performance...polymers under development for military clothing and individual equipment and fabric shelters: (1) simultaneous differential scanning calorimetry...ANSI Std. Z39.18 GC/MS POLYMERS POLYMER FIBERS PROTECTIVE CLOTHING FIBERS

Heat resistant protective hand covering

NASA Technical Reports Server (NTRS)

Sidman, K. R.; Arons, I. J. (Inventor)

1984-01-01

The heat resistant, protective glove is made up of first and second shell sections which define a palm side and a backside, respectively. The first shell section is made of a twill wave fabric of a temperature-resistant aromatic polyamide fiber. The second shell section is made of a knitted fabric of a temperature-resistant aromatic polyamide fiber. The first and second shell sections are secured to one another, e.g., by sewing, to provide the desired glove configuration and an opening for insertion of the wearer's hand. The protective glove also includes a first liner section which is secured to and overlies the inner surface of the first shell section and is made of a felt fabric of a temperature-resistant aromatic polyamide fiber and has a flame resistant, elastomenic coating on the surface facing and overlying the inner surface of the first shell section.

Low- and High-Resistance Exercise: Long-Term Adherence and Motivation among Older Adults.

PubMed

Van Roie, Evelien; Bautmans, Ivan; Coudyzer, Walter; Boen, Filip; Delecluse, Christophe

2015-01-01

In terms of motivation and long-term adherence, low-resistance exercise might be more suitable for older adults than high-resistance exercise. However, more data are needed to support this claim. The objective was to investigate the effect of low- and high-resistance exercise protocols on long-term adherence and motivation. This study was designed as an exploratory 24-week follow-up of a randomized 12-week resistance training intervention in older adults. Participants were free to decide whether or not they continued resistance training at their own expense following the intervention. Fifty-six older adults were randomly assigned to HIGH [2 × 10-15 repetitions at 80% of one repetition maximum (1RM)], LOW (1 × 80-100 repetitions at 20% of 1RM), or LOW+ (1 × 60 repetitions at 20% of 1RM + 1 × 10-20 repetitions at 40% 1RM). Motivation, self-efficacy and the perceived barriers for continuing resistance exercise were measured after cessation of each supervised intervention and at follow-up, while long-term adherence was probed retrospectively at follow-up. Participants reported high levels of self-determined motivation before, during, and after the supervised intervention, with no differences between groups (p > 0.05). Nevertheless, only few participants continued strength training after the intervention: 17% in HIGH, 21% in LOW+, and 11% in LOW (p > 0.05). The most commonly reported barriers for continuing resistance exercise were perceived lack of time (46%), being more interested in other physical activities (40%), seasonal reasons (40%), and financial cost (28%). The results suggest no difference in long-term adherence after the end of a supervised exercise intervention at high or low external resistances. Long-term adherence was limited despite high levels of self-determined motivation during the interventions. These findings highlight the importance of further research on developing strategies to overcome barriers of older adults to adhere to resistance

A pressure-polishing set-up to fabricate patch pipettes that seal on virtually any membrane, yielding low access resistance and efficient intracellular perfusion.

PubMed

Benedusi, Mascia; Aquila, Marco; Milani, Alberto; Rispoli, Giorgio

2011-11-01

When performing whole-cell configuration recordings, it is important to minimize series resistance to reduce the time constant of charging the cell membrane capacitance and to reduce error in membrane potential control. To this end, an existing method was improved by widening the patch pipette shank through the calibrated combination of heat and air pressure. The heat was produced by passing current through a filament that was shaped appropriately to ensure a homogeneous heating of the pipette shank. Pressurized air was applied to the lumen of a pipette, pulled from a borosilicate glass microcap, via the pressure port of a modified commercial holder. The pipette reshaping was viewed on an LCD monitor connected to a contrast-intensified CCD camera and coupled to a modified bright-field stereomicroscope. By appropriately regulating the timing of air pressure and the application of heating, the pipette shank and, independently, the tip opening diameter were widened as desired. The methods illustrated here to fabricate and use the patch pipettes, using just one glass type, allowed the sealing of a wide variety of cell types isolated from different amphibian, reptilian, fish, and mammalian tissues as well as a variety of artificial membranes made with many different lipid mixtures. The access resistance yielded by pressure-polished pipettes was approximately one-fourth the size of the one attained with conventional pipettes; besides improving the electrical recordings, this minimized intracellular ion accumulation or depletion as well. Enlarged shank geometry allowed for fast intracellular perfusion as shown by fluorescence imaging, also via pulled quartz or plastic tubes, which could be inserted very close to the pipette tip.

Investigation of low-cost fabrication of ablative heat shields

NASA Technical Reports Server (NTRS)

Massions, V. P.; Mach, R. W.

1973-01-01

The fabrication, testing, and evaluation of materials and techniques employed in the fabrication of ablative heat shield panels are described. Results of this effort show projected reductions in labor man-hours for dielectric curing of panels when compared to panels molded in a steam-heated press. In addition, panels were fabricated with more than one density within the cross-section. These dual-density panels show significant weight and cost reduction potentials.

Superhydrophobic copper surfaces fabricated by fatty acid soaps in aqueous solution for excellent corrosion resistance

NASA Astrophysics Data System (ADS)

Xu, Wenlong; Hu, Yuanyuan; Bao, Wenda; Xie, Xiaoyu; Liu, Yiran; Song, Aixin; Hao, Jingcheng

2017-03-01

A simple and safe one-step immersion method was developed to obtain the stable superhydrophobic copper surfaces with excellent corrosion resistance ability using fatty acids in water-medium instead of ethanol. An organic alkali, N,N-dimethylcyclohexylamine (DMCHA), was chosen to solve the poor solubility of fatty acids in water and the high Krafft point of carboxylate salts with inorganic counterions. The superhydrophobic property can be realized in a much quicker process (7.5 min) in aqueous solution than in ethanol (more than 2 d), which is universally feasible for the fabrication of superhydrophobic metal surfaces in industry scale, thereby greatly increasing the safety in industrial manufacture.

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.

Can Energy Cost During Low-Intensity Resistance Exercise be Predicted by the OMNI-RES Scale?

PubMed Central

Vianna, Jefferson M.; Reis, Victor M.; Saavedra, Francisco; Damasceno, Vinicius; Silva, Sérgio G.; Goss, Fredric

2011-01-01

The aim of the present study was to assess the precision of the OMNI-RES scale to predict energy cost (EC) at low intensity in four resistance exercises (RE). 17 male recreational body builders (age = 26.6 ± 4.9 years; height = 177.7 ± 0.1 cm; body weight = 79.0 ± 11.1 kg and percent body fat = 10.5 ± 4.6%) served as subjects. Initially tests to determine 1RM for four resistance exercises (bench press, half squat, lat pull down and triceps extension) were administered. Subjects also performed resistance exercise at 12, 16, 20, and 24% of 1RM at a rate of 40 bpm until volitional exhaustion. Oxygen uptake (VO2) and rate of perceived exertion (RPE) using the OMNI-RES were obtained during and after all RE. EC was calculated using VO2 and the caloric values of VO2 for non-protein RER. Regression analyses were performed for every RE, using EC as the dependent and RPE as the predictor variable. The triceps extension, lat pull down and bench press, RPE correlated strongly with EC (R > 0.97) and predicted EC with a error of less than 0.2 kcal.min−1. In conclusion, RPE using the OMNI-RES scale can be considered as an accurate indicator of EC in the bench press, lat pull down and triceps extension performed by recreational bodybuilders, provided lower intensities are used (up to 24% of 1-RM) and provided each set of exercise is performed for the maximal sustainable duration. It would be interesting in future studies to consider having the subjects exercise at low intensities for longer durations than those in the present study. PMID:23486188

All plastic ultra-small size imaging lens unit fabrication and evaluation for endoscope

NASA Astrophysics Data System (ADS)

Ishii, Kenta; Okamoto, Dai; Ushio, Makoto; Tai, Hidetoshi; Nishihara, Atsuhiko; Tokuda, Kimio; Kawai, Shinsuke; Kitagawa, Seiichiro

2017-02-01

There is demand for small-size lens units for endoscope and industrial applications. Polished glass lenses with a diameter of 1 - 2mm exist, however plastic lenses similar in size are not commonplace. For low-cost, light-weight, and mass production, plastic lens fabrication is extremely beneficial. Especially, in the medical field, there is strong demand for disposable lens unit for endoscopes which prevent contamination due to reuse of the lens. Therefore, high mass producible and low cost becomes increasingly important. This paper reports our findings on injection-molded ultra-small size plastic lens units with a diameter of 1.3mm and total thickness of 1.4mm. We performed optical design, injection molding, and lens unit assembly for injection moldable, high imaging performance ultra-small sized lens units. We prioritize a robust product design, considering injection molding properties and lens unit assembly, with feedback from molding simulations reflected into the optical design. A mold capable of high precision lens positioning is used to fabricate the lenses and decrease the variability of the assembly. The geometric dimensions of the resulting lenses, are measured and used in the optical simulation to validate the optical performance, and a high agreement is reported. The injection molding of the lens and the assembly of the lens unit is performed with high precision, and results in high optical performance.

On the design and fabrication of nanostructures and devices

NASA Astrophysics Data System (ADS)

Wei, Wei

Nanotechnology is emerging into a new frontier in science and technology with potential impact on every aspect of human life. One of the major breakthroughs in today's nanotechnology is the discovery and preparation of new classes of nanomaterials and nanostructures. A large number of nanomaterials and nanostructures are synthesized and characterized with either new or profoundly enhanced properties or phenomena. However, there are several major challenges ahead need to be overcome before any substantial benefits can be brought to the market. One of the challenges that we need to address today is how to effectively integrate useful nanomaterials and nanostrucrures into functional devices and systems. Our mother nature gives us a classic example of how living organisms are built. Starting from a single cell, through its division and growth, it can self-assemble and become functional tissues and organs. Similar self-assemble approach has been adopted as a nano-fabrication technique to assemble nanomaterials and nanostructures into functional nanodevices. This technique has advantages of high precision and nanometer scale resolution. However, it requires a lot of effort to construct a single device and since the properties of individual nanostructures can be different, the fabricated devices may have different properties. In this dissertation, we design and fabricate nanostructures and devices using novel microfabrication techniques. In the first part of the dissertation, the design and fabrication of a variety of nanostructures, such as metal nanowires array, polymer nanowells, and nanostructured surfaces are discussed. In the second part, carbon nanotubes as a novel material has been explored as an example to demonstrate the integration of nanomaterials with novel microfabrication techniques to form a functional device. First, a resistive heating technique is developed to grow carbon nanotubes in localized regions, such as a nichrome heating coil. Then, MEMS micro

High volume fabrication of laser targets using MEMS techniques

NASA Astrophysics Data System (ADS)

Spindloe, C.; Arthur, G.; Hall, F.; Tomlinson, S.; Potter, R.; Kar, S.; Green, J.; Higginbotham, A.; Booth, N.; Tolley, M. K.

2016-04-01

The latest techniques for the fabrication of high power laser targets, using processes developed for the manufacture of Micro-Electro-Mechanical System (MEMS) devices are discussed. These laser targets are designed to meet the needs of the increased shot numbers that are available in the latest design of laser facilities. Traditionally laser targets have been fabricated using conventional machining or coarse etching processes and have been produced in quantities of 10s to low 100s. Such targets can be used for high complexity experiments such as Inertial Fusion Energy (IFE) studies and can have many complex components that need assembling and characterisation with high precision. Using the techniques that are common to MEMS devices and integrating these with an existing target fabrication capability we are able to manufacture and deliver targets to these systems. It also enables us to manufacture novel targets that have not been possible using other techniques. In addition, developments in the positioning systems that are required to deliver these targets to the laser focus are also required and a system to deliver the target to a focus of an F2 beam at 0.1Hz is discussed.

Microfabrication: LIGA-X and applications

NASA Astrophysics Data System (ADS)

Kupka, R. K.; Bouamrane, F.; Cremers, C.; Megtert, S.

2000-09-01

X-ray LIGA (Lithography, Electrogrowth, Moulding) is one of today's key technologies in microfabrication and upcoming modern (meso)-(nano) fabrication, already used and anticipated for micromechanics (micromotors, microsensors, spinnerets, etc.), micro-optics, micro-hydrodynamics (fluidic devices), microbiology, in medicine, in biology, and in chemistry for microchemical reactors. It compares to micro-electromechanical systems (MEMS) technology, offering a larger, non-silicon choice of materials and better inherent precision. X-ray LIGA relies on synchrotron radiation to obtain necessary X-ray fluxes and uses X-ray proximity printing. Inherent advantages are its extreme precision, depth of field and very low intrinsic surface roughness. However, the quality of fabricated structures often depends on secondary effects during exposure and effects like resist adhesion. UV-LIGA, relying on thick UV resists is an alternative for projects requiring less precision. Modulating the spectral properties of synchrotron radiation, different regimes of X-ray lithography lead to (a) the mass-fabrication of classical nanostructures, (b) the fabrication of high aspect ratio nanostructures (HARNST), (c) the fabrication of high aspect ratio microstructures (HARMST), and (d) the fabrication of high aspect ratio centimeter structures (HARCST). Reviewing very recent activities around X-ray LIGA, we show the versatility of the method, obviously finding its region of application there, where it is best and other competing microtechnologies are less advantageous. An example of surface-based X-ray and particle lenses (orthogonal reflection optics (ORO)) made by X-ray LIGA is given.

Fabrication of Nanovoid-Imbedded Bismuth Telluride with Low Dimensional System

NASA Technical Reports Server (NTRS)

Chu, Sang-Hyon (Inventor); Choi, Sang H. (Inventor); Kim, Jae-Woo (Inventor); Park, Yeonjoon (Inventor); Elliott, James R. (Inventor); King, Glen C. (Inventor); Stoakley, Diane M. (Inventor)

2013-01-01

A new fabrication method for nanovoids-imbedded bismuth telluride (Bi--Te) material with low dimensional (quantum-dots, quantum-wires, or quantum-wells) structure was conceived during the development of advanced thermoelectric (TE) materials. Bismuth telluride is currently the best-known candidate material for solid-state TE cooling devices because it possesses the highest TE figure of merit at room temperature. The innovative process described here allows nanometer-scale voids to be incorporated in Bi--Te material. The final nanovoid structure such as void size, size distribution, void location, etc. can be also controlled under various process conditions.

Near-Net Shape Fabrication Using Low-Cost Titanium Alloy Powders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dr. David M. Bowden; Dr. William H. Peter

2012-03-31

The use of titanium in commercial aircraft production has risen steadily over the last half century. The aerospace industry currently accounts for 58% of the domestic titanium market. The Kroll process, which has been used for over 50 years to produce titanium metal from its mineral form, consumes large quantities of energy. And, methods used to convert the titanium sponge output of the Kroll process into useful mill products also require significant energy resources. These traditional approaches result in product forms that are very expensive, have long lead times of up to a year or more, and require costly operationsmore » to fabricate finished parts. Given the increasing role of titanium in commercial aircraft, new titanium technologies are needed to create a more sustainable manufacturing strategy that consumes less energy, requires less material, and significantly reduces material and fabrication costs. A number of emerging processes are under development which could lead to a breakthrough in extraction technology. Several of these processes produce titanium alloy powder as a product. The availability of low-cost titanium powders may in turn enable a more efficient approach to the manufacture of titanium components using powder metallurgical processing. The objective of this project was to define energy-efficient strategies for manufacturing large-scale titanium structures using these low-cost powders as the starting material. Strategies include approaches to powder consolidation to achieve fully dense mill products, and joining technologies such as friction and laser welding to combine those mill products into near net shape (NNS) preforms for machining. The near net shape approach reduces material and machining requirements providing for improved affordability of titanium structures. Energy and cost modeling was used to define those approaches that offer the largest energy savings together with the economic benefits needed to drive implementation

Investigation on low velocity impact resistance of SMA composite material

NASA Astrophysics Data System (ADS)

Hu, Dianyin; Zhang, Long; Wang, Rongqiao; Zhang, Xiaoyong

2016-04-01

A method to improve low velocity impact resistance of aeroengine composite casing using shape memory alloy's properties of shape memory(SM) and super-elasticity(SE) is proposed in this study. Firstly, a numerical modeling of SMA reinforced composite laminate under low velocity impact load with impact velocity of 10 m/s is established based on its constitutive model implemented by the VUMAT subroutine of commercial software ABAQUS. Secondly, the responses of SMA composite laminate including stress and deflection distributions were achieved through transient analysis under low velocity impact load. Numerical results show that both peak stress and deflection values of SMA composite laminate are less than that without SMA, which proves that embedding SMA into the composite structure can effectively improve the low velocity impact performance of composite structure. Finally, the influence of SM and SE on low velocity impact resistance is quantitatively investigated. The values of peak stress and deflection of SMA composite based on SM property decrease by 18.28% and 9.43% respectively, compared with those without SMA, instead of 12.87% and 5.19% based on SE. In conclusion, this proposed model described the impact damage of SMA composite structure and turned to be a more beneficial method to enhance the impact resistance by utilizing SM effect.

Low prevalence of primary HIV resistance in western Massachusetts.

PubMed

Iarikov, Dmitri E; Irizarry-Acosta, Melina; Martorell, Claudia; Hoffman, Robert P; Skiest, Daniel J

2010-01-01

Most studies of primary antiretroviral (ARV) resistance have been conducted in large metropolitan areas with reported rates of 8% to 25%. We collected data on 99 HIV-1-infected antiretroviral-naive patients from several sites in Springfield, MA, who underwent genotypic resistance assay between 2004 and 2008. Only major resistance mutations per International AIDS Society-USA (IAS-USA) drug resistance mutations list were considered. The prevalence of resistance was 5% (5 of 99). Three patients had one nonnucleoside reverse transcriptase inhibitor (NNRTI) mutation: 103N, 103N, and 190A, 1 patient had a protease inhibitor (PI) mutation: 90M; and 1 patient had 3-class resistance with NNRTI: 181C, 190A, PI: 90M, and nucleoside analogue reverse transcriptase inhibitor (NRTI): 41L, 210W. Mean time from HIV diagnosis to resistance testing was shorter in patients with resistance versus those without: 9 (range 0.3-42 months) versus 27 (range 0.1-418 months), P = .11. There was a trend to lower mean CD4 count in those with resistance, 170 versus 318 cells/mm(3), P = .06. No differences were noted in gender, age, HIV risk category, or HIV RNA level. The low prevalence of primary resistance may be explained by differences in demographic and risk factors or may reflect the time from infection to resistance testing. Our findings emphasize the importance of continued resistance surveillance.

Analytical assessment of woven fabrics under vertical stabbing - The role of protective clothing.

PubMed

Hejazi, Sayyed Mahdi; Kadivar, Nastaran; Sajjadi, Ali

2016-02-01

Knives are being used more commonly in street fights and muggings. Therefore, this work presents an analytical model for woven fabrics under vertical stabbing loads. The model is based on energy method and the fabric is assumed to be unidirectional comprised of N layers. Thus, the ultimate stab resistance of fabric was determined based on structural parameters of fabric and geometrical characteristics of blade. Moreover, protective clothing is nowadays considered as a strategic branch in technical textile industry. The main idea of the present work is improving the stab resistance of woven textiles by using metal coating method. In the final, a series of vertical stabbing tests were conducted on cotton, polyester and polyamide fabrics. Consequently, it was found that the model predicts with a good accuracy the ultimate stab resistance of the sample fabrics. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Simplified Fabrication of Helical Copper Antennas

NASA Technical Reports Server (NTRS)

Petro, Andrew

2006-01-01

A simplified technique has been devised for fabricating helical antennas for use in experiments on radio-frequency generation and acceleration of plasmas. These antennas are typically made of copper (for electrical conductivity) and must have a specific helical shape and precise diameter.

Facile fabrication of CNT-based chemical sensor operating at room temperature

NASA Astrophysics Data System (ADS)

Sheng, Jiadong; Zeng, Xian; Zhu, Qi; Yang, Zhaohui; Zhang, Xiaohua

2017-12-01

This paper describes a simple, low cost and effective route to fabricate CNT-based chemical sensors, which operate at room temperature. Firstly, the incorporation of silk fibroin in vertically aligned CNT arrays (CNTA) obtained through a thermal chemical vapor deposition (CVD) method makes the direct removal of CNT arrays from substrates without any rigorous acid or sonication treatment feasible. Through a simple one-step in situ polymerization of anilines, the functionalization of CNT arrays with polyaniline (PANI) significantly improves the sensing performance of CNT-based chemical sensors in detecting ammonia (NH3) and hydrogen chloride (HCl) vapors. Chemically modified CNT arrays also show responses to organic vapors like menthol, ethyl acetate and acetone. Although the detection limits of chemically modified CNT-based chemical sensors are of the same orders of magnitudes reported in previous studies, these CNT-based chemical sensors show advantages of simplicity, low cost and energy efficiency in preparation and fabrication of devices. Additionally, a linear relationship between the relative sensitivity and concentration of analyte makes precise estimations on the concentrations of trace chemical vapors possible.

GaN on Diamond with Ultra-Low Thermal Barrier Resistance

DTIC Science & Technology

2016-03-31

GaN-on-Diamond with Ultra-Low Thermal Barrier Resistance Xing Gu1, Cathy Lee1, Jinqiao Xie1, Edward Beam1, Michael Becker2, Timothy A. Grotjohn2...Bristol BS8 1TL, UK Abstract: We investigated the effective thermal boundary resistance (TBReff) of GaN-on-Diamond interfaces for diamond growth... thermal boundary resistance; TBReff , interfacial layers; high density dielectric Introduction While GaN-based RF transistors, typically on SiC

Conductive pathway on cotton fabric created using solution with silver organometallic compound

NASA Astrophysics Data System (ADS)

Campbell, Eric E.; He, Ruijian; Mayer, Michael

2017-10-01

A knitted cotton fabric is made conductive by thermal deposition of an organometallic silver compound (OSC). For the thermal process, the fabric was soaked with the OSC liquid and heated to 225 °C for 4 min. The cured state of the OSC is determined by the stabilization in the electrical resistance. The resulting silver metallization is shaped as nanoparticles and a continuous film. A typical resistance of a 10 cm  ×  1.5 cm metallized strip made with 1.9 ml OSC is 1.70 Ω. Various other resistance levels were achieved. A higher volume of OSC provided a lower electrical resistance for the metallized conductive path but increased its stiffness. Lower resistance was achieved by increasing the number of repeat coatings while keeping the OSC volume constant. The resistance decreased when the OSC coated fabric was elongated, an effect similar to negative piezoresistivity. A resistance of initially 0.34 Ω decreased to a minimum of 0.29 Ω at 10% elongation under repeated stretching and relaxation cycling. The metallization method reported here can be suitable for applications in the field know as technical textiles, electronic textiles (e-textiles), wearable electronics, functional garments, or smart fabrics.

Fabrication of low-crystalline carbonate apatite foam bone replacement based on phase transformation of calcite foam.

PubMed

Maruta, Michito; Matsuya, Shigeki; Nakamura, Seiji; Ishikawa, Kunio

2011-01-01

Carbonate apatite (CO(3)Ap) foam may be an ideal bone substitute as it is sidelined to cancellous bone with respect to its chemical composition and structure. However, CO(3)Ap foam fabricated using α-tricalcium phosphate foam showed limited mechanical strength. In the present study, feasibility of the fabrication of calcite which could be a precursor of CO(3)Ap was studied. Calcite foam was successfully fabricated by the so-called "ceramic foam" method using calcium hydroxide coated polyurethane foam under CO(2)+O(2) atmosphere. Then the calcite foam was immersed in Na(2)HPO(4) aqueous solution for phase transformation based on dissolution-precipitation reaction. When CaO-free calcite foam was immersed in Na(2)HPO(4) solution, low-crystalline CO(3)Ap foam with 93-96% porosity and fully interconnected porous structure was fabricated. The compressive strength of the foam was 25.6 ± 6 kPa. In light of these results, we concluded that the properties of the precursor foam were key factors for the fabrication of CO(3)Ap foams.

Fracture resistance and failure mode of posterior fixed dental prostheses fabricated with two zirconia CAD/CAM systems

PubMed Central

López-Suárez, Carlos; Gonzalo, Esther; Peláez, Jesús; Rodríguez, Verónica

2015-01-01

Background In recent years there has been an improvement of zirconia ceramic materials to replace posterior missing teeth. To date little in vitro studies has been carried out on the fracture resistance of zirconia veneered posterior fixed dental prostheses. This study investigated the fracture resistance and the failure mode of 3-unit zirconia-based posterior fixed dental prostheses fabricated with two CAD/CAM systems. Material and Methods Twenty posterior fixed dental prostheses were studied. Samples were randomly divided into two groups (n=10 each) according to the zirconia ceramic analyzed: Lava and Procera. Specimens were loaded until fracture under static load. Data were analyzed using Wilcoxon´s rank sum test and Wilcoxon´s signed-rank test (P<0.05). Results Partial fracture of the veneering porcelain occurred in 100% of the samples. Within each group, significant differences were shown between the veneering and the framework fracture resistance (P=0.002). The failure occurred in the connector cervical area in 80% of the cases. Conclusions All fracture load values of the zirconia frameworks could be considered clinically acceptable. The connector area is the weak point of the restorations. Key words:Fixed dental prostheses, zirconium-dioxide, zirconia, fracture resistance, failure mode. PMID:26155341

Fabrication of mitigation pits for improving laser damage resistance in dielectric mirrors by femtosecond laser machining

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolfe, Justin E.; Qiu, S. Roger; Stolz, Christopher J.

2011-03-20

Femtosecond laser machining is used to create mitigation pits to stabilize nanosecond laser-induced damage in multilayer dielectric mirror coatings on BK7 substrates. In this paper, we characterize features and the artifacts associated with mitigation pits and further investigate the impact of pulse energy and pulse duration on pit quality and damage resistance. Our results show that these mitigation features can double the fluence-handling capability of large-aperture optical multilayer mirror coatings and further demonstrate that femtosecond laser macromachining is a promising means for fabricating mitigation geometry in multilayer coatings to increase mirror performance under high-power laser irradiation.

FECAL SOURCE TRACKING BY ANTIBIOTIC RESISTANCE ANALYSIS ON A WATERSHED EXHIBITING LOW RESISTANCE

EPA Science Inventory

The ongoing development of microbial source tracking has made it possible to identify contamination sources with varying accuracy, depending on the method used. The purpose of this study was done to test the efficiency of the antibiotic resistance analysis (ARA) method under low ...

Low resistivity contacts to YBa2Cu3O(7-x) superconductors

NASA Technical Reports Server (NTRS)

Hsi, Chi-Shiung; Haertling, Gene H.

1991-01-01

Silver, gold, platinum, and palladium metals were investigated as electroding materials for the YBa2Cu3O(7-x) superconductors. Painting, embedding, and melting techniques were used to apply the electrodes. Contact resistivities were determined by: (1) type of electrode; (2) firing conditions; and (3) application method. Electrodes fired for long times exhibited lower contact resistivities than those fired for short times. Low-resistivity contacts were found for silver and gold electrodes. Silver, which made good ohmic contact to the YBa2Cu3O(7-x) superconductor with low contact resistivities was found to be the best electroding material among the materials evaluated in this investigation.

Ultra-low contact resistance in graphene devices at the Dirac point

NASA Astrophysics Data System (ADS)

Anzi, Luca; Mansouri, Aida; Pedrinazzi, Paolo; Guerriero, Erica; Fiocco, Marco; Pesquera, Amaia; Centeno, Alba; Zurutuza, Amaia; Behnam, Ashkan; Carrion, Enrique A.; Pop, Eric; Sordan, Roman

2018-04-01

Contact resistance is one of the main factors limiting performance of short-channel graphene field-effect transistors (GFETs), preventing their use in low-voltage applications. Here we investigated the contact resistance between graphene grown by chemical vapor deposition (CVD) and different metals, and found that etching holes in graphene below the contacts consistently reduced the contact resistance, down to 23 Ω \\cdot μ m with Au contacts. This low contact resistance was obtained at the Dirac point of graphene, in contrast to previous studies where the lowest contact resistance was obtained at the highest carrier density in graphene (here 200 Ω \\cdot μ m was obtained under such conditions). The ‘holey’ Au contacts were implemented in GFETs which exhibited an average transconductance of 940 S m-1 at a drain bias of only 0.8 V and gate length of 500 nm, which out-perform GFETs with conventional Au contacts.

Fabricating Copper Nanotubes by Electrodeposition

NASA Technical Reports Server (NTRS)

Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

2009-01-01

Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

Fabrication of a biomimetic elastic intervertebral disk scaffold using additive manufacturing.

PubMed

Whatley, Benjamin R; Kuo, Jonathan; Shuai, Cijun; Damon, Brooke J; Wen, Xuejun

2011-03-01

A custom-designed three-dimensional additive manufacturing device was developed to fabricate scaffolds for intervertebral disk (IVD) regeneration. This technique integrated a computer with a device capable of 3D movement allowing for precise motion and control over the polymer scaffold resolution. IVD scaffold structures were designed using computer-aided design to resemble the natural IVD structure. Degradable polyurethane (PU) was used as an elastic scaffold construct to mimic the elastic nature of the native IVD tissue and was deposited at a controlled rate using ultra-fine micropipettes connected to a syringe pump. The elastic PU was extruded directly onto a collecting substrate placed on a freezing stage. The three-dimensional movement of the computer-controlled device combined with the freezing stage enabled precise control of polymer deposition using extrusion. The addition of the freezing stage increased the polymer solution viscosity and hardened the polymer solution as it was extruded out of the micropipette tip. This technique created scaffolds with excellent control over macro- and micro-structure to influence cell behavior, specifically for cell adhesion, proliferation, and alignment. Concentric lamellae were printed at a high resolution to mimic the native shape and structure of the IVD. Seeded cells aligned along the concentric lamellae and acquired cell morphology similar to native tissue in the outer portion of the IVD. The fabricated scaffolds exhibited elastic behavior during compressive and shear testing, proving that the scaffolds could support loads with proper fatigue resistance without permanent deformation. Additionally, the mechanical properties of the scaffolds were comparable to those of native IVD tissue.

Two-photon polymerization for fabrication of biomedical devices

NASA Astrophysics Data System (ADS)

Ovsianikov, Aleksandr; Doraiswamy, Anand; Narayan, R.; Chichkov, B. N.

2007-01-01

Two-photon polymerization (2PP) is a novel technology which allows the fabrication of complex three-dimensional (3D) microstructures and nanostructures. The number of applications of this technology is rapidly increasing; it includes the fabrication of 3D photonic crystals [1-4], medical devices, and tissue scaffolds [5-6]. In this contribution, we discuss current applications of 2PP for microstructuring of biomedical devices used in drug delivery. While in general this sector is still dominated by oral administration of drugs, precise dosing, safety, and convenience are being addressed by transdermal drug delivery systems. Currently, main limitations arise from low permeability of the skin. As a result, only few types of pharmacological substances can be delivered in this manner [7]. Application of microneedle arrays, whose function is to help overcome the barrier presented by the epidermis layer of the skin, provides a very promising solution. Using 2PP we have fabricated arrays of hollow microneedles with different geometries. The effect of microneedle geometry on skin penetration is examined. Our results indicate that microneedles created using 2PP technique are suitable for in vivo use, and for integration with the next generation of MEMS- and NEMS-based drug delivery devices.

Unscented predictive variable structure filter for satellite attitude estimation with model errors when using low precision sensors

NASA Astrophysics Data System (ADS)

Cao, Lu; Li, Hengnian

2016-10-01

For the satellite attitude estimation problem, the serious model errors always exist and hider the estimation performance of the Attitude Determination and Control System (ACDS), especially for a small satellite with low precision sensors. To deal with this problem, a new algorithm for the attitude estimation, referred to as the unscented predictive variable structure filter (UPVSF) is presented. This strategy is proposed based on the variable structure control concept and unscented transform (UT) sampling method. It can be implemented in real time with an ability to estimate the model errors on-line, in order to improve the state estimation precision. In addition, the model errors in this filter are not restricted only to the Gaussian noises; therefore, it has the advantages to deal with the various kinds of model errors or noises. It is anticipated that the UT sampling strategy can further enhance the robustness and accuracy of the novel UPVSF. Numerical simulations show that the proposed UPVSF is more effective and robustness in dealing with the model errors and low precision sensors compared with the traditional unscented Kalman filter (UKF).

Fabrication of vanadium dioxide polycrystalline films with higher temperature coefficient of resistance

NASA Astrophysics Data System (ADS)

Li, Jinhua; Yuan, Ningyi; Jiang, Meiping; Kun, Li

2011-08-01

Vanadium Dioxide Polycrystalline Films with High Temperature Coefficient of Resistance(TCR) were fabricated by modified Ion Beam Enhanced Deposition(IBED) method. The TCR of the Un-doping VO2 was about -4%/K at room temperature after appropriate thermal annealing. The XRD results clearly showed that IBED polycrystalline VO2 films had a single [002] orientation of VO2(M). The TCR of 5at.%W and 7at.% Ta doped Vanadium Dioxide Polycrystalline Films were high up to -18%/K and -12%/K at room temperature, respectively. Using 7at.% Ta and 2at.% Ti co-doping, the TCR of the co-doped vanadium oxide film was -7%/K and without hysteresis during temperature increasing and decresing from 0-80°C. It should indicate that the W-doped vanadium dioxide films colud be used for high sensing IR detect and the Ta/Ti co-doped film without hysteresis is suitable for infrarid imaging application.

Conformal chemically resistant coatings for microflow devices

DOEpatents

Folta, James A.; Zdeblick, Mark

2003-05-13

A process for coating the inside surfaces of silicon microflow devices, such as electrophoresis microchannels, with a low-stress, conformal (uniform) silicon nitride film which has the ability to uniformly coat deeply-recessed cavities with, for example, aspect ratios of up to 40:1 or higher. The silicon nitride coating allows extended exposure to caustic solutions. The coating enables a microflow device fabricated in silicon to be resistant to all classes of chemicals: acids, bases, and solvents. The process involves low-pressure (vacuum) chemical vapor deposition. The ultra-low-stress silicon nitride deposition process allows 1-2 .mu.m thick films without cracks, and so enables extended chemical protection of a silicon microflow device against caustics for up to 1 year. Tests have demonstrated the resistance of the films to caustic solutions at both ambient and elevated temperatures to 65.degree. C.

Low-cost precision rotary index calibration

NASA Astrophysics Data System (ADS)

Ng, T. W.; Lim, T. S.

2005-08-01

The traditional method for calibrating angular indexing repeatability of rotary axes on machine tools and measuring equipment is with a precision polygon (usually 12 sided) and an autocollimator or angular interferometer. Such a setup is typically expensive. Here, we propose a far more cost-effective approach that uses just a laser, diffractive optical element, and CCD camera. We show that significantly high accuracies can be achieved for angular index calibration.

Inexpensive, rapid fabrication of polymer-film microfluidic autoregulatory valve for disposable microfluidics.

PubMed

Zhang, Xinjie; Zhu, Zhixian; Ni, Zhonghua; Xiang, Nan; Yi, Hong

2017-06-01

This work presents the fabrication of a microfluidic autoregulatory valve which is composed of several layers of thin polymer films (i.e., polyvinyl chloride (PVC), polyethylene terephthalate (PET) double-sided tape, and polydimethylsiloxane (PDMS)). Briefly, pulsed UV laser is employed to cut the microstructures of through grooves or holes in the thermoplastic polymer films, and then the polymer-film valves are precisely assembled through laminating the PDMS membranes to the thermoplastic polymer films through the roll-lamination method. The effective bonding between the PVC film and the PDMS membrane is realized using the planar seal method, and the valve is sandwiched and compressed by a home-made housing to achieve the good seal effect. Then, the flow performances of the prototype valve are examined, and constant flow autoregulation is realized under the static or dynamic test pressures. The long-term response of the valve is also studied and minimum flow-rate decrements are found over a long actuation time. The fabrication method proposed in this work is successful for the low-cost and fast prototyping of the polymer-film valve. We believe our method will also be broadly applicable for fabrication of other low-cost and disposable polymer-film microfluidic devices.

Batch Fabrication of Ultrasensitive Carbon Nanotube Hydrogen Sensors with Sub-ppm Detection Limit.

PubMed

Xiao, Mengmeng; Liang, Shibo; Han, Jie; Zhong, Donglai; Liu, Jingxia; Zhang, Zhiyong; Peng, Lianmao

2018-04-27

Carbon nanotube (CNT) has been considered as an ideal channel material for building highly sensitive gas sensors. However, the reported H 2 sensors based on CNT always suffered from the low sensitivity or low production. We developed the technology to massively fabricate ultra-highly sensitive H 2 sensors based on solution derived CNT network through comprehensive optimization of the CNT material, device structure, and fabrication process. In the H 2 sensors, high semiconducting purity solution-derived CNT film sorted by poly[9-(1-octylonoyl)-9 H-carbazole-2,7-diyl](PCz) is used as the main channel, which is decorated with Pd nanoparticles as functionalization for capturing H 2 . Meanwhile, Ti contacts are used to form a Schottky barrier for enhancing transferred charge-induced resistance change, and then a response of resistance change by 3 orders of magnitude is achieved at room temperature under the concentration of ∼311 ppm with a very fast response time of approximately 7 s and a detection limit of 890 ppb, which is the highest response to date for CNT H 2 sensors and the very first time to show the sub-ppm detection for H 2 at room temperature. Furthermore, the detection limit concentration can be improved to 89 ppb at 100 °C. The batch fabrication of CNT film H 2 sensors with ultra-high sensitivity and high uniformity is ready to promote CNT devices to application for the first time in some specialized field.

Power- and Low-Resistance-State-Dependent, Bipolar Reset-Switching Transitions in SiN-Based Resistive Random-Access Memory

NASA Astrophysics Data System (ADS)

Kim, Sungjun; Park, Byung-Gook

2016-08-01

A study on the bipolar-resistive switching of an Ni/SiN/Si-based resistive random-access memory (RRAM) device shows that the influences of the reset power and the resistance value of the low-resistance state (LRS) on the reset-switching transitions are strong. For a low LRS with a large conducting path, the sharp reset switching, which requires a high reset power (>7 mW), was observed, whereas for a high LRS with small multiple-conducting paths, the step-by-step reset switching with a low reset power (<7 mW) was observed. The attainment of higher nonlinear current-voltage ( I-V) characteristics in terms of the step-by-step reset switching is due to the steep current-increased region of the trap-controlled space charge-limited current (SCLC) model. A multilevel cell (MLC) operation, for which the reset stop voltage ( V STOP) is used in the DC sweep mode and an incremental amplitude is used in the pulse mode for the step-by-step reset switching, is demonstrated here. The results of the present study suggest that well-controlled conducting paths in a SiN-based RRAM device, which are not too strong and not too weak, offer considerable potential for the realization of low-power and high-density crossbar-array applications.

Fabrication techniques for superconducting readout loops

NASA Technical Reports Server (NTRS)

Payne, J. E.

1982-01-01

Procedures for the fabrication of superconducting readout loops out of niobium on glass substrates were developed. A computer program for an existing fabrication system was developed. Both positive and negative resist procedures for the production of the readout loops were investigated. Methods used to produce satisfactory loops are described and the various parameters affecting the performance of the loops are analyzed.

A simple fabrication of CH3NH3PbI3 perovskite for solar cells using low-purity PbI2

NASA Astrophysics Data System (ADS)

Guo, Nanjie; Zhang, Taiyang; Li, Ge; Xu, Feng; Qian, Xufang; Zhao, Yixin

2017-01-01

The CH3NH3PbI3 (MAPbI3) perovskite was usually prepared by high-purity PbI2 with high cost. The low cost and low-purity PbI2 was seldom reported for fabrication of MAPbI3 because it cannot even dissolve well in widely adopted solvent of DMF. We developed an easy method to adapt low-purity PbI2 for fabrication of high quality MAPbI3 just by the simple addition of some hydrochloric acid into the mixture of low-purity PbI2, MAI and DMF. This straightforward method can not only help dissolve the low quality PbI2 by reacting with some impurities in DMF, but also lead to a successful fabrication of high-quality perovskite solar cells with up to 14.80% efficiency comparable to the high quality PbI2 precursors. Project supported by the National Natural Science Foundation of China (Nos. 51372151, 21303103) and Houyingdong Grant (No. 151046).

Sensing of low concentration of ammonia at room temperature by decorated multi-walled carbon nanotube: fabrication and characteristics

NASA Astrophysics Data System (ADS)

Hasnahena, S. T.; Roy, M.

2018-01-01

A chemical sensor based on multi-walled carbon nanotube (MWCNT) decorated with densely populated thiol-capped gold nanoparticles (AuNPs) with sizes smaller than 3 nm for sensing low concentrations of ammonia gas is reported. The functionalized MWCNTs, subsequently decorated with AuNPs following an easy fabrication route were exposed to NH3 gas at the room temperature and the electrical resistance of the sensor changed upon exposure. The sensor also partially recovered the initial state after sensing in the normal air environment (without any dry air or N2 gas purge). The gold nanoparticles decoration is found to enhance the sensitivity and selectivity of MWCNT towards NH3 gas under ambient conditions with a reduced response and recovery time. The material was structurally characterized by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. Thermal stability of the sensor till 574 °C was demonstrated by TGA analysis. This papers describes how thiol-capped AuNPs are uniformly decorated on the outer walls of the MWCNTs with a separation of 2-3 nm making use of the ionic nature of Au and how this uniform distribution of AuNPs increases the active sites for absorption of NH3 gas molecules leading to sensing its low concentrations.

Investigation of resistive switching behaviours in WO3-based RRAM devices

NASA Astrophysics Data System (ADS)

Li, Ying-Tao; Long, Shi-Bing; Lü, Hang-Bing; Liu, Qi; Wang, Qin; Wang, Yan; Zhang, Sen; Lian, Wen-Tai; Liu, Su; Liu, Ming

2011-01-01

In this paper, a WO3-based resistive random access memory device composed of a thin film of WO3 sandwiched between a copper top and a platinum bottom electrodes is fabricated by electron beam evaporation at room temperature. The reproducible resistive switching, low power consumption, multilevel storage possibility, and good data retention characteristics demonstrate that the Cu/WO3/Pt memory device is very promising for future nonvolatile memory applications. The formation and rupture of localised conductive filaments is suggested to be responsible for the observed resistive switching behaviours.