Science.gov

Sample records for 50-100 nm diameter

  1. Fabrication of 10nm diameter carbon nanopores

    SciTech Connect

    Radenovic, Aleksandra; Trepagnier, Eliane; Csencsits, Roseann; Downing, Kenneth H; Liphardt, Jan

    2008-09-25

    The addition of carbon to samples, during imaging, presents a barrier to accurate TEM analysis, the controlled deposition of hydrocarbons by a focused electron beam can be a useful technique for local nanometer-scale sculpting of material. Here we use hydrocarbon deposition to form nanopores from larger focused ion beam (FIB) holes in silicon nitride membranes. Using this method, we close 100-200nm diameter holes to diameters of 10nm and below, with deposition rates of 0.6nm per minute. I-V characteristics of electrolytic flow through these nanopores agree quantitatively with a one dimensional model at all examined salt concentrations.

  2. Magnetic configurations in 160 520-nm-diameter ferromagnetic rings

    NASA Astrophysics Data System (ADS)

    Castaño, F. J.; Ross, C. A.; Eilez, A.; Jung, W.; Frandsen, C.

    2004-04-01

    The remanent states and hysteretic behavior of thin-film magnetic rings has been investigated experimentally and by micromagnetic modeling. Rings of diameters 160 520 nm, made from Co using lift-off processing, show three distinct remanent states: a vortex state, an “onion” state with two head-on walls, and a “twisted” state containing a 360° wall. The range of stability of these states varies with ring geometry, with smaller width rings showing higher switching fields and greater variability.

  3. Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

    PubMed Central

    Kiomarsi, Nazanin; Salim, Soheil; Sarraf, Pegah; Javad-Kharazifard, Mohammad

    2016-01-01

    Background The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching. Material and Methods The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05). Results A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching. Conclusions The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material. Key words:Laser, diode, dentin, tubule, diameter. PMID:27398172

  4. Precise Fabrication of Nanopores with Diameters of Sub-1 nm to 3 nm Using Multilevel Pulse-voltage Injection

    NASA Astrophysics Data System (ADS)

    Yanagi, Itaru; Akahori, Rena; Yokoi, Takahide; Takeda, Ken-Ichi

    2015-03-01

    To date, solid-state nanopores have been fabricated primarily through a focused-electronic beam via TEM. For mass production, however, a TEM beam is not suitable and an alternative fabrication method is required. Recently, a simple nanopore-fabrication method has been reported that is based on a dielectric breakdown phenomenon of a thin membrane. In this study, to stably fabricate nanopores with diameters of 1 to 2 nm (which is an essential size for distinguishing each nucleotide) via dielectric breakdown, a technique called multilevel pulse-voltage injection (MPVI) is proposed and demonstrated. MPVI uses pulse voltages for generating the nanopores, and the generation of the nanopores is verified by measuring the current through a membrane at low voltage. This method can generate nanopores with diameters of less than 1 nm in a 10-nm-thick Si3N4 membrane with a probability of 90%. The diameter of the generated nanopores can be widened to the desired diameters (up to 3 nm) with sub-nanometre precision. The mean effective thickness of the fabricated nanopores was 3.7 nm. These findings are derived from TEM images of the fabricated nanopores and analyses of ionic-current blockades during single-stranded DNA translocation.

  5. Fabricating nanopores with diameters of sub-1 nm to 3 nm using multilevel pulse-voltage injection

    PubMed Central

    Yanagi, Itaru; Akahori, Rena; Hatano, Toshiyuki; Takeda, Ken-ichi

    2014-01-01

    To date, solid-state nanopores have been fabricated primarily through a focused-electronic beam via TEM. For mass production, however, a TEM beam is not suitable and an alternative fabrication method is required. Recently, a simple method for fabricating solid-state nanopores was reported by Kwok, H. et al. and used to fabricate a nanopore (down to 2 nm in size) in a membrane via dielectric breakdown. In the present study, to fabricate smaller nanopores stably—specifically with a diameter of 1 to 2 nm (which is an essential size for identifying each nucleotide)—via dielectric breakdown, a technique called “multilevel pulse-voltage injection” (MPVI) is proposed and evaluated. MPVI can generate nanopores with diameters of sub-1 nm in a 10-nm-thick Si3N4 membrane with a probability of 90%. The generated nanopores can be widened to the desired size (as high as 3 nm in diameter) with sub-nanometre precision, and the mean effective thickness of the fabricated nanopores was 3.7 nm. PMID:24847795

  6. Synthesis of monodisperse mesoporous titania beads with controllable diameter, high surface areas, and variable pore diameters (14-23 nm).

    PubMed

    Chen, Dehong; Cao, Lu; Huang, Fuzhi; Imperia, Paolo; Cheng, Yi-Bing; Caruso, Rachel A

    2010-03-31

    Monodisperse mesoporous anatase titania beads with high surface areas and tunable pore size and grain diameter have been prepared through a combined sol-gel and solvothermal process in the presence of hexadecylamine (HDA) as a structure-directing agent. The monodispersity of the resultant titania beads, along with the spherical shape, can be controlled by varying the amount of structure-directing agent involved in the sol-gel process. The diameter of the titania beads is tunable from approximately 320 to 1150 nm by altering the hydrolysis and condensation rates of the titanium alkoxide. The crystallite size, specific surface area (from 89 to 120 m(2)/g), and pore size distribution (from 14 to 23 nm) of the resultant materials can be varied through a mild solvothermal treatment in the presence of varied amounts of ammonia. On the basis of the results of small-angle XRD, high-resolution SEM/TEM, and gas sorption characterization, a mechanism for the formation of the monodisperse precursor beads has been proposed to illustrate the role of HDA in determining the morphology and monodispersity during the sol-gel synthesis. The approach presented in this study demonstrates that simultaneous control of the physical properties, including specific surface area, mesoporosity, crystallinity, morphology, and monodispersity, of the titania materials can be achieved by a facile sol-gel synthesis and solvothermal process. PMID:20201515

  7. Gold Nanoparticles of Diameter 13 nm Induce Apoptosis in Rabbit Articular Chondrocytes

    NASA Astrophysics Data System (ADS)

    Huang, Hao; Quan, Ying-yao; Wang, Xiao-ping; Chen, Tong-sheng

    2016-05-01

    Gold nanoparticles (AuNPs) have been widely used in biomedical science including antiarthritic agents, drug loading, and photothermal therapy. In this report, we studied the effects of AuNPs with diameters of 3, 13, and 45 nm, respectively, on rabbit articular chondrocytes. AuNPs were capped with citrate and their diameter and zeta potential were measured by dynamic light scattering (DLS). Cell viability was evaluated by Cell Counting Kit-8 (CCK-8) assay after the rabbit articular chondrocytes were pre-incubated with 3, 13, and 45 nm AuNPs, respectively, for 24 h. Flow cytometry (FCM) analysis with annexin V/propidium iodide (PI) double staining and fluorescence imaging with Hoechst 33258 staining were used to determine the fashion of AuNPs-induced chondrocyte death. Further, 13 nm AuNPs (2 nM) significantly induced chondrocyte death accompanying apoptotic characteristics including mitochondrial damage, externalization of phosphatidylserine and nuclear concentration. However, 3 nm AuNPs (2 nM) and 45 nm (0.02 nM) AuNPs did not induce cytotoxicity in chondrocytes. Although 13 nm AuNPs (2 nM) increased the intracellular reactive oxygen species (ROS) level, pretreatment with Nacetyl cysteine (NAC), a ROS scavenger, did not prevent the cytotoxicity induced by 13 nm AuNPs, indicating that 13 nm AuNPs (2 nM) induced ROS-independent apoptosis in chondrocytes. These results demonstrate the size-dependent cytotoxicity of AuNPs in chondrocytes, which must be seriously considered when using AuNPs for treatment of osteoarthritis (OA).

  8. Gold Nanoparticles of Diameter 13 nm Induce Apoptosis in Rabbit Articular Chondrocytes.

    PubMed

    Huang, Hao; Quan, Ying-Yao; Wang, Xiao-Ping; Chen, Tong-Sheng

    2016-12-01

    Gold nanoparticles (AuNPs) have been widely used in biomedical science including antiarthritic agents, drug loading, and photothermal therapy. In this report, we studied the effects of AuNPs with diameters of 3, 13, and 45 nm, respectively, on rabbit articular chondrocytes. AuNPs were capped with citrate and their diameter and zeta potential were measured by dynamic light scattering (DLS). Cell viability was evaluated by Cell Counting Kit-8 (CCK-8) assay after the rabbit articular chondrocytes were pre-incubated with 3, 13, and 45 nm AuNPs, respectively, for 24 h. Flow cytometry (FCM) analysis with annexin V/propidium iodide (PI) double staining and fluorescence imaging with Hoechst 33258 staining were used to determine the fashion of AuNPs-induced chondrocyte death. Further, 13 nm AuNPs (2 nM) significantly induced chondrocyte death accompanying apoptotic characteristics including mitochondrial damage, externalization of phosphatidylserine and nuclear concentration. However, 3 nm AuNPs (2 nM) and 45 nm (0.02 nM) AuNPs did not induce cytotoxicity in chondrocytes. Although 13 nm AuNPs (2 nM) increased the intracellular reactive oxygen species (ROS) level, pretreatment with Nacetyl cysteine (NAC), a ROS scavenger, did not prevent the cytotoxicity induced by 13 nm AuNPs, indicating that 13 nm AuNPs (2 nM) induced ROS-independent apoptosis in chondrocytes. These results demonstrate the size-dependent cytotoxicity of AuNPs in chondrocytes, which must be seriously considered when using AuNPs for treatment of osteoarthritis (OA). PMID:27178054

  9. Anodized 20 nm diameter nanotubular titanium for improved bladder stent applications

    PubMed Central

    Alpaslan, Ece; Ercan, Batur; Webster, Thomas J

    2011-01-01

    Materials currently used for bladder applications often suffer from incomplete coverage by urothelial cells (cells that line the interior of the bladder and ureter) which leads to the continuous exposure of the underlying materials aggravating an immune response. In particular, a ureteral (or sometimes called an ureteric or bladder) stent is a thin tube inserted into the ureter to prevent or treat obstruction of urine flow from the kidney. The main complications with ureteral stents are infection and blockage by encrustation, which can be avoided by promoting the formation of a monolayer of urothelial cells on the surface of the stent. Nanotechnology (or the use of nanomaterials) may aid in urothelialization of bladder stents since nanomaterials have been shown to have unique surface energetics to promote the adsorption of proteins important for urothelial cell adhesion and proliferation. Since many bladder stents are composed of titanium, this study investigated the attachment and spreading of human urothelial cells on different nanotextured titanium surfaces. An inexpensive and effective scaled up anodization process was used to create equally distributed nanotubular surfaces of different diameter sizes from 20–80 nm on titanium with lengths approximately 500 nm. Results showed that compared to untreated titanium stents and 80 nm diameter nanotubular titanium, 20 nm diameter nanotubular titanium stents enhanced human urothelial cell adhesion and growth up to 3 days in culture. In this manner, this study suggests that titanium anodized to possess nanotubular surface features should be further explored for bladder stent applications. PMID:21499419

  10. Translocation of 40 nm diameter nanowires through the intestinal epithelium of Daphnia magna

    PubMed Central

    Mattsson, Karin; Adolfsson, Karl; Ekvall, Mikael T.; Borgström, Magnus T.; Linse, Sara; Hansson, Lars-Anders; Cedervall, Tommy; Prinz, Christelle N.

    2016-01-01

    Abstract Nanowires (NWs) have unique electrical and optical properties of value for many applications including lighting, sensing, and energy harnessing. Consumer products containing NWs increase the risk of NWs being released in the environment, especially into aquatic ecosystems through sewage systems. Daphnia magna is a common, cosmopolitan freshwater organism sensitive to toxicity tests and represents a likely entry point for nanoparticles into food webs of aquatic ecosystems. Here we have evaluated the effect of NW diameter on the gut penetrance of NWs in Daphnia magna. The animals were exposed to NWs of two diameters (40 and 80 nm) and similar length (3.6 and 3.8 μm, respectively) suspended in water. In order to locate the NWs in Daphnia, the NWs were designed to comprise one inherently fluorescent segment of gallium indium phosphide (GaInP) flanked by a gallium phosphide (GaP) segment. Daphnia mortality was assessed directly after 24 h of exposure and 7 days after exposure. Translocation of NWs across the intestinal epithelium was investigated using confocal fluorescence microscopy directly after 24 h of exposure and was observed in 89% of Daphnia exposed to 40 nm NWs and in 11% of Daphnia exposed to 80 nm NWs. A high degree of fragmentation was observed for NWs of both diameters after ingestion by the Daphnia, although 40 nm NWs were fragmented to a greater extent, which could possibly facilitate translocation across the intestinal epithelium. Our results show that the feeding behavior of animals may enhance the ability of NWs to penetrate biological barriers and that penetrance is governed by the NW diameter. PMID:27181920

  11. Translocation of 40 nm diameter nanowires through the intestinal epithelium of Daphnia magna.

    PubMed

    Mattsson, Karin; Adolfsson, Karl; Ekvall, Mikael T; Borgström, Magnus T; Linse, Sara; Hansson, Lars-Anders; Cedervall, Tommy; Prinz, Christelle N

    2016-10-01

    Nanowires (NWs) have unique electrical and optical properties of value for many applications including lighting, sensing, and energy harnessing. Consumer products containing NWs increase the risk of NWs being released in the environment, especially into aquatic ecosystems through sewage systems. Daphnia magna is a common, cosmopolitan freshwater organism sensitive to toxicity tests and represents a likely entry point for nanoparticles into food webs of aquatic ecosystems. Here we have evaluated the effect of NW diameter on the gut penetrance of NWs in Daphnia magna. The animals were exposed to NWs of two diameters (40 and 80 nm) and similar length (3.6 and 3.8 μm, respectively) suspended in water. In order to locate the NWs in Daphnia, the NWs were designed to comprise one inherently fluorescent segment of gallium indium phosphide (GaInP) flanked by a gallium phosphide (GaP) segment. Daphnia mortality was assessed directly after 24 h of exposure and 7 days after exposure. Translocation of NWs across the intestinal epithelium was investigated using confocal fluorescence microscopy directly after 24 h of exposure and was observed in 89% of Daphnia exposed to 40 nm NWs and in 11% of Daphnia exposed to 80 nm NWs. A high degree of fragmentation was observed for NWs of both diameters after ingestion by the Daphnia, although 40 nm NWs were fragmented to a greater extent, which could possibly facilitate translocation across the intestinal epithelium. Our results show that the feeding behavior of animals may enhance the ability of NWs to penetrate biological barriers and that penetrance is governed by the NW diameter. PMID:27181920

  12. Synthesis and bioconjugation of 2 and 3 nm-diameter gold nanoparticles.

    PubMed

    Ackerson, Christopher J; Jadzinsky, Pablo D; Sexton, Jonathan Z; Bushnell, David A; Kornberg, Roger D

    2010-02-17

    By adjustment of solvent conditions for synthesis, virtually monodisperse 4-mercaptobenzoic acid (p-MBA) monolayer-protected gold nanoparticles, 2 and 3 nm in diameter, were obtained. Large single crystals of the 2 nm particles could be grown from the reaction mixture. Uniformity was also demonstrated by the formation of two-dimensional arrays and by quantitative high-angle annular dark-field scanning transmission electron microscopy. The 2 and 3 nm particles were spontaneously reactive for conjugation with proteins and DNA, and further reaction could be prevented by repassivation with glutathione. Conjugates with antibody Fc fragment could be used to identify TAP-tagged proteins of interest in electron micrographs, through the binding of a pair of particles to the pair of protein A domains in the TAP tag. PMID:20099843

  13. Ultrafast proton transport in sub-1-nm diameter carbon nanotube porins.

    PubMed

    Tunuguntla, Ramya H; Allen, Frances I; Kim, Kyunghoon; Belliveau, Allison; Noy, Aleksandr

    2016-07-01

    Proton transport plays an important role in many biological processes due to the ability of protons to rapidly translocate along chains of hydrogen-bonded water molecules. Molecular dynamics simulations have predicted that confinement in hydrophobic nanochannels should enhance the rate of proton transport. Here, we show that 0.8-nm-diameter carbon nanotube porins, which promote the formation of one-dimensional water wires, can support proton transport rates exceeding those of bulk water by an order of magnitude. The transport rates in these narrow nanotube pores also exceed those of biological channels and Nafion. With larger 1.5-nm-diameter nanotube porins, proton transport rates comparable to bulk water are observed. We also show that the proton conductance of these channels can be modulated by the presence of Ca(2+) ions. Our results illustrate the potential of small-diameter carbon nanotube porins as a proton conductor material and suggest that strong spatial confinement is a key factor in enabling efficient proton transport. PMID:27043198

  14. Ultrafast proton transport in sub-1-nm diameter carbon nanotube porins

    NASA Astrophysics Data System (ADS)

    Tunuguntla, Ramya H.; Allen, Frances I.; Kim, Kyunghoon; Belliveau, Allison; Noy, Aleksandr

    2016-07-01

    Proton transport plays an important role in many biological processes due to the ability of protons to rapidly translocate along chains of hydrogen-bonded water molecules. Molecular dynamics simulations have predicted that confinement in hydrophobic nanochannels should enhance the rate of proton transport. Here, we show that 0.8-nm-diameter carbon nanotube porins, which promote the formation of one-dimensional water wires, can support proton transport rates exceeding those of bulk water by an order of magnitude. The transport rates in these narrow nanotube pores also exceed those of biological channels and Nafion. With larger 1.5-nm-diameter nanotube porins, proton transport rates comparable to bulk water are observed. We also show that the proton conductance of these channels can be modulated by the presence of Ca2+ ions. Our results illustrate the potential of small-diameter carbon nanotube porins as a proton conductor material and suggest that strong spatial confinement is a key factor in enabling efficient proton transport.

  15. Observation of sea-salt fraction in sub-100 nm diameter particles at Cape Grim

    NASA Astrophysics Data System (ADS)

    Cravigan, Luke T.; Ristovski, Zoran; Modini, Robin L.; Keywood, Melita D.; Gras, John L.

    2015-03-01

    Volatility-hygroscopicity tandem differential mobility analyzer measurements were used to infer the composition of sub-100 nm diameter Southern Ocean marine aerosols at Cape Grim in November and December 2007. This study focuses on a short-lived high sea spray aerosol (SSA) event on 7-8 December with two externally mixed modes in the Hygroscopic Growth Factor (HGF) distributions (90% relative humidity (RH)), one at HGF > 2 and another at HGF~1.5. The particles with HGF > 2 displayed a deliquescent transition at 73-75% RH and were nonvolatile up to 280°C, which identified them as SSA particles with a large inorganic sea-salt fraction. SSA HGFs were 3-13% below those for pure sea-salt particles, indicating an organic volume fraction (OVF) of up to 11-46%. Observed high inorganic fractions in sub-100 nm SSA is contrary to similar, earlier studies. HGFs increased with decreasing particle diameter over the range 16-97 nm, suggesting a decreased OVF, again contrary to earlier studies. SSA comprised up to 69% of the sub-100 nm particle number, corresponding to concentrations of 110-290 cm-3. Air mass back trajectories indicate that SSA particles were produced 1500 km, 20-40 h upwind of Cape Grim. Transmission electron microscopy (TEM) and X-ray spectrometry measurements of sub-100 nm aerosols collected from the same location, and at the same time, displayed a distinct lack of sea salt. Results herein highlight the potential for biases in TEM analysis of the chemical composition of marine aerosols.

  16. Super stretchable hydrogel achieved by non-aggregated spherulites with diameters <5 nm

    PubMed Central

    Sun, Guoxing; Li, Zongjin; Liang, Rui; Weng, Lu-Tao; Zhang, Lina

    2016-01-01

    The scope of hydrogel applications can be greatly expanded by the improvement of mechanical properties. However, enhancement of nanocomposite hydrogels (NC gels) has been severely limited because the size of crosslinking nanoparticles is too large, at least in one dimension. Here we report a new strategy to synthesize non-aggregated spherulite nanoparticles, with diameters <5 nm, in aqueous solution, and their enhancement to hydrogel. The stress and stretch ratio at rupture of our NC gel are 430 and 121 KPa with only 40-p.p.m. nanoparticle content. The NC gel containing 200-p.p.m. nanoparticles can revert to 90% of its original size after enduring 100-MPa compressive stress. Our results demonstrate that the suppression of nanoparticle size without aggregation helps to establish a super stretchable and high-toughness hydrogel network at very low inorganic content. PMID:27352822

  17. Super stretchable hydrogel achieved by non-aggregated spherulites with diameters <5 nm.

    PubMed

    Sun, Guoxing; Li, Zongjin; Liang, Rui; Weng, Lu-Tao; Zhang, Lina

    2016-01-01

    The scope of hydrogel applications can be greatly expanded by the improvement of mechanical properties. However, enhancement of nanocomposite hydrogels (NC gels) has been severely limited because the size of crosslinking nanoparticles is too large, at least in one dimension. Here we report a new strategy to synthesize non-aggregated spherulite nanoparticles, with diameters <5 nm, in aqueous solution, and their enhancement to hydrogel. The stress and stretch ratio at rupture of our NC gel are 430 and 121 KPa with only 40-p.p.m. nanoparticle content. The NC gel containing 200-p.p.m. nanoparticles can revert to 90% of its original size after enduring 100-MPa compressive stress. Our results demonstrate that the suppression of nanoparticle size without aggregation helps to establish a super stretchable and high-toughness hydrogel network at very low inorganic content. PMID:27352822

  18. Empirical relationships between optical properties and equivalent diameters of fractal soot aggregates at 550 nm wavelength.

    PubMed

    Pandey, Apoorva; Chakrabarty, Rajan K; Liu, Li; Mishchenko, Michael I

    2015-11-30

    Soot aggregates (SAs)-fractal clusters of small, spherical carbonaceous monomers-modulate the incoming visible solar radiation and contribute significantly to climate forcing. Experimentalists and climate modelers typically assume a spherical morphology for SAs when computing their optical properties, causing significant errors. Here, we calculate the optical properties of freshly-generated (fractal dimension Df = 1.8) and aged (Df = 2.6) SAs at 550 nm wavelength using the numerically-exact superposition T-Matrix method. These properties were expressed as functions of equivalent aerosol diameters as measured by contemporary aerosol instruments. This work improves upon previous efforts wherein SA optical properties were computed as a function of monomer number, rendering them unusable in practical applications. Future research will address the sensitivity of variation in refractive index, fractal prefactor, and monomer overlap of SAs on the reported empirical relationships. PMID:26698786

  19. Empirical Relationships Between Optical Properties and Equivalent Diameters of Fractal Soot Aggregates at 550 Nm Wavelength.

    NASA Technical Reports Server (NTRS)

    Pandey, Apoorva; Chakrabarty, Rajan K.; Liu, Li; Mishchenko, Michael I.

    2015-01-01

    Soot aggregates (SAs)-fractal clusters of small, spherical carbonaceous monomers-modulate the incoming visible solar radiation and contribute significantly to climate forcing. Experimentalists and climate modelers typically assume a spherical morphology for SAs when computing their optical properties, causing significant errors. Here, we calculate the optical properties of freshly-generated (fractal dimension Df = 1.8) and aged (Df = 2.6) SAs at 550 nm wavelength using the numericallyexact superposition T-Matrix method. These properties were expressed as functions of equivalent aerosol diameters as measured by contemporary aerosol instruments. This work improves upon previous efforts wherein SA optical properties were computed as a function of monomer number, rendering them unusable in practical applications. Future research will address the sensitivity of variation in refractive index, fractal prefactor, and monomer overlap of SAs on the reported empirical relationships.

  20. Direct Probes of 4 nm Diameter Gold Nanoparticles Interacting with Supported Lipid Bylayers

    SciTech Connect

    Troiano, Julianne; Olenick, Laura L.; Kuech, Thomas R.; Melby, Eric S.; Hu, Dehong; Lohse, Samuel E.; Mensch, Arielle C.; Dogangun, Merve; Vartanian, Arlane M.; Torelli, Marco; Ehimiaghe, Eseohi; Walter, Stephanie R.; Fu, Li; Anderton, Christopher R.; Zhu, Zihua; Wang, Hongfei; Orr, Galya; Murphy, Catherine; Hamers, Robert J.; Pedersen, Joel A.; Geiger, Franz M.

    2015-01-08

    Interfacial charge densities and potentials are determined for silica-supported phospholipid bilayers formed from lipids having zwitterionic, negatively charged, and positively charged headgroups. Quartz crystal microbalance with dissipation (QCM-D), fluorescence recovery after photobleaching (FRAP), and atomic force microscopy demonstrate the presence of well-formed supported lipid bilayers, which, as probed by vibrational sum frequency generation (SFG), undergo negligible structural changes along their alkyl chains when NaCl concentration is raised from 0.001 to 0.1 M. From second harmonic generation (SHG) measurements we estimate that each zwitterionic headgroup of the bilayer formed from pure DOPC is associated with an apparent charge of -0.028(+0.008/-0.007)×10-¹⁹C, corresponding to 1.8 ± 0.5 % of an elementary negative charge. Moreover, we show that a supported lipid bilayer carrying an apparent negative interfacial potential may interact with not just positively charged 4-nm diameter gold nanoparticles but also negatively charged gold nanoparticles. In this latter case, charge-charge repulsion does not appear to inhibit particle-bilayer interactions and is likely overcome by multivalent interactions that are estimated to involve 3-5 hydrogen-bond equivalents. FRAP, QCM-D, and SFG measurements indicate that the bilayers remain intact under the conditions of the experiments. SHG charge screening experiments are consistent with an apparent zero net charge density associated with the positively charged gold nanoparticles when they are attached to a supported lipid bilayer carrying an apparent negative potential. The results presented here serve to benchmark experimental and computational studies of the nano-bio interface.

  1. 41 CFR 128-50.100 - Storage and care.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Storage and care. 128-50.100 Section 128-50.100 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF JUSTICE 50-SEIZED PERSONAL PROPERTY 50.1-Storage and Care of Seized Personal Property § 128-50.100 Storage...

  2. 41 CFR 128-50.100 - Storage and care.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Storage and care. 128-50.100 Section 128-50.100 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF JUSTICE 50-SEIZED PERSONAL PROPERTY 50.1-Storage and Care of Seized Personal Property § 128-50.100 Storage...

  3. Micromagnetic simulations of 200-nm-diameter cobalt nanorings using a Reuleaux triangular geometry

    NASA Astrophysics Data System (ADS)

    Torres-Heredia, J. J.; López-Urías, F.; Muñoz-Sandoval, E.

    2006-10-01

    Using micromagnetic simulations, we investigated the magnetic states and switching processes of Co nanorings with lateral dimensions of 200 nm. We propose a special geometry of nanorings that adopts different Reuleaux triangular shapes. Reuleaux's triangles (RT) combine both the equilateral triangle and circular geometries. We studied the magnetic spin configurations of individual nanorings by varying the thickness and geometry of the nanomagnets. Our results demonstrated that in most nanomagnets exhibiting a thickness of less than 4 nm, there exists an onion-type state, which precedes either a twisted, double twisted, or cardioid state, when studying the magnetization reversal process. The hysteresis loops and magnetic states found in these RTs are compared with circular nanorings.

  4. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    NASA Astrophysics Data System (ADS)

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-11-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5-2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0-2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed.

  5. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    PubMed Central

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-01-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5–2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0–2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed. PMID:26527044

  6. Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulation

    PubMed Central

    Balme, Sébastien; Picaud, Fabien; Manghi, Manoel; Palmeri, John; Bechelany, Mikhael; Cabello-Aguilar, Simon; Abou-Chaaya, Adib; Miele, Philippe; Balanzat, Emmanuel; Janot, Jean Marc

    2015-01-01

    Fundamental understanding of ionic transport at the nanoscale is essential for developing biosensors based on nanopore technology and new generation high-performance nanofiltration membranes for separation and purification applications. We study here ionic transport through single putatively neutral hydrophobic nanopores with high aspect ratio (of length L = 6 μm with diameters ranging from 1 to 10 nm) and with a well controlled cylindrical geometry. We develop a detailed hybrid mesoscopic theoretical approach for the electrolyte conductivity inside nanopores, which considers explicitly ion advection by electro-osmotic flow and possible flow slip at the pore surface. By fitting the experimental conductance data we show that for nanopore diameters greater than 4 nm a constant weak surface charge density of about 10−2 C m−2 needs to be incorporated in the model to account for conductance plateaus of a few pico-siemens at low salt concentrations. For tighter nanopores, our analysis leads to a higher surface charge density, which can be attributed to a modification of ion solvation structure close to the pore surface, as observed in the molecular dynamics simulations we performed. PMID:26036687

  7. Growth and Physical Property Study of Single Nanowire (Diameter ~45 nm) of Half Doped Manganite

    DOE PAGESBeta

    Datta, Subarna; Chandra, Sayan; Samanta, Sudeshna; Das, K.; Srikanth, H.; Ghosh, Barnali

    2013-01-01

    We repormore » t here the growth and characterization of functional oxide nanowire of hole doped manganite of La 0.5 Sr 0.5 MnO 3 (LSMO). We also report four-probe electrical resistance measurement of a single nanowire of LSMO (diameter ~45 nm) using focused ion beam (FIB) fabricated electrodes. The wires are fabricated by hydrothermal method using autoclave at a temperature of 270 °C. The elemental analysis and physical property like electrical resistivity are studied at an individual nanowire level. The quantitative determination of Mn valency and elemental mapping of constituent elements are done by using Electron Energy Loss Spectroscopy (EELS) in the Transmission Electron Microscopy (TEM) mode. We address the important issue of whether as a result of size reduction the nanowires can retain the desired composition, structure, and physical properties. The nanowires used are found to have a ferromagnetic transition ( T C ) at around 325 K which is very close to the bulk value of around 330 K found in single crystal of the same composition. It is confirmed that the functional behavior is likely to be retained even after size reduction of the nanowires to a diameter of 45 nm. The electrical resistivity shows insulating behavior within the measured temperature range which is similar to the bulk system.« less

  8. Preparation of PCDTBT nanofibers with a diameter of 20 nm and their application to air-processed organic solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Taehoon; Yang, Seung Jae; Kim, Sung Kyun; Choi, Hong Soo; Park, Chong Rae

    2014-02-01

    A strategy for fabricating organic photovoltaic (OPV) devices based on PCDTBT nanofibers and PC70BM is described. Electrospinning techniques are used to prepare PCDTBT nanofibers and OPV devices in ambient air. The diameters of the PCDTBT nanofibers are approximately twice the exciton diffusion length, 20 nm. The active layer exhibits 100% photoluminescence quenching due to the small nanofiber diameter, indicating that the excitons are efficiently dissociated. The electrospun PCDTBT nanofibers absorb more photons at longer wavelengths, leading to improved photon harvesting. OPV devices composed of PCDTBT nanofibers show a high short circuit current of 11.54 mA cm-2 and a high power conversion efficiency of 5.82%. The increase in the short circuit current is attributed to enhanced photon harvesting and charge transport. This method may be applied to the fabrication, in ambient air, of large-area active layers composed of other new conjugated polymers to yield high-performance OPV devices.A strategy for fabricating organic photovoltaic (OPV) devices based on PCDTBT nanofibers and PC70BM is described. Electrospinning techniques are used to prepare PCDTBT nanofibers and OPV devices in ambient air. The diameters of the PCDTBT nanofibers are approximately twice the exciton diffusion length, 20 nm. The active layer exhibits 100% photoluminescence quenching due to the small nanofiber diameter, indicating that the excitons are efficiently dissociated. The electrospun PCDTBT nanofibers absorb more photons at longer wavelengths, leading to improved photon harvesting. OPV devices composed of PCDTBT nanofibers show a high short circuit current of 11.54 mA cm-2 and a high power conversion efficiency of 5.82%. The increase in the short circuit current is attributed to enhanced photon harvesting and charge transport. This method may be applied to the fabrication, in ambient air, of large-area active layers composed of other new conjugated polymers to yield high-performance OPV

  9. Quantum size effect on Shubnikov-de Haas oscillations in 100 nm diameter single-crystalline bismuth nanowire

    NASA Astrophysics Data System (ADS)

    Kim, Jeongmin; Kim, Dohun; Chang, Taehoo; Lee, Wooyoung

    2014-09-01

    Quantum size effect (QSE) in Bi nanowire is theoretically predicted to decrease band overlap energy resulting in semimetal-to-semiconductor transition. However, this effect has been rarely demonstrated on transport properties because of carrier-surface scattering and charge carriers induced from surface states of Bi. We report QSE on Shubnikov-de Haas (SdH) oscillations in a single-crystalline Bi nanowire with a diameter of 100 nm. The variation of intrinsic properties estimated using SdH oscillations indicates that the subband energy shift due to QSE. The enhanced effective mass of the electrons is consistent with the theoretical prediction pertaining to strong electron-hole coupling of Bi.

  10. CMOS SPADs with up to 500 μm diameter and 55% detection efficiency at 420 nm

    NASA Astrophysics Data System (ADS)

    Villa, Federica; Bronzi, Danilo; Zou, Yu; Scarcella, Carmelo; Boso, Gianluca; Tisa, Simone; Tosi, Alberto; Zappa, Franco; Durini, Daniel; Weyers, Sascha; Paschen, Uwe; Brockherde, Werner

    2014-01-01

    Many demanding applications require single-photon detectors with very large active area, very low noise, high detection efficiency, and precise time response. Single-photon avalanche diodes (SPADs) provide all the advantages of solid-state devices, but in many applications other single-photon detectors, like photomultiplier tubes, have been preferred so far due to their larger active area. We developed silicon SPADs with active area diameters as large as 500 μm in a fully standard CMOS process. The 500 μm SPAD exhibits 55% peak photon detection efficiency at 420 nm, 8 kcps of dark counting rate at 0°C, and high uniformity of the sensitivity in the active area. These devices can be used with on-chip integrated quenching circuitry, which reduces the afterpulsing probability, or with external circuits to achieve even better photon-timing performances, as good as 92 ps FWHM for a 100 μm diameter SPAD. Owing to the state-of-the-art performance, not only compared to CMOS SPADs but also SPADs developed in custom technologies, very high uniformity and low crosstalk probability, these CMOS SPADs can be successfully employed in detector arrays and single-chip imagers for single-photon counting and timing applications.

  11. Diameter control of single-walled carbon nanotube forests from 1.3–3.0 nm by arc plasma deposition

    PubMed Central

    Chen, Guohai; Seki, Yasuaki; Kimura, Hiroe; Sakurai, Shunsuke; Yumura, Motoo; Hata, Kenji; Futaba, Don N.

    2014-01-01

    We present a method to both precisely and continuously control the average diameter of single-walled carbon nanotubes in a forest ranging from 1.3 to 3.0 nm with ~1 Å resolution. The diameter control of the forest was achieved through tuning of the catalyst state (size, density, and composition) using arc plasma deposition of nanoparticles. This 1.7 nm control range and 1 Å precision exceed the highest reports to date. PMID:24448201

  12. Self-propelled Janus mesoporous silica nanomotors with sub-100 nm diameters for drug encapsulation and delivery.

    PubMed

    Xuan, Mingjun; Shao, Jingxin; Lin, Xiankun; Dai, Luru; He, Qiang

    2014-08-01

    The synthesis of an innovative self-propelled Janus nanomotor with a diameter of about 75 nm that can be used as a drug carrier is described. The Janus nanomotor is based on mesoporous silica nanoparticles (MSNs) with chromium/platinum metallic caps and propelled by decomposing hydrogen peroxide to generate oxygen as a driving force with speeds up to 20.2 μm s(-1) (about 267 body lengths per second). The diffusion coefficient (D) of nanomotors with different H2 O2 concentrations is calculated by tracking the movement of individual particles recorded by means of a self-assembled fluorescence microscope and is significantly larger than free Brownian motion. The traction of a single Janus MSN nanomotor is estimated to be about 13.47×10(-15) N. Finally, intracellular localization and drug release in vitro shows that the amount of Janus MSN nanomotors entering the cells is more than MSNs with same culture time and particle concentrations, meanwhile anticancer drug doxorubicin hydrochloride loaded in Janus MSNs can be slowly released by biodegradation of lipid bilayers in cells. PMID:24740913

  13. Chylomicrons produced by Caco‐2 cells contained ApoB‐48 with diameter of 80–200 nm

    PubMed Central

    Nauli, Andromeda M.; Sun, Yuxi; Whittimore, Judy D.; Atyia, Seif; Krishnaswamy, Guha; Nauli, Surya M.

    2014-01-01

    Abstract The small intestine generally transports dietary fats to circulation in triglyceride (TG)‐rich lipoproteins. The two main intestinal lipoproteins are chylomicron (CM) and very low‐density lipoprotein (VLDL). Unfortunately, studies on the CM biogenesis and intestinal transport of dietary fats have been hampered by the lack of an adequate in vitro model. In this study, we investigated the possible factors that might increase the efficiency of CM production by Caco‐2 cells. We utilized sequential NaCl gradient ultracentrifugation to isolate the CMs that were secreted by the Caco‐2 cells. To confirm the successful isolation of the CMs, we performed Fat Red 7B staining, TG reading, apolipoprotein B (ApoB) measurement, and transmission electron microcopy (TEM) analysis. We then tested the effects of cell differentiation, oleic acid, mono‐olein, egg lecithin, incubation time, and collagen matrix on CM secretion. We found that cell differentiation, oleic acid, and lecithin were critical for CM secretion. Using the Transwell system, we further confirmed that the CMs produced by our Caco‐2 cells contained significant amount of TGs and ApoB‐48 such that they could be detected without the use of isotope labeling. In conclusion, when fully differentiated Caco‐2 were challenged with oleic acid, lecithin, and sodium taurocholate, 21% of their total number of lipoproteins were CMs with the diameter of 80–200 nm. PMID:24907293

  14. Usefulness of Mesoporous Silica as a Template for the Preparation of Bundles of Bi Nanowires with Precisely Controlled Diameter Below 10 nm.

    PubMed

    Kitahara, Masaki; Kamila, Hasbuna; Shimojima, Atsushi; Wada, Hiroaki; Mori, Takao; Terasaki, Ichiro; Kuroda, Kazuyuki

    2016-03-18

    The reduction of the diameter of Bi nanowires below 10 nm has been an important target because of the theoretical prediction with regard to significant enhancement in thermoelectric performance by size reduction. In this study, we have demonstrated the usefulness of mesoporous silica with tunable pore size as a template for the preparation of thin Bi nanowires with diameters below 10 nm. Bi was deposited within the templates through a liquid phase deposition using hexane and 1,1,3,3-tetramethyldisiloxane as a solvent and reducing agent, respectively. Bundles of thin Bi nanowires with non-crystalline frameworks were successfully obtained after the template removal. The diameter was precisely controlled between about 6 nm and 9 nm. The judicious choices of mesoporous silica and deposition conditions are critical for the successful preparation. The reliable formation of such thin Bi nanowires reported here opens up exciting new possibilities. PMID:26812048

  15. Ordering of self-assembled 5-nm-diameter poly(dimethylsiloxane) nanodots with sub-10 nm pitch using ultra-narrow electron-beam-drawn guide lines and three-dimensional control

    SciTech Connect

    Zhang, Hui; Hosaka, Sumio; Yin, You

    2014-03-03

    We demonstrate the possibility of forming long-range ordered self-assembled arrays of 5-nm-diameter nanodots with pitch of 10 × 7.5 nm{sup 2} using guide line templates and low molecular weight (MW) (4700–1200 g/mol) poly(styrene)-poly(dimethylsiloxane) (PS-PDMS) for application in ultrahigh density patterned magnetic recording media. We propose a three-dimensional control which involves control of the height of the guide lines, the thickness of the PS-PDMS films, and the gap between the guide lines in order to produce 5-nm-diameter, sub-10 nm pitched nanodots with long-range order along the guide lines. Adopting a 13-nm-thick PS-PDMS film and 14-nm-high resist guide lines, the 5-nm-diameter and 10 × 7.5 nm{sup 2}-pitched self-assembled nanodots were ordered in 4–7 dot arrays with long-range order. The experimental results demonstrate that the method is suitable for the production of patterned media with magnetic recording densities of 8.6 Tbit/in.{sup 2} using low MW PS-PDMS and slim guide lines.

  16. Single Chirality Resolution Separation of Single-Wall Carbon Nanotubes up to 1.7+ nm in Diameter using Aqueous Two-Phase Extraction

    NASA Astrophysics Data System (ADS)

    Fagan, Jeffrey

    2015-03-01

    The recent development of aqueous two-phase extraction (ATPE) as a method for separating single-wall carbon nanotubes (SWCNTs) provides a scalable method for isolating many individual species of SWCNT via solution processing. In this presentation I will demonstrate that the ability of ATPE is not limited to the separation of small diameter SWCNTs < 1nm, but enables the extraction of single metallic and semiconducting SWCNT species from plasma torch, laser ablation, electric arc and even large diameter CVD grown SWCNTs. The separation range of the technique thus extends to the isolation of individual species of nanotubes up to at least 1.7 nm in diameter, a dramatic improvement beyond previous SWCNT separation methods. Optical characterization of the refined populations, and analysis of the order of (n,m) extraction with respect to the mechanism underlying the ATPE method will be presented.

  17. Molecules at the Quantum-Classical Nanoparticle Interface: Giant Mn70 Single-Molecule Magnets of ∼4 nm Diameter.

    PubMed

    Vinslava, Alina; Tasiopoulos, Anastasios J; Wernsdorfer, Wolfgang; Abboud, Khalil A; Christou, George

    2016-04-01

    Two Mn70 torus-like molecules have been obtained from the alcoholysis in EtOH and 2-ClC2H4OH of [Mn12O12(O2CMe)16(H2O)4]·4H2O·2MeCO2H (1) in the presence of NBu(n)4MnO4 and an excess of MeCO2H. The reaction in EtOH afforded [Mn70O60(O2CMe)70(OEt)20(EtOH)16(H2O)22] (2), whereas the reaction in ClC2H4OH gave [Mn70O60(O2CMe)70(OC2H4Cl)20(ClC2H4OH)18(H2O)22] (3). The complexes are nearly isostructural, each possessing a Mn70 torus structure consisting of alternating near-linear [Mn3(μ3-O)4] and cubic [Mn4(μ3-O)2(μ3-OR)2] (R = OEt, 2; R = OC2H4Cl, 3) subunits, linked together via syn,syn-μ-bridging MeCO2(-) and μ3-bridging O(2-) groups. 2 and 3 have an overall diameter of ∼4 nm and crystallize as highly ordered supramolecular nanotubes. Alternating current (ac) magnetic susceptibility measurements, performed on microcrystalline samples in the 1.8-10 K range and a 3.5 G ac field with oscillation frequencies in the 5-1500 Hz range, revealed frequency-dependent out-of-phase signals below ∼2.4 K for both molecules indicative of the slow magnetization relaxation of single-molecule magnets (SMMs). Single-crystal, magnetization vs field studies on both complexes revealed hysteresis loops below 1.5 K, thus confirming 2 and 3 to be new SMMs. The hysteresis loops do not show the steps that are characteristic of quantum tunneling of magnetization (QTM). However, low-temperature studies revealed temperature-independent relaxation rates below ∼0.2 K for both compounds, the signature of ground state QTM. Fitting of relaxation data to the Arrhenius equation gave effective barriers for magnetization reversal (Ueff) of 23 and 18 K for 2 and 3, respectively. Because the Mn70 molecule is close to the classical limit, it was also studied using a method based on the Néel-Brown model of thermally activated magnetization reversal in a classical single-domain magnetic nanoparticle. The field and sweep-rate dependence of the coercive field was investigated and yielded the energy

  18. Dental caries in Rome, 50-100 AD.

    PubMed

    Fejerskov, O; Guldager Bilde, P; Bizzarro, M; Connelly, J N; Skovhus Thomsen, J; Nyvad, B

    2012-01-01

    Scarce information exists on the clinical features of dental caries in the Imperial Roman population and no structural data on caries lesions from this period have so far been published. We report on the findings of 86 teeth (50-100 AD) found during archaeological excavations of the temple of Castor and Pollux in the Forum Romanum. We found that nearly all teeth had large carious cavities extending into the pulp. The distribution and size of the caries lesions were similar to those found in contemporary adult populations in Africa and China living without access to dental care. Most lesions had a hypermineralized zone in the dentin at the advancing front of the carious cavities as revealed by micro-computed tomography. This biological dentin reaction combined with the morphology of the cavities might indicate that some temporary topical pain relief and intervention treatment slowed down the rate of lesion progression. This is indirectly supported by examination of cavities of similar size and depth from a contemporary population without access to dental health care. In contrast to the lesions in the Roman teeth, these lesions did not exhibit a hypermineralized dentin reaction. We investigated whether the Pb isotopic composition of enamel and/or dentin of a single tooth matched that of a sample of an ancient Forum water lead pipe. The Pb isotopic composition of the tooth did not match that of the tube, suggesting that the subjects were exposed to different Pb sources during their lifetime other than the lead tubes. PMID:22796661

  19. Dependence of gain and laser power for Cu-II 780.8-nm transition on the diameter of a segmented hollow cathode discharge

    SciTech Connect

    Szalai, L.; Donko, Z.; Rozsa, K.; Tobin, R.C.

    1995-08-01

    The dependence of laser performance and discharge characteristics on the diameter of a segmented hollow cathode discharge for the Cu-II 780.8 nm transition is presented. This transition has a special importance since its upper level is common to potential CW VUV laser transitions (150--170 nm). Laser tubes with internal diameters of 2, 3, 4, and 5 mm were investigated. Decreasing the diameter resulted in an increased gain for a given current (up to 100%/m in the 2-mm diameter, 5-cm-long tube at 1-A current). The highest output power was obtained from the large-diameter tubes (20 mW from a 5-cm-long, 5-mm-diameter tube at 2-A current, without optimizing the output coupler). This work is a part of a series of investigations aimed at the optimization of the segmented hollow cathode discharge which has already been found to be the most efficient type of discharge for cathode sputtered metal ion lasers.

  20. Size-dependent magnetic properties of 100-500 nm diameter IrMn/NiFe disks made by a two-step deposition process

    NASA Astrophysics Data System (ADS)

    Liu, F.; Ross, C. A.

    2014-11-01

    A two-step etching and deposition process is presented for making nanoscale exchange-biased NiFe/IrMn disks, and their magnetic properties are described as a function of diameter and thickness. The exchange bias in nanodots with diameters of 100-500 nm was reduced and the coercivity enhanced compared to the continuous film. Etching of the NiFe film prior to depositing the IrMn lowered the exchange bias; and the exchange bias also decreased as dot diameter decreased. The results are interpreted in terms of the relation between dot size and the antiferromagnetic domain size in the IrMn. The two-step process will be useful in introducing exchange bias at local regions of a ferromagnetic film.

  1. Mechanistic insights derived from retardation and peak broadening of particles up to 200 nm in diameter in electrophoresis in semidilute polyacrylamide solutions.

    PubMed

    Radko, S P; Chrambach, A

    1998-10-01

    Rigid spherical particles in the size range of 5-200 nm diameter were subjected to capillary zone electrophoresis (CZE) in semidilute solutions of uncross-linked polyacrylamide of M(r) 5, 7 and 18 x 10(6) (PA-5, -7 and -18, respectively) of varying concentrations up to 1.6% and at field strengths varying from 68 to 270 V/cm. For all particles under study, the experimental Ferguson plots, log(mobility) vs. polymer concentration, permit a linear approximation. Their slope, the retardation coefficient KR = delta log (mobility)/delta (concentration), for particles smaller than 30 nm in diameter increased with particle size in PA-5 and -7 independently of electric field strength and polymer M(r). The KR of particles of 30 nm in diameter or more was found to be independent of particle size at the lowest field strength used but to decrease with it at the higher values of field strength. The decrease was parallel but shifted to higher values of retardation when the polymer M(r) increased from 5 to 7 x 10(6). With a decreasing ratio of average mesh size of the polymer network, zeta, to particle radius, R, the approach to "continuity" of the polymeric medium (zeta/R < 1) with both increasing particle size and polymer concentration does not result in the retardation behavior expected according to the macroscopic (bulk) viscosity of the solution. These experimental observations were hypothetically interpreted in terms of a transition to a retardation mechanism comprising the formation of a polymer depletion layer near the particle surface--polymer solution interface. Peak width exhibited an overall increase with PA-7 concentration for all particles studied. For particles of 30 nm in diameter or less, the increase was steepest when the radius of the particle was approximately commensurate with zeta at a given polymer concentration. For the largest particle, 205 nm in diameter, peak broadening with polymer concentration was found to correlate linearly with peak asymmetry. CZE of

  2. Porcine skin damage thresholds for 0.6 to 9.5 cm beam diameters from 1070-nm continuous-wave infrared laser radiation.

    PubMed

    Vincelette, Rebecca; Noojin, Gary D; Harbert, Corey A; Schuster, Kurt J; Shingledecker, Aurora D; Stolarski, Dave; Kumru, Semih S; Oliver, Jeffrey W

    2014-03-01

    There is an increasing use of high-power fiber lasers in manufacturing and telecommunications industries operating in the infrared spectrum between 1000 and 2000 nm, which are advertised to provide as much as 10 kW continuous output power at 1070 nm. Safety standards have traditionally been based on experimental and modeling investigations with scant data available for these wavelengths. A series of studies using 1070-nm infrared lasers to determine the minimum visible lesion damage thresholds in skin using the Yucatan miniature pig (Sus scrofa domestica) for a range of beam diameters (0.6, 1.1, 1.9, 2.4, 4.7, and 9.5 cm) and a range of exposure durations (10 ms to 10 s) is presented. Experimental peak temperatures associated with each damage threshold were measured using thermal imaging. Peak temperatures at damage threshold for the 10-s exposures were ∼10°C lower than those at shorter exposures. The lowest and highest experimental minimum visible lesion damage thresholds were found to have peak radiant exposures of 19 and 432  J/cm2 for the beam diameter-exposure duration pairs of 2.4 cm, 25 ms and 0.6 cm, 10 s, respectively. Thresholds for beam diameters >2.5  cm had a weak to no effect on threshold radiant exposure levels for exposure times ≤0.25  s, but may have a larger effect on thresholds for exposures ≥10  s. PMID:24658776

  3. Observation of Peierls transition in nanowires (diameter approximately 130 nm) of the charge transfer molecule TTF-TCNQ synthesized by electric-field-directed growth.

    PubMed

    Sai, T Phanindra; Raychaudhuri, A K

    2010-01-29

    We report the growth of nanowires of the charge transfer complex tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) with diameters as low as 130 nm and show that such nanowires can show Peierls transitions at low temperatures. The wires of sub-micron length were grown between two prefabricated electrodes (with sub-micron gap) by vapor phase growth from a single source by applying an electric field between the electrodes during the growth process. The nanowires so grown show a charge transfer ratio approximately 0.57, which is close to that seen in bulk crystals. Below the transition the transport is strongly nonlinear and can be interpreted as originating from de-pinning of CDW that forms at the Peierls transition. PMID:20009165

  4. Observation of Peierls transition in nanowires (diameter~130 nm) of the charge transfer molecule TTF-TCNQ synthesized by electric-field-directed growth

    NASA Astrophysics Data System (ADS)

    Phanindra Sai, T.; Raychaudhuri, A. K.

    2010-01-01

    We report the growth of nanowires of the charge transfer complex tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) with diameters as low as 130 nm and show that such nanowires can show Peierls transitions at low temperatures. The wires of sub-micron length were grown between two prefabricated electrodes (with sub-micron gap) by vapor phase growth from a single source by applying an electric field between the electrodes during the growth process. The nanowires so grown show a charge transfer ratio ~0.57, which is close to that seen in bulk crystals. Below the transition the transport is strongly nonlinear and can be interpreted as originating from de-pinning of CDW that forms at the Peierls transition.

  5. Electrospray synthesis of monodisperse polymer particles in a broad (60 nm-2 μm) diameter range: guiding principles and formulation recipes.

    PubMed

    Almería, Begoña; Gomez, Alessandro

    2014-03-01

    This study reports on a methodology to control the size of polymer particles generated by the electrospray (ES) drying route, with emphasis on the generation of biodegradable polymer nanoparticles that are well suited for biomedical applications. The ability to produce spherical poly(lactic-co-glycolic) acid (PLGA) particles with and without encapsulated active agent, with relative standard deviation not exceeding 15%, was demonstrated over a remarkably broad (60 nm-2 μm) diameter range. By judiciously choosing ES parameters and solution properties, we can control the monodispersity and the size of the obtained particles, tailoring it to a specific application. The main parameters affecting particle size include solution electrical conductivity, flow rate and initial polymer volume fraction. Quasi-monodispersity at both the micro- and the more challenging nano-scale was achieved by avoiding Coulomb fission in the spray droplets, via entanglement of the polymer chains within the droplets rather than by charge neutralization. Guiding principles in the formulation of the solutions to satisfy a multiplicity of constraints are provided along with an extensive database of "recipes". PMID:24407667

  6. Bacillus subtilis Bactofilins Are Essential for Flagellar Hook- and Filament Assembly and Dynamically Localize into Structures of Less than 100 nm Diameter underneath the Cell Membrane

    PubMed Central

    El Andari, Jihad; Altegoer, Florian; Bange, Gert; Graumann, Peter L.

    2015-01-01

    Bactofilins are a widely conserved protein family implicated in cell shape maintenance and in bacterial motility. We show that the bactofilins BacE and BacF from Bacillus subtilis are essential for motility. The proteins are required for the establishment of flagellar hook- and filament structures, but apparently not for the formation of basal bodies. Functional YFP fusions to BacE and to BacF localize as discrete assemblies at the B. subtilis cell membrane, and have a diameter of 60 to 70 nm. BacF assemblies are relatively static, and partially colocalize with flagellar basal bodies, while BacE assemblies are fewer per cell than those of BacF and are highly mobile. Tracking of BacE foci showed that the assemblies arrest at a single point for a few hundred milliseconds, showing that a putative interaction with flagellar structures would be transient and fast. When overexpressed or expressed in a heterologous cell system, bactofilins can form filamentous structures, and also form multimers as purified proteins. Our data reveal a propensity for bactofilins to form filaments, however, in B. subtilis cells, bactofilins assemble into defined size assemblies that show a dynamic localization pattern and play a role in flagellar assembly. PMID:26517549

  7. Conformal SiO2 coating of sub-100 nm diameter channels of polycarbonate etched ion-track channels by atomic layer deposition

    PubMed Central

    Sobel, Nicolas; Lukas, Manuela; Spende, Anne; Stühn, Bernd; Trautmann, Christina

    2015-01-01

    Summary Polycarbonate etched ion-track membranes with about 30 µm long and 50 nm wide cylindrical channels were conformally coated with SiO2 by atomic layer deposition (ALD). The process was performed at 50 °C to avoid thermal damage to the polymer membrane. Analysis of the coated membranes by small angle X-ray scattering (SAXS) reveals a homogeneous, conformal layer of SiO2 in the channels at a deposition rate of 1.7–1.8 Å per ALD cycle. Characterization by infrared and X-ray photoelectron spectroscopy (XPS) confirms the stoichiometric composition of the SiO2 films. Detailed XPS analysis reveals that the mechanism of SiO2 formation is based on subsurface crystal growth. By dissolving the polymer, the silica nanotubes are released from the ion-track membrane. The thickness of the tube wall is well controlled by the ALD process. Because the track-etched channels exhibited diameters in the range of nanometres and lengths in the range of micrometres, cylindrical tubes with an aspect ratio as large as 3000 have been produced. PMID:25821688

  8. A study of improved MHR 50/100 toward a higher level of inherent safety

    SciTech Connect

    Minatsuki, I.; Otani, T.; Shimizu, K.; Oyama, S.; Tsukamoto, H.; Kunitomi, K.

    2012-07-01

    A new concept of the Mitsubishi small-sized High temperature gas-cooled modular Reactors (MHR-50/100) had been developed and published in papers. The study results of the first design concept show that the MHR-50/100 can achieve the inherent safety level set as a design target in case of water ingress during steam generator tube rupture accident. And more specifically, the reactor was shown to remain stable during long-term station black out (SBO) with protection of only passive devices during a depressurization accident and with additional motion of steam dump system during a water ingress accident. Recently greater requirements for safety of future nuclear plants including the MHR-50/100 have been expected. This study has thus made a key design improvement for the MHR-50/100 in order to secure the inherent safety aspect without reliance on active steam dump system in case of a water ingress accident. The innovative technologies listed below have been created and investigated to achieve the improved MHR-50/100 design; (1) Design improvement of steam generator, (2) Heat balance optimization of steam cycle, (3) Control system design of differential pressure between primary helium gas and water/steam, (4) Study on operation procedure during a water ingress accident. (authors)

  9. Commissioning a 50-100 kV X-ray unit for skin cancer treatment.

    PubMed

    Sheu, Ren-Dih; Powers, Allison; Lo, Yeh-Chi

    2015-01-01

    This study provides the authors' experience along with dosimetric data from the commissioning of two Sensus SRT-100 50-100 kV X-ray units. Data collected during the commissioning process included: a) HVL, b) output (dose rate), c) applicator cone factors, and d) percentage depth dose. A Farmer-type chamber (PTW-N23333), and a thin-window parallel plate ion chamber (PTW-N23342) were used for dose rate measurements and dose profiles were measured with EBT3 GafChromic film. The average HVL values for 50, 70, and 100 kV of the two treatment units were found to be 0.52, 1.15, and 2.20 mm Al, respectively. The HVL's were 5%-9% lower when measured with the Farmer chamber, as compared to measurements with the parallel plate chamber, for energies of 70 and 100 kV. Dose rates were also measured to be 3%-4% lower with the Farmer chamber. The dose rate variation between the two units was found to be 2%-9% for 50, 70, and 100 kV. The dose uniformity over a circle of 2 cm diameter was within 4% in four cardinal directions; however, the dose profiles for the 5 cm applicator were nonuniform, especially in the cathode-anode direction. Measurements indicated as much as 15% lower dose for the 50 kV beam at field edge on the anode side, when normalized to the center. The crossline profile was relatively more symmetric, with a maximum deviation of 10% at the field edge. All ion chamber readings agreed with film measurements within 3%. The nonuniform profile produced by these units may introduce uncertainty in dose rate measurements, especially for larger applicators. Since there is no intrinsic tool (crosshair or field light) for alignment with the beam axis, the user should take care when positioning the chamber for output measurements. The data obtained with a Farmer-type chamber should be used cautiously and as a reference only for the SRT-100 X-ray treatment unit. PMID:26103186

  10. Conceptual definition of a 50-100 kWe NEP system for planetary science missions

    NASA Technical Reports Server (NTRS)

    Friedlander, Alan

    1993-01-01

    The Phase 1 objective of this project is to assess the applicability of a common Nuclear Electric Propulsion (NEP) flight system of the 50-100 kWe power class to meet the advanced transportation requirements of a suite of planetary science (robotic) missions, accounting for differences in mission-specific payloads and delivery requirements. The candidate missions are as follows: (1) Comet Nucleus Sample Return; (2) Multiple Mainbelt Asteroid Rendezvous; (3) Jupiter Grand Tour (Galilean satellites and magnetosphere); (4) Uranus Orbiter/Probe (atmospheric entry and landers); (5) Neptune Orbiter/Probe (atmospheric entry and landers); and (6) Pluto-Charon Orbiter/Lander. The discussion is presented in vugraph form.

  11. Conceptual definition of a 50-100 kWe NEP system for planetary science missions

    NASA Astrophysics Data System (ADS)

    Friedlander, Alan

    The Phase 1 objective of this project is to assess the applicability of a common Nuclear Electric Propulsion (NEP) flight system of the 50-100 kWe power class to meet the advanced transportation requirements of a suite of planetary science (robotic) missions, accounting for differences in mission-specific payloads and delivery requirements. The candidate missions are as follows: (1) Comet Nucleus Sample Return; (2) Multiple Mainbelt Asteroid Rendezvous; (3) Jupiter Grand Tour (Galilean satellites and magnetosphere); (4) Uranus Orbiter/Probe (atmospheric entry and landers); (5) Neptune Orbiter/Probe (atmospheric entry and landers); and (6) Pluto-Charon Orbiter/Lander. The discussion is presented in vugraph form.

  12. Tailoring morphology in free-standing anodic aluminium oxide: control of barrier layer opening down to the sub-10 nm diameter.

    PubMed

    Gong, Jie; Butler, William H; Zangari, Giovanni

    2010-05-01

    Free-standing, highly ordered porous aluminium oxide templates were fabricated by three-step anodization in oxalic, sulfuric or phosphoric acid solutions, followed by dissolution of the aluminium substrate in HgCl(2). Opening of the pore bottoms on the barrier layer side of these templates was carried out by using chemical or ion beam etching. Chemical etching is capable of achieving full pore opening, but partial pore opening occurs inhomogeneously. On the contrary, ion beam etching enables homogeneous and reproducible partial pore opening, with the pore size controlled through the etching time. By this method, pore openings as small as 5 nm can reliably be obtained. PMID:20648324

  13. A 50-100 kWe gas-cooled reactor for use on Mars.

    SciTech Connect

    Peters, Curtis D.

    2006-04-01

    In the space exploration field there is a general consensus that nuclear reactor powered systems will be extremely desirable for future missions to the outer solar system. Solar systems suffer from the decreasing intensity of solar radiation and relatively low power density. Radioisotope Thermoelectric Generators are limited to generating a few kilowatts electric (kWe). Chemical systems are short-lived due to prodigious fuel use. A well designed 50-100 kWe nuclear reactor power system would provide sufficient power for a variety of long term missions. This thesis will present basic work done on a 50-100 kWe reactor power system that has a reasonable lifespan and would function in an extraterrestrial environment. The system will use a Gas-Cooled Reactor that is directly coupled to a Closed Brayton Cycle (GCR-CBC) power system. Also included will be some variations on the primary design and their effects on the characteristics of the primary design. This thesis also presents a variety of neutronics related calculations, an examination of the reactor's thermal characteristics, feasibility for use in an extraterrestrial environment, and the reactor's safety characteristics in several accident scenarios. While there has been past work for space reactors, the challenges introduced by thin atmospheres like those on Mars have rarely been considered.

  14. Conceptual Design of a 50--100 MW Electron Beam Accelerator System for the National Hypersonic Wind Tunnel Program

    SciTech Connect

    SCHNEIDER,LARRY X.

    2000-06-01

    The National Hypersonic Wind Tunnel program requires an unprecedented electron beam source capable of 1--2 MeV at a beam power level of 50--100 MW. Direct-current electron accelerator technology can readily generate high average power beams to approximately 5 MeV at output efficiencies greater than 90%. However, due to the nature of research and industrial applications, there has never been a requirement for a single module with an output power exceeding approximately 500 kW. Although a 50--100 MW module is a two-order extrapolation from demonstrated power levels, the scaling of accelerator components appears reasonable. This paper presents an evaluation of component and system issues involved in the design of a 50--100 MW electron beam accelerator system with precision beam transport into a high pressure flowing air environment.

  15. Improvement design study on steam generator of MHR-50/100 aiming higher safety level after water ingress accident

    SciTech Connect

    Oyama, S.; Minatsuki, I.; Shimizu, K.

    2012-07-01

    Mitsubishi Heavy Industries, Ltd. (MHI) has been studying on MHI original High Temperature Gas cooled Reactor (HTGR), namely MHR-50/100, for commercialization with supported by JAEA. In the heat transfer system, steam generator (SG) is one of the most important components because it should be imposed a function of heat transfer from reactor power to steam turbine system and maintaining a nuclear grade boundary. Then we especially focused an effort of a design study on the SG having robustness against water ingress accident based on our design experience of PWR, FBR and HTGR. In this study, we carried out a sensitivity analysis from the view point of economic and plant efficiency. As a result, the SG design parameter of helium inlet/outlet temperature of 750 deg. C/300 deg. C, a side-by-side layout and one unit of SG attached to a reactor were selected. In the next, a design improvement of SG was carried out from the view point of securing the level of inherent safety without reliance on active steam dump system during water ingress accident considering the situation of the Fukushima nuclear power plant disaster on March 11, 2011. Finally, according to above basic design requirement to SG, we performed a conceptual design on adapting themes of SG structure improvement. (authors)

  16. REE Sorption Study of Seived -50 +100 Mesh Fraction of Media #1 in Brine #1 at Different Concentrations of REE at 70C

    SciTech Connect

    Gary Garland

    2015-06-29

    This dataset shows the sorption capacities of smaller grain size (-50 +100 mesh) of media #1 in brine #1 at different starting concentrations of REE's at elevated temperature of 70C. The experimental conditions are 2g of -50 +100 mesh media #1 to 150mL of REE solution at concentartions of .2ppm each, 2ppm each, and 20ppm each. The pH of the solution is 5.5, and the temperature was at 70C.

  17. REE Sorption Study of Sieved -50 +100 mesh Media #1 in Brine #1 with Different Starting pH's at 70C

    SciTech Connect

    Gary Garland

    2015-07-21

    This dataset described shaker table experiments ran with sieved -50 +100 mesh media #1 in brine #1 that have 2ppm each of the 7 REE metals at different starting pH's of 3.5, 4.5, and 5.5. The experimental conditions are 2g media to 150mL of REE solution, at 70C.

  18. Hour-long continuous operation of a tabletop soft x-ray laser at 50-100 Hz repetition rate.

    PubMed

    Reagan, Brendan A; Li, Wei; Urbanski, Lukasz; Wernsing, Keith A; Salsbury, Chase; Baumgarten, Cory; Marconi, Mario C; Menoni, Carmen S; Rocca, Jorge J

    2013-11-18

    We report the uninterrupted operation of an 18.9 nm wavelength tabletop soft x-ray laser at 100 Hz repetition rate for extended periods of time. An average power of about 0.1 mW was obtained by irradiating a Mo target with pulses from a compact diode-pumped chirped pulse amplification Yb:YAG laser. Series of up to 1.8 x 10(5) consecutive laser pulses of ~1 µJ energy were generated by displacing the surface of a high shot-capacity rotating molybdenum target by ~2 µm between laser shots. As a proof-of-principle demonstration of the use of this compact ultrashort wavelength laser in applications requiring a high average power coherent beam, we lithographically printed an array of nanometer-scale features using coherent Talbot self-imaging. PMID:24514347

  19. Small diameter carbon nanopipettes

    NASA Astrophysics Data System (ADS)

    Singhal, Riju; Bhattacharyya, Sayan; Orynbayeva, Zulfiya; Vitol, Elina; Friedman, Gary; Gogotsi, Yury

    2010-01-01

    Nanoscale multifunctional carbon probes facilitate cellular studies due to their small size, which makes it possible to interrogate organelles within living cells in a minimally invasive fashion. However, connecting nanotubes to macroscopic devices and constructing an integrated system for the purpose of fluid and electrical signal transfer is challenging, as is often the case with nanoscale components. We describe a non-catalytic chemical vapor deposition based method for batch fabrication of integrated multifunctional carbon nanopipettes (CNPs) with tip diameters much smaller (10-30 nm) than previously reported (200 nm and above) and approaching those observed for multiwalled carbon nanotubes. This eliminates the need for complicated attachment/assembly of nanotubes into nanofluidic devices. Variable tip geometries and structures were obtained by controlled deposition of carbon inside and outside quartz pipettes. We have shown that the capillary length and gas flow rate have a marked effect on the carbon deposition. This gives us a flexible protocol, useful for growing carbon layers of different thicknesses at selective locations on a glass pipette to yield a large variety of cellular probes in bulk quantities. The CNPs possess an open channel for fluid transfer with the carbon deposited inside at 875 °C behaving like an amorphous semiconductor. Vacuum annealing of the CNP tips at temperatures up to 2000 °C yields graphitic carbon structures with an increase in conductivity of two orders of magnitude. Penetration of the integrated carbon nanoprobes into cells was shown to produce minimal Ca2+ signals, fast recovery of basal Ca2+ levels and no adverse activation of the cellular metabolism during interrogation times as long as 0.5-1 h.

  20. Interpreting stem diameter changes

    NASA Astrophysics Data System (ADS)

    Hölttä, T.; Sevanto, S.; Nikinmaa, E.

    2009-12-01

    Detecting phloem transport in stem diameter changes Teemu Hölttä1, Sanna Sevanto2, Eero Nikinmaa1 1Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland 2Department of Physics, P.O. Box 48, FIN-00014 University of Helsinki, Finland Introduction The volume of living cells and xylem conduits vary according to pressures they are subjected to. Our proposition is that the behavior of the inner bark diameter variation which cannot be explained by changes in xylem water status arise from changes in the osmotic concentration of the phloem and cambial growth. Materials and methods Simultaneous xylem and stem diameter measurements were conducted between June 28th to October 4th 2006 in Southern Finland on a 47-year old, 15 meter tall, Scots pine tree (DBH 15 cm) at heights of 1.5 and 10 meters. The difference between the measured inner bark diameter and the inner bark diameter predicted from xylem diameter change with a simple model (assuming there was no change in the osmotic concentration of the phloem) is hypothesized to give the changes in the osmotic concentration of the inner bark. The simple model calculates the radial water exchange between the xylem and phloem driven by the water potential changes in the xylem. Results and Discussion The major signal in the inner bark diameter was the transpiration rate as assumed, but also a signal arising from the change in the osmotic concentration (Fig 1a). The predicted osmotic concentration of the phloem typically increased during the afternoon due to the loading of photosynthesized sugars to the phloem. Inner bark osmotic concentration followed the photosynthesis rate with a 3 and 4 hour time-lag at the top and base, respectively (Fig 1b). The connection between photosynthesis and the predicted change in phloem osmotic concentration was stronger in the upper part of the tree compared to lower part. The changes in the predicted osmotic concentration were not similar every day, indicating that

  1. Limitations on the Optical Tunability of Small Diameter Gold Nanoshells

    PubMed Central

    Rasch, Michael R.; Sokolov, Konstantin V.; Korgel, Brian A.

    2009-01-01

    Gold (Au) nanoshells were grown on silica nanoparticles with differing average diameters, ranging from 30 nm to 120 nm. Au nanoshells were also formed on silica spheres encapsulating 5 nm diameter magnetic iron oxide nanocrystals. The optical absorbance spectra of these Au nanoshells are reported. The plasmon resonance wavelengths of the smaller diameter nanoshells were significantly less tunable than those of the larger diameter nanoshells. This is due to a reduced range of accessible core-shell ratio—the geometric factor that determines the plasmon peak position—as the silica core diameter shrinks. The smaller diameter nanoshells were also found to be highly prone to aggregation, which broadens the plasmon absorption peak. Model calculations of dispersion stability as a function of silica core diameter reveal that smaller diameter Au shells exhibit more aggregation because of the size-dependence of the electrostatic double-layer potential. PMID:19711913

  2. Photoacoustic determination of blood vessel diameter

    NASA Astrophysics Data System (ADS)

    Kolkman, Roy G. M.; Klaessens, John H. G. M.; Hondebrink, Erwin; Hopman, Jeroen C. W.; de Mul, Frits F. M.; Steenbergen, Wiendelt; Thijssen, Johan M.; van Leeuwen, Ton G.

    2004-10-01

    A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-to-peak time (tgrpp) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual vessel diameter showed that the diameter could be approximated by 2ctgrpp, with c the speed of sound in blood. Using this relation, the lateral diameter could also precisely be determined. In vivo imaging and monitoring of changes in vessel diameters was feasible. Finally, acoustic time traces were recorded while flushing a vessel in the rabbit ear with saline, which proved that the main contribution to the laser-induced pressure transient is caused by blood inside the vessel and that the vessel wall gives only a minor contribution.

  3. Optical receivers with large-diameter photodiode

    NASA Astrophysics Data System (ADS)

    Swoboda, Robert; Schneider, Kerstin; Zimmermann, Horst

    2006-04-01

    This work presents two types of optical receivers with large-diameter photodiodes. Both are optoelectronic integrated circuits (OEICs) realized in 0.6μm BiCMOS Si technology integrating PIN photodiode, transimpedance amplifier (TIA) and output circuit on chip. The two circuits are an optocoupler with a photodiode diameter of 780μm and a rise- and falltime of 5ns and 4.9ns respectively at 850nm light and a plastic optical fiber (POF) receiver with a photodiode diameter of 500μm and upper -3dB cut-off frequencies of 165MHz at 660nm light and 148MHz at 850nm light. The measured rise- and falltime of the POF receiver was 1.78ns and 2.45ns at 660nm light and 1.94ns and 2.5ns at 850ns, respectively. The presented results combine the advantage of easier handling of large-diameter photodiode receivers and high performance.

  4. Snow accumulation rate on Qomolangma (Mount Everest), Himalaya: synchroneity with sites across the Tibetan Plateau on 50-100 year timescales

    NASA Astrophysics Data System (ADS)

    Kaspari, Susan; Hooke, Roger Leb.; Mayewski, Paul Andrew; Kang, Shichang; Hou, Shugui; Qin, Dahe

    Annual-layer thickness data, spanning AD 1534-2001, from an ice core from East Rongbuk Col on Qomolangma (Mount Everest, Himalaya) yield an age-depth profile that deviates systematically from a constant accumulation-rate analytical model. The profile clearly shows that the mean accumulation rate has changed every 50-100 years. A numerical model was developed to determine the magnitude of these multi-decadal-scale rates. The model was used to obtain a time series of annual accumulation. The mean annual accumulation rate decreased from ˜0.8 m ice equivalent in the 1500s to ˜0.3 m in the mid-1800s. From ˜1880 to ˜1970 the rate increased. However, it has decreased since ˜1970. Comparison with six other records from the Himalaya and the Tibetan Plateau shows that the changes in accumulation in East Rongbuk Col are broadly consistent with a regional pattern over much of the Plateau. This suggests that there may be an overarching mechanism controlling precipitation and mass balance over this area. However, a record from Dasuopu, only 125 km northwest of Qomolangma and 700 m higher than East Rongbuk Col, shows a maximum in accumulation during the 1800s, a time during which the East Rongbuk Col and Tibetan Plateau ice-core and tree-ring records show a minimum. This asynchroneity may be due to altitudinal or seasonal differences in monsoon versus westerly moisture sources or complex mountain meteorology.

  5. 469nm Fiber Laser Source

    SciTech Connect

    Drobshoff, A; Dawson, J W; Pennington, D M; Payne, S A; Beach, R

    2005-01-20

    We have demonstrated 466mW of 469nm light from a frequency doubled continuous wave fiber laser. The system consisted of a 938nm single frequency laser diode master oscillator, which was amplified in two stages to 5 Watts using cladding pumped Nd{sup 3+} fiber amplifiers and then frequency doubled in a single pass through periodically poled KTP. The 3cm long PPKTP crystal was made by Raicol Crystals Ltd. with a period of 5.9 {micro}m and had a phase match temperature of 47 degrees Centigrade. The beam was focused to a 1/e{sup 2} diameter in the crystal of 29 {micro}m. Overall conversion efficiency was 11% and the results agreed well with standard models. Our 938nm fiber amplifier design minimizes amplified spontaneous emission at 1088nm by employing an optimized core to cladding size ratio. This design allows the 3-level transition to operate at high inversion, thus making it competitive with the 1088nm 4-level transition. We have also carefully chosen the fiber coil diameter to help suppress propagation of wavelengths longer than 938 nm. At 2 Watts, the 938nm laser had an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >10:1).

  6. Double diameter boring tool

    DOEpatents

    Ashbaugh, F.A.; Murry, K.R.

    1986-02-10

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting flutes formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first flute tip to the axis of rotation plus the distance from the second flute tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second flute tip to the axis of rotation minus one-half the distance from the first flute tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  7. Double diameter boring tool

    DOEpatents

    Ashbaugh, Fred N.; Murry, Kenneth R.

    1988-12-27

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting edges formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first cutting edge tip to the axis of rotation plus the distance from the second cutting edge tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second cutting edge tip to the axis of rotation minus one-half the distance from the first cutting edge tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  8. Submicron diameter single crystal sapphire optical fiber

    SciTech Connect

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers is the first step in achieving optical and sensing performance on par with its fused silica counterpart.

  9. Submicron diameter single crystal sapphire optical fiber

    DOE PAGESBeta

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers ismore » the first step in achieving optical and sensing performance on par with its fused silica counterpart.« less

  10. The DIAMET campaign

    NASA Astrophysics Data System (ADS)

    Vaughan, G.

    2012-04-01

    DIAMET (DIAbatic influences on Mesoscale structures in ExTratropical storms) is a joint project between the UK academic community and the Met Office. Its focus is on understanding and predicting mesoscale structures in synoptic-scale storms, and in particular on the role of diabatic processes in generating and maintaining them. Such structures include fronts, rain bands, secondary cyclones, sting jets etc, and are important because much of the extreme weather we experience (e.g. strong winds, heavy rain) comes from such regions. The project conducted two field campaigns in the autumn of 2011, from September 14 - 30 and November 24 - December 14, based around the FAAM BAe146 aircraft with support from ground-based radar and radiosonde measurements. Detailed modelling, mainly using the Met Office Unified model, supported the planning and interpretation of these campaigns. This presentation will give a brief overview of the campaigns. Both in September and November-December the weather regime was westerly, with a strong jet stream directed across the Atlantic. Three IOPs were conducted in September, to observe a convective band ahead of an upper-level trough, waves on a long trailing cold front, and a warm conveyor belt associated with a secondary cyclone. In November-December six IOPs were conducted, to observe frontal passages and high winds. This period was notable for a number of very strong windstorms passing across the north of the UK, and gave us an opportunity to examine bent-back warm fronts in the southern quadrant of these storms where the strongest winds are found. The case studies fell into two basic patterns. In the majority of cases, dropsonde legs at high level were used to obtain a cross-section of winds and thermodynamic structure (e.g. across a front), followed by in situ legs at lower levels (generally where the temperature was between 0 and -10°) to examine microphysical processes, especially ice multiplication and the extent of supercooled water

  11. Diameter Controlled of Carbon Nanotubes Synthesized on Nanoporous Silicon Support

    NASA Astrophysics Data System (ADS)

    Asli, N. A.; Shamsudin, M. S.; Maryam, M.; Yusop, S. F. M.; Suriani, A. B.; Rusop, M.; Abdullah, S.

    2013-06-01

    Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

  12. Wheel Diameter and Speedometer Reading

    ERIC Educational Resources Information Center

    Murray, Clifton

    2010-01-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it…

  13. Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

    DOE PAGESBeta

    Andelman, Tamar; Gong, Yinyan; Neumark, Gertrude; O'Brien, Stephen

    2007-01-01

    A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm) nanorods were synthesized from trihexylamine, and large diameter (50–80 nm) nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green) emission of the photoluminescence (PL) spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

  14. Measuring Diameters Of Large Vessels

    NASA Technical Reports Server (NTRS)

    Currie, James R.; Kissel, Ralph R.; Oliver, Charles E.; Smith, Earnest C.; Redmon, John W., Sr.; Wallace, Charles C.; Swanson, Charles P.

    1990-01-01

    Computerized apparatus produces accurate results quickly. Apparatus measures diameter of tank or other large cylindrical vessel, without prior knowledge of exact location of cylindrical axis. Produces plot of inner circumference, estimate of true center of vessel, data on radius, diameter of best-fit circle, and negative and positive deviations of radius from circle at closely spaced points on circumference. Eliminates need for time-consuming and error-prone manual measurements.

  15. Wheel Diameter and Speedometer Reading

    NASA Astrophysics Data System (ADS)

    Murray, Clifton

    2010-09-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it makes a good illustration of how reasoning in physics can lead to a result that is useful outside the classroom.

  16. Diameter-dependent hydrophobicity in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kyakuno, Haruka; Fukasawa, Mamoru; Ichimura, Ryota; Matsuda, Kazuyuki; Nakai, Yusuke; Miyata, Yasumitsu; Saito, Takeshi; Maniwa, Yutaka

    2016-08-01

    Single-wall carbon nanotubes (SWCNTs) are a good model system that provides atomically smooth nanocavities. It has been reported that water-SWCNTs exhibit hydrophobicity depending on the temperature T and the SWCNT diameter D. SWCNTs adsorb water molecules spontaneously in their cylindrical pores around room temperature, whereas they exhibit a hydrophilic-hydrophobic transition or wet-dry transition (WDT) at a critical temperature Twd ≈ 220-230 K and above a critical diameter Dc ≈ 1.4-1.6 nm. However, details of the WDT phenomenon and its mechanism remain unknown. Here, we report a systematic experimental study involving X-ray diffraction, optical microscopy, and differential scanning calorimetry. It is found that water molecules inside thick SWCNTs (D > Dc) evaporate and condense into ice Ih outside the SWCNTs at Twd upon cooling, and the ice Ih evaporates and condenses inside the SWCNTs upon heating. On the other hand, residual water trapped inside the SWCNTs below Twd freezes. Molecular dynamics simulations indicate that upon lowering T, the hydrophobicity of thick SWCNTs increases without any structural transition, while the water inside thin SWCNTs (D < Dc) exhibits a structural transition, forming an ordered ice. This ice has a well-developed hydrogen bonding network adapting to the cylindrical pores of the SWCNTs. Thus, the unusual diameter dependence of the WDT is attributed to the adaptability of the structure of water to the pore dimension and shape.

  17. Stellar diameters and temperatures. IV. Predicting stellar angular diameters

    SciTech Connect

    Boyajian, Tabetha S.; Van Belle, Gerard; Von Braun, Kaspar

    2014-03-01

    The number of stellar angular diameter measurements has greatly increased over the past few years due to innovations and developments in the field of long baseline optical interferometry. We use a collection of high-precision angular diameter measurements for nearby, main-sequence stars to develop empirical relations that allow the prediction of stellar angular sizes as a function of observed photometric color. These relations are presented for a combination of 48 broadband color indices. We empirically show for the first time a dependence on metallicity of these relations using Johnson (B – V) and Sloan (g – r) colors. Our relations are capable of predicting diameters with a random error of less than 5% and represent the most robust and empirical determinations of stellar angular sizes to date.

  18. Sub-10 nm nanopantography

    SciTech Connect

    Tian, Siyuan Donnelly, Vincent M. E-mail: economou@uh.edu; Economou, Demetre J. E-mail: economou@uh.edu; Ruchhoeft, Paul

    2015-11-09

    Nanopantography, a massively parallel nanopatterning method over large areas, was previously shown to be capable of printing 10 nm features in silicon, using an array of 1000 nm-diameter electrostatic lenses, fabricated on the substrate, to focus beamlets of a broad area ion beam on selected regions of the substrate. In the present study, using lens dimensional scaling optimized by computer simulation, and reduction in the ion beam image size and energy dispersion, the resolution of nanopantography was dramatically improved, allowing features as small as 3 nm to be etched into Si.

  19. Nanofiber alignment of a small diameter elastic electrospun scaffold

    NASA Astrophysics Data System (ADS)

    Patel, Jignesh

    Cardiovascular disease is the leading cause of death in western countries with coronary heart disease making up 50% of these deaths. As a treatment option, tissue engineered grafts have great potential. Elastic scaffolds that mimic arterial extracellular matrix (ECM) may hold the key to creating viable vascular grafts. Electrospinning is a widely used scaffold fabrication technique to engineer tubular scaffolds. In this study, we investigated how the collector rotation speed altered the nanofiber alignment which may improve mechanical characteristics making the scaffold more suitable for arterial grafts. The scaffold was fabricated from a blend of PCL/Elastin. 2D Fast Fourier Transform (FFT) image processing tool and MatLab were used to quantitatively analyze nanofiber orientation at different collector speeds (13500 to 15500 rpm). Both Image J and MatLab showed graphical peaks indicating predominant fiber orientation angles. A collector speed of 15000 rpm was found to produce the best nanofiber alignment with narrow peaks at 90 and 270 degrees, and a relative amplitude of 200. This indicates a narrow distribution of circumferentially aligned nanofibers. Collector speeds below and above 15000 rpm caused a decrease in fiber alignment with a broader orientation distribution. Uniformity of fiber diameter was also measured. Of 600 measures from the 15000 rpm scaffolds, the fiber diameter range from 500 nm to 899 nm was most prevalent. This diameter range was slightly larger than native ECM which ranges from 50 nm to 500 nm. The second most prevalent diameter range had an average of 404 nm which is within the diameter range of collagen. This study concluded that with proper electrospinning technique and collector speed, it is possible to fabricate highly aligned small diameter elastic scaffolds. Image J 2D FFT results confirmed MatLab findings for the analyses of circumferentially aligned nanofibers. In addition, MatLab analyses simplified the FFT orientation data

  20. High voltage variable diameter insulator

    DOEpatents

    Vanacek, D.L.; Pike, C.D.

    1982-07-13

    A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

  1. Assembly of gold nanoparticles of different diameters between nanogap electrodes

    SciTech Connect

    Cheon, Donguk; Kumar, Sanjeev; Kim, Gil-Ho

    2010-01-04

    Gold nanoparticles (NPs) of different diameters i.e., 5, 10, and 20 nm, were assembled between 20 nm gap electrodes using ac dielectrophoresis (DEP) process. DEP parameters, such as frequency, trapping time, and voltage of value 1 MHz, 1 s, and 2-3 V, respectively, led to the pearl-chain assembly corresponding to each type of NPs between 20 nm gap electrodes. Mutual DEP could be attributed to the NPs chaining in low field regions and subsequently the DEP force directs these chains to the trapping region. Such controlled assembly of individual NPs may find application in fabricating devices for molecular electronics.

  2. High voltage variable diameter insulator

    DOEpatents

    Vanecek, David L.; Pike, Chester D.

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  3. Effect of Diethylenetriamine and Triethylamine sensitization on the critical diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Lee, J. J.; Jiang, J.; Choong, K. H.; Lee, J. H. S.

    2000-04-01

    In this work, the critical diameter for detonation was measured for Nitromethane (NM) sensitized with two different amines: Diethylenetriamine (DETA) and Triethylamine (TEA). The critical diameter in glass and polyvinylchloride tubes is found to decrease rapidly as the amount of sensitizer is increased, then increase past a critical amount of sensitizer. Thus the critical diameter reaches a minimum at a critical concentration of sensitizer. It was also found that the critical diameter is lower with DETA than with TEA.

  4. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  5. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  6. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a...

  7. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a...

  8. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  9. Comparison of Failure Thickness and Critical Diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.; Higgins, Andrew J.

    2006-07-01

    The critical diameter and failure thickness of both neat liquid nitromethane and a 65% nitromethane/35% nitroethane blend confined by aluminum are determined experimentally. A comparison of these two parameters provides insight into the failure mechanism of detonation in these explosives. If the failure of detonation in a critical charge diameter (or thickness) experiment is due to reaction quenching resulting from expansion losses (wave curvature), then it is expected that the failure thickness should be half the value of the critical diameter. The critical diameter and failure thickness of neat nitromethane confined in aluminum are found to be 2.5 mm and 0.75 mm respectively for a temperature range of 26 ± 1°C. The critical diameter and failure thickness of the 65NM/35NE blend confined in aluminum are found to be 6.2 mm and 1.7 mm respectively for a temperature range of 28 ± 1°C. The ratio of critical diameter to failure thickness for these experiments is found to lie between 3:1 and 4:1 rather than 2:1 as expected from wave curvature theory. By comparing the experimentally determined values of critical diameter and thickness for the test explosives and examining the failure patterns recovered on witness plates, a mechanism of propagation in thin rectangular channels is proposed based on complex wave interactions.

  10. UV - ALBUQUERQUE NM

    EPA Science Inventory

    Brewer 109 is located in Albuquerque NM, measuring ultraviolet solar radiation. Irradiance and column ozone are derived from this data. Ultraviolet solar radiation is measured with a Brewer Mark IV, single-monochrometer, spectrophotometer manufactured by SCI-TEC Instruments, Inc....

  11. Diameter Dependence of the Transport Properties of Antimony Telluride Nanowires

    NASA Astrophysics Data System (ADS)

    Zuev, Yuri; Lee, Jin Sook; Park, Hongkun; Kim, Philip

    2010-03-01

    We report measurements of electronic, thermoelectric, and galvanometric properties of individual semimetallic single crystal antimony telluride (Sb2Te3) nanowires. Microfabricated heater and thermometer electrodes were used to probe the transport properties of the nanowires with diameters in the range of 22 - 95nm and temperatures in the range of 2 - 300K. Temperature dependent resistivity varies depending on nanowire diameter. Thermoelectric power (TEP) measurements indicate hole dominant diffusive thermoelectric generation, with an enhancement of the TEP for smaller diameter wires. The large surface-to-volume ratio of Sb2Te3 nanowires makes them an excellent platform to explore novel phenomena in this predicted topological insulator. We investigate mesoscopic magnetoresistance effects in magnetic fields both parallel and perpendicular to the nanowire axis.

  12. Albuquerque, NM, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Albuquerque, NM (35.0N, 106.5W) is situated on the edge of the Rio Grande River and flood plain which cuts across the image. The reddish brown surface of the Albuquerque Basin is a fault depression filled with ancient alluvial fan and lake bed sediments. On the slopes of the Manzano Mountains to the east of Albuquerque, juniper and other timber of the Cibola National Forest can be seen as contrasting dark tones of vegetation.

  13. Diameter dependent thermoelectric properties of individual SnTe nanowires

    DOE PAGESBeta

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowiremore » diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.« less

  14. Diameter dependent thermoelectric properties of individual SnTe nanowires

    SciTech Connect

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowire diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.

  15. Diameter dependent thermoelectric properties of individual SnTe nanowires.

    PubMed

    Xu, E Z; Li, Z; Martinez, J A; Sinitsyn, N; Htoon, H; Li, Nan; Swartzentruber, B; Hollingsworth, J A; Wang, Jian; Zhang, S X

    2015-02-21

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a promising thermoelectric material. In this work, we report on the first thermoelectric study of individual single-crystalline SnTe nanowires with different diameters ranging from ∼218 to ∼913 nm. Measurements of thermopower S, electrical conductivity σ and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25-300 K. While the electrical conductivity does not show a strong diameter dependence, the thermopower increases by a factor of two when the nanowire diameter is decreased from ∼913 nm to ∼218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may arise from the enhanced phonon - surface boundary scattering and phonon-defect scattering. Temperature dependent figure of merit ZT was determined for individual nanowires and the achieved maximum value at room temperature is about three times higher than that in bulk samples of comparable carrier density. PMID:25623253

  16. Diameter and wall number control of carbon nanotubes by chemical vapor deposition

    SciTech Connect

    Xie, Rongsi; Zhong, Guofang Zhang, Can; Chen, Bingan; Santiago Esconjauregui, C.; Robertson, John

    2013-12-28

    We analyze the relationship between the average wall number (N) and the diameter (d) for carbon nanotubes (CNTs) grown by chemical vapour deposition. It is found that N depends linearly on d for diameters in the range of 2.5–10 nm, while single wall nanotubes predominate for diameters under about 2.1 nm. The linear relationship is found to depend somewhat on the growth conditions. It is also verified that the mean diameter depends on the diameter of the originating catalyst nanoparticle, and thus on the initial catalyst thickness where a thin film catalyst is used. This simplifies the characterisation of CNTs by electron microscopy. We also find a linear relationship between nanotube diameter and initial catalyst film thickness.

  17. Guided proliferation and bone-forming functionality on highly ordered large diameter TiO2 nanotube arrays.

    PubMed

    Zhang, Ruopeng; Wu, Hongliu; Ni, Jiahua; Zhao, Changli; Chen, Yifan; Zheng, Chengjunyi; Zhang, Xiaonong

    2015-08-01

    The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO2 nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO2 nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO2 nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO2 nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO2 nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO2 nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100-200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO2 nanotubes. PMID:26042715

  18. Biosensing using plasmonic nanohole arrays with small, homogenous and tunable aperture diameters.

    PubMed

    Xiong, Kunli; Emilsson, Gustav; Dahlin, Andreas B

    2016-06-21

    Plasmonic nanohole arrays are widely used for optical label-free molecular detection. An important factor for many applications is the diameter of the apertures. So far nanohole arrays with controllable diameters below 100 nm have not been demonstrated and it has not been systematically investigated how the diameter influences the optical properties. In this work we fine-tune the diameter in short range ordered nanohole arrays down to 50 nm. The experimental far field spectra show how the wavelength of maximum extinction remains unaffected while the transmission maximum blue shifts with smaller diameters. The near field is visualized by numerical simulations, showing a homogenous enhancement throughout the cylindrical void at the transmission maximum for diameters between 50 and 100 nm. For diameters below 50 nm plasmon excitation is no longer possible experimentally or by simulations. Further, we investigate the refractive index sensing capabilities of the smaller holes. As the diameter was reduced, the sensitivity in terms of resonance shift with bulk liquid refractive index was found to be unaltered. However, for the transmission maximum the sensitivity becomes more strongly localized to the hole interior. By directing molecular binding to the bottom of the holes we demonstrate how smaller holes enhance the sensitivity in terms of signal per molecule. A real-time detection limit well below one protein per nanohole is demonstrated. The smaller plasmonic nanoholes should be suitable for studies of molecules confined in small volumes and as mimics of biological nanopores. PMID:26867475

  19. Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights

    SciTech Connect

    Razek, Sara Abdel; Swillam, Mohamed A.; Allam, Nageh K.

    2014-05-21

    Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H{sub 2}O{sub 2} electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650 nm and lengths from 8 to 18 μm. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ∼670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ∼660 nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.

  20. 7 CFR 51.2656 - Diameter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the blossom end of the cherry....

  1. Chromosomes without a 30-nm chromatin fiber

    PubMed Central

    Joti, Yasumasa; Hikima, Takaaki; Nishino, Yoshinori; Kamada, Fukumi; Hihara, Saera; Takata, Hideaki; Ishikawa, Tetsuya; Maeshima, Kazuhiro

    2012-01-01

    How is a long strand of genomic DNA packaged into a mitotic chromosome or nucleus? The nucleosome fiber (beads-on-a-string), in which DNA is wrapped around core histones, has long been assumed to be folded into a 30-nm chromatin fiber, and a further helically folded larger fiber. However, when frozen hydrated human mitotic cells were observed using cryoelectron microscopy, no higher-order structures that included 30-nm chromatin fibers were found. To investigate the bulk structure of mitotic chromosomes further, we performed small-angle X-ray scattering (SAXS), which can detect periodic structures in noncrystalline materials in solution. The results were striking: no structural feature larger than 11 nm was detected, even at a chromosome-diameter scale (~1 μm). We also found a similar scattering pattern in interphase nuclei of HeLa cells in the range up to ~275 nm. Our findings suggest a common structural feature in interphase and mitotic chromatins: compact and irregular folding of nucleosome fibers occurs without a 30-nm chromatin structure. PMID:22825571

  2. Multi-watt 589nm fiber laser source

    SciTech Connect

    DAWSON, J W; DROBSHOFF, A D; BEACH, R J; MESSERLY, M J; PAYNE, S A; BROWN, A; PENNINGTON, D M; BAMFORD, D J; SHARPE, S J; COOK, D J

    2006-01-19

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichiometric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd{sup 3+} fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the competing 1088nm 4-level laser transition. At 15W, the 938nm laser has an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  3. MWD tool for deep, small diameter boreholes

    SciTech Connect

    Buytaert, J.P.R.; Duckworth, A.

    1992-03-17

    This patent describes an apparatus for measuring a drilling parameters while drilling a borehole in an earth formation, wherein the borehole includes a small diameter deep borehole portion and a large diameter upper borehole portion. It includes small diameter drillstring means for drilling the deep borehole portion; sensor means, disposed within the small diameter drillstring means, for measuring a drilling parameter characteristic of the deep portion of the borehole while drilling the deep portion of the borehole and for providing sensor output signals indicative of the measured parameter; an upper drillstring portion extending between the surface of the formation and the small diameter drillstring means, the upper drillstring portion including a large diameter drillstring portion; data transmission means disposed within the large diameter drillstring portion and responsive to the sensor output.

  4. Growth of laser damage in fused silica: diameter to depth ratio

    SciTech Connect

    Norton, M A; Adams, J J; Carr, C W; Donohue, E E; Feit, M D; Hackel, R P; Hollingsworth, W G; Jarboe, J A; Matthews, M; Rubenchik, A M; Spaeth, M L

    2007-10-29

    Growth of laser initiated damage plays a major role in determining optics lifetime in high power laser systems. Previous measurements have established that the lateral diameter grows exponentially. Knowledge of the growth of the site in the propagation direction is also important, especially so when considering techniques designed to mitigate damage growth, where it is required to reach all the subsurface damage. In this work, we present data on both the diameter and the depth of a growing exit surface damage sites in fused silica. Measured growth rates with both 351 nm illumination and with combined 351 nm and 1054 nm illumination are discussed.

  5. Diameter dependence of the thermal conductivity of InAs nanowires.

    PubMed

    Swinkels, M Y; van Delft, M R; Oliveira, D S; Cavalli, A; Zardo, I; van der Heijden, R W; Bakkers, E P A M

    2015-09-25

    The diameter dependence of the thermal conductivity of InAs nanowires in the range of 40-1500 nm has been measured. We demonstrate a reduction in thermal conductivity of 80% for 40 nm nanowires, opening the way for further design strategies for nanoscaled thermoelectric materials. Furthermore, we investigate the effect of thermal contact in the most common measurement method for nanoscale thermal conductivity. Our study allows for the determination of the thermal contact using existing measurement setups. The thermal contact resistance is found to be comparable to the wire thermal resistance for wires with a diameter of 90 nm and higher. PMID:26329133

  6. Diameter Dependent Thermoelectric Properties of Individual SnTe Nanowires

    NASA Astrophysics Data System (ADS)

    Xu, E. Z.; Li, Z.; Martinez, J.; Sinitsyn, N.; Htoon, H.; Li, N.; Swartzentruber, B.; Hollingsworth, J.; Wang, J.; Zhang, S. X.

    2015-03-01

    Tin telluride (SnTe), a newly discovered topological crystalline insulator, has recently been suggested to be a promising thermoelectric material. In this work, we report on a systematic study of the thermoelectric properties of individual single-crystalline SnTe nanowires with different diameters. Measurements of thermopower, electrical conductivity and thermal conductivity were carried out on the same nanowires over a temperature range of 25 - 300 K. While the electrical conductivity does not show a strong diameter dependence, we found that the thermopower increases by a factor of two when the nanowire diameter is decreased from 913 nm to 218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may be attributed to the enhanced phonon - surface boundary scattering and phonon-defect scattering. We further calculated the temperature dependent figure of merit ZT for each individual nanowire. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-AC04-94AL85000). We acknowledge support by the Los Alamos LDRD program.

  7. Slip Flow through Colloidal Crystals of Varying Particle Diameter

    PubMed Central

    Rogers, Benjamin J.; Wirth, Mary J.

    2012-01-01

    Slip flow of water through silica colloidal crystals was investigated experimentally for 8 different particle diameters, which have hydraulic channel radii ranging from 15 nm to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 1010 Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63±3 nm. A flow enhancement of 20±2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high volume flow rates. PMID:23237590

  8. Large Diameter Shuttle Launched-AEM (LDSL-AEM) study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A technical description of a Large Diameter Shuttle Launched-AEM (LDSL-AEM), an AEM base module adapted to carry 5 ft diameter payloads in the shuttle with propulsion for carrying payloads to higher altitude orbits from a 150 NM shuttle orbit, is described. The AEM is designed for launch on the scout launch vehicle. Onboard equipment provides capability to despin, acquire the earth, and control the vehicle in an earth pointing mode using reaction wheels for torque with magnets for all attitude acquisition, wheel desaturation, and nutation damping. Earth sensors in the wheels provide pitch and roll attitude. This system provides autonomous control capability to 1 degree in pitch and roll and 2 degrees in yaw. The attitude can be determined to .5 degrees in pitch and roll and 2 degrees in yaw.

  9. Graft Diameter matters in Hamstring ACL reconstruction

    PubMed Central

    Clatworthy, Mark

    2016-01-01

    Objective: Recently techniques have been developed to increase graft diameter in hamstring ACL reconstruction with the hope to decrease graft failure. To date there is limited evidence to show that a smaller graft diameter results in a higher ACL failure rate. Method: The factors for failure in 1480 consecutive single surgeon hamstring ACL reconstructions were evaluated prospectively. Patients were followed for 2-15 years. A multivariate analysis was performed which looked at graft size, age, sex, time to surgery, meniscal integrity, meniscal repair and ACL graft placement to determine whether graft diameter matters in determining the failure of hamstring ACL reconstruction. Results: Graft diameters ranged from 6-10 mm. The mean graft diameter for all patients was 7.75 mm. 83 ACL reconstructions failed. The mean size of graft failures was 7.55 mm ACL reconstructions that failed had a significantly smaller hamstring graft diameter p=0.001. The Hazard Ratio for a smaller diameter graft is 0.517 p=<0.0001. For every 1 mm decrease in graft diameter there is a 48.3% higher chance of failure. The multivariate analysis showed a hazard ratio of 0.543 p=0.002. For every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure. Conclusion: Smaller diameter hamstring grafts do have a higher failure rate. Grafts ≤ 7.5 mm had twice the failure rate of grafts ≥8 mm using a multivariate analysis for every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure.

  10. Temperature characteristic of 808nm VCSELs with large aperture

    NASA Astrophysics Data System (ADS)

    Feng, Yuan; Feng, Dawei; Hao, Yongqin; Wang, Yong; Yan, Changling; Lu, Peng; Li, Yang

    2015-03-01

    In order to study the output characteristics of 808nm vertical cavity surface emitting laser(VCSEL) with large aperture at different temperature, 808nm VCSEL with 500μm emitting diameter are fabricated with Reticular Electrode Structure(RES). Lasing wavelength, optical power and the threshold current are measured by changing the temperature of heat sink. And an output power of 0.42W is achieved at 1.3A at room temperature under continuous wave operation. The central wavelength is 803.32nm, and the full width at half maximum is 0.16nm, the temperature shift is 0.06nm/°, the thermal resistance is 0.098°/mW. The testing results show that 808nm VCSEL with large aperture is good temperature characteristic.

  11. Shrinking plastic tubing and nonstandard diameters

    NASA Technical Reports Server (NTRS)

    Ruiz, W. V.; Thatcher, C. S.

    1980-01-01

    Process allows larger-than-normal postshrink diameters without splitting. Tetrafluoroethylene tubing on mandrel is supported within hot steel pipe by several small diameter coil sections. Rising temperature of mandrel is measured via thermocouple so assembly can be removed without overshrinking (and splitting) of tubing.

  12. Selective Synthesis of Subnanometer Diameter Semiconducting Single-Walled Carbon Nanotubes

    SciTech Connect

    Loebick, C.; Podila, R; Reppert, J; Chudow, J; Ren, F; Haller, G; Rao, A; Pfefferle, L

    2010-01-01

    Subnanometer single-walled carbon nanotubes (sub-nm SWNTs) were synthesized at different temperatures (600, 700, and 800 C) using CoMn bimetallic catalysts supported on MCM-41 silica templates. The state of the catalyst was investigated using X-ray absorption, and the (n,m) indices of the sub-nm SWNTs were determined from Raman spectroscopy and photoluminescence measurements. We find that the size of the metallic particles that seed the growth of sub-nm SWNTs (diameter {approx}0.5-1.0 nm) is highly sensitive to the reaction temperature. Low reaction temperature (600 C) favors the growth of semiconducting tubes whose diameters range from 0.5 to 0.7 nm. These results were also confirmed by electrical transport measurements. Interestingly, dominant intermediate frequency modes on the same intensity scale as the Raman breathing modes were observed. An unusual 'S-like' dispersion of the G-band was present in the Raman spectra of sub-nm SWNTs with diameters <0.7 nm.

  13. Longitudinal Lorentz force on a subwavelength-diameter optical fiber

    SciTech Connect

    Yu Huakang; Fang Wei; Gu Fuxing; Yang Zongyin; Tong Limin; Qiu Min

    2011-05-15

    We analyze the longitudinal Lorentz forces that a propagating continuous-wave light exerts on a subwavelength-diameter optical fiber. Our theoretical results show that, during the propagating process, the guided light exerts no net time-averaged force on the fiber. Via numerical simulation, we find a significant overall pull force of 0.4 pN/mW acting on a 450-nm-diam fiber tip at a wavelength of 980 nm due to the scattering of the end face and a calculated force distribution reveals the feature of a near-field accumulation. Our results may be helpful to the configuration of optomechanical components or devices based on these fibers.

  14. Biofilm formation on a TiO₂ nanotube with controlled pore diameter and surface wettability.

    PubMed

    Anitha, V C; Lee, Jin-Hyung; Lee, Jintae; Banerjee, Arghya Narayan; Joo, Sang Woo; Min, Bong Ki

    2015-02-13

    Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ∼17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells. PMID:25604920

  15. Biofilm formation on a TiO2 nanotube with controlled pore diameter and surface wettability

    NASA Astrophysics Data System (ADS)

    Anitha, V. C.; Lee, Jin-Hyung; Lee, Jintae; Narayan Banerjee, Arghya; Joo, Sang Woo; Min, Bong Ki

    2015-02-01

    Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ˜17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells.

  16. Microbes make average 2 nanometer diameter crystalline UO2 particles.

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.; Kelly, S. D.; Kemner, K. M.; Banfield, J. F.

    2001-12-01

    It is well known that phylogenetically diverse groups of microorganisms are capable of catalyzing the reduction of highly soluble U(VI) to highly insoluble U(IV), which rapidly precipitates as uraninite (UO2). Because biological uraninite is highly insoluble, microbial uranyl reduction is being intensively studied as the basis for a cost-effective in-situ bioremediation strategy. Previous studies have described UO2 biomineralization products as amorphous or poorly crystalline. The objective of this study is to characterize the nanocrystalline uraninite in detail in order to determine the particle size, crystallinity, and size-related structural characteristics, and to examine the implications of these for reoxidation and transport. In this study, we obtained U-contaminated sediment and water from an inactive U mine and incubated them anaerobically with nutrients to stimulate reductive precipitation of UO2 by indigenous anaerobic bacteria, mainly Gram-positive spore-forming Desulfosporosinus and Clostridium spp. as revealed by RNA-based phylogenetic analysis. Desulfosporosinus sp. was isolated from the sediment and UO2 was precipitated by this isolate from a simple solution that contains only U and electron donors. We characterized UO2 formed in both of the experiments by high resolution-TEM (HRTEM) and X-ray absorption fine structure analysis (XAFS). The results from HRTEM showed that both the pure and the mixed cultures of microorganisms precipitated around 1.5 - 3 nm crystalline UO2 particles. Some particles as small as around 1 nm could be imaged. Rare particles around 10 nm in diameter were also present. Particles adhere to cells and form colloidal aggregates with low fractal dimension. In some cases, coarsening by oriented attachment on \\{111\\} is evident. Our preliminary results from XAFS for the incubated U-contaminated sample also indicated an average diameter of UO2 of 2 nm. In nanoparticles, the U-U distance obtained by XAFS was 0.373 nm, 0.012 nm

  17. Slip flow through colloidal crystals of varying particle diameter.

    PubMed

    Rogers, Benjamin J; Wirth, Mary J

    2013-01-22

    Slip flow of water through silica colloidal crystals was investigated experimentally for eight different particle diameters, which have hydraulic channel radii ranging from 15 to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 10(10) Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63 ± 3 nm. A flow enhancement of 20 ± 2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high-volume flow rates. PMID:23237590

  18. Measurement of shaft diameters by machine vision.

    PubMed

    Wei, Guang; Tan, Qingchang

    2011-07-01

    A machine vision method for accurately measuring the diameters of cylindrical shafts is presented. Perspective projection and the geometrical features of cylindrical shafts are modeled in order to enable accurate measurement of shaft diameters. Some of the model parameters are determined using a shaft of known diameter. The camera model itself includes radial and tangential distortions terms. Experiments were used to measure the accuracy of the proposed method and the effect of the position of the camera relative to the shaft, as well as other factors. PMID:21743525

  19. Nanobumps on silicon created with polystyrene spheres and 248 or 308 nm laser pulses

    SciTech Connect

    Piparia, Reema; Rothe, Erhard W.; Baird, R. J.

    2006-11-27

    Huang et al. [Appl. Phys. Lett. 86, 161911 (2005)] formed arrays of nanobumps on a silicon substrate. They applied a 248 nm laser pulse to a surface monolayer of 1-{mu}m-diameter polystyrene spheres. The authors first replicated their experiment with 248 nm light. But when 308 nm pulses were applied instead, the nanobumps had a different shape and composition. At 248 nm, much of the laser light is absorbed in the polystyrene, which serves to quickly distort, melt, and ablate the sphere. At 308 nm, very little light is absorbed. The nanobumps from 248 nm radiation are organic polymers, while those formed with 308 nm pulses are silicon based.

  20. Comparison of 980-nm and 1070-nm in endovenous laser treatment (EVLT)

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Tabakoglu, Ozgur; Ergenoglu, Mehmet U.; Gülsoy, Murat

    2009-07-01

    The use of endovenous laser treatment for varicose veins has been increasing in recent years. It is a safer technique than surgical vein stripping. Its complications (e.g. bruising, pain) are less than the complications of surgical vein stripping. But best parameters such as optimum wavelength, power, and application duration are still under investigation to clarify uncertainties about this technique. To prevent its complications and improve its clinical outcomes, the exact mechanism of it has to be known. The aim of this study is to investigate the effect of different laser wavelengths on endovenous laser therapy. In this study 980-nm diode laser and 1070-nm fiber laser were used. Human veins were irradiated with 980-nm and 1070-nm lasers at 8 W and 10 W to find the optimal power and wavelength. After laser application, remarkable shrinkage was observed. Inner and outer diameters of the veins also narrowed for both of the laser types. 10 W of 980-nm laser application led to better shrinkage results.

  1. Growth of nanostructures with controlled diameter

    DOEpatents

    Pfefferle, Lisa; Haller, Gary; Ciuparu, Dragos

    2009-02-03

    Transition metal-substituted MCM-41 framework structures with a high degree of structural order and a narrow pore diameter distribution were reproducibly synthesized by a hydrothermal method using a surfactant and an anti-foaming agent. The pore size and the mesoporous volume depend linearly on the surfactant chain length. The transition metals, such as cobalt, are incorporated substitutionally and highly dispersed in the silica framework. Single wall carbon nanotubes with a narrow diameter distribution that correlates with the pore diameter of the catalytic framework structure were prepared by a Boudouard reaction. Nanostructures with a specified diameter or cross-sectional area can therefore be predictably prepared by selecting a suitable pore size of the framework structure.

  2. Effect of Shock Precompression on the Critical Diameter of Liquid Explosives

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.; Higgins, Andrew J.; Yoshinaka, Akio C.; Zhang, Fan

    2006-07-01

    The critical diameter of both ambient and shock-precompressed liquid nitromethane confined in PVC tubing are measured experimentally. The experiment was conducted for both amine sensitized and neat NM. In the precompression experiments, the explosive is compressed by a strong shock wave generated by a donor explosive and reflected from a high impedance anvil prior to being detonated by a secondary event. The pressures reached in the test sections prior to detonation propagation was approximately 7 and 8 GPa for amine sensitized and neat NM respectively. The results demonstrated a 30% - 65% decrease in the critical diameter for the shock-compressed explosives. This critical diameter decrease is observed despite a significant decrease in the predicted Von Neumann temperature of the detonation in the precompressed explosive. The results are discussed in the context of theoretical predictions based on thermal ignition theory and previous critical diameter measurements.

  3. Variation of the Diameter of the Sun as Measured by the Solar Disk Sextant (SDS)

    NASA Astrophysics Data System (ADS)

    Girard, Terrence; Sofia, S.; Sofia, U. J.; Twigg, L. W.; Heaps, W.; Thuillier, G.

    2014-01-01

    The balloon-borne Solar Disk Sextant (SDS) experiment has measured the angular size of the Sun on seven occasions spanning the years 1992 to 2011. The solar half-diameter -- observed in a 100-nm wide passband centered at 615 nm -- is found to vary over that period by up to 200 mas, while the typical estimated uncertainty of each measure is 20 mas. The diameter variation is not in phase with the solar activity cycle; thus, the measured diameter variation cannot be explained as an observational artifact of surface activity. Other possible instrument-related explanations for the observed variation are considered and found unlikely, leading us to conclude that the variation is real. The SDS and its results are presented here, including the analysis procedure necessary to calibrate the instrument and allow comparison of diameter measures across decades.

  4. Variation of the diameter of the Sun as measured by the Solar Disk Sextant (SDS)

    NASA Astrophysics Data System (ADS)

    Sofia, S.; Girard, T. M.; Sofia, U. J.; Twigg, L.; Heaps, W.; Thuillier, G.

    2013-12-01

    The balloon-borne Solar Disk Sextant (SDS) experiment has measured the angular size of the Sun on seven occasions spanning the years 1992 to 2011. The solar half-diameter - observed in a 100 nm wide passband centred at 615 nm - is found to vary over that period by up to 200 mas, while the typical estimated uncertainty of each measure is 20 mas. The diameter variation is not in phase with the solar activity cycle; thus, the measured diameter variation cannot be explained as an observational artefact of surface activity. Other possible instrument-related explanations for the observed variation are considered but found unlikely, leading us to conclude that the variation is real. The SDS is described here in detail, as is the complete analysis procedure necessary to calibrate the instrument and allow comparison of diameter measures across decades.

  5. Diameter of titanium nanotubes influences anti-bacterial efficacy

    NASA Astrophysics Data System (ADS)

    Ercan, Batur; Taylor, Erik; Alpaslan, Ece; Webster, Thomas J.

    2011-07-01

    Bacterial infection of in-dwelling medical devices is a growing problem that cannot be treated by traditional antibiotics due to the increasing prevalence of antimicrobial resistance and biofilm formation. Here, due to changes in surface parameters, it is proposed that bacterial adhesion can be prevented through nanosurface modifications of the medical device alone. Toward this goal, titanium was created to possess nanotubular surface topographies of highly controlled diameters of 20, 40, 60, or 80 nm, sometimes followed by heat treatment to control chemistry and crystallinity, through a novel anodization process. For the first time it was found that through the control of Ti surface parameters including chemistry, crystallinity, nanotube size, and hydrophilicity, significantly changed responses of both Staphylococcus epidermidis and Staphylococcus aureus (pathogens relevant for orthopaedic and other medical device related infections) were measured. Specifically, heat treatment of 80 nm diameter titanium tubes produced the most robust antimicrobial effect of all surface treatment parameters tested. This study provides the first step toward understanding the surface properties of nano-structured titanium that improve tissue growth (as has been previously observed with nanotubular titanium), while simultaneously reducing infection without the use of pharmaceutical drugs.

  6. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, E.D.; Hooper, F.M.; Reichenbach, M.L.

    1992-08-11

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut. 1 figure.

  7. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, Eldon D.; Hooper, Frederick M.; Reichenbach, Marvin L.

    1992-01-01

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut.

  8. Making Jointless Dual-Diameter Tubes

    NASA Technical Reports Server (NTRS)

    Kirkham, Kathleen E.

    1989-01-01

    Welds between sections having different diameters eliminated. Single tube made with integral tapered transition section between straight sections of different diameters and wall thicknesses. Made from single piece; contains no joints, welded or otherwise. Not prone to such weld defects as voids and need not be inspected for them. Tube fabricated by either of two methods: drawing or reduction. Both methods used to fabricate tubes of 316L corrosion-resistant stainless steel for use as heat-exchanger coil.

  9. First size-dependent growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei

    NASA Astrophysics Data System (ADS)

    Kuang, C.; Chen, M.; Zhao, J.; Smith, J.; McMurry, P. H.; Wang, J.

    2011-09-01

    This study presents the first measurements of size-dependent particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Data analysis methods were developed, de-coupling the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated particles were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the detector. Size and time-dependent growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, ranging, for example, from 5.6 ± 2.0 to 27 ± 5.3 nm h-1 in Boulder (13:00) and from 5.5 ± 0.82 to 7.6 ± 0.56 nm h-1 in Atlanta (13:00). The resulting growth rate enhancement Γ, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, having lower limit values that approached ~1 at 1.2 nm geometric diameter in Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and having upper limit values that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Survival probability calculations comparing constant and size-dependent growth indicate that neglecting the strong growth rate size dependence from 1 to 3 nm observed in this study could lead to a significant overestimation of CCN survival probability.

  10. Ultra-efficient Engine Diameter Study

    NASA Technical Reports Server (NTRS)

    Daggett, David L.; Brown, Stephen T.; Kawai, Ron T.

    2003-01-01

    Engine fan diameter and Bypass Ratio (BPR) optimization studies have been conducted since the beginning of the turbofan age with the recognition that reducing the engine core jet velocity and increasing fan mass flow rate generally increases propulsive efficiency. However, performance tradeoffs limit the amount of fan flow achievable without reducing airplane efficiency. This study identifies the optimum engine fan diameter and BPR, given the advanced Ultra-Efficient Engine Technology (UEET) powerplant efficiencies, for use on an advanced subsonic airframe. Engine diameter studies have historically focused on specific engine size options, and were limited by existing technology and transportation infrastructure (e.g., ability to fit bare engines through aircraft doors and into cargo holds). This study is unique in defining the optimum fan diameter and drivers for future 2015 (UEET) powerplants while not limiting engine fan diameter by external constraints. This report follows on to a study identifying the system integration issues of UEET engines. This Engine Diameter study was managed by Boeing Phantom Works, Seattle, Washington through the NASA Glenn Revolutionary Aero Space Engine Research (RASER) contract under task order 10. Boeing Phantom Works, Huntington Beach, completed the engine/airplane sizing optimization, while the Boeing Commercial Airplane group (BCA) provided design oversight. A separate subcontract to support the overall project was issued to Tuskegee University.

  11. Measurement of 100 nm and 60 nm Particle Standards by Differential Mobility Analysis

    PubMed Central

    Mulholland, George W.; Donnelly, Michelle K.; Hagwood, Charles R.; Kukuck, Scott R.; Hackley, Vincent A.; Pui, David Y. H.

    2006-01-01

    The peak particle size and expanded uncertainties (95 % confidence interval) for two new particle calibration standards are measured as 101.8 nm ± 1.1 nm and 60.39 nm ± 0.63 nm. The particle samples are polystyrene spheres suspended in filtered, deionized water at a mass fraction of about 0.5 %. The size distribution measurements of aerosolized particles are made using a differential mobility analyzer (DMA) system calibrated using SRM® 1963 (100.7 nm polystyrene spheres). An electrospray aerosol generator was used for generating the 60 nm aerosol to almost eliminate the generation of multiply charged dimers and trimers and to minimize the effect of non-volatile contaminants increasing the particle size. The testing for the homogeneity of the samples and for the presence of multimers using dynamic light scattering is described. The use of the transfer function integral in the calibration of the DMA is shown to reduce the uncertainty in the measurement of the peak particle size compared to the approach based on the peak in the concentration vs. voltage distribution. A modified aerosol/sheath inlet, recirculating sheath flow, a high ratio of sheath flow to the aerosol flow, and accurate pressure, temperature, and voltage measurements have increased the resolution and accuracy of the measurements. A significant consideration in the uncertainty analysis was the correlation between the slip correction of the calibration particle and the measured particle. Including the correlation reduced the expanded uncertainty from approximately 1.8 % of the particle size to about 1.0 %. The effect of non-volatile contaminants in the polystyrene suspensions on the peak particle size and the uncertainty in the size is determined. The full size distributions for both the 60 nm and 100 nm spheres are tabulated and selected mean sizes including the number mean diameter and the dynamic light scattering mean diameter are computed. The use of these particles for calibrating DMAs and for

  12. Optical diameters of stars measured with the Mt. Wilson Mark III interferometer

    NASA Technical Reports Server (NTRS)

    Simon, R. S.; Mozurkewich, D.; Johnston, K. J.; Gaume, Ralph; Hutter, D. J.; Bowers, P. F.; Colavita, M. M.; Shao, M.

    1990-01-01

    Reliable stellar angular diameters can now be determined using the Mark III Optical Interferometer located on Mt. Wilson, California. The Mark III is a Michelson Interferometer capable of measuring the interferometric fringe visibility for stars using interferometer baselines varying from 3 to 31.5 meters in length. Angular diameters measured with the Mark III Optical Interferometer are presented for 12 stars at wavelengths of 450 and 800 nm.

  13. Diameter distribution of thermally evaporated indium metal islands on silicon substrates

    NASA Astrophysics Data System (ADS)

    Balch, Joleyn; Tsakalakos, Loucas; Huber, William; Grande, James; Knussman, Michael; Cale, Timothy S.

    2007-09-01

    Although many groups have studied the initial growth stages of various metals, including indium, there is little information in literature on diameter distributions of indium in relation to film thickness or annealing conditions. This paper reports island size distributions of thermally evaporated In islands on Si (100) and Si (111) substrates for nominal film thicknesses ranging from 5 to 50 nm. Because indium has a low melting temperature, and therefore a high homologous temperature at room temperature, 3-dimensional islands form during deposition with no subsequent heat treatments needed. Island diameters were calculated using commercial image analysis software in conjunction with SEM images of the samples. It is found that there is a bimodal island diameter distribution for nominal indium thicknesses greater than 5 nm. While the diameters of the larger islands increase exponentially with nominal thickness, those of the smaller islands increase linearly, and therefore more slowly, with nominal thickness. For nominal thickness of 50 nm, the average diameters of the small and large islands differ by almost an order of magnitude. Anneal conditions were studied in an attempt to narrow diameter distributions. Samples of each nominal thickness were annealed at temperatures ranging from 360°C to 550°C and the diameters again measured. The range of island diameters become narrower with 360°C anneal and volume average island diameter increases by ~30-50%. This narrowing of the distribution occurs due to smaller islands being absorbed by the larger in a process akin to Ostwald ripening, which is facilitated by higher surface diffusivities at higher homologous temperatures.

  14. DiameterJ: A validated open source nanofiber diameter measurement tool.

    PubMed

    Hotaling, Nathan A; Bharti, Kapil; Kriel, Haydn; Simon, Carl G

    2015-08-01

    Despite the growing use of nanofiber scaffolds for tissue engineering applications, there is not a validated, readily available, free solution for rapid, automated analysis of nanofiber diameter from scanning electron microscope (SEM) micrographs. Thus, the goal of this study was to create a user friendly ImageJ/FIJI plugin that would analyze SEM micrographs of nanofibers to determine nanofiber diameter on a desktop computer within 60 s. Additional design goals included 1) compatibility with a variety of existing segmentation algorithms, and 2) an open source code to enable further improvement of the plugin. Using existing algorithms for centerline determination, Euclidean distance transforms and a novel pixel transformation technique, a plugin called "DiameterJ" was created for ImageJ/FIJI. The plugin was validated using 1) digital synthetic images of white lines on a black background and 2) SEM images of nominally monodispersed steel wires of known diameters. DiameterJ analyzed SEM micrographs in 20 s, produced diameters not statistically different from known values, was over 10-times closer to known diameter values than other open source software, provided hundreds of times the sampling of manual measurement, and was hundreds of times faster than manual assessment of nanofiber diameter. DiameterJ enables users to rapidly and thoroughly determine the structural features of nanofiber scaffolds and could potentially allow new insights to be formed into fiber diameter distribution and cell response. PMID:26043061

  15. Ultrahigh-resolution and non-contact diameter measurement of metallic wire using eddy current sensor.

    PubMed

    Li, Wei; Wang, Hongbo; Feng, Zhihua

    2014-08-01

    This paper proposes a new method using eddy current sensor (ECS) for online non-contact diameter measurement of metallic wires with ultrahigh resolution. A prototype sensor was designed, fabricated, and tested for copper wires with diameters ranging from 1.12 mm to 1.30 mm. A solenoid coil with dimensions of 16 mm long and 2.1 mm in diameter is used as sensing element with a working frequency of 1.3 MHz. With a well-designed bridge, the sensing coil's inductance variation can be detected and the wire's diameter can be calculated. The ECS system demonstrated a dynamic resolution better than 2.2 μm and a static resolution better than 0.42 nm for a wire with a diameter of 1.3 mm. This non-contact method has competitive advantages over other methods in many aspects, especially in terms of measurement resolution. PMID:25173300

  16. MreB Orientation Correlates with Cell Diameter in Escherichia coli.

    PubMed

    Ouzounov, Nikolay; Nguyen, Jeffrey P; Bratton, Benjamin P; Jacobowitz, David; Gitai, Zemer; Shaevitz, Joshua W

    2016-09-01

    Bacteria have remarkably robust cell shape control mechanisms. For example, cell diameter only varies by a few percent across a given population. The bacterial actin homolog, MreB, is necessary for establishment and maintenance of rod shape although the detailed properties of MreB that are important for shape control remained unknown. In this study, we perturb MreB in two ways: by treating cells with the polymerization-inhibiting drug A22 and by creating point mutants in mreB. These perturbations modify the steady-state diameter of cells over a wide range, from 790 ± 30 nm to 1700 ± 20 nm. To determine which properties of MreB are important for diameter control, we correlated structural characteristics of fluorescently tagged MreB polymers with cell diameter by simultaneously analyzing three-dimensional images of MreB and cell shape. Our results indicate that the helical pitch angle of MreB inversely correlates with the cell diameter of Escherichia coli. Other correlations between MreB and cell diameter are not found to be significant. These results demonstrate that the physical properties of MreB filaments are important for shape control and support a model in which MreB organizes the cell wall growth machinery to produce a chiral cell wall structure and dictate cell diameter. PMID:27602731

  17. Large diameter astromast development, phase 1

    NASA Technical Reports Server (NTRS)

    Preiswerk, P. R.; Finley, L. A.; Knapp, K.

    1983-01-01

    Coilable-longeron lattice columns called Astromasts (trademark) were manufactured for a variety of spacecraft missions. These flight structures varied in diameter from 0.2 to 0.5 meter (9 to 19 in.), and the longest Astromast of this type deploys to a length of 30 meters (100 feet). A double-laced diagonal Astromast design referred to as the Supermast (trademark) which, because it has shorter baylengths than an Astromast, is approximately four times as strong. The longeron cross section and composite material selection for these structures are limited by the maximum strain associated with stowage and deployment. As a result, future requirements for deployable columns with high stiffness and strength require the development of both structures in larger diameters. The design, development, and manufacture of a 6.1-m-long (20-ft), 0.75-m-diameter (30-in.), double-laced diagonal version of the Astromast is described.

  18. Videodensitometry for measuring blood vessel diameter.

    PubMed

    Hoornstra, K; Hanselman, J M; Holland, W P; De Wey Peters, G W; Zwamborn, A W

    1980-01-01

    A method employing a special computer for determining the internal diameters of blood vessels from photofluorographic image is described; in vitro and in vivo experiments are performed with the system. The amount of contrast medium injected is restricted to 4 times 3 ml, and it is possible to determine the diameter (in the range from 2 to 16 mm) at any place where blood vessels can be catheterized. In the in vivo experiments the maximum systematic error is +/-5 percent in the 7 to 8 mm range. PMID:7424549

  19. THERMAL EVALUATION OF DIFFERENT DRIFT DIAMETER SIZES

    SciTech Connect

    H.M. Wade

    1999-01-04

    The purpose of this calculation is to estimate the thermal response of a repository-emplaced waste package and its corresponding drift wall surface temperature with different drift diameters. The case examined is that of a 21 pressurized water reactor (PWR) uncanistered fuel (UCF) waste package loaded with design basis spent nuclear fuel assemblies. This calculation evaluates a 3.5 meter to 6.5 meter drift diameter range in increments of 1.0 meters. The time-dependent temperatures of interest, as determined by this calculation, are the spent nuclear fuel cladding temperature, the waste package surface temperature, and the drift wall surface temperature.

  20. Shaft Diameter Measurement Using Structured Light Vision

    PubMed Central

    Liu, Siyuan; Tan, Qingchang; Zhang, Yachao

    2015-01-01

    A method for measuring shaft diameters is presented using structured light vision measurement. After calibrating a model of the structured light measurement, a virtual plane is established perpendicular to the measured shaft axis and the image of the light stripe on the shaft is projected to the virtual plane. On the virtual plane, the center of the measured shaft is determined by fitting the projected image under the geometrical constraints of the light stripe, and the shaft diameter is measured by the determined center and the projected image. Experiments evaluated the measuring accuracy of the method and the effects of some factors on the measurement are analyzed. PMID:26274963

  1. 1064-nm Nd:YAG laser nucleotomy

    NASA Astrophysics Data System (ADS)

    Vari, Sandor G.; Pergadia, Vani R.; Shi, Wei-Qiang; Snyder, Wendy J.; Fishbein, Michael C.; Grundfest, Warren S.

    1993-07-01

    The high incidence of patients with clinical and neurological symptoms of lumbar disc herniation has spurred the development of less invasive and more cost efficient methods to treat patients. In this study we evaluated pulsed and continuous wave (cw) 1064 nm Nd:YAG laser ablation and induced thermal damage in sheep intervertebral disc. We used the Heraeus LaserSonics Hercules 5040 (Nd:YAG) laser system and 400 micrometers bare and 600 micrometers ball-tipped fibers in cw and pulsed mode. For the laser parameters and fibers used in this study, ablation of the intervertebral disc was successful and thermal damage did not exceed 0.5 mm. Varying beam diameters and focusing abilities (i.e., bare and ball) did not produce any difference in the coagulation thermal effect.

  2. Changing the Diameter of a Viewing Tube

    ERIC Educational Resources Information Center

    Obara, Samuel

    2009-01-01

    This article is about the students' investigation about the relationship between the diameter of the view tubes (x) of constant lengths and the viewable vertical distance (y) on the wall while keeping the perpendicular distance from the eyeball to the wall constant. The students collected data and used and represented it in tabular and graphical…

  3. Small diameter symmetric networks from linear groups

    NASA Technical Reports Server (NTRS)

    Campbell, Lowell; Carlsson, Gunnar E.; Dinneen, Michael J.; Faber, Vance; Fellows, Michael R.; Langston, Michael A.; Moore, James W.; Multihaupt, Andrew P.; Sexton, Harlan B.

    1992-01-01

    In this note is reported a collection of constructions of symmetric networks that provide the largest known values for the number of nodes that can be placed in a network of a given degree and diameter. Some of the constructions are in the range of current potential engineering significance. The constructions are Cayley graphs of linear groups obtained by experimental computation.

  4. Reducing the diameters of computer networks

    NASA Technical Reports Server (NTRS)

    Bokhari, S. H.; Raza, A. D.

    1986-01-01

    Three methods of reducing the diameters of computer networks by adding additional processor to processor links under the constraint that no more than one I/O port be added to each processor are discussed. This is equivalent to adding edges to a given graph under the constraint that the degree of any node be increased, at most, by one.

  5. Computing Minimum Diameter Color-Spanning Sets

    NASA Astrophysics Data System (ADS)

    Fleischer, Rudolf; Xu, Xiaoming

    We study the minimum diameter color-spanning set problem which has recently drawn some attention in the database community. We show that the problem can be solved in polynomial time for L 1 and L ∞ metrics, while it is NP-hard for all other L p metrics even in two dimensions. However, we can efficiently compute a constant factor approximation.

  6. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to a line from stem to blossom end. When measuring for maximum size, “diameter” means the smallest dimension of the apple determined...

  7. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to... dimension of the apple determined by passing the apple through a round opening in any position....

  8. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to... dimension of the apple determined by passing the apple through a round opening in any position....

  9. Synchronized ps fiber lasers with pulse durations (25, 50, 100-2000ps) and repetition rates (100kHz-150Mhz) continuously tunable over three orders of magnitude

    NASA Astrophysics Data System (ADS)

    Dupuis, Alexandre; Burgoyne, Bryan; Pena, Guido; Archambault, André; Lemieux, Dominic; Solomonean, Vasile; Duong, Maxime; Villeneuve, Alain

    2013-03-01

    Ultrafast lasers are enabling precision machining of a wide variety of materials. However, the optimal laser parameters for proper material processing can differ greatly from one material to another. In order to cut high aspect-ratio features at high processing speeds the laser parameters such as pulse energy, repetition rate, and cutting speed need to be optimized. In particular, a shorter pulse duration plays an important role in reducing the thermal damage in the Heat-Affected Zones. In this paper we present a novel ps fiber laser whose electronically tunable parameters aim to facilitate the search for optimal processing parameters. The 20W 1064nm Yb fiber laser is based on a Master Oscillator Power Amplifier (MOPA) architecture with a repetition rate that can be tuned continuously from 120kHz to 120MHz. More importantly, the integration of three different pulse generators enables the pulse duration to be switched from 25ps to 50ps, or to any value within the 55ps to 2000ps range. By reducing the pulse duration from the ns-regime down to 25ps, the laser approaches the transition from the thermal processing regime to the ablation regime of most materials. Moreover, in this paper we demonstrate the synchronization of the pulses from two such MOPA lasers. This enables more elaborate multipulse processing schemes where the pulses of each laser can be set to different parameter values, such as an initial etching pulse followed by a thermal annealing pulse. It should be noted that all the laser parameters are controlled electronically with no moving parts, including the synchronization.

  10. Switching Properties of sub-100 nm Perpendicular Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Tryputen, Larysa; Piotrowski, Stephan; Bapna, Mukund; Chien, Chia-Ling; Wang, Weigang; Majetich, Sara; Ross, Caroline

    2015-03-01

    Perpendicular magnetic tunnel junctions (p-MTJs) have great potential for realizing high-density non-volatile memory and logic devices. It is critical to solve scalability problem to implement such devices, to achieve low resistance area and to reduce switching current density while maintaining thermal stability. We present our recent results on fabrication of high resolution Ta/CoFeB/MgO/CoFeB/Ta p-MTJ devices and characterization of their switching properties as well as topography and current mapping by using nanoscale Conductive Atomic Force Microscopy. Our patterning method is based on using hydrogen silsesquioxane resist mask combined with ion beam etching. It allows to fabricate p-MTJ devices down to 40 nm in diameter while maintaining the magnetic quality of the multilayers. Repeatable, consistent switching behaviour has been observed in the obtained p-MTJ devices of 500 nm down to 40 nm with 10 - 800 mV voltage applied. Switching field increased as device diameter decreased, from 580 Oe at 500 nm (MR = 10%) to 410 Oe at 80 nm (MR = 9%). We discuss the effect of device sizes on the switching properties. This work was supported in part by C-SPIN, one of the six centers of STARnet, a Semiconductor Research Corporation Program sponsored by MARCO and DARPA and in part through the National Science Foundation through NCN-Needs Program, Contract 12207020-EEC.

  11. Influence of diesel engine combustion parameters on primary soot particle diameter.

    PubMed

    Mathis, Urs; Mohr, Martin; Kaegi, Ralf; Bertola, Andrea; Boulouchos, Konstantinos

    2005-03-15

    Effects of engine operating parameters and fuel composition on both primary soot particle diameter and particle number size distribution in the exhaust of a direct-injected heavy-duty diesel engine were studied in detail. An electrostatic sampler was developed to deposit particles directly on transmission electron microscopy (TEM) grids. Using TEM, the projected area equivalent diameter of primary soot particles was determined. A scanning mobility particle sizer (SMPS) was used for the measurement of the particle number size distribution. Variations in the main engine operating parameters (fuel injection system, air management, and fuel properties) were made to investigate soot formation and oxidation processes. Primary soot particle diameters determined by TEM measurements ranged from 17.5 to 32.5 nm for the diesel fuel and from 24.1 to 27.2 nm for the water-diesel emulsion fuel depending on the engine settings. For constant fuel energy flow rate, the primary particle size from the water-diesel emulsion fuel was slightly larger than that from the diesel fuel. A reduction in primary soot particle diameter was registered when increasing the fuel injection pressure (IP) or advancing the start of injection (SOI). Larger primary soot particle diameters were measured while the engine was operating with exhaust gas recirculation (EGR). Heat release rate analysis of the combustion process revealed that the primary soot particle diameter decreased when the maximum flame temperature increased for the diesel fuel. PMID:15819252

  12. Diameter Dependence of Planar Defects in InP Nanowires.

    PubMed

    Wang, Fengyun; Wang, Chao; Wang, Yiqian; Zhang, Minghuan; Han, Zhenlian; Yip, SenPo; Shen, Lifan; Han, Ning; Pun, Edwin Y B; Ho, Johnny C

    2016-01-01

    In this work, extensive characterization and complementary theoretical analysis have been carried out on Au-catalyzed InP nanowires in order to understand the planar defect formation as a function of nanowire diameter. From the detailed transmission electron microscopic measurements, the density of stacking faults and twin defects are found to monotonically decrease as the nanowire diameter is decreased to 10 nm, and the chemical analysis clearly indicates the drastic impact of In catalytic supersaturation in Au nanoparticles on the minimized planar defect formation in miniaturized nanowires. Specifically, during the chemical vapor deposition of InP nanowires, a significant amount of planar defects is created when the catalyst seed sizes are increased with the lower degree of In supersaturation as dictated by the Gibbs-Thomson effect, and an insufficient In diffusion (or Au-rich enhancement) would lead to a reduced and non-uniform In precipitation at the NW growing interface. The results presented here provide an insight into the fabrication of "bottom-up" InP NWs with minimized defect concentration which are suitable for various device applications. PMID:27616584

  13. Coke from small-diameter tubes analyzed

    SciTech Connect

    Albright, L.F.

    1988-08-29

    The mechanism for coke deposit formation and the nature of the coke itself can vary with the design of the ethylene furnace tube bank. In this article, coke deposits from furnaces with small-diameter pyrolysis tubes are examined. The samples were taken from four furnaces of identical design (Plant B). As in both the first and second installments of the series, the coke deposits were examined using a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDAX). The deposits from the small-diameter tubes are compared with the coke deposits from the furnace discussed in earlier articles. Analysis of the coke in both sets of samples are then used to offer recommendations for improved decoking procedures, operating procedures, better feed selection, and better selection of the metallurgy used in furnace tubes, to extend the operating time of the furnace tubes by reducing the amount and type of coke build up.

  14. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, David E.; Petrini, Richard R.; Carter, Gary W.

    1981-01-01

    An improved rod optic system for inspecting small diameter, deep bores. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90.degree. to minimize optical distortion in examining the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable of examining 1/16 inch diameter and up to 4 inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and right angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  15. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, D.E.; Petrini, R.R.; Carter, G.W.

    An improved rod optic system for inspecting small diameter, deep bores is described. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90/sup 0/ to minimize optical distortion in examing the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable if examing 1/16 inch diameter and up to 4-inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and righ angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  16. European Projects of Solar Diameter Monitoring

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino; Bianda, Michele; Arnaud, Jean

    2008-10-01

    Three projects dealing with solar diameter evolution are presently in development. Historical and contemporary eclipses and planetary transits data collection and analysis, to cover potentially the last 5 centuries with an accuracy of few hundreds of arcsecond on diameter's measurements. The French space mission PICARD with a few milliarcseconds accuray. With PICARD-SOL instruments located at the plateau of Calern the role of the atmosphere in ground-based measurements will be clarified. CLAVIUS is a Swiss-Italian project based on drift-scan method, free from optical distortions, where hourly circles transits will be monitored with fast CMOS sensors in different wavebands. The will run at IRSOL Gregory-Coudé telescope.

  17. On finding minimum-diameter clique trees

    SciTech Connect

    Blair, J.R.S. . Dept. of Computer Science); Peyton, B.W. )

    1991-08-01

    It is well-known that any chordal graph can be represented as a clique tree (acyclic hypergraph, join tree). Since some chordal graphs have many distinct clique tree representations, it is interesting to consider which one is most desirable under various circumstances. A clique tree of minimum diameter (or height) is sometimes a natural candidate when choosing clique trees to be processed in a parallel computing environment. This paper introduces a linear time algorithm for computing a minimum-diameter clique tree. The new algorithm is an analogue of the natural greedy algorithm for rooting an ordinary tree in order to minimize its height. It has potential application in the development of parallel algorithms for both knowledge-based systems and the solution of sparse linear systems of equations. 31 refs., 7 figs.

  18. Magnetic Behavior of Surface Nanostructured 50-nm Nickel Thin Films

    PubMed Central

    2010-01-01

    Thermally evaporated 50-nm nickel thin films coated on borosilicate glass substrates were nanostructured by excimer laser (0.5 J/cm2, single shot), DC electric field (up to 2 kV/cm) and trench-template assisted technique. Nanoparticle arrays (anisotropic growth features) have been observed to form in the direction of electric field for DC electric field treatment case and ruptured thin film (isotropic growth features) growth for excimer laser treatment case. For trench-template assisted technique; nanowires (70–150 nm diameters) have grown along the length of trench template. Coercive field and saturation magnetization are observed to be strongly dependent on nanostructuring techniques. PMID:21076670

  19. Fabricated nano-fiber diameter as liquid concentration sensors

    NASA Astrophysics Data System (ADS)

    Chyad, Radhi M.; Mat Jafri, Mohd Zubir; Ibrahim, Kamarulazizi

    Nanofiber is characterized by thin, long, and very soft silica. Taper fibers are made using an easy and low cost chemical method. Etching is conducted with a HF solution to remove cladding and then a low molarity HF solution to reduce the fiber core diameter. One approach to on-line monitoring of the etching process uses spectrophotometer with a white light source. In the aforementioned technique, this method aims to determine the diameter of the reduced core and show the evolution of the two different processes from the nanofiber regime to the fixed regime in which the mode was remote from the surrounding evanescent field, intensity can propagate outside the segment fiber when the core diameter is less than 500 nm. Manufacturing technologies of nano-fiber sensors offer a number of approved properties of optical fiber sensors utilized in various sensory applications. The nano-fiber sensor is utilized to sense the difference in the concentration of D-glucose in double-distilled deionized water and to measure the refractive index (RI) of a sugar solution. Our proposed method exhibited satisfactory capability based on bimolecular interactions in the biological system. The response of the nano-fiber sensors indicates a different kind of interaction among various groups of AAs. These results can be interpreted in terms of solute-solute and solute-solvent interactions and the structure making or breaking ability of solutes in the given solution. This study utilized spectra photonics to measure the transmission of light through different concentrations of sugar solution, employing cell cumber and nano-optical fibers as sensors.

  20. Lasing in microdisks of ultrasmall diameter

    SciTech Connect

    Zhukov, A. E. Kryzhanovskaya, N. V.; Maximov, M. V.; Lipovskii, A. A.; Savelyev, A. V.; Bogdanov, A. A.; Shostak, I. I.; Moiseev, E. I.; Karpov, D. V.; Laukkanen, J.; Tommila, J.

    2014-12-15

    It is demonstrated by calculations and experimental results that room-temperature lasing can be obtained at the ground-state optical transition of InAs/InGaAs/GaAs quantum dots in optical microcavities with a record-small diameter of 1.5 μm. In 1-μm cavities, lasing occurs at the wavelength of one of the whispering-gallery modes within the band corresponding to the first excited-state optical transition.

  1. Effect of Anodic Alumina Oxide Pore Diameter on the Crystallization of Poly(butylene adipate).

    PubMed

    Sun, Xiaoli; Fang, Qunqun; Li, Huihui; Ren, Zhongjie; Yan, Shouke

    2016-04-01

    Poly(butylene adipate) (PBA) was infiltrated into the anodic alumina oxide (AAO) templates with the pore diameter of around 30, 70, and 100 nm and PBA nanotubes with different diameters were prepared. The crystallization and phase transition behavior of the obtained PBA nanotubes capped in the nanopores have been explored by using X-ray diffraction and differential scanning calorimetry. Only α-PBA crystals form in the bulk sample during nonisothermal crystallization. By contrast, predominant β-PBA crystals form in the AAO templates. The β-PBA crystals formed in the nanopores with pore diameter less than 70 nm prefer to adopt an orientation with their b-axis parallel to the long axis of the pore. During the melt recrystallization, it was found that the critical temperature (Tβ), below which pure β-crystals form, is 20 °C for bulk PBA. It drops down significantly with the pore diameter for the PBA in the AAO template. Moreover, the β-crystals in the porous template exhibit larger lattice parameters compared with the bulk crystals. By monitoring the change of β-crystals in the heating process, it was found that β-crystals in the AAO template with the pore diameter of 30 nm (D30) melt directly while the β-crystals transform to α-crystals in the template with the pore diameter of 100 nm (D100). The intensity of (020) Bragg peak of β-crystals decreases at a similar rate in both D30 and D100 but disappears at a relatively lower temperature in D30. On the other hand, the β(110) peak intensity of β-PBA crystals formed in the D100 template decreases first at slower rate before α crystals appear, and then at a faster rate once the β to α phase transition takes place. PMID:27008378

  2. Log-normal diameter distribution of Pd-based metallic glass droplet and wire

    PubMed Central

    Yaginuma, S.; Nakajima, C.; Kaneko, N.; Yokoyama, Y.; Nakayama, K. S.

    2015-01-01

    We have studied the formation of Pd42.5Cu30Ni7.5P20 metallic glass droplets and wires in the gas atomization process. We demonstrate that the sizes of droplets and wires can be distinguished by the Ohnesorge number (Oh), which is the proportion of the spinnability to the capillary instability, and the diameter distributions follow a log-normal distribution function, implying cascade fragmentation. For droplets, the number significantly increases at Oh < 1 but the diameter gradually decreases. For wires, the number greatly increases at Oh > 1 while the diameter steadies below 400 nm. Further, the wire diameter is quadrupled at Oh = 16 due to the high viscosity which suppresses both capillary breakup and ligament elongation. PMID:26030090

  3. Considerations for fine hole patterning for the 7nm node

    NASA Astrophysics Data System (ADS)

    Yaegashi, Hidetami; Oyama, Kenichi; Hara, Arisa; Natori, Sakurako; Yamauchi, Shohei; Yamato, Masatoshi; Koike, Kyohei

    2016-03-01

    One of the practical candidates to produce 7nm node logic devices is to use the multiple patterning with 193-immersion exposure. For the multiple patterning, it is important to evaluate the relation between the number of mask layer and the minimum pitch systematically to judge the device manufacturability. Although the number of the time of patterning, namely LE(Litho-Etch) ^ x-time, and overlay steps have to be reduced, there are some challenges in miniaturization of hole size below 20nm. Various process fluctuations on contact hole have a direct impact on device performance. According to the technical trend, 12nm diameter hole on 30nm-pitch hole will be needed on 7nm node. Extreme ultraviolet lithography (EUV) and Directed self-assembly (DSA) are attracting considerable attention to obtain small feature size pattern, however, 193-immersion still has the potential to extend optical lithography cost-effectively for sub-7nm node. The objective of this work is to study the process variation challenges and resolution in post-processing for the CD-bias control to meet sub-20nm diameter contact hole. Another pattern modulation is also demonstrated during post-processing step for hole shrink. With the realization that pattern fidelity and pattern placement management will limit scaling long before devices and interconnects fail to perform intrinsically, the talk will also outline how circle edge roughness (CER) and Local-CD uniformity can correct efficiency. On the other hand, 1D Gridded-Design-Rules layout (1D layout) has simple rectangular shapes. Also, we have demonstrated CD-bias modification on short trench pattern to cut grating line for its fabrication.

  4. Calibration of area based diameter distribution with individual tree based diameter estimates using airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Xu, Qing; Hou, Zhengyang; Maltamo, Matti; Tokola, Timo

    2014-07-01

    Diameter distribution is essential for calculating stem volume and timber assortments of forest stands. A new method was proposed in this study to improve the estimation of stem volume and timber assortments, by means of combining the Area-based approach (ABA) and individual tree detection (ITD), the two main approaches to deriving forest attributes from airborne laser scanning (ALS) data. Two methods, replacement, and histogram matching were employed to calibrate ABA-derived diameter distributions with ITD-derived diameter estimates at plot level. The results showed that more accurate estimates were obtained when calibrations were applied. In view of the highest accuracy between ABA and ITD, calibrated diameter distributions decreased its relative RMSE of the estimated entire growing stock, saw log and pulpwood fractions by 2.81%, 3.05% and 7.73% points at best, respectively. Calibration improved pulpwood fraction significantly, which contributed to the negligible bias of the estimated entire growing stock.

  5. Generation of 30-50 nm structures using easily fabricated, composite PDMS masks.

    PubMed

    Odom, Teri W; Thalladi, Venkat R; Love, J Christopher; Whitesides, George M

    2002-10-16

    This communication demonstrates an approach to generate simple nanostructures with critical dimensions down to 30 nm over cm2-sized areas using composite PDMS masks. These masks were patterned with feature sizes down to 100 nm. When used in phase-shifting lithography, these masks generated arrays of structures in photoresist with line widths as small as 30 nm, slots in metal with features down to 40 nm, and wells in epoxy with diameters as small as 100 nm. The wells were used to prepare arrays of uniformly sized nanocrystals of salts. PMID:12371848

  6. Photoionization of Nitromethane at 355nm and 266nm

    NASA Astrophysics Data System (ADS)

    Martínez, Denhi; Betancourt, Francisco; Poveda, Juan Carlos; Guerrero, Alfonso; Cisneros, Carmen; Álvarez, Ignacio

    2014-05-01

    Nitromethane is one of the high-yield clean liquid fuels, i.e., thanks to the oxygen contained in nitromethane, much less atmospheric oxygen is burned compared to hydrocarbons such as gasoline, making the nitromethane an important prototypical energetic material, the understanding of its chemistry is relevant in other fields such as atmospheric chemistry or biochemistry. In this work we present the study of photoionization dynamics by multiphoton absorption with 355 nm and 266 nm wavelength photons, using time of flight spectrometry in reflectron mode (R-TOF). Some of the observed ion products appear for both wavelength and other only in one of them; both results were compared with preview observations and new ions were detected. This work is supported by CONACYT grant 165410 and DGAPA-UNAM grants IN-107-912 and IN-102-613.

  7. Variable diameter wind turbine rotor blades

    DOEpatents

    Jamieson, Peter McKeich; Hornzee-Jones, Chris; Moroz, Emilian M.; Blakemore, Ralph W.

    2005-12-06

    A system and method for changing wind turbine rotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the wind turbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

  8. Stellar Angular Diameter Relations for Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Adams, Arthur; Boyajian, Tabetha S.; von Braun, Kaspar

    2016-01-01

    Determining the physical properties of microlensing events depends on having accurate angular radii of the source star. Using long-baseline optical interferometry we are able to determine the angular sizes of nearby stars with uncertainties less than 2 percent. We present empirical estimates of angular diameters for both dwarfs/subgiants and giant stars as functions of five color indices which are relevant to planned microlensing surveys. We find in all considered colors that metallicity does not play a statistically significant role in predicting stellar size for the samples of stars considered.

  9. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  10. A Variable Diameter Short Haul Civil Tiltrotor

    NASA Technical Reports Server (NTRS)

    Wang, James M.; Jones, Christopher T.; Nixon, Mark W.

    1999-01-01

    The Short-Haul-Civil-tiltrotor (SHCT) component of the NASA Aviation System Capacity Program is an effort to develop the technologies needed for a potential 40-passenger civil tiltrotor. The variable diameter tiltrotor (VDTR) is a Sikorsky concept aimed at improving tiltrotor hover and cruise performance currently limited by disk loading that is much higher in hover than conventional helicopter, and much lower in cruise than turbo-prop systems. This paper describes the technical merits of using a VDTR on a SHCT aircraft. The focus will be the rotor design.

  11. Thread gauge for measuring thread pitch diameters

    DOEpatents

    Brewster, Albert L.

    1985-01-01

    A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade.

  12. Thread gauge for measuring thread pitch diameters

    DOEpatents

    Brewster, A.L.

    1985-11-19

    A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts is disclosed. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade. 2 figs.

  13. The diameter and albedo of 1943 Anteros

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Tedesco, E. F.; Tholen, D. J.; Tokunaga, A.; Matthews, K.; Neugebauer, G.; Soifer, B. T.; Kowal, C.

    1981-01-01

    The results of broadband visual and infrared photometry of the Apollo-Amor asteroid 1943 Anteros during its 1980 apparition are reported. By means of a radiometric model, a diameter of 2.3 + or - 0.2 km and a visual geometric albedo of 0.13 + or - 0.03 is calculated. The albedo and reflectance spectrum of Anteros imply that it is a type S asteroid. Thus, Anteros may have a silicate surface similar to other Apollo-Amor asteroids as well as some stony-iron meteorites.

  14. Anomalous diameter dependence of thermal transport in ultra-narrow Si nanowires

    SciTech Connect

    Karamitaheri, Hossein; Neophytou, Neophytos; Kosina, Hans

    2014-01-14

    We present atomistic valence force field calculations of thermal transport in Si nanowires of diameters from 12 nm down to 1 nm. We show that as the diameter is reduced, the phonon density-of-states and transmission function acquire a finite value at low frequency, in contrast to approaching zero as in the bulk material. It turns out that this effect results in what Ziman described as the “problem of long longitudinal waves” [J. M. Ziman, Electrons and Phonons: The Theory of Transport Phenomena in Solids (Clarendon, Oxford, 1962)], which states that the thermal conductivity of a material increases as its length is increased due to the vanishing scattering for long-wavelength phonons. We show that this thermal transport improvement also appears in nanowires as their diameter is decreased below D = 5 nm (not only as the length increases), originating from the increase in the density of the long wavevector modes. The observation is present under ballistic transport conditions, and further enhanced with the introduction of phonon-phonon scattering. Because of this, in such ultra-narrow nanowires, as the diameter is reduced, phonon transport is dominated more and more by lower energy phonons with longer mean-free paths. We show that ∼80% of the heat is carried by phonons with energies less than 5 meV, most with mean-free paths of several hundreds of nanometers.

  15. Diameter control of carbon nanotubes using argon-acetylene mixture and their application as IR sensor

    NASA Astrophysics Data System (ADS)

    Afzal, Rana Arslan; Afrin, Rahat; Manzoor, Umair; Bhatti, Arshad Saleem; Islam, Mohammad; Amin, Muhammad T.; Alazba, Abdulrahman A.

    2015-08-01

    Multi-walled carbon nanotubes (CNTs) were grown via pyrolytic chemical vapor deposition technique and explored for their infrared sensing behavior. CNT synthesis was carried out over cobalt zinc ferrite (Co0.5Zn0.5Fe2O4) catalyst nanoparticles under different gas flow conditions to control outside diameter of the nanotubes. It was found that a progressive decrease in the carbon precursor gas (acetylene in this case) from 5:1 to 9:1 (v/v) causes reduction of average CNT diameter from 85 nm to 635 nm. Growth conditions involving higher temperatures yield nanotubes/nanofibers with outer diameter of >500 nm, presumably due to surface aggregation of nanoparticles or increased flux of carbonaceous species at the catalyst surface or both. Current-voltage characteristics of the nanotubes depending on the CNT diameter, revealed linear or nonlinear behavior. When incorporated as sensing layer, the sensitivity of ˜5.3 was noticed with response time of ˜4.1 s. It is believed that IR sensing characteristics of such CNT-based detectors can be further enhanced through post-synthesis purification and chemical functionalization treatments.

  16. Measurement of Diameter Changes during Irradiation Testing

    SciTech Connect

    Davis, K. L.; Knudson, D. L.; Crepeau, J. C.; Solstad, S.

    2015-03-01

    New materials are being considered for fuel, cladding, and structures in advanced and existing nuclear reactors. Such materials can experience significant dimensional and physical changes during irradiation. Currently in the US, such changes are measured by repeatedly irradiating a specimen for a specified period of time and then removing it from the reactor for evaluation. The time and labor to remove, examine, and return irradiated samples for each measurement makes this approach very expensive. In addition, such techniques provide limited data and handling may disturb the phenomena of interest. In-pile detection of changes in geometry is sorely needed to understand real-time behavior during irradiation testing of fuels and materials in high flux US Material and Test Reactors (MTRs). This paper presents development results of an advanced Linear Variable Differential Transformer-based test rig capable of detecting real-time changes in diameter of fuel rods or material samples during irradiation in US MTRs. This test rig is being developed at the Idaho National Laboratory and will provide experimenters with a unique capability to measure diameter changes associated with fuel and cladding swelling, pellet-clad interaction, and crud buildup.

  17. OISL transmitter at 985 nm

    NASA Astrophysics Data System (ADS)

    Larose, Robert; Lauzon, Jocelyn; Mohrdiek, Stefan; Harder, Christoph S.; Changkakoti, Rupak; Park, Peter

    1999-04-01

    For high data rate (greater than 1 Gbps) Optical Inter- Satellite Link (OISL), a compact laser transmitter with high power and good efficiency is required. A trade-off analysis between the technologies such as the mature 840 nm laser diodes, 1064 nm diode-pumped solid state laser and the more recent 1550 nm Erbium Doped Fiber Amplifier (EDFA) is used to find the optical solution. The Si-APDs are preferred for their large detector areas and good noise figures which reduce the tracking requirements and simplify optical design of the receiver. Because of significant amount of power needed to close the link distance up to 7000 km (LEO-LEO), use of 840 nm diodes is limited. In this paper, we present an alternative system based on a system concept denoted as the SLYB (Semiconductor Laser Ytterbium Booster). The SLYB uses a polarization maintaining double-clad ytterbium fiber as a power amplifier. The device houses two semiconductor diodes that are designed to meet telecom reliability: a broad-area 917 nm pump diode and a directly modulated FP laser for signal generation. The output signal is in a linearly polarized state with an extinction ratio of 20 dB. The complete module (15 X 12 X 4.3 cm3) weighs less than 0.9 kg and delivers up to 27 dBm average output power at 985 nm. Designed primarily for direct detection using Si APDs, the transmitter offers a modulation data rate of at least 1.5 Gb/s with a modulation extinction ratio better than 13 dB. Total power consumption is expected to be lower than 8 W by using an uncooled pump laser. Preliminary radiation testing of the fiber indicates output power penalty of 1.5 dB at the end of 10 years in operation. We are presently investigating the fabrication of an improved radiation-hardened Yb-fiber for the final prototype to reduce this penalty. For higher data rate the design can be extended to a Wavelength Division Multiplexing (WDM) scheme adding multiple channels.

  18. Size and voltage dependence of effective anisotropy in sub-100-nm perpendicular magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Piotrowski, Stephan K.; Bapna, Mukund; Oberdick, Samuel D.; Majetich, Sara A.; Li, Mingen; Chien, C. L.; Ahmed, Rizvi; Victora, R. H.

    2016-07-01

    Magnetic tunnel junctions with perpendicular magnetic anisotropy are investigated using a conductive atomic force microscope. The 1.23 -nm Co40Fe40B20 recording layer coercivity exhibits a size dependence which suggests single-domain behavior for diameters ≤100 nm. Focusing on devices with diameters smaller than 100 nm, we determine the effect of voltage and size on the effective device anisotropy Keff using two different techniques. Keff is extracted both from distributions of the switching fields of the recording and reference layers and from measurement of thermal fluctuations of the recording layer magnetization when a field close to the switching field is applied. The results from both sets of measurements reveal that Keff increases monotonically with decreasing junction diameter, consistent with the size dependence of the demagnetization energy density. We demonstrate that Keff can be controlled with a voltage down to the smallest size measured, 64 nm.

  19. Composition of 15-85 nm particles in marine air

    NASA Astrophysics Data System (ADS)

    Lawler, M. J.; Whitehead, J.; O'Dowd, C.; Monahan, C.; McFiggans, G.; Smith, J. N.

    2014-11-01

    The chemical composition of 15-85 nm diameter particles was measured at Mace Head, Ireland, during May 2011 using the TDCIMS (thermal desorption chemical ionization mass spectrometer). Measurable levels of chloride, sodium, and sulfate were present in essentially all collected samples of these particles at this coastal Atlantic site. Acetaldehyde and benzoic acid were also frequently detected. Concomitant particle hygroscopicity observations usually showed a sea-salt mode and a lower hygroscopicity mode with growth factors near to that of ammonium sulfate. There were many periods lasting from hours to about 2 days during which the 10-60 nm particle number increased dramatically in polar oceanic air. These periods were correlated with the presence of benzoic acid in the particles and an increase in the number of lower hygroscopicity mode particles. Very small (< 10 nm) particles were also present, suggesting that new particle formation contributed to these nanoparticle enhancement events.

  20. High-index nanocomposite photoresist for 193-nm lithography

    NASA Astrophysics Data System (ADS)

    Bae, Woo Jin; Trikeriotis, Makros; Rodriguez, Robert; Zettel, Michael F.; Piscani, Emil; Ober, Christopher K.; Giannelis, Emmanuel P.; Zimmerman, Paul

    2009-03-01

    In immersion lithography, high index fluids are used to increase the numerical aperture (NA) of the imaging system and decrease the minimum printable feature size. Water has been used in first generation immersion lithography at 193 nm to reach the 45 nm node, but to reach the 38 and 32 nm nodes, fluids and resists with a higher index than water are needed. A critical issue hindering the implementation of 193i at the 32 nm node is the availability of high refractive index (n > 1.8) and low optical absorption fluids and resists. It is critical to note that high index resists are necessary only when a high refractive index fluid is in use. High index resist improves the depth of focus (DOF) even without high index fluids. In this study, high refractive index nanoparticles have been synthesized and introduced into a resist matrix to increase the overall refractive index. The strategy followed is to synthesize PGMEA-soluble nanoparticles and then disperse them into a 193 nm resist. High index nanoparticles 1-2 nm in diameter were synthesized by a combination of hydrolysis and sol-gel methods. A ligand exchange method was used, allowing the surface of the nanoparticles to be modified with photoresist-friendly moieties to help them disperse uniformly in the resist matrix. The refractive index and ultraviolet absorbance were measured to evaluate the quality of next generation immersion lithography resist materials.

  1. Carbon : nickel nanocomposite templates - predefined stable catalysts for diameter-controlled growth of single-walled carbon nanotubes.

    PubMed

    Melkhanova, Svetlana; Haluska, Miro; Hübner, René; Kunze, Tim; Keller, Adrian; Abrasonis, Gintautas; Gemming, Sibylle; Krause, Matthias

    2016-08-21

    Carbon : nickel (C : Ni) nanocomposite templates (NCTs) were used as catalyst precursors for diameter-controlled growth of single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition (CVD). Two NCT types of 2 nm thickness were prepared by ion beam co-sputtering without (type I) or with assisting Ar(+) ion irradiation (type II). NCT type I comprised Ni-rich nanoparticles (NPs) with defined diameter in an amorphous carbon matrix, while NCT type II was a homogenous C : Ni film. Based on the Raman spectra of more than 600 individual SWCNTs, the diameter distribution obtained from both types of NCT was determined. SWCNTs with a selective, monomodal diameter distribution are obtained from NCT type I. About 50% of the SWCNTs have a diameter of (1.36 ± 0.10) nm. In contrast to NCT type I, SWCNTs with a non-selective, relatively homogeneous diameter distribution from 0.80 to 1.40 nm covering 88% of all SWCNTs are obtained from NCT type II. From both catalyst templates predominantly separated as-grown SWCNTs are obtained. They are free of solvents or surfactants, exhibit a low degree of bundling and contain negligible amounts of MWCNTs. The study demonstrates the advantage of predefined catalysts for diameter-controlled SWCNT synthesis in comparison to in situ formed catalysts. PMID:27460394

  2. Inhibited bacterial biofilm formation and improved osteogenic activity on gentamicin-loaded titania nanotubes with various diameters.

    PubMed

    Lin, Wen-tao; Tan, Hong-lue; Duan, Zhao-ling; Yue, Bing; Ma, Rui; He, Guo; Tang, Ting-ting

    2014-01-01

    Titania nanotubes loaded with antibiotics can deliver a high concentration of antibiotics locally at a specific site, thereby providing a promising strategy to prevent implant-associated infections. In this study we have fabricated titania nanotubes with various diameters (80, 120, 160, and 200 nm) and 200 nm length via electrochemical anodization. These nanotubes were loaded with 2 mg of gentamicin using a lyophilization method and vacuum drying. A standard strain, Staphylococcus epidermidis (American Type Culture Collection 35984), and two clinical isolates, S. aureus 376 and S. epidermidis 389, were selected to investigate the anti-infective ability of the gentamicin-loaded nanotubes (NT-G). Flat titanium (FlatTi) and nanotubes with no drug loading (NT) were also investigated and compared. We found that NT-G could significantly inhibit bacterial adhesion and biofilm formation compared to FlatTi or NT, and the NT-G with 160 nm and 200 nm diameters had stronger antibacterial activity because of the extended drug release time of NT-G with larger diameters. The NT also exhibited greater antibacterial ability than the FlatTi, while nanotubes with 80 nm or 120 nm diameters had better effects. Furthermore, human marrow derived mesenchymal stem cells were used to evaluate the effect of nanotubular topographies on the osteogenic differentiation of mesenchymal stem cells. Our results showed that NT-G and NT, especially those with 80 nm diameters, significantly promoted cell attachment, proliferation, spreading, and osteogenic differentiation when compared to FlatTi, and there was no significant difference between NT-G and NT with the same diameter. Therefore, nanotube modification and gentamicin loading can significantly improve the antibacterial ability and osteogenic activity of orthopedic implants. PMID:24634583

  3. Diameter-dependent thermal-oxidative stability of single-walled carbon nanotubes synthesized by a floating catalytic chemical vapor deposition method

    NASA Astrophysics Data System (ADS)

    Ma, Jie; Yu, Fei; Yuan, Zhiwen; Chen, Junhong

    2011-10-01

    In this paper, purified single-walled carbon naotubes (SWCNTs) with three different diameters were synthesized using a floating catalytic chemical vapor deposition method with ethanol as carbon feedstock, ferrocene as catalyst, and thiophene as growth promoter. The thermal-oxidative stability of different-diameter SWCNTs was studied by using thermal analysis (TG, DTA), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analysis. The results indicate that small diameter SWCNTs (˜1 nm) are less stable and burn at lower temperature (610 °C), however, the larger diameter SWCNTs (˜5 nm) survive after burning at higher temperature (685 °C), the oxidation rate varies inversely with the tube diameter of SWCNTs, which may be concluded that the higher oxidation-resistant temperature of larger diameter SWCNTs can be attributed to the lower curvature-induced strain by rolling the planar graphene sheet for the larger diameter, so small tubes will become thermodynamically unstable.

  4. Optimization of electrospun TSF nanofiber alignment and diameter to promote growth and migration of mesenchymal stem cells

    NASA Astrophysics Data System (ADS)

    Qu, Jing; Zhou, Dandan; Xu, Xiaojing; Zhang, Feng; He, Lihong; Ye, Rong; Zhu, Ziyu; Zuo, Baoqi; Zhang, Huanxiang

    2012-11-01

    Silk fibroin scaffolds are a naturally derived biocompatible matrix with the potential for reconstructive surgical applications. In this study, tussah silk fibroin (TSF) nanofiber with different diameters (400 nm, 800 nm and 1200 nm) and alignment (random and aligned) were prepared by electrospinning, then the growth and migration of mesenchymal stem cells (MSCs) on these materials were further evaluated. CD90 immunofluorescence staining showed that fiber alignment exhibited a strong influence on the morphology of MSCs, indicating that the alignment of the scaffolds could determine the distribution of cells. Moreover, smaller diameter and aligned TSF scaffolds are more favorable to the growth of MSCs as compared with 800 nm and 1200 nm random TSF scaffolds. In addition, the increased migration speed and efficiency of MSCs induced by three-D TSF were verified, highlighting the guiding roles of TSF to the migrated MSCs. More importantly, 400 nm aligned TSF scaffolds dramatically improved cell migratory speed and further induced the most efficient migration of MSCs as compared with larger diameter TSF scaffolds. In conclusion, the data demonstrate that smaller diameter and aligned electrospun TSF represent valuable scaffolds for supporting and promoting MSCs growth and migration, thus raising the possibility of manipulating TSF scaffolds to enhance homing and therapeutic potential of MSCs in cellular therapy.

  5. Control of Separation and Diameter of Ag Nanorods through Self-organized Seeds.

    PubMed

    Elliott, Paul R; Stagon, Stephen P; Huang, Hanchen

    2015-01-01

    This paper proposes a mechanism of controlling the diameter and separation of metallic nanorods from physical vapor deposition through self-organized seeds and experimentally demonstrates the feasibility using Ag as the prototype metal, In as the seed, and Si the substrate. Being non-wetting on Si substrates, deposited In atoms self-organize into islands. Subsequently deposited Ag atoms attach to In islands, rather than to Si substrates, due to preferential bonding and geometrical shadowing. The experimental results show that self-organized In seeds of 5 nm nominal thickness give rise to the best separation and the smallest diameter of Ag nanorods. PMID:26585104

  6. Control of Separation and Diameter of Ag Nanorods through Self-organized Seeds

    PubMed Central

    Elliott, Paul R.; Stagon, Stephen P.; Huang, Hanchen

    2015-01-01

    This paper proposes a mechanism of controlling the diameter and separation of metallic nanorods from physical vapor deposition through self-organized seeds and experimentally demonstrates the feasibility using Ag as the prototype metal, In as the seed, and Si the substrate. Being non-wetting on Si substrates, deposited In atoms self-organize into islands. Subsequently deposited Ag atoms attach to In islands, rather than to Si substrates, due to preferential bonding and geometrical shadowing. The experimental results show that self-organized In seeds of 5 nm nominal thickness give rise to the best separation and the smallest diameter of Ag nanorods. PMID:26585104

  7. Thirty-centimeter-diameter ion milling source

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.

    1978-01-01

    A 30-cm beam diameter ion source has been designed and fabricated for micromachining and sputtering applications. An argon ion current density of 1 mA/cu cm at 500 eV ion energy was selected as a design operating condition. The completed ion source met the design criteria at this operating condition with a uniform and well-collimated beam having an average variation in current density of + or - 5% over the center of 20 cm of the beam. This ion source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. Langmuir probe surveys of the source plasma support the design concepts of a multipole field and a circumferential cathode to enhance plasma uniformity.

  8. Five meter diameter conical furlable antenna

    NASA Technical Reports Server (NTRS)

    Fortenberry, J. W.; Freeland, R. E.; Moore, D. M.

    1976-01-01

    An investigation was made to demonstrate that a 5-meter-diameter, furlable, conical reflector antenna utilizing a line source feed can be fabricated utilizing composite materials and to prove that the antenna can function mechanically and electrically as prototype flight hardware. The design, analysis, and testing of the antenna are described. An RF efficiency of 55% at 8.5 GHz and a surface error of 0.64 mm rms were chosen as basic design requirements. Actual test measurements yielded an efficiency of 53% (49.77 dB gain) and a surface error of 0.61 mm rms. Atmospherically induced corrosion of the reflector mesh resulted in the RF performance degradation. An assessment of the antenna as compared to the current state of the art technology was made. This assessment included cost, surface accuracy and RF performance, structural and mechanical characteristics, and possible applications.

  9. Development of fine diameter mullite fiber

    NASA Technical Reports Server (NTRS)

    Long, W. G.

    1974-01-01

    Results are presented of a program to develop and evaluate mullite fiber with a mean diameter under two microns. The two micron fiber is produced by a blowing process at room temperature from a low viscosity (10-25 poise) solution. The blown fiber was evaluated for dimensional stability in thermal cycling to 1371 C, and was equivalent to the 5 micron spun B and W mullite fiber. An additive study was conducted to evaluate substitutes for the boron. Three levels of chromium, lithium fluoride, and magnesium were added to the standard composition in place of boron and the fiber produced was evaluated for chemical and dimensional stability in thermal cycling to 1371 C. The magnesium was the most chemically stable, but the chrome additive imparted the best dimensional stability.

  10. Fire protection covering for small diameter missiles

    NASA Technical Reports Server (NTRS)

    Riccitiello, S. R.; Sawko, P. M. (Inventor)

    1979-01-01

    Flexible intumescent protection sheeting of unusually uniform thickness were prepared from epoxy-polysulfide compositions, containing microfibers and the ammonium salt of 1,4-nitroaniline-2-sulfonic acid, as disclosed in U.S. Pat. No. 3,663,464, except that an ammonium salt particle size in the order of 5 to 8 microns and a fiber size of about 1/128th inch in length and 3 to 5 microns in diameter were found critical to obtain the required density of 1.46 to 1.50 g/cc. The insulation sheeting was prepared by a continuous process involving vacuum mixing, calendering, and curing under very strict conditions which depend to some extent upon the thickness of the sheet produced.

  11. Granulation, Irradiance and Diameter Solar Variations

    NASA Astrophysics Data System (ADS)

    Humberto Andrei, Alexandre; Calderari Boscardin, Sergio; Lousada Penna, Jucira; Reis Neto, Eugenio

    2015-08-01

    Though granulation forms the very face of sun’s photosphere, there are no long term registers of it. Observational and computational hardships to define and follow such highly variable “face” have so far prevented the realization of those registers. However, in recent years a large, coherent body of white light images became available. We retrieved white light, full solar disk images from the BBSO, to a total of 1104 treated ones and 1245 treated and compensated for limb darkening ones. The time coverage extends from the year 2000 to 2005, thus covering the rise and fall of the solar cycle 23. For the analysis, only the central 0.35R portion of the Sun was considered. The central portion was then divided into 100 subsectors, to average and discard the deviant results. The analysis goal is to derive the long term behavior of the photosphere granulation, in broad statistical sense. Three statistics were this way calculated: the standard deviation of the counts (that answers to the grains size); the counts difference between the maximum and minimum tenths (that answers to the grains brightness); the degree of the best fit polynomial along lines and columns (that answers to the grains numbers). According to the statistics, there is no significant variation in the number of grains. The grains sizes are the largest by the solar maximum, in excellent agreement with the maximum of the measured diameter. The grains brightness, on the contrary, is minimum at the solar maximum, and again an excellent agreement is verified with the maximum of the measured diameter.

  12. Comparison of 885 nm pumping and 808 nm pumping in Nd:CNGG laser operating at 1061 nm and 935 nm

    NASA Astrophysics Data System (ADS)

    Shi, Yuxian; Li, Qinan; Zhang, Dongxiang; Feng, Baohua; Zhang, Zhiguo; Zhang, Huaijin; Wang, Jiyang

    2010-07-01

    A Nd:CNGG laser operated at 935 nm and 1061 nm pumped at 885 nm and 808 nm, respectively, is demonstrated. The 885 nm direct pumping scheme shows some advantages over the 808 nm traditional pumping scheme. It includes higher slope efficiency, lower threshold, and better beam quality at high output power. With the direct pumping, the slope efficiency increases by 43% and the threshold decreases by 10% compared with traditional pumping in the Nd:CNGG laser operated at 935 nm. When the Nd:CNGG laser operates at 1061 nm, the direct pumping increases the slope efficiency by 14% with a 20% reduction in the oscillation threshold.

  13. Tissue engineered small-diameter vascular grafts.

    PubMed

    Schmedlen, Rachael H; Elbjeirami, Wafa M; Gobin, Andrea S; West, Jennifer L

    2003-10-01

    Arterial occlusive disease remains the leading cause of death in western countries and often requires vascular reconstructive surgery. The limited supply of suitable small-diameter vascular grafts has led to the development of tissue engineered blood vessel substitutes. Many different approaches have been examined, including natural scaffolds containing one or more ECM proteins and degradable polymeric scaffolds. For optimal graft development, many efforts have modified the culture environment to enhance ECM synthesis and organization using bioreactors under physiologic conditions and biochemical supplements. In the past couple of decades, a great deal of progress on TEVGs has been made. Many challenges remain and are being addressed, particularly with regard to the prevention of thrombosis and the improvement of graft mechanical properties. To develop a patent TEVG that grossly resembles native tissue, required culture times in most studies exceed 8 weeks. Even with further advances in the field, TEVGs will likely not be used in emergency situations because of the time necessary to allow for cell expansion, ECM production and organization, and attainment of desired mechanical strength. Furthermore, TEVGs will probably require the use of autologous tissue to prevent an immunogenic response, unless advances in immune acceptance render allogenic and xenogenic tissue use feasible. TEVGs have not yet been subjected to clinical trials, which will determine the efficacy of such grafts in the long term. Finally, off-the-shelf availability and cost will become the biggest hurdles in the development of a feasible TEVG product. Although many obstacles exist in the effort to develop a small-diameter TEVG, the potential benefits of such an achievement are exciting. In the near future, a nonthrombogenic TEVG with sufficient mechanical strength may be developed for clinical trials. Such a graft will have the minimum characteristics of biological tissue necessary to remain patent

  14. Diameter control of single wall carbon nanotubes synthesized using chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Roy, Soumyendu; Bajpai, Reeti; Soin, Navneet; Roy, Susanta Sinha; McLaughlin, James A.; Misra, D. S.

    2014-12-01

    Lack of control on the chirality or diameter of single-wall carbon nanotubes (SWCNTs) during synthesis is a major impediment in the path of their widespread commercialization. We demonstrate that the humble technique of catalytic chemical vapor deposition of methane, without any sophisticated catalyst preparation, can provide significant control on the diameter of the synthesized SWCNTs. The catalyst used is a solid solution of the bimetals Fe-Mo or Co-Mo in MgO. The radial breathing modes (RBMs) in the Raman spectra of SWCNTs were used to find out the diameters. Kataura plot along with RBMs was used to study the chirality of the tubes. High concentration of the catalysts (Co:Mo:MgO = 1:0.5:15 and Fe:Mo:MgO = 1:0.5:30) resulted in high yields. However, most of these carbonaceous materials were impurities. Reducing the concentration not only improved the purity and crystallinity (ID/IG ratio ∼0.1), but most importantly reduced the diameter spread of the SWCNTs. Majority of the SWCNTs grown using the low concentration catalysts (Co:Mo:MgO = 1:0.5:300 and Fe:Mo:MgO = 1:0.5:200) were estimated to have diameters lying between 1.13 and 1.65 nm. This narrowing of diameter spread happened for both Fe and Co catalyst systems and depended only on the concentration of the catalyst.

  15. Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts

    NASA Astrophysics Data System (ADS)

    Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

    2016-01-01

    We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high

  16. Variation of nanopore diameter along porous anodic alumina channels by multi-step anodization.

    PubMed

    Lee, Kwang Hong; Lim, Xin Yuan; Wai, Kah Wing; Romanato, Filippo; Wong, Chee Cheong

    2011-02-01

    In order to form tapered nanocapillaries, we investigated a method to vary the nanopore diameter along the porous anodic alumina (PAA) channels using multi-step anodization. By anodizing the aluminum in either single acid (H3PO4) or multi-acid (H2SO4, oxalic acid and H3PO4) with increasing or decreasing voltage, the diameter of the nanopore along the PAA channel can be varied systematically corresponding to the applied voltages. The pore size along the channel can be enlarged or shrunken in the range of 20 nm to 200 nm. Structural engineering of the template along the film growth direction can be achieved by deliberately designing a suitable voltage and electrolyte together with anodization time. PMID:21456152

  17. LED-based digital diameter measurement

    NASA Astrophysics Data System (ADS)

    Kleuver, Wolfram; Becker, Lothar

    1995-01-01

    This paper presents a new industrial sensor for measuring diameters of extreme thin objects. The system is divided in two parts. The first is the emitter and the second the receiver. It is possible to use this system for the automatic inspection of files and wires in the textile industries and wire works. Another application for the sensor is the control of production of chemical files in an extruder. Furthermore we can measure more than one object in the lightbeam because we get information not only about the dimensions also about the position of the objects in the beam. The innovation in this system is the using of a light emitting diode (LED) as emitter and the realization of a long distance of about two or more meters between the two sensorheads. The results of this development are a special kind of optical layout in the emitter to reduce the loss of intensity and minimize the divergence of the lightbeam. It is not necessary to develop an intensity distribution, which is equal over the complete width of the sensorhead. We can show that we have a better dynamic in the system with this feature. The experiments prove that we get the same resolution as a laserbeamsensor. Furthermore one advantage is the eye-safety.

  18. The 15 cm diameter ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1974-01-01

    The startup reliability of a 15 cm diameter mercury bombardment ion thruster which employs a pulsed high voltage tickler electrode on the main and neutralizer cathodes is examined. Startup of the thruster is achieved 100% of the time on the main cathode and 98.7% of the time on the neutralizer cathode over a 3640 cycle test. The thruster was started from a 20 C initial condition and operated for an hour at a 600 mA beam current. An energy efficiency of 75% and a propellant utilization efficiency of 77% was achieved over the complete cycle. The effect of a single cusp magnetic field thruster length on its performance is discussed. Guidelines are formulated for the shaping of magnetic field lines in thrusters. A model describing double ion production in mercury discharges is presented. The production route is shown to occur through the single ionic ground state. Photographs of the interior of an operating-hollow cathode are presented. A cathode spot is shown to be present if the cathode is free of low work-function surfaces. The spot is observed if a low work-function oxide coating is applied to the cathode insert. Results show that low work-function oxide coatings tend to migrate during thruster operation.

  19. Large Circular Basin - 1300-km diameter

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Close-up view of one-half of a 1300-km diameter circular basin the largest observed on Mercury. The other half is hidden beyond the terminator to the left. Hills and valleys extend in a radial fashion outward from the main ring. Interior of the large basin is completely flooded by plains materials; adjacent lowlands are also partially flooded and superimposed on the plains are bowl shaped craters. Wrinkle ridges are abundant on the plains materials. The area shown is 1008 miles (1600 km) from the top to the bottom of the picture. Sun's illumination is from the right. Blurred linear lines extending across the picture near bottom are missing data lines that have been filled in by the computer. Mariner 10 encountered Mercury on Friday, March 29th, 1974, passing the planet on the darkside 431 miles (690-km) from the surface.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    NOTE: This image was scanned from physical media.

  20. Do Shale Pore Throats Have a Threshold Diameter for Oil Storage?

    NASA Astrophysics Data System (ADS)

    Zou, Caineng; Jin, Xu; Zhu, Rukai; Gong, Guangming; Sun, Liang; Dai, Jinxing; Meng, Depeng; Wang, Xiaoqi; Li, Jianming; Wu, Songtao; Liu, Xiaodan; Wu, Juntao; Jiang, Lei

    2015-08-01

    In this work, a nanoporous template with a controllable channel diameter was used to simulate the oil storage ability of shale pore throats. On the basis of the wetting behaviours at the nanoscale solid-liquid interfaces, the seepage of oil in nano-channels of different diameters was examined to accurately and systematically determine the effect of the pore diameter on the oil storage capacity. The results indicated that the lower threshold for oil storage was a pore throat of 20 nm, under certain conditions. This proposed pore size threshold provides novel, evidence-based criteria for estimating the geological reserves, recoverable reserves and economically recoverable reserves of shale oil. This new understanding of shale oil processes could revolutionize the related industries.

  1. Do Shale Pore Throats Have a Threshold Diameter for Oil Storage?

    PubMed Central

    Zou, Caineng; Jin, Xu; Zhu, Rukai; Gong, Guangming; Sun, Liang; Dai, Jinxing; Meng, Depeng; Wang, Xiaoqi; Li, Jianming; Wu, Songtao; Liu, Xiaodan; Wu, Juntao; Jiang, Lei

    2015-01-01

    In this work, a nanoporous template with a controllable channel diameter was used to simulate the oil storage ability of shale pore throats. On the basis of the wetting behaviours at the nanoscale solid-liquid interfaces, the seepage of oil in nano-channels of different diameters was examined to accurately and systematically determine the effect of the pore diameter on the oil storage capacity. The results indicated that the lower threshold for oil storage was a pore throat of 20 nm, under certain conditions. This proposed pore size threshold provides novel, evidence-based criteria for estimating the geological reserves, recoverable reserves and economically recoverable reserves of shale oil. This new understanding of shale oil processes could revolutionize the related industries. PMID:26314637

  2. High-performance radio frequency transistors based on diameter-separated semiconducting carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cao, Yu; Che, Yuchi; Seo, Jung-Woo T.; Gui, Hui; Hersam, Mark C.; Zhou, Chongwu

    2016-06-01

    In this paper, we report the high-performance radio-frequency transistors based on the single-walled semiconducting carbon nanotubes with a refined average diameter of ˜1.6 nm. These diameter-separated carbon nanotube transistors show excellent transconductance of 55 μS/μm and desirable drain current saturation with an output resistance of ˜100 KΩ μm. An exceptional radio-frequency performance is also achieved with current gain and power gain cut-off frequencies of 23 GHz and 20 GHz (extrinsic) and 65 GHz and 35 GHz (intrinsic), respectively. These radio-frequency metrics are among the highest reported for the carbon nanotube thin-film transistors. This study provides demonstration of radio frequency transistors based on carbon nanotubes with tailored diameter distributions, which will guide the future application of carbon nanotubes in radio-frequency electronics.

  3. Puffing and inhalation behaviour in cigarette smoking: Implications for particle diameter and dose

    NASA Astrophysics Data System (ADS)

    Dickens, Colin; McGrath, Conor; Warren, Nigel; Biggs, Philip; McAughey, John

    2009-02-01

    Inhalation of tobacco smoke aerosol is a two-step process involving puffing followed by inhalation. Measured smoke deposition efficiencies in the lung (20-70%) are greater than expected for smoke particles of diameter 150 -- 250 nm CMD. Various mechanisms have been put forward to explain this enhanced deposition pattern, including coagulation, hygroscopic growth, condensation and evaporation, changes in composition, or changes in inhalation behaviour. This paper represents one of a series of studies seeking to better quantify smoke chemistry, inhalation behaviour and cumulative particle growth. The studies have been conducted to better understand smoke dosimetry and links to disease as part of a wider programme defining risk and potential harm reduction. In this study, it was noted that particle deposition increased with increasing inhalation depth, and that smoke inhalation volumes were generally greater than normal tidal breathing volumes. A weak association was observed between particle diameter and puff flow, but no strong association between particle diameter and retention efficiency.

  4. Ion transport in sub-5-nm graphene nanopores

    NASA Astrophysics Data System (ADS)

    Suk, Myung E.; Aluru, N. R.

    2014-02-01

    Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors.

  5. Ion transport in sub-5-nm graphene nanopores

    SciTech Connect

    Suk, Myung E.; Aluru, N. R.

    2014-02-28

    Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors.

  6. Sub-100-nm ordered silicon hole arrays by metal-assisted chemical etching

    PubMed Central

    2013-01-01

    Sub-100-nm silicon nanohole arrays were fabricated by a combination of the site-selective electroless deposition of noble metals through anodic porous alumina and the subsequent metal-assisted chemical etching. Under optimum conditions, the formation of deep straight holes with an ordered periodicity (e.g., 100 nm interval, 40 nm diameter, and high aspect ratio of 50) was successfully achieved. By using the present method, the fabrication of silicon nanohole arrays with 60-nm periodicity was also achieved. PMID:24090268

  7. Control gate length, spacing, channel hole diameter, and stacked layer number design for bit-cost scalable-type three-dimensional stackable NAND flash memory

    NASA Astrophysics Data System (ADS)

    Miyaji, Kousuke; Yanagihara, Yuki; Hirasawa, Reo; Ning, Sheyang; Takeuchi, Ken

    2014-02-01

    A cell design for three-dimensional (3D) stackable NAND (3D NAND) flash memory are investigated with emphases on control gate length (Lg), spacing (Lspace) and channel hole diameter (Φ). The requirements for the Lg and Lspace are derived from the 3D device simulation and the effective cell size that competes with the planar NAND. The simulations reveal that Lg = Lspace = 20 nm (40 nm layer pitch) is achievable for bit-cost scalable (BiCS)-type 3D NAND with the 90 nm diameter hole. If the number of stacked layers is 22 with the layer pitch of 40 nm, the effective cell size of the 3D NAND corresponds to that of 15 nm planar NAND technology. Furthermore, cell characteristics of the macaroni body channel with various Φ are investigated. Although macaroni body channel improves cell characteristics at Φ = 90 nm, a cell with Φ = 60 nm without macaroni body structure shows better characteristics.

  8. Effect of nanotube diameters on bioactivity of a multifunctional titanium alloy

    NASA Astrophysics Data System (ADS)

    Hao, Y. Q.; Li, S. J.; Hao, Y. L.; Zhao, Y. K.; Ai, H. J.

    2013-03-01

    Ti-24Nb-4Zr-8Sn (abbreviated as Ti2448) is a multifunctional β type titanium alloy consisting of nontoxic alloying elements and possessing better balanced biomechanical properties of high strength and low elastic modulus. To improve its bioactivity, the anodic oxidation of Ti2448 alloy in neutral electrolyte containing small amounts of NH4F was applied to produce the nanotubes consisting of the amorphous mixed oxides of TiO2, Nb2O5, SnO2 and ZrO2. The in vitro studies of the oestoblast-like MG-63 cells were performed to evaluate the biological behavior of the nanotubes with the outer diameters of 30, 50, 70 and 90 nm in comparison with the polished pure titanium and Ti2448 alloy. The results showed that the smaller diameter of 30 nm promoted the cell adhesion, proliferation and differentiation whereas the larger diameter of 90 nm had the worst cell viability with small spreading area of cytoskeletal actin. Although the nanotubes of Ti2448 alloy consist of the amorphous mixed oxides, it exhibits similar biological behavior with that of the amorphous TiO2 of pure titanium. This suggests that the topography of the amorphous nanotube plays important role on cell response. Additionally, the studies did not detect statistical difference of the bioactivity for the polished pure titanium and Ti2448 alloy.

  9. Method of synthesizing small-diameter carbon nanotubes with electron field emission properties

    NASA Technical Reports Server (NTRS)

    Liu, Jie (Inventor); Du, Chunsheng (Inventor); Qian, Cheng (Inventor); Gao, Bo (Inventor); Qiu, Qi (Inventor); Zhou, Otto Z. (Inventor)

    2009-01-01

    Carbon nanotube material having an outer diameter less than 10 nm and a number of walls less than ten are disclosed. Also disclosed are an electron field emission device including a substrate, an optionally layer of adhesion-promoting layer, and a layer of electron field emission material. The electron field emission material includes a carbon nanotube having a number of concentric graphene shells per tube of from two to ten, an outer diameter from 2 to 8 nm, and a nanotube length greater than 0.1 microns. One method to fabricate carbon nanotubes includes the steps of (a) producing a catalyst containing Fe and Mo supported on MgO powder, (b) using a mixture of hydrogen and carbon containing gas as precursors, and (c) heating the catalyst to a temperature above 950.degree. C. to produce a carbon nanotube. Another method of fabricating an electron field emission cathode includes the steps of (a) synthesizing electron field emission materials containing carbon nanotubes with a number of concentric graphene shells per tube from two to ten, an outer diameter of from 2 to 8 nm, and a length greater than 0.1 microns, (b) dispersing the electron field emission material in a suitable solvent, (c) depositing the electron field emission materials onto a substrate, and (d) annealing the substrate.

  10. The variation of surface contact angles according to the diameter of carbon nanotubes.

    PubMed

    Choi, Eun Chang; Choi, Won Seok; Hong, Byungyou

    2009-06-01

    The shape of CNTs is affected by various growth parameters such as reaction time, temperature, working power, and pressure as well as the type of catalytic layer and synthesis method. In this work, the thickness of Ni catalyst layer was varied to control the diameter of synthesized CNT. Ni catalyst layer was prepared using a DC magnetron sputtering method and the layer thickness was varied from 40 nm to 100 nm with the increment of 20 nm. And CNTs were grown on Ni catalyst layer using the hot-filament plasma enhanced chemical vapor deposition (HF-PECVD) with ammonia (NH3) gas for pretreatment and acetylene (C2H2) gas for the synthesis. The shape of the resulting CNTs was analyzed using field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). The surface contact angle of well-aligned CNTs was correlated with the diameter of CNT. As determined by contact angle measurement, the surface of CNT forests became more hydrophilic as the diameter of CNT increased. PMID:19504923

  11. Effect of Fiber Diameter on the Spreading, Proliferation and Differentiation of Chondrocytes on Electrospun Chitosan Matrices

    PubMed Central

    Noriega, Sandra E.; Hasanova, Gulnara I.; Schneider, Min Jeong; Larsen, Gustavo F.; Subramanian, Anuradha

    2012-01-01

    Tissue-engineered neocartilage with appropriate biomechanical properties holds promise not only for graft applications but also as a model system for controlled studies of chondrogenesis. Our objective in the present research study is to better understand the impact of fiber diameter on the cellular activity of chondrocytes cultured on nanofibrous matrices. By using the electrospinning process, fibrous scaffolds with fiber diameters ranging from 300 nm to 1 μm were prepared and the physicomechanical properties of the scaffolds were characterized. Bovine articular chondrocytes were then seeded and maintained on the scaffolds for 7 and 14 days in culture. An upregulation in the gene expression of collagen II was noted with decreasing fiber diameters. For cells that were cultured on scaffolds with a mean fiber diameter of 300 nm, a 2-fold higher ratio of collagen II/collagen I was noted when compared to cells cultured on sponge-like scaffolds prepared by freeze drying and lyophilization. Integrin (α5, αv, β1) gene expression was also observed to be influenced by matrix morphology. Our combined results suggest that matrix geometry can regulate and promote the retention of the chondrocyte genotype. PMID:21540560

  12. Fabrication of sub-15 nm aluminum wires by controlled etching

    NASA Astrophysics Data System (ADS)

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; McQueen, T. M.; Marković, N.

    2014-04-01

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  13. Instability of Reference Diameter in the Evaluation of Stenosis After Coronary Angioplasty: Percent Diameter Stenosis Overestimates Dilative Effects Due to Reference Diameter Reduction

    SciTech Connect

    Hirami, Ryouichi; Iwasaki, Kohichiro; Kusachi, Shozo; Murakami, Takashi; Hina, Kazuyoshi; Matano, Shigeru; Murakami, Masaaki; Kita, Toshimasa; Sakakibara, Noburu; Tsuji, Takao

    2000-03-15

    Purpose: To examine changes in the reference segment luminal diameter after coronary angioplasty.Methods: Sixty-one patients with stable angina pectoris or old myocardial infarction were examined. Coronary angiograms were recorded before coronary angioplasty (pre-angioplasty) and immediately after (post-angioplasty), as well as 3 months after. Artery diameters were measured on cine-film using quantitative coronary angiographic analysis.Results: The diameters of the proximal segment not involved in the balloon inflation and segments in the other artery did not change significantly after angioplasty, but the reference segment diameter significantly decreased (4.7%). More than 10% luminal reduction was observed in seven patients (11%) and more than 5% reduction was observed in 25 patients (41%). More than 5% underestimation of the stenosis was observed in 22 patients (36%) when the post-angioplasty reference diameter was used as the reference diameter, compared with when the pre-angioplasty measurement was used and more than 10% underestimation was observed in five patients (8%).Conclusion: This study indicated that evaluation by percent diameter stenosis, with the reference diameter from immediately after angioplasty, overestimates the dilative effects of coronary angioplasty, and that it is thus better to evaluate the efficacy of angioplasty using the absolute diameter in addition to percent luminal stenosis.

  14. Nineteen-Foot Diameter Explosively Driven Blast Simulator

    SciTech Connect

    VIGIL,MANUEL G.

    2001-07-01

    This report describes the 19-foot diameter blast tunnel at Sandia National Laboratories. The blast tunnel configuration consists of a 6 foot diameter by 200 foot long shock tube, a 6 foot diameter to 19 foot diameter conical expansion section that is 40 feet long, and a 19 foot diameter test section that is 65 feet long. Therefore, the total blast tunnel length is 305 feet. The development of this 19-foot diameter blast tunnel is presented. The small scale research test results using 4 inch by 8 inch diameter and 2 foot by 6 foot diameter shock tube facilities are included. Analytically predicted parameters are compared to experimentally measured blast tunnel parameters in this report. The blast tunnel parameters include distance, time, static, overpressure, stagnation pressure, dynamic pressure, reflected pressure, shock Mach number, flow Mach number, shock velocity, flow velocity, impulse, flow duration, etc. Shadowgraphs of the shock wave are included for the three different size blast tunnels.

  15. Effects of nanopillar array diameter and spacing on cancer cell capture and cell behaviors

    NASA Astrophysics Data System (ADS)

    Wang, Shunqiang; Wan, Yuan; Liu, Yaling

    2014-10-01

    While substrates with nanopillars (NPs) have emerged as promising platforms for isolation of circulating tumor cells (CTCs), the influence of diameter and spacing of NPs on CTC capture is still unclear. In this paper, CTC-capture yield and cell behaviors have been investigated by using antibody functionalized NPs of various diameters (120-1100 nm) and spacings (35-800 nm). The results show a linear relationship between the cell capture yield and effective contact area of NP substrates where a NP array of small diameter and reasonable spacing is preferred; however, spacing that is too small or too large adversely impairs the capture efficiency and specificity, respectively. In addition, the formation of pseudopodia between captured cells and the substrate is found to be dependent not only on cell adhesion status but also on elution strength and shear direction. These findings provide essential guidance in designing NP substrates for more efficient capture of CTCs and manipulation of cytomorphology in future.While substrates with nanopillars (NPs) have emerged as promising platforms for isolation of circulating tumor cells (CTCs), the influence of diameter and spacing of NPs on CTC capture is still unclear. In this paper, CTC-capture yield and cell behaviors have been investigated by using antibody functionalized NPs of various diameters (120-1100 nm) and spacings (35-800 nm). The results show a linear relationship between the cell capture yield and effective contact area of NP substrates where a NP array of small diameter and reasonable spacing is preferred; however, spacing that is too small or too large adversely impairs the capture efficiency and specificity, respectively. In addition, the formation of pseudopodia between captured cells and the substrate is found to be dependent not only on cell adhesion status but also on elution strength and shear direction. These findings provide essential guidance in designing NP substrates for more efficient capture of CTCs

  16. Extrusion of small-diameter, thin-wall tungsten tubing

    NASA Technical Reports Server (NTRS)

    Blankenship, C. P.; Gyorgak, C. A.

    1967-01-01

    Small-diameter, thin-wall seamless tubing of tungsten has been fabricated in lengths of up to 10 feet by hot extrusion over a floating mandrel. Extrusion of 0.50-inch-diameter tubing over 0.4-inch-diameter mandrels was accomplished at temperatures ranging from 3000 degrees to 4000 degrees F.

  17. High-aspect-ratio and highly ordered 15-nm porous alumina templates.

    PubMed

    Martín, Jaime; Manzano, Cristina V; Caballero-Calero, Olga; Martín-González, Marisol

    2013-01-01

    Ordered anodic aluminum oxide (AAO) templates with pores <15 nm in diameter and an aspect ratio (length-to-diameter ratio) above 3 × 10(3) have been fabricated using a nonlithographic approach; specifically, by anodizing aluminum in an ethylene-glycol-containing sulfuric acid electrolyte. The pores are the smallest in diameter reported for a self-ordered AAO without pore aspect-ratio limitations and good ordering, which opens up the possibility of obtaining nanowire arrays in the quantum confinement regime that is of interest for efficient thermoelectric generators. The effect of the ethylene glycol addition on both the pore diameter and the ordering is evaluated and discussed. Moreover, 15-nm-diameter Bi(2)Te(3) and poly(3-hexyl thiophene) (P3HT) nanowires have been prepared using these AAO templates. As known, Bi(2)Te(3) is currently the most efficient thermoelectric bulk material for room-temperature operations and, according with theory, its Seebeck coefficient should be increased when it is confined to nanowires with diameters close to 10 nm. On the other hand, P3HT is one of the main candidates for integrating organic photovoltaic and thermoelectric devices, and its properties are also proposed to increase when it is confined to nanoscale structures, mainly due to molecular orientation effects. PMID:23215033

  18. Sub-180 nm generation with borate crystal

    NASA Astrophysics Data System (ADS)

    Qu, Chen; Yoshimura, Masashi; Tsunoda, Jun; Kaneda, Yushi; Imade, Mamoru; Sasaki, Takatomo; Mori, Yusuke

    2014-10-01

    We demonstrated a new scheme for the generation of 179 nm vacuum-ultraviolet (VUV) light with an all-solid-state laser system. It was achieved by mixing the deep-ultraviolet (DUV) of 198.8 nm and the infrared (IR) of 1799.9 nm. While CsB3O5 (CBO) did not satisfy the phase-matching at around 180 nm, 179 nm output was generated with LiB3O5 (LBO) for the first time. The phase-matching property of LBO at around 180 nm was also investigated. There was small deviation from theoretical curve in the measurement, which is still considered reasonable.

  19. 147-nm photolysis of disilane

    SciTech Connect

    Perkins, G.G.A.; Lampe, F.W.

    1980-05-21

    The photodecomposition of Si/sub 2/H/sub 6/ at 147 nm results in the formation of H/sub 2/, SiH/sub 4/, Si/sub 3/H/sub 8/, Si/sub 4/H/sub 10/, Si/sub 5/H/sub 12/, and a solid film of amorphous silicon hydride (a-Si:H). Three primary processes are proposed to account for the results, namely, (a) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. SiH/sub 2/ + SiH/sub 3/ + H (phi/sub a/ = 0.61); (b) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. SiH/sub 3/SiH + 2H (phi/sub b/ = 0.18); (c) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. Si/sub 2/H/sub 5/ + H (phi/sub c/ = 0.21). The overall quantum yields depend on the pressure but at 1 Torr partial pressure of Si/sub 2/H/sub 6/ are PHI(-Si/sub 2/H/sub 6/) = 4.3 +- 0.2, PHI(SiH/sub 4/) = 1.2 +- 0.4, PHI(Si/sub 3/H/sub 8/) = 0.91 +- 0.08, PHI(Si/sub 4/H/sub 10/) = 0.62 +- 0.03, PHI(Si,wall) = 2.2. Quantum yields for H/sub 2/ formation were not measured. A mechanism is proposed which is shown to be in accord with the experimental facts.

  20. Control of the Diameter and Chiral Angle Distributions during Production of Single-wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel; Holmes, William; Sosa, Edward; Boul, Peter; Arepalli, Sivaram; Yowell, Leonard

    2008-01-01

    Many applications of single wall carbon nanotubes (SWCNT), especially in microelectronics, will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.). However, as produced SWCNT samples are polydispersed, with many (n,m) types present and typical approximate 1:2 metal/semiconductor ratio. It has been recognized that production of SWCNTs with narrow 'tube type populations' is beneficial for their use in applications, as well as for the subsequent sorting efforts. In the present work, SWCNTs were produced by a pulsed laser vaporization (PLV) technique. The nanotube type populations were studied with respect to the production temperature with two catalyst compositions: Co/Ni and Rh/Pd. The nanotube type populations were measured via photoluminescence, UV-Vis-NIR absorption and Raman spectroscopy. It was found that in the case of Co/Ni catalyst, decreased production temperature leads to smaller average diameter, exceptionally narrow diameter distribution, and strong preference toward (8,7) nanotubes. The other nanotubes present are distributed evenly in the 7-30 deg chiral angle range. In the case of Rh/Pd catalyst, a decrease in the temperature leads to a small decrease in the average diameter, with the chiral angle distribution skewed towards 30 o and a preference toward (7,6), (8,6) and (8,7) nanotubes. However, the diameter distribution remains rather broad. These results demonstrate that PLV production technique can provide at least partial control over the nanotube (n,m) populations. In addition, these results have implications for the understanding the nanotube nucleation mechanism in the laser oven.

  1. Diameter dependence of the fine structure of the Raman G-band of single wall carbon nanotubes revealed by a Kohonen self-organizing map

    NASA Astrophysics Data System (ADS)

    Kukovecz, A.; Smolik, M.; Bokova, S. N.; Kataura, H.; Achiba, Y.; Kuzmany, H.

    2003-11-01

    The Raman G-band of six single wall carbon nanotube samples with known diameters between 1.05 and 1.56 nm was measured with 14 different lasers in the 457-676 nm range. Spectra were reduced in size by discrete cosine transformation and introduced as input vectors into a Kohonen self-organizing map (SOM). Even though no diameter data was supplied to the network, the SOM was able to identify spectra belonging to the same sample. The results correlated well with those obtained by conventional cluster analysis. This suggests that artificial neural networks are capable of extracting diameter information from the G-band fine structure.

  2. Combination of transmission electron and atomic force microscopy techniques to determine volume equivalent diameter of submicrometer particles.

    PubMed

    Tumolva, Laarnie; Park, Ji-Yeon; Park, Kihong

    2012-04-01

    Morphological properties of atmospheric particles are directly related to their residence time and transport behaviors, and their deposition patterns in human respiratory systems. The projected properties of particles measured by transmission electron microscopy (TEM) were combined with the particle height measured by atomic force microscopy (AFM) to determine volume equivalent diameter of submicrometer particles. For nonvolatile (refractory) laboratory-generated spherical polystyrene latex and cubic NaCl particles, the measured volume equivalent diameters agreed well with the true values (within 4%). However, for nonrefractory (NH(4))(2)SO(4) particles, the measured volume equivalent diameter was much smaller than the true value due to evaporation of volatile species at low vacuum pressure and high electron-beam intensity conditions in TEM, and deformation of particles in AFM. We observed that the volume equivalent diameter of 100 nm mobility-classified atmospheric particles was 35 ± 5 nm, suggesting that these particles contain nonrefractory species, whereas that of 20 nm mobility-classified atmospheric particles was found to be 19 ± 6 nm, suggesting that these particles were refractory and spherical. PMID:21919129

  3. Diameter-sensitive biocompatibility of anodic TiO2 nanotubes treated with supercritical CO2 fluid

    PubMed Central

    2013-01-01

    This work reports on the diameter-sensitive biocompatibility of anodic TiO2 nanotubes with different nanotube diameters grown by a self-ordering process and subsequently treated with supercritical CO2 (ScCO2) fluid. We find that highly hydrophilic as-grown TiO2 nanotubes become hydrophobic after the ScCO2 treatment but can effectively recover their surface wettability under UV light irradiation as a result of photo-oxidation of C-H functional groups formed on the nanotube surface. It is demonstrated that human fibroblast cells show more obvious diameter-specific behavior on the ScCO2-treated TiO2 nanotubes than on the as-grown ones in the range of diameters of 15 to 100 nm. This result can be attributed to the removal of disordered Ti(OH)4 precipitates from the nanotube surface by the ScCO2 fluid, thus resulting in purer nanotube topography and stronger diameter dependence of cell activity. Furthermore, for the smallest diameter of 15 nm, ScCO2-treated TiO2 nanotubes reveal higher biocompatibility than the as-grown sample. PMID:23547743

  4. Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts.

    PubMed

    Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

    2016-01-21

    We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices. PMID:26690843

  5. Fiber diameter distributions in the chinchilla's ampullary nerves

    NASA Technical Reports Server (NTRS)

    Hoffman, Larry F.; Honrubia, Vicente

    2002-01-01

    A morphometric study of the chinchilla's ampullary nerves was conducted to produce an unbiased accounting of the diameter distribution of their constituent fibers. Diameter analyses were determined from 1 microm plastic-embedded nerve sections taken at a plane immediately proximal to the sensory epithelium. We found these nerves to be composed of 2094+/-573 fibers, having diameters that ranged from 0.5 to 8 microm. The distributions of diameters were positively skewed, where approximately 75% of the fibers were found to have diameters less than 3.5 microm. An analysis of the spatial distribution of diameters within the nerve section revealed that the lateralmost areas of the nerve contained larger fractions of fibers within the smallest diameter quintiles, and the central area harbored greater proportions of the larger diameter quintiles. However, significant fractions of all quintiles were found in all areas. These data were integrated with available data of Fernandez et al. (1998) to produce diameter estimates of calyx, dimorphic, and bouton morphology subpopulations. In view of a general relationship between diameter, innervation locus, and an afferent's physiologic characteristics, these data provide the basis for developing a perspective for the in situ distribution of afferent response dynamics.

  6. Carbon : nickel nanocomposite templates - predefined stable catalysts for diameter-controlled growth of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Melkhanova, Svetlana; Haluska, Miro; Hübner, René; Kunze, Tim; Keller, Adrian; Abrasonis, Gintautas; Gemming, Sibylle; Krause, Matthias

    2016-08-01

    Carbon : nickel (C : Ni) nanocomposite templates (NCTs) were used as catalyst precursors for diameter-controlled growth of single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition (CVD). Two NCT types of 2 nm thickness were prepared by ion beam co-sputtering without (type I) or with assisting Ar+ ion irradiation (type II). NCT type I comprised Ni-rich nanoparticles (NPs) with defined diameter in an amorphous carbon matrix, while NCT type II was a homogenous C : Ni film. Based on the Raman spectra of more than 600 individual SWCNTs, the diameter distribution obtained from both types of NCT was determined. SWCNTs with a selective, monomodal diameter distribution are obtained from NCT type I. About 50% of the SWCNTs have a diameter of (1.36 +/- 0.10) nm. In contrast to NCT type I, SWCNTs with a non-selective, relatively homogeneous diameter distribution from 0.80 to 1.40 nm covering 88% of all SWCNTs are obtained from NCT type II. From both catalyst templates predominantly separated as-grown SWCNTs are obtained. They are free of solvents or surfactants, exhibit a low degree of bundling and contain negligible amounts of MWCNTs. The study demonstrates the advantage of predefined catalysts for diameter-controlled SWCNT synthesis in comparison to in situ formed catalysts.Carbon : nickel (C : Ni) nanocomposite templates (NCTs) were used as catalyst precursors for diameter-controlled growth of single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition (CVD). Two NCT types of 2 nm thickness were prepared by ion beam co-sputtering without (type I) or with assisting Ar+ ion irradiation (type II). NCT type I comprised Ni-rich nanoparticles (NPs) with defined diameter in an amorphous carbon matrix, while NCT type II was a homogenous C : Ni film. Based on the Raman spectra of more than 600 individual SWCNTs, the diameter distribution obtained from both types of NCT was determined. SWCNTs with a selective, monomodal diameter distribution are obtained from NCT

  7. A wide spectral range single-photon avalanche diode fabricated in an advanced 180 nm CMOS technology.

    PubMed

    Mandai, Shingo; Fishburn, Matthew W; Maruyama, Yuki; Charbon, Edoardo

    2012-03-12

    We present a single-photon avalanche diode (SPAD) with a wide spectral range fabricated in an advanced 180 nm CMOS process. The realized SPAD achieves 20 % photon detection probability (PDP) for wavelengths ranging from 440 nm to 820 nm at an excess bias of 4 V, with 30 % PDP at wavelengths from 520 nm to 720 nm. Dark count rates (DCR) are at most 5 kHz, which is 30 Hz/μm2, at an excess bias of 4V when we measure 10 μm diameter active area structure. Afterpulsing probability, timing jitter, and temperature effects on DCR are also presented. PMID:22418462

  8. Catastrophes of large diameter pipelines. The role of hydrogen fields

    SciTech Connect

    Polyakov, V.N.

    1995-09-01

    Fracture statistics on transmission pipelines is presented. Fractures of large-diameter pipelines are regarded as catastrophes. Fracture accidents of other pipes are less dangerous. Hydrogen makes outer layers of pipes brittle. Therefore, critical crack lengths for pipes have been calculated by a linear fracture mechanics technique. It was found that a crack of any length may be critical. The opposite opinion on reliable operation of large-diameter pipes (diameter 1420 mm) is discussed.

  9. The investigation of the diameter dimension effect on the Si nano-tube transistors

    NASA Astrophysics Data System (ADS)

    Liao, M.-H.; Yeh, C.-H.; Lee, C.-C.; Wang, C.-P.

    2016-03-01

    The vertical gate-all-around (V-GAA) Si nano-tube (NT) devices with different diameter dimensions are studied in this work with the promising device performance. The V-GAA structure makes the transistor easy to be scaled down continuously to meet the complementary metal-oxide-semiconductor (CMOS) scaling requirements of the 7/10 nm technology node and beyond. The Si NT device with the hollow structure is demonstrated to have the capability to "deplete" and "screen-out" the out-of gate control carriers in the center of the NT and further result in the better device short channel control. Based on the study in this work, the V-GAA Si NT device with the optimized diameter dimension (=20 nm) can benefit the Ion-state current and reduce the Ioff-state stand-by power simultaneously, due to the less surface roughness scattering and the better short channel control characteristics. The proposed V-GAA Si NT device is regarded as one of the most promising candidates for the future application of the sub-7/10 nm logic era.

  10. Simultaneous three-wavelength continuous wave laser at 946 nm, 1319 nm and 1064 nm in Nd:YAG

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Zhao, Lianshui; Zhai, Pei; Xia, Jing; Fu, Xihong; Li, Shutao

    2013-01-01

    A continuous-wave (cw) diode-end-pumped Nd:YAG laser that generates simultaneous laser at the wavelengths 946 nm, 1319 nm and 1064 nm is demonstrated. The optimum oscillation condition for the simultaneous three-wavelength operation has been derived. Using the separation of the three output couplers, we obtained the maximum output powers of 0.24 W at 946 nm, 1.07 W at 1319 nm and 1.88 W at 1064 nm at the absorbed pump power of 11.2 W. A total output power of 3.19 W for the three-wavelength was achieved at the absorbed pump power of 11.2 W with optical conversion efficiency of 28.5%.

  11. Chromatin fibers are left-handed double helices with diameter and mass per unit length that depend on linker length.

    PubMed Central

    Williams, S P; Athey, B D; Muglia, L J; Schappe, R S; Gough, A H; Langmore, J P

    1986-01-01

    Four classes of models have been proposed for the internal structure of eukaryotic chromosome fibers--the solenoid, twisted-ribbon, crossed-linker, and superbead models. We have collected electron image and x-ray scattering data from nuclei, and isolated chromatin fibers of seven different tissues to distinguish between these models. The fiber diameters are related to the linker lengths by the equation: D(N) = 19.3 + 0.23 N, where D(N) is the external diameter (nm) and N is the linker length (base pairs). The number of nucleosomes per unit length of the fibers is also related to linker length. Detailed studies were done on the highly regular chromatin from erythrocytes of Necturus (mud puppy) and sperm of Thyone (sea cucumber). Necturus chromatin fibers (N = 48 bp) have diameters of 31 nm and have 7.5 +/- 1 nucleosomes per 10 nm along the axis. Thyone chromatin fibers (N = 87 bp) have diameters of 39 nm and have 12 +/- 2 nucleosomes per 10 nm along the axis. Fourier transforms of electron micrographs of Necturus fibers showed left-handed helical symmetry with a pitch of 25.8 +/- 0.8 nm and pitch angle of 32 +/- 3 degrees, consistent with a double helix. Comparable conclusions were drawn from the Thyone data. The data do not support the solenoid, twisted-ribbon, or supranucleosomal particle models. The data do support two crossed-linker models having left-handed double-helical symmetry and conserved nucleosome interactions. Images FIGURE 1 FIGURE 2 FIGURE 8 FIGURE 11 PMID:3955173

  12. Wire diameter dependence in the catalytic decomposition of H2

    NASA Astrophysics Data System (ADS)

    Umemoto, Hironobu

    2014-01-01

    Jansen et al. have demonstrated that the dissociaiton rate of H2 molecules on hot wire surfaces, normalized per unit surface area, depends on the wire diameter based on the electrical power consumption measurements [J. Appl. Phys. 66, 5749 (1989)]. Mathematical modeling calculations have also been presented to support their experimental results. In the present paper, it is shown that such a wire diameter dependence cannot be observed and that the H-atom density normalized by the wire surface area depends little on the wire diameter. Modeling calculations also show that the wire diameter dependence of the dissociation rate cannot be expected under typical decomposition conditions.

  13. Determination of the complex refractive index of a subwavelength-diameter platinum or gold pipe by light scattering.

    PubMed

    Tajima, Fumiaki; Nishiyama, Yoshio

    2016-09-01

    The complex refractive indices of Pt and Au pipes that are subwavelength in diameter have been found to be different from those of metal thin films for the first time. The metal pipe is made from a spider silk of half-wavelength diameter clad with Pt or Au and illuminated by a plane-polarized laser of wavelength 660 nm at normal incidence. The angular distribution of the light intensity scattered by the pipe is measured and fitted using theoretical calculations based on the corresponding model. The fitting results have lead to the optimum values and uncertainty ranges of the indices and the diameter of the pipe. A field emission scanning electron microscope confirms the diameter from the optical estimation and reveals an image of the surface of the pipe. PMID:27607485

  14. Fabricating vertically aligned sub-20 nm Si nanowire arrays by chemical etching and thermal oxidation

    NASA Astrophysics Data System (ADS)

    Li, Luping; Fang, Yin; Xu, Cheng; Zhao, Yang; Zang, Nanzhi; Jiang, Peng; Ziegler, Kirk J.

    2016-04-01

    Silicon nanowires (SiNWs) are appealing building blocks in various applications, including photovoltaics, photonics, and sensors. Fabricating SiNW arrays with diameters <100 nm remains challenging through conventional top-down approaches. In this work, chemical etching and thermal oxidation are combined to fabricate vertically aligned, sub-20 nm SiNW arrays. Defect-free SiNWs with diameters between 95 and 200 nm are first fabricated by nanosphere (NS) lithography and chemical etching. The key aspects for defect-free SiNW fabrication are identified as: (1) achieving a high etching selectivity during NS size reduction; (2) retaining the circular NS shape with smooth sidewalls; and (3) using a directional metal deposition technique. SiNWs with identical spacing but variable diameters are demonstrated by changing the reactive ion etching power. The diameter of the SiNWs is reduced by thermal oxidation, where self-limiting oxidation is encountered after oxidizing the SiNWs at 950 °C for 1 h. A second oxidation is performed to achieve vertically aligned, sub-20 nm SiNW arrays. Si/SiO2 core/shell NWs are obtained before removing the oxidized shell. HRTEM imaging shows that the SiNWs have excellent crystallinity.

  15. Ultrabreathable and Protective Membranes with Sub-5 nm Carbon Nanotube Pores.

    PubMed

    Bui, Ngoc; Meshot, Eric R; Kim, Sangil; Peña, José; Gibson, Phillip W; Wu, Kuang Jen; Fornasiero, Francesco

    2016-07-01

    Small-diameter carbon nanotubes (CNTs) are shown to enable exceptionally fast transport of water vapor under a concentration gradient driving force. Thanks to this property, membranes having sub-5 nm CNTs as conductive pores feature outstanding breathability while maintaining a high degree of protection from biothreats by size exclusion. PMID:27159328

  16. Fabricating vertically aligned sub-20 nm Si nanowire arrays by chemical etching and thermal oxidation.

    PubMed

    Li, Luping; Fang, Yin; Xu, Cheng; Zhao, Yang; Zang, Nanzhi; Jiang, Peng; Ziegler, Kirk J

    2016-04-22

    Silicon nanowires (SiNWs) are appealing building blocks in various applications, including photovoltaics, photonics, and sensors. Fabricating SiNW arrays with diameters <100 nm remains challenging through conventional top-down approaches. In this work, chemical etching and thermal oxidation are combined to fabricate vertically aligned, sub-20 nm SiNW arrays. Defect-free SiNWs with diameters between 95 and 200 nm are first fabricated by nanosphere (NS) lithography and chemical etching. The key aspects for defect-free SiNW fabrication are identified as: (1) achieving a high etching selectivity during NS size reduction; (2) retaining the circular NS shape with smooth sidewalls; and (3) using a directional metal deposition technique. SiNWs with identical spacing but variable diameters are demonstrated by changing the reactive ion etching power. The diameter of the SiNWs is reduced by thermal oxidation, where self-limiting oxidation is encountered after oxidizing the SiNWs at 950 °C for 1 h. A second oxidation is performed to achieve vertically aligned, sub-20 nm SiNW arrays. Si/SiO2 core/shell NWs are obtained before removing the oxidized shell. HRTEM imaging shows that the SiNWs have excellent crystallinity. PMID:26953775

  17. Ultrabreathable and protective membranes with sub-5 nm carbon nanotube pores

    DOE PAGESBeta

    Bui, Ngoc; Meshot, Eric R.; Kim, Sangil; Pena, Jose; Gibson, Phillip W.; Wu, Kuang Jen; Fornasiero, Francesco

    2016-05-09

    Here, small-diameter carbon nanotubes (CNTs) are shown to enable exceptionally fast transport of water vapor under a concentration gradient driving force. Thanks to this property, membranes having sub-5 nm CNTs as conductive pores feature outstanding breathability while maintaining a high degree of protection from biothreats by size exclusion.

  18. Stability of carbon nanotubes under electron irradiation: Role of tube diameter and chirality

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, A. V.; Banhart, F.; Li, J. X.; Foster, A. S.; Nieminen, R. M.

    2005-09-01

    As recent experiments demonstrate, the inner shells of multiwalled carbon nanotubes are more sensitive to electron irradiation than the outer shells. To understand the origin of such counterintuitive behavior, we employ a density-functional-theory based tight-binding method and calculate the displacement threshold energies for carbon atoms in single-walled nanotubes with different diameters and chiralities. We show that the displacement energy and the defect production rate strongly depend on the diameter of the nanotube and its chirality, with the displacement energy being lower, but saturating towards the value for graphite when the tube diameter increases. This implies that the threshold electron energies to produce damage in nanotubes with diameters smaller than 1nm are less than the commonly accepted value for graphitic nanoparticles. We also calculate the displacement energies for carbon atoms near defects and show that if a single vacancy is formed, it will likely be transformed to a double vacancy, as the nanotube atomic network with double vacancies has no energetically unfavorable undercoordinated atoms.

  19. Influence of hole diameter on the average size and quantity distribution of Si nanoparticles

    NASA Astrophysics Data System (ADS)

    Chu, Lizhi; Zong, Yu; Deng, Zechao; Ding, Xuecheng; Zhao, Hongdong; Wang, Yinglong

    2013-12-01

    The single crystalline Si target with high resistivity was ablated by a XeCl excimer laser (wavelength 308nm) in pure Ar gas under the ambient pressure of 10 Pa. The mask with a 1-10 mm diameter hole in the center was placed at a distance of 1.5 cm to the Si target. The Si nanocrystalline films were systemically deposited on a glass or single crystalline Si substrate placed behind the mask parallelly with a distance of 1.0 cm. The Raman and X-ray diffraction spectra indicate that the films were nanocrystalline. Scanning electron microscope images of the films showed that the diameter of the hole affected on the quantity and distributed range of Si nanoparticles on the substrate. It was obtained that the average size of Si nanoparticles decreasing with the diameter of the hole increasing, the quantity of Si nanoparticles was proportional to the power of 1.5 of the hole diameter. It is the nonlinear dynamic process to lead to the experimental result.

  20. Diameter-controlled and surface-modified Sb₂Se₃ nanowires and their photodetector performance.

    PubMed

    Choi, Donghyeuk; Jang, Yamujin; Lee, JeeHee; Jeong, Gyoung Hwa; Whang, Dongmok; Hwang, Sung Woo; Cho, Kyung-Sang; Kim, Sang-Wook

    2014-01-01

    Due to its direct and narrow band gap, high chemical stability, and high Seebeck coefficient (1800 μVK(-1)), antimony selenide (Sb2Se3) has many potential applications, such as in photovoltaic devices, thermoelectric devices, and solar cells. However, research on the Sb2Se3 materials has been limited by its low electrical conductivity in bulk state. To overcome this challenge, we suggest two kinds of nano-structured materials, namely, the diameter-controlled Sb2Se3 nanowires and Ag2Se-decorated Sb2Se3 nanowires. The photocurrent response of diameter-controlled Sb2Se3, which depends on electrical conductivity of the material, increases non-linearly with the diameter of the nanowire. The photosensitivity factor (K = I(light)/I(dark)) of the intrinsic Sb2Se3 nanowire with diameter of 80-100 nm is highly improved (K = 75). Additionally, the measurement was conducted using a single nanowire under low source-drain voltage. The dark- and photocurrent of the Ag2Se-decorated Sb2Se3 nanowire further increased, as compared to that of the intrinsic Sb2Se3 nanowire, to approximately 50 and 7 times, respectively. PMID:25336056

  1. Diameter-Controlled and Surface-Modified Sb2Se3 Nanowires and Their Photodetector Performance

    NASA Astrophysics Data System (ADS)

    Choi, Donghyeuk; Jang, Yamujin; Lee, Jeehee; Jeong, Gyoung Hwa; Whang, Dongmok; Hwang, Sung Woo; Cho, Kyung-Sang; Kim, Sang-Wook

    2014-10-01

    Due to its direct and narrow band gap, high chemical stability, and high Seebeck coefficient (1800 μVK-1), antimony selenide (Sb2Se3) has many potential applications, such as in photovoltaic devices, thermoelectric devices, and solar cells. However, research on the Sb2Se3 materials has been limited by its low electrical conductivity in bulk state. To overcome this challenge, we suggest two kinds of nano-structured materials, namely, the diameter-controlled Sb2Se3 nanowires and Ag2Se-decorated Sb2Se3 nanowires. The photocurrent response of diameter-controlled Sb2Se3, which depends on electrical conductivity of the material, increases non-linearly with the diameter of the nanowire. The photosensitivity factor (K = Ilight/Idark) of the intrinsic Sb2Se3 nanowire with diameter of 80-100 nm is highly improved (K = 75). Additionally, the measurement was conducted using a single nanowire under low source-drain voltage. The dark- and photocurrent of the Ag2Se-decorated Sb2Se3 nanowire further increased, as compared to that of the intrinsic Sb2Se3 nanowire, to approximately 50 and 7 times, respectively.

  2. Diameter-Controlled and Surface-Modified Sb2Se3 Nanowires and Their Photodetector Performance

    PubMed Central

    Choi, Donghyeuk; Jang, Yamujin; Lee, JeeHee; Jeong, Gyoung Hwa; Whang, Dongmok; Hwang, Sung Woo; Cho, Kyung-Sang; Kim, Sang-Wook

    2014-01-01

    Due to its direct and narrow band gap, high chemical stability, and high Seebeck coefficient (1800 μVK−1), antimony selenide (Sb2Se3) has many potential applications, such as in photovoltaic devices, thermoelectric devices, and solar cells. However, research on the Sb2Se3 materials has been limited by its low electrical conductivity in bulk state. To overcome this challenge, we suggest two kinds of nano-structured materials, namely, the diameter-controlled Sb2Se3 nanowires and Ag2Se-decorated Sb2Se3 nanowires. The photocurrent response of diameter-controlled Sb2Se3, which depends on electrical conductivity of the material, increases non-linearly with the diameter of the nanowire. The photosensitivity factor (K = Ilight/Idark) of the intrinsic Sb2Se3 nanowire with diameter of 80–100 nm is highly improved (K = 75). Additionally, the measurement was conducted using a single nanowire under low source-drain voltage. The dark- and photocurrent of the Ag2Se-decorated Sb2Se3 nanowire further increased, as compared to that of the intrinsic Sb2Se3 nanowire, to approximately 50 and 7 times, respectively. PMID:25336056

  3. Enhancement of conductivity by diameter control of polyimide-based electrospun carbon nanofibers.

    PubMed

    Xuyen, Nguyen Thi; Ra, Eun Ju; Geng, Hong-Zhang; Kim, Ki Kang; An, Kay Hyeok; Lee, Young Hee

    2007-10-01

    Oxydianiline-pyromellitic dianhydride poly(amic acid) (ODA-PMDA PAA) was polymerized with a catalyst support of triethyl amine for controlling molecular weight. This polymer was used for electrospinning in the preparation of PAA nanofibers, a precursor of carbon nanofibers. Here the amount of catalyst and concentration of PAA solution were optimized to produce polyimide-based carbon nanofibers approximately 80 nm in diameter. The effects of molecular weight of PAA, bias voltage, and spinning rate on the morphology of electrospun PAA and polyimide nanofibers have been evaluated. We showed that the conductivity of the carbon nanofiber mat decreased with increasing nanofiber diameter, where the conductivity of polyimide-based carbon nanofiber mat was much higher than those of other types of carbon nanofiber mat. The key ingredient to increase conductivity in a carbon nanofiber mat was found to be the number of cross junctions between nanofibers. PMID:17850139

  4. Probing Magnetic Susceptibility Anisotropy of Large-Diameter Armchair Carbon Nanotubes via Magnetic Linear Dichroism Spectroscopy

    NASA Astrophysics Data System (ADS)

    Haroz, Erik; Kono, Junichiro; Searles, Thomas; Tu, Xiaomin; Zheng, Ming; Fagan, Jeffrey; McGill, Stephen; Smirnov, Dmitry

    2012-02-01

    We studied magnetic susceptibility anisotropy, via magnetic linear dichroism spectroscopy, of aqueous suspensions of single-walled carbon nanotubes in high magnetic fields up to 22T using a unique magnet system (Split-Florida Helix magnet). Specifically, we measured magnetic susceptibility anisotropies, δχ, of several armchair species ranging from (5,5)-(13,13) at room temperature over an excitation wavelength range of 400-900 nm. For large diameter armchairs such as (12,12) and (13,13), we have observed some of the strongest alignment in a static magnetic field due to their large diameters. Results will be discussed in comparison with detailed calculations involving the Aharonov-Bohm effect.

  5. Brain Arterial Diameters as a Risk Factor for Vascular Events

    PubMed Central

    Gutierrez, Jose; Cheung, Ken; Bagci, Ahmet; Rundek, Tatjana; Alperin, Noam; Sacco, Ralph L; Wright, Clinton B; Elkind, Mitchell S V

    2015-01-01

    Background Arterial luminal diameters are routinely used to assess for vascular disease. Although small diameters are typically considered pathological, arterial dilatation has also been associated with disease. We hypothesize that extreme arterial diameters are biomarkers of the risk of vascular events. Methods and Results Participants in the Northern Manhattan Study who had a time-of-flight magnetic resonance angiography were included in this analysis (N=1034). A global arterial Z-score, called the brain arterial remodeling (BAR) score, was obtained by averaging the measured diameters within each individual. Individuals with a BAR score <−2 SDs were considered to have the smallest diameters, individuals with a BAR score >−2 and <2 SDs had average diameters, and individuals with a BAR score >2 SDs had the largest diameters. All vascular events were recorded prospectively after the brain magnetic resonance imaging. Spline curves and incidence rates were used to test our hypothesis. The association of the BAR score with death (P=0.001), vascular death (P=0.02), any vascular event (P=0.05), and myocardial infarction (P=0.10) was U-shaped except for ischemic stroke (P=0.74). Consequently, incidence rates for death, vascular death, myocardial infarction, and any vascular event were higher in individuals with the largest diameters, whereas individuals with the smallest diameters had a higher incidence of death, vascular death, any vascular event, and ischemic stroke compared with individuals with average diameters. Conclusions The risk of death, vascular death, and any vascular event increased at both extremes of brain arterial diameters. The pathophysiology linking brain arterial remodeling to systemic vascular events needs further research. PMID:26251284

  6. Composition of 15-80 nm particles in marine air

    NASA Astrophysics Data System (ADS)

    Lawler, M. J.; Whitehead, J.; O'Dowd, C.; Monahan, C.; McFiggans, G.; Smith, J. N.

    2014-01-01

    The chemical composition of 15-80 nm diameter particles was measured at Mace Head, Ireland, during May 2011 using the TDCIMS (Thermal Desorption Chemical Ionization Mass Spectrometer). Measurable levels of chloride, sodium, and sulfate were present in essentially all collected samples of these particles at this coastal Atlantic site. Organic compounds were rarely detectable, but this was likely an instrumental limitation. Concomitant particle hygroscopicity observations usually showed two main modes, one which contained a large sea salt component and another which was likely dominated by sulfate. There were several occasions lasting from hours to about two days during which 10-60 nm particle number increased dramatically in polar oceanic air. During these events, the sulfate mode increased substantially in number. This observation, along with the presence of very small (<10 nm) particles during the events, suggests that the particles were formed by homogeneous nucleation, followed by subsequent growth by sulfuric acid and potentially other vapors. The frequency of the events and similarity of event particles to background particles suggest that these events are important contributors of nanoparticles in this environment.

  7. Dataset for the validation and use of DiameterJ an open source nanofiber diameter measurement tool.

    PubMed

    Hotaling, Nathan A; Bharti, Kapil; Kriel, Haydn; Simon, Carl G

    2015-12-01

    DiameterJ is an open source image analysis plugin for ImageJ. DiameterJ produces ten files for every image that it analyzes. These files include the images that were analyzed, the data to create histograms of fiber radius, pore size, fiber orientation, and summary statistics, as well as images to check the output of DiameterJ. DiameterJ was validated with 130 in silico-derived, digital, synthetic images and 24 scanning electron microscope (SEM) images of steel wire samples with a known diameter distribution. Once validated, DiameterJ was used to analyze SEM images of electrospun polymeric nanofibers, including a comparison of different segmentation algorithms. In this article, all digital synthetic images, SEM images, and their segmentations are included. Additionally, DiameterJ's raw output files, and processed data is included for the reader. The data provided herein was used to generate the figures in DiameterJ: A Validated Open Source Nanofiber Diameter Measurement Tool[1], where more discussion can be found. PMID:26380840

  8. Dataset for the validation and use of DiameterJ an open source nanofiber diameter measurement tool

    PubMed Central

    Hotaling, Nathan A.; Bharti, Kapil; Kriel, Haydn; Simon, Carl G.

    2015-01-01

    DiameterJ is an open source image analysis plugin for ImageJ. DiameterJ produces ten files for every image that it analyzes. These files include the images that were analyzed, the data to create histograms of fiber radius, pore size, fiber orientation, and summary statistics, as well as images to check the output of DiameterJ. DiameterJ was validated with 130 in silico-derived, digital, synthetic images and 24 scanning electron microscope (SEM) images of steel wire samples with a known diameter distribution. Once validated, DiameterJ was used to analyze SEM images of electrospun polymeric nanofibers, including a comparison of different segmentation algorithms. In this article, all digital synthetic images, SEM images, and their segmentations are included. Additionally, DiameterJ’s raw output files, and processed data is included for the reader. The data provided herein was used to generate the figures in DiameterJ: A Validated Open Source Nanofiber Diameter Measurement Tool[1], where more discussion can be found. PMID:26380840

  9. The Measurements of the Solar Diameter at the Kepler's Times

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino; Fraschetti, Federico

    2002-12-01

    We examine five measurements of the solar disk diameter made with a pinhole instrument by Tycho in 1591 and Kepler in 1600-1602 [1]. Those are the first accurate measurements of the solar disk diameter available in literature, even if Ptolemy and Copernicus already did such measurements [2].

  10. Method accurately measures mean particle diameters of monodisperse polystyrene latexes

    NASA Technical Reports Server (NTRS)

    Kubitschek, H. E.

    1967-01-01

    Photomicrographic method determines mean particle diameters of monodisperse polystyrene latexes. Many diameters are measured simultaneously by measuring row lengths of particles in a triangular array at a glass-oil interface. The method provides size standards for electronic particle counters and prevents distortions, softening, and flattening.

  11. Periodically Diameter-Modulated Semiconductor Nanowires for Enhanced Optical Absorption.

    PubMed

    Ko, Minjee; Baek, Seong-Ho; Song, Bokyung; Kang, Jang-Won; Kim, Shin-Ae; Cho, Chang-Hee

    2016-04-01

    A diameter-modulated silicon nanowire array to enhance the optical absorption across broad spectral range is presented. Periodic shape engineering is achieved using conventional semiconductor processes and the unique optical properties are analyzed. The periodicity in the diameter of the silicon nanowires enables stronger and more closely spaced optical resonances, leading to broadband absorption enhancement. PMID:26833855

  12. Crystallization and fusion behaviors, observed by adiabatic calorimetry, of benzene confined in silica mesopores with uniform diameters.

    PubMed

    Nagoe, Atsushi; Oguni, Masaharu; Fujimori, Hiroki

    2015-03-18

    Heat capacities and spontaneous enthalpy-relaxation effects of the benzene confined in silica MCM-41 and SBA-15 pores with uniform diameters were measured by high-precision adiabatic calorimetry. The fusion temperatures and fusion enthalpies determined were compared with the literature results of benzene confined within pores of CPG glasses. It was confirmed, from the observed spontaneous heat-release or -absorption effects, that there exists a non-crystallizing amorphous component of confined benzene, as reported previously. The pore-diameter dependence of fusion enthalpy observed was inconsistent with the previously proposed model which suggested that the non-crystallizing amorphous component is located on the pore wall in the form of a shell-like structure of a few nm in thickness. A very slow relaxation process corresponding to a translational-diffusion motion of molecule was observed, indicating that the benzene fills the pores incompletely along the pore channel. In addition, we found that the fusion enthalpy as a function of inverse pore-diameter dependence decreases steeply in the range of 60-10 nm in diameter while gradually in the range around 5 nm. PMID:25627639

  13. Crystallization and fusion behaviors, observed by adiabatic calorimetry, of benzene confined in silica mesopores with uniform diameters

    NASA Astrophysics Data System (ADS)

    Nagoe, Atsushi; Oguni, Masaharu; Fujimori, Hiroki

    2015-03-01

    Heat capacities and spontaneous enthalpy-relaxation effects of the benzene confined in silica MCM-41 and SBA-15 pores with uniform diameters were measured by high-precision adiabatic calorimetry. The fusion temperatures and fusion enthalpies determined were compared with the literature results of benzene confined within pores of CPG glasses. It was confirmed, from the observed spontaneous heat-release or -absorption effects, that there exists a non-crystallizing amorphous component of confined benzene, as reported previously. The pore-diameter dependence of fusion enthalpy observed was inconsistent with the previously proposed model which suggested that the non-crystallizing amorphous component is located on the pore wall in the form of a shell-like structure of a few nm in thickness. A very slow relaxation process corresponding to a translational-diffusion motion of molecule was observed, indicating that the benzene fills the pores incompletely along the pore channel. In addition, we found that the fusion enthalpy as a function of inverse pore-diameter dependence decreases steeply in the range of 60-10 nm in diameter while gradually in the range around 5 nm.

  14. Uniform circular disks with synthetically tailorable diameters: two-dimensional nanoparticles for plasmonics.

    PubMed

    O'Brien, Matthew N; Jones, Matthew R; Kohlstedt, Kevin L; Schatz, George C; Mirkin, Chad A

    2015-02-11

    Herein, we report the synthesis of structurally uniform gold circular disks as two-dimensional plasmonic nanostructures that complement the well-established one-dimensional rod and three-dimensional shell structures. We show that a Au conproportionation reaction can be used to etch a collection of nonuniform triangular prisms into a uniform circular disk product with thickness and diameter varying <10%. These new particles have broadly tunable plasmon resonances (650-1000 nm) with narrow bandwidths (0.23-0.28 eV) and can be described as "effectively two-dimensional" plasmonic structures, as they do not support a significant transverse mode. PMID:25562383

  15. Reliable Diameter Control of Carbon Nanotube Nanobundles Using Withdrawal Velocity.

    PubMed

    Shin, Jung Hwal; Kim, Kanghyun; An, Taechang; Choi, WooSeok; Lim, Geunbae

    2016-12-01

    Carbon nanotube (CNT) nanobundles are widely used in nanoscale imaging, fabrication, and electrochemical and biological sensing. The diameter of CNT nanobundles should be controlled precisely, because it is an important factor in determining electrode performance. Here, we fabricated CNT nanobundles on tungsten tips using dielectrophoresis (DEP) force and controlled their diameters by varying the withdrawal velocity of the tungsten tips. Withdrawal velocity pulling away from the liquid-air interface could be an important, reliable parameter to control the diameter of CNT nanobundles. The withdrawal velocity was controlled automatically and precisely with a one-dimensional motorized stage. The effect of the withdrawal velocity on the diameter of CNT nanobundles was analyzed theoretically and compared with the experimental results. Based on the attachment efficiency, the withdrawal velocity is inversely proportional to the diameter of the CNT nanobundles; this has been demonstrated experimentally. Control of the withdrawal velocity will play an important role in fabricating CNT nanobundles using DEP phenomena. PMID:27581602

  16. Size dependent compressibility of nano-ceria: Minimum near 33 nm

    NASA Astrophysics Data System (ADS)

    Rodenbough, Philip P.; Song, Junhua; Walker, David; Clark, Simon M.; Kalkan, Bora; Chan, Siu-Wai

    2015-04-01

    We report the crystallite-size-dependency of the compressibility of nanoceria under hydrostatic pressure for a wide variety of crystallite diameters and comment on the size-based trends indicating an extremum near 33 nm. Uniform nano-crystals of ceria were synthesized by basic precipitation from cerium (III) nitrate. Size-control was achieved by adjusting mixing time and, for larger particles, a subsequent annealing temperature. The nano-crystals were characterized by transmission electron microscopy and standard ambient x-ray diffraction (XRD). Compressibility, or its reciprocal, bulk modulus, was measured with high-pressure XRD at LBL-ALS, using helium, neon, or argon as the pressure-transmitting medium for all samples. As crystallite size decreased below 100 nm, the bulk modulus first increased, and then decreased, achieving a maximum near a crystallite diameter of 33 nm. We review earlier work and examine several possible explanations for the peaking of bulk modulus at an intermediate crystallite size.

  17. Femoral head diameter considerations for primary total hip arthroplasty.

    PubMed

    Girard, J

    2015-02-01

    The configuration of total hip arthroplasty (THA) implants has constantly evolved since they were first introduced. One of the key components of THA design is the diameter of the prosthetic femoral head. It has been well established that the risk of dislocation is lower as the head diameter increases. But head diameter impacts other variables beyond joint stability: wear, cam-type impingement, range of motion, restoration of biomechanics, proprioception and groin pain. The introduction of highly cross-linked polyethylene and hard-on-hard bearings has allowed surgeons to implant large-diameter heads that almost completely eliminate the risk of dislocation. But as a result, cup liners have become thinner. With femoral head diameters up to 36 mm, the improvement in joint range of motion, delay in cam-type impingement and reduction in dislocation risk have been clearly demonstrated. Conversely, large-diameter heads do not provide any additional improvements. If an "ecologically sound" approach to hip replacement is embraced (e.g. keeping the native femoral head diameter), hip resurfacing with a metal-on-metal bearing must be carried out. The reliability of large-diameter femoral heads in the longer term is questionable. Large-diameter ceramic-on-ceramic bearings may be plagued by the same problems as metal-on-metal bearings: groin pain, squeaking, increased stiffness, irregular lubrication, acetabular loosening and notable friction at the Morse taper. These possibilities require us to be extra careful when using femoral heads with a diameter greater than 36 mm. PMID:25596984

  18. Pupil Diameter Changes in High Myopes after Collamer Lens Implantation

    PubMed Central

    Li, Dan; Yang, Yabo; Su, Caipei; Yin, Houfa; Liu, Xue

    2015-01-01

    ABSTRACT Purpose To observe the changes in pupil size under photopic and scotopic conditions after Implantable Collamer Lens (ICL) implantations in eyes with high myopia. Methods The ICL was implanted in 90 eyes belonging to 45 patients with high myopia. Photopic pupil diameters, scotopic pupil diameters, anterior chamber depths, and ICL vaults were examined at the preoperative, postoperative 1-month, and postoperative 3-month stages. The preoperative and postoperative photopic pupil diameters and scotopic pupil diameters were also compared with each other to note the differences between them. The correlations between preoperative and postoperative pupil diameter changes under different light conditions and presurgical refractive error were analyzed alongside patient’s age and ICL vault. Results Pupil diameters at both postoperative 1-month and postoperative 3-month stages were smaller than those before operation in distinct light environments, as well as pupil constriction amplitude. Correlation analysis showed that there was a statistically significant correlation between pupil diameter changes under different light conditions and presurgical refractive error at 1 month and 3 months after ICL implantation; pupil diameter decreased more when presurgical refractive error powers were less myopic. Statistically significant correlations were not found, however, with patient’s age and ICL vault. Postoperative 1-month and mean postoperative 3-month anterior chamber depths were decreased when compared with preoperative anterior chamber depths. Statistically significant correlations were found in change in preoperative and postoperative anterior chamber depth and ICL vault. No statistically significant difference was found between ICL vault at the postoperative 1-month and postoperative 3-month stages. Conclusions Pupil diameter may decrease at the 1- and 3-month stages after ICL implantation under both photopic and scotopic conditions. This indicates that reduction

  19. A multifunctional role of trialkylbenzenes for the preparation of aqueous colloidal mesostructured/mesoporous silica nanoparticles with controlled pore size, particle diameter, and morphology

    NASA Astrophysics Data System (ADS)

    Yamada, Hironori; Ujiie, Hiroto; Urata, Chihiro; Yamamoto, Eisuke; Yamauchi, Yusuke; Kuroda, Kazuyuki

    2015-11-01

    Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size and higher hydrophobicity of TIPB than TMB induce the incorporation of TIPB into micelles without the structural change. When TMB was used as TAB, the pore size of CMSS was also enlarged while the mesostructure and particle morphology were varied. Interestingly, when tetramethoxysilane and TIPB were used, CMSS with a very small particle diameter (20 nm) with concave surfaces and large mesopores were obtained, which may strongly be related to the initial nucleation of CMSS. A judicious choice of TAB and Si sources is quite important to control the mesostructure, size of mesopores, particle diameter, and morphology.Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size

  20. Mass transport through vertically aligned large diameter MWCNTs embedded in parylene

    NASA Astrophysics Data System (ADS)

    Krishnakumar, P.; Tiwari, P. B.; Staples, S.; Luo, T.; Darici, Y.; He, J.; Lindsay, S. M.

    2012-11-01

    We have fabricated porous membranes using a parylene encapsulated vertically aligned forest of multi-walled carbon nanotubes (MWCNTs, about 7 nm inner diameter). The transport of charged particles in electrolyte through these membranes was studied by applying electric field and pressure. Under an electric field in the range of 4.4 × 104 V m-1, electrophoresis instead of electroomosis is found to be the main mechanism for ion transport. Small molecules and 5 nm gold nanoparticles can be driven through the membranes by an electric field. However, small biomolecules, like DNA oligomers, cannot. Due to the weak electric driving force, the interactions between charged particles and the hydrophobic CNT inner surface play important roles in the transport, leading to enhanced selectivity for small molecules. Simple chemical modification on the CNT ends also induces an obvious effect on the translocation of single strand DNA oligomers and gold nanoparticles under a modest pressure (<294 Pa).

  1. Mass transport through vertically aligned large diameter MWCNT embedded in parylene

    PubMed Central

    Krishnakumar, P; Tiwari, P B; Staples, S; Luo, T; Darici, Y; He, J; Lindsay, SM

    2013-01-01

    We have fabricated porous membranes using a parylene encapsulated vertically aligned forest of multi-walled carbon nanotube (MWCNT, about 7nm inner diameter). The transport of charged particles in electrolyte through these membranes was studied by applying electric field and pressure. Under an electric field in the range of 4.4×104 V/m, electrophoresis instead of electroomosis is found to be the main mechanism for ion transport. Small molecules and 5 nm gold nanoparticles can be driven through the membranes by an electric field. However, small biomolecules, like DNA oligomers, cannot. Due to the weak electric driving force, the interactions between charged particles and the hydrophobic CNT inner surface play important roles in the transport, leading to enhanced selectivity for small molecules. Simple chemical modification on the CNT ends also induces an obvious effect on the translocation of single strand DNA oligomer and gold nanoparticle under a modest pressure (<294 Pa). PMID:23064678

  2. Dielectric properties of polymer composites with carbon nanotubes of different diameters.

    PubMed

    Macutkevic, Jan; Paddubskaya, Alesia; Kuzhir, Polina; Banys, Juras; Maksimenko, Sergey; Kuznetsov, Vladimir L; Mazov, Ilya N; Krasnikov, Dmitrij V

    2014-07-01

    The dielectric properties of Polymethylmetacrylate (PMMA) composites filled with CVD made multiwalled carbon nanotubes (MWCNT) of different mean outer diameters (d - 9 nm and 12-14 nm) were investigated at temperatures from 300 K to 390 K and in a wide frequency range (20 Hz-1 MHz). The percolation threshold is lower in composites with thick nanotubes. Below percolation threshold the dielectric permittivity was found also to be higher for composites with thicker carbon nanotubes. The temperature dependence of the complex dielectric permittivity of the investigated composites below percolation is mainly caused by beta relaxation in pure PMMA polymer matrix. The potential barrier for PMMA molecules rotation is higher in composites with thicker MWCNT and demonstrates non-monotonous concentration dependence. PMID:24758044

  3. Binding of human coronary artery endothelial cells to plasma-treated titanium dioxide nanotubes of different diameters.

    PubMed

    Flašker, Ajda; Kulkarni, Mukta; Mrak-Poljšak, Katjuša; Junkar, Ita; Čučnik, Saša; Žigon, Polona; Mazare, Anca; Schmuki, Patrik; Iglič, Aleš; Sodin-Semrl, Snezna

    2016-05-01

    Nanoscale topography in improving vascular response in vitro was established previously on various titanium surfaces. In the present study different surface nanotopographies that is different diameters of titanium dioxide (TiO2 ) nanotubes (NTs) were fabricated by electrochemical anodization and conditioned with highly reactive gaseous oxygen plasma. The morphology of different diameter NTs was studied by scanning electron microscopy and atomic force microscopy, while changes in chemical composition on the surface before and after plasma treatment were determined by X-ray photoelectron spectroscopy. Performance of human coronary artery endothelial cells (HCAEC) on those conditioned surfaces was studied in regard to cell proliferation, released IL-6 protein and immunofluorescence microscopy (IFM). We show that HCAEC function is dependent on the diameter of the TiO2 NTs, functioning far less optimally when bound to 100 nm TiO2 NTs as compared to Ti foil, 15 nm NTs or 50 nm NTs. There were improved, morphological cell shape changes, observed with IFM, between HCAEC growing on oxygen-rich plasma-treated versus nontreated 100 nm NTs. These endothelialized conditioned Ti nanosurfaces could elucidate optimization conditions necessary for vascular implants in coronary arteries. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1113-1120, 2016. PMID:26748552

  4. Pore diameter effects on phase behavior of a gas condensate in graphitic one-and two-dimensional nanopores.

    PubMed

    Welch, William R W; Piri, Mohammad

    2016-01-01

    Molecular dynamics (MD) simulations were performed on a hydrocarbon mixture representing a typical gas condensate composed mostly of methane and other small molecules with small fractions of heavier hydrocarbons, representative of mixtures found in tight shale reservoirs. The fluid was examined both in bulk and confined to graphitic nano-scale slits and pores. Numerous widths and diameters of slits and pores respectively were examined under variable pressures at 300 K in order to find conditions in which the fluid at the center of the apertures would not be affected by capillary condensation due to the oil-wet walls. For the bulk fluid, retrograde phase behavior was verified by liquid volumes obtained from Voronoi tessellations. In cases of both one and two-dimensional confinement, for the smallest apertures, heavy molecules aggregated inside the pore space and compression of the gas outside the solid structure lead to decreases in density of the confined fluid. Normal density/pressure relationships were observed for slits having gaps of above 3 nm and pores having diameters above 6 nm. At 70 bar, the minimum gap width at which the fluid could pass through the center of slits without condensation effects was predicted to be 6 nm and the corresponding diameter in pores was predicted to be 8 nm. The models suggest that in nanoscale networks involving pores smaller than these limiting dimensions, capillary condensation should significantly impede transmission of natural gases with similar composition. PMID:26733485

  5. Effect of diameter of nanoparticles and capture cross-section library on macroscopic dose enhancement in boron neutron capture therapy

    PubMed Central

    Farhood, Bagher

    2014-01-01

    Purpose The aim of this study is evaluation of the effect of diameter of 10B nanoparticles and various neutron capture cross-section libraries on macroscopic dose enhancement in boron neutron capture therapy (BNCT). Material and methods MCNPX Monte Carlo code was used for simulation of a 252Cf source, a soft tissue phantom and a tumor containing 10B nanoparticles. Using 252Cf as a neutron source, macroscopic dose enhancement factor (MDEF) and total dose rate in tumor in the presence of 100, 200, and 500 ppm of 10B nanoparticles with 25 nm, 50 nm, and 100 nm diameters were calculated. Additionally, the effect of ENDF, JEFF, JENDL, and CENDL neutron capture cross-section libraries on MDEF was evaluated. Results There is not a linear relationship between the average MDEF value and nanoparticles’ diameter but the average MDEF grows with increased concentration of 10B nanoparticles. There is an increasing trend for average MDEF with the tumor distance. The average MDEF values were obtained the same for various neutron capture cross-section libraries. The maximum and minimum doses that effect on the total dose in tumor were neutron and secondary photon doses, respectively. Furthermore, the boron capture related dose component reduced in some extent with increase of diameter of 10B nanoparticles. Conclusions Based on the results of this study, it can be concluded that from physical point of view, various nanoparticle diameters have no dominant effect on average MDEF value in tumor. Furthermore, it is concluded that various neutron capture cross-section libraries are resulted to the same macroscopic dose enhancements. However, it is predicted that taking into account the biological effects for various nanoparticle diameters will result in different dose enhancements. PMID:25834582

  6. Size and time-resolved growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei

    NASA Astrophysics Data System (ADS)

    Kuang, C.; Chen, M.; Zhao, J.; Smith, J.; McMurry, P. H.; Wang, J.

    2012-04-01

    This study presents measurements of size and time-resolved particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Novel data analysis methods were developed, de-coupling for the first time the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated total aerosol (neutral and charged) were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the particle detector. One new particle formation (NPF) event from each campaign was analyzed in detail. At a given instant in time during the NPF event, size-resolved growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with particle size from ~1 to 3 nm geometric diameter, increasing from 5.5 ± 0.8 to 7.6 ± 0.6 nm h-1 in Atlanta (13:00) and from 5.6 ± 2 to 27 ± 5 nm h-1 in Boulder (13:00). The resulting growth rate enhancement Γ, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from ~1 to 3 nm geometric diameter. For the presented NPF events, values for Γ had lower limits that approached ~1 at 1.2 nm geometric diameter in Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and had upper limits that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Nucleated particle survival probability calculations comparing the effects of constant and size-dependent growth indicate that neglecting the strong dependence of growth rate on size from 1 to 3 nm observed in this study could lead to a significant overestimation of CCN survival

  7. Size and time-resolved growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei

    SciTech Connect

    Kuang C.; Chen, M.; Zhao, J.; Smith, J.; McMurry, P. H.; Wang, J.

    2012-04-12

    This study presents measurements of size and time-resolved particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Novel data analysis methods were developed, de-coupling for the first time the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated total aerosol (neutral and charged) were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the particle detector. One new particle formation (NPF) event from each campaign was analyzed in detail. At a given instant in time during the NPF event, size-resolved growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with particle size from {approx}1 to 3 nm geometric diameter, increasing from 5.5 {+-} 0.8 to 7.6 {+-} 0.6 nm h{sup -1} in Atlanta (13:00) and from 5.6 {+-} 2 to 27 {+-} 5 nm h{sup -1} in Boulder (13:00). The resulting growth rate enhancement {Lambda}, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from {approx}1 to 3 nm geometric diameter. For the presented NPF events, values for {Lambda} had lower limits that approached {approx}1 at 1.2 nm geometric diameter in Atlanta and {approx}3 at 0.8 nm geometric diameter in Boulder, and had upper limits that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Nucleated particle survival probability calculations comparing the effects of constant and size-dependent growth indicate that neglecting the strong dependence of growth rate on size from 1 to 3 nm observed in this study

  8. Binding of plasma proteins to titanium dioxide nanotubes with different diameters.

    PubMed

    Kulkarni, Mukta; Flašker, Ajda; Lokar, Maruša; Mrak-Poljšak, Katjuša; Mazare, Anca; Artenjak, Andrej; Čučnik, Saša; Kralj, Slavko; Velikonja, Aljaž; Schmuki, Patrik; Kralj-Iglič, Veronika; Sodin-Semrl, Snezna; Iglič, Aleš

    2015-01-01

    Titanium and titanium alloys are considered to be one of the most applicable materials in medical devices because of their suitable properties, most importantly high corrosion resistance and the specific combination of strength with biocompatibility. In order to improve the biocompatibility of titanium surfaces, the current report initially focuses on specifying the topography of titanium dioxide (TiO2) nanotubes (NTs) by electrochemical anodization. The zeta potential (ζ-potential) of NTs showed a negative value and confirmed the agreement between the measured and theoretically predicted dependence of ζ-potential on salt concentration, whereby the absolute value of ζ-potential diminished with increasing salt concentrations. We investigated binding of various plasma proteins with different sizes and charges using the bicinchoninic acid assay and immunofluorescence microscopy. Results showed effective and comparatively higher protein binding to NTs with 100 nm diameters (compared to 50 or 15 nm). We also showed a dose-dependent effect of serum amyloid A protein binding to NTs. These results and theoretical calculations of total available surface area for binding of proteins indicate that the largest surface area (also considering the NT lengths) is available for 100 nm NTs, with decreasing surface area for 50 and 15 nm NTs. These current investigations will have an impact on increasing the binding ability of biomedical devices in the body leading to increased durability of biomedical devices. PMID:25733829

  9. Binding of plasma proteins to titanium dioxide nanotubes with different diameters

    PubMed Central

    Kulkarni, Mukta; Flašker, Ajda; Lokar, Maruša; Mrak-Poljšak, Katjuša; Mazare, Anca; Artenjak, Andrej; Čučnik, Saša; Kralj, Slavko; Velikonja, Aljaž; Schmuki, Patrik; Kralj-Iglič, Veronika; Sodin-Semrl, Snezna; Iglič, Aleš

    2015-01-01

    Titanium and titanium alloys are considered to be one of the most applicable materials in medical devices because of their suitable properties, most importantly high corrosion resistance and the specific combination of strength with biocompatibility. In order to improve the biocompatibility of titanium surfaces, the current report initially focuses on specifying the topography of titanium dioxide (TiO2) nanotubes (NTs) by electrochemical anodization. The zeta potential (ζ-potential) of NTs showed a negative value and confirmed the agreement between the measured and theoretically predicted dependence of ζ-potential on salt concentration, whereby the absolute value of ζ-potential diminished with increasing salt concentrations. We investigated binding of various plasma proteins with different sizes and charges using the bicinchoninic acid assay and immunofluorescence microscopy. Results showed effective and comparatively higher protein binding to NTs with 100 nm diameters (compared to 50 or 15 nm). We also showed a dose-dependent effect of serum amyloid A protein binding to NTs. These results and theoretical calculations of total available surface area for binding of proteins indicate that the largest surface area (also considering the NT lengths) is available for 100 nm NTs, with decreasing surface area for 50 and 15 nm NTs. These current investigations will have an impact on increasing the binding ability of biomedical devices in the body leading to increased durability of biomedical devices. PMID:25733829

  10. Measuring helium bubble diameter distributions in tungsten with grazing incidence small angle x-ray scattering (GISAXS)

    NASA Astrophysics Data System (ADS)

    Thompson, M.; Kluth, P.; Doerner, R. P.; Kirby, N.; Riley, D.; Corr, C. S.

    2016-02-01

    Grazing incidence small angle x-ray scattering was performed on tungsten samples exposed to helium plasma in the MAGPIE and Pisces-A linear plasma devices to measure the size distributions of resulting helium nano-bubbles. Nano-bubbles were fitted assuming spheroidal particles and an exponential diameter distribution. These particles had mean diameters between 0.36 and 0.62 nm. Pisces-A exposed samples showed more complex patterns, which may suggest the formation of faceted nano-bubbles or nano-scale surface structures.

  11. Sterilization of various diameter dead-ended tubes.

    PubMed

    Young, J H

    1993-06-01

    Effect of tube diameter on steam-in-place sterilization of dead-ended tubes was studied by examining temperature profiles and rates of kill of Bacillus stearothermophilus spores. Time required for sterilization was determined for 9.4-cm-long tubes with various inside diameters from 0.4 to 1.7 cm. Sterilization time increased with decreasing tube diameter. Experimentally measured kill kinetics in 1.7-cm tubes were in agreement with those predicted if measured temperatures represented saturated steam. A 12-log spore reduction was achieved in 1.7-cm diameter vertical and horizontal tubes in less than 63 minutes. For smaller diameter tubes, entrapped air remained after 2 hours and rates of kill were very dependent on position within the tube, tube diameter, and tube orientation with respect to the gravitational vector. Times to achieve a 1-log drop in spore population in the smaller tubes were as much as 10 times greater than those expected if measured temperatures represented saturated steam. Sterilization was not achieved throughout the 0.4-cm tubes. Recommendations are made for including steam bleeders or using prevaccum cycles for these smaller diameter tubes. PMID:18609656

  12. Effects of diameter and temperature on XTX-8004 detonation velocity

    SciTech Connect

    Campos, C.A.

    1980-10-01

    This study was performed to determine the dependence of XTX-8004 steady detonation velocity on charge diameter and temperature. The tests were performed for four different diameters at three temperatures using a standard 4-track detonation velocity block and corresponding printed circuit ionization switch plate. The explosive was loaded in the detonation velocity block to a nominal density of 1.553 g/cc. Measurements obtained from two samples per temperature indicate the critical diameter is less than 0.178 cm. A relationship between detonation velocity and density due to temperature was established using experimental measurements.

  13. Calibration of the radiometric asteroid scale using occultation diameters

    NASA Technical Reports Server (NTRS)

    Telesco, C. M.; Brunk, W. E.; Brown, R. H.; Morrison, D.

    1982-01-01

    The paper describes a new approach to the calibration of the radiometric asteroid scale, which relies on recent accurate occultation measurements of the diameters of 2 Pallas (Wasserman et al., 1979) and 3 Juno (Millis et al., 1981), and the Voyager diameter of J4 Callisto, as well as IR photometry of these objects obtained with the NASA 3-m Infrared Telescope Facility. It is shown that this calibration is internally consistent to better than 5%, and probably has an absolute accuracy of + or - 5%. It is noted that a revision of the TRIAD radiometric diameters downward is required to bring them into agreement with the new calibration.

  14. Thermal mechanical analyses of large diameter ion accelerator systems

    SciTech Connect

    Brophy, J.R.; Aston, G.

    1989-01-01

    Thermal mechanical analyses of large diameter ion accelerator systems are performed using commercially available finite element software executed on a desktop computer. Finite element models of a 30-cm-diameter accelerator system formulated using plate/shell elements give calculated results which agree well with similar published obtained on a mainframe computer. Analyses of a 50-cm-diameter, three-grid accelerator system using measured grid temperatures (corresponding to discharge powers of 653 and 886 watts) indicate that thermally induced grid movements need not be the performance limiting phenomena for accelerator systems of this size. 8 refs.

  15. Thermal mechanical analyses of large diameter ion accelerator systems

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    Thermal mechanical analyses of large diameter ion accelerator systems are performed using commercially available finite element software executed on a desktop computer. Finite element models of a 30-cm-diameter accelerator system formulated using plate/shell elements give calculated results which agree well with similar published obtained on a mainframe computer. Analyses of a 50-cm-diameter, three-grid accelerator system using measured grid temperatures (corresponding to discharge powers of 653 and 886 watts) indicate that thermally induced grid movements need not be the performance limiting phenomena for accelerator systems of this size.

  16. Simultaneous triple 914 nm, 1084 nm, and 1086 nm operation of a diode-pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Xia, Jing; Liu, Huilong; Pu, Xiaoyun

    2014-10-01

    We report a diode-pumped continuous-wave (cw) triple-wavelength Nd:YVO4 laser operating at 914, 1084, and 1086 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous triple-wavelength laser. Using a T-shaped cavity, we realized an efficient triple-wavelength operation at 4F3/2→4I9/2 and 4F3/2→4I11/2 transitions for Nd:YVO4 crystal, simultaneously. At an absorbed pump power of 16 W (or 25 W of incident pump power), the maximum output power was 2.3 W, which included 914 nm, 1084 nm, and 1086 nm three wavelengths, and the optical conversion efficiency with respect to the absorbed pump power was 14.4%.

  17. Comparison of Failure Thickness and Critical Diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.

    2005-07-01

    The critical diameter and failure thickness of liquid nitromethane confined by aluminum are determined experimentally. A comparison of these two parameters provides insight into the failure mechanism in nitromethane. If the failure of detonation in a critical charge diameter (or thickness) experiment is due to reaction quenching resulting from wave curvature, then it is expected that the critical diameter should be half the value of the critical thickness.[1] This has been shown to be the case with gas-phase detonations with nearly laminar reaction zones.[2] By comparing the experimentally determined values of critical diameter and thickness for a homogeneous liquid explosive, the validity of this model of detonation failure can be assessed. References: 1. Ramsay, J.B., 8th Symp. (Int.) on Detonation., 372-379 (1985). 2. Radulescu, M., Lee, J.H.S., Comb. and Flame, 131:29-46 (2002).

  18. SMALL DIAMETER STENCILING, ROLLING OVER STAMP. United States Pipe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER STENCILING, ROLLING OVER STAMP. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  19. Wavelength dependence of the apparent diameter of retinal blood vessels.

    PubMed

    Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

    2005-04-01

    Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column. PMID:15813519

  20. Optimal electrode diameter in relation to volume of the cochlea.

    PubMed

    Gnansia, D; Demarcy, T; Vandersteen, C; Raffaelli, C; Guevara, N; Delingette, H; Ayache, N

    2016-06-01

    The volume of the cochlea is a key parameter for electrode-array design. Indeed, it constrains the diameter of the electrode-array for low-traumatic positioning in the scala timpani. The present report shows a model of scala timpani volume extraction from temporal bones images in order to estimate a maximum diameter of an electrode-array. Nine temporal bones were used, and passed to high-resolution computed tomography scan. Using image-processing techniques, scala timpani were extracted from images, and cross-section areas were estimated along cochlear turns. Cochlear implant electrode-array was fitted in these cross-sections. Results show that the electrode-array diameter is small enough to fit in the scala timpani, however the diameter is restricted at the apical part. PMID:27246746

  1. Anomalous dependence of band gaps of binary nanotubes on diameters

    NASA Astrophysics Data System (ADS)

    Adhikari, Kapil; Huda, Muhammad; Ray, Asok

    2012-02-01

    Using cluster approximation, AlN, BN, GaN, SiGe, SiC, and GeC armchair type 1 nanotubes have been spin optimized using the hybrid functional B3LYP, a double ζ basis set and the GAUSSIAN 03 software. The electronic structures of group III nitride and group IV-IV nanotubes indicate that the band gap increases with tube diameter contrary to behavior expected from quantum size effects. A detailed study indicates that, in a class of binary nanotubes with partial ionic contributions in the bonds, for example, AlN, BN, GaN, GeC, and SiC, ionicity of the bonds decreases as diameter decreases due to increased sp^3 contribution. This causes the band gap to increase with diameter. But in nanotubes with covalent bonding, for example SiGe, the gap decreases with diameter. A general trend for a class of binary nanotubes is established.

  2. SMALL DIAMETER GRAVITY SEWERS: AN ALTERNATIVE FOR UNSEWERED COMMUNITIES

    EPA Science Inventory

    The most recently introduced wastewater collection alternative for small unsewered communities is septic tank effluent drains or small diameter gravity sewers (SDGS). Unlike conventional sewers, SDGS only collect settled wastewater. Grit, grease and other troublesome solids which...

  3. SMALL DIAMETER CEMENT LINING FROM STAIRWAY. United States Pipe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER CEMENT LINING FROM STAIRWAY. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  4. SMALL DIAMETER PRECEMENT LINING FROM CATWALK ABOVE. United States ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER PRE-CEMENT LINING FROM CATWALK ABOVE. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  5. Northern view of inside diameter welding station of the saw ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Northern view of inside diameter welding station of the saw line in bay9 of the main pipe mill building. - U.S. Steel National Tube Works, Main Pipe Mill Building, Along Monongahela River, McKeesport, Allegheny County, PA

  6. Pupil diameter reflects uncertainty in attentional selection during visual search

    PubMed Central

    Geng, Joy J.; Blumenfeld, Zachary; Tyson, Terence L.; Minzenberg, Michael J.

    2015-01-01

    Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones and Cohen, 2005; Yu and Dayan, 2005). In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time (RT) and performance accuracy (Experiments 1-2). Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes. PMID:26300759

  7. SMALL DIAMETER PAINTING FROM CATWALK ABOVE. United States Pipe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER PAINTING FROM CATWALK ABOVE. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  8. Development of welded metal bellows having minimum effective diameter change

    NASA Technical Reports Server (NTRS)

    Henschel, J. K.; Stevens, J. B.; Harvey, A. C.; Howland, J. S.; Rhee, S. S.

    1972-01-01

    A program of analysis, design, and fabrication was conducted to develop welded metal bellows having a minimum change in effective diameter for cryogenic turbomachinery face seal applications. Linear analysis of the principle types of bellows provided identification of concepts capable of meeting basic operation requirements. For the 6-inch (.152 m) mean diameter, 1.5-inch free length bellows studied, nonlinear analysis showed that opposed and nested toroidal bellows plates stiffened by means of alternating stiffener rings were capable of maintaining constant effective diameter within 0.3% and 0.1% respectively under the operating conditions of interest. Changes in effective diameter were due principally to bellows axial deflection with pressure differential having a lesser influence. Fabrication problems associated with joining the thin bellows plates to the relatively heavy stiffener rings were encountered and precluded assembly and testing of a bellows core. Fabrication problems are summarized and recommended fabrication methods for future effort are presented.

  9. Eddy sensors for small diameter stainless steel tubes.

    SciTech Connect

    Skinner, Jack L.; Morales, Alfredo Martin; Grant, J. Brian; Korellis, Henry James; LaFord, Marianne Elizabeth; Van Blarigan, Benjamin; Andersen, Lisa E.

    2011-08-01

    The goal of this project was to develop non-destructive, minimally disruptive eddy sensors to inspect small diameter stainless steel metal tubes. Modifications to Sandia's Emphasis/EIGER code allowed for the modeling of eddy current bobbin sensors near or around 1/8-inch outer diameter stainless steel tubing. Modeling results indicated that an eddy sensor based on a single axial coil could effectively detect changes in the inner diameter of a stainless steel tubing. Based on the modeling results, sensor coils capable of detecting small changes in the inner diameter of a stainless steel tube were designed, built and tested. The observed sensor response agreed with the results of the modeling and with eddy sensor theory. A separate limited distribution SAND report is being issued demonstrating the application of this sensor.

  10. CMOS downsizing toward sub-10 nm

    NASA Astrophysics Data System (ADS)

    Iwai, Hiroshi

    2004-04-01

    Recently, CMOS downsizing has been accelerated very aggressively in both production and research level, and even transistor operation of a 6 nm gate length p-channel MOSFET was reported in a conference. However, many serious problems are expected for implementing such small-geometry MOSFETs into large scale integrated circuits, and it is still questionable whether we can successfully introduce sub-10 nm CMOS LSIs into the market or not. In this paper, limitation and its possible causes for the downscaling of CMOS towards sub-10 nm are discussed with consideration of past CMOS predictions for the limitation.

  11. Characterization of Detonation Wave Propagation in LX-17 Near the Critical Diameter

    SciTech Connect

    Tran, T D; Tarver, C M; Maienschein, J; Lewis, P; Pastrone, R; Lee, R S; Roeske, F

    2002-06-14

    A new Detonation Profile Test (DPT) was developed to measure simultaneously the detonation wave breakout profile and the average detonation velocity at the breakout surface. The test evaluated small cylindrical samples with diameter up to 19.08 mm and length up to 33 mm. The experiment involved initiating a LX-17 cylindrical specimen and recording the wave breakout using a fast streaking electronic camera. The initiation was done using a PBX-9407 pellet (1.630 g/cm{sup 3}), which has a Chapman-Jouguet (C-J) pressure close to that of LX-17. The acceptor breakout surface had a 2 mm wide by 1 mm deep groove that provided a step in the recorded breakout profile for velocity determination. A 532-nm laser light illuminated the specimen surface. A streak camera looking perpendicular to the groove, recorded the extinction of the laser light as the detonation wave emerged from the surface. This technique provided a high-resolution spatial and temporal profile of the wave curvature as well as accurate timing of the propagating wave over the last millimeter of the sample. The measured groove depth and recorded travel time were then used to calculate the average detonation wave velocity. Results for 12.7 mm diameter unconfined LX-17 charges showed detonation velocity in the range between 6.79 and 7.06 km/s for parts up to 33 mm long. Since LX-17 can not sustain detonation at less than 7.3 km/s , these waves were definitely failing. Experiments with confined 12.7 mm diameter and unconfined 19.1 mm diameter samples showed wave velocities in the range of 7.4-7.6 km/s, values approaching steady state conditions at infinite diameter. Both unconfined and confined charges show no sensitivity to density variations in the range between 1.890-1.915 g/cm{sup 3}. Experiments with 15.88 mm and 19.08 mm diameters gave velocities in the range between 7.2-7.45 km/s, values close to that expected for failure. The velocity measurement has an estimated experimental error in the range of 2

  12. Laser Damage Growth in Fused Silica with Simultaneous 351 nm and 1053 nm irradiation

    SciTech Connect

    Norton, M A; Carr, A V; Carr, C W; Donohue, E E; Feit, M D; Hollingsworth, W G; Liao, Z; Negres, R A; Rubenchik, A M; Wegner, P J

    2008-10-24

    Laser-induced growth of optical damage often determines the useful lifetime of an optic in a high power laser system. We have extended our previous work on growth of laser damage in fused silica with simultaneous 351 nm and 1053 nm laser irradiation by measuring the threshold for growth with various ratios of 351 nm and 1053 nm fluence. Previously we reported that when growth occurs, the growth rate is determined by the total fluence. We now find that the threshold for growth is dependent on both the magnitude of the 351 nm fluence as well as the ratio of the 351 nm fluence to the 1053 nm fluence. Furthermore, the data suggests that under certain conditions the 1053 nm fluence does not contribute to the growth.

  13. Acoustic fill factors for a 120 inch diameter fairing

    NASA Technical Reports Server (NTRS)

    Lee, Y. Albert

    1992-01-01

    Data from the acoustic test of a 120-inch diameter payload fairing were collected and an analysis of acoustic fill factors were performed. Correction factors for obtaining a weighted spatial average of the interior sound pressure level (SPL) were derived based on this database and a normalized 200-inch diameter fairing database. The weighted fill factors were determined and compared with statistical energy analysis (VAPEPS code) derived fill factors. The comparison is found to be reasonable.

  14. Thermal resistance of ultra-small-diameter disk microlasers

    SciTech Connect

    Zhukov, A. E. Kryzhanovskaya, N. V.; Maximov, M. V.; Lipovskii, A. A.; Savelyev, A. V.; Shostak, I. I.; Moiseev, E. I.; Kudashova, Yu. V.; Kulagina, M. M.; Troshkov, S. I.

    2015-05-15

    The thermal resistance of AlGaAs/GaAs microlasers of the suspended-disk type with a diameter of 1.7–4 μm and InAs/InGaAs quantum dots in the active region is inversely proportional to the squared diameter of the microdisk. The proportionality factor is 3.2 × 10{sup −3} (K cm{sup 2})/W, and the thermal resistance is 120–20°C/mW.

  15. Understanding the effect of carbon status on stem diameter variations

    PubMed Central

    De Swaef, Tom; Driever, Steven M.; Van Meulebroek, Lieven; Vanhaecke, Lynn; Marcelis, Leo F. M.; Steppe, Kathy

    2013-01-01

    Background Carbon assimilation and leaf-to-fruit sugar transport are, along with plant water status, the driving mechanisms for fruit growth. An integrated comprehension of the plant water and carbon relationships is therefore essential to better understand water and dry matter accumulation. Variations in stem diameter result from an integrated response to plant water and carbon status and are as such a valuable source of information. Methods A mechanistic water flow and storage model was used to relate variations in stem diameter to phloem sugar loading and sugar concentration dynamics in tomato. The simulation results were compared with an independent model, simulating phloem sucrose loading at the leaf level based on photosynthesis and sugar metabolism kinetics and enabled a mechanistic interpretation of the ‘one common assimilate pool’ concept for tomato. Key Results Combining stem diameter variation measurements and mechanistic modelling allowed us to distinguish instantaneous dynamics in the plant water relations and gradual variations in plant carbon status. Additionally, the model combined with stem diameter measurements enabled prediction of dynamic variables which are difficult to measure in a continuous and non-destructive way, such as xylem water potential and phloem hydrostatic potential. Finally, dynamics in phloem sugar loading and sugar concentration were distilled from stem diameter variations. Conclusions Stem diameter variations, when used in mechanistic models, have great potential to continuously monitor and interpret plant water and carbon relations under natural growing conditions. PMID:23186836

  16. Nanofiber diameter-dependent MAPK activity in osteoblasts.

    PubMed

    Jaiswal, Devina; Brown, Justin L

    2012-11-01

    The major challenge for bone tissue engineering lies in the fabrication of scaffolds that can mimic the extracellular matrix and promote osteogenesis. Electrospun fibers are being widely researched for this application due to high porosity, interconnectivity, and mechanical strength of the fibrous scaffolds. Electrospun poly methyl methacrylate (PMMA, 2.416 ± 0.100 μm) fibers were fabricated and etched using a 60% propylene glycol methyl ether acetate (PGMEA)/limonene (vol/vol) solution to obtain fiber diameters ranging from 2.5 to 0.5 μm in a time-dependent manner. The morphology of the fibrous scaffolds was evaluated using scanning electron microscopy and cellular compatibility with etchant-treated scaffold was assessed using immunoflurescence. Mitogen-activated protein kinases (MAPK) activation in response to different fiber diameter was evaluated with western blot as well as quantitative in-cell western. We report that electrospun micro-fibers can be etched to 0.552 ± 0.047 μm diameter without producing beads. Osteoblasts adhered to the fibers and a change in fiber diameter played a major role in modulating the activation of extracellular signal-regulated kinase (ERK) and p38 kinases with 0.882 ± 0.091 μm diameter fibers producing an inverse effect on ERK and p38 phosphorylation. These results indicate that nanofibers produced by wet etching can be effectively utilized to produce diameters that can differentially modulate MAPK activation patterns. PMID:22700490

  17. 10{times} reduction imaging at 13.4nm

    SciTech Connect

    Tichenor, D.A.; Kubiak, G.D.; Malinowski, M.E.

    1994-08-01

    A Schwarzschild imaging system has been designed to achieve 0.1 {mu}m resolution in a 0.4 mm diameter field of view when operated at a center wavelength of 13.4 nm. A decentered aperture is located on the convex primary resulting in an unobstructed numerical aperture of 0.08 and a corresponding depth of field of {plus_minus} 1 {mu}m. The Schwarzschild imaging objective is part of a five-reflection system containing the laser plasma source (LPS), condensing optics, turning mirror and reflection mask as shown in Figure 1. Extreme ultraviolet (EUV) radiation is generated by impinging a laser beam onto a copper target. The plasma source is driven by a Lambda Physik PLX 250 KrF excimer laser emitting 0.6 Joule, 20 ns pulses at a 200 Hz maximum repetition rate. Measurements of the source indicate that the full-width-half-maximum diameter is less than 100 {mu}m.

  18. Comparison of Epidermal/Dermal Damage Between the Long-Pulsed 1064 nm Nd:YAG and 755 nm Alexandrite Lasers Under Relatively High Fluence Conditions: Quantitative and Histological Assessments

    PubMed Central

    Lee, Ju Hwan; Park, So Ra; Jo, Jeong Ho; Park, Sung Yun; Seo, Young Kwon

    2014-01-01

    Abstract Objective: The purpose of this study was to compare degrees of epidermal/dermal tissue damage quantitatively and histologically after laser irradiation, to find ideal treatment conditions with relatively high fluence for skin rejuvenation. Background data: A number of recent studies have evaluated the clinical efficacy and safety of therapeutic lasers under relatively low fluence conditions. Methods: We transmitted the long-pulsed 1064 nm Nd:YAG and 755 nm Alexandrite lasers into pig skin according to different fluences and spot diameters, and estimated epidermal/dermal temperatures. Pig skin specimens were stained with hematoxylin and eosin for histological assessments. The fluence conditions comprised 26, 30, and 36 J/cm2, and the spot diameter conditions were 5, 8, and 10 mm. Pulse duration was 30 ms for all experiments. Results: Both lasers produced reliable thermal damage on the dermis without any serious epidermal injuries, under relatively high fluence conditions. The 1064 nm laser provided more active fibrous formations than the 755 nm laser, while higher risks for tissue damages simultaneously occurred. Conclusions: The ideal treatment conditions for skin rejuvenation were 8 mm diameter with 30 J/cm2 and 10 mm diameter with 26 J/cm2 for the 1064 nm laser, and 8 mm diameter with 36 J/cm2 and 10 mm diameter with 26 J/cm2 for the 755 nm laser. PMID:24992273

  19. High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias

    NASA Astrophysics Data System (ADS)

    Tan, B; Panchatsharam, S; Venkatakrishnan, K

    2009-03-01

    Laser ablative microvia formation has been widely accepted as an effective manufacturing method for interconnect via formation. Current conventional nanosecond laser microvia formation has reached its limit in terms of minimum via diameter and machining quality. Femtosecond laser has been investigated intensively for its superior machining quality and capability of producing much smaller features. However, the traditional femtosecond laser has very low power and is thus unable to meet the throughput requirement. In this paper we report ablative microvia formation using femtosecond lasers at megahertz repetition rates. Laser ablation was demonstrated for the first time for sub-10 µm interconnection via drilling at a throughput of 10 000 vias per second. A systematic study of the influence of a high repetition rate in femtosecond laser micromachining of silicon was carried out. The experiments were performed using an Yb-doped fibre amplified/oscillator laser with 1030 nm wavelength in an air environment. The effects of a high repetition rate on microvia formation were observed at ~300 fs for silicon substrates. Laser parameters along with threshold energy, via diameter, ablation depth, ablation rate and via quality were studied in detail to accentuate the need of femtosecond lasers for forming sub-10 µm diameter microvias. The experimental results show that femtosecond laser pulses with high repetition rates show unequivocally the advantages of short-pulse laser ablation for high-precision applications in micrometre-scale dimensions.

  20. Reduction of nanowire diameter beyond lithography limits by controlled catalyst dewetting

    NASA Astrophysics Data System (ADS)

    Calahorra, Yonatan; Kerlich, Alexander; Amram, Dor; Gavrilov, Arkady; Cohen, Shimon; Ritter, Dan

    2016-04-01

    Catalyst assisted vapour-liquid-solid is the most common method to realize bottom-up nanowire growth; establishing a parallel process for obtaining nanoscale catalysts at pre-defined locations is paramount for further advancement towards commercial nanowire applications. Herein, the effect of a selective area mask on the dewetting of metallic nanowire catalysts, deposited within lithography-defined mask pinholes, is reported. It was found that thin disc-like catalysts, with diameters of 120-450 nm, were transformed through dewetting into hemisphere-like catalysts, having diameters 2-3 fold smaller; the process was optimized to about 95% yield in preventing catalyst splitting, as would otherwise be expected due to their thickness-to-diameter ratio, which was as low as 1/60. The catalysts subsequently facilitated InP and InAs nanowire growth. We suggest that the mask edges prevent surface migration mediated spreading of the dewetted metal, and therefore induce its agglomeration into a single particle. This result presents a general strategy to diminish lithography-set dimensions for NW growth, and may answer a fundamental challenge faced by bottom-up nanowire technology.

  1. Construction and manufacturing of a microgearhead with 1.9-mm outer diameter for universal application

    NASA Astrophysics Data System (ADS)

    Thuerigen, Christian; Beckord, Ulrich; Bessey, Reiner

    1999-03-01

    Many new applications in medicine, telecommunication, automation systems etc. require powerful microdrives. Speeds up to 100.000 rpm and output torques in the (mu) Nm-range are typical characteristics of electromagnetic micromotors with diameters of a few millimeters. To accomplish a powerful microdrive, these micromotors have to be combined with micro gearheads of the same outer diameter. For such a micro gearhead with toothed wheels manufactured by use of the LIGA process a multi-stage planetary gear has many advantages. Many stages with different gear ratios can be combined to achieve a great number of different transmission, but manufacturing tolerances and a clearance for assembly must be respected. Therefore besides the selection of a reliable gearhead type and a suitable manufacturing process the optimization of the tooth profile is the key to the implementation of powerful micro gear systems with high output torques and efficiencies. The involute profile is the most suitable toothing, but many calculations and simulations are required to find the right modulus, total depth of teeth, profile offset etc. In a joint project Dr. Fritz Faulhaber GmbH and Co. KG and the Institut fuer Mikrotechnik Mainz GmbH developed a powerful microdevice with an outer diameter of only 1.9 mm.

  2. Carbon nanotubes with small and tunable diameters from poly(ferrocenylsilane)-block-polysiloxane diblock copolymers.

    PubMed

    Lu, Jennifer Q; Rider, David A; Onyegam, Emanuel; Wang, Hai; Winnik, Mitchell A; Manners, Ian; Cheng, Qian; Fu, Qiang; Liu, Jie

    2006-05-23

    Iron-containing nanostructures produced from various self-assembled poly(ferrocenylsilane)-block-polysiloxane thin films are catalytically active for the initiation and growth of high density, small diameter carbon nanotubes (CNTs). Moreover, the tube diameter and density can be tuned by adjusting the chain lengths of the block copolymer. Iron-containing nanostructures from poly(ferrocenylmethylethylsilane)-b-poly(methylvinylsiloxane) polymer with 25 repeat units of an iron-containing segment and 265 repeat units of a non-iron-containing segment are able to produce CNTs with diameters around or less than 1 nm. Lithographically selective growth of CNTs across a large surface area has been demonstrated using this polymer system. Under the same growth condition, it has been found that the yield of defect-free CNTs varies with the size of the catalytically active nanostructures, which are dictated by the chain lengths of the two blocks. This result indicates that, for a specific-sized catalyst nanocluster, a unique set of growth conditions is required for synthesizing high yield, defect-free CNTs. This finding further addresses the importance of using uniform-sized catalyst-containing nanostructures for consistently achieving high-yield and high-quality CNTs with a minimum number of defects and amount of amorphous carbon. PMID:16700610

  3. Ultra-Compact Multitip Scanning Probe Microscope with an Outer Diameter of 50 mm

    NASA Astrophysics Data System (ADS)

    Cherepanov, Vasily; Zubkov, Evgeny; Junker, Hubertus; Korte, Stefan; Blab, Marcus; Coenen, Peter; Voigtländer, Bert

    We present a multitip scanning tunneling microscope (STM) where four independent STM units are integrated on a diameter of 50 mm. The coarse positioning of the tips is done under the control of an optical microscope or an SEM in vacuum. The heart of this STM is a new type of piezoelectric coarse approach called Koala Drive which can have a diameter greater than 2.5 mm and a length smaller than 10 mm. Alternating movements of springs move a central tube which holds the STM tip or AFM sensor. This new operating principle provides a smooth travel sequence and avoids shaking which is intrinsically present for nanopositioners based on inertial motion with saw tooth driving signals. Inserting the Koala Drive in a piezo tube for xyz-scanning integrates a complete STM inside a 4 mm outer diameter piezo tube of <10 mm length. The use of the Koala Drive makes the scanning probe microscopy design ultra-compact and accordingly leads to a high mechanical stability. The drive is UHV, low temperature, and magnetic field compatible. The compactness of the Koala Drive allows building a four-tip STM as small as a single-tip STM with a drift of <0.2 nm/min and lowest resonance frequencies of 2.5 (xy) and 5.5 kHz (z). We present examples of the performance of the multitip STM designed using the Koala Drive.

  4. Diameter-dependent multiferroic functionality in hybrid core/shell NWs.

    PubMed

    Khan, U; Irfan, M; Li, W J; Adeela, N; Liu, P; Zhang, Q T; Han, X F

    2016-08-11

    A versatile approach towards nanofabrication of highly reproducible Co/BiCoO3 (Co/BCO) core/shell (CS) nanowires (NWs) with different diameters has been adopted by demonstrating easily available and low cost sol-gel and electrodeposition routes. X-ray diffraction (XRD) analysis confirmed the tetragonal system of the BCO nanoshells (NSs) with the space group P4mm. Scanning electron microscopy (SEM) clearly demonstrates the uniform morphology with well aligned CS NWs. The magnetization reversal processes (MRPs), experimentally and with analytical modelling, have been discussed for CS NWs with θ ranging from 0° (in-plane magnetic easy axis) to 90° (out-of-plane magnetic hard axis) with magnetic hysteresis loops and geometrical parameters. Crossover from the vortex to transverse reversal mode on increasing θ has been observed for all diameters. An exchange bias effect has been observed for smaller CS NWs diameters and it is attributed to the shell thickness of ∼25 nm. Furthermore, the magnetic anisotropy effect has been discussed in some detail. PMID:27465910

  5. 200-mm-diameter neutral beam source based on inductively coupled plasma etcher and silicon etching

    SciTech Connect

    Kubota, Tomohiro; Nukaga, Osamu; Ueki, Shinji; Sugiyama, Masakazu; Inamoto, Yoshimasa; Ohtake, Hiroto; Samukawa, Seiji

    2010-09-15

    The authors developed a neutral beam source consisting of a 200-mm-diameter inductively coupled plasma etcher and a graphite neutralization aperture plate based on the design of a neutral beam source that Samukawa et al. [Jpn. J. Appl. Phys., Part 2 40, L779 (2001)] developed. They measured flux and energy of neutral particles, ions, and photons using a silicon wafer with a thermocouple and a Faraday cup and calculated the neutralization efficiency. An Ar neutral beam flux of more than 1 mA/cm{sup 2} in equivalent current density and a neutralization efficiency of more than 99% were obtained. The spatial uniformity of the neutral beam flux was within {+-}6% within a 100 mm diameter. Silicon etching using a F{sub 2}-based neutral beam was done at an etch rate of about 47 nm/min, while Cl{sub 2}-based neutral beam realized completely no undercut. The uniformity of etch rate was less than {+-}5% within the area. The etch rate increased by applying bias power to the neutralization aperture plate, which shows that accelerated neutral beam was successfully obtained. These results indicate that the neutral beam source is scalable, making it possible to obtain a large-diameter and uniform neutral beam, which is inevitable for application to mass production.

  6. CoPt/CeO2 catalysts for the growth of narrow diameter semiconducting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tang, Lei; Li, Taotao; Li, Chaowei; Ling, Lin; Zhang, Kai; Yao, Yagang

    2015-11-01

    For the application of single-walled carbon nanotubes (SWNTs) in nanoelectronic devices, effective techniques for the growth of semiconducting SWNTs (s-SWNTs) with a specific diameter are still a great challenge. Herein, we report a facile strategy for the selective growth of narrow diameter distributed s-SWNTs using CoPt/CeO2 catalysts. The addition of Pt into a Co catalyst dramatically reduces the diameter distributions and even the chirality distributions of the as-grown SWNTs. Oxygen vacancies that are provided by mesoporous CeO2 are responsible for creating an oxidative environment to in situ etch metallic SWNTs (m-SWNTs). Atomic force microscope (AFM) and Raman spectroscopy characterizations indicate a narrow diameter distribution of 1.32 +/- 0.03 nm and the selective growth of s-SWNTs to 93%, respectively. In addition, electronic transport measurements also confirm that the Ion/Ioff ratio is mainly in the order of ~103. This work provides an effective strategy for the facile fabrication of narrow diameter distributed s-SWNTs, which will be beneficial to fundamental research and the broad application of SWNTs for future nanoelectronics.For the application of single-walled carbon nanotubes (SWNTs) in nanoelectronic devices, effective techniques for the growth of semiconducting SWNTs (s-SWNTs) with a specific diameter are still a great challenge. Herein, we report a facile strategy for the selective growth of narrow diameter distributed s-SWNTs using CoPt/CeO2 catalysts. The addition of Pt into a Co catalyst dramatically reduces the diameter distributions and even the chirality distributions of the as-grown SWNTs. Oxygen vacancies that are provided by mesoporous CeO2 are responsible for creating an oxidative environment to in situ etch metallic SWNTs (m-SWNTs). Atomic force microscope (AFM) and Raman spectroscopy characterizations indicate a narrow diameter distribution of 1.32 +/- 0.03 nm and the selective growth of s-SWNTs to 93%, respectively. In addition

  7. 308nm excimer laser in dermatology.

    PubMed

    Mehraban, Shadi; Feily, Amir

    2014-01-01

    308nm xenon-chloride excimer laser, a novel mode of phototherapy, is an ultraviolet B radiation system consisting of a noble gas and halide. The aim of this systematic review was to investigate the literature and summarize all the experiments, clinical trials and case reports on 308-nm excimer laser in dermatological disorders. 308-nm excimer laser has currently a verified efficacy in treating skin conditions such as vitiligo, psoriasis, atopic dermatitis, alopecia areata, allergic rhinitis, folliculitis, granuloma annulare, lichen planus, mycosis fungoides, palmoplantar pustulosis, pityriasis alba, CD30+ lympho proliferative disorder, leukoderma, prurigo nodularis, localized scleroderma and genital lichen sclerosus. Although the 308-nm excimer laser appears to act as a promising treatment modality in dermatology, further large-scale studies should be undertaken in order to fully affirm its safety profile considering the potential risk, however minimal, of malignancy, it may impose. PMID:25606333

  8. Effect of mesoporous TiO₂ bead diameter in working electrodes on the efficiency of dye-sensitized solar cells.

    PubMed

    Chen, Yang; Huang, Fuzhi; Chen, Dehong; Cao, Lu; Zhang, Xiao Li; Caruso, Rachel A; Cheng, Yi-Bing

    2011-10-17

    Mesoporous TiO₂ beads with diameters of 320±50, 550±50, and 830±40 nm, comprising interconnected and densely packed TiO₂ nanocrystals, were used as working electrodes for dye-sensitized solar cells (DSCs). These electrodes possess high surface areas and superior light-scattering properties, which are ideal for DSC applications. Although the electrode prepared by using 320±50 nm beads demonstrated the highest dye loading and the electrode prepared by using 550±50 nm beads showed the best light-scattering properties in the wavelength region λ=400-800 nm, DSC devices with working electrodes composed of 830±40 nm beads achieved the highest power conversion efficiencies of 9.0 % after treatment with TiCl₄. A higher electron diffusion rate (4.35×10⁻⁴ cm²  s⁻¹) and an extended electron lifetime (58 ms) were observed in DSCs composed of the largest beads, 830±40 nm, attributable to a reduced amount of inter-bead barriers and a relatively small percentage of TiO₂ nanocrystals on the surface of the beads, compared to cells containing 550±50 and 320±50 nm beads. PMID:21954197

  9. Predicting Hamstring Graft Diameter Using MRI and Anthropometry

    PubMed Central

    Fritsch, Brett A; Mhaskar, Vikram A; An, Vincent Vinh Gia; Scholes, Corey

    2016-01-01

    Objectives: Graft diameter is one variable that may affect outcome of ACL reconstruction. The ability to predict the size of a graft in a given patient pre-operatively may help guide graft selection and preparation technique. Various papers have correlated anthropometric data and MRI tendon measurements to intraoperative graft diameter, although no papers have investigated these together. The intra-operative diameter of a hamstring autograft will be influenced by graft preparation technique. Our study aimed to investigate the prediction of intraoperative graft diameter of 2 different graft construct techniques (4-strand semitendinosus versus quadrupled semitendinosus) using anthropometry and MRI measurements. Methods: Retrospective review of two groups of ACL reconstruction using different graft preparation techniques was performed. “Conventional” 4-strand gracilis + semitendinosus with fixed suspension at the femur and screw fixation at the tibia were compared with quadrupled semitendinosus grafts with adjustable suspensory fixation at each end (Graftlink). Cross-sectional areas (XSA) of the semitendinosus and gracilis tendons was measured in the axial slice of a T2 weighted MRI image using a region-of-interest tool. Stepwise linear regression using intraoperative graft diameter as the dependant variable was performed using MRI XSA of the semitendinosus and gracilis tendons, gender and height as predictors. Results: 129 ACL Reconstruction in 127 patients were done in the time period, 89 of which were done conventionally, and 40 which employed the Graftlink construct. The median graft diameter in the Graftlink group (8.5mm IQR8-9) was greater than that of the conventional group (8mm, IQR 7.5-8) (p < 0.001). MRI XSA of semitendinosus and height were statistically significant predictors of diameter in the Graftlink group (R2 = 51%), whilst MRI XSA of semitendinosus + gracilis and gender were predictors in the conventional group (R2 = 36%). Conclusion: Graftlink

  10. Synthesis of hematite (alpha-Fe2O3) nanorods: diameter-size and shape effects on their applications in magnetism, lithium ion battery, and gas sensors.

    PubMed

    Wu, Changzheng; Yin, Ping; Zhu, Xi; OuYang, Chuanzi; Xie, Yi

    2006-09-14

    We demonstrated in this paper the shape-controlled synthesis of hematite (alpha-Fe(2)O(3)) nanostructures with a gradient in the diameters (from less than 20 nm to larger than 300 nm) and surface areas (from 5.9 to 52.3 m(2)/g) through an improved synthetic strategy by adopting a high concentration of inorganic salts and high temperature in the synthesis systems to influence the final products of hematite nanostructures. The benefits of the present work also stem from the first report on the <20-nm-diameter and porous hematite nanorods, as well as a new facile strategy to the less-than-20-nm nanorods, because the less-than-20-nm diameter size meets the vital size domain for magnetization properties in hematite. Note that the porous and nonporous hematite one-dimensional nanostructures with diameter gradients give us the first opportunity to investigate the Morin temperature evolution of nanorod diameter and porosity. Evidently, the magnetic properties for nanorods exhibit differences compared with those for the spherical particle counterparts. Hematite nanorods are strongly dependent on their diameter size and porosity, where the magnetization is not sensitive to the size evolution from submicron particles to the 60-90 nm nanorods, while the magnetic properties change significantly in the case of <20 nm. In other words, for the magnetic properties of nanorods, in a comparable size range, the porous existence could also influence the magnetic behavior. Moreover, applications in formaldehyde (HCHO) gas sensors and lithium batteries for the hematite nanostructures with the diameter/surface area gradient reveal that the performance of electrochemical and gas-sensor properties strongly depends on the diameter size and Brunauer-Emmett-Teller (BET) surface areas, which is consistent with the crystalline point of view. Thus, this work not only provides the first example of the fabrication of hematite nanostructure sensors for detecting HCHO gas, but also reveals that the

  11. Optical extension at the 193-nm wavelength

    NASA Astrophysics Data System (ADS)

    Zandbergen, Peter; McCallum, Martin; Amblard, Gilles R.; Domke, Wolf-Dieter; Smith, Bruce W.; Zavyalova, Lena; Petersen, John S.

    1999-07-01

    Lithography at 193nm is the first optical lithography technique that will be introduced for manufacturing of technology levels. where the required dimensions are smaller than the actual wavelength. This paper explores several techniques to extend 193nm to low k1 lithography. Most attention is given to binary mask solution in at 130nm dimensions, where k1 is 0.4. Various strong and Gaussian quadrupole illuminators were designed, manufactured and tested for this application. Strong quadrupoles show that largest DOF improvements. The drawback however, is that these strong quadrupoles are very duty cycle and dimensions specific, resulting in large proximity biases between different duty cycles. Due to their design, Gaussian quadrupoles sample much wider frequency ranges, resulting in less duty cycles specific DOF improvements and less proximity basis. At sub-130nm dimensions, strong phase shift masks provide significant latitude improvements, when compared to binary masks with quadrupole illumination. However, differences in dose to size for different duty cycles were up to 25 percent. For definition of contact holes, linewidth biasing through silylation, a key feature of the CARL bi-layer resist approach, demonstrated significant DOF latitude improvements compared to SLR at 140nm and 160nm contact holes.

  12. Thermal lensing in Nd:YVO4 laser with in-band pumping at 914 nm

    NASA Astrophysics Data System (ADS)

    Waritanant, Tanant; Major, Arkady

    2016-05-01

    Thermal lensing in an Nd:YVO4 laser system operating at 1064 nm with in-band pumping at 914 nm was characterized. The focal length of the thermal lens in the crystal was calculated using ABCD matrix formalism from the experimental data of the output beam diameter measurements made at different output power levels. The determined focal lengths of thermal lens were as strong as 4.4 diopters at 3.5 W of output power. The experimental results agree well with the finite element analysis of the developed laser system. A numerical comparison of the thermal lensing effect with 914-, 888-, 880-nm pumping, and with a standard 808-nm pumping was also made, demonstrating effective reduction of thermal lensing up to 2.1 times.

  13. The experimental study of a CW 1080 nm multi-point pump fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Xuexia; Ge, Tingwu; Ding, Xing; Tan, Qirui; Wang, Zhiyong

    2016-07-01

    In this paper, we report on a CW 1080 nm fiber laser cascaded-pumped by a CW 975 nm diode laser. The fiber used in the experiment has a core diameter of 20 μm (NA  =  0.06), inner clad of 400 μm (NA  =  0.46), and an absorption coefficient of about 1.26 dB m‑1 at 975 nm. An output power of 780 W with an optical conversion efficiency of 71% has been achieved at a pump light of 1.1 kW. To the best of our knowledge, this is the first time that a 1080 nm CW fiber laser has used a cascaded-pump coupler.

  14. Fabrication of 250-nm-hole arrays in glass and fused silica by UV laser ablation

    NASA Astrophysics Data System (ADS)

    Karstens, R.; Gödecke, A.; Prießner, A.; Ihlemann, J.

    2016-09-01

    Parallel nanohole drilling in glass using an ArF excimer laser (193 nm) is demonstrated. For the first time, hole arrays with 500 nm pitch and individual holes with 250 nm diameter and more than 100 nm depth are fabricated by phase mask imaging using a Schwarzschild objective. Holes in soda lime glass are drilled by direct ablation; fused silica is processed by depositing a SiOx-film on SiO2, patterning the SiOx by ablation, and finally oxidizing the remaining SiOx to SiO2. Thermally induced ordered dewetting of noble metal films deposited on such templates may be used for the fabrication of plasmonic devices.

  15. Low-noise low-jitter 32-pixels CMOS single-photon avalanche diodes array for single-photon counting from 300 nm to 900 nm.

    PubMed

    Scarcella, Carmelo; Tosi, Alberto; Villa, Federica; Tisa, Simone; Zappa, Franco

    2013-12-01

    We developed a single-photon counting multichannel detection system, based on a monolithic linear array of 32 CMOS SPADs (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diodes). All channels achieve a timing resolution of 100 ps (full-width at half maximum) and a photon detection efficiency of 50% at 400 nm. Dark count rate is very low even at room temperature, being about 125 counts/s for 50 μm active area diameter SPADs. Detection performance and microelectronic compactness of this CMOS SPAD array make it the best candidate for ultra-compact time-resolved spectrometers with single-photon sensitivity from 300 nm to 900 nm. PMID:24387425

  16. Low-noise low-jitter 32-pixels CMOS single-photon avalanche diodes array for single-photon counting from 300 nm to 900 nm

    SciTech Connect

    Scarcella, Carmelo; Tosi, Alberto Villa, Federica; Tisa, Simone; Zappa, Franco

    2013-12-15

    We developed a single-photon counting multichannel detection system, based on a monolithic linear array of 32 CMOS SPADs (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diodes). All channels achieve a timing resolution of 100 ps (full-width at half maximum) and a photon detection efficiency of 50% at 400 nm. Dark count rate is very low even at room temperature, being about 125 counts/s for 50 μm active area diameter SPADs. Detection performance and microelectronic compactness of this CMOS SPAD array make it the best candidate for ultra-compact time-resolved spectrometers with single-photon sensitivity from 300 nm to 900 nm.

  17. 946 nm Diode Pumped Laser Produces 100mJ

    NASA Technical Reports Server (NTRS)

    Axenson, Theresa J.; Barnes, Norman P.; Reichle, Donald J., Jr.

    2000-01-01

    An innovative approach to obtaining high energy at 946 nm has yielded 101 mJ of laser energy with an optical-to-optical slope efficiency of 24.5%. A single gain module resonator was evaluated, yielding a maximum output energy of 50 mJ. In order to obtain higher energy a second gain module was incorporated into the resonator. This innovative approach produced un-surprised output energy of 101 mJ. This is of utmost importance since it demonstrates that the laser output energy scales directly with the number of gain modules. Therefore, higher energies can be realized by simply increasing the number of gain modules within the laser oscillator. The laser resonator incorporates two gain modules into a folded "M-shaped" resonator, allowing a quadruple pass gain within each rod. Each of these modules consists of a diode (stack of 30 microlensed 100 Watt diode array bars, each with its own fiber lens) end-pumping a Nd:YAG laser rod. The diode output is collected by a lens duct, which focuses the energy into a 2 mm diameter flat to flat octagonal pump area of the laser crystal. Special coatings have been developed to mitigate energy storage problems, including parasitic lasing and amplified spontaneous emission (ASE), and encourage the resonator to operate at the lower gain transition at 946 nm.

  18. Large Diameter, Radiative Extinction Experiments with Decane Droplets in Microgravity

    NASA Technical Reports Server (NTRS)

    Easton, John; Tien, James; Dietrich, Daniel

    1999-01-01

    The extinction of a diffusion flame is of fundamental interest in combustion science. Linan, Law, and Chung and Law analytically and experimentally determined an extinction boundary in terms of droplet diameter and pressure for a single droplet due to Damkohler, or blowoff, extinction. More recently, other researchers demonstrated extinction due to finite rate kinetics in reduced gravity for free droplets of heptane. Chao modeled the effect of radiative heat loss on a quasi-steady spherically symmetric single droplet burning in the absence of buoyancy. They determined that for increasing droplet diameter, a second limit can be reached such that combustion is no longer possible. This second, larger droplet diameter limit arises due to radiative heat loss, which increases with increasing droplet and flame diameter. This increase in radiative heat loss arises due to an increase in the surface area of the flame. Recently, Marchese modeled fuel droplets with detailed chemistry and radiative effects, and compared the results to other work. The modeling also showed the importance of radiative loss and radiative extinction Experiments examined the behavior of a large droplet of decane burning in reduced gravity onboard the NASA Lewis DC-9 aircraft, but did not show a radiative extinction boundary due to g-jitter (Variations in gravitational level and direction) effects. Dietrich conducted experiments in the reduced gravity environment of the Space Shuttle. This work showed that the extinction diameter of methanol droplets increased when the initial diameter of the droplets was large (in this case, approximately 5 mm). Theoretical results agreed with these experimental results only when the theory included radiative effects . Radiative extinction was experimentally verified by Nayagam in a later Shuttle mission. The following work focuses on the combustion and extinction of a single fuel droplet. The goal is to experimentally determine a large droplet diameter limit that

  19. Facile method to control the diameter and density of carbon nanotubes by using a catalyst-embedded supporting layer

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Woong; Han, Jaeseok; Im, Hyunsik; Choi, WonChel; Park, Young S.; Yoon, Seok-Beom

    2015-06-01

    We have investigated an effective method to control the diameter and the density of carbon nanotubes (CNTs) by introducing a catalyst-embedded supporting layer (CSL) prepared by using rf-magnetron sputtering with a mixed target consisting of Fe and Al2O3. The type of CNTs was changed from single-walled CNTs with a diameter of 0.85 ~ 1.55 nm to multi-walled CNTs with increasing rf-magnetron sputtering power. The controllability of the diameter and the density of the CNTs was confirmed to have been improved by using the rf power during the sputtering of the CSL and the concentration of Fe in the mixed target, respectively.

  20. Silver nanoparticles of 70 nm and 20 nm affect differently the biology of human neutrophils.

    PubMed

    Poirier, Michelle; Simard, Jean-Christophe; Girard, Denis

    2016-05-01

    The influence of size of nanoparticles (NP), especially in regard to pulmonary toxicity, has been widely investigated. In general, NP with smaller diameters are more pro-inflammatory in vivo, at least in terms of neutrophil influx. Nevertheless, the influence of size of NP on polymorphonuclear neutrophil (PMN) cell biology is poorly documented. In the study here, it was decided to determine if AgNP with a diameter of 70 nm (AgNP70) will alter the biology of human PMN similarly to AgNP20 previously reported to induce apoptosis and inhibit de novo protein synthesis. The results here indicated that, in contrast to AgNP20, AgNP70 delayed PMN apoptosis. However, both AgNP20 and AgNP70 inhibited de novo protein synthesis. Both forms of AgNP did not significantly increase reactive oxygen species (ROS) production, but AgNP20 significantly increased the cell production of the CXCL8 chemokine (IL-8). In addition, AgNP20, but not AgNP70, induced the release of albumin and matrix metalloproteinase-9 (MMP-9/gelatinase B) into culture supernatants. Consistent with this latter observation, gelatinase activity was increased by AgNP20, as assessed by zymography. From these outcomes, it is concluded that two NP with different initial diameters can possess similar - as well as distinct - biological properties in modulating human PMN functions. These outcomes are testimony to the complexity of the modes of action of NP at the cellular level. PMID:26619040

  1. Control of the Diameter and Chiral Angle Distributions during Production of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pavel

    2009-01-01

    Many applications of single wall carbon nanotubes (SWCNT), especially in microelectronics, will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.) Especially fascinating is the possibility of quantum conductors that require metallic armchair nanotubes. However, as produced SWCNT samples are polydisperse, with many (n,m) types present and typical approx.1:2 metal/semiconductor ratio. Nanotube nucleation models predict that armchair nuclei are energetically preferential due to formation of partial triple bonds along the armchair edge. However, nuclei can not reach any meaningful thermal equilibrium in a rapidly expanding and cooling plume of carbon clusters, leading to polydispersity. In the present work, SWCNTs were produced by a pulsed laser vaporization (PLV) technique. The carbon vapor plume cooling rate was either increased by change in the oven temperature (expansion into colder gas), or decreased via "warm-up" with a laser pulse at the moment of nucleation. The effect of oven temperature and "warm-up" on nanotube type population was studied via photoluminescence, UV-Vis-NIR absorption and Raman spectroscopy. It was found that reduced temperatures leads to smaller average diameters, progressively narrower diameter distributions, and some preference toward armchair structures. "Warm-up" shifts nanotube population towards arm-chair structures as well, but the effect is small. Possible improvement of the "warm-up" approach to produce armchair SWCNTs will be discussed. These results demonstrate that PLV production technique can provide at least partial control over the nanotube (n,m) population. In addition, these results have implications for the understanding the nanotube nucleation mechanism in the laser oven.

  2. The Double-ended 750 nm and 532 nm Laser Output from PPLN-FWM

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Li, Yu-Xiang; Yao, Jian-Quan; Guo, Ling; Wang, Zhuo; Han, Sha-Sha; Zhang, Cui-Ying; Zhong, Kai

    2013-06-01

    We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things. A kind of optical maser is developed, in which the semiconductor module outputs the 808 nm pump light and then it goes into a double-clad Nd3+ :YAG monocrystal optical fiber through the intermediate coupler and forms a 1064 nm laser. The laser outputs come from both left and right terminals. In the right branch, the laser goes into the right cycle polarization LinNbO3 (PPLN) crystal through the right coupler, produces the optical parametric oscillation and forms the signal light λ1 (1500 nm), the idle frequency light λ2 (3660.55 nm), and the second-harmonic of the signal light λ3 (750 nm). These three kinds of light and the pump light λ4 together form the frequency matching and the quasi-phase matching, then the four-wave mixing occurs to create the high-gain light at wavelength 750 nm. Meanwhile, in the left branch, the laser goes into the left PPLN crystal through the left coupler, engenders frequency doubling and forms the light at wavelength 532 nm. That is to say, the optical maser provides 750 nm and 532 nm dual-wavelength laser outputting from two terminals, which is workable.

  3. Angular diameters of the carbon stars UU Aurigae, Y Canum Venaticorum, and TX PISCIUM from optical long-baseline interferometry

    NASA Astrophysics Data System (ADS)

    Quirrenbach, A.; Mozurkewich, D.; Hummel, C. A.; Buscher, D. F.; Armstrong, J. T.

    1994-05-01

    The angular diameters of the three carbon stars UU Aur, Y CVn, and TX Psc have been determined with the MkIII Optical Interferometer. Measurements of UU Aur at λλ= 712, 754, and 800nm agree well with each other; the weighted mean for the uniform disk diameter is θ_UD_ = 11.28 +/-0.21mas. For Y CVn, θ_UD_ = 13.81 +/-0.43mas is obtained at 800nm. There are indications of temporal variations of the diameter of TX Psc; values between 9.4 and 11.1mas were measured for this star. Effective temperatures are calculated for these three stars and for six other carbon stars for which diameters measured with the lunar occultation technique have been published. These fundamentally determined effective temperatures correlate well with, but are on average about 100K cooler than, effective temperatures for the same stars obtained with the infrared flux method by Tsuji (1981). Color temperatures determined by Baumert (1972) and by Gow (1977) correlate poorly with effective temperatures.

  4. 635nm diode laser biostimulation on cutaneous wounds

    NASA Astrophysics Data System (ADS)

    Solmaz, Hakan; Gülsoy, Murat; Ülgen, Yekta

    2014-05-01

    Biostimulation is still a controversial subject in wound healing studies. The effect of laser depends of not only laser parameters applied but also the physiological state of the target tissue. The aim of this project is to investigate the biostimulation effects of 635nm laser irradiation on the healing processes of cutaneous wounds by means of morphological and histological examinations. 3-4 months old male Wistar Albino rats weighing 330 to 350 gr were used throughout this study. Low-level laser therapy was applied through local irradiation of red light on open skin excision wounds of 5mm in diameter prepared via punch biopsy. Each animal had three identical wounds on their right dorsal part, at which two of them were irradiated with continuous diode laser of 635nm in wavelength, 30mW of power output and two different energy densities of 1 J/cm2 and 3 J/cm2. The third wound was kept as control group and had no irradiation. In order to find out the biostimulation consequences during each step of wound healing, which are inflammation, proliferation and remodeling, wound tissues removed at days 3, 7, 10 and 14 following the laser irradiation are morphologically examined and than prepared for histological examination. Fragments of skin including the margin and neighboring healthy tissue were embedded in paraffin and 6 to 9 um thick sections cut are stained with hematoxylin and eosin. Histological examinations show that 635nm laser irradiation accelerated the healing process of cutaneous wounds while considering the changes of tissue morphology, inflammatory reaction, proliferation of newly formed fibroblasts and formation and deposition of collagen fibers. The data obtained gives rise to examine the effects of two distinct power densities of low-level laser irradiation and compare both with the non-treatment groups at different stages of healing process.

  5. Memory, emotion, and pupil diameter: Repetition of natural scenes.

    PubMed

    Bradley, Margaret M; Lang, Peter J

    2015-09-01

    Recent studies have suggested that pupil diameter, like the "old-new" ERP, may be a measure of memory. Because the amplitude of the old-new ERP is enhanced for items encoded in the context of repetitions that are distributed (spaced), compared to massed (contiguous), we investigated whether pupil diameter is similarly sensitive to repetition. Emotional and neutral pictures of natural scenes were viewed once or repeated with massed (contiguous) or distributed (spaced) repetition during incidental free viewing and then tested on an explicit recognition test. Although an old-new difference in pupil diameter was found during successful recognition, pupil diameter was not enhanced for distributed, compared to massed, repetitions during either recognition or initial free viewing. Moreover, whereas a significant old-new difference was found for erotic scenes that had been seen only once during encoding, this difference was absent when erotic scenes were repeated. Taken together, the data suggest that pupil diameter is not a straightforward index of prior occurrence for natural scenes. PMID:25943211

  6. Parametric Probability Distribution Functions for Axon Diameters of Corpus Callosum

    PubMed Central

    Sepehrband, Farshid; Alexander, Daniel C.; Clark, Kristi A.; Kurniawan, Nyoman D.; Yang, Zhengyi; Reutens, David C.

    2016-01-01

    Axon diameter is an important neuroanatomical characteristic of the nervous system that alters in the course of neurological disorders such as multiple sclerosis. Axon diameters vary, even within a fiber bundle, and are not normally distributed. An accurate distribution function is therefore beneficial, either to describe axon diameters that are obtained from a direct measurement technique (e.g., microscopy), or to infer them indirectly (e.g., using diffusion-weighted MRI). The gamma distribution is a common choice for this purpose (particularly for the inferential approach) because it resembles the distribution profile of measured axon diameters which has been consistently shown to be non-negative and right-skewed. In this study we compared a wide range of parametric probability distribution functions against empirical data obtained from electron microscopy images. We observed that the gamma distribution fails to accurately describe the main characteristics of the axon diameter distribution, such as location and scale of the mode and the profile of distribution tails. We also found that the generalized extreme value distribution consistently fitted the measured distribution better than other distribution functions. This suggests that there may be distinct subpopulations of axons in the corpus callosum, each with their own distribution profiles. In addition, we observed that several other distributions outperformed the gamma distribution, yet had the same number of unknown parameters; these were the inverse Gaussian, log normal, log logistic and Birnbaum-Saunders distributions. PMID:27303273

  7. Soot properties and species measurements in a two-meter diameter JP-8 pool fire.

    SciTech Connect

    Shaddix, Christopher R.; Murphy, Jeffrey J.

    2003-06-01

    A tunable diode laser absorption spectroscopy probe was used to measure in situ soot properties and species concentrations in two-meter diameter JP-8 pool fires. Twelve tests were performed at the Lurance Canyon Bum Site operated by Sandia in Albuquerque, New Mexico. Seven of the tests were conducted with the probe positioned close to the centerline at heights above the pool surface ranging from 0.5 m to 2.0 mm in 0.25 m increments. For the remaining five tests, the probe was positioned at two heights 0.3 m from the centerline and at three heights 0.5 m from the centerline. Soot concentration was determined using a soot absorption measurement based on the transmission of a solid-state red laser (635 nm) through the 3.7 cm long probe volume. Soot temperature and a second estimate of soot concentration were measured using two-color optical pyrometry at 850 nm and la00 nm. The effective data rate for these measurements was 10 Mz. Finally, tunable diode laser absorption spectroscopy was used to qualitatively estimate water concentration at a rate of 1 kHz. To improve signal-to-noise, these data were averaged to an effective rate of 2 Hz. The results presented include the statistics, probability density functions, and spectral density functions of soot concentration, soot temperature, and approximate water concentrations at the different measurement locations throughout the fire.

  8. Gold Nanohole Array with Sub-1 nm Roughness by Annealing for Sensitivity Enhancement of Extraordinary Optical Transmission Biosensor

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Irannejad, Mehrdad; Yavuz, Mustafa; Cui, Bo

    2015-05-01

    Nanofabrication technology plays an important role in the performance of surface plasmonic devices such as extraordinary optical transmission (EOT) sensor. In this work, a double liftoff process was developed to fabricate a series of nanohole arrays of a hole diameter between 150 and 235 nm and a period of 500 nm in a 100-nm-thick gold film on a silica substrate. To improve the surface quality of the gold film, thermal annealing was conducted, by which an ultra-smooth gold film with root-mean-square (RMS) roughness of sub-1 nm was achieved, accompanied with a hole diameter shrinkage. The surface sensitivity of the nanohole arrays was measured using a monolayer of 16-mercaptohexadecanoic acid (16-MHA) molecule, and the surface sensitivity was increased by 2.5 to 3 times upon annealing the extraordinary optical transmission (EOT) sensor.

  9. Object localization with 10 nm accuracy by x-ray phase contrast projection imaging

    SciTech Connect

    Ollinger, C.; Fuhse, C.; Kalbfleisch, S.; Tucoulou, R.; Salditt, T.

    2007-07-30

    The present work focuses on the question of localizing single object by hard x-ray phase contrast projection imaging. The authors present a setup where an x-ray channel waveguide defines a 'quasi-point source' used to illuminate and image an object in a highly coherent cone beam. Knife edge fluorescence scans revealed a beam diameter of 75 nm at a distance of 30 {mu}m behind the guide. The recorded image corresponds to an in-line hologram of the object which can be reconstructed numerically. Object translations and associated shifts in the hologram allow for the 10 nm localization accuracy.

  10. 810nm, 980nm, 1470nm and 1950nm diode laser comparison: a preliminary "ex vivo" study on oral soft tissues

    NASA Astrophysics Data System (ADS)

    Fornaini, Carlo; Merigo, Elisabetta; Sozzi, Michele; Selleri, Stefano; Vescovi, Paolo; Cucinotta, Annamaria

    2015-02-01

    The introduction of diode lasers in dentistry has several advantages, mainly consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibers. At the moment the two diode wavelengths normally utilized in the dental field are 810 and 980 nm for soft tissues treatments. The aim of this study was to compare the efficacy of four different diode wavelengths: 810, 980, 1470 and 1950 nm diode laser for the ablation of soft tissues. Several samples of veal tongue were exposed to the four different wavelengths, at different fluences. The internal temperature of the soft tissues, in the area close to the beam, was monitored with thermocouple during the experiment. The excision quality of the exposed samples have been characterized by means of an optical microscope. Tissue damages and the cut regularity have been evaluated on the base of established criteria. The lowest thermal increase was recorded for 1950 nm laser. Best quality and speed of incision were obtained by the same wavelength. By evaluating epithelial, stromal and vascular damages for all the used wavelengths, the best result, in terms of "tissue respect", have been obtained for 1470 and 1950 nm exposures. From the obtained results 1470 and 1950 nm diode laser showed to be the best performer wavelengths among these used in this "ex vivo" study, probably due to their greatest affinity to water.

  11. Radiation Failures in Intel 14nm Microprocessors

    NASA Technical Reports Server (NTRS)

    Bossev, Dobrin P.; Duncan, Adam R.; Gadlage, Matthew J.; Roach, Austin H.; Kay, Matthew J.; Szabo, Carl; Berger, Tammy J.; York, Darin A.; Williams, Aaron; LaBel, K.; Ingalls, James D.

    2016-01-01

    In this study the 14 nm Intel Broadwell 5th generation core series 5005U-i3 and 5200U-i5 was mounted on Dell Inspiron laptops, MSI Cubi and Gigabyte Brix barebones and tested with Windows 8 and CentOS7 at idle. Heavy-ion-induced hard- and catastrophic failures do not appear to be related to the Intel 14nm Tri-Gate FinFET process. They originate from a small (9 m 140 m) area on the 32nm planar PCH die (not the CPU) as initially speculated. The hard failures seem to be due to a SEE but the exact physical mechanism has yet to be identified. Some possibilities include latch-ups, charge ion trapping or implantation, ion channels, or a combination of those (in biased conditions). The mechanism of the catastrophic failures seems related to the presence of electric power (1.05V core voltage). The 1064 nm laser mimics ionization radiation and induces soft- and hard failures as a direct result of electron-hole pair production, not heat. The 14nm FinFET processes continue to look promising for space radiation environments.

  12. Diameter-dependent solubility of single-walled carbon nanotubes.

    PubMed

    Duque, Juan G; Parra-Vasquez, A Nicholas G; Behabtu, Natnael; Green, Micah J; Higginbotham, Amanda L; Price, B Katherine; Leonard, Ashley D; Schmidt, Howard K; Lounis, Brahim; Tour, James M; Doorn, Stephen K; Cognet, Laurent; Pasquali, Matteo

    2010-06-22

    We study the solubility and dispersibility of as-produced and purified HiPco single-walled carbon nanotubes (SWNTs). Variation in specific operating conditions of the HiPco process are found to lead to significant differences in the respective SWNT solubilities in oleum and surfactant suspensions. The diameter distributions of SWNTs dispersed in surfactant solutions are batch-dependent, as evidenced by luminescence and Raman spectroscopies, but are identical for metallic and semiconducting SWNTs within a batch. We thus find that small diameter SWNTs disperse at higher concentration in aqueous surfactants and dissolve at higher concentration in oleum than do large-diameter SWNTs. These results highlight the importance of controlling SWNT synthesis methods in order to optimize processes dependent on solubility, including macroscopic processing such as fiber spinning, material reinforcement, and films production, as well as for fundamental research in type selective chemistry, optoelectronics, and nanophotonics. PMID:20521799

  13. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±∼20% and ±∼40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  14. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±˜20% and ±˜40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  15. Blood viscosity in tube flow: dependence on diameter and hematocrit.

    PubMed

    Pries, A R; Neuhaus, D; Gaehtgens, P

    1992-12-01

    Since the original publications by Martini et al. (Dtsch. Arch. Klin. Med. 169: 212-222, 1930) and Fahraeus and Lindqvist (Am. J. Physiol. 96: 562-568, 1931), it has been known that the relative apparent viscosity of blood in tube flow depends on tube diameter. Quantitative descriptions of this effect and of the dependence of blood viscosity on hematocrit in the different diameter tubes are required for the development of hydrodynamic models of blood flow through the microcirculation. The present study provides a comprehensive data base for the description of relative apparent blood viscosity as a function of tube diameter and hematocrit. Data available from the literature are compiled, and new experimental data obtained in a capillary viscometer are presented. The combined data base comprises measurements at high shear rates (u > or = 50 s-1) in tubes with diameters ranging from 3.3 to 1,978 microns at hematocrits of up to 0.9. If corrected for differences in suspending medium viscosity and temperature, the data show remarkable agreement. Empirical fitting equations predicting relative apparent blood viscosity from tube diameter and hematocrit are presented. A pronounced change in the hematocrit dependence of relative viscosity is observed in a range of tube diameters in which viscosity is minimal. While a linear hematocrit-viscosity relationship is found in tubes of < or = 6 microns, an overproportional increase of viscosity with hematocrit prevails in tubes of > or = 9 microns. This is interpreted to reflect the hematocrit-dependent transition from single- to multifile arrangement of cells in flow. PMID:1481902

  16. The heliometric Astrolabe, a new instrument for solar diameter observations

    NASA Astrophysics Data System (ADS)

    Andrei, A. H.; Reis Neto, E.; D'Ávila, V. A.; Penna, J. L.; Assafin, M.; Boscardin, S. C.; De Avila, K. N.

    2006-10-01

    The Observatorio Nacional takes part in the Reseau de Suivi au Sol du Rayon Solaire (the international solar diameter monitoring network) which co-participates in the PICARD micro satellite, to be launched in 2008 to study the Earth climate and Sun variability relationship. A new instrument, a heliometer, was devised in order to minimize the atmospheric turbulence and reach data accuracy compatible with PICARD's. The heliometer principle of double images will be added to the astrolabe metrological quality, and fully digitized acquisition. The objective is to obtain two simultaneous images from the Sun, with fixed angular separation of about 30', which variation will contain the signature of the diameter variation.

  17. Diode laser (980nm) cartilage reshaping

    NASA Astrophysics Data System (ADS)

    El Kharbotly, A.; El Tayeb, T.; Mostafa, Y.; Hesham, I.

    2011-03-01

    Loss of facial or ear cartilage due to trauma or surgery is a major challenge to the otolaryngologists and plastic surgeons as the complicated geometric contours are difficult to be animated. Diode laser (980 nm) has been proven effective in reshaping and maintaining the new geometric shape achieved by laser. This study focused on determining the optimum laser parameters needed for cartilage reshaping with a controlled water cooling system. Harvested animal cartilages were angulated with different degrees and irradiated with different diode laser powers (980nm, 4x8mm spot size). The cartilage specimens were maintained in a deformation angle for two hours after irradiation then released for another two hours. They were serially measured and photographed. High-power Diode laser irradiation with water cooling is a cheep and effective method for reshaping the cartilage needed for reconstruction of difficult situations in otorhinolaryngologic surgery. Key words: cartilage,diode laser (980nm), reshaping.

  18. 193 nm Excimer laser processing of Si/Ge/Si(100) micropatterns

    NASA Astrophysics Data System (ADS)

    Gontad, F.; Conde, J. C.; Chiussi, S.; Serra, C.; González, P.

    2016-01-01

    193 nm Excimer laser assisted growth and crystallization of amorphous Si/Ge bilayer patterns with circular structures of 3 μm diameter and around 25 nm total thickness, is presented. Amorphous patterns were grown by Laser induced Chemical Vapor Deposition, using nanostencils as shadow masks and then irradiated with the same laser to induce structural and compositional modifications for producing crystalline SiGe alloys through fast melting/solidification cycles. Compositional and structural analyses demonstrated that pulses of 240 mJ/cm2 lead to graded SiGe alloys with Si rich discs of 2 μm diameter on top, a buried Ge layer, and Ge rich SiGe rings surrounding each feature, as predicted by previous numerical simulation.

  19. Super ACO FEL oscillation at 300 nm

    NASA Astrophysics Data System (ADS)

    Nutarelli, D.; Garzella, D.; Renault, E.; Nahon, L.; Couprie, M. E.

    2000-05-01

    Some recent improvements, involving both the optical cavity mirrors and the positron beam dynamics in the storage ring, have allowed us to achieve a laser oscillation at 300 nm on the Super ACO Storage Ring FEL. The Super ACO storage ring is operated at 800 MeV which is the nominal energy for the usual synchrotron radiation users, and the highest energy for a storage ring FEL. The lasing at 300 nm could be kept during 2 h per injection, with a stored current ranging between 30 and 60 mA. The FEL characteristics are presented here. The longitudinal stability and the FEL optics behaviour are also discussed.

  20. 1550-nm wavelength-tunable HCG VCSELs

    NASA Astrophysics Data System (ADS)

    Chase, Christopher; Rao, Yi; Huang, Michael; Chang-Hasnain, Connie

    2014-02-01

    We demonstrate wavelength-tunable VCSELs using high contrast gratings (HCGs) as the top output mirror on VCSELs, operating at 1550 nm. Tunable HCG VCSELs with a ~25 nm mechanical tuning range as well as VCSELs with 2 mW output power were realized. Error-free operation of an optical link using directly-modulated tunable HCG VCSELs transmitting at 1.25 Gbps over 18 channels spaced by 100 GHz and transmitted over 20 km of single mode fiber is demonstrated, showing the suitability of the HCG tunable VCSEL as a low cost source for WDM communications systems.

  1. Comparative study of Nd:KGW lasers pumped at 808 nm and 877 nm

    NASA Astrophysics Data System (ADS)

    Huang, Ke; Ge, Wen-Qi; Zhao, Tian-Zhuo; He, Jian-Guo; Feng, Chen-Yong; Fan, Zhong-Wei

    2015-10-01

    The laser performance and thermal analysis of Nd:KGW laser continuously pumped by 808 nm and 877 nm are comparatively investigated. Output power of 670 mW and 1587 mW, with nearly TEM00 mode, are achieved respectively at 808 nm pump and 877 nm pump. Meanwhile, a high-power passively Q-switched Nd:KGW/Cr4+:YAG laser pumped at 877 nm is demonstrated. An average output power of 1495 mW is obtained at pump power of 5.22 W while the laser is operating at repetition of 53.17 kHz. We demonstrate that 877 nm diode laser is a more potential pump source for Nd:KGW lasers.

  2. 188 W nanosecond pulsed fiber amplifier at 1064 nm

    NASA Astrophysics Data System (ADS)

    Li, Zebiao; Guo, Chao; Li, Qi; Zhao, Pengfei; Li, Chengyu; Huang, Zhihua; Tang, Xuan; Lin, Honghuan; Xu, Shanhui; Yang, Zhongmin; Wang, Jianjun; Jing, Feng

    2016-07-01

    We report an all-fiber high power nanosecond pulsed laser at a center wavelength of 1064 nm. Optimizing the coiling diameter of the active fiber, 188 W average power is achieved at a repetition rate of 40 kHz. The pulse width is measured as 101 ns, while the peak power can be estimated to 46.5 kW.

  3. Production of a large-diameter uniform plasma by electron cyclotron resonance heating with a small-diameter Lisitano coil

    NASA Astrophysics Data System (ADS)

    Komori, A.; Takada, Y.; Yonesu, A.; Kawai, Y.

    1991-02-01

    A large-diameter uniform plasma is produced by electron cyclotron resonance heating with a slotted Lisitano coil of 9 cm in diameter by locating the resonance apart from the Lisitano coil. Although the plasma production with a Lisitano coil has been performed extensively by placing the resonance near the Lisitano coil, the influence of the resonance location has not received as much attention. When the resonance is located further than 8 cm from the Lisitano coil, the uniform plasma of ˜40 cm in diameter at densities of ˜1.2×1011 cm-3 is produced over the vacuum chamber with an inner radius of 46 cm. The microwave is propagated in the whole space between the resonance and the Lisitano coil, and spatial electric-field distributions of the microwave play an important role on forming the radially uniform plasma.

  4. CoPt/CeO2 catalysts for the growth of narrow diameter semiconducting single-walled carbon nanotubes.

    PubMed

    Tang, Lei; Li, Taotao; Li, Chaowei; Ling, Lin; Zhang, Kai; Yao, Yagang

    2015-12-14

    For the application of single-walled carbon nanotubes (SWNTs) in nanoelectronic devices, effective techniques for the growth of semiconducting SWNTs (s-SWNTs) with a specific diameter are still a great challenge. Herein, we report a facile strategy for the selective growth of narrow diameter distributed s-SWNTs using CoPt/CeO2 catalysts. The addition of Pt into a Co catalyst dramatically reduces the diameter distributions and even the chirality distributions of the as-grown SWNTs. Oxygen vacancies that are provided by mesoporous CeO2 are responsible for creating an oxidative environment to in situ etch metallic SWNTs (m-SWNTs). Atomic force microscope (AFM) and Raman spectroscopy characterizations indicate a narrow diameter distribution of 1.32 ± 0.03 nm and the selective growth of s-SWNTs to 93%, respectively. In addition, electronic transport measurements also confirm that the Ion/Ioff ratio is mainly in the order of ∼10(3). This work provides an effective strategy for the facile fabrication of narrow diameter distributed s-SWNTs, which will be beneficial to fundamental research and the broad application of SWNTs for future nanoelectronics. PMID:26553394

  5. High-power vertical-cavity surface-emitting laser with an optimized p-contact diameter.

    PubMed

    Zhang, Yan; Ning, Yongqiang; Qin, Li; Wang, Ye; Cui, Jinjiang; Liu, Guangyu; Zhang, Xing; Wang, Zhenfu; Sun, Yanfang; Liu, Yun; Wang, Lijun

    2010-07-01

    A 980 nm bottom-emitting vertical-cavity surface-emitting laser (VCSEL) with a p-contact diameter is reported to achieve high power and good beam quality. A numerical simulation is conducted on the current spreading in a VCSEL with oxidation between the active region and the p-type distributed Bragg reflector. It is found that, for a particular oxide aperture diameter, somewhat homogeneous current distribution can be achieved for a VCSEL with an optimized p-contact diameter. The far-field divergence angle from a 600 microm diameter VCSEL is suppressed from 30 degrees to 15 degrees, and no strong sidelobe is observed in the far-field pattern by using the optimized p-contact diameter. There is a slight rise in threshold and optical output power that is due to the p-contact optimization. By improving the device packaging method, the maximum optical output power of the device is 2.01 W. PMID:20648149

  6. Real-time precision measuring device of tree diameter growth

    NASA Astrophysics Data System (ADS)

    Guo, Mingming; Chen, Aijun; Li, Dongsheng; Liu, Nan; Yao, Jingyuan

    2016-01-01

    DBH(diameter at breast height) is an important factor to reflect of the quality of plant growth, also an important parameter indispensable in forest resources inventory and forest carbon sink, the accurate measurement of DBH or not is directly related to the research of forest resources inventory and forest carbon sink. In this paper, the principle and the mathematical model of DBH measurement device were introduced, the fixture measuring device and the hardware circuit for this tree diameter were designed, the measurement software programs were compiled, and the precision measuring device of tree diameter growth was developed. Some experiments with Australia fir were conducted. Based on experiment data, the correlations among the DBH variation of Australian fir, the environment temperature, air humility and PAR(photosynthetically active radiation) were obtained. The effects of environmental parameters (environment temperature, air humility and PAR) on tree diameter were analyzed. Experimental results show that there is a positive correlation between DBH variation of Australian fir and environment temperature, a negative correlation between DBH variation of Australian fir and air humility , so is PAR.

  7. Solar diameter measurements for study of Sun climate coupling

    NASA Technical Reports Server (NTRS)

    Hill, H. A.

    1983-01-01

    Changes in solar shape and diameter were detected as a possible probe of variability in solar luminosity, an important climatic driving function. A technique was designed which will allow the calibration of the telescope field, providing a scale for long-term comparison of these and future measurements.

  8. Decrease rate of the renal diameter in chronic hemodialysis patients.

    PubMed

    Aoyagi, Teiichiro; Tachibana, Masaaki; Naganuma, Shinji

    2013-01-01

    We here present the results of ultrasonographic (US) evaluations on the alteration of renal diameter of chronic HD patients. Of 109 outpatient HD patients who had neither severe acquired cystic disease of the kidney nor hereditary polycystic kidney disease, we performed US two or three times to measure their maximum renal diameter (mean of both kidneys), and the yearly alteration rate was calculated. The average interval of the two measurements was 35.9 months, and the average HD duration from the HD induction to the first measurement was 29.5 months. The average decrease rate of renal diameter was 4.34 ± 0.4 (SE) mm/year. No statistical difference was seen on the decrease rate in relation to gender, age and original disease (among three groups, glomerulonephritis and IgA nephropathy, diabetes, and others including hypertension). However, the decrease rate was large when the first measurement was close to the induction of hemodialysis, suggesting that the alteration rate reduced according to the hemodialysis vintage (5.3 ± 0.8 mm/year, first measurement not more than 10 months after induction of HD and 1.5 ± 1.6 mm/year, first measurement more than 80 months after induction of HD). Renal diameter decreased approximately 4.3 mm each year, and the decrease rate slowed as the length of time on dialysis increased. PMID:24967236

  9. Rowlinson’s concept of an effective hard sphere diameter

    PubMed Central

    Henderson, Douglas

    2010-01-01

    Attention is drawn to John Rowlinson’s idea that the repulsive portion of the intermolecular interaction may be replaced by a temperature-dependent hard sphere diameter. It is this approximation that made the development of perturbation theory possible for realistic fluids whose intermolecular interactions have a steep, but finite, repulsion at short separations. PMID:20953320

  10. Measuring the Diameter of a Hair with a Steel Rule.

    ERIC Educational Resources Information Center

    Macdonald, John; O'Leary, Sean V.

    1994-01-01

    Describes a technique that uses a helium neon laser, a steel rule, a wooden rule, and a piece of paper to measure the diameter of a hair using the diffraction of light. Details on technique, mathematics, and sources of error are provided. (DDR)

  11. Ratio of Spleen Diameter to Red Blood Cell Distribution Width

    PubMed Central

    Balaban, Daniel Vasile; Popp, Alina; Lungu, Andrei Marian; Costache, Raluca Simona; Anca, Ioana Alina; Jinga, Mariana

    2015-01-01

    Abstract Celiac disease (CD) is currently considerably underdiagnosed, setting the need for developing tools to select patients with probability of CD, who warrant further testing. Red blood cell distribution width (RDW) has been shown in previous studies to be a sensitive predictor for CD, but it lacks specificity. Splenic hypotrophy is also noted frequently in celiac patients. Our aim was to evaluate if spleen diameter to RDW ratio can be used as an indicator for CD. We evaluated 15 newly diagnosed CD patients, 52 patients with inflammatory bowel disease, and 35 patients with irritable bowel syndrome (IBS). We evaluated the differences in spleen diameter, RDW, and their ratio among the four groups. Two-thirds of the CD patients had elevated RDW, compared to 9% in the IBS group. A small spleen was seen in 80% of the celiacs, compared to 21.9% in the ulcerative colitis group, 10% in the Crohn disease group, and 9% in the IBS group. A spleen diameter to RDW ratio under 6 had a sensitivity of 73.3% and specificity of 88.5% in predicting CD, with an AUROC of 0.737. Spleen diameter to RDW ratio is a simple, widely available score, which can be used to select adult patients with probability of CD. PMID:25881851

  12. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  13. Combined position and diameter measures for lunar craters

    USGS Publications Warehouse

    Arthur, D.W.G.

    1977-01-01

    The note addresses the problem of simultaneously measuring positions and diameters of circular impact craters on wide-angle photographs of approximately spherical planets such as the Moon and Mercury. The method allows for situations in which the camera is not aligned on the planet's center. ?? 1977.

  14. Assessment of vessel diameters for MR brain angiography processed images

    NASA Astrophysics Data System (ADS)

    Moraru, Luminita; Obreja, Cristian-Dragos; Moldovanu, Simona

    2015-12-01

    The motivation was to develop an assessment method to measure (in)visible differences between the original and the processed images in MR brain angiography as a method of evaluation of the status of the vessel segments (i.e. the existence of the occlusion or intracerebral vessels damaged as aneurysms). Generally, the image quality is limited, so we improve the performance of the evaluation through digital image processing. The goal is to determine the best processing method that allows an accurate assessment of patients with cerebrovascular diseases. A total of 10 MR brain angiography images were processed by the following techniques: histogram equalization, Wiener filter, linear contrast adjustment, contrastlimited adaptive histogram equalization, bias correction and Marr-Hildreth filter. Each original image and their processed images were analyzed into the stacking procedure so that the same vessel and its corresponding diameter have been measured. Original and processed images were evaluated by measuring the vessel diameter (in pixels) on an established direction and for the precise anatomic location. The vessel diameter is calculated using the plugin ImageJ. Mean diameter measurements differ significantly across the same segment and for different processing techniques. The best results are provided by the Wiener filter and linear contrast adjustment methods and the worst by Marr-Hildreth filter.

  15. Estimating Tree Height-Diameter Models with the Bayesian Method

    PubMed Central

    Duan, Aiguo; Zhang, Jianguo; Xiang, Congwei

    2014-01-01

    Six candidate height-diameter models were used to analyze the height-diameter relationships. The common methods for estimating the height-diameter models have taken the classical (frequentist) approach based on the frequency interpretation of probability, for example, the nonlinear least squares method (NLS) and the maximum likelihood method (ML). The Bayesian method has an exclusive advantage compared with classical method that the parameters to be estimated are regarded as random variables. In this study, the classical and Bayesian methods were used to estimate six height-diameter models, respectively. Both the classical method and Bayesian method showed that the Weibull model was the “best” model using data1. In addition, based on the Weibull model, data2 was used for comparing Bayesian method with informative priors with uninformative priors and classical method. The results showed that the improvement in prediction accuracy with Bayesian method led to narrower confidence bands of predicted value in comparison to that for the classical method, and the credible bands of parameters with informative priors were also narrower than uninformative priors and classical method. The estimated posterior distributions for parameters can be set as new priors in estimating the parameters using data2. PMID:24711733

  16. General view of outside diameter welding stations of the saw ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of outside diameter welding stations of the saw line in bay 8 of the main pipe mill building looking northwest. - U.S. Steel National Tube Works, Main Pipe Mill Building, Along Monongahela River, McKeesport, Allegheny County, PA

  17. 5. 30 DIAMETER ACCESS MANHOLE IN THE CENTER OF THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. 30 DIAMETER ACCESS MANHOLE IN THE CENTER OF THE GATE HOUSE, LOOKING SOUTH. - Washington Water Power Spokane River Upper Falls Hydroelectric Development, Gates & Gate-Lifting Mechanisms, Spokane River, approximately 0.5 mile northeast of intersection of Spokane Falls Boulevard & Post Street, Spokane, Spokane County, WA

  18. Non-Contact EDDY Current Hole Eccentricity and Diameter Measurement

    NASA Technical Reports Server (NTRS)

    Chern, E. James

    1998-01-01

    Precision holes are among the most critical features of a mechanical component. Deviations from permissible tolerances can impede operation and result in unexpected failure. We have developed an automated non-contact eddy current hole diameter and eccentricity measuring system. The operating principle is based on the eddy current lift-off effect, which is the coil impedance as a function of the distance between the coil and the test object. An absolute eddy current probe rotates in the hole. The impedance of each angular position is acquired and input to the computer for integration and analysis. The eccentricity of the hole is the profile of the impedance as a function of angular position as compared to a straight line, an ideal hole. The diameter of the hole is the sum of the diameter of the probe and twice the distance-calibrated impedance. An eddy current image is generated by integrating angular scans for a plurality of depths between the top and bottom to display the eccentricity profile. This system can also detect and image defects in the hole. The method for non-contact eddy current hole diameter and eccentricity measurement has been granted a patent by the U.S. Patent and Trademark Office.

  19. View of wood stave penstocks (four feet in diameter) with ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of wood stave penstocks (four feet in diameter) with steel bands, wood and steel frames; standing on top of penstocks is Doug Hamilton (right), Nooksack Falls hydro-plant operator for puget power, and Ken Rose (left) HAER Historian. - Nooksack Falls Hydroelectric Plant, Route 542, Glacier, Whatcom County, WA

  20. Minimum tube diameters for steady propagation of gaseous detonations

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Ng, H. D.; Lee, J. H. S.

    2014-07-01

    Recent experimental results on detonation limits are reported in this paper. A parametric study was carried out to determine the minimum tube diameters for steady detonation propagation in five different hydrocarbon fuel-oxygen combustible mixtures and in five polycarbonate test tube diameters ranging from 50.8 mm down to a small scale of 1.5 mm. The wave propagation in the tube was monitored by optical fibers. By decreasing the initial pressure, hence the sensitivity of the mixture, the onset of limits is indicated by an abrupt drop in the steady detonation velocity after a short distance of travel. From the measured wave velocities inside the test tube, the critical pressure corresponding to the limit and the minimum tube diameters for the propagation of the detonation can be obtained. The present experimental results are in good agreement with previous studies and show that the measured minimum tube diameters can be reasonably estimated on the basis of the /3 rule over a wide range of conditions, where is the detonation cell size. These new data shall be useful for safety assessment in process industries and in developing and validating models for detonation limits.

  1. Downhole pumps for water sampling in small diameter wells

    USGS Publications Warehouse

    Koopman, F. C.

    1979-01-01

    The relatively high cost and difficulty in locating a source of pumps for use in obtaining ground-water samples from small-diameter wells has demonstrated a need for this report. Criteria for selection of a pump and pumping equipment to meet specific requirements has been tabulated to assist field personnel in making a selection from commercial sources. (Kosco-USGS)

  2. Estimating tree height-diameter models with the Bayesian method.

    PubMed

    Zhang, Xiongqing; Duan, Aiguo; Zhang, Jianguo; Xiang, Congwei

    2014-01-01

    Six candidate height-diameter models were used to analyze the height-diameter relationships. The common methods for estimating the height-diameter models have taken the classical (frequentist) approach based on the frequency interpretation of probability, for example, the nonlinear least squares method (NLS) and the maximum likelihood method (ML). The Bayesian method has an exclusive advantage compared with classical method that the parameters to be estimated are regarded as random variables. In this study, the classical and Bayesian methods were used to estimate six height-diameter models, respectively. Both the classical method and Bayesian method showed that the Weibull model was the "best" model using data1. In addition, based on the Weibull model, data2 was used for comparing Bayesian method with informative priors with uninformative priors and classical method. The results showed that the improvement in prediction accuracy with Bayesian method led to narrower confidence bands of predicted value in comparison to that for the classical method, and the credible bands of parameters with informative priors were also narrower than uninformative priors and classical method. The estimated posterior distributions for parameters can be set as new priors in estimating the parameters using data2. PMID:24711733

  3. Continuous measurement of vascular diameters via television microscopy.

    PubMed

    Devaney, M J; Rathke, J E; Bartel, R W; Mcdonald, J E; Wiegman, D L; Miller, F N; Harris, P D

    1976-01-01

    In the past 10 years, microcirculation studies have emphasized quantitative measurements of microvascular diameters to characterize in vivo small vessel responses to experimental forcings such as hemorrhage, anesthesia, and hypoxia. We have developed an instrument to obtain continuous diameter measurements of a small artery and vein (40-200 mu) via closed-circuit television microscopy. The outputs are analog voltages proportional to the vessel diameters. Video processing is limited to two image areas termed "windows," which are defined by markers on the monitor and positioned over separate vertically aligned vessels. Each vessel, which appears darker than the surrounding tissue, is located by comparing the video signal to a reference voltage that adapts to changes in the relative contrast within the window. In the presence of a vessel, a ramp voltage is generated, the peak value of which is proportional to the vessel diameter. These peaks are averaged over the 15-video lines of the window and over several video frames to reduce noise sensitivity. In order to accommodate preparation movement such as skeletal muscle contraction, window position and width automatically adapt to changes in vessel position and width. Visual verification of system performance is provided by clamping the video signal to white on that portion of the image which the instrument identifies as vessel. PMID:950283

  4. Genetic and Environmental Effects on the Abdominal Aortic Diameter Development

    PubMed Central

    Tarnoki, Adam Domonkos; Tarnoki, David Laszlo; Littvay, Levente; Garami, Zsolt; Karlinger, Kinga; Berczi, Viktor

    2016-01-01

    Background Configuration of the abdominal aorta is related to healthy aging and a variety of disorders. Objectives We aimed to assess heritable and environmental effects on the abdominal aortic diameter. Methods 114 adult (69 monozygotic, 45 same-sex dizygotic) twin pairs (mean age 43.6 ± 16.3 years) underwent abdominal ultrasound with Esaote MyLab 70X ultrasound machine to visualize the abdominal aorta below the level of the origin of the renal arteries and 1-3 cm above the bifurcation. Results Age- and sex-adjusted heritability of the abdominal aortic diameter below the level of the origin of the renal arteries was 40% [95% confidence interval (CI), 14 to 67%] and 55% above the aortic bifurcation (95% CI, 45 to 70%). None of the aortic diameters showed common environmental effects, but unshared environmental effects were responsible for 60% and 45% of the traits, respectively. Conclusions Our analysis documents the moderate heritability and its segment-specific difference of the abdominal aortic diameter. The moderate part of variance was explained by unshared environmental components, emphasizing the importance of lifestyle factors in primary prevention. Further studies in this field may guide future gene-mapping efforts and investigate specific lifestyle factors to prevent abdominal aortic dilatation and its complications. PMID:26559855

  5. Facile Synthesis of Sub-20 nm Silver Nanowires through a Bromide-Mediated Polyol Method.

    PubMed

    da Silva, Robson Rosa; Yang, Miaoxin; Choi, Sang-Il; Chi, Miaofang; Luo, Ming; Zhang, Chao; Li, Zhi-Yuan; Camargo, Pedro H C; Ribeiro, Sidney José Lima; Xia, Younan

    2016-08-23

    Essentially all of the Ag nanowires reported in the literature have sizes larger than 30 nm in diameter. In this article, we report a simple and robust approach to the synthesis of Ag nanowires with diameters below 20 nm and aspect ratios over 1000 using a one-pot polyol method. The Ag nanowires took a penta-twinned structure, and they could be obtained rapidly (<35 min) and in high morphology purity (>85% of the as-obtained solid product) under atmospheric pressure. The key to the success of this synthesis is to restrain the nanowires from lateral growth by employing both Br(-) ions and poly(vinylpyrrolidone) with a high molecular weight of 1 300 000 g/mol to cap the {100} side faces, together with the use of a syringe pump to slowly introduce AgNO3 into the reaction solution. By optimizing the ratios between the capping agents and AgNO3, we were able to slow down the reduction kinetics and effectively direct the Ag nanowires to grow along the longitudinal direction only. The nanowires showed great mechanical flexibility and could be bent with acute angles without breaking. Because of their small diameters, the transverse localized surface plasmon resonance peak of the Ag nanowires could be pushed down to the ultraviolet region, below 400 nm, making them ideal conductive elements for the fabrication of touch screens, solar cells, and smart windows. PMID:27483165

  6. Radiation Tolerance of 65nm CMOS Transistors

    DOE PAGESBeta

    Krohn, M.; Bentele, B.; Christian, D. C.; Cumalat, J. P.; Deptuch, G.; Fahim, F.; Hoff, J.; Shenai, A.; Wagner, S. R.

    2015-12-11

    We report on the effects of ionizing radiation on 65 nm CMOS transistors held at approximately -20°C during irradiation. The pattern of damage observed after a total dose of 1 Grad is similar to damage reported in room temperature exposures, but we observe less damage than was observed at room temperature.

  7. Negative-tone 193-nm resists

    NASA Astrophysics Data System (ADS)

    Cho, Sungseo; Vander Heyden, Anthony; Byers, Jeff D.; Willson, C. Grant

    2000-06-01

    A great deal of progress has been made in the design of single layer positive tone resists for 193 nm lithography. Commercial samples of such materials are now available from many vendors. The patterning of certain levels of devices profits from the use of negative tone resists. There have been several reports of work directed toward the design of negative tones resists for 193 nm exposure but, none have performed as well as the positive tone systems. Polymers with alicyclic structures in the backbone have emerged as excellent platforms from which to design positive tone resists for 193 nm exposure. We now report the adaptation of this class of polymers to the design of high performance negative tone 193 nm resists. New systems have been prepared that are based on a polarity switch mechanism for modulation of the dissolution rate. The systems are based on a polar, alicyclic polymer backbone that includes a monomer bearing a glycol pendant group that undergoes the acid catalyzed pinacol rearrangement upon exposure and bake to produce the corresponding less polar ketone. This monomer was copolymerized with maleic anhydride and a norbornene bearing a bis-trifluoromethylcarbinol. The rearrangement of the copolymer was monitored by FT-IR as a function of temperature. The synthesis of the norbornene monomers will be presented together with characterization of copolymers of these monomers with maleic anhydride. The lithographic performance of the new resist system will also be presented.

  8. White Sands, Carrizozo Lava Beds, NM

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A truly remarkable view of White Sands and the nearby Carrizozo Lava Beds in southeast NM (33.5N, 106.5W). White Sands, site of the WW II atomic bomb development and testing facility and later post war nuclear weapons testing that can still be seen in the cleared circular patterns on the ground.

  9. Nuclear criticality safety calculational analysis for small-diameter containers

    SciTech Connect

    LeTellier, M.S.; Smallwood, D.J.; Henkel, J.A.

    1995-11-01

    This report documents calculations performed to establish a technical basis for the nuclear criticality safety of favorable geometry containers, sometimes referred to as 5-inch containers, in use at the Portsmouth Gaseous Diffusion Plant. A list of containers currently used in the plant is shown in Table 1.0-1. These containers are currently used throughout the plant with no mass limits. The use of containers with geometries or material types other than those addressed in this evaluation must be bounded by this analysis or have an additional analysis performed. The following five basic container geometries were modeled and bound all container geometries in Table 1.0-1: (1) 4.32-inch-diameter by 50-inch-high polyethylene bottle; (2) 5.0-inch-diameter by 24-inch-high polyethylene bottle; (3) 5.25-inch-diameter by 24-inch-high steel can ({open_quotes}F-can{close_quotes}); (4) 5.25-inch-diameter by 15-inch-high steel can ({open_quotes}Z-can{close_quotes}); and (5) 5.0-inch-diameter by 9-inch-high polybottle ({open_quotes}CO-4{close_quotes}). Each container type is evaluated using five basic reflection and interaction models that include single containers and multiple containers in normal and in credible abnormal conditions. The uranium materials evaluated are UO{sub 2}F{sub 2}+H{sub 2}O and UF{sub 4}+oil materials at 100% and 10% enrichments and U{sub 3}O{sub 8}, and H{sub 2}O at 100% enrichment. The design basis safe criticality limit for the Portsmouth facility is k{sub eff} + 2{sigma} < 0.95. The KENO study results may be used as the basis for evaluating general use of these containers in the plant.

  10. Changes in retinal microvascular diameter in patients with diabetes

    PubMed Central

    da Silva, Andréa Vasconcellos Batista; Gouvea, Sonia Alves; da Silva, Aurélio Paulo Batista; Bortolon, Saulo; Rodrigues, Anabel Nunes; Abreu, Glaucia Rodrigues; Herkenhoff, Fernando Luiz

    2015-01-01

    Background and objectives Diabetic retinopathy is the main microvascular complication in diabetes mellitus and needs to be diagnosed early to prevent severe sight-threatening retinopathy. The purpose of this study was to quantify the retinal microvasculature pattern and analyze the influence of blood glucose level and the duration of diabetes mellitus on the retinal microvasculature. Methods Two groups were analyzed: patients with diabetes (N=26) and patients without diabetes, ie, controls (N=26). A quantitative semiautomated method analyzed retinal microvasculature. The diameters of arterioles and venules were measured. The total numbers of arterioles and venules were counted. The ratio of arteriole diameter to venule diameter was calculated. The retinal microvasculature pattern was related to clinical and biochemical parameters. Results Patients with diabetes exhibited larger venule diameters in the upper temporal quadrant of the retina compared to the lower temporal quadrant (124.85±38.03 µm vs 102.92±15.69 µm; P<0.01). Patients with diabetes for 5 or more years had larger venule diameters in the upper temporal quadrant than patients without diabetes (141.62±44.44 vs 112.58±32.11 µm; P<0.05). The degree of venodilation in the upper temporal quadrant was positively correlated with blood glucose level and the estimated duration of diabetes mellitus. Interpretation and conclusion The employed quantitative method demonstrated that patients with diabetes exhibited venule dilation in the upper temporal quadrant, and the duration of diabetes mellitus was positively correlated with blood glucose level. Therefore, the early assessment of retinal microvascular changes is possible prior to the onset of diabetic retinopathy. PMID:26345217

  11. Conductive Atomic Force Microscopy Analysis of Sub-30 nm Magnetic Tunnel Junction Nanopillars

    NASA Astrophysics Data System (ADS)

    Evarts, Eric R.

    2011-12-01

    At the nanoscale, physical processes can be found that do not have a macroscopic counterpart. The electrical manipulation of nanomagnets is an example of one such process that has no measurable effect in structures larger than a few micrometers. For nanomagnets less than 50 nm across, there was no existing technique that could reliably detect and manipulate these nanomagnets. I present here a conductive atomic force microscopy (CAFM) technique that can deliver greater than 10 mA of current to a magnetic nanopillar as small as 10 nm in diameter. Using magnetic tunnel junction (MTJ) nanopillars with two thin ferromagnetic layers separated by a thin insulator, two different electrical resistances are measured for the parallel and antiparallel relative magnetic orientations. Using this technique, I demonstrated spin torque transfer (STT) switching of MTJ nanopillars. Using nanoparticle masking, I fabricated smaller MTJ nanopillars than previously reported. These 26 nm diameter MTJ nanopillars showed an increased switching current density of 10 × 10 6 A/cm2 compared to the 1-3 × 106 A/cm2 observed on 200 nm × 100 nm nanopillars. As these small nanopillars were cycled multiple times, the electrical and magnetic properties changed showing a decrease in the ΔR between the two states and an overall increase in the resistance indicating a shrinking effective nanopillar diameter due to oxidation. The low frequency noise power spectrum was recorded as a function of applied current density. These spectra indicate a small magnetic noise component that depends on the STT effect that can be suppressed with an applied magnetic field.

  12. Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

    SciTech Connect

    Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Jiang, H.; Kauppinen, E. I.; Susi, T.; Nasibulin, A. G.

    2015-07-06

    We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3–4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ∼10{sup 5 }cm{sup −3} prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

  13. Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

    NASA Astrophysics Data System (ADS)

    Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Susi, T.; Jiang, H.; Nasibulin, A. G.; Kauppinen, E. I.

    2015-07-01

    We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3-4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ˜105 cm-3 prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

  14. VizieR Online Data Catalog: Thorium spectrum from 250nm to 5500nm (Redman+, 2014)

    NASA Astrophysics Data System (ADS)

    Redman, S. L.; Nave, G.; Sansonetti, C. J.

    2014-04-01

    We observed the spectrum of a commercial sealed Th/Ar HCL running at 25mA for almost 15hr starting on 2011 November 2. The region of observation was limited to between 8500/cm and 28000/cm (360nm and 1200nm) by the sensitivity of the silicon photodiode detector. (5 data files).

  15. A photodegradable hexaaza-pentacene molecule for selective dispersion of large-diameter semiconducting carbon nanotubes.

    PubMed

    Han, Jie; Ji, Qiyan; Li, Hongbo; Li, Gang; Qiu, Song; Li, Hai-Bei; Zhang, Qichun; Jin, Hehua; Li, Qingwen; Zhang, Jin

    2016-06-01

    Harvesting high-purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with removable dispersants remains a challenge. In this work, we demonstrate that small heteroacene derivatives may serve as promising selective dispersants for sorting s-SWCNTs. A rich N "doped" and thiophene-substituted hexaazapentacene molecule, denoted as 4HP, was found to be more favorable for high-purity s-SWCNTs with large diameters. Importantly, 4HP is photodegradable under 365 nm or blue light, which enables a simple deposition approach for the formation of clean s-SWCNT networks. The as-fabricated thin film transistors show excellent performance with a charge-mobility of 30-80 cm(2) V(-1) s(-1) and an on-off ratio of 10(4)-10(6). PMID:27230421

  16. Optical properties of plastically bent large-diameter sapphire fiber tips for laser tissue ablations

    NASA Astrophysics Data System (ADS)

    Tong, Limin

    2000-10-01

    Aiming to facilitate laser surgery applications, six 0.75mm- diameter 90mm-length sapphire fiber tips were plastically bent by means of CO2 lasers with bending radii from 1.7mm to 3.6mm and bending angles of 15-120 degree(s). The average bending loss caused by the bending process of the tips is about 0.03dB with the minimum loss less than 0.02dB, the damage thresholds of these tips are higher than 160MW/cm2 for Nd:YAG laser pulses at 1.06micrometers and 2MW/cm2 for CuBr laser pulses at 510.6nm. Satisfactory optical properties of these sapphire fiber tips show that they are promising for use in laser surgery applications such as tissue ablations. 16

  17. Submicron-diameter phase-separated scintillator fibers for high-resolution X-ray imaging

    NASA Astrophysics Data System (ADS)

    Ohashi, Yoshihiro; Yasui, Nobuhiro; Yokota, Yuui; Yoshikawa, Akira; Den, Toru

    2013-02-01

    We demonstrated micrometer-scale resolution X-ray imaging by using phase-separated scintillator fibers. Hexagonally well-aligned 680-nm-diameter GdAlO3(GAP):Ce3+ scintillator fibers surrounded with α-Al2O3 were fabricated from directionally solidified eutectics. The GAP:Ce3+ fibers convert X-rays to lights and emitted lights are confined and transported along the fiber direction by a total reflection mode. High-resolution X-ray image of a gold grating phantom with a 4 μm aperture, corresponding to a bundle of 12 fibers, was achieved even with a 150 -μm-thick scintillator. These scintillator fibers overcome resolution reduction caused by light scattering and almost reach the resolution limit of the material nature itself.

  18. Synthesis and growth mechanism of long ultrafine gold nanowires with uniform diameter

    NASA Astrophysics Data System (ADS)

    Kura, Hiroaki; Ogawa, Tomoyuki

    2010-04-01

    Homogeneous Au nanowires with 1.5 nm diameters and lengths of over 100 μm were synthesized in an oleylamine matrix via the simple reduction of aurichloride in a limited reaction temperature range around 85 °C. Oleylamine has multifunctional roles as solvent, surfactant, and reductant, and the surfactant induce anisotropic growth by adsorbing on the specific Au crystalline surface. As a result, Au nanowires were grown along the ⟨111⟩ direction of fcc-Au having many hcp atomic stacks. In this synthesis method, various shapes of Au nanostructures were produced simultaneously and this was strongly dependent on the reaction temperature. Au nanowires were provided by reconstruction from nanoparticles or their agglomeration. The growth mechanism of the Au nanowire in this synthesis was found to be quite unique and different from that for a conventional one-dimensional nanostructure which is obtained by anisotropical growth with supplying atoms from external resources.

  19. Ion Exclusion by Sub 2-nm Carbon Nanotube Pores

    SciTech Connect

    Fornasiero, F; Park, H G; Holt, J K; Stadermann, M; Grigoropoulos, C P; Noy, A; Bakajin, O

    2008-04-09

    Carbon nanotubes offer an outstanding platform for studying molecular transport at nanoscale, and have become promising materials for nanofluidics and membrane technology due to their unique combination of physical, chemical, mechanical, and electronic properties. In particular, both simulations and experiments have proved that fluid flow through carbon nanotubes of nanometer size diameter is exceptionally fast compared to what continuum hydrodynamic theories would predict when applied on this length scale, and also, compared to conventional membranes with pores of similar size, such as zeolites. For a variety of applications such as separation technology, molecular sensing, drug delivery, and biomimetics, selectivity is required together with fast flow. In particular, for water desalination, coupling the enhancement of the water flux with selective ion transport could drastically reduce the cost of brackish and seawater desalting. In this work, we study the ion selectivity of membranes made of aligned double-walled carbon nanotubes with sub-2 nm diameter. Negatively charged groups are introduced at the opening of the carbon nanotubes by oxygen plasma treatment. Reverse osmosis experiments coupled with capillary electrophoresis analysis of permeate and feed show significant anion and cation rejection. Ion exclusion declines by increasing ionic strength (concentration) of the feed and by lowering solution pH; also, the highest rejection is observed for the A{sub m}{sup Z{sub A}} C{sub n}{sup Z{sub C}} salts (A=anion, C=cation, z= valence) with the greatest Z{sub A}/Z{sub C} ratio. Our results strongly support a Donnan-type rejection mechanism, dominated by electrostatic interactions between fixed membrane charges and mobile ions, while steric and hydrodynamic effects appear to be less important. Comparison with commercial nanofiltration membranes for water softening reveals that our carbon nanotube membranes provides far superior water fluxes for similar ion

  20. Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy

    PubMed Central

    Chen, Y. T.; Karlsson, K. F.; Birch, J.; Holtz, P. O.

    2016-01-01

    Direct measurements of carrier diffusion in GaN nanorods with a designed InGaN/GaN layer-in-a-wire structure by scanning near-field optical microscopy (SNOM) were performed at liquid-helium temperatures of 10 K. Without an applied voltage, intrinsic diffusion lengths of photo-excited carriers were measured as the diameters of the nanorods differ from 50 to 800 nm. The critical diameter of nanorods for carrier diffusion is concluded as 170 nm with a statistical approach. Photoluminescence spectra were acquired for different positions of the SNOM tip on the nanorod, corresponding to the origins of the well-defined luminescence peaks, each being related to recombination-centers. The phenomenon originated from surface oxide by direct comparison of two nanorods with similar diameters in a single map has been observed and investigated. PMID:26876009

  1. Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Y. T.; Karlsson, K. F.; Birch, J.; Holtz, P. O.

    2016-02-01

    Direct measurements of carrier diffusion in GaN nanorods with a designed InGaN/GaN layer-in-a-wire structure by scanning near-field optical microscopy (SNOM) were performed at liquid-helium temperatures of 10 K. Without an applied voltage, intrinsic diffusion lengths of photo-excited carriers were measured as the diameters of the nanorods differ from 50 to 800 nm. The critical diameter of nanorods for carrier diffusion is concluded as 170 nm with a statistical approach. Photoluminescence spectra were acquired for different positions of the SNOM tip on the nanorod, corresponding to the origins of the well-defined luminescence peaks, each being related to recombination-centers. The phenomenon originated from surface oxide by direct comparison of two nanorods with similar diameters in a single map has been observed and investigated.

  2. Monte-Carlo simulation studies of the effect of temperature and diameter variation on spin transport in II-VI semiconductor nanowires

    NASA Astrophysics Data System (ADS)

    Chishti, Sabiq; Ghosh, Bahniman; Bishnoi, Bhupesh

    2015-02-01

    We have analyzed the spin transport behaviour of four II-VI semiconductor nanowires by simulating spin polarized transport using a semi-classical Monte-Carlo approach. The different scattering mechanisms considered are acoustic phonon scattering, surface roughness scattering, polar optical phonon scattering, and spin flip scattering. The II-VI materials used in our study are CdS, CdSe, ZnO and ZnS. The spin transport behaviour is first studied by varying the temperature (4-500 K) at a fixed diameter of 10 nm and also by varying the diameter (8-12 nm) at a fixed temperature of 300 K. For II-VI compounds, the dominant mechanism is for spin relaxation; D'yakonovPerel and Elliot Yafet have been actively employed in the first order model to simulate the spin transport. The dependence of the spin relaxation length (SRL) on the diameter and temperature has been analyzed.

  3. Synthesis and electrochemistry of 6 nm ferrocenated indium-tin oxide nanoparticles.

    PubMed

    Roberts, Joseph J P; Vuong, Kim T; Murray, Royce W

    2013-01-01

    Indium-tin oxide (ITO) nanoparticles, 6.1 ± 0.8 nm in diameter, were synthesized using a hot injection method. After reaction with 3-aminopropyldimethylethoxysilane to replace the initial oleylamine and oleic acid capping ligands, the aminated nanoparticles were rendered electroactive by functionalization with ferrocenoyl chloride. The nanoparticle color changed from blue-green to light brown, and the nanoparticles became more soluble in polar solvents, notably acetonitrile. The nanoparticle diffusion coefficient (D = 1.0 × 10(-6) cm(2)/s) and effective ferrocene concentration (C = 0.60 mM) in acetonitrile solutions were determined using ratios of DC and D(1/2)C data measured by microdisk voltammetry and chronoamperometry. The D result compares favorably to an Einstein-Stokes estimate (2.1 × 10(-6) cm(2)/s), assuming an 8 nm hydrodynamic diameter in acetonitrile (6 nm for the ITO core plus 2 nm for the ligand shell). The ferrocene concentration result is lower than anticipated (ca. 1.60 mM) based on a potentiometric titration of the ferrocene sites with Cu(II) in acetonitrile. Cyclic voltammetric data indicate tendency of the ferrocenated nanoparticles to adsorb on the Pt working electrode. PMID:23267676

  4. The effect of beam diameter on the electron skirt in a high pressure scanning electron microscope.

    PubMed

    Belkorissat, R; Kadoun, A; Khelifa, B; Mathieu, C

    2004-01-01

    Helium gas and air are commonly used in the high pressure scanning electron microscope (HPSEM). The presence of a gaseous environment in the specimen chamber modifies the electron beam profile. In order to fully understand the beam-gas interaction, we have investigated the beam-diameter effect for two gases (helium and air) by Monte Carlo simulation. In this calculation, we have assumed that the electron beam is Gaussian and we have explored the influence of the nature of the gas at low voltage. When the beam diameter varies between 1 and 100 nm, there is no influence on the beam profile for these two gases. The resolving power of the HPSEM is not affected by the beam-gas interaction. These theoretical results have been compared with experimental images obtained at low voltage under air and helium gases. The variation of image quality at low voltage has confirmed the interest of helium for use in a Field Emission Gun SEM (FEGSEM) in high pressure (or low vacuum) conditions. PMID:15219900

  5. Flux-Dependent Growth Kinetics and Diameter Selectivity in Single-Wall Carbon Nanotube Arrays

    SciTech Connect

    Geohegan, David B; Puretzky, Alexander A; Jackson, Jeremy Joseph; Rouleau, Christopher M; Eres, Gyula; More, Karren Leslie

    2011-01-01

    The nucleation and growth kinetics of single-wall carbon nanotubes in aligned arrays have been measured using fast pulses of acetylene and in situ optical diagnostics in conjunction with low pressure chemical vapor deposition (CVD). Increasing the acetylene partial pressure is shown to decrease nucleation times by three orders of magnitude, permitting aligned nanotube arrays to nucleate and grow to microns lengths within single gas pulses at high (up to 7 micron/s) peak growth rates and short ~ 0.5 s times.Low-frequency Raman scattering (> 10 cm-1) and transmission electron microscopy measurements show that increasing the feedstock flux in both continuous-CVD and pulsed-CVD shifts the product distribution to large single-wall carbon nanotube diameters > 2.5 nm. Sufficiently high acetylene partial pressures in pulsed-CVD appear to temporarily terminate the growth of the fastest- growing, small-diameter nanotubes by overcoating the more catalytically-active, smaller catalyst nanoparticles within the ensemble with non-nanotube carbon in agreement with a growth model. The results indicate that subsets of catalyst nanoparticle ensembles nucleate, grow, and terminate growth within different flux ranges according to their catalytic activity.

  6. Helical magneto-cumulative generator 280 mm in diameter

    NASA Astrophysics Data System (ADS)

    Demidov, V. A.; Kazakov, S. A.; Boriskin, A. S.; Vlasov, Yu. V.; Yanenko, V. A.; Nikolaev, N. I.; Volodchenkov, S. I.

    2015-01-01

    Several possibilities of preamplifier energy and power increasing are considered: using a more powerful (HMX-based) conical HE-charge in the central tube of the magneto-cumulative generator, using a magnetic flux finish pressing out device with axial initiation of the HE charge, and increasing the inner diameter of the helix. A magneto-cumulative generator (MCG) with a helix 280 mm in diameter (MCG-280) is developed. The new preamplifier has a power of ≈400 GW and is able to power a ten-element DMCG480 with an initial inductance of ≈0.2 µH by a current of ≈10 MA with a characteristic current rise time (by a factor of e at the final stage of its operation) τ e = 32 µs.

  7. Angular diameter distances reconsidered in the Newman and Penrose formalism

    NASA Astrophysics Data System (ADS)

    Kling, Thomas P.; Aly, Aly

    2016-02-01

    Using the Newman and Penrose spin coefficient (NP) formalism, we provide a derivation of the Dyer-Roeder equation for the angular diameter distance in cosmological space-times. We show that the geodesic deviation equation written in NP formalism is precisely the Dyer-Roeder equation for a general Friedman-Robertson-Walker (FRW) space-time, and then we examine the angular diameter distance to redshift relation in the case that a flat FRW metric is perturbed by a gravitational potential. We examine the perturbation in the case that the gravitational potential exhibits the properties of a thin gravitational lens, demonstrating how the weak lensing shear and convergence act as source terms for the perturbed Dyer-Roeder equation.

  8. Steering knuckle diameter measurement based on optical 3D scanning

    NASA Astrophysics Data System (ADS)

    Song, Li-mei; Li, Da-peng; Chang, Yu-lan; Xi, Jiang-tao; Guo, Qing-hua

    2014-11-01

    To achieve accurate measurements, the creating a fitting hole for internal diameter (CFHID) measurement method and the establishing multi-sectional curve for external diameter (EMCED) measurement method are proposed in this paper, which are based on computer vision principle and three-dimensional (3D) reconstruction. The methods are able to highlight the 3D characteristics of the scanned object and to achieve the accurate measurement of 3D data. It can create favorable conditions for realizing the reverse design and 3D reconstruction of scanned object. These methods can also be applied to dangerous work environment or the occasion that traditional contact measurement can not meet the demands, and they can improve the security in measurement.

  9. Predicting The Tube Diameter For Polymer Melts and Solutions

    NASA Astrophysics Data System (ADS)

    Milner, Scott

    2005-03-01

    A simple conjecture, relating the tube diameter to a characteristic length called the packing length, works well for all flexible entangled polymer melts. This is a remarkable result, because the tube diameter represents the confining effect of uncrossability of the chains, whereas the packing length is determined only by a chain's bulkiness and flexibility. I extend this conjecture to solutions: first for theta solvents, where it is shown to be equivalent to the Colby-Rubinstein scaling picture, and then for good solvents. In the latter case, it turns out that the number of blobs per entanglement strand is not a constant as had been previously assumed, but depends on the ratio of the packing length to the thermal blob size. Finally, I suggest that the packing length can be related to the Gauss winding number density, thus providing a topological basis for the conjecture.

  10. EFFECT OF PARTICLE DIAMETER ON EXCLUSION-ZONE SIZE

    PubMed Central

    NHAN, D.T.; POLLACK, G.H.

    2011-01-01

    Particles and solutes are excluded from the vicinity of hydrophilic surfaces, leaving large microsphere-free regions known as exclusion zones (EZs). Prior work had indicated that EZs could extend to distances of up to several hundred micrometers from the nucleating surface. These observations were made on large, extended surfaces, leaving open the question whether EZ size might depend on the characteristic dimension of the excluding surface. We placed one or few ion-exchange-resin beads whose diameters varied from 15 μm to 300 μm in cuvettes. The beads were suffused with aqueous microsphere suspensions for observing the surfaces’ exclusionary behavior. Results showed a direct relation between bead size and EZ size over the full range of bead diameter, implying a similar relation for smaller particles or molecules, perhaps extending beyond the resolution of the light microscope. PMID:22389653

  11. Writing 40 nm marks by using a beaked metallic plate near-field optical probe.

    PubMed

    Matsumoto, T; Anzai, Y; Shintani, T; Nakamura, K; Nishida, T

    2006-01-15

    We have developed a near-field optical probe that uses a triangular metallic plate with a three-dimensionally tapered apex as a light source for thermally assisted magnetic recording. Numerical analysis using a finite-element method shows that the size of the optical spot generated at the apex is 15 nm x 20 nm, and the efficiency (defined as the ratio between the power of the optical near field at the surface of the recording medium and that of the incident light) is 15% when the incident light is focused by a lens with a numerical aperture of 0.8. The metallic plate was fabricated on the surface of a quartz slider and used for writing marks on a phase change recording medium. The marks were observed with a scanning electron microscope, and we confirmed that marks with a diameter of 40 nm were successfully written on the medium. PMID:16441049

  12. Laser damage database at 1064 nm

    SciTech Connect

    Rainer, F.; Gonzales, R.P.; Morgan, A.J.

    1990-03-01

    In conjunction with our diversification of laser damage testing capabilities, we have expanded upon a database of threshold measurements and parameter variations at 1064 nm. This includes all tests at low pulse-repetition frequencies (PRF) ranging from single shots to 120 Hz. These tests were conducted on the Reptile laser facility since 1987 and the Variable Pulse Laser (VPL) facility since 1988. Pulse durations ranged from 1 to 16 ns. 10 refs., 14 figs.

  13. Sunlight induced 685 nm fluorescence imagery

    NASA Technical Reports Server (NTRS)

    Kim, Hongsuk H.; Van Der Piepen, Heinz

    1986-01-01

    The capability of a new fluorescence method is evaluated using data from an aircraft fluorescence experiment conducted on the Elbe River on August 10-14, 1981. The technique measures chlorophyll concentrations by monitoring sunlight-induced fluorescence at 685 nm. Upwelling radiance spectra and vertical profiles of upwelling radiances are presented and analyzed. The image-processing algorithm used to retrieve fluorescence signals from raw data is described.

  14. Radiation Status of Sub-65 nm Electronics

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.

    2011-01-01

    Ultra-scaled complementary metal oxide semiconductor (CMOS) includes commercial foundry capabilities at and below the 65 nm technology node Radiation evaluations take place using standard products and test characterization vehicles (memories, logic/latch chains, etc.) NEPP focus is two-fold: (1) Conduct early radiation evaluations to ascertain viability for future NASA missions (i.e. leverage commercial technology development). (2) Uncover gaps in current testing methodologies and mechanism comprehension -- early risk mitigation.

  15. Binary 193nm photomasks aging phenomenon study

    NASA Astrophysics Data System (ADS)

    Dufaye, Félix; Sartelli, Luca; Pogliani, Carlo; Gough, Stuart; Sundermann, Frank; Miyashita, Hiroyuki; Hidenori, Yoshioka; Charras, Nathalie; Brochard, Christophe; Thivolle, Nicolas

    2011-05-01

    193nm binary photomasks are still used in the semiconductor industry for the lithography of some critical layers for the nodes 90nm and 65nm, with high volumes and over long period. These 193nm binary masks seem to be well-known but recent studies have shown surprising degrading effects, like Electric Field induced chromium Migration (EFM) [1] or chromium migration [2] [3] . Phase shift Masks (PSM) or Opaque MoSi On Glass (OMOG) might not be concerned by these effects [4] [6] under certain conditions. In this paper, we will focus our study on two layers gate and metal lines. We will detail the effects of mask aging, with SEM top view pictures revealing a degraded chromium edge profile and TEM chemical analyses demonstrating the growth of a chromium oxide on the sidewall. SEMCD measurements after volume production indicated a modified CD with respect to initial CD data after manufacture. A regression analysis of these CD measurements shows a radial effect, a die effect and an isolated-dense effect. Mask cleaning effectiveness has also been investigated, with sulphate or ozone cleans, to recover the mask quality in terms of CD. In complement, wafer intrafield CD measurements have been performed on the most sensitive structure to monitor the evolution of the aging effect on mask CD uniformity. Mask CD drift have been correlated with exposure dose drift and isolated-dense bias CD drift on wafers. In the end, we will try to propose a physical explanation of this aging phenomenon and a solution to prevent from it occurring.

  16. The diameter and thermal inertia of 433 Eros

    NASA Technical Reports Server (NTRS)

    Morrison, D.

    1976-01-01

    Radiometry of Eros at 10 and 20 micrometers demonstrates that the thermal conductivity of the upper centimeter of the surface is approximately as low as that of the moon, suggesting that the asteroid has a regolith of highly porous rocky material. When combined with photoelectric photometry, these infrared measurements yield an effective diameter of Eros at maximum light of 22 plus or minus 2 km and a geometric albedo of 0.18 plus or minus 0.03.

  17. Cohesive/cohesionless sediment transition diameter from settling velocity data

    NASA Astrophysics Data System (ADS)

    Mehta, Ashish J.; Letter, Joseph V.

    2015-09-01

    Mathematical models designed to simulate the movement of cohesive and cohesionless particles require as input the diameter d T specifying the transition between these two transport modes. As an effort to identify this diameter, Migniot (La Houille Blanche, 7, 591-620, 1968) measured in a water-filled column the settling velocities of flocs and respective deflocculated particles of mainly mineral cohesive sediments. The data were plotted as the ratio of the floc settling velocity to the particle velocity, called the flocculation factor F f , against particle diameter d s . The trend line was found to approximately follow an empirical power-law such that F f increased rapidly as d s decreased below d T estimated to be about 30 μm at F f = 1. Assuming fractal self-similarity among falling flocs, the power-law exponent of 5/3 is shown to correspond to a fractal dimension of 2.65 implying that the flocs were densely packed. The diameter d T depends on the electrochemical properties of the suspended particles as well as the kinetics of floc growth and breakup, hence to an extent on the method of determination of d T . Its value deduced more directly from measurement of the critical shear stress for erosion of flocs at the surface of cohesive sediment beds has been reported to be about 10 μm, which is lower than 30 μm. Among other reasons, it is likely that the difference is rooted in the limited experimental information available as well as difficulty in characterizing the effect of highly graded distributions of the particle settling velocity.

  18. NEOWISE Diameters and Albedos V1.0

    NASA Astrophysics Data System (ADS)

    Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; Nugent, C. R.; Sonnett, S. M.; Stevenson, R. A.; Wright, E. L.

    2016-06-01

    This PDS data set represents a compilation of published diameters, optical albedos, near-infrared albedos, and beaming parameters for minor planets detected by NEOWISE during the fully cryogenic, 3-band cryo, post-cryo and NEOWISE-Reactivation Year 1 operations. It contains data covering near-Earth asteroids, Main Belt asteroids, active Main Belt objects, Hildas, Jupiter Trojans, Centaurs, and Jovian and Saturnian irregular satellites. Methodology for physical property determination is described in the referenced articles.

  19. Left Ventricular Diameter and Risk Stratification for Sudden Cardiac Death

    PubMed Central

    Narayanan, Kumar; Reinier, Kyndaron; Teodorescu, Carmen; Uy‐Evanado, Audrey; Aleong, Ryan; Chugh, Harpriya; Nichols, Gregory A.; Gunson, Karen; London, Barry; Jui, Jonathan; Chugh, Sumeet S.

    2014-01-01

    Background Left ventricular (LV) diameter is routinely measured on the echocardiogram but has not been jointly evaluated with the ejection fraction (EF) for risk stratification of sudden cardiac death (SCD). Methods and Results From a large ongoing community‐based study of SCD (The Oregon Sudden Unexpected Death Study; population ≈1 million), SCD cases were compared with geographic controls. LVEF and LV diameter, measured using the LV internal dimension in diastole (categorized as normal, mild, moderate, or severe dilatation using American Society of Echocardiography definitions) were assessed from echocardiograms prior but unrelated to the SCD event. Cases (n=418; 69.5±13.8 years), compared with controls (n=329; 67.7±11.9 years), more commonly had severe LV dysfunction (EF ≤35%; 30.5% versus 18.8%; P<0.01) and larger LV diameter (52.2±10.5 mm versus 49.7±7.9 mm; P<0.01). Moderate or severe LV dilatation (16.3% versus 8.2%; P=0.001) and severe LV dilatation (8.1% versus 2.1%; P<0.001) were significantly more frequent in cases. In multivariable analysis, severe LV dilatation was an independent predictor of SCD (odds ratio 2.5 [95% CI 1.03 to 5.9]; P=0.04). In addition, subjects with both EF ≤35% and severe LV dilatation had higher odds for SCD compared with those with low EF only (odds ratio 3.8 [95% CI 1.5 to 10.2] for both versus 1.7 [95% CI 1.2 to 2.5] for low EF only), suggesting that severe LV dilatation additively increased SCD risk. Conclusion LV diameter may contribute to risk stratification for SCD independent of the LVEF. This readily available echocardiographic measure warrants further prospective evaluation. PMID:25227407

  20. Cost of Czochralski wafers as a function of diameter

    SciTech Connect

    Leipold, M.H.; Radics, C.; Kachare, A.

    1980-02-15

    The impact of diameter in the range of 10 to 15 cm on the cost of wafers sliced from Czochralski ingots is analyzed. Increasing silicon waste and decreasing ingot cost with increasing ingot size are estimated along with projected costs. Results indicate a small but continuous decrease in sheet cost with increasing ingot size in this size range. Sheet costs including silicon are projected to be $50 to $60/m/sup 2/ (1980 $) depending upon technique used.

  1. Measuring angular diameter distances of strong gravitational lenses

    NASA Astrophysics Data System (ADS)

    Jee, I.; Komatsu, E.; Suyu, S. H.

    2015-11-01

    The distance-redshift relation plays a fundamental role in constraining cosmological models. In this paper, we show that measurements of positions and time delays of strongly lensed images of a background galaxy, as well as those of the velocity dispersion and mass profile of a lens galaxy, can be combined to extract the angular diameter distance of the lens galaxy. Physically, as the velocity dispersion and the time delay give a gravitational potential (GM/r) and a mass (GM) of the lens, respectively, dividing them gives a physical size (r) of the lens. Comparing the physical size with the image positions of a lensed galaxy gives the angular diameter distance to the lens. A mismatch between the exact locations at which these measurements are made can be corrected by measuring a local slope of the mass profile. We expand on the original idea put forward by Paraficz and Hjorth, who analyzed singular isothermal lenses, by allowing for an arbitrary slope of a power-law spherical mass density profile, an external convergence, and an anisotropic velocity dispersion. We find that the effect of external convergence cancels out when dividing the time delays and velocity dispersion measurements. We derive a formula for the uncertainty in the angular diameter distance in terms of the uncertainties in the observables. As an application, we use two existing strong lens systems, B1608+656 (zL=0.6304) and RXJ1131-1231 (zL=0.295), to show that the uncertainty in the inferred angular diameter distances is dominated by that in the velocity dispersion, σ2, and its anisotropy. We find that the current data on these systems should yield about 16% uncertainty in DA per object. This improves to 13% when we measure σ2 at the so-called sweet-spot radius. Achieving 7% is possible if we can determine σ2 with 5% precision.

  2. Astronaut Assembly of a 14-Meter-Diameter Microwave Antenna

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Astronaut Jerry Ross is shown assembling a portion of a 14-meter-diameter truss structure in NASAs Neutral Buoyancy Simulator at the Marshall Space Flight Center. The structure is part of a large microwave antenna designed for space-based monitoring of soil moisture levels and ocean temperatures. The underwater assembly tests demonstrated that two astronauts could construct the large antenna in approximately 4-6 hours in space.

  3. Nucleosomal arrays self-assemble into supramolecular globular structures lacking 30-nm fibers.

    PubMed

    Maeshima, Kazuhiro; Rogge, Ryan; Tamura, Sachiko; Joti, Yasumasa; Hikima, Takaaki; Szerlong, Heather; Krause, Christine; Herman, Jake; Seidel, Erik; DeLuca, Jennifer; Ishikawa, Tetsuya; Hansen, Jeffrey C

    2016-05-17

    The existence of a 30-nm fiber as a basic folding unit for DNA packaging has remained a topic of active discussion. Here, we characterize the supramolecular structures formed by reversible Mg(2+)-dependent self-association of linear 12-mer nucleosomal arrays using microscopy and physicochemical approaches. These reconstituted chromatin structures, which we call "oligomers", are globular throughout all stages of cooperative assembly and range in size from ~50 nm to a maximum diameter of ~1,000 nm. The nucleosomal arrays were packaged within the oligomers as interdigitated 10-nm fibers, rather than folded 30-nm structures. Linker DNA was freely accessible to micrococcal nuclease, although the oligomers remained partially intact after linker DNA digestion. The organization of chromosomal fibers in human nuclei in situ was stabilized by 1 mM MgCl2, but became disrupted in the absence of MgCl2, conditions that also dissociated the oligomers in vitro These results indicate that a 10-nm array of nucleosomes has the intrinsic ability to self-assemble into large chromatin globules stabilized by nucleosome-nucleosome interactions, and suggest that the oligomers are a good in vitro model for investigating the structure and organization of interphase chromosomes. PMID:27072995

  4. From Agglomerates of Spheres to Irregularly Shaped Particles: Determination of Dynamic Shape Factors from Measurements of Mobility and Vacuum Aerodynamic Diameters

    SciTech Connect

    Zelenyuk, Alla; Cai, Yong; Imre, Dan G.

    2006-03-01

    With the advert of aerosol instrumentation it has become possible to simultaneously measure individual particle mobility and vacuum aerodynamic diameters. For spherical particles these two diameters yield individual particle density. In contrast, assigning a physical meaning to the mobility or aerodynamic diameter of aspherical particles is not straightforward. This paper presents an experimental exploration of the effect of particle shape on the relationship between mobility and vacuum aerodynamic diameters. We make measurements on systems of three types: 1) Agglomerates of spheres, for which the density and the volume are known; 2) Ammonium sulfate, sodium chloride, succinic acid and lauric acid irregularly shaped particles of known density; and 3) Internally mixed particles, containing organics and ammonium sulfate, of unknown density and shape. For agglomerates of spheres we observed alignment effects in the DMA and report the first measurements of the dynamic shape factors (DSFs) in free molecular regime. We present here the first experimental determination of the DSF of ammonium sulfate particles. We find for ammonium sulfate particles a DSF that increases from 1.03 to 1.07 as particle mobility diameter increases from 160 nm to 500 nm. Three types of NaC1 particles were generated and characterized: nearly spherical particles with DSF of ~1.02; cubic with DSF that increases from 1.065 to 1.17 as particle mobility diameter increases from 200 nm to 900 nm; and compact agglomerates with DSF 1.3-1.4. Organic particles were found very nearly spherical. The data suggest that particles composed of binary mixtures of ammonium sulfate and succinic acid have lower dynamic shape factors than pure ammonium sulfate particles. However, for internally mixed ammonium sulfate and lauric acid particles we cannot distinguish between nearly spherical particles with low density and particles with DSF of 1.17.

  5. AIMS mask qualification for 32nm node

    NASA Astrophysics Data System (ADS)

    Richter, Rigo; Thaler, Thomas; Seitz, Holger; Stroessner, Ulrich; Scheruebl, Thomas

    2009-10-01

    Moving forward to 32nm node and below optical lithography using 193nm is faced with complex requirements to be solved. Mask makers are forced to address both Double Patterning Techniques and Computational Lithography approaches such as Source Mask Optimizations and Inverse Lithography. Additionally, lithography at low k1 values increases the challenges for mask repair as well as for repair verification and review by AIMSTM. Higher CD repeatability, more flexibility in the illumination settings as well as significantly improved image performance must be added when developing the next generation mask qualification equipment. This paper reports latest measurement results verifying the appropriateness of the latest member of AIMSTM measurement tools - the AIMSTM 32-193i. We analyze CD repeatability measurements on lines and spaces pattern. The influence of the improved optical performance and newly introduced interferometer stage will be verified. This paper highlights both the new Double Patterning functionality emulating double patterning processes and the influence of its critical parameters such as overlay errors and resist impact. Beneficial advanced illumination schemes emulating scanner illumination document the AIMSTM 32-193i to meet mask maker community's requirements for the 32nm node.

  6. Time-delay cosmography: increased leverage with angular diameter distances

    NASA Astrophysics Data System (ADS)

    Jee, I.; Komatsu, E.; Suyu, S. H.; Huterer, D.

    2016-04-01

    Strong lensing time-delay systems constrain cosmological parameters via the so-called time-delay distance and the angular diameter distance to the lens. In previous studies, only the former information was used in forecasting cosmographic constraints. In this paper, we show that the cosmological constraints improve significantly when the latter information is also included. Specifically, the angular diameter distance plays a crucial role in breaking the degeneracy between the curvature of the Universe and the time-varying equation of state of dark energy. Using a mock sample of 55 bright quadruple lens systems based on expectations for ongoing/future imaging surveys, we find that adding the angular diameter distance information to the time-delay distance information and the Planck's measurements of the cosmic microwave background anisotropies improves the constraint on the constant equation of state by 30%, on the time variation in the equation of state by a factor of two, and on the Hubble constant in the flat ΛCDM model by a factor of two. Therefore, previous forecasts for the statistical power of time-delay systems were overly pessimistic, i.e., time-delay systems are more powerful than previously appreciated.

  7. J-integral of circumferential crack in large diameter pipes

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Chao, Yuh J.; Sutton, M. A.; Lam, P. S.; Mertz, G. E.

    Large diameter thin-walled pipes are encountered in a low pressure nuclear power piping system. Fracture parameters such as K and J, associated with postulated cracks, are needed to assess the safety of the structure, for example, prediction of the onset of tile crack growth and the stability of the crack. The Electric Power Research Institute (EPRI) has completed a comprehensive study of cracks in pipes and handbook-type data is available. However, for some large diameter, thin-walled pipes the needed information is not included in the handbook. This paper reports our study of circumferential cracks in large diameter, thin-walled pipes (R/t=30 to 40) under remote bending or tension loads. Elastic-Plastic analyses using the finite element method were performed to determine the elastic and fully plastic J values for various pipe/crack geometries. A non-linear Ramberg-Osgood material model is used with strain hardening exponents (n) that range from 3 to 10. A number of circumferential, through thickness cracks were studied with half crack angles ranging from 0.063(pi) to 0.5(pi). Results are tabulated for use with the EPRI estimation scheme.

  8. Mechanical analysis of conventional and small diameter conical implant abutments

    PubMed Central

    Moris, Izabela Cristina Maurício; Faria, Adriana Cláudia Lapria; de Mattos, Maria da Gloria Chiarello; Ribeiro, Ricardo Faria

    2012-01-01

    PURPOSE The aim of the present study was to evaluate if a smaller morse taper abutment has a negative effect on the fracture resistance of implant-abutment connections under oblique compressive loads compared to a conventional abutment. MATERIALS AND METHODS Twenty morse taper conventional abutments (4.8 mm diameter) and smaller abutments (3.8 mm diameter) were tightened (20 Ncm) to their respective implants (3.5 × 11 mm) and after a 10 minute interval, implant/abutment assemblies were subjected to static compressive test, performed in a universal test machine with 1 mm/min displacement, at 45° inclination. The maximum deformation force was determined. Data were statistically analyzed by student t test. RESULTS Maximum deformation force of 4.8 mm and 3.8 mm abutments was approximately 95.33 kgf and 95.25 kgf, respectively, but no fractures were noted after mechanical test. Statistical analysis demonstrated that the evaluated abutments were statistically similar (P=.230). CONCLUSION Abutment measuring 3.8 mm in diameter (reduced) presented mechanical properties similar to 4.8 mm (conventional) abutments, enabling its clinical use as indicated. PMID:22977724

  9. The method for detecting diffusion ring diameter in Hemagglutinin measuring

    NASA Astrophysics Data System (ADS)

    Jing, Wenbo; Liu, Xue; Duan, Jin; Wang, Xiao-man

    2014-11-01

    The diffuser ring diameter measurement is the most critical in hemagglutinin Measuring. The traditional methods, such as a vernier caliper or high-definition scanned images are subjective and low for the measurement data reliability. Propose high-resolution diffusion ring image for drop-resolution processing, adaptive Canny operator and local detection method to extract complete and clear diffusion ring boundaries, and finally make use of polynomial interpolation algorithm to make diffusion ring outer boundary pixel coordinates achieve sub-pixel accuracy and the least-squares fitting circle algorithm to calculate the precise center of the circle and the diameter of the diffuser ring. Experimental results show that the method detection time is only 63.61ms, which is a faster speed; diffuser ring diameter estimation error can achieve 0.55 pixel, high stability in experimental data. This method is adapted to the various types of influenza vaccine hemagglutinin content measurements, and has important value in the influenza vaccine quality detection.

  10. Tree height-diameter allometry across the United States.

    PubMed

    Hulshof, Catherine M; Swenson, Nathan G; Weiser, Michael D

    2015-03-01

    The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height-diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales. PMID:25859325

  11. Tree height–diameter allometry across the United States

    PubMed Central

    Hulshof, Catherine M; Swenson, Nathan G; Weiser, Michael D

    2015-01-01

    The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height–diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales. PMID:25859325

  12. Subwavelength-diameter silica wires for microscale optical components

    NASA Astrophysics Data System (ADS)

    Tong, Limin; Mazur, Eric

    2005-04-01

    Subwavelength-diameter silica wires fabricated using a taper-drawing approach exhibit excellent diameter uniformity and atomic-level smoothness, making them suitable for low-loss optical wave guiding from the UV to the near-infrared. Such air-clad silica wires can be used as single-mode waveguides; depending on wavelength and wire diameter, they either tightly confine the optical fields or leave a certain amount of guided energy outside the wire in the form of evanescent waves. Using these wire waveguides as building blocks we assembled microscale optical components such as linear waveguides, waveguide bends and branch couplers on a low-index, non-dissipative silica aerogel substrate. These components are much smaller than comparable existing devices and have low optical loss, indicating that the wire-assembly technique presented here has great potential for developing microphotonics devices for future applications in a variety of fields such as optical communication, optical sensing and high-density optical integration.

  13. Needle-free transdermal delivery using PLGA nanoparticles: effect of particle size, injection pressure and syringe orifice diameter.

    PubMed

    Park, Chan Hee; Tijing, Leonard D; Kim, Cheol Sang; Lee, Kang-Min

    2014-11-01

    The aim of this study is to investigate the effects of particle size and other injection factors on the skin penetration of nanoparticles delivered with a needle-free injector. Experimental and simulation tests were carried out at various parameters. In addition to testing different sizes of nanoparticles, we also observed the effects of several injection pressures and syringe orifice diameters (SOD) on the dispersion pattern of the nanoparticles after injection. Our results showed that as the nanoparticle size increased from 45 nm to 452 nm, the resulting puncture opening, channel diameter, and depth of the nanoparticle dispersion decreased, but the width of the dispersion increased. Conversely, as the SOD increased, the puncture opening, channel diameter, and depth of the dispersion increased, but width of the dispersion decreased. Increasing the injection pressure also decreased the size, depth, and width of the puncture opening. These results identify how these three parameters affect nanoparticle delivery from a needle-free injector; therefore, our findings will be beneficial for optimization and further study of needle-free injectors as a mechanism for transdermal delivery of nanoparticles. PMID:25456991

  14. Electrical characteristics of field-effect transistors based on indium arsenide nanowire thinner than 10 nm

    SciTech Connect

    Fu, Mengqi; Yang, Yingjun; Shi, Tuanwei; Zhang, Zhiyong; Xu, H. Q.; Chen, Qing; Pan, Dong; Zhao, Jianhua

    2014-10-06

    To suppress short channel effects, lower off-state leakage current and enhance gate coupling efficiency, InAs nanowires (NWs) with diameter smaller than 10 nm could be needed in field-effect transistors (FETs) as the channel length scales down to tens of nanometers to improve the performance and increase the integration. Here, we fabricate and study FETs based on ultrathin wurtzite-structured InAs NWs, with the smallest NW diameter being 7.2 nm. The FETs based on ultrathin NWs exhibit high I{sub on}/I{sub off} ratios of up to 2 × 10{sup 8}, small subthreshold swings of down to 120 mV/decade, and operate in enhancement-mode. The performance of the devices changes as a function of the diameter of the InAs NWs. The advantages and challenges of the FETs based on ultrathin NWs are discussed.

  15. Sub-50nm extreme ultraviolet holographic imaging

    NASA Astrophysics Data System (ADS)

    Wachulak, P. W.; Marconi, M. C.; Bartels, R. A.; Menoni, C. S.; Rocca, J. J.

    2009-05-01

    Imaging tools for nanoscicence involving sub-100-nm scale objects have been dominated by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and electron microscopy (SEM, TEM). These imaging techniques have contributed substantially to the development of nanoscience, providing a very powerful diagnostic tool capable of obtaining images with atomic resolution or as a subsidiary mechanism to arrange or modify surfaces also at the atomic scale [1,2]. However, some important problems have persisted traditional nanoscale imaging techniques. For example when scanning a nanometer size object that is not attached rigidly to a surface the interaction with the tip significantly perturbs the specimen degrading or eventually precluding the image acquisition. Electron microscopy often requires surface preparation, consisting of metallization of the sample to avoid surface charging. Additionally the metallization of the sample may alter its characteristics and also limits the resolution. In both cases, if the sample is large (millimeters in size) due to the limited field of view, the image obtained with these conventional methods is only representative of a very small portion of the object. Wavelength-limited holographic imaging using carbon nanotubes as the test object with a table-top extreme ultraviolet (EUV) laser operating at 46.9 nm will be discussed. The resolution achieved in this imaging is evaluated with a rigorous correlation image analysis and confirmed with the conventional knife-edge test. The nano-holography presented requires no optics or critical beam alignment; thus the hologram recording scheme is very simple and does not need special sample preparation. In holography, image contrast requires absorption to provide scattering by the illuminating beam. The EUV laser wavelength employed in this experiment (46.9nm) is advantageous because carbon based materials typically exhibit very small attenuation lengths, around 25 nm. The high absorption of

  16. A Sounding Rocket Mission Concept to Acquire High-Resolution Radiometric Spectra Spanning the 9 nm - 31 nm Wavelength Range

    NASA Technical Reports Server (NTRS)

    Krause, L. Habash; Cirtain, Jonathan; McGuirck, Michael; Pavelitz, Steven; Weber, Ed.; Winebarger, Amy

    2012-01-01

    When studying Solar Extreme Ultraviolet (EUV) emissions, both single-wavelength, two- dimensional (2D) spectroheliograms and multi-wavelength, one-dimensional (1D) line spectra are important, especially for a thorough understanding of the complex processes in the solar magnetized plasma from the base of the chromosphere through the corona. 2D image data are required for a detailed study of spatial structures, whereas radiometric (i.e., spectral) data provide information on relevant atomic excitation/ionization state densities (and thus temperature). Using both imaging and radiometric techniques, several satellite missions presently study solar dynamics in the EUV, including the Solar Dynamics Observatory (SDO), Hinode, and the Solar-Terrestrial Relations Observatory (STEREO). The EUV wavelengths of interest typically span 9 nm to 31 nm, with the shorter wavelengths being associated with the hottest features (e.g., intense flares and bright points) and the longer wavelengths associated with cooler features (e.g., coronal holes and filaments). Because the optical components of satellite instruments degrade over time, it is not uncommon to conduct sounding rocket underflights for calibration purposes. The authors have designed a radiometric sounding rocket payload that could serve as both a calibration underflight for and a complementary scientific mission to the upcoming Solar Ultraviolet Imager (SUVI) mission aboard the GOES-R satellite (scheduled for a 2015 launch). The challenge to provide quality radiometric line spectra over the 9-31 nm range covered by SUVI was driven by the multilayer coatings required to make the optical components, including mirrors and gratings, reflective over the entire range. Typically, these multilayers provide useful EUV reflectances over bandwidths of a few nm. Our solution to this problem was to employ a three-telescope system in which the optical components were coated with multilayers that spanned three wavelength ranges to cover

  17. Size controlled synthesis of sub-100 nm monodisperse poly(methylmethacrylate) nanoparticles using surfactant-free emulsion polymerization.

    PubMed

    Camli, Sevket Tolga; Buyukserin, Fatih; Balci, Oguz; Budak, Gurer Guven

    2010-04-15

    Surfactant-free emulsion polymerization (SFEP) is a well-known technique for the production of polymeric nanoparticles that does not require post-synthetic cleaning steps. Obtaining hydrophobic particles at sub-100 nm scale, however, is quite challenging with this polymerization method. Here, we demonstrate a single step synthetic approach that yields poly(methylmethacrylate) (PMMA) nanoparticles with controlled sub-100 nm size and relatively high resultant solid content. Dynamic light scattering (DLS) was used for the particle characterization. Spherical and uniformly sized nanoparticles were confirmed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Acetone was used as a cosolvent in order to obtain monodisperse sub-100 nm diameter particles. Stable PMMA nanoparticle dispersions were obtained for all formulations where the persulfate initiator causes the negative charges on the particle surface. The effects of acetone, monomer and initiator concentration were studied to optimize average particle hydrodynamic diameter and polydispersity index of the final particles. Non-crosslinked monodisperse PMMA nanoparticles (polydispersity index less than 0.05) with diameters from 32 nm to 72 nm were synthesized by using this method. PMID:20138293

  18. Evidence of gating in hundred nanometer diameter pores: an experimental and theoretical study

    SciTech Connect

    Letant, S E; Schaldach, C M; Johnson, M R; Sawvel, A; Bourcier, W L; Wilson, W D

    2006-01-11

    We report on the observation of an unexpected gating mechanism at the 100 nm scale on track-etched polycarbonate membranes. Transport measurements of methyl viologen performed by absorption spectroscopy under various pH conditions demonstrated that perfect gating was achieved for 100 nm diameter pores at pH 2, while the positively charged molecular ions moved through the membrane according to diffusion laws at pH 5. An oppositely charged molecular ion, naphthalene disulfonate, in the same membrane, showed the opposite trend: diffusion of the negative ion at pH 2 and perfect gating at pH 5. The influence of parameters such as ionic strength and membrane surface coating were also investigated. A theoretical study of the system shows that at this larger length scale the magnitude of the electric field in the vicinity of the pores is too small to account for the experimental observations, rather, it is the surface trapping of the mobile ion (Cl{sup -} or Na{sup +}) which gives rise to the gating phenomena. This surprising effect might have potential applications for high-throughput separation of large molecules and bio-organisms.

  19. Synthesis of long indium nitride nanowires with uniform diameters in large quantities.

    PubMed

    Luo, Shudong; Zhou, Weiya; Zhang, Zengxing; Liu, Lifeng; Dou, Xinyuan; Wang, Jianxiong; Zhao, Xiaowei; Liu, Dongfang; Gao, Yan; Song, Li; Xiang, Yanjuan; Zhou, Jianjun; Xie, Sishen

    2005-10-01

    Large quantities of indium nitride (InN) nanowires are synthesized by the in situ nitriding of indium oxide (In(2)O(3)) powders in an ammonia (NH(3)) flux. Tens of milligrams of nanowires are obtained in one batch. Every 100 mg of In(2)O(3) starting powder can produce up to 65 mg of InN nanowires under the optimized conditions. The synthesized nanowires grow along the [001] direction with excellent crystallinity. They are of high purity and are 30-50 microm in length with an almost uniform diameter of about 100 nm. Photoluminescence measurements of the nanowires exhibit a strong peak at 707 nm. An optical bandgap of about 1.7 eV is estimated based on the absorption spectrum. The experimental results also demonstrate that the approach of nitriding In(2)O(3) powders in situ is feasible for the synthesis of high-purity InN nanowires in large quantities, with good reproducibility and without catalyst materials. The synthesis of InN nanowires in large quantities would be of benefit to the further study and understanding of their intrinsic properties, as well as being advantageous for their potential application in nanodevices. PMID:17193386

  20. Domain wall motion in sub-100 nm magnetic wire

    NASA Astrophysics Data System (ADS)

    Siddiqui, Saima; Dutta, Sumit; Currivan, Jean Anne; Ross, Caroline; Baldo, Marc

    2015-03-01

    Nonvolatile memory devices such as racetrack memory rely on the manipulation of domain wall (DW) in magnetic nanowires, and scaling of these devices requires an understanding of domain wall behavior as a function of the wire width. Due to the increased importance of edge roughness and magnetostatic interaction, DW pinning increases dramatically as the wire dimensions decrease and stochastic behavior is expected depending on the distribution of pinning sites. We report on the field driven DW statistics in sub-100 nm wide nanowires made from Co films with very small edge roughness. The nanowires were patterned in the form of a set of concentric rings of 10 μm diameter. Two different width nanowires with two different spacings have been studied. The rings were first saturated in plane to produce onion states and then the DWs were translated in the wires using an orthogonal in-plane field. The position of the DWs in the nanowires was determined with magnetic force microscopy. From the positions of the DWs in the nanowires, the strength of the extrinsic pinning sites was identified and they follow two different distributions in two different types of nanowire rings. For the closely spaced wires, magnetostatic interactions led to correlated movement of DWs in neighboring wires. The implications of DW pinning and interaction in nanoscale DW devices will be discussed.

  1. Ion exclusion by sub-2-nm carbon nanotube pores

    PubMed Central

    Fornasiero, Francesco; Park, Hyung Gyu; Holt, Jason K.; Stadermann, Michael; Grigoropoulos, Costas P.; Noy, Aleksandr; Bakajin, Olgica

    2008-01-01

    Biological pores regulate the cellular traffic of a large variety of solutes, often with high selectivity and fast flow rates. These pores share several common structural features: the inner surface of the pore is frequently lined with hydrophobic residues, and the selectivity filter regions often contain charged functional groups. Hydrophobic, narrow-diameter carbon nanotubes can provide a simplified model of membrane channels by reproducing these critical features in a simpler and more robust platform. Previous studies demonstrated that carbon nanotube pores can support a water flux comparable to natural aquaporin channels. Here, we investigate ion transport through these pores using a sub-2-nm, aligned carbon nanotube membrane nanofluidic platform. To mimic the charged groups at the selectivity region, we introduce negatively charged groups at the opening of the carbon nanotubes by plasma treatment. Pressure-driven filtration experiments, coupled with capillary electrophoresis analysis of the permeate and feed, are used to quantify ion exclusion in these membranes as a function of solution ionic strength, pH, and ion valence. We show that carbon nanotube membranes exhibit significant ion exclusion that can be as high as 98% under certain conditions. Our results strongly support a Donnan-type rejection mechanism, dominated by electrostatic interactions between fixed membrane charges and mobile ions, whereas steric and hydrodynamic effects appear to be less important. PMID:18539773

  2. Estimating the Average Diameter of a Population of Spheres from Observed Diameters of Random Two-Dimensional Sections

    NASA Technical Reports Server (NTRS)

    Kong, Maiying; Bhattacharya, Rabi N.; James, Christina; Basu, Abhijit

    2003-01-01

    Size distributions of chondrules, volcanic fire-fountain or impact glass spherules, or of immiscible globules in silicate melts (e.g., in basaltic mesostasis, agglutinitic glass, impact melt sheets) are imperfectly known because the spherical objects are usually so strongly embedded in the bulk samples that they are nearly impossible to separate. Hence, measurements are confined to two-dimensional sections, e.g. polished thin sections that are commonly examined under reflected light optical or backscattered electron microscopy. Three kinds of approaches exist in the geologic literature for estimating the mean real diameter of a population of 3D spheres from 2D observations: (1) a stereological approach with complicated calculations; (2) an empirical approach in which independent 3D size measurements of a population of spheres separated from their parent sample and their 2D cross sectional diameters in thin sections have produced an array of somewhat contested conversion equations; and (3) measuring pairs of 2D diameters of upper and lower surfaces of cross sections each sphere in thin sections using transmitted light microscopy. We describe an entirely probabilistic approach and propose a simple factor of 4/x (approximately equal to 1.27) to convert the 2D mean size to 3D mean size.

  3. Scaling of laser-induced contamination growth at 266nm and 355nm

    NASA Astrophysics Data System (ADS)

    Ließmann, M.; Jensen, L.; Balasa, I.; Hunnekuhl, M.; Büttner, A.; Weßels, P.; Neumann, J.; Ristau, D.

    2015-11-01

    The growth of laser-induced contamination (LIC) on optical components in extraterrestrial missions is a known issue especially for the UV spectral region. The Laser Zentrum Hannover e.V. is responsible for the development of a pulsed laser-system operating at a wavelength of 266 nm for the ExoMars mission and for the qualification of used optics and materials regarding LIC. In this context, toluene was utilized which is an often used model contaminant in LIC studies. Test cycles based on the application of the two UV wavelengths 355 nm and 266 nm on fused silica substrates and ARcoated optics are conducted and the observed contamination effects are compared. This scaling allows for a rough estimate of the destructive influence of LIC on space optics degradation at 266 nm. Further tests will be performed with materials integrated into the ExoMars-laser-head under near-operation environmental conditions.

  4. An 885-nm Direct Pumped Nd:CNGG 1061 nm Q-Switched Laser

    NASA Astrophysics Data System (ADS)

    Li, Qi-Nan; Zhang, Tao; Feng, Bao-Hua; Zhang, Zhi-Guo; Zhang, Huai-Jin; Wang, Ji-Yang

    2014-07-01

    The 885 nm direct pumping method, directly into the 4F3/2 emitting level of Nd3+ ion, is used to a Nd:CNGG crystal to product passive Q-switched 1061 nm laser pulses, for the first time to the best of our knowledge. A maximum average output power of 1.16 W for 1061 nm Q-switched pulses and a repetition rate of 12.54 kHz are obtained. The pulse width is measured to be 24 ns and the peak power is 3.843 kW. A high-quality fundamental transverse mode can be observed owing to the reduction of the thermal effect for Nd:CNGG crystal by 885 nm direct pumping.

  5. 1064 nm Nd:YAG laser intracavity pumped at 946 nm and sum-frequency mixing for an emission at 501 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Jin, G. Y.; Wang, J. G.; Yin, X. D.; Zhang, A. F.

    2010-05-01

    We present for the first time a Nd:YAG laser emitting at 1064 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1064 nm intracavity pumped at 946 nm. Intracavity sum-frequency mixing at 946 and 1064 nm was then realized in a LBO crystal to reach the cyan range. We obtained a continuous-wave output power of 485 mW at 501 nm with a pump laser diode emitting 25.4 W at 809 nm.

  6. Utilising a loop structure to allow a microfiber coupler with larger taper diameters to be used for sensing

    NASA Astrophysics Data System (ADS)

    Wei, Fangfang; Farrell, Gerald; Wu, Qiang; Semenova, Yuliya

    2016-05-01

    This paper examines a technique that utilizes a Sagnac loop with a microfiber coupler (MFC) as a coupler which allows the MFC to operate effectively as a sensor but with larger than normal tapered fiber diameters. The proposed structure is found to be suitable for temperature and refractive index (RI) sensing. It is shown that a variation in the surrounding of the MFC RI results in a shift of the output spectrum, while a temperature variation leads to changes in the intensity of the interference dips. A decrease in the waist diameter of the MFC results in an increase in the sensitivity to temperature. For MFC structures based on a 5.6 μm and a 3 μm fiber waist diameter, the minimum transmission power level of a selected spectral dip decreases by 1.7 dB and 5.03 dB respectively, as the temperature changes from 18 °C to 44 °C. A change in the surrounding RI from 1.334 to 1.395 results in the spectral redshift of 8 nm using a 5.6 μm fiber waist diameter. By functionalizing the surface of the MFC with various materials, the structure could potentially be used for sensing of other parameters.

  7. Deep ultraviolet (254 nm) focal plane array

    NASA Astrophysics Data System (ADS)

    Cicek, Erdem; Vashaei, Zahra; McClintock, Ryan; Razeghi, Manijeh

    2011-10-01

    We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A/cm2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

  8. Fluorinated dissolution inhibitors for 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Hamad, Alyssandrea H.; Bae, Young C.; Liu, Xiang-Qian; Ober, Christopher K.; Houlihan, Francis M.; Dabbagh, Gary; Novembre, Anthony E.

    2002-07-01

    Fluorinated dissolution inhibitors (DIs) for 157 nm lithography were designed and synthesized as part of an ongoing study on the structure/property relationships of photoresist additives. The problem of volatilization of small DI candidates was observed from matrices such as poly(methyl methacrylate) (PMMA) and poly(hexafluorohydroxy-isopropyl styrene) (PHFHIPS) during post-apply bake cycles using Fourier Transform Infrared Spectroscopy (FT-IR). To avoid this problem, low volatility fluorinated inhibitors were designed and synthesized. Three fluorinated DIs, perfluorosuberic acid bis-(2,2,2,-trifluoro-1-phenyl-1-trifluoromethyl-ethyl) ester (PFSE1), perfluorosuberic acid bis-[1-(4-trifluoromethyl-phenyl)-ethyl] ester (PFSE2) and a fluorinated phenylmethanediol diester (FPMD1), largely remained in a PHFHIPS film during the post-apply bake. The dissolution behavior of the two fluorinated diesters was studied and found to slow down the dissolution rate of PHFHIPS with inhibition factors of 1.9 and 1.6, respectively. The absorbance of PHFHIPS films containing 10 wt% of the diester inhibitors is 3.6 AU/micron compared with an absorbance of 3.3 AU/micron for the polymer itself. The absorbance of 10% FPMD1 in PHFHIPS was measured as 3.5 AU/micron compared with an absorbance of 3.4 AU/micron for the polymer itself. Thus, the non-volatility and transparency of the fluorinated inhibitors at 157 nm as well as their ability to reduce the development rate of fluorinated polymers make them suitable for use in a 157 nm resist system.

  9. Quantitative comparison of the OCT imaging depth at 1300 nm and 1600 nm

    PubMed Central

    Kodach, V. M.; Kalkman, J.; Faber, D. J.; van Leeuwen, T. G.

    2010-01-01

    One of the present challenges in optical coherence tomography (OCT) is the visualization of deeper structural morphology in biological tissues. Owing to a reduced scattering, a larger imaging depth can be achieved by using longer wavelengths. In this work, we analyze the OCT imaging depth at wavelengths around 1300 nm and 1600 nm by comparing the scattering coefficient and OCT imaging depth for a range of Intralipid concentrations at constant water content. We observe an enhanced OCT imaging depth for 1600 nm compared to 1300 nm for Intralipid concentrations larger than 4 vol.%. For higher Intralipid concentrations, the imaging depth enhancement reaches 30%. The ratio of scattering coefficients at the two wavelengths is constant over a large range of scattering coefficients and corresponds to a scattering power of 2.8 ± 0.1. Based on our results we expect for biological tissues an increase of the OCT imaging depth at 1600 nm compared to 1300 nm for samples with high scattering power and low water content. PMID:21258456

  10. Modification of laminar flow ultrafine condensation particle counters for the enhanced detection of 1 nm condensation nuclei

    SciTech Connect

    Kuang, C.; Chen, M.; McMurry, P. H.; Wang, J.

    2011-10-01

    This paper describes simple modifications to thermally diffusive laminar flow ultrafine condensation particle counters (UCPCs) that allow detection of {approx}1 nm condensation nuclei with much higher efficiencies than have been previously reported. These nondestructive modifications were applied to a commercial butanol based UCPC (TSI 3025A) and to a diethylene glycol-based UCPC (UMN DEG-UCPC). Size and charge dependent detection efficiencies using the modified UCPCs (BNL 3025A and BNL DEGUCPC) were measured with high resolution mobility classified aerosols composed of NaCl, W, molecular ion standards of tetraalkyl ammonium bromide, and neutralizer-generated ions. With negatively charged NaCl aerosol, the BNL 3025A and BNL DEGUCPC achieved detection efficiencies of 37% (90x increase over TSI 3025A) at 1.68 nm mobility diameter (1.39 nm geometric diameter) and 23% (8x increase over UMN DEG-UCPC) at 1.19 nm mobility diameter (0.89 nm geometric diameter), respectively. Operating conditions for both UCPCs were identified that allowed negatively charged NaCl and W particles, but not negative ions of exactly the same mobility size, to be efficiently detected. This serendipitous material dependence, which is not fundamentally understood, suggests that vapor condensation might sometimes allow for the discrimination between air 'ions' and charged 'particles.' As a detector in a scanning mobility particle spectrometer (SMPS), a UCPC with this strong material dependence would allow for more accurate measurements of sub-2 nm aerosol size distributions due to the reduced interference from neutralizer-generated ions and atmospheric ions, and provide increased sensitivity for the determination of nucleation rates and initial particle growth rates.

  11. Photolysis of formic acid at 355 nm

    NASA Astrophysics Data System (ADS)

    Martinez, Denhi; Bautista, Teonanacatl; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2015-05-01

    Formic acid is well known as a food additive and recently an application on fuel cell technology has emerged. In this work we have studied the dissociative ionization process by multiphoton absorption of formic acid molecules at 355nm wavelength photons, using TOF spectrometry in reflectron mode (R-TOF). Some of the most abundant ionic fragments produced are studied at different settings of the laser harmonic generator. The dependence of the products on these conditions is reported. This work was supported by CONACYT Project 165410 and PAPIIT IN102613 and IN101215.

  12. 248nm silicon photoablation: Microstructuring basics

    NASA Astrophysics Data System (ADS)

    Poopalan, P.; Najamudin, S. H.; Wahab, Y.; Mazalan, M.

    2015-05-01

    248nm pulses from a KrF excimer laser was used to ablate a Si wafer in order to ascertain the laser pulse and energy effects for use as a microstructuring tool for MEMS fabrication. The laser pulses were varied between two different energy levels of 8mJ and 4mJ while the number of pulses for ablation was varied. The corresponding ablated depths were found to range between 11 µm and 49 µm, depending on the demagnified beam fluence.

  13. 248nm silicon photoablation: Microstructuring basics

    SciTech Connect

    Poopalan, P.; Najamudin, S. H.; Wahab, Y.; Mazalan, M.

    2015-05-15

    248nm pulses from a KrF excimer laser was used to ablate a Si wafer in order to ascertain the laser pulse and energy effects for use as a microstructuring tool for MEMS fabrication. The laser pulses were varied between two different energy levels of 8mJ and 4mJ while the number of pulses for ablation was varied. The corresponding ablated depths were found to range between 11 µm and 49 µm, depending on the demagnified beam fluence.

  14. Characterization of Large Diameter PMTs for Kaon Cerenkov Detector

    NASA Astrophysics Data System (ADS)

    Boylan, Derek

    2014-09-01

    The 12 GeV upgrade at the Jefferson Laboratory allows for unique new opportunities to study hadron structure through kaon production in Hall C, a threshold aerogel detector was constructed at the Catholic University of America. It uses the emission of Cerenkov radiation at different indices of refraction ranging from 1.03 to 1.01 to distinguish pions, kaons, and protons. An important aspect of this detector is the collection of very small amounts of light, in particular as the aerogel refractive index decreases. The Hall C aerogel detector uses the Photonis XP4500 large-diameter photomultiplier tubes (PMT) in order to detect these small traces of light. The purpose of this project is to explore the performance of alternative large-diameter PMTs and compares them to that of the XP4500. The PMT uniformity across the photocathode was characterized through scans along the surface of the PMT with a low-intensity, focused LED, thereby creating a 3D image of the gain at each section. The method of scanning consists of a two axis step motor moving an LED light source on a 100 x 100 grid parallel to the face of the PMT, with 30 pulses of light from the LED at each step. The step motor scans with a resolution of 1.2 mm. Scans conducted in this manner result in high resolution images which pick up most sensitive/non-sensitive spots on the photocathode. In this presentation I will present the results of the characterization and performance test of the XP4500 and comparison to alternative large-diameter PMT models. The 12 GeV upgrade at the Jefferson Laboratory allows for unique new opportunities to study hadron structure through kaon production in Hall C, a threshold aerogel detector was constructed at the Catholic University of America. It uses the emission of Cerenkov radiation at different indices of refraction ranging from 1.03 to 1.01 to distinguish pions, kaons, and protons. An important aspect of this detector is the collection of very small amounts of light, in

  15. The action of NIR (808nm) laser radiation and gold nanorods labeled with IgA and IgG human antibodies on methicillin-resistant and methicillin sensitive strains of Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Petrov, Pavel O.; Ratto, Fulvio; Centi, Sonia; Pini, Roberto; Tuchin, Valery V.

    2015-03-01

    The effect of NIR laser radiation (808 nm) on methicillin-sensitive and methicillin resistant strains of Staphylococcus aureus incubated with gold nanorods is studied. Nanorods having length of 44 (± 4) nm and diameter of 10 (± 3) nm with the absorption maximum in the NIR (800 nm), functionalized with human immunoglobulins IgA and IgG, were synthesized and used in the studies. The killing ability up to 97% of the microorganism populations by using this nanotechnology was shown.

  16. Achieving Diameter-Selective Separation of Single-Walled Carbon Nanobutes by Using Polymer Conformation-Confined Helical Cavity.

    SciTech Connect

    Chen, Yusheng; Xu, Yongqian; Perry, Kelly A; Sokolov, Alexei P; More, Karren Leslie; Pang, Yi

    2012-01-01

    A water-soluble poly[(m-phenylenevinylene)-alt-(p-phenylenevinylene)] (PmPV) 2 has been synthesized, which exhibits an unsymmetrical substitution pattern on the para-phenylene unit. With one substituent being hydrophilic while the other being hydrophobic, the polymer chain has a higher tendency to fold in aqueous solution, thereby promoting the helical conformation. The polymer is found to selectively disperse the SWNTs of small diameters (d=0.75-0.84 nm), in sharp contrast to PmPV 1 with a symmetrical substitution pattern. The intriguing diameter-based selectivity is believed to be associated with the confined helical conformation, which provides a suitable cavity to host the SWNT of proper sizes. The study thus provides a useful demonstration that the polymer conformation can have a profound impact on the SWNT sorting.

  17. Europa's Surface Properties from Secondary Crater Depth/Diameter Ratios

    NASA Astrophysics Data System (ADS)

    Bierhaus, Edward B.; Chapman, C. R.; Schenk, P. M.

    2007-10-01

    We find that secondary craters on Europa tend towards smaller depth-to-diameter (d/D) ratios than primary craters, consistent with observations on other cratered surfaces (the Moon and Mars). We measure craters near the resolution limit, so an individual crater profile is noisy and not definitive; however, the aggregate statistics of over 100 profiles demonstrate a systematic trend for shallow profiles. Primary crater collapse from a simple bowl shape to a more shallow profile (or more complex morphology) is a function of material strength and surface gravity: the transition will happen at smaller diameters for weaker surfaces or for those with higher surface gravity. However, secondary craters are usually more shallow at a given diameter than a primary, perhaps due to lower fragment impact speeds or self-burial during multiple, simultaneous impacts (McEwen and Bierhaus 2005). To first order, very cold ice and rock respond similarly to impact cratering, with predictable differences due to differences in strength, equations of state, etc. But Europa's surface is enigmatic: pervasive fracturing suggests a solid, competent material; chaos features and mobility of blocks within chaos suggest fluid-like behavior; radar measurements (Black et al. 2001) support the presence of a porous surface layer, as do thermal inertia models (Spencer 2004) -- though the thermal inertia only addresses the uppermost few cm. The d/D similarity of secondary craters on icy Europa and rocky surfaces (the Moon and Mars), whose surface evolutions are dominated by different processes, implies that either (a) material properties play a small role in the morphology of secondary craters, or (b) whatever processes operate to create Europa's surface features must leave the ice in a form that responds to cratering in a manner consistent with regoliths on other solar system surfaces. NASA Outer Planets Program funds this research.

  18. Automatic segmentation and diameter measurement of coronary artery vessels

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Tang, Zhenyu; Pauli, Josef

    2011-03-01

    This work presents a hybrid method for 2D artery vessel segmentation and diameter measurement in X-Ray angiograms. The proposed method is novel in that tracking-based and model-based approaches are combined. A robust and efficient tracking template, the "annular template", is devised for vessel tracking. It can readily be applied on X-Ray angiograms without any preprocessing. Starting from an initial tracking point given by the user the tracking algorithm iteratively repositions the annular template and thereby detects the vessel boundaries and possible bifurcations. With a user selected end point the tracking process results in a set of points that describes the contour and topology of an artery vessel segment between the initial and end points. A "boundary correction and interpolation" operation refines the extracted points which initialize the Snakes algorithm. Boundary correction adjusts the points to ensure that they lie on the vessel segment of interest. Boundary interpolation adds more points, so that there are sufficiently many points for the Snakes algorithm to generate a smooth and accurate vessel segmentation. After the application of Snakes the resulting points are sequentially connected to represent the vessel contour. Then, the diameters are measured along the extracted vessel contour. The segmentation and measurement results are compared with manually extracted and measured vessel segments. The average Precision, Recall and Jaccard Index of 21 vessel samples are 91.5%, 92.1% and 84.9%, respectively. Compared with ground truth measurements of diameters the average relative error is 8.2%, and the average absolute error is 1.13 pixels.

  19. Development of Small Diameter Nanofiber Tissue Engineered Arterial Grafts

    PubMed Central

    Tara, Shuhei; Rocco, Kevin A.; Bagi, Paul S.; Yi, Tai; Udelsman, Brooks; Zhuang, Zhen W.; Cleary, Muriel; Iwakiri, Yasuko; Breuer, Christopher K.; Shinoka, Toshiharu

    2015-01-01

    The surgical repair of heart and vascular disease often requires implanting synthetic grafts. While synthetic grafts have been successfully used for medium-to-large sized arteries, applications for small diameter arteries (<6 mm) is limited due to high rates of occlusion by thrombosis. Our objective was to develop a tissue engineered vascular graft (TEVG) for small diameter arteries. TEVGs composed of polylactic acid nanofibers with inner luminal diameter between 0.5 and 0.6 mm were surgically implanted as infra-renal aortic interposition conduits in 25 female C17SCID/bg mice. Twelve mice were given sham operations. Survival of mice with TEVG grafts was 91.6% at 12 months post-implantation (sham group: 83.3%). No instances of graft stenosis or aneurysmal dilatation were observed over 12 months post-implantation, assessed by Doppler ultrasound and microCT. Histologic analysis of explanted TEVG grafts showed presence of CD31-positive endothelial monolayer and F4/80-positive macrophages after 4, 8, and 12 months in vivo. Cells positive for α-smooth muscle actin were observed within TEVG, demonstrating presence of smooth muscle cells (SMCs). Neo-extracellular matrix consisting mostly of collagen types I and III were observed at 12 months post-implantation. PCR analysis supports histological observations. TEVG group showed significant increases in expressions of SMC marker, collagen-I and III, matrix metalloproteinases-2 and 9, and itgam (a macrophage marker), when compared to sham group. Overall, patency rates were excellent at 12 months after implantation, as structural integrity of these TEVG. Tissue analysis also demonstrated vessel remodeling by autologous cell. PMID:25830942

  20. A solar cycle lengthwise series of solar diameter measurements

    NASA Astrophysics Data System (ADS)

    Penna, J. L.; Andrei, A. H.; Boscardin, S. C.; Neto, E. Reis; d'Ávila, V. A.

    2010-02-01

    The measurements of the solar photospheric diameter rank among the most difficult astronomic observations. Reasons for this are the fuzzy definition of the limb, the SNR excess, and the adverse daytime seeing condition. As a consequence there are very few lengthy and consistent time series of such measurements. Using modern techniques, just the series from the IAG/USP and from Calern/OCA span more than one solar cycle. The Rio de Janeiro Group observations started in 1997, and therefore in 2008 one complete solar cycle time span can be analyzed. The series shares common principles of observation and analysis with the ones afore mentioned, and it is complementary on time to them. The distinctive features are the larger number of individual points and the improved precision. The series contains about 25,000 single observations, evenly distributed on a day-by-day basis. The typical error of a single observation is half an arc-second, enabling us to investigate variations at the expected level of tens of arc-second on a weekly basis. These features prompted to develop a new methodology for the investigation of the heliophysical scenarios leading to the observed variations, both on time and on heliolatitude. The algorithms rely on running averages and time shifts to derive the correlation and statistical incertitude for the comparison of the long term and major episodes variations of the solar diameter against activity markers. The results bring support to the correlation between the diameter variation and the solar activity, but evidentiating two different regimens for the long term trend and the major solar events.

  1. 1085 nm Nd:YVO4 laser intracavity pumped at 914 nm and sum-frequency mixing to reach cyan laser at 496 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Xia, J.; Yin, X. D.; Wang, D.; Zhang, X. H.

    2010-01-01

    We present for the first time a Nd:YVO4 laser at 1085 nm intracavity pumped at 914 nm by a Nd:YVO4 laser. We obtained intracavity powers of 57 W at 914 nm and 62 W at 1085 nm. Using type-I critical phase-matching LiB3O5 (LBO) crystal, a cyan laser at 496 nm is obtained by 914 and 1085 nm intracavity sum-frequency mixing. The maximum laser output power of 142 mW is obtained when an incident pump laser of 19.6 W is used.

  2. SERS Raman Sensor Based on Diameter-Modulated Sapphire Fiber

    SciTech Connect

    Shimoji, Yutaka

    2010-08-09

    Surface enhanced Raman scattering (SERS) has been observed using a sapphire fiber coated with gold nano-islands for the first time. The effect was found to be much weaker than what was observed with a similar fiber coated with silver nanoparticles. Diameter-modulated sapphire fibers have been successfully fabricated on a laser heated pedestal growth system. Such fibers have been found to give a modest increase in the collection efficiency of induced emission. However, the slow response of the SERS effect makes it unsuitable for process control applications.

  3. Hoop tensile strength testing of small diameter ceramic particles

    NASA Astrophysics Data System (ADS)

    Wereszczak, A. A.; Jadaan, O. M.; Lin, H.-T.; Champoux, G. J.; Ryan, D. P.

    2007-03-01

    A method to measure hoop tensile strength of 1-mm-diameter brittle ceramic spheres was demonstrated through the use of a 'C-sphere' flexure strength specimen. This innovative specimen geometry was chosen because a simple, monotonically increasing uniaxial compressive force produces a hoop tensile stress at the C-sphere's outer surface that ultimately initiates fracture. This enables strength quantification and strength-limiting-flaw identification of the sphere itself. Such strength information is relevant to design optimization and durability assessments of ceramic fuel particles and breeder/multiplier pebbles for fusion when particle surfaces are subjected to tensile stresses during their manufacturing or service.

  4. Radio source orientation and the angular diameter-redshift relation

    SciTech Connect

    Onuora, L.I. )

    1991-08-01

    The effect of a nonrandom source orientation on the angular diameter-redshift relation was considered for the 3CR sample of Laing et al., based on the 'unified' scheme of Barthel. For an inhomogeneous sample of objects displaying milliarcsecond scale structure, it was found that there was no evidence for a systematic variation for orientation angle with redshift. However, if it was assumed that quasars are closer to the line of sight than powerful extended radio galaxies, then the observed angular size-redshift relation could be interpreted in terms of source orientation, rather than linear size evolution. 14 refs.

  5. Predicting the Tube Diameter in Melts and Solutions

    NASA Astrophysics Data System (ADS)

    Milner, Scott

    2004-03-01

    A simple conjecture relating chain dimensions to the so-called ``tube diameter'', which represents the topological confining effect of entanglements on a chain, works well for all flexible entangled polymer melts. I extend this conjecture to semidilute solutions: first for theta solvents, where it is shown to be equivalent to the Colby-Rubinstein scaling picture, and then for good solvents. In the latter case, it turns out that the number of ``blobs'' per entanglement strand B is not a constant as had been previously assumed, but depends on the ratio of the packing length to the Edwards length. This unified picture is in agreement with existing data on semidilute solutions.

  6. Note: Computer controlled rotation mount for large diameter optics

    NASA Astrophysics Data System (ADS)

    Rakonjac, Ana; Roberts, Kris O.; Deb, Amita B.; Kjærgaard, Niels

    2013-02-01

    We describe the construction of a motorized optical rotation mount with a 40 mm clear aperture. The device is used to remotely control the power of large diameter laser beams for a magneto-optical trap. A piezo-electric ultrasonic motor on a printed circuit board provides rotation with a precision better than 0.03° and allows for a very compact design. The rotation unit is controlled from a computer via serial communication, making integration into most software control platforms straightforward.

  7. Structure Optimization and Evaluation of Small Adjustable Diameter Grinding Wheel

    NASA Astrophysics Data System (ADS)

    Yao, Yiyong; Li, Yuanyuan; Zhao, Liping; Zhao, Hu

    Focus on the uneven deformation of conventional adjustable diameter grinding wheel (ADGW), a structure optimization and evaluation method of ADGW was proposed in this paper. Firstly, the evaluation index system and structure optimization framework of ADGW was established to obtain the optimization objective of ADGW. Then a simulated experiment was provided. The flexible units of ADGW with different structures and geometries were selected to analyze the unevenness of deformation. The comparison results showed that the proposed method can improve the ADGW structures effectively and provide a technical approach for evaluating the structure design of ADGW.

  8. Tracking of vessel diameter fluctuations using digital image analysis

    NASA Astrophysics Data System (ADS)

    Aggarwal, Shanti J.; Yip, C.-Y.; Diller, Kenneth R.; Bovik, Alan C.

    1990-05-01

    An automatic digital image processing technique for vasomotion analysis in peripheral microcirculation at multiple sites simultaneously and in real time, is presented. The algorithm utilizes either fluorescent or bright field microimages of the vasculature as input. The video images are digitized and analyzed on-line by an IBM RT PC. Using digital filtering and edge detection, the technique allows simultaneous diameter measurement at more than one site. The sampling frequency is higher than 5 Hz when only one site is tracked. The performance of the algorithm is tested in the hamster cutaneous microcirculation.

  9. Electrically-pumped 850-nm micromirror VECSELs.

    SciTech Connect

    Geib, Kent Martin; Peake, Gregory Merwin; Serkland, Darwin Keith; Keeler, Gordon Arthur; Mar, Alan

    2005-02-01

    Vertical-external-cavity surface-emitting lasers (VECSELs) combine high optical power and good beam quality in a device with surface-normal output. In this paper, we describe the design and operating characteristics of an electrically-pumped VECSEL that employs a wafer-scale fabrication process and operates at 850 nm. A curved micromirror output coupler is heterogeneously integrated with AlGaAs-based semiconductor material to form a compact and robust device. The structure relies on flip-chip bonding the processed epitaxial material to an aluminum nitride mount; this heatsink both dissipates thermal energy and permits high frequency modulation using coplanar traces that lead to the VECSEL mesa. Backside emission is employed, and laser operation at 850 nm is made possible by removing the entire GaAs substrate through selective wet etching. While substrate removal eliminates absorptive losses, it simultaneously compromises laser performance by increasing series resistance and degrading the spatial uniformity of current injection. Several aspects of the VECSEL design help to mitigate these issues, including the use of a novel current-spreading n type distributed Bragg reflector (DBR). Additionally, VECSEL performance is improved through the use of a p-type DBR that is modified for low thermal resistance.

  10. The Use of Narrow Diameter Implants in the Molar Area.

    PubMed

    Saad, M; Assaf, A; Gerges, E

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  11. Polymer scaffolds for small-diameter vascular tissue engineering.

    PubMed

    Ma, Haiyun; Hu, Jiang; Ma, Peter X

    2010-09-01

    To better engineer small-diameter blood vessels, a few types of novel scaffolds were fabricated from biodegradable poly(L-lactic acid) (PLLA) by means of thermally induced phase separation (TIPS) techniques. By utilizing the differences in thermal conductivities of the mold materials, the scaffolds with oriented gradient microtubular structures in axial or radial direction were created using benzene as the solvent. The porosity, tubular size, and the orientation direction of the microtubules can be controlled by polymer concentration, TIPS temperature, and materials of different thermal conductivities. The gradient microtubular structure was intended to facilitate cell seeding and mass transfer for cell growth and function. We also developed nanofibrous scaffolds with oriented and interconnected micro-tubular pore network by a one-step TIPS method using benzene/tetrahydrofuran mixture as the solvent without using porogen materials. The structural features of such scaffolds can be conveniently adjusted by varying the solvent ratio, phase separation temperature and polymer concentration to mimic the nanofibrous feature of extracellular matrix. These scaffolds were fabricated for the tissue engineering of small-diameter blood vessels by utilizing their advantageous structural features to facilitate blood vessel regeneration. PMID:24501590

  12. Polymer scaffolds for small-diameter vascular tissue engineering

    PubMed Central

    Ma, Haiyun; Hu, Jiang; Ma, Peter X

    2014-01-01

    To better engineer small-diameter blood vessels, a few types of novel scaffolds were fabricated from biodegradable poly(L-lactic acid) (PLLA) by means of thermally induced phase separation (TIPS) techniques. By utilizing the differences in thermal conductivities of the mold materials, the scaffolds with oriented gradient microtubular structures in axial or radial direction were created using benzene as the solvent. The porosity, tubular size, and the orientation direction of the microtubules can be controlled by polymer concentration, TIPS temperature, and materials of different thermal conductivities. The gradient microtubular structure was intended to facilitate cell seeding and mass transfer for cell growth and function. We also developed nanofibrous scaffolds with oriented and interconnected micro-tubular pore network by a one-step TIPS method using benzene/tetrahydrofuran mixture as the solvent without using porogen materials. The structural features of such scaffolds can be conveniently adjusted by varying the solvent ratio, phase separation temperature and polymer concentration to mimic the nanofibrous feature of extracellular matrix. These scaffolds were fabricated for the tissue engineering of small-diameter blood vessels by utilizing their advantageous structural features to facilitate blood vessel regeneration. PMID:24501590

  13. The Use of Narrow Diameter Implants in the Molar Area

    PubMed Central

    Saad, M.; Assaf, A.; Gerges, E.

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  14. 33-Foot-Diameter Space Station Leading to Space Base

    NASA Technical Reports Server (NTRS)

    1969-01-01

    This picture illustrates a concept of a 33-Foot-Diameter Space Station Leading to a Space Base. In-house work of the Marshall Space Flight Center, as well as a Phase B contract with the McDornel Douglas Astronautics Company, resulted in a preliminary design for a space station in 1969 and l970. The Marshall-McDonnel Douglas approach envisioned the use of two common modules as the core configuration of a 12-man space station. Each common module was 33 feet in diameter and 40 feet in length and provided the building blocks, not only for the space station, but also for a 50-man space base. Coupled together, the two modules would form a four-deck facility: two decks for laboratories and two decks for operations and living quarters. Zero-gravity would be the normal mode of operation, although the station would have an artificial gravity capability. This general-purpose orbital facility was to provide wide-ranging research capabilities. The design of the facility was driven by the need to accommodate a broad spectrum of activities in support of astronomy, astrophysics, aerospace medicine, biology, materials processing, space physics, and space manufacturing. To serve the needs of Earth observations, the station was to be placed in a 242-nautical-mile orbit at a 55-degree inclination. An Intermediate-21 vehicle (comprised of Saturn S-IC and S-II stages) would have launched the station in 1977.

  15. Allowable pillar to diameter ratio for strategic petroleum reserve caverns.

    SciTech Connect

    Ehgartner, Brian L.; Park, Byoung Yoon

    2011-05-01

    This report compiles 3-D finite element analyses performed to evaluate the stability of Strategic Petroleum Reserve (SPR) caverns over multiple leach cycles. When oil is withdrawn from a cavern in salt using freshwater, the cavern enlarges. As a result, the pillar separating caverns in the SPR fields is reduced over time due to usage of the reserve. The enlarged cavern diameters and smaller pillars reduce underground stability. Advances in geomechanics modeling enable the allowable pillar to diameter ratio (P/D) to be defined. Prior to such modeling capabilities, the allowable P/D was established as 1.78 based on some very limited experience in other cavern fields. While appropriate for 1980, the ratio conservatively limits the allowable number of oil drawdowns and hence limits the overall utility and life of the SPR cavern field. Analyses from all four cavern fields are evaluated along with operating experience gained over the past 30 years to define a new P/D for the reserve. A new ratio of 1.0 is recommended. This ratio is applicable only to existing SPR caverns.

  16. Measurements of Pupillary Diameter and Wavefront Aberrations in Pregnant Women

    PubMed Central

    Altay, Mehmet Metin; Demirok, Gulizar; Balta, Ozgur; Bolu, Hulya

    2016-01-01

    Purpose. To show whether pregnancy affects the measurements of pupillary diameter and wavefront (WF) aberrations. Methods. This was a case-control study including 34 healthy pregnant women in the third trimester and age-matched 34 nonpregnant women. Only women who had no ocular abnormalities and no refractive error were included. We measured photopic and mesopic pupil diameter and WF aberrations at the third trimester and at the second postpartum month. Measurements of the right eyes were used in this study. The differences between groups were analysed by paired t-test and t-test. Results. Pregnant women's mean photopic pupil size in the third trimester was significantly higher than in postpartum period and in control group (3.74 ± 0.77, 3.45 ± 0.53, and 3.49 ± 0.15 mm, p < 0.05, resp.). Mesopic pupil size in the third trimester was also higher than in postpartum period and in control group (6.77 ± 0.52, 6.42 ± 0.55, and 6.38 ± 0.21 mm, p < 0.05, resp.). RMS-3 and RMS-5 values were higher in pregnancy but these differences were not statistically significant. Conclusion. Pregnancy increased photopic and mesopic pupil size significantly but did not increase wavefront aberrations notably. Increased pupil size may be due to increased sympathetic activity during pregnancy. And this activity can be noninvasively determined by measuring pupil size. PMID:26998383

  17. Large diameter femoral heads: is bigger always better?

    PubMed

    Cooper, H J; Della Valle, C J

    2014-11-01

    Dislocation remains among the most common complications of, and reasons for, revision of both primary and revision total hip replacements (THR). Hence, there is great interest in maximising stability to prevent this complication. Head size has been recognised to have a strong influence on the risk of dislocation post-operatively. As femoral head size increases, stability is augmented, secondary to an increase in impingement-free range of movement. Larger head sizes also greatly increase the 'jump distance' required for the head to dislocate in an appropriately positioned cup. Level-one studies support the use of larger diameter heads as they decrease the risk of dislocation following primary and revision THR. Highly cross-linked polyethylene has allowed us to increase femoral head size, without a marked increase in wear. However, the thin polyethylene liners necessary to accommodate larger heads may increase the risk of liner fracture and larger heads have also been implicated in causing soft-tissue impingement resulting in groin pain. Larger diameter heads also impart larger forces on the femoral trunnion, which may contribute to corrosion, metal release, and adverse local tissue reactions. Alternative large bearings including large ceramic heads and dual mobility bearings may mitigate some of these risks, and several of these devices have been used with clinical success. PMID:25381403

  18. The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces

    SciTech Connect

    Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W

    2009-10-29

    Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as {tau}{sup 0.3} for sites in the 50-100 {micro}m size range.

  19. Sub-5 nm nanostructures fabricated by atomic layer deposition using a carbon nanotube template.

    PubMed

    Woo, Ju Yeon; Han, Hyo; Kim, Ji Weon; Lee, Seung-Mo; Ha, Jeong Sook; Shim, Joon Hyung; Han, Chang-Soo

    2016-07-01

    The fabrication of nanostructures having diameters of sub-5 nm is very a important issue for bottom-up nanofabrication of nanoscale devices. In this work, we report a highly controllable method to create sub-5 nm nano-trenches and nanowires by combining area-selective atomic layer deposition (ALD) with single-walled carbon nanotubes (SWNTs) as templates. Alumina nano-trenches having a depth of 2.6 ∼ 3.0 nm and SiO2 nano-trenches having a depth of 1.9 ∼ 2.2 nm fully guided by the SWNTs have been formed on SiO2/Si substrate. Through infilling ZnO material by ALD in alumina nano-trenches, well-defined ZnO nanowires having a thickness of 3.1 ∼ 3.3 nm have been fabricated. In order to improve the electrical properties of ZnO nanowires, as-fabricated ZnO nanowires by ALD were annealed at 350 °C in air for 60 min. As a result, we successfully demonstrated that as-synthesized ZnO nanowire using a specific template can be made for various high-density resistive components in the nanoelectronics industry. PMID:27188268

  20. Novel optical signatures of sub-3 nm rare earth sesquioxide nanocrystals.

    NASA Astrophysics Data System (ADS)

    Dickerson, James; Mahajan, Sameer

    2008-03-01

    Europium and terbium based sesquioxide nanomaterials, known for their characteristic red and green luminescence, respectively, have recently garnered much research attention due to their size-dependent optical properties. Here, we present systematic investigation of the size-dependent optical properties Eu2O3, Tb2O3, and Gd2O3:Eu^3+ / Tb^3+ nanocrystals (NCs) in the size range of 1-3 nm in diameter. We observe a new luminescence peak at 620 nm in Eu2O3 and Gd2O3:Eu^3+ NCs, which represents modulation of the ^7F2 transition in Eu^3+ ion. Intensity modulation with respect to the 612 nm is observed as a function of nanocrystal size. For the Tb2O3 NCs, a new luminescence signature at 548 nm characterizes modulation of the ^7F5 transition in Tb^3+ ion. In addition, we probe the effect of NC size on the luminescence efficiencies of the doped and pure sesquioxide NCs. The concentration quenching effect, which leads to low luminescence efficiencies in bulk, pure sesquioxides, is explored in sub-3 nm sesquioxides.

  1. Sub-5 nm nanostructures fabricated by atomic layer deposition using a carbon nanotube template

    NASA Astrophysics Data System (ADS)

    Woo, Ju Yeon; Han, Hyo; Kim, Ji Weon; Lee, Seung-Mo; Ha, Jeong Sook; Shim, Joon Hyung; Han, Chang-Soo

    2016-07-01

    The fabrication of nanostructures having diameters of sub-5 nm is very a important issue for bottom-up nanofabrication of nanoscale devices. In this work, we report a highly controllable method to create sub-5 nm nano-trenches and nanowires by combining area-selective atomic layer deposition (ALD) with single-walled carbon nanotubes (SWNTs) as templates. Alumina nano-trenches having a depth of 2.6 ∼ 3.0 nm and SiO2 nano-trenches having a depth of 1.9 ∼ 2.2 nm fully guided by the SWNTs have been formed on SiO2/Si substrate. Through infilling ZnO material by ALD in alumina nano-trenches, well-defined ZnO nanowires having a thickness of 3.1 ∼ 3.3 nm have been fabricated. In order to improve the electrical properties of ZnO nanowires, as-fabricated ZnO nanowires by ALD were annealed at 350 °C in air for 60 min. As a result, we successfully demonstrated that as-synthesized ZnO nanowire using a specific template can be made for various high-density resistive components in the nanoelectronics industry.

  2. Length scaling of carbon nanotube electric and photo diodes down to sub-50 nm.

    PubMed

    Xu, Haitao; Wang, Sheng; Zhang, Zhiyong; Peng, Lian-Mao

    2014-09-10

    Carbon nanotubes (CNTs) are promising candidates for future optoelectronics and logic circuits.1-3 Sub-10 nm channel length CNT transistors have been demonstrated with superb performance.4 Yet, the scaling of CNT p-n diodes or photodiodes, basic elements for most optoelectronic devices, is held back on a scale of micrometers.5-8 Here, we demonstrate that CNT diodes fabricated via a dopant-free technique show good rectifying characteristics and photovoltaic response even when the channel length is scaled to sub-50 nm. By making a trade-off between performance and size, a diode with both channel length and contact width around 100 nm, fabricated on a CNT with a small diameter (d ∼ 1.2 nm), shows a photovoltage of 0.24 V and a fill factor of up to 60%. Study on the dependence of turn-on voltage on scaled channel length reveals transferred charges induced potential barrier at the contact in long channel diodes and the effect of self-adjusting charge distribution. This effect could be utilized for realizing stable and high performance sub-100 nm pitch CNT diodes. As elementary building blocks, such tiny electric and photodiodes could be used in nanoscale rectifiers, photodetectors, light sources, and high-efficiency photovoltaic devices. PMID:25115287

  3. TCSPC FLIM in the wavelength range from 800 nm to 1700 nm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Becker, Wolfgang; Shcheslavsky, Vladislav

    2016-03-01

    Excitation and detection in the wavelength range above 800nm is a convenient and relatively inexpensive way to increase the penetration depth in optical microscopy. Moreover, detection at long wavelength avoids the problem that tissue autofluorescence contaminates the signals from endogenous fluorescence probes. FLIM at NIR wavelength may therefore be complementary to multiphoton microscopy, especially if the lifetimes of NIR fluorophores report biological parameters of the tissue structures they are bound to. Unfortunately, neither the excitation sources nor the detectors of standard confocal and multiphoton laser scanning systems are directly suitable for excitation and detection of NIR fluorescence. Most of these problems can be solved, however, by using ps diode lasers or Ti:Sapphire lasers at their fundamental wavelength, and NIR-sensitive detectors. With NIR-sensitive PMTs the detection wavelength range can be extended up to 900 nm, with InGaAs SPAD detectors up to 1700 nm. Here, we demonstrate the use of a combination of laser scanning, multi-dimensional TCSPC, and advanced excitation sources and detectors for FLIM at up to 1700 nm. The performance was tested at tissue samples incubated with NIR dyes. The fluorescence lifetimes generally get shorter with increasing absorption and emission wavelengths of the dyes. For the cyanine dye IR1061, absorbing around 1060 nm, the lifetime was found to be as short as 70 ps. Nevertheless the fluorescence decay could still be clearly detected. Almost all dyes showed clear lifetime changes depending on the binding to different tissue constituents.

  4. High power diode lasers emitting from 639 nm to 690 nm

    NASA Astrophysics Data System (ADS)

    Bao, L.; Grimshaw, M.; DeVito, M.; Kanskar, M.; Dong, W.; Guan, X.; Zhang, S.; Patterson, J.; Dickerson, P.; Kennedy, K.; Li, S.; Haden, J.; Martinsen, R.

    2014-03-01

    There is increasing market demand for high power reliable red lasers for display and cinema applications. Due to the fundamental material system limit at this wavelength range, red diode lasers have lower efficiency and are more temperature sensitive, compared to 790-980 nm diode lasers. In terms of reliability, red lasers are also more sensitive to catastrophic optical mirror damage (COMD) due to the higher photon energy. Thus developing higher power-reliable red lasers is very challenging. This paper will present nLIGHT's released red products from 639 nm to 690nm, with established high performance and long-term reliability. These single emitter diode lasers can work as stand-alone singleemitter units or efficiently integrate into our compact, passively-cooled Pearl™ fiber-coupled module architectures for higher output power and improved reliability. In order to further improve power and reliability, new chip optimizations have been focused on improving epitaxial design/growth, chip configuration/processing and optical facet passivation. Initial optimization has demonstrated promising results for 639 nm diode lasers to be reliably rated at 1.5 W and 690nm diode lasers to be reliably rated at 4.0 W. Accelerated life-test has started and further design optimization are underway.

  5. Dual illumination OCT at 1050nm and 840nm for whole eye segment imaging

    NASA Astrophysics Data System (ADS)

    Fan, Shanhui; Qin, Lin; Dai, Cuixia; Zhou, Chuanqing

    2014-11-01

    We presented an improved dual channel dual focus spectral domain optical coherence tomography (SD-OCT) with two illuminations at 840 nm and 1050 nm for whole eye segment imaging and biometry in vivo. The two light beams were coupled and optically optimized to scan the anterior and posterior segment of the eye simultaneously. This configuration with dichroic mirrors integrated in the sample arm enables us to acquire images from the anterior segment and retina effectively with minimum loss of sample signal. In addition, the full resolved complex (FRC) method was applied to double the imaging depth for the whole anterior segment imaging by eliminating the mirror image. The axial resolution for 1050 nm and 840 nm OCT was 14 μm and 8 μm in air, respectively. Finally, the system was successfully tested in imaging the unaccommodated and accommodated eyes. The preliminary results demonstrated the significant improvements comparing with our previous dual channel SD-OCT configuration in which the two probing beams had the same central wavelength of 840 nm.

  6. Size dependent compressibility of nano-ceria: Minimum near 33 nm

    SciTech Connect

    Rodenbough, Philip P.; Song, Junhua; Chan, Siu-Wai; Walker, David; Clark, Simon M.; Kalkan, Bora

    2015-04-20

    We report the crystallite-size-dependency of the compressibility of nanoceria under hydrostatic pressure for a wide variety of crystallite diameters and comment on the size-based trends indicating an extremum near 33 nm. Uniform nano-crystals of ceria were synthesized by basic precipitation from cerium (III) nitrate. Size-control was achieved by adjusting mixing time and, for larger particles, a subsequent annealing temperature. The nano-crystals were characterized by transmission electron microscopy and standard ambient x-ray diffraction (XRD). Compressibility, or its reciprocal, bulk modulus, was measured with high-pressure XRD at LBL-ALS, using helium, neon, or argon as the pressure-transmitting medium for all samples. As crystallite size decreased below 100 nm, the bulk modulus first increased, and then decreased, achieving a maximum near a crystallite diameter of 33 nm. We review earlier work and examine several possible explanations for the peaking of bulk modulus at an intermediate crystallite size.

  7. 308-nm excimer laser in endodontics

    NASA Astrophysics Data System (ADS)

    Liesenhoff, Tim

    1992-06-01

    Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

  8. Surface micromachined MEMS tunable VCSEL at 1550 nm with > 70 nm single mode tuning

    NASA Astrophysics Data System (ADS)

    Gierl, Christian; Gründl, Tobias; Debernardi, Pierluigi; Zogal, Karolina; Davani, Hooman A.; Grasse, Christian; Böhm, Gerhard; Meissner, Peter; Küppers, Franko; Amann, Markus-Christian

    2012-03-01

    We present surface micro-machined tunable vertical-cavity surface-emitting lasers (VCSELs) operating around 1550nm with tuning ranges up to 100nm and side mode suppression ratios beyond 40 dB. The output power reaches 3.5mW at 1555 nm. The electro-thermal and the electro-statical actuation of a micro electro-mechanical system (MEMS) movable distributed Bragg reflector (DBR) membrane increases/decreases the cavity length which shifts the resonant wavelength of the cavity to higher/lower values. The wavelength is modulated with 200 Hz/120 kHz. Both tuning mechanisms can be used simultaneously within the same device. The newly developed surface micro-machining technology uses competitive dielectric materials for the MEMS, deposited with low temperature plasma enhanced chemical vapor deposition (PECVD), which is cost effective and capable for on wafer mass production.

  9. A Small Diameter Rosette for Sampling Ice Covered Waters

    NASA Astrophysics Data System (ADS)

    Chayes, D. N.; Smethie, W. M.; Perry, R. S.; Schlosser, P.; Friedrich, R.

    2011-12-01

    A gas tight, small diameter, lightweight rosette, supporting equipment and an effective operational protocol has been developed for aircraft supported sampling of sea water across the Lincoln Sea. The system incorporates a commercial off the shelf CTD electronics (SBE19+ sensor package and SBE33 deck unit) to provide real-time measurement data at the surface. We designed and developed modular water sample units and custom electronics to decode the bottle firing commands and close the sample bottles. For a typical station, we land a ski-equipped deHaviland Twin Otter (DHC-6) aircraft on a suitable piece of sea-ice, drill a 12" diameter hole through the ice next to the cargo door and set up a tent to provide a reasonable working environment over the hole. A small winch with 0.1" diameter single conductor cable is mounted in the aircraft by the cargo door and a tripod supports a sheave above the hole. The CTD module is connected to the end of the wire and the water sampling modules are stacked on top as the system is lowered. For most stations, three sample modules are used to provide 12 four (4) liter sample bottles. Data collected during the down-cast is used to formulate the sampling plan which is executed on the up-cast. The system is powered by a 3,700 Watt, 120VAC gasoline generator. After collection, the sample modules are stored in passively temperature stabilized ice chests during the flight back to the logistics facility at Alert where a broad range of samples are drawn and stored for future analysis. The transport mechanism has a good track record of maintaining water samples within about two degrees of the original collection temperature which minimizes out-gassing. The system has been successfully deployed during a field program each spring starting in 2004 along a transect between the north end of Ellesmere Island (Alert, Nunavut) and the North Pole. During the eight field programs we have taken 48 stations with twelve bottles at most stations (eight at

  10. Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

    NASA Astrophysics Data System (ADS)

    Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

    2016-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

  11. Absorption Measurements of Periodically Poled Potassium Titanyl Phosphate (PPKTP) at 775 nm and 1550 nm

    PubMed Central

    Steinlechner, Jessica; Ast, Stefan; Krüger, Christoph; Singh, Amrit Pal; Eberle, Tobias; Händchen, Vitus; Schnabel, Roman

    2013-01-01

    The efficient generation of second-harmonic light and squeezed light requires non-linear crystals that have low absorption at the fundamental and harmonic wavelengths. In this work the photo-thermal self-phase modulation technique is exploited to measure the absorption coefficient of periodically poled potassium titanyl phosphate (PPKTP) at 1,550 nm and 775 nm. The measurement results are (84±40) ppm/cm and (127±24) ppm/cm, respectively. We conclude that the performance of state-of-the-art frequency doubling and squeezed light generation in PPKTP is not limited by absorption. PMID:23291574

  12. The Doubling of 846 nm Light to Produce 423 nm Light for use in Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Archibald, James; Birrell, Jeremey; Tang, Rebecca; Erickson, Chris; Goggins, Landon; Durfee, Dallin

    2009-10-01

    We present progress on a 423 nm fluorescence probe/cooling laser for use in our neutral calcium atom interferometer. The finished system will include an 846 nm diode laser that is coupled to a tapered amplifier. This light will be sent to a buildup cavity where we will achieve second-harmonic generation (SHG) using either a BBO non-linear crystal or a periodically-poled KTP crystal. We will discuss the theoretical considerations relating to the doubling of light in a crystal and the construction of our buildup cavity. We will also discuss its proposed application for use in atom interferometry.

  13. Plume diagnostics and room-temperature deposition of carbon nanotubes and nano-onions at 248 nm

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, G.; Adams, P. M.; Ross, F. D.

    2007-04-01

    We report on the deposition of carbon nanotubes and nano-onions at room temperature using excimer laser radiation at 248 nm to ablate mixed graphite-nickel/cobalt targets in the presence of O2 gas. The carbon nanotubes are frequently seen to connect individual onions and have a wall thickness on the order of 20-25 nm, with an overall external tube diameter of 100-200 nm. These tubes have notably large channel diameters and are significantly larger than typically reported single and multi-walled carbon nanotubes. The observed onion structures are both single and clustered and are 100-200 nm in diameter. Ablation of the same targets in comparable pressures of Ar does not result in these nanostructures but instead produces amorphous carbon. Ablating a pure graphite target under the same laser conditions, with or without metal, also does not yield the tubes and onions. In-situ time-resolved emission spectroscopy has been used to follow the emission from molecular carbon such as C2, as well as metals such as Ni or Co in the different ambients.

  14. HVOF thermal spray process for internal diameter applications

    SciTech Connect

    Poe, M.W.

    1994-12-31

    Thermal spray has been selected as the coating process of choice for many OEM and repair/restoration applications. Although the thermal spray process has historically been limited to coating `line-of-sight` surfaces, advances in thermal spray equipment design now allow protective and/or restorative coatings to be applied to deep internal diameters utilizing state-of-the-art HVOF processing. The advanced designs include both `standard` and `mini` torches to coat rotating components, plus a rotating extension for coating stationary ID`s. In addition, a wide range of coating materials has been developed and engineered to combat the deleterious effects of wear found in severe service environments. The resultant coatings have exceptionally high bond strength with no interconnected porosity and low residual stress. This unique process provides an important adjunct to the field of thermal spray process capabilities.

  15. Solar furnace satellite for large diameter crystal growth in space

    NASA Technical Reports Server (NTRS)

    Overfelt, Tony; Wells, Mark; Blake, John

    1993-01-01

    Investigators worldwide are preparing experiments to test the influence of low gravity found in space on the growth of many crystalline materials. However, power limitations prevent existing space crystal growth furnaces from being able to process samples any larger than about 2 cm, and in addition, the background microgravity levels found on the Space Shuttle are not low enough to significantly benefit samples much larger than 2 cm. This paper describes a novel concept of a free-flying platform utilizing well-established solar furnace technology to enable materials processing in space experiments on large-diameter crystals. The conceptual design of this Solar Furnace Satellite is described along with its operational scenario and the anticipated g levels.

  16. Density profile control in a large diameter, helicon plasma

    SciTech Connect

    Cluggish, B.P.; Anderegg, F.A.; Freeman, R.L.; Gilleland, J.; Hilsabeck, T.J.; Isler, R.C.; Lee, W.D.; Litvak, A.A.; Miller, R.L.; Ohkawa, T.; Putvinski, S.; Umstadter, K.R.; Winslow, D.L.

    2005-05-15

    Plasmas with peaked radial density profiles have been generated in the world's largest helicon device, with plasma diameters of over 70 cm. The density profiles can be manipulated by controlling the phase of the current in each strap of two multistrap antenna arrays. Phase settings that excite long axial wavelengths create hollow density profiles, whereas settings that excite short axial wavelengths create peaked density profiles. This change in density profile is consistent with the cold-plasma dispersion relation for helicon modes, which predicts a strong increase in the effective skin depth of the rf fields as the wavelength decreases. Scaling of the density with magnetic field, gas pressure, and rf power is also presented.

  17. Preparation of Aligned Ultra-long and Diameter-controlled Silicon Oxide Nanotubes by Plasma Enhanced Chemical Vapor Deposition Using Electrospun PVP Nanofiber Template

    NASA Astrophysics Data System (ADS)

    Zhou, Ming; Zhou, Jinyuan; Li, Ruishan; Xie, Erqing

    2010-02-01

    Well-aligned and suspended polyvinyl pyrrolidone (PVP) nanofibers with 8 mm in length were obtained by electrospinning. Using the aligned suspended PVP nanofibers array as template, aligned ultra-long silicon oxide (SiO x) nanotubes with very high aspect ratios have been prepared by plasma-enhanced chemical vapor deposition (PECVD) process. The inner diameter (20-200 nm) and wall thickness (12-90 nm) of tubes were controlled, respectively, by baking the electrospun nanofibers and by coating time without sacrificing the orientation degree and the length of arrays. The micro-PL spectrum of SiO x nanotubes shows a strong blue-green emission with a peak at about 514 nm accompanied by two shoulders around 415 and 624 nm. The blue-green emission is caused by the defects in the nanotubes.

  18. Size-controlled large-diameter and few-walled carbon nanotube catalysts for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Wang, Xianliang; Li, Qing; Pan, Hengyu; Lin, Ye; Ke, Yujie; Sheng, Haiyang; Swihart, Mark T.; Wu, Gang

    2015-11-01

    We demonstrate a new strategy for tuning the size of large-diameter and few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50 to 150 nm by varying the transition metal (TM = Fe, Co, Ni or Mn) used to catalyze graphitization of dicyandiamide. Fe yielded the largest tubes, followed by Co and Ni, while Mn produced a clot-like carbon morphology. We show that morphology is correlated with electrocatalytic activity for the oxygen reduction reaction (ORR). A clear trend of Fe > Co > Ni > Mn for the ORR catalytic activity was observed, in both alkaline media and more demanding acidic media. The Fe-derived N-CNTs exhibited the highest BET (~870 m2 g-1) and electrochemically accessible (~450 m2 g-1) surface areas and, more importantly, the highest concentration of nitrogen incorporated into the carbon planes. Thus, in addition to the intrinsic high activity of Fe-derived catalysts, the high surface area and nitrogen doping contribute to high ORR activity. This work, for the first time, demonstrates size-controlled synthesis of large-diameter N-doped carbon tube electrocatalysts by varying the metal used in N-CNT generation. Electrocatalytic activity of the Fe-derived catalyst is already the best among studied metals, due to the high intrinsic activity of possible Fe-N coordination. This work further provides a promising route to advanced Fe-N-C nonprecious metal catalysts by generating favorable morphology with more active sites and improved mass transfer.We demonstrate a new strategy for tuning the size of large-diameter and few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50 to 150 nm by varying the transition metal (TM = Fe, Co, Ni or Mn) used to catalyze graphitization of dicyandiamide. Fe yielded the largest tubes, followed by Co and Ni, while Mn produced a clot-like carbon morphology. We show that morphology is correlated with electrocatalytic activity for the oxygen reduction reaction (ORR). A clear trend of Fe > Co > Ni > Mn for the ORR catalytic

  19. White matter microstructure from nonparametric axon diameter distribution mapping.

    PubMed

    Benjamini, Dan; Komlosh, Michal E; Holtzclaw, Lynne A; Nevo, Uri; Basser, Peter J

    2016-07-15

    We report the development of a double diffusion encoding (DDE) MRI method to estimate and map the axon diameter distribution (ADD) within an imaging volume. A variety of biological processes, ranging from development to disease and trauma, may lead to changes in the ADD in the central and peripheral nervous systems. Unlike previously proposed methods, this ADD experimental design and estimation framework employs a more general, nonparametric approach, without a priori assumptions about the underlying form of the ADD, making it suitable to analyze abnormal tissue. In the current study, this framework was used on an ex vivo ferret spinal cord, while emphasizing the way in which the ADD can be weighted by either the number or the volume of the axons. The different weightings, which result in different spatial contrasts, were considered throughout this work. DDE data were analyzed to derive spatially resolved maps of average axon diameter, ADD variance, and extra-axonal volume fraction, along with a novel sub-micron restricted structures map. The morphological information contained in these maps was then used to segment white matter into distinct domains by using a proposed k-means clustering algorithm with spatial contiguity and left-right symmetry constraints, resulting in identifiable white matter tracks. The method was validated by comparing histological measures to the estimated ADDs using a quantitative similarity metric, resulting in good agreement. With further acquisition acceleration and experimental parameters adjustments, this ADD estimation framework could be first used preclinically, and eventually clinically, enabling a wide range of neuroimaging applications for improved understanding of neurodegenerative pathologies and assessing microstructural changes resulting from trauma. PMID:27126002

  20. Evaluation of small diameter coreholes for reservoir information

    SciTech Connect

    Petty, Susan; Adair, Richard G.; Livesay, Bill

    1992-01-01

    Geothermal exploration has been highly successful to date in locating targets for drilling. However, the requirements for an economically successful geothermal well are both high flow rate and high temperature. Most geophysical and geochemical exploration methods have not been highly accurate in predicting the depth and actual temperature of a reservoir, nor have they been able to locate high permeability zones. The result is that most geothermal exploration is conducted by drilling core holes to better understand the heat flow in an area followed by drilling of production diameter exploration wells which can be flow tested to ascertain the permeability. The goal of any exploration program is to determine reservoir economics. The cost of wells makes up between one quarter and one half the total cost of producing geothermal power. The number, design, depth of wells and placement of injectors are important to the optimal exploitation of the reservoir. Although early efforts at development have focused on rapid plant construction to begin cash flow, the history of producing fields emphasizes that understanding reservoirs can reduce the risk of rapid temperature or pressure declines and increase the success of step out drilling following initial exploitation. The high cost of large diameter production wells makes the collecting of exploration data on the reservoir through some less expensive method desirable. Geothermal developers are still drilling resources with surface expression, hot springs and surface mappable fractures and faults. As these obvious resources are developed and as the obvious targets in productive fields are exhausted, new exploration tools are needed. One possibility is the use of deep core holes drilled for temperature gradient data to provide more reservoir information. Two methods not previously applied to geothermal reservoir assessment are suggested to augment other data obtained from coreholes.

  1. Automatic detection and estimation of biparietal diameter from fetal ultrasonography

    NASA Astrophysics Data System (ADS)

    Annangi, Pavan; Banerjee Krishnan, Kajoli; Banerjee, Jyotirmoy; Gupta, Madhumita; Patil, Uday

    2011-03-01

    Fetal bi-parietal diameter (BPD) is known to provide a reliable estimate of gestational age (GA) of a fetus in the first half of pregnancy. In this paper, we present an automated method to identify and measure BPD from B-mode ultrasound images of fetal head. The method (a) automatically detects and places a region-of-interest on the head based on a prior work in our group (b) utilizes the concept of phase congruency for edge detection and (c) employs a cost function to identify the third ventricle inside the head (d) measures the BPD along the perpendicular bisector of occipital frontal diameter (OFD) from the outer rim of the cranium closer to the transducer to the inner rim of the cranium away from the transducer. The cost function is premised on the distribution of anatomical shape, size and presentation of the third ventricle in images that adhere to clinical guidelines describing the scan plane for BPD measurement. The OFD is assumed to lie along the third ventricle. The algorithm has been tested on 137 images acquired from four different scanners. Based on GA estimates and their bounds specified in Standard Obstetric Tables, the GA predictions from automated measurements are found to be within +/-2SD of GA estimates from manual measurements by the operator and a second expert radiologist in 98% of the cases. The method described in this paper can also be adapted to assess the accuracy of the scan plane based on the presence/absence of the third ventricle.

  2. Decellularized ovine arteries as small-diameter vascular grafts.

    PubMed

    Mancuso, L; Gualerzi, A; Boschetti, F; Loy, F; Cao, G

    2014-08-01

    Atherosclerosis and its complications still represent the leading cause of death in the developed countries. While autologous blood vessels may be regarded as the best solution for peripheral and coronary bypass, they are unavailable in most patients. Even though tissue engineering techniques are often applied to the development of small-diameter vascular grafts, limiting factors of this approach are represented by the lack of essential extracellular matrix proteins and/or poor biomechanical properties of the scaffolds used. Along these lines, the aim of this study was to develop a decellularization protocol for ovine carotids to be used as suitable small-diameter vascular grafts. Samples were treated either with sodium dodecyl sulphate (SDS) or with Trypsin and Triton X-100; a final nuclease digestion was performed for both protocols. Morphological analyses demonstrate complete removal of nuclei and cellular components in treated vessels, also confirmed by significant reduction in wall thickness and DNA content. Essential extracellular matrix proteins such as collagen, elastin, and fibronectin are well preserved after decellularization. From a mechanical point of view, Trypsin and Triton X-100 treated arteries show elastic modules and compliance comparable to native carotids, whereas the use of SDS makes samples stiffer, with a significant decrease in the compliance mean value and an increase in longitudinal and circumferential Young's modules. It is demonstrated that the treatment where Trypsin and Triton X-100 are combined guarantees complete decellularization of carotids, with no significant alteration of biomechanical and structural properties, thus preserving a suitable environment for adhesion, proliferation, and migration of cells. PMID:25050540

  3. Axon diameters and conduction velocities in the macaque pyramidal tract

    PubMed Central

    Firmin, L.; Field, P.; Maier, M. A.; Kraskov, A.; Kirkwood, P. A.; Nakajima, K.; Lemon, R. N.

    2014-01-01

    Small axons far outnumber larger fibers in the corticospinal tract, but the function of these small axons remains poorly understood. This is because they are difficult to identify, and therefore their physiology remains obscure. To assess the extent of the mismatch between anatomic and physiological measures, we compared conduction time and velocity in a large number of macaque corticospinal neurons with the distribution of axon diameters at the level of the medullary pyramid, using both light and electron microscopy. At the electron microscopic level, a total of 4,172 axons were sampled from 2 adult male macaque monkeys. We confirmed that there were virtually no unmyelinated fibers in the pyramidal tract. About 14% of pyramidal tract axons had a diameter smaller than 0.50 μm (including myelin sheath), most of these remaining undetected using light microscopy, and 52% were smaller than 1 μm. In the electrophysiological study, we determined the distribution of antidromic latencies of pyramidal tract neurons, recorded in primary motor cortex, ventral premotor cortex, and supplementary motor area and identified by pyramidal tract stimulation (799 pyramidal tract neurons, 7 adult awake macaques) or orthodromically from corticospinal axons recorded at the mid-cervical spinal level (192 axons, 5 adult anesthetized macaques). The distribution of antidromic and orthodromic latencies of corticospinal neurons was strongly biased toward those with large, fast-conducting axons. Axons smaller than 3 μm and with a conduction velocity below 18 m/s were grossly underrepresented in our electrophysiological recordings, and those below 1 μm (6 m/s) were probably not represented at all. The identity, location, and function of the majority of corticospinal neurons with small, slowly conducting axons remains unknown. PMID:24872533

  4. Association between abdominal aortic diameter and peripheral vascular disease.

    PubMed

    Rajkumar, C; Bonapace, S; Starr, J; Radia, M; Bulpitt, C J

    1997-09-01

    Fifty-four elderly people 81.2 years +/- 7.4 (mean age +/- s.d., range 66-98 years) were selected. These included 20 men (78.6 +/- 6.4 years, range 70-91 years) and 34 women (82.2 +/- 7.6 years, range 66-98 years). The relationship between the size of the abdominal aorta and various cardiovascular risk indicators such as calf:-brachial systolic pressure ratio, plasma cholesterol, triglycerides, and random blood glucose were examined. Abdominal aortic diameter correlated well with calf:-brachial systolic ratio measured by Doppler method over the posterior tibial artery and taking the lowest result of the right and left side (r = -0.28, P = 0.04). This correlation tended to be stronger in men (r = -0.55, P = 0.02) compared to women (r = -0.10, P = 0.57). However, the relationship tended to be confined to the systolic pressure in the left leg, raising the hypothesis that left-sided vascular disease is better related to aortic diameter, possibly due to a difference in the effects of reflected waves between the two sides. This needs further investigation. The contrast between the sexes was seen in the absence of any significant difference in resting blood pressure and calf:brachial systolic pressure ratio between the two. This finding suggests that the sex differences in the relationship between the size of the abdominal aorta and calf:brachial systolic pressure ratio are related to intrinsic properties of the arterial wall. PMID:9364278

  5. Fabrication of sub-15 nm aluminum wires by controlled etching

    SciTech Connect

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; Marković, N.; McQueen, T. M.

    2014-04-28

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  6. Photodissociation of the Propargyl (C3D3) Radicals at 248 nm and 193 nm

    SciTech Connect

    Neumark., D.M.; Crider, P.E.; Castiglioni, L.; Kautzman, K.K.

    2009-01-21

    The photodissociation of perdeuterated propargyl (D{sub 2}CCCD) and propynyl (D{sub 3}CCC) radicals was investigated using fast beam photofragment translational spectroscopy. Radicals were produced from their respective anions by photodetachment at 540 nm and 450 nm (below and above the electron affinity of propynyl). The radicals were then photodissociated by 248 nm or 193 nm light. The recoiling photofragments were detected in coincidence with a time- and position-sensitive detector. Three channels were observed: D{sub 2} loss, CD + C{sub 2}D{sub 2}, and CD{sub 3} + C{sub 2}. Obervation of the D loss channel was incompatible with this experiment and was not attempted. Our translational energy distributions for D{sub 2} loss peaked at nonzero translational energy, consistent with ground state dissociation over small (< 1 eV) exit barriers with respect to separated products. Translational energy distributions for the two heavy channels peaked near zero kinetic energy, indicating dissociation on the ground state in the absence of exit barriers.

  7. Characterization of LANDSAT Panels Using the NIST BRDF Scale from 1100 nm to 2500 nm

    NASA Technical Reports Server (NTRS)

    Markham, Brian; Tsai, Benjamin K.; Allen, David W.; Cooksey, Catherine; Yoon, Howard; Hanssen, Leonard; Zeng, Jinan; Fulton, Linda; Biggar, Stuart; Markham, Brian

    2010-01-01

    Many earth observing sensors depend on white diffuse reflectance standards to derive scales of radiance traceable to the St Despite the large number of Earth observing sensors that operate in the reflective solar region of the spectrum, there has been no direct method to provide NIST traceable BRDF measurements out to 2500 rim. Recent developments in detector technology have allowed the NIST reflectance measurement facility to expand the operating range to cover the 250 nm to 2500 nm range. The facility has been modified with and additional detector using a cooled extended range indium gallium arsenide (Extended InGaAs) detector. Measurements were made for two PTFE white diffuse reflectance standards over the 1100 nm to 2500 nm region at a 0' incident and 45' observation angle. These two panels will be used to support the OLI calibration activities. An independent means of verification was established using a NIST radiance transfer facility based on spectral irradiance, radiance standards and a diffuse reflectance plaque. An analysis on the results and associated uncertainties will be discussed.

  8. THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

    SciTech Connect

    Redman, Stephen L.; Nave, Gillian; Sansonetti, Craig J.

    2014-03-01

    We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19, 874 thorium lines between 250 nm and 5500 nm (40, 000 cm{sup –1} to 1800 cm{sup –1}). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer and Engleman and typographical errors and incorrect classifications in Kerber et al. We also found a large scatter with respect to the thorium line list of Lovis and Pepe. We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

  9. Broadband supercontinuum generation in normal dispersion all-solid photonic crystal fiber pumped near 1300 nm

    NASA Astrophysics Data System (ADS)

    Stepniewski, G.; Klimczak, M.; Bookey, H.; Siwicki, B.; Pysz, D.; Stepien, R.; Kar, A. K.; Waddie, A. J.; Taghizadeh, M. R.; Buczynski, R.

    2014-05-01

    We report on octave-spanning supercontinuum generation under pumping with 1360 nm, 120 fs pulses, in an all-solid, all-normal dispersion photonic crystal fiber. The fiber was drawn from thermally matched oxide soft glasses with a hexagonal lattice 35 µm in diameter, 2.5 µm solid core and pitch of Λ/d = 0.9. The fiber was designed for normal dispersion broadly flattened in the 1200-2800 nm range. Experimentally recorded supercontinuum spectrum covered a 900-1900 nm bandwidth and was reconstructed with good agreement using numerical modeling. To the best of our knowledge, this is the first report of an experimentally demonstrated octave-spanning supercontinuum bandwidth, reaching as far as 1900 nm in the all-normal dispersion regime.

  10. Faster qualification of 193-nm resists for 100-nm development using photo cell monitoring

    NASA Astrophysics Data System (ADS)

    Jones, Chris M.; Kallingal, Chidam; Zawadzki, Mary T.; Jeewakhan, Nazneen N.; Kaviani, Nazila N.; Krishnan, Prakash; Klaum, Arthur D.; Van Ess, Joel

    2003-05-01

    The development of 100-nm design rule technologies is currently taking place in many R&D facilities across the world. For some critical alyers, the transition to 193-nm resist technology has been required to meet this leading edge design rule. As with previous technology node transitions, the materials and processes available are undergoing changes and improvements as vendors encounter and solve problems. The initial implementation of the 193-nm resits process did not meet the photolithography requirements of some IC manufacturers due to very high Post Exposure Bake temperature sensitivity and consequently high wafer to wafer CD variation. The photoresist vendors have been working to improve the performance of the 193-nm resists to meet their customer's requirements. Characterization of these new resists needs to be carried out prior to implementation in the R&D line. Initial results on the second-generation resists evaluated at Cypress Semicondcutor showed better CD control compared to the aelrier resist with comparable Depth of Focus (DOF), Exposure Latitute, Etch Resistance, etc. In addition to the standard lithography parameters, resist characterization needs to include defect density studies. It was found that the new resists process with the best CD control, resulted in the introduction of orders of magnitude higher yield limiting defects at Gate, Contact adn Local Interconnect. The defect data were shared with the resists vendor and within days of the discovery the resist vendor was able to pinpoint the source of the problem. The fix was confirmed and the new resists were successfully released to production. By including defect monitoring into the resist qualification process, Cypress Semiconductor was able to 1) drive correction actions earlier resulting in faster ramp and 2) eliminate potential yield loss. We will discuss in this paper how to apply the Micro Photo Cell Monitoring methodology for defect monitoring in the photolithogprhay module and the

  11. Direct Patterning of CdSe Quantum Dots into Sub-100 nm Structures

    SciTech Connect

    Hampton, Meredith J.; Templeton, Joseph L.; DeSimone, Joseph M.

    2010-03-02

    Ordered, two-dimensional cadmium selenide (CdSe) arrays have been fabricated on indium-doped tin oxide (ITO) electrodes using the pattern replication in nonwetting templates (PRINT) process. CdSe quantum dots (QDs) with an average diameter of 2.7 nm and a pyridine surface ligand were used for patterning. The PRINT technique utilizes a perfluoropolyether (PFPE) elastomeric mold that is tolerant of most organic solvents, thus allowing solutions of CdSe QDs in 4-picoline to be used for patterning without significant deformation of the mold. Nanometer-scale diffraction gratings have been successfully replicated with CdSe QDs.

  12. High performance wafer-fused semiconductor disk lasers emitting in the 1300 nm waveband.

    PubMed

    Sirbu, Alexei; Rantamäki, Antti; Saarinen, Esa J; Iakovlev, Vladimir; Mereuta, Alexandru; Lyytikäinen, Jari; Caliman, Andrei; Volet, Nicolas; Okhotnikov, Oleg G; Kapon, Eli

    2014-12-01

    We report for the first time on the performance of 1300 nm waveband semiconductor disc lasers (SDLs) with wafer fused gain mirrors that implement intracavity diamond and flip-chip heat dissipation schemes based on the same gain material. With a new type of gain mirror structure, maximum output power values reach 7.1 W with intracavity diamond gain mirrors and 5.6 W with flip-chip gain mirrors, using a pump spot diameter of 300 µm, exhibiting a beam quality factor M(2)< 1.25 in the full operation range. These results confirm previously published theoretical modeling of these types of SDLs. PMID:25606874

  13. A novel method to encapsulate a Au nanorod array in 15 nm radius multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liao, Gaomin; Pan, Yuanyuan; Wu, Qiang; Li, Shaoyun; Weng, Yuyan; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Tsui, Ophelia K. C.

    2014-11-01

    In this paper we demonstrate a novel complex array structure comprising well-aligned Au nanorods (10 nm in diameter) encapsulated inside 15 nm radius multiwalled carbon nanotubes (MWCNTs). A pre-aligned and open-ended nanoporous MWCNT membrane is used as the starting material. Au nanorods are precisely deposited and aligned inside the hollow channels of CNTs by inter-diffusing the HAuCl4 precursor and the reductant solution. Ultra-long Au nanowires and spherical Au nanoparticles are also observed in the CNT cavity with the same diameter in special cases. Using high-resolution TEM (HRTEM), scanning transmission electron microscopy (STEM), 3-dimensional TEM (3D-TEM) and energy dispersive X-ray spectroscopy (EDX), the precise location and composition of the encapsulated Au components with various structures are confirmed. This aligned Au@CNT endohedral material has important potential applications in nanocatalysis, waveguides, as well as in novel plasmonic devices.In this paper we demonstrate a novel complex array structure comprising well-aligned Au nanorods (10 nm in diameter) encapsulated inside 15 nm radius multiwalled carbon nanotubes (MWCNTs). A pre-aligned and open-ended nanoporous MWCNT membrane is used as the starting material. Au nanorods are precisely deposited and aligned inside the hollow channels of CNTs by inter-diffusing the HAuCl4 precursor and the reductant solution. Ultra-long Au nanowires and spherical Au nanoparticles are also observed in the CNT cavity with the same diameter in special cases. Using high-resolution TEM (HRTEM), scanning transmission electron microscopy (STEM), 3-dimensional TEM (3D-TEM) and energy dispersive X-ray spectroscopy (EDX), the precise location and composition of the encapsulated Au components with various structures are confirmed. This aligned Au@CNT endohedral material has important potential applications in nanocatalysis, waveguides, as well as in novel plasmonic devices. Electronic supplementary information (ESI

  14. Manufacturing of 100mm diameter GaSb substrates for advanced space based applications

    NASA Astrophysics Data System (ADS)

    Allen, L. P.; Flint, J. P.; Meshew, G.; Trevethan, J.; Dallas, G.; Khoshakhlagh, A.; Hill, C. J.

    2012-01-01

    Engineered substrates such as large diameter (100mm) GaSb wafers need to be ready years in advance of any major shift in DoD and commercial technology, and typically before much of the rest of the materials and equipment for fabricating next generation devices. Antimony based III-V semiconductors are of significant interest for advanced applications in optoelectronics, high speed transistors, microwave devices, and photovoltaics. GaSb demand is increasing due to its lattice parameter matching of various ternary and quaternary III-V compounds, as their bandgaps can be engineered to cover a wide spectral range. For these stealth and spaced based applications, larger format IRFPAs benefit clearly from next generation starting substrates. In this study, we have manufactured and tested 100mm GaSb substrates. This paper describes the characterization process that provides the best possible GaSb material for advanced IRFPA and SLS epi growth. The analysis of substrate by AFM surface roughness, particles, haze, GaSb oxide character and desorption using XPS, flatness measurements, and SLS based epitaxy quality are shown. By implementing subtle changes in our substrate processing, we show that a Sb-oxide rich surface is routinely provided for rapid desorption. Post-MBE CBIRD structures on the 100mm ULD GaSb were examined and reveals a high intensity, 6.6nm periodicity, low (15.48 arcsec) FWHM peak distribution that suggests low surface strain and excellent lattice matching. The Ra for GaSb is a consistent ~0.2-4nm, with average batch wafer warp of ~4 μm to provide a clean, flat GaSb template critical for next generation epi growth.

  15. Correlation of the ratio of caudal vena cava diameter and aorta diameter with systolic pressure variation in anesthetized dogs.

    PubMed

    Meneghini, Caterina; Rabozzi, Roberto; Franci, Paolo

    2016-02-01

    OBJECTIVE To evaluate the correlation coefficient of the ratio between diameter of the caudal vena cava (CVC) and diameter of the aorta (Ao) in dogs as determined ultrasonographically with systolic pressure variation (SPV). ANIMALS 14 client-owned dogs (9 females and 5 males; mean ± SD age, 73 ± 40 months; mean body weight, 22 ± 7 kg) that underwent anesthesia for repair of skin wounds. PROCEDURES Anesthesia was induced. Controlled mechanical ventilation with a peak inspiratory pressure of 8 cm H2O was immediately started, and SPV was measured. During a brief period of suspension of ventilation, CVC-to-Ao ratio was measured on a transverse right-lateral intercostal ultrasonographic image obtained at the level of the porta hepatis. When the SPV was ≥ 4 mm Hg, at least 1 bolus (3 to 4 mL/kg) of Hartmann solution was administered IV during a 1-minute period. Bolus administration was stopped and the CVC-to-Ao ratio measured when SPV was < 4 mm Hg. Correlation coefficient analysis was performed. RESULTS 28 measurements were obtained. The correlation coefficient was 0.86 (95% confidence interval, 0.72 to 0.93). Mean ± SD SPV and CVC-to-Ao ratio before bolus administration were 7 ± 2 mm Hg and 0.52 ± 0.16, respectively. Mean ± SD SPV and CVC-to-Ao ratio after bolus administration were 2 ± 0.6 mm Hg and 0.91 ± 0.13, respectively. CONCLUSIONS AND CLINICAL RELEVANCE In this study, the CVC-to-Ao ratio was a feasible, noninvasive ultrasonographically determined value that correlated well with SPV. (Am J Vet Res 2016;77:137-143). PMID:27027706

  16. Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure

    NASA Astrophysics Data System (ADS)

    Fairuz Budiman, Mohd; Hu, Weiguo; Igarashi, Makoto; Tsukamoto, Rikako; Isoda, Taiga; Itoh, Kohei M.; Yamashita, Ichiro; Murayama, Akihiro; Okada, Yoshitaka; Samukawa, Seiji

    2012-02-01

    A sub-10 nm, high-density, periodic silicon-nanodisc (Si-ND) array has been fabricated using a new top-down process, which involves a 2D array bio-template etching mask made of Listeria-Dps with a 4.5 nm diameter iron oxide core and damage-free neutral-beam etching (Si-ND diameter: 6.4 nm). An Si-ND array with an SiO2 matrix demonstrated more controllable optical bandgap energy due to the fine tunability of the Si-ND thickness and diameter. Unlike the case of shrinking Si-ND thickness, the case of shrinking Si-ND diameter simultaneously increased the optical absorption coefficient and the optical bandgap energy. The optical absorption coefficient became higher due to the decrease in the center-to-center distance of NDs to enhance wavefunction coupling. This means that our 6 nm diameter Si-ND structure can satisfy the strict requirements of optical bandgap energy control and high absorption coefficient for achieving realistic Si quantum dot solar cells.

  17. Superconducting nanowire single photon detector at 532 nm and demonstration in satellite laser ranging.

    PubMed

    Li, Hao; Chen, Sijing; You, Lixing; Meng, Wengdong; Wu, Zhibo; Zhang, Zhongping; Tang, Kai; Zhang, Lu; Zhang, Weijun; Yang, Xiaoyan; Liu, Xiaoyu; Wang, Zhen; Xie, Xiaoming

    2016-02-22

    Superconducting nanowire single-photon detectors (SNSPDs) at a wavelength of 532 nm were designed and fabricated aiming to satellite laser ranging (SLR) applications. The NbN SNSPDs were fabricated on one-dimensional photonic crystals with a sensitive-area diameter of 42 μm. The devices were coupled with multimode fiber (ϕ = 50 μm) and exhibited a maximum system detection efficiency of 75% at an extremely low dark count rate of <0.1 Hz. An SLR experiment using an SNSPD at a wavelength of 532 nm was successfully demonstrated. The results showed a depth ranging with a precision of ~8.0 mm for the target satellite LARES, which is ~3,000 km away from the ground ranging station at the Sheshan Observatory. PMID:26907010

  18. Threshold and efficiency for perforation of 1 nm thick carbon nanomembranes with slow highly charged ions

    NASA Astrophysics Data System (ADS)

    Wilhelm, Richard A.; Gruber, Elisabeth; Ritter, Robert; Heller, René; Beyer, André; Turchanin, Andrey; Klingner, Nico; Hübner, René; Stöger-Pollach, Michael; Vieker, Henning; Hlawacek, Gregor; Gölzhäuser, Armin; Facsko, Stefan; Aumayr, Friedrich

    2015-09-01

    Cross-linking of a self-assembled monolayer of 1,1‧-biphenyl-4-thiol by low energy electron irradiation leads to the formation of a carbon nanomembrane, that is only 1 nm thick. Here we study the perforation of these freestanding membranes by slow highly charged ion irradiation with respect to the pore formation yield. It is found that a threshold in potential energy of the highly charged ions of about 10 keV must be exceeded in order to form round pores with tunable diameters in the range of 5-15 nm. Above this energy threshold, the efficiency for a single ion to form a pore increases from 70% to nearly 100% with increasing charge. These findings are verified by two independent methods, namely the analysis of individual membranes stacked together during irradiation and the detailed analysis of exit charge state spectra utilizing an electrostatic analyzer.

  19. Tapered large-core 976 nm Yb-doped fiber laser with 10 W output power

    NASA Astrophysics Data System (ADS)

    Leich, M.; Jäger, M.; Grimm, S.; Hoh, D.; Jetschke, S.; Becker, M.; Hartung, A.; Bartelt, H.

    2014-04-01

    We report on a tapered large-core Yb fiber laser operating at 976 nm emission wavelength. It was realized using a high-numerical aperture large-core fiber with 126 μm core diameter, which was fabricated by powder-sinter technology and shows a very homogeneous step-index profile. The end of the fiber is tapered down to match a single-mode fiber containing a fiber Bragg grating. Using the benefits of core-pumping and the feedback of the spliced fiber Bragg grating, we achieved efficient pump light absorption and wavelength stable 976 nm lasing with single-mode performance. We could demonstrate 10 W laser power out of a 10 μm fiber core with a slope efficiency of 31% with respect to the launched pump power. The presented device is well-suited for fiber-coupled pumping of amplifiers for high peak power.

  20. Core level photoionization on free sub-10-nm nanoparticles using synchrotron radiation

    SciTech Connect

    Meinen, Jan; Leisner, Thomas; Khasminskaya, Svetlana; Eritt, Markus; Antonsson, Egill; Langer, Burkhard; Ruehl, Eckart

    2010-08-15

    A novel instrument is presented, which permits studies on singly charged free nanoparticles in the diameter range from 1 to 30 nm using synchrotron radiation in the soft x-ray regime. It consists of a high pressure nanoparticle source, a high efficiency nanoparticle beam inlet, and an electron time-of-flight spectrometer suitable for probing surface and bulk properties of free, levitated nanoparticles. We show results from x-ray photoelectron spectroscopy study near the Si L{sub 3,2}-edge on 8.2 nm SiO{sub 2} particles prepared in a nanoparticle beam. The possible use of this apparatus regarding chemical reactions on the surface of nanometer-sized particles is highlighted. This approach has the potential to be exploited for process studies on heterogeneous atmospheric chemistry.